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+# Messaging UI SDK — Foundation (Plan 1 of 3) Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Build the transport-free core of `@insignia/iios-messaging-ui` — types, the `MessagingAdapter` contract, a shared conformance suite, a mock adapter, and the provider + hooks — proving the seam works with zero network.
+
+**Architecture:** The core knows nothing about any transport. Hosts inject a `MessagingAdapter`; the provider holds it in context; hooks (`useConversations`, `useMessages`) call it. `iios-kernel-client` is reachable only from the `./adapters/kernel` subpath (Plan 3), never from core — enforced by a test, not convention. A conformance suite defines "a correct adapter" once, so the mock, kernel, and CRM adapters are all verified against one definition.
+
+**Tech Stack:** TypeScript, React 19 (peer), tsup (ESM), vitest 3 + jsdom + @testing-library/react, pnpm workspaces.
+
+**Spec:** `lynkeduppro-crm/docs/superpowers/specs/2026-07-17-messaging-sdk-design.md`
+
+**Scope of this plan:** Package scaffold, test infra, types, adapter contract + conformance suite, mock adapter, provider, hooks, boundary enforcement. **Out of scope:** UI components and CSS (Plan 2); kernel adapter, CRM adapter, attachments, and the CRM migration (Plan 3).
+
+---
+
+## Context an engineer needs
+
+**Read these first:**
+- `packages/iios-message-web/` — the existing headless package. **This is the anti-pattern**, not the model: 109 lines, narrowed `send` API, no consumers. We are deliberately building the layer it refused to build.
+- `lynkeduppro-crm/src/lib/messenger-api.ts` — the source of the adapter contract. Its `MessengerData`/`ThreadData` interfaces already survived two implementations (live + mock).
+- `scripts/check-import-boundary.mjs` — the repo's dependency law.
+
+**Repo facts that will bite you:**
+- Root `vitest.config.ts` includes only `packages/**/src/**/*.{test,spec}.ts` — **`.tsx` is not matched**, and its `globalSetup` provisions a Postgres DB on port 5434 for every run. This package therefore gets its **own** `vitest.config.ts` with `environment: 'jsdom'` and **no** `globalSetup`. Never add a DB dependency to a pure-UI package.
+- `tsconfig.base.json` sets `"module": "commonjs"` — every web package overrides this to `ESNext` + `moduleResolution: bundler` + `jsx: react-jsx`. Copy that override; don't fight the base.
+- Packages are ESM-only (`"type": "module"`).
+
+**The bug we are fixing (do not port it):** the CRM infers the current actor id by scanning for a message you sent (`messenger-api.ts:200-203`). Until you have sent in a thread, `myActorId` is `null`, so the REST poll fallback computes `mine: false` for **every** message. Root cause: the kernel's receipt event carries no `threadId`. Our fix is `adapter.currentActorId()` — identity is the adapter's job, stated explicitly. Task 8 has the regression test.
+
+---
+
+## File Structure
+
+| File | Responsibility |
+|---|---|
+| `packages/iios-messaging-ui/package.json` | Package manifest, exports map, scripts |
+| `packages/iios-messaging-ui/tsup.config.ts` | ESM build, 3 entries (core, adapters/mock, adapters/kernel) |
+| `packages/iios-messaging-ui/tsconfig.json` | ESNext + jsx override over base |
+| `packages/iios-messaging-ui/vitest.config.ts` | jsdom, includes `.tsx`, **no** globalSetup |
+| `src/types.ts` | Domain types only. Zero imports. |
+| `src/adapter.ts` | The `MessagingAdapter` interface |
+| `src/conformance.ts` | Shared suite defining a correct adapter (shipped, not test-only) |
+| `src/conformance.test.ts` | Runs the suite against the mock adapter |
+| `src/adapters/mock.ts` | In-memory adapter for demos/tests |
+| `src/provider.tsx` | `MessagingProvider` + `useAdapter` |
+| `src/hooks/use-conversations.ts` | Conversation list state |
+| `src/hooks/use-messages.ts` | Thread state, optimistic send, subscribe reconciliation |
+| `src/index.ts` | Public barrel |
+| `src/boundary.test.ts` | Asserts core never imports a transport |
+
+Files split by responsibility, not layer. `conformance.ts` ships in `src/` (not a test file) because Plan 3's adapters import it to verify themselves.
+
+---
+
+### Task 1: Package scaffold + test infrastructure
+
+**Files:**
+- Create: `packages/iios-messaging-ui/package.json`
+- Create: `packages/iios-messaging-ui/tsconfig.json`
+- Create: `packages/iios-messaging-ui/tsup.config.ts`
+- Create: `packages/iios-messaging-ui/vitest.config.ts`
+- Create: `packages/iios-messaging-ui/src/index.ts`
+- Test: `packages/iios-messaging-ui/src/smoke.test.tsx`
+
+- [ ] **Step 1: Create the package manifest**
+
+Create `packages/iios-messaging-ui/package.json`:
+
+```json
+{
+  "name": "@insignia/iios-messaging-ui",
+  "version": "0.1.0",
+  "type": "module",
+  "main": "dist/index.js",
+  "module": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js"
+    },
+    "./adapters/mock": {
+      "types": "./dist/adapters/mock.d.ts",
+      "import": "./dist/adapters/mock.js"
+    },
+    "./conformance": {
+      "types": "./dist/conformance.d.ts",
+      "import": "./dist/conformance.js"
+    },
+    "./styles.css": "./dist/styles.css"
+  },
+  "files": [
+    "dist"
+  ],
+  "scripts": {
+    "build": "tsup",
+    "typecheck": "tsc --noEmit",
+    "test": "vitest run"
+  },
+  "peerDependencies": {
+    "react": ">=18"
+  },
+  "devDependencies": {
+    "@testing-library/dom": "^10.4.0",
+    "@testing-library/react": "^16.1.0",
+    "@types/react": "^19.0.0",
+    "jsdom": "^26.0.0",
+    "react": "^19.0.0",
+    "react-dom": "^19.0.0",
+    "tsup": "^8.3.5",
+    "typescript": "^5.7.3",
+    "vitest": "^3.0.5"
+  },
+  "publishConfig": {
+    "registry": "https://git.lynkedup.cloud/api/packages/insignia/npm/"
+  }
+}
+```
+
+Note: **no `dependencies`.** The core must stay transport-free. `./adapters/kernel` and its `@insignia/iios-kernel-client` dependency arrive in Plan 3. `./styles.css` is declared now but produced in Plan 2.
+
+- [ ] **Step 2: Create tsconfig**
+
+Create `packages/iios-messaging-ui/tsconfig.json`:
+
+```json
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "outDir": "./dist",
+    "rootDir": "./src",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "lib": ["ES2022", "DOM"],
+    "jsx": "react-jsx",
+    "types": ["react"]
+  },
+  "include": ["src/**/*.ts", "src/**/*.tsx"],
+  "exclude": ["src/**/*.test.ts", "src/**/*.test.tsx"]
+}
+```
+
+- [ ] **Step 3: Create the build config**
+
+Create `packages/iios-messaging-ui/tsup.config.ts`:
+
+```ts
+import { defineConfig } from 'tsup';
+
+export default defineConfig({
+  // `conformance` is its own entry, never reachable from `index`. It imports vitest,
+  // and bundling that into the main barrel would drag a test runner into every
+  // consumer's production build.
+  entry: ['src/index.ts', 'src/adapters/mock.ts', 'src/conformance.ts'],
+  format: ['esm'],
+  dts: true,
+  clean: true,
+  external: ['react', 'react-dom', 'vitest'],
+});
+```
+
+- [ ] **Step 4: Create the package's own vitest config**
+
+Create `packages/iios-messaging-ui/vitest.config.ts`:
+
+```ts
+import { defineConfig } from 'vitest/config';
+
+// This package owns its vitest config on purpose. The ROOT config includes only
+// `.ts` (never `.tsx`) and provisions a Postgres DB via globalSetup for every run —
+// a pure-UI package must not drag a database along, and its tests are .tsx.
+export default defineConfig({
+  test: {
+    environment: 'jsdom',
+    include: ['src/**/*.{test,spec}.{ts,tsx}'],
+    globals: false,
+  },
+});
+```
+
+- [ ] **Step 5: Create a placeholder barrel**
+
+Create `packages/iios-messaging-ui/src/index.ts`:
+
+```ts
+export {};
+```
+
+- [ ] **Step 6: Write the failing smoke test**
+
+Create `packages/iios-messaging-ui/src/smoke.test.tsx`:
+
+```tsx
+import { describe, it, expect } from 'vitest';
+import { render, screen } from '@testing-library/react';
+
+describe('test infrastructure', () => {
+  it('renders React components in jsdom', () => {
+    render(<div>messaging-ui</div>);
+    expect(screen.getByText('messaging-ui')).toBeDefined();
+  });
+});
+```
+
+- [ ] **Step 7: Install dependencies**
+
+Run from the repo root:
+
+```bash
+pnpm install
+```
+
+Expected: pnpm links the new workspace package; `@testing-library/react`, `jsdom`, `react-dom` resolve.
+
+- [ ] **Step 8: Run the test to verify it passes**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test`
+Expected: PASS, 1 test. If it fails with "document is not defined", `environment: 'jsdom'` did not take effect — check you created `vitest.config.ts` in the package dir, not the root.
+
+- [ ] **Step 9: Verify typecheck and build**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui typecheck && pnpm --filter @insignia/iios-messaging-ui build`
+Expected: no type errors; `dist/index.js` + `dist/index.d.ts` produced.
+
+- [ ] **Step 10: Commit**
+
+```bash
+git add packages/iios-messaging-ui
+git commit -m "chore: scaffold @insignia/iios-messaging-ui with jsdom test setup"
+```
+
+---
+
+### Task 2: Domain types
+
+**Files:**
+- Create: `packages/iios-messaging-ui/src/types.ts`
+- Test: `packages/iios-messaging-ui/src/types.test.ts`
+
+These are the SDK's own types — deliberately **not** re-exported from `iios-kernel-client`, because core must not depend on it. Adapters map kernel/CRM DTOs onto these. Shape is taken from the CRM's `UiConversation`/`UiMessage`/`UiPerson`, which are already proven.
+
+- [ ] **Step 1: Write the failing test**
+
+Create `packages/iios-messaging-ui/src/types.test.ts`:
+
+```ts
+import { describe, it, expect } from 'vitest';
+import { isOwnMessage } from './types';
+import type { Message } from './types';
+
+const base: Message = {
+  id: 'm1',
+  actorId: 'actor_a',
+  text: 'hello',
+  at: '2026-07-17T10:00:00.000Z',
+};
+
+describe('isOwnMessage', () => {
+  it('is true when the message actor matches the current actor', () => {
+    expect(isOwnMessage(base, 'actor_a')).toBe(true);
+  });
+
+  it('is false when the actors differ', () => {
+    expect(isOwnMessage(base, 'actor_b')).toBe(false);
+  });
+
+  it('is false when the current actor is unknown', () => {
+    expect(isOwnMessage(base, null)).toBe(false);
+  });
+
+  it('is false when the message has no actor', () => {
+    expect(isOwnMessage({ ...base, actorId: null }, 'actor_a')).toBe(false);
+  });
+});
+```
+
+- [ ] **Step 2: Run test to verify it fails**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test`
+Expected: FAIL — "Failed to resolve import ./types" or "isOwnMessage is not a function".
+
+- [ ] **Step 3: Write the implementation**
+
+Create `packages/iios-messaging-ui/src/types.ts`:
+
+```ts
+// Domain types for the messaging UI. Zero imports on purpose: this file must never
+// reach for a transport package. Adapters map their own DTOs onto these.
+
+export type Membership = 'dm' | 'group';
+
+export interface Person {
+  id: string;
+  name: string;
+  kind: 'staff' | 'customer';
+}
+
+export interface Conversation {
+  threadId: string;
+  title: string;
+  subject: string | null;
+  membership: Membership | null;
+  participants: string[];
+  unread: number;
+  lastMessage?: string;
+  lastAt?: string;
+}
+
+export interface Reaction {
+  emoji: string;
+  count: number;
+  mine: boolean;
+}
+
+export interface Attachment {
+  url: string;
+  mime: string;
+  name: string;
+}
+
+export interface Message {
+  id: string;
+  actorId: string | null;
+  text: string;
+  at: string;
+  parentInteractionId?: string | null;
+  reactions?: Reaction[];
+  attachment?: Attachment;
+  /** True only when the transport is optimistic-local and not yet acknowledged. */
+  pending?: boolean;
+}
+
+export interface SendOpts {
+  parentInteractionId?: string;
+  attachment?: Attachment;
+}
+
+export type MessageEvent =
+  | { kind: 'message'; message: Message }
+  | { kind: 'typing'; userId: string }
+  | { kind: 'receipt'; messageId: string; actorId: string }
+  | { kind: 'reaction'; messageId: string; reactions: Reaction[] };
+
+export type Unsubscribe = () => void;
+
+/** Ownership is a pure function of explicit identity — never inferred from history.
+ *  See the spec: inferring it is the bug this SDK exists partly to kill. */
+export function isOwnMessage(message: Message, currentActorId: string | null): boolean {
+  return currentActorId !== null && message.actorId !== null && message.actorId === currentActorId;
+}
+```
+
+- [ ] **Step 4: Run test to verify it passes**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test`
+Expected: PASS, 5 tests (4 new + smoke).
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add packages/iios-messaging-ui/src/types.ts packages/iios-messaging-ui/src/types.test.ts
+git commit -m "feat: add messaging-ui domain types"
+```
+
+---
+
+### Task 3: The MessagingAdapter contract
+
+**Files:**
+- Create: `packages/iios-messaging-ui/src/adapter.ts`
+
+An interface has no runtime behaviour to test directly; Task 4's conformance suite is its test. This task is type-only, so it is verified by `typecheck`.
+
+- [ ] **Step 1: Write the interface**
+
+Create `packages/iios-messaging-ui/src/adapter.ts`:
+
+```ts
+import type {
+  Attachment,
+  Conversation,
+  Membership,
+  Message,
+  MessageEvent,
+  SendOpts,
+  Unsubscribe,
+} from './types';
+
+/**
+ * The one seam of this SDK. Hosts implement this; the SDK renders it.
+ *
+ * Lifted from lynkeduppro-crm's MessengerData/ThreadData, which already survived
+ * two implementations (live data-door + mock) — the minimum real evidence that a
+ * seam is genuine rather than imagined.
+ *
+ * Optional methods degrade gracefully: the UI hides the reaction picker when
+ * `react` is absent, and the attach button when `upload` is absent. That is how one
+ * component set serves both a full CRM messenger and a stripped-down widget with no
+ * `mode` prop.
+ */
+export interface MessagingAdapter {
+  listConversations(): Promise<Conversation[]>;
+
+  openThread(p: { participantIds: string[]; membership?: Membership; subject?: string }): Promise<{ threadId: string }>;
+
+  history(threadId: string): Promise<Message[]>;
+
+  send(threadId: string, content: string, opts?: SendOpts): Promise<Message>;
+
+  /** Returns an unsubscribe fn. Implementations MUST be idempotent on repeat unsubscribe. */
+  subscribe(threadId: string, cb: (e: MessageEvent) => void): Unsubscribe;
+
+  sendTyping(threadId: string): void;
+
+  markRead(threadId: string, messageId: string): Promise<void>;
+
+  /**
+   * The current user's actor id, or null if not yet known.
+   *
+   * MUST NOT be inferred from message history. The CRM's bug was exactly that:
+   * scanning for a sent message meant every message read as not-yours until you
+   * had spoken. Adapters derive this from auth/session.
+   */
+  currentActorId(): string | null;
+
+  /** Absent => the UI hides reactions entirely. */
+  react?(threadId: string, messageId: string, emoji: string): Promise<void>;
+
+  /** Absent => the UI hides attachments. Storage/auth/limits are the host's concern. */
+  upload?(file: File): Promise<Attachment>;
+
+  /** Absent => treated as always connected (e.g. a pure-REST adapter). */
+  isConnected?(): boolean;
+}
+```
+
+- [ ] **Step 2: Verify it typechecks**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui typecheck`
+Expected: no errors.
+
+- [ ] **Step 3: Commit**
+
+```bash
+git add packages/iios-messaging-ui/src/adapter.ts
+git commit -m "feat: define MessagingAdapter contract"
+```
+
+---
+
+### Task 4: Adapter conformance suite
+
+**Files:**
+- Create: `packages/iios-messaging-ui/src/conformance.ts`
+
+This ships in `src/` (not as a `.test.ts`) because Plan 3's kernel and CRM adapters import it to verify themselves. One definition of "correct adapter", three implementations checked against it.
+
+- [ ] **Step 1: Write the suite**
+
+Create `packages/iios-messaging-ui/src/conformance.ts`:
+
+```ts
+import { describe, it, expect } from 'vitest';
+import type { MessagingAdapter } from './adapter';
+import type { MessageEvent } from './types';
+
+export interface ConformanceOptions {
+  /** Build a fresh, isolated adapter per test. */
+  makeAdapter: () => Promise<MessagingAdapter> | MessagingAdapter;
+  /** A thread id that exists in the fixture. */
+  seededThreadId: string;
+  /** Participant ids openThread can legally be called with. */
+  openWith: string[];
+}
+
+/**
+ * The definition of a correct MessagingAdapter. Every adapter runs this.
+ *
+ * Imports vitest, so it ships from the './conformance' subpath ONLY and is never
+ * reachable from the main barrel. Consumers supply their own vitest.
+ *
+ * Usage from another package:
+ *   import { runAdapterConformance } from '@insignia/iios-messaging-ui/conformance';
+ *   runAdapterConformance({ makeAdapter: () => new MockAdapter(), seededThreadId: 'th_1', openWith: ['pp_a'] });
+ */
+export function runAdapterConformance(opts: ConformanceOptions): void {
+  const make = async () => await opts.makeAdapter();
+
+  describe('MessagingAdapter conformance', () => {
+    it('lists conversations', async () => {
+      const a = await make();
+      const list = await a.listConversations();
+      expect(Array.isArray(list)).toBe(true);
+    });
+
+    it('returns history for a seeded thread', async () => {
+      const a = await make();
+      const msgs = await a.history(opts.seededThreadId);
+      expect(Array.isArray(msgs)).toBe(true);
+    });
+
+    it('send resolves with a message carrying the sent text and a stable id', async () => {
+      const a = await make();
+      const m = await a.send(opts.seededThreadId, 'conformance hello');
+      expect(m.text).toBe('conformance hello');
+      expect(typeof m.id).toBe('string');
+      expect(m.id.length).toBeGreaterThan(0);
+    });
+
+    it('a sent message is attributed to the current actor', async () => {
+      const a = await make();
+      const m = await a.send(opts.seededThreadId, 'whose is this');
+      expect(m.actorId).toBe(a.currentActorId());
+    });
+
+    it('currentActorId is known BEFORE any message is sent', async () => {
+      // The bug this SDK exists to kill: identity must come from auth, never be
+      // inferred from history. A fresh adapter already knows who you are.
+      const a = await make();
+      expect(a.currentActorId()).not.toBeNull();
+    });
+
+    it('a sent message appears in history', async () => {
+      const a = await make();
+      await a.send(opts.seededThreadId, 'persist me');
+      const msgs = await a.history(opts.seededThreadId);
+      expect(msgs.some((m) => m.text === 'persist me')).toBe(true);
+    });
+
+    it('subscribe delivers a message event on send', async () => {
+      const a = await make();
+      const seen: MessageEvent[] = [];
+      const off = a.subscribe(opts.seededThreadId, (e) => seen.push(e));
+      await a.send(opts.seededThreadId, 'live one');
+      off();
+      const msgs = seen.filter((e) => e.kind === 'message');
+      expect(msgs.length).toBeGreaterThan(0);
+    });
+
+    it('unsubscribe stops delivery', async () => {
+      const a = await make();
+      const seen: MessageEvent[] = [];
+      const off = a.subscribe(opts.seededThreadId, (e) => seen.push(e));
+      off();
+      await a.send(opts.seededThreadId, 'should not be heard');
+      expect(seen).toHaveLength(0);
+    });
+
+    it('unsubscribe is idempotent', async () => {
+      const a = await make();
+      const off = a.subscribe(opts.seededThreadId, () => {});
+      off();
+      expect(() => off()).not.toThrow();
+    });
+
+    it('openThread returns a thread id', async () => {
+      const a = await make();
+      const { threadId } = await a.openThread({ participantIds: opts.openWith });
+      expect(typeof threadId).toBe('string');
+      expect(threadId.length).toBeGreaterThan(0);
+    });
+
+    it('markRead resolves', async () => {
+      const a = await make();
+      const m = await a.send(opts.seededThreadId, 'read me');
+      await expect(a.markRead(opts.seededThreadId, m.id)).resolves.toBeUndefined();
+    });
+
+    it('sendTyping does not throw', async () => {
+      const a = await make();
+      expect(() => a.sendTyping(opts.seededThreadId)).not.toThrow();
+    });
+  });
+}
+```
+
+- [ ] **Step 2: Verify it typechecks**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui typecheck`
+Expected: no errors. (The suite has no adapter to run against yet — that is Task 5.)
+
+- [ ] **Step 3: Commit**
+
+```bash
+git add packages/iios-messaging-ui/src/conformance.ts
+git commit -m "feat: add adapter conformance suite"
+```
+
+---
+
+### Task 5: Mock adapter
+
+**Files:**
+- Create: `packages/iios-messaging-ui/src/adapters/mock.ts`
+- Test: `packages/iios-messaging-ui/src/conformance.test.ts`
+
+Ported from the CRM's `MOCK_STORE`, with one deliberate change: **the store is per-instance, not module-level.** The CRM's module-level `Map` leaks state between tests. Fixtures match the CRM's so demo mode looks identical after migration.
+
+- [ ] **Step 1: Write the failing test**
+
+Create `packages/iios-messaging-ui/src/conformance.test.ts`:
+
+```ts
+import { runAdapterConformance } from './conformance';
+import { MockAdapter } from './adapters/mock';
+
+runAdapterConformance({
+  makeAdapter: () => new MockAdapter(),
+  seededThreadId: 'th_mock_1',
+  openWith: ['pp_sofia'],
+});
+```
+
+- [ ] **Step 2: Run test to verify it fails**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test`
+Expected: FAIL — "Failed to resolve import ./adapters/mock".
+
+- [ ] **Step 3: Write the implementation**
+
+Create `packages/iios-messaging-ui/src/adapters/mock.ts`:
+
+```ts
+import type { MessagingAdapter } from '../adapter';
+import type {
+  Attachment,
+  Conversation,
+  Membership,
+  Message,
+  MessageEvent,
+  Person,
+  SendOpts,
+  Unsubscribe,
+} from '../types';
+
+const ME = 'me';
+
+export const MOCK_PEOPLE: Person[] = [
+  { id: 'pp_sofia', name: 'Sofia Ramirez', kind: 'staff' },
+  { id: 'pp_dan', name: 'Dan Whitaker', kind: 'staff' },
+  { id: 'pp_priya', name: 'Priya Nair', kind: 'staff' },
+  { id: 'cust_acme', name: 'Acme Roofing (Client)', kind: 'customer' },
+  { id: 'cust_globex', name: 'Globex Homes (Client)', kind: 'customer' },
+];
+
+interface MockThread {
+  threadId: string;
+  membership: Membership;
+  subject: string | null;
+  participants: string[];
+  messages: Message[];
+}
+
+const nameById = new Map(MOCK_PEOPLE.map((p) => [p.id, p.name]));
+
+/**
+ * In-memory adapter for demos and tests. State is PER INSTANCE — the CRM's version
+ * used a module-level Map, which leaks between tests. Each `new MockAdapter()` is
+ * fully isolated.
+ */
+export class MockAdapter implements MessagingAdapter {
+  private seq = 100;
+  private threads = new Map<string, MockThread>();
+  private listeners = new Map<string, Set<(e: MessageEvent) => void>>();
+
+  constructor(private readonly now: () => string = () => new Date().toISOString()) {
+    this.threads.set('th_mock_1', {
+      threadId: 'th_mock_1',
+      membership: 'dm',
+      subject: null,
+      participants: [ME, 'pp_sofia'],
+      messages: [
+        {
+          id: 'm1',
+          actorId: 'pp_sofia',
+          text: 'Can you review the Henderson estimate?',
+          at: this.now(),
+          reactions: [],
+        },
+      ],
+    });
+    this.threads.set('th_mock_2', {
+      threadId: 'th_mock_2',
+      membership: 'group',
+      subject: 'Storm response — East side',
+      participants: [ME, 'pp_dan', 'pp_priya'],
+      messages: [
+        { id: 'm2', actorId: 'pp_dan', text: 'Crew is rolling out at 7.', at: this.now(), reactions: [] },
+      ],
+    });
+  }
+
+  currentActorId(): string {
+    return ME;
+  }
+
+  async listConversations(): Promise<Conversation[]> {
+    return [...this.threads.values()].map((t) => {
+      const last = t.messages[t.messages.length - 1];
+      const others = t.participants.filter((p) => p !== ME);
+      return {
+        threadId: t.threadId,
+        title: t.subject || others.map((id) => nameById.get(id) ?? id).join(', ') || 'Conversation',
+        subject: t.subject,
+        membership: t.membership,
+        participants: t.participants,
+        unread: 0,
+        ...(last ? { lastMessage: last.text, lastAt: last.at } : {}),
+      };
+    });
+  }
+
+  async openThread(p: { participantIds: string[]; membership?: Membership; subject?: string }): Promise<{ threadId: string }> {
+    const membership = p.membership ?? (p.participantIds.length === 1 ? 'dm' : 'group');
+    const threadId = `th_mock_${this.seq++}`;
+    this.threads.set(threadId, {
+      threadId,
+      membership,
+      subject: p.subject ?? null,
+      participants: [ME, ...p.participantIds],
+      messages: [],
+    });
+    return { threadId };
+  }
+
+  async history(threadId: string): Promise<Message[]> {
+    return this.threads.get(threadId)?.messages ?? [];
+  }
+
+  async send(threadId: string, content: string, opts?: SendOpts): Promise<Message> {
+    const t = this.threads.get(threadId);
+    if (!t) throw new Error(`Unknown thread: ${threadId}`);
+    const message: Message = {
+      id: `m_${this.seq++}`,
+      actorId: ME,
+      text: content,
+      at: this.now(),
+      reactions: [],
+      ...(opts?.parentInteractionId ? { parentInteractionId: opts.parentInteractionId } : {}),
+      ...(opts?.attachment ? { attachment: opts.attachment } : {}),
+    };
+    t.messages = [...t.messages, message];
+    this.emit(threadId, { kind: 'message', message });
+    return message;
+  }
+
+  async react(threadId: string, messageId: string, emoji: string): Promise<void> {
+    const t = this.threads.get(threadId);
+    if (!t) return;
+    let next: Message | undefined;
+    t.messages = t.messages.map((m) => {
+      if (m.id !== messageId) return m;
+      const existing = (m.reactions ?? []).find((r) => r.emoji === emoji);
+      const reactions = existing
+        ? (m.reactions ?? []).filter((r) => r.emoji !== emoji)
+        : [...(m.reactions ?? []), { emoji, count: 1, mine: true }];
+      next = { ...m, reactions };
+      return next;
+    });
+    if (next) this.emit(threadId, { kind: 'reaction', messageId, reactions: next.reactions ?? [] });
+  }
+
+  async upload(file: File): Promise<Attachment> {
+    return { url: `mock://uploads/${file.name}`, mime: file.type, name: file.name };
+  }
+
+  subscribe(threadId: string, cb: (e: MessageEvent) => void): Unsubscribe {
+    if (!this.listeners.has(threadId)) this.listeners.set(threadId, new Set());
+    this.listeners.get(threadId)!.add(cb);
+    return () => {
+      this.listeners.get(threadId)?.delete(cb);
+    };
+  }
+
+  sendTyping(): void {
+    // No-op: nobody is typing back in a mock.
+  }
+
+  async markRead(): Promise<void> {
+    // No-op: the mock has no second party to report a read.
+  }
+
+  isConnected(): boolean {
+    return true;
+  }
+
+  private emit(threadId: string, e: MessageEvent): void {
+    this.listeners.get(threadId)?.forEach((cb) => cb(e));
+  }
+}
+```
+
+- [ ] **Step 4: Run test to verify it passes**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test`
+Expected: PASS — 12 conformance tests green.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add packages/iios-messaging-ui/src/adapters/mock.ts packages/iios-messaging-ui/src/conformance.test.ts
+git commit -m "feat: add MockAdapter passing the conformance suite"
+```
+
+---
+
+### Task 6: MessagingProvider
+
+**Files:**
+- Create: `packages/iios-messaging-ui/src/provider.tsx`
+- Test: `packages/iios-messaging-ui/src/provider.test.tsx`
+
+- [ ] **Step 1: Write the failing test**
+
+Create `packages/iios-messaging-ui/src/provider.test.tsx`:
+
+```tsx
+import { describe, it, expect } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import { MessagingProvider, useAdapter } from './provider';
+import { MockAdapter } from './adapters/mock';
+
+function ShowActor() {
+  const adapter = useAdapter();
+  return <span>{adapter.currentActorId()}</span>;
+}
+
+describe('MessagingProvider', () => {
+  it('supplies the injected adapter to descendants', () => {
+    render(
+      <MessagingProvider adapter={new MockAdapter()}>
+        <ShowActor />
+      </MessagingProvider>,
+    );
+    expect(screen.getByText('me')).toBeDefined();
+  });
+
+  it('throws a helpful error when a hook is used outside the provider', () => {
+    // React logs the error boundary trace; that noise is expected.
+    expect(() => render(<ShowActor />)).toThrow(/useAdapter must be used within a <MessagingProvider>/);
+  });
+});
+```
+
+- [ ] **Step 2: Run test to verify it fails**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test`
+Expected: FAIL — "Failed to resolve import ./provider".
+
+- [ ] **Step 3: Write the implementation**
+
+Create `packages/iios-messaging-ui/src/provider.tsx`:
+
+```tsx
+import { createContext, useContext, type ReactNode } from 'react';
+import type { MessagingAdapter } from './adapter';
+
+const AdapterContext = createContext<MessagingAdapter | null>(null);
+
+export function MessagingProvider({
+  adapter,
+  children,
+}: {
+  adapter: MessagingAdapter;
+  children: ReactNode;
+}) {
+  return <AdapterContext.Provider value={adapter}>{children}</AdapterContext.Provider>;
+}
+
+/** Access the host-injected adapter. Throws outside a provider — a missing provider is
+ *  a wiring bug, and failing loudly beats a confusing null-deref three layers down. */
+export function useAdapter(): MessagingAdapter {
+  const adapter = useContext(AdapterContext);
+  if (!adapter) throw new Error('useAdapter must be used within a <MessagingProvider>');
+  return adapter;
+}
+```
+
+- [ ] **Step 4: Run test to verify it passes**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test`
+Expected: PASS, 2 new tests.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add packages/iios-messaging-ui/src/provider.tsx packages/iios-messaging-ui/src/provider.test.tsx
+git commit -m "feat: add MessagingProvider and useAdapter"
+```
+
+---
+
+### Task 7: useConversations
+
+**Files:**
+- Create: `packages/iios-messaging-ui/src/hooks/use-conversations.ts`
+- Test: `packages/iios-messaging-ui/src/hooks/use-conversations.test.tsx`
+
+- [ ] **Step 1: Write the failing test**
+
+Create `packages/iios-messaging-ui/src/hooks/use-conversations.test.tsx`:
+
+```tsx
+import { describe, it, expect, vi } from 'vitest';
+import { renderHook, waitFor, act } from '@testing-library/react';
+import type { ReactNode } from 'react';
+import { MessagingProvider } from '../provider';
+import { MockAdapter } from '../adapters/mock';
+import { useConversations } from './use-conversations';
+import type { MessagingAdapter } from '../adapter';
+
+const wrap = (adapter: MessagingAdapter) =>
+  function Wrapper({ children }: { children: ReactNode }) {
+    return <MessagingProvider adapter={adapter}>{children}</MessagingProvider>;
+  };
+
+describe('useConversations', () => {
+  it('starts loading, then resolves the adapter list', async () => {
+    const { result } = renderHook(() => useConversations(), { wrapper: wrap(new MockAdapter()) });
+    expect(result.current.loading).toBe(true);
+
+    await waitFor(() => expect(result.current.loading).toBe(false));
+    expect(result.current.conversations).toHaveLength(2);
+    expect(result.current.conversations[0]!.threadId).toBe('th_mock_1');
+    expect(result.current.error).toBeNull();
+  });
+
+  it('surfaces adapter failure as error state and never throws', async () => {
+    const adapter = new MockAdapter();
+    vi.spyOn(adapter, 'listConversations').mockRejectedValue(new Error('data door down'));
+
+    const { result } = renderHook(() => useConversations(), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+    expect(result.current.error).toBe('data door down');
+    expect(result.current.conversations).toEqual([]);
+  });
+
+  it('refetch picks up newly opened threads', async () => {
+    const adapter = new MockAdapter();
+    const { result } = renderHook(() => useConversations(), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.conversations).toHaveLength(2));
+
+    await act(async () => {
+      await adapter.openThread({ participantIds: ['pp_dan'] });
+    });
+    await act(async () => {
+      result.current.refetch();
+    });
+
+    await waitFor(() => expect(result.current.conversations).toHaveLength(3));
+  });
+});
+```
+
+- [ ] **Step 2: Run test to verify it fails**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test`
+Expected: FAIL — "Failed to resolve import ./use-conversations".
+
+- [ ] **Step 3: Write the implementation**
+
+Create `packages/iios-messaging-ui/src/hooks/use-conversations.ts`:
+
+```ts
+import { useCallback, useEffect, useState } from 'react';
+import { useAdapter } from '../provider';
+import type { Conversation } from '../types';
+
+export interface ConversationsState {
+  conversations: Conversation[];
+  loading: boolean;
+  error: string | null;
+  refetch: () => void;
+}
+
+export function useConversations(): ConversationsState {
+  const adapter = useAdapter();
+  const [conversations, setConversations] = useState<Conversation[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [nonce, setNonce] = useState(0);
+
+  useEffect(() => {
+    let alive = true;
+    setLoading(true);
+    adapter
+      .listConversations()
+      .then((list) => {
+        if (!alive) return;
+        setConversations(list);
+        setError(null);
+      })
+      .catch((e: unknown) => {
+        if (!alive) return;
+        setError(e instanceof Error ? e.message : String(e));
+        setConversations([]);
+      })
+      .finally(() => {
+        if (alive) setLoading(false);
+      });
+    return () => {
+      alive = false;
+    };
+  }, [adapter, nonce]);
+
+  const refetch = useCallback(() => setNonce((n) => n + 1), []);
+
+  return { conversations, loading, error, refetch };
+}
+```
+
+- [ ] **Step 4: Run test to verify it passes**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test`
+Expected: PASS, 3 new tests.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add packages/iios-messaging-ui/src/hooks
+git commit -m "feat: add useConversations hook"
+```
+
+---
+
+### Task 8: useMessages
+
+**Files:**
+- Create: `packages/iios-messaging-ui/src/hooks/use-messages.ts`
+- Test: `packages/iios-messaging-ui/src/hooks/use-messages.test.tsx`
+
+The heart of the SDK. Three behaviours matter most: **ownership before you speak** (the CRM bug), **optimistic send with rollback**, and **event reconciliation by id** (no duplicates when the echo arrives).
+
+- [ ] **Step 1: Write the failing test**
+
+Create `packages/iios-messaging-ui/src/hooks/use-messages.test.tsx`:
+
+```tsx
+import { describe, it, expect, vi } from 'vitest';
+import { renderHook, waitFor, act } from '@testing-library/react';
+import type { ReactNode } from 'react';
+import { MessagingProvider } from '../provider';
+import { MockAdapter } from '../adapters/mock';
+import { useMessages } from './use-messages';
+import type { MessagingAdapter } from '../adapter';
+
+const wrap = (adapter: MessagingAdapter) =>
+  function Wrapper({ children }: { children: ReactNode }) {
+    return <MessagingProvider adapter={adapter}>{children}</MessagingProvider>;
+  };
+
+describe('useMessages', () => {
+  it('loads history for the thread', async () => {
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(new MockAdapter()) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+    expect(result.current.messages).toHaveLength(1);
+    expect(result.current.messages[0]!.text).toBe('Can you review the Henderson estimate?');
+  });
+
+  // REGRESSION: the CRM inferred actor identity by scanning for a sent message, so
+  // before you had spoken in a thread EVERY message rendered as not-yours.
+  it('marks ownership correctly before the user has sent anything', async () => {
+    const adapter = new MockAdapter();
+    await adapter.send('th_mock_1', 'an earlier message of mine');
+
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.messages).toHaveLength(2));
+
+    // Never sent anything via the hook — ownership still resolves from currentActorId().
+    expect(result.current.messages[0]!.mine).toBe(false); // from pp_sofia
+    expect(result.current.messages[1]!.mine).toBe(true); // from me
+  });
+
+  it('appends an optimistic message immediately on send', async () => {
+    const adapter = new MockAdapter();
+    let release!: () => void;
+    vi.spyOn(adapter, 'send').mockImplementation(
+      () => new Promise((res) => { release = () => res({ id: 'srv_1', actorId: 'me', text: 'hi', at: '2026-07-17T10:00:00.000Z' }); }),
+    );
+
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+
+    act(() => { void result.current.send('hi'); });
+
+    await waitFor(() => expect(result.current.messages).toHaveLength(2));
+    expect(result.current.messages[1]!.pending).toBe(true);
+    expect(result.current.messages[1]!.mine).toBe(true);
+
+    await act(async () => { release(); });
+    await waitFor(() => expect(result.current.messages[1]!.pending).toBeFalsy());
+  });
+
+  it('rolls back the optimistic message and reports error when send fails', async () => {
+    const adapter = new MockAdapter();
+    vi.spyOn(adapter, 'send').mockRejectedValue(new Error('offline'));
+
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+
+    await act(async () => {
+      await expect(result.current.send('doomed')).rejects.toThrow('offline');
+    });
+
+    expect(result.current.messages).toHaveLength(1);
+    expect(result.current.messages.some((m) => m.text === 'doomed')).toBe(false);
+    expect(result.current.error).toBe('offline');
+  });
+
+  it('does not duplicate a message when the transport echoes it back', async () => {
+    const adapter = new MockAdapter();
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+
+    // MockAdapter.send emits a 'message' event AND resolves with the same message.
+    await act(async () => { await result.current.send('echo once'); });
+
+    expect(result.current.messages.filter((m) => m.text === 'echo once')).toHaveLength(1);
+  });
+
+  it('collects typing user ids from subscribe events', async () => {
+    const adapter = new MockAdapter();
+    let emit!: (userId: string) => void;
+    vi.spyOn(adapter, 'subscribe').mockImplementation((_t, cb) => {
+      emit = (userId) => cb({ kind: 'typing', userId });
+      return () => {};
+    });
+
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+
+    act(() => emit('pp_sofia'));
+    expect(result.current.typingUserIds).toEqual(['pp_sofia']);
+  });
+
+  it('unsubscribes on unmount', async () => {
+    const adapter = new MockAdapter();
+    const off = vi.fn();
+    vi.spyOn(adapter, 'subscribe').mockReturnValue(off);
+
+    const { unmount, result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+    unmount();
+
+    expect(off).toHaveBeenCalled();
+  });
+});
+```
+
+- [ ] **Step 2: Run test to verify it fails**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test`
+Expected: FAIL — "Failed to resolve import ./use-messages".
+
+- [ ] **Step 3: Write the implementation**
+
+Create `packages/iios-messaging-ui/src/hooks/use-messages.ts`:
+
+```ts
+import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
+import { useAdapter } from '../provider';
+import { isOwnMessage } from '../types';
+import type { Message, SendOpts } from '../types';
+
+const TYPING_TTL_MS = 3500;
+
+export interface UiMessage extends Message {
+  mine: boolean;
+}
+
+export interface MessagesState {
+  messages: UiMessage[];
+  loading: boolean;
+  error: string | null;
+  send: (content: string, opts?: SendOpts) => Promise<void>;
+  react: (messageId: string, emoji: string) => Promise<void>;
+  typingUserIds: string[];
+  seenIds: Set<string>;
+  sendTyping: () => void;
+  canReact: boolean;
+  canUpload: boolean;
+}
+
+let optimisticSeq = 0;
+
+export function useMessages(threadId: string | null): MessagesState {
+  const adapter = useAdapter();
+  const [raw, setRaw] = useState<Message[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [typing, setTyping] = useState<Record<string, number>>({});
+  const [seenIds, setSeenIds] = useState<Set<string>>(new Set());
+  const [, forceTick] = useState(0);
+
+  const currentActorId = adapter.currentActorId();
+  const actorRef = useRef(currentActorId);
+  actorRef.current = currentActorId;
+
+  // Load history, then subscribe. Reconciliation is by message id, so an echoed
+  // send never duplicates the optimistic row.
+  useEffect(() => {
+    if (!threadId) {
+      setRaw([]);
+      setLoading(false);
+      return;
+    }
+    let alive = true;
+    setLoading(true);
+    setRaw([]);
+    setSeenIds(new Set());
+    setTyping({});
+
+    adapter
+      .history(threadId)
+      .then((h) => {
+        if (alive) {
+          setRaw(h);
+          setError(null);
+        }
+      })
+      .catch((e: unknown) => {
+        if (alive) setError(e instanceof Error ? e.message : String(e));
+      })
+      .finally(() => {
+        if (alive) setLoading(false);
+      });
+
+    const off = adapter.subscribe(threadId, (e) => {
+      if (!alive) return;
+      switch (e.kind) {
+        case 'message':
+          setRaw((l) => (l.some((m) => m.id === e.message.id) ? l : [...l, e.message]));
+          break;
+        case 'typing':
+          if (e.userId !== actorRef.current) {
+            setTyping((t) => ({ ...t, [e.userId]: Date.now() + TYPING_TTL_MS }));
+          }
+          break;
+        case 'receipt':
+          // Only the OTHER side reading my message counts as "seen".
+          if (e.actorId !== actorRef.current) {
+            setSeenIds((s) => (s.has(e.messageId) ? s : new Set(s).add(e.messageId)));
+          }
+          break;
+        case 'reaction':
+          setRaw((l) => l.map((m) => (m.id === e.messageId ? { ...m, reactions: e.reactions } : m)));
+          break;
+      }
+    });
+
+    return () => {
+      alive = false;
+      off();
+    };
+  }, [adapter, threadId]);
+
+  const messages: UiMessage[] = useMemo(
+    () => raw.map((m) => ({ ...m, mine: isOwnMessage(m, currentActorId) })),
+    [raw, currentActorId],
+  );
+
+  const send = useCallback(
+    async (content: string, opts?: SendOpts) => {
+      if (!threadId) return;
+      const tempId = `optimistic_${optimisticSeq++}`;
+      const optimistic: Message = {
+        id: tempId,
+        actorId: actorRef.current,
+        text: content,
+        at: new Date().toISOString(),
+        pending: true,
+        reactions: [],
+        ...(opts?.parentInteractionId ? { parentInteractionId: opts.parentInteractionId } : {}),
+        ...(opts?.attachment ? { attachment: opts.attachment } : {}),
+      };
+      setRaw((l) => [...l, optimistic]);
+
+      try {
+        const saved = await adapter.send(threadId, content, opts);
+        setError(null);
+        // Replace the optimistic row with the server's. If the subscribe echo already
+        // added the real message, just drop the optimistic one.
+        setRaw((l) => {
+          const withoutTemp = l.filter((m) => m.id !== tempId);
+          return withoutTemp.some((m) => m.id === saved.id) ? withoutTemp : [...withoutTemp, saved];
+        });
+      } catch (e: unknown) {
+        setRaw((l) => l.filter((m) => m.id !== tempId));
+        setError(e instanceof Error ? e.message : String(e));
+        throw e;
+      }
+    },
+    [adapter, threadId],
+  );
+
+  const react = useCallback(
+    async (messageId: string, emoji: string) => {
+      if (!threadId || !adapter.react) return;
+      await adapter.react(threadId, messageId, emoji);
+    },
+    [adapter, threadId],
+  );
+
+  const sendTyping = useCallback(() => {
+    if (threadId) adapter.sendTyping(threadId);
+  }, [adapter, threadId]);
+
+  // Report my read of the newest message (drives the other side's "seen" tick).
+  useEffect(() => {
+    if (!threadId || raw.length === 0) return;
+    const last = raw[raw.length - 1]!;
+    if (last.pending) return;
+    void adapter.markRead(threadId, last.id).catch(() => {});
+  }, [adapter, threadId, raw]);
+
+  const typingUserIds = useMemo(() => {
+    const now = Date.now();
+    return Object.entries(typing)
+      .filter(([, exp]) => exp > now)
+      .map(([u]) => u);
+  }, [typing]);
+
+  // Expire stale typing entries by re-evaluating after the TTL.
+  useEffect(() => {
+    if (typingUserIds.length === 0) return;
+    const t = setTimeout(() => forceTick((n) => n + 1), TYPING_TTL_MS);
+    return () => clearTimeout(t);
+  }, [typingUserIds.length, typing]);
+
+  // Only my messages that the other side has read.
+  const seenMine = useMemo(() => {
+    const out = new Set<string>();
+    for (const id of seenIds) if (messages.some((m) => m.id === id && m.mine)) out.add(id);
+    return out;
+  }, [seenIds, messages]);
+
+  return {
+    messages,
+    loading,
+    error,
+    send,
+    react,
+    typingUserIds,
+    seenIds: seenMine,
+    sendTyping,
+    canReact: typeof adapter.react === 'function',
+    canUpload: typeof adapter.upload === 'function',
+  };
+}
+```
+
+- [ ] **Step 4: Run test to verify it passes**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test`
+Expected: PASS, 7 new tests.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add packages/iios-messaging-ui/src/hooks/use-messages.ts packages/iios-messaging-ui/src/hooks/use-messages.test.tsx
+git commit -m "feat: add useMessages hook with explicit ownership and optimistic send"
+```
+
+---
+
+### Task 9: Public barrel + transport-freedom enforcement
+
+**Files:**
+- Modify: `packages/iios-messaging-ui/src/index.ts`
+- Create: `packages/iios-messaging-ui/src/boundary.test.ts`
+- Modify: `scripts/check-import-boundary.mjs:22` (add the new package to `ALLOWED`)
+
+The repo's boundary script is **package-level**, so it cannot express "core must not import kernel-client, but `adapters/kernel` may". That distinction is this SDK's core premise, so it gets its own test.
+
+- [ ] **Step 1: Write the failing test**
+
+Create `packages/iios-messaging-ui/src/boundary.test.ts`:
+
+```ts
+import { describe, it, expect } from 'vitest';
+import { readdirSync, readFileSync, statSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { join } from 'node:path';
+
+// This package is ESM ("type": "module") — __dirname does not exist here.
+const SRC = fileURLToPath(new URL('.', import.meta.url));
+const ADAPTERS = join(SRC, 'adapters');
+
+function tsFilesIn(dir: string): string[] {
+  const out: string[] = [];
+  for (const entry of readdirSync(dir)) {
+    const full = join(dir, entry);
+    if (statSync(full).isDirectory()) out.push(...tsFilesIn(full));
+    else if (/\.tsx?$/.test(full)) out.push(full);
+  }
+  return out;
+}
+
+// The whole premise of this package: core renders, adapters transport. If core ever
+// imports a transport, an app on a different backend pays for socket code it cannot
+// use — which is exactly how iios-message-web welded itself to MessageSocket.
+describe('transport boundary', () => {
+  const coreFiles = tsFilesIn(SRC).filter((f) => !f.startsWith(ADAPTERS) && !/\.test\.tsx?$/.test(f));
+
+  it('has core files to check', () => {
+    expect(coreFiles.length).toBeGreaterThan(0);
+  });
+
+  it('core never imports a transport package', () => {
+    const offenders: string[] = [];
+    for (const file of coreFiles) {
+      const content = readFileSync(file, 'utf8');
+      if (/@insignia\/iios-kernel-client|socket\.io|@abe-kap\/appshell-sdk/.test(content)) {
+        offenders.push(file.replace(SRC, 'src'));
+      }
+    }
+    expect(offenders).toEqual([]);
+  });
+});
+```
+
+- [ ] **Step 2: Run test to verify it passes**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test`
+Expected: PASS. (This test guards a property that already holds — it fails loudly in Plan 3 if someone imports the kernel from core.)
+
+- [ ] **Step 3: Write the public barrel**
+
+Replace `packages/iios-messaging-ui/src/index.ts`:
+
+```ts
+// Public API. Components land in Plan 2; adapters/kernel in Plan 3.
+//
+// `runAdapterConformance` is deliberately NOT exported here — it imports vitest and
+// ships from the './conformance' subpath so consumers never pull a test runner into
+// their production bundle.
+export { MessagingProvider, useAdapter } from './provider';
+export { useConversations } from './hooks/use-conversations';
+export { useMessages } from './hooks/use-messages';
+export { isOwnMessage } from './types';
+
+export type { MessagingAdapter } from './adapter';
+export type { ConversationsState } from './hooks/use-conversations';
+export type { MessagesState, UiMessage } from './hooks/use-messages';
+export type {
+  Attachment,
+  Conversation,
+  Membership,
+  Message,
+  MessageEvent,
+  Person,
+  Reaction,
+  SendOpts,
+  Unsubscribe,
+} from './types';
+```
+
+- [ ] **Step 4: Register the package in the repo's import-boundary law**
+
+In `scripts/check-import-boundary.mjs`, add this entry to the `ALLOWED` map (after the `'@insignia/iios-message-web'` line):
+
+```js
+  // Core is transport-free; only ./adapters/kernel may import the kernel client.
+  // This map is package-level and cannot express that subpath rule — the finer
+  // constraint is enforced by packages/iios-messaging-ui/src/boundary.test.ts.
+  '@insignia/iios-messaging-ui': ['@insignia/iios-kernel-client'],
+```
+
+- [ ] **Step 5: Verify the boundary law still passes**
+
+Run: `pnpm boundary`
+Expected: `✓ import-boundary: OK`
+
+- [ ] **Step 6: Verify the full package**
+
+Run: `pnpm --filter @insignia/iios-messaging-ui test && pnpm --filter @insignia/iios-messaging-ui typecheck && pnpm --filter @insignia/iios-messaging-ui build`
+Expected: all tests PASS; no type errors; `dist/index.js`, `dist/index.d.ts`, `dist/adapters/mock.js`, `dist/conformance.js` produced.
+
+- [ ] **Step 6b: Verify the main entry does not drag in vitest**
+
+Run: `grep -c vitest packages/iios-messaging-ui/dist/index.js || echo "clean"`
+Expected: `clean` (grep finds nothing and exits 1). If this prints a number, `conformance.ts` leaked into the main barrel — remove the re-export from `src/index.ts`.
+
+Run: `grep -rE "iios-kernel-client|socket\.io" packages/iios-messaging-ui/dist/index.js || echo "transport-free"`
+Expected: `transport-free`.
+
+- [ ] **Step 7: Verify the root test suite is unaffected**
+
+Run: `pnpm test`
+Expected: the root suite passes exactly as before. Its `include` matches only `.ts`, so this package's `.tsx` tests are not picked up there — intentional, since root provisions Postgres. The package's tests run via its own `test` script.
+
+- [ ] **Step 8: Commit**
+
+```bash
+git add packages/iios-messaging-ui/src/index.ts packages/iios-messaging-ui/src/boundary.test.ts scripts/check-import-boundary.mjs
+git commit -m "feat: export messaging-ui public API and enforce transport boundary"
+```
+
+---
+
+## Done criteria
+
+- `pnpm --filter @insignia/iios-messaging-ui test` — all green (33 tests as shipped).
+- `pnpm boundary` — OK.
+- `pnpm test` at root — unchanged.
+- The package builds to ESM with types and has **zero runtime dependencies**.
+- A host can already drive messaging headlessly: `MessagingProvider` + `MockAdapter` + hooks.
+
+## Post-implementation corrections (2026-07-18)
+
+Executed via subagent-driven development on branch `feat/inbox-owner-interest`. Code review during Tasks 5 and 8 caught defects in the code blocks **above** — the shipped code diverges from the plan text in these ways, and Plan 3 should treat the committed source (not the Task 8 listing above) as authoritative:
+
+- **`useMessages` typing expiry** — the plan used `forceTick((n) => n + 1)` to expire stale typing entries. That is a no-op: the `typingUserIds` memo is keyed on `[typing]`, so an unrelated state bump returns the cached array and the indicator sticks forever. Shipped code uses `setTimeout(() => setTyping((p) => ({ ...p })), TYPING_TTL_MS)` (a new `typing` reference forces the memo to recompute with a fresh `now`). `forceTick` state removed entirely.
+- **`useMessages` history race** — the plan's `.then((h) => setRaw(h))` clobbers live messages that arrive via `subscribe` while `history()` is still in flight (silent data loss on any async transport; the sync MockAdapter can't show it). Shipped code merges by id: `setRaw((live) => { const histIds = new Set(h.map(m => m.id)); const extras = live.filter(m => !histIds.has(m.id)); return extras.length ? [...h, ...extras] : h; })`. Guarded by the test "keeps a live message that arrives before history resolves" (verified to fail if the merge is reverted).
+- **`useMessages` markRead** — re-keyed from `[adapter, threadId, raw]` (fired on every array churn, incl. reactions) to a derived `lastReadableId` (newest non-pending id), so it fires only when the read frontier actually moves.
+- **`useMessages` error reset** — `setError(null)` added to the thread-switch reset block (plan left a stale error banner across thread switches).
+- **`MockAdapter`** — `history()` and `listConversations().participants` now return copies (plan leaked the live internal arrays); constructor calls `now()` once for both seed messages.
+- **`boundary.test.ts`** — carries a `// @vitest-environment node` directive on line 1. jsdom overrides the global `URL` constructor, which breaks `fileURLToPath(new URL('.', import.meta.url))`; a filesystem test must run in node.
+
+**Known limitation deferred to Plan 3 (issue I2):** `useMessages` reads `adapter.currentActorId()` per-render but nothing makes it reactive. If a real adapter's identity resolves from `null` to a value with no intervening React state change, ownership stays wrong until an incidental re-render — and an optimistic message stamped while identity is `null` renders as not-mine. The MockAdapter never has null identity, so this does not manifest in the foundation. Plan 3 must decide how the real adapter exposes identity reactively (e.g. an `onActorIdChange` subscription on the interface, or the host re-rendering the provider when auth resolves) rather than relying on incidental re-renders.
+
+## What Plan 2 adds
+
+Components (`ConversationList`, `ThreadView`, `Composer`, `MessageBubble`, `Messenger`), the SDK's own internal primitives (the CRM's `Avatar`/`Btn`/`Icon` cannot be imported — they live in `lynkeduppro-crm/src/components/dashboard/ui.tsx`), `styles.css` with the `--msg-*` token contract, and the `classNames` slot map.
+
+## What Plan 3 adds
+
+`./adapters/kernel` (wrapping `iios-kernel-client`, running the conformance suite), `CrmMessagingAdapter` in the CRM repo (data door + socket + 4s poll fallback, also running conformance), attachments end-to-end, and the CRM migration that deletes `messenger.tsx`.
+
+Both adapters verify themselves with `import { runAdapterConformance } from '@insignia/iios-messaging-ui/conformance'`. Plan 3 must add `@insignia/iios-kernel-client` to this package's `dependencies` and to the `tsup` `entry` + `external` lists — and `src/boundary.test.ts` will fail if that import reaches core rather than staying inside `src/adapters/`.
+
+**Strengthen the safety nets before writing the kernel adapter** (from the final foundation review — the current versions are adequate for the mock but too weak to catch a broken real adapter):
+
+- **Expand `runAdapterConformance`.** Today it only exercises the happy `message` path. It does NOT test the optional methods (`react`/`upload`/`isConnected`), **subscribe thread-isolation** (an adapter that leaks every thread's events to every subscriber would pass yet break the UI), or the `receipt`/`reaction`/`typing` event kinds. Since conformance IS the safety net for the real kernel adapter, add these cases first.
+- **Convert `boundary.test.ts` from a denylist to an allowlist.** It currently greps core for three transport strings (`iios-kernel-client|socket.io|@abe-kap/appshell-sdk`); a core file importing a *different* transport (`ws`, `pusher`, raw WebSocket) would slip through, and the root `pnpm boundary` allowlist only governs at package granularity. Once `adapters/kernel` exists, assert core imports only `react` + relative paths.
+- **Also address the deferred I2 (reactive identity)** noted under Post-implementation corrections above, and resolve the two Plan-2 notes: emit `dist/styles.css` so the exports entry resolves, and decide whether `react()` failures should populate `error` (today only `send()` does).
+
+## CI note for whoever wires it
+
+Root `pnpm test` does not run this package's tests. CI must also run:
+
+```bash
+pnpm --filter @insignia/iios-messaging-ui test
+```
+
+The alternative — folding `.tsx` + jsdom into the root config — would make every UI test wait on Postgres provisioning. Not worth it.
diff --git a/iios-0.0.0.tgz b/iios-0.0.0.tgz
new file mode 100644
index 0000000..970695d
Binary files /dev/null and b/iios-0.0.0.tgz differ
diff --git a/packages/iios-kernel-client/src/rest.ts b/packages/iios-kernel-client/src/rest.ts
index 5b04608..dd1234d 100644
--- a/packages/iios-kernel-client/src/rest.ts
+++ b/packages/iios-kernel-client/src/rest.ts
@@ -1,5 +1,5 @@
 import type { IngestInteractionRequest } from '@insignia/iios-contracts';
-import type { Message, InboxItem, InboxState, Ticket, TicketState, CallbackRequest, RouteBinding, RouteDecision, AiArtifact, AiJobResult, Meeting, MeetingActionItem, ThreadSummary, SavedItem, LoginResult } from './types';
+import type { Message, InboxItem, InboxState, Ticket, TicketState, CallbackRequest, RouteBinding, RouteDecision, AiArtifact, AiJobResult, Meeting, MeetingActionItem, ThreadSummary, DiscoveredThread, SavedItem, LoginResult } from './types';
 
 export interface RestConfig {
   serviceUrl: string;
@@ -103,6 +103,27 @@ export class RestClient {
     return this.post<{ threadId: string }>('/v1/threads', opts);
   }
 
+  /**
+   * Discover threads across your scope matching an opaque metadata filter (e.g. browse public
+   * channels: `{ membership: 'channel', visibility: 'public' }`). Returns ones you have NOT joined
+   * too, each flagged `joined`.
+   */
+  async discoverThreads(filter?: { metadata?: Record<string, string> }): Promise<DiscoveredThread[]> {
+    const qs = filter?.metadata
+      ? '?' + Object.entries(filter.metadata).map(([k, v]) => `metadata[${encodeURIComponent(k)}]=${encodeURIComponent(v)}`).join('&')
+      : '';
+    const r = await fetch(this.url(`/v1/threads/discover${qs}`), { headers: this.headers() });
+    if (!r.ok) throw new Error(`discoverThreads ${r.status}`);
+    return (await r.json()) as DiscoveredThread[];
+  }
+
+  /** Self-leave a thread (e.g. leave a channel). */
+  async leaveThread(threadId: string): Promise<{ threadId: string; participantCount: number }> {
+    const r = await fetch(this.url(`/v1/threads/${threadId}/me`), { method: 'DELETE', headers: this.headers() });
+    if (!r.ok) throw new Error(`leaveThread ${r.status}`);
+    return (await r.json()) as { threadId: string; participantCount: number };
+  }
+
   /** My saved messages (personal bookmarks), newest first, with thread context. */
   async listSaved(): Promise<SavedItem[]> {
     const r = await fetch(this.url('/v1/threads/my-annotations?type=save'), { headers: this.headers() });
diff --git a/packages/iios-kernel-client/src/types.ts b/packages/iios-kernel-client/src/types.ts
index 8b32d24..d1b74dd 100644
--- a/packages/iios-kernel-client/src/types.ts
+++ b/packages/iios-kernel-client/src/types.ts
@@ -64,6 +64,15 @@ export interface MessageEvents {
   annotation: (e: AnnotationEvent) => void;
 }
 
+/** A discoverable thread from GET /v1/threads/discover — includes ones you have NOT joined. */
+export interface DiscoveredThread {
+  threadId: string;
+  subject: string | null;
+  metadata: Record<string, unknown> | null;
+  participantCount: number;
+  joined: boolean;
+}
+
 /** A "my threads" entry from GET /v1/threads (server-authoritative). */
 export interface ThreadSummary {
   threadId: string;
diff --git a/packages/iios-messaging-ui/insignia-iios-messaging-ui-0.1.0.tgz b/packages/iios-messaging-ui/insignia-iios-messaging-ui-0.1.0.tgz
new file mode 100644
index 0000000..1958cab
Binary files /dev/null and b/packages/iios-messaging-ui/insignia-iios-messaging-ui-0.1.0.tgz differ
diff --git a/packages/iios-messaging-ui/package.json b/packages/iios-messaging-ui/package.json
new file mode 100644
index 0000000..6a9d110
--- /dev/null
+++ b/packages/iios-messaging-ui/package.json
@@ -0,0 +1,65 @@
+{
+  "name": "@insignia/iios-messaging-ui",
+  "version": "0.1.0",
+  "type": "module",
+  "main": "dist/index.js",
+  "module": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js"
+    },
+    "./adapters/mock": {
+      "types": "./dist/adapters/mock.d.ts",
+      "import": "./dist/adapters/mock.js"
+    },
+    "./adapters/kernel-client": {
+      "types": "./dist/adapters/kernel-client.d.ts",
+      "import": "./dist/adapters/kernel-client.js"
+    },
+    "./adapters/mock-inbox": {
+      "types": "./dist/adapters/mock-inbox.d.ts",
+      "import": "./dist/adapters/mock-inbox.js"
+    },
+    "./conformance": {
+      "types": "./dist/conformance.d.ts",
+      "import": "./dist/conformance.js"
+    },
+    "./styles.css": "./dist/styles.css"
+  },
+  "files": [
+    "dist"
+  ],
+  "scripts": {
+    "build": "tsup",
+    "typecheck": "tsc --noEmit",
+    "test": "vitest run"
+  },
+  "peerDependencies": {
+    "@insignia/iios-kernel-client": "*",
+    "react": ">=18",
+    "react-dom": ">=18"
+  },
+  "peerDependenciesMeta": {
+    "@insignia/iios-kernel-client": {
+      "optional": true
+    }
+  },
+  "devDependencies": {
+    "@insignia/iios-kernel-client": "workspace:*",
+    "@testing-library/dom": "^10.4.0",
+    "@testing-library/react": "^16.1.0",
+    "@types/react": "^19.0.0",
+    "@types/react-dom": "^19.0.0",
+    "jsdom": "^26.0.0",
+    "react": "^19.0.0",
+    "react-dom": "^19.0.0",
+    "tsup": "^8.3.5",
+    "typescript": "^5.7.3",
+    "vitest": "^3.0.5"
+  },
+  "publishConfig": {
+    "registry": "https://git.lynkedup.cloud/api/packages/insignia/npm/"
+  }
+}
diff --git a/packages/iios-messaging-ui/src/adapter.ts b/packages/iios-messaging-ui/src/adapter.ts
new file mode 100644
index 0000000..3ea31f5
--- /dev/null
+++ b/packages/iios-messaging-ui/src/adapter.ts
@@ -0,0 +1,83 @@
+import type {
+  Attachment,
+  ChannelSummary,
+  Conversation,
+  CreateChannelInput,
+  Membership,
+  Message,
+  MessageEvent,
+  Person,
+  SendOpts,
+  Unsubscribe,
+} from './types';
+
+/**
+ * The one seam of this SDK. Hosts implement this; the SDK renders it.
+ *
+ * Lifted from lynkeduppro-crm's MessengerData/ThreadData, which already survived
+ * two implementations (live data-door + mock) — the minimum real evidence that a
+ * seam is genuine rather than imagined.
+ *
+ * Optional methods degrade gracefully: the UI hides the reaction picker when
+ * `react` is absent, and the attach button when `upload` is absent. That is how one
+ * component set serves both a full CRM messenger and a stripped-down widget with no
+ * `mode` prop.
+ */
+export interface MessagingAdapter {
+  listConversations(): Promise<Conversation[]>;
+
+  openThread(p: { participantIds: string[]; membership?: Membership; subject?: string }): Promise<{ threadId: string }>;
+
+  history(threadId: string): Promise<Message[]>;
+
+  send(threadId: string, content: string, opts?: SendOpts): Promise<Message>;
+
+  /** Returns an unsubscribe fn. Implementations MUST be idempotent on repeat unsubscribe. */
+  subscribe(threadId: string, cb: (e: MessageEvent) => void): Unsubscribe;
+
+  sendTyping(threadId: string): void;
+
+  markRead(threadId: string, messageId: string): Promise<void>;
+
+  /**
+   * The current user's actor id, or null if not yet known.
+   *
+   * MUST NOT be inferred from message history. The CRM's bug was exactly that:
+   * scanning for a sent message meant every message read as not-yours until you
+   * had spoken. Adapters derive this from auth/session.
+   */
+  currentActorId(): string | null;
+
+  /** Absent => the UI hides reactions entirely. */
+  react?(threadId: string, messageId: string, emoji: string): Promise<void>;
+
+  /** Absent => the UI hides attachments. Storage/auth/limits are the host's concern. */
+  upload?(file: File): Promise<Attachment>;
+
+  /** Absent => treated as always connected (e.g. a pure-REST adapter). */
+  isConnected?(): boolean;
+
+  /** A thread's members (id + display name), for @mention autocomplete + highlighting.
+   *  Absent => the composer offers no autocomplete (you can still type @text). */
+  listMembers?(threadId: string): Promise<Person[]>;
+
+  /** The people you can start a conversation with (org directory). Drives the "New message"
+   *  people picker. Absent => the UI hides DM/group creation (you can still open channels). */
+  directory?(): Promise<Person[]>;
+
+  // ── Channels (optional capability) ──────────────────────────────
+  // A channel is just a third membership beyond dm/group: a discoverable, joinable room.
+  // Implement all four to enable the channels UI; absent => the UI hides channels entirely.
+
+  /** Discoverable channels in the caller's scope, each flagged `joined`. */
+  browseChannels?(): Promise<ChannelSummary[]>;
+
+  /** Create a channel; the creator joins as admin. Returns the new thread id. */
+  createChannel?(input: CreateChannelInput): Promise<{ threadId: string }>;
+
+  /** Join a (public) channel by id. */
+  joinChannel?(threadId: string): Promise<void>;
+
+  /** Leave a channel by id. */
+  leaveChannel?(threadId: string): Promise<void>;
+}
diff --git a/packages/iios-messaging-ui/src/adapters/kernel-client.test.ts b/packages/iios-messaging-ui/src/adapters/kernel-client.test.ts
new file mode 100644
index 0000000..0785ee5
--- /dev/null
+++ b/packages/iios-messaging-ui/src/adapters/kernel-client.test.ts
@@ -0,0 +1,153 @@
+// Runs the shared adapter conformance suite against KernelClientAdapter — proving it satisfies
+// the same contract as the mock, over the REAL MessageSocket facade. Only the lowest socket.io
+// layer is faked (via kernel-client's own SocketLike seam), so the facade's wire mapping is
+// exercised for real. No live IIOS required.
+
+import { describe, it, expect } from 'vitest';
+import { MessageSocket } from '@insignia/iios-kernel-client';
+import type { Message as KernelMessage, SocketLike } from '@insignia/iios-kernel-client';
+import { runAdapterConformance } from '../conformance';
+import { KernelClientAdapter, type RestPort } from './kernel-client';
+
+const ME = 'me';
+const SEEDED = 'th_seed';
+
+/** An in-memory stand-in for the /message socket.io namespace: stores messages, echoes 'message'. */
+function makeFakeSocket(): SocketLike {
+  const threads = new Map<string, KernelMessage[]>([
+    [
+      SEEDED,
+      [
+        {
+          id: 'seed_1',
+          threadId: SEEDED,
+          senderActorId: 'actor_other',
+          senderId: 'pp_other',
+          senderName: 'Other',
+          content: 'seeded message',
+          createdAt: new Date(0).toISOString(),
+        },
+      ],
+    ],
+  ]);
+  const handlers = new Map<string, Set<(...a: unknown[]) => void>>();
+  let seq = 1;
+
+  const fire = (event: string, payload: unknown): void => handlers.get(event)?.forEach((h) => h(payload));
+
+  return {
+    on(event, handler) {
+      if (!handlers.has(event)) handlers.set(event, new Set());
+      handlers.get(event)!.add(handler);
+      return undefined;
+    },
+    off(event, handler) {
+      handlers.get(event)?.delete(handler);
+      return undefined;
+    },
+    emit() {
+      return undefined; // typing/focus — no echo needed for conformance
+    },
+    async emitWithAck(event, payload) {
+      const p = (payload ?? {}) as {
+        threadId: string;
+        content?: string;
+        parentInteractionId?: string;
+        interactionId?: string;
+        type?: string;
+        value?: string;
+      };
+      if (event === 'open_thread') {
+        if (!threads.has(p.threadId)) threads.set(p.threadId, []);
+        return { threadId: p.threadId, status: 'OPEN', history: [...threads.get(p.threadId)!] };
+      }
+      if (event === 'send_message') {
+        const msg: KernelMessage = {
+          id: `m_${seq++}`,
+          threadId: p.threadId,
+          senderActorId: `actor_${ME}`,
+          senderId: ME,
+          senderName: ME,
+          content: p.content ?? '',
+          createdAt: new Date().toISOString(),
+          ...(p.parentInteractionId ? { parentInteractionId: p.parentInteractionId } : {}),
+        };
+        if (!threads.has(p.threadId)) threads.set(p.threadId, []);
+        threads.get(p.threadId)!.push(msg);
+        fire('message', msg);
+        return msg;
+      }
+      if (event === 'read') return { ok: true };
+      if (event === 'annotate') {
+        fire('annotation', {
+          threadId: p.threadId,
+          interactionId: p.interactionId,
+          type: p.type,
+          value: p.value,
+          op: 'add',
+          users: [ME],
+          userId: ME,
+        });
+        return {};
+      }
+      return {};
+    },
+    connect() {
+      return undefined;
+    },
+    disconnect() {
+      return undefined;
+    },
+    connected: true,
+  };
+}
+
+function makeFakeRest(): RestPort {
+  let seq = 1;
+  return {
+    async listThreads() {
+      return [];
+    },
+    async createThread() {
+      return { threadId: `th_new_${seq++}` };
+    },
+    async addParticipant() {
+      /* governed server-side; a fake always allows */
+    },
+    async discoverThreads() {
+      return [
+        {
+          threadId: 'th_pub',
+          subject: 'general',
+          metadata: { membership: 'channel', visibility: 'public', topic: 'Company-wide' },
+          participantCount: 3,
+          joined: false,
+        },
+      ];
+    },
+    async leaveThread(threadId) {
+      return { threadId, participantCount: 0 };
+    },
+  };
+}
+
+function makeAdapter(): KernelClientAdapter {
+  const socket = new MessageSocket({ serviceUrl: 'http://iios.test', token: 'tok', autoConnect: false }, makeFakeSocket());
+  return new KernelClientAdapter({ currentUserId: ME, socket, rest: makeFakeRest() });
+}
+
+runAdapterConformance({ makeAdapter, seededThreadId: SEEDED, openWith: ['pp_a'] });
+
+describe('KernelClientAdapter channels', () => {
+  it('browse maps discovered public channels; create/join/leave delegate to the transport', async () => {
+    const adapter = makeAdapter();
+    const list = await adapter.browseChannels!();
+    expect(list[0]).toMatchObject({ threadId: 'th_pub', name: 'general', visibility: 'public', joined: false, memberCount: 3, topic: 'Company-wide' });
+
+    const { threadId } = await adapter.createChannel!({ name: 'design', topic: 'UI', visibility: 'public' });
+    expect(typeof threadId).toBe('string');
+
+    await expect(adapter.joinChannel!('th_pub')).resolves.toBeUndefined();
+    await expect(adapter.leaveChannel!('th_pub')).resolves.toBeUndefined();
+  });
+});
diff --git a/packages/iios-messaging-ui/src/adapters/kernel-client.ts b/packages/iios-messaging-ui/src/adapters/kernel-client.ts
new file mode 100644
index 0000000..178aafa
--- /dev/null
+++ b/packages/iios-messaging-ui/src/adapters/kernel-client.ts
@@ -0,0 +1,303 @@
+// Transport adapter: implements MessagingAdapter over @insignia/iios-kernel-client
+// (browser → IIOS directly, token-in). This is the "plug into any app with a token"
+// path — the same transport chat-web and support-sdk use.
+//
+// It lives in adapters/ (the ONLY layer allowed to import a transport) and ships from
+// its own subpath, so core UI never pulls socket code it can't use.
+
+import { MessageSocket, RestClient } from '@insignia/iios-kernel-client';
+import type {
+  AnnotationEvent,
+  DiscoveredThread,
+  Message as KernelMessage,
+  MessageEvents,
+  OpenThreadResult,
+  ReceiptEvent,
+  ThreadSummary,
+  TypingEvent,
+} from '@insignia/iios-kernel-client';
+import type { MessagingAdapter } from '../adapter';
+import type {
+  ChannelSummary,
+  ChannelVisibility,
+  Conversation,
+  CreateChannelInput,
+  Membership,
+  Message,
+  MessageEvent,
+  Reaction,
+  SendOpts,
+  Unsubscribe,
+} from '../types';
+
+/** The slice of MessageSocket the adapter needs — the real facade satisfies it; tests inject a fake. */
+export interface SocketPort {
+  openThread(threadId?: string, opts?: { membership?: string; creatorRole?: string; subject?: string }): Promise<OpenThreadResult>;
+  sendMessage(threadId: string, content: string, opts?: { parentInteractionId?: string; mentions?: string[] }): Promise<KernelMessage>;
+  react(threadId: string, interactionId: string, value: string): Promise<void>;
+  markRead(threadId: string, interactionId: string): Promise<{ ok: boolean }>;
+  typing(threadId: string): void;
+  on<E extends keyof MessageEvents>(event: E, handler: MessageEvents[E]): () => void;
+}
+
+/** The slice of RestClient the adapter needs. */
+export interface RestPort {
+  listThreads(filter?: { metadata?: Record<string, string> }): Promise<ThreadSummary[]>;
+  createThread(opts: { membership?: string; creatorRole?: string; subject?: string; metadata?: Record<string, unknown> }): Promise<{ threadId: string }>;
+  addParticipant(threadId: string, userId: string): Promise<void>;
+  discoverThreads(filter?: { metadata?: Record<string, string> }): Promise<DiscoveredThread[]>;
+  leaveThread(threadId: string): Promise<{ threadId: string; participantCount: number }>;
+}
+
+export interface KernelClientAdapterConfig {
+  /**
+   * The current user's id in IIOS's `senderId` space (email/username), from the host's auth —
+   * NEVER inferred from message history. This is exactly `currentActorId()`, and it's the bug the
+   * conformance suite kills: identity comes from the session, not from a message you happened to send.
+   */
+  currentUserId: string;
+  socket: SocketPort;
+  rest: RestPort;
+  /** Optional opaque metadata filter for the conversation list (e.g. { source: 'crm-messenger' }). */
+  threadFilter?: Record<string, string>;
+}
+
+const REACTION = 'reaction';
+
+export class KernelClientAdapter implements MessagingAdapter {
+  private readonly me: string;
+  private readonly socket: SocketPort;
+  private readonly rest: RestPort;
+  private readonly threadFilter?: Record<string, string>;
+
+  /** Per-thread UI subscribers. The socket fans server events in; these fan them out. */
+  private readonly listeners = new Map<string, Set<(e: MessageEvent) => void>>();
+  /** Reaction users per message (messageId → emoji → userSet), so an annotation delta becomes a full set. */
+  private readonly reactions = new Map<string, Map<string, Set<string>>>();
+  private readonly joined = new Set<string>();
+  private readonly offs: Array<() => void> = [];
+
+  constructor(cfg: KernelClientAdapterConfig) {
+    this.me = cfg.currentUserId;
+    this.socket = cfg.socket;
+    this.rest = cfg.rest;
+    this.threadFilter = cfg.threadFilter;
+
+    this.offs.push(
+      this.socket.on('message', (m: KernelMessage) => {
+        this.ingestReactions(m);
+        this.emit(m.threadId, { kind: 'message', message: this.toMessage(m) });
+      }),
+    );
+    this.offs.push(
+      this.socket.on('typing', (e: TypingEvent) => this.emit(e.threadId, { kind: 'typing', userId: e.userId })),
+    );
+    this.offs.push(
+      // Receipts carry no threadId, so fan to every open thread; the UI filters by messageId.
+      this.socket.on('receipt', (e: ReceiptEvent) => this.broadcast({ kind: 'receipt', messageId: e.interactionId, actorId: e.actorId })),
+    );
+    this.offs.push(
+      this.socket.on('annotation', (e: AnnotationEvent) => {
+        if (e.type !== REACTION) return;
+        this.setReactionUsers(e.interactionId, e.value, e.users);
+        this.emit(e.threadId, { kind: 'reaction', messageId: e.interactionId, reactions: this.reactionsOf(e.interactionId) });
+      }),
+    );
+  }
+
+  currentActorId(): string {
+    return this.me;
+  }
+
+  async listConversations(): Promise<Conversation[]> {
+    const threads = await this.rest.listThreads(this.threadFilter ? { metadata: this.threadFilter } : undefined);
+    return threads.map((t) => this.toConversation(t));
+  }
+
+  async openThread(p: { participantIds: string[]; membership?: Membership; subject?: string }): Promise<{ threadId: string }> {
+    const membership: Membership = p.membership ?? (p.participantIds.length === 1 ? 'dm' : 'group');
+    const { threadId } = await this.rest.createThread({
+      membership,
+      creatorRole: membership === 'group' ? 'ADMIN' : 'MEMBER',
+      ...(p.subject ? { subject: p.subject } : {}),
+    });
+    // Governance (DM cap, roles) is enforced server-side by IIOS/OPA; a rejected add surfaces up there.
+    for (const id of p.participantIds) await this.rest.addParticipant(threadId, id).catch(() => undefined);
+    return { threadId };
+  }
+
+  async history(threadId: string): Promise<Message[]> {
+    const res = await this.socket.openThread(threadId); // joins the thread, so live events start flowing
+    this.joined.add(threadId);
+    return res.history.map((m) => {
+      this.ingestReactions(m);
+      return this.toMessage(m);
+    });
+  }
+
+  async send(threadId: string, content: string, opts?: SendOpts): Promise<Message> {
+    // Attachments are intentionally not forwarded here: kernel-client exposes no media/presign yet,
+    // and the SDK Attachment carries a display `url`, not a storage `contentRef`. Media is a follow-up
+    // (kernel-client media methods + a contentRef on Attachment). Text + reply threading work today.
+    const sendOpts = {
+      ...(opts?.parentInteractionId ? { parentInteractionId: opts.parentInteractionId } : {}),
+      ...(opts?.mentions && opts.mentions.length ? { mentions: opts.mentions } : {}),
+    };
+    const m = await this.socket.sendMessage(threadId, content, Object.keys(sendOpts).length ? sendOpts : undefined);
+    return this.toMessage(m);
+  }
+
+  async react(threadId: string, messageId: string, emoji: string): Promise<void> {
+    await this.socket.react(threadId, messageId, emoji);
+  }
+
+  subscribe(threadId: string, cb: (e: MessageEvent) => void): Unsubscribe {
+    if (!this.listeners.has(threadId)) this.listeners.set(threadId, new Set());
+    this.listeners.get(threadId)!.add(cb);
+    if (!this.joined.has(threadId)) {
+      this.joined.add(threadId);
+      void this.socket.openThread(threadId).catch(() => this.joined.delete(threadId));
+    }
+    return () => {
+      this.listeners.get(threadId)?.delete(cb);
+    };
+  }
+
+  sendTyping(threadId: string): void {
+    this.socket.typing(threadId);
+  }
+
+  async markRead(threadId: string, messageId: string): Promise<void> {
+    await this.socket.markRead(threadId, messageId);
+  }
+
+  // ── Channels ────────────────────────────────────────────────────
+  async browseChannels(): Promise<ChannelSummary[]> {
+    const found = await this.rest.discoverThreads({ metadata: { membership: 'channel', visibility: 'public' } });
+    return found.map((d) => {
+      const bag = (d.metadata as { topic?: string; visibility?: string } | null) ?? {};
+      const visibility: ChannelVisibility = bag.visibility === 'private' ? 'private' : 'public';
+      return {
+        threadId: d.threadId,
+        name: d.subject ?? 'channel',
+        topic: bag.topic ?? null,
+        visibility,
+        memberCount: d.participantCount,
+        joined: d.joined,
+      };
+    });
+  }
+
+  async createChannel(input: CreateChannelInput): Promise<{ threadId: string }> {
+    return this.rest.createThread({
+      membership: 'channel',
+      creatorRole: 'ADMIN',
+      subject: input.name,
+      metadata: { visibility: input.visibility, ...(input.topic ? { topic: input.topic } : {}) },
+    });
+  }
+
+  async joinChannel(threadId: string): Promise<void> {
+    // Self-join is a governed open_thread; OPA allows it for a public channel.
+    await this.socket.openThread(threadId);
+    this.joined.add(threadId);
+  }
+
+  async leaveChannel(threadId: string): Promise<void> {
+    await this.rest.leaveThread(threadId);
+    this.joined.delete(threadId);
+  }
+
+  /** Detach socket handlers. Not part of the contract — call on teardown to avoid leaks. */
+  close(): void {
+    for (const off of this.offs) off();
+    this.offs.length = 0;
+    this.listeners.clear();
+  }
+
+  // ── mapping ────────────────────────────────────────────────────
+  private toMessage(m: KernelMessage): Message {
+    return {
+      id: m.id,
+      // `senderId` (email/username), NOT the actor id — it matches currentActorId() and is the
+      // reliable "is this mine?" field. Never inferred from history.
+      actorId: m.senderId ?? null,
+      text: m.content ?? '',
+      at: m.createdAt,
+      parentInteractionId: m.parentInteractionId ?? null,
+      reactions: this.reactionsOf(m.id),
+    };
+  }
+
+  private toConversation(t: ThreadSummary): Conversation {
+    const others = t.participants.filter((p) => p !== this.me);
+    const membership: Membership | null =
+      t.membership === 'dm' || t.membership === 'group' || t.membership === 'channel' ? t.membership : null;
+    const topic = (t.metadata as { topic?: string } | null)?.topic;
+    return {
+      threadId: t.threadId,
+      title: t.subject?.trim() || others.join(', ') || 'Conversation',
+      subject: t.subject,
+      membership,
+      participants: [...t.participants],
+      unread: t.unread,
+      ...(topic != null ? { topic } : {}),
+      ...(t.lastMessage ? { lastMessage: t.lastMessage } : {}),
+      ...(t.lastAt ? { lastAt: t.lastAt } : {}),
+    };
+  }
+
+  // ── reaction state ─────────────────────────────────────────────
+  private ingestReactions(m: KernelMessage): void {
+    for (const a of m.annotations ?? []) {
+      if (a.type === REACTION) this.setReactionUsers(m.id, a.value, a.users);
+    }
+  }
+
+  private setReactionUsers(messageId: string, emoji: string, users: string[]): void {
+    let byEmoji = this.reactions.get(messageId);
+    if (!byEmoji) {
+      byEmoji = new Map();
+      this.reactions.set(messageId, byEmoji);
+    }
+    if (users.length === 0) byEmoji.delete(emoji);
+    else byEmoji.set(emoji, new Set(users));
+  }
+
+  private reactionsOf(messageId: string): Reaction[] {
+    const byEmoji = this.reactions.get(messageId);
+    if (!byEmoji) return [];
+    const out: Reaction[] = [];
+    for (const [emoji, users] of byEmoji) {
+      if (users.size > 0) out.push({ emoji, count: users.size, mine: users.has(this.me) });
+    }
+    return out;
+  }
+
+  // ── event fan-out ──────────────────────────────────────────────
+  private emit(threadId: string, e: MessageEvent): void {
+    this.listeners.get(threadId)?.forEach((cb) => cb(e));
+  }
+
+  private broadcast(e: MessageEvent): void {
+    for (const set of this.listeners.values()) set.forEach((cb) => cb(e));
+  }
+}
+
+/** Convenience: build an adapter that talks straight to IIOS with a token. */
+export function connectKernelAdapter(opts: {
+  serviceUrl: string;
+  token: string;
+  currentUserId: string;
+  threadFilter?: Record<string, string>;
+  autoConnect?: boolean;
+}): KernelClientAdapter {
+  const rest = new RestClient({ serviceUrl: opts.serviceUrl, token: opts.token });
+  const socket = new MessageSocket({ serviceUrl: opts.serviceUrl, token: opts.token, autoConnect: opts.autoConnect ?? true });
+  return new KernelClientAdapter({
+    currentUserId: opts.currentUserId,
+    socket,
+    rest,
+    ...(opts.threadFilter ? { threadFilter: opts.threadFilter } : {}),
+  });
+}
diff --git a/packages/iios-messaging-ui/src/adapters/mock-inbox.ts b/packages/iios-messaging-ui/src/adapters/mock-inbox.ts
new file mode 100644
index 0000000..c2603e4
--- /dev/null
+++ b/packages/iios-messaging-ui/src/adapters/mock-inbox.ts
@@ -0,0 +1,109 @@
+import type { InboxAdapter } from '../inbox/adapter';
+import type { InboxItem, InboxState, MailAttachment, MailMessage, MailPerson } from '../inbox/types';
+
+const PEOPLE: MailPerson[] = [
+  { id: 'pp_sofia', name: 'Sofia Ramirez', kind: 'staff' },
+  { id: 'pp_dan', name: 'Dan Whitaker', kind: 'staff' },
+  { id: 'cust_acme', name: 'Acme Roofing (Client)', kind: 'customer' },
+];
+
+interface MockMail {
+  subject: string;
+  messages: MailMessage[];
+}
+
+/**
+ * In-memory inbox for demos/tests. State is PER INSTANCE. Seeds a few work items (mention,
+ * needs-reply, alert) plus mail threads that fold into the Open view as MAIL rows.
+ */
+export class MockInboxAdapter implements InboxAdapter {
+  private seq = 100;
+  private readonly items: InboxItem[];
+  private readonly threads = new Map<string, MockMail>();
+  /** threadIds that surface as standalone MAIL rows (in addition to work items). */
+  private readonly mailFold = ['mt_welcome', 'mt_invoice'];
+
+  constructor(private readonly now: () => string = () => new Date().toISOString()) {
+    const at = this.now();
+    this.items = [
+      { id: 'in_1', kind: 'MENTION', state: 'OPEN', title: 'Sofia mentioned you', summary: '@you — can you confirm the Henderson scope?', priority: 'HIGH', threadId: 'mt_mention', createdAt: at },
+      { id: 'in_2', kind: 'NEEDS_REPLY', state: 'OPEN', title: 'Reply needed — Storm response', summary: 'Dan: crew rolling out at 7', priority: 'MEDIUM', threadId: 'mt_storm', createdAt: at },
+      { id: 'in_3', kind: 'SYSTEM_ALERT', state: 'OPEN', title: 'Ticket TK-204 updated', summary: 'Customer replied on the roof-leak case.', priority: 'LOW', createdAt: at },
+    ];
+    this.threads.set('mt_mention', {
+      subject: 'Henderson scope',
+      messages: [{ id: 'm1', actorId: 'pp_sofia', kind: 'EMAIL', at, html: '<p>Can you confirm the <b>Henderson</b> scope by EOD?</p>', text: 'Can you confirm the Henderson scope by EOD?', attachment: null }],
+    });
+    this.threads.set('mt_storm', {
+      subject: 'Storm response — East side',
+      messages: [{ id: 'm2', actorId: 'pp_dan', kind: 'EMAIL', at, html: '<p>Crew is rolling out at 7. Confirm the Henderson job?</p>', text: 'Crew rolling out at 7. Confirm the Henderson job?', attachment: null }],
+    });
+    this.threads.set('mt_welcome', {
+      subject: 'Welcome to the Founders Club',
+      messages: [{ id: 'm3', actorId: 'system', kind: 'EMAIL', at, html: '<p>Thanks for joining the <b>Founders Club</b>. Set up your account to get started.</p>', text: 'Thanks for joining the Founders Club.', attachment: null }],
+    });
+    this.threads.set('mt_invoice', {
+      subject: 'Invoice #1042 — Acme Roofing',
+      messages: [{ id: 'm4', actorId: 'cust_acme', kind: 'EMAIL', at, html: '<p>Attached is invoice <b>#1042</b> for the East-side job.</p>', text: 'Attached is invoice #1042 for the East-side job.', attachment: null }],
+    });
+  }
+
+  async listInbox(state?: InboxState): Promise<InboxItem[]> {
+    const showMail = !state || state === 'OPEN';
+    const work = this.items.filter((i) => (state ? i.state === state : true));
+    const mail: InboxItem[] = showMail
+      ? this.mailFold.map((tid) => {
+          const t = this.threads.get(tid)!;
+          const last = t.messages[t.messages.length - 1];
+          return {
+            id: `mail:${tid}`,
+            kind: 'MAIL',
+            state: 'OPEN' as InboxState,
+            title: t.subject,
+            ...(last?.text ? { summary: last.text } : {}),
+            priority: 'LOW',
+            threadId: tid,
+            createdAt: last?.at ?? this.now(),
+          };
+        })
+      : [];
+    return [...mail, ...work];
+  }
+
+  async transition(id: string, state: InboxState): Promise<void> {
+    const item = this.items.find((i) => i.id === id);
+    if (item) item.state = state;
+  }
+
+  async mailHistory(threadId: string): Promise<MailMessage[]> {
+    return [...(this.threads.get(threadId)?.messages ?? [])];
+  }
+
+  async mailReply(threadId: string, content: string, attachment?: MailAttachment): Promise<void> {
+    const t = this.threads.get(threadId);
+    if (t) t.messages = [...t.messages, { id: `r_${this.seq++}`, actorId: 'me', kind: 'MESSAGE', at: this.now(), html: null, text: content || null, attachment: attachment ?? null }];
+  }
+
+  async uploadAttachment(file: File): Promise<MailAttachment> {
+    return { contentRef: `mock/${this.seq++}`, mimeType: file.type || 'application/octet-stream', sizeBytes: file.size, filename: file.name };
+  }
+
+  async directory(): Promise<MailPerson[]> {
+    return [...PEOPLE];
+  }
+
+  async composeInternal(recipientUserId: string, subject: string, text: string, attachments?: MailAttachment[]): Promise<void> {
+    const threadId = `mt_${this.seq++}`;
+    this.threads.set(threadId, { subject, messages: [{ id: `m_${this.seq++}`, actorId: 'me', kind: 'EMAIL', at: this.now(), html: `<p>${text}</p>`, text, attachment: attachments?.[0] ?? null }] });
+    this.mailFold.unshift(threadId);
+    void recipientUserId;
+  }
+
+  async composeExternal(target: string, subject: string, text: string, attachments?: MailAttachment[]): Promise<void> {
+    // A mock external send has no in-app thread — no-op beyond acknowledging.
+    void target;
+    void subject;
+    void text;
+    void attachments;
+  }
+}
diff --git a/packages/iios-messaging-ui/src/adapters/mock.ts b/packages/iios-messaging-ui/src/adapters/mock.ts
new file mode 100644
index 0000000..e75b370
--- /dev/null
+++ b/packages/iios-messaging-ui/src/adapters/mock.ts
@@ -0,0 +1,252 @@
+import type { MessagingAdapter } from '../adapter';
+import type {
+  Attachment,
+  ChannelSummary,
+  ChannelVisibility,
+  Conversation,
+  CreateChannelInput,
+  Membership,
+  Message,
+  MessageEvent,
+  Person,
+  SendOpts,
+  Unsubscribe,
+} from '../types';
+
+const ME = 'me';
+
+export const MOCK_PEOPLE: Person[] = [
+  { id: 'pp_sofia', name: 'Sofia Ramirez', kind: 'staff' },
+  { id: 'pp_dan', name: 'Dan Whitaker', kind: 'staff' },
+  { id: 'pp_priya', name: 'Priya Nair', kind: 'staff' },
+  { id: 'cust_acme', name: 'Acme Roofing (Client)', kind: 'customer' },
+  { id: 'cust_globex', name: 'Globex Homes (Client)', kind: 'customer' },
+];
+
+interface MockThread {
+  threadId: string;
+  membership: Membership;
+  subject: string | null;
+  participants: string[];
+  messages: Message[];
+  topic?: string | null;
+  visibility?: ChannelVisibility;
+}
+
+const nameById = new Map(MOCK_PEOPLE.map((p) => [p.id, p.name]));
+
+/**
+ * In-memory adapter for demos and tests. State is PER INSTANCE — the CRM's version
+ * used a module-level Map, which leaks between tests. Each `new MockAdapter()` is
+ * fully isolated.
+ */
+export class MockAdapter implements MessagingAdapter {
+  private seq = 100;
+  private threads = new Map<string, MockThread>();
+  private listeners = new Map<string, Set<(e: MessageEvent) => void>>();
+
+  constructor(private readonly now: () => string = () => new Date().toISOString()) {
+    const seededAt = this.now();
+    this.threads.set('th_mock_1', {
+      threadId: 'th_mock_1',
+      membership: 'dm',
+      subject: null,
+      participants: [ME, 'pp_sofia'],
+      messages: [
+        {
+          id: 'm1',
+          actorId: 'pp_sofia',
+          text: 'Can you review the Henderson estimate?',
+          at: seededAt,
+          reactions: [],
+        },
+      ],
+    });
+    this.threads.set('th_mock_2', {
+      threadId: 'th_mock_2',
+      membership: 'group',
+      subject: 'Storm response — East side',
+      participants: [ME, 'pp_dan', 'pp_priya'],
+      messages: [
+        { id: 'm2', actorId: 'pp_dan', text: 'Crew is rolling out at 7.', at: seededAt, reactions: [] },
+      ],
+    });
+    // Channels: a joined public one, a joinable public one (I'm NOT in it → shows in browse only),
+    // and a private one I'm a member of.
+    this.threads.set('th_ch_general', {
+      threadId: 'th_ch_general', membership: 'channel', subject: 'general', topic: 'Company-wide chatter',
+      visibility: 'public', participants: [ME, 'pp_dan', 'pp_priya', 'pp_sofia'],
+      messages: [{ id: 'c1', actorId: 'pp_priya', text: 'Welcome to #general 👋', at: seededAt, reactions: [] }],
+    });
+    this.threads.set('th_ch_random', {
+      threadId: 'th_ch_random', membership: 'channel', subject: 'random', topic: 'Non-work banter',
+      visibility: 'public', participants: ['pp_dan', 'pp_sofia'], messages: [],
+    });
+    this.threads.set('th_ch_deals', {
+      threadId: 'th_ch_deals', membership: 'channel', subject: 'deals', topic: 'Big pipeline moves',
+      visibility: 'private', participants: [ME, 'pp_sofia'], messages: [],
+    });
+  }
+
+  currentActorId(): string {
+    return ME;
+  }
+
+  async listConversations(): Promise<Conversation[]> {
+    // Only threads I'm a member of — an un-joined public channel appears in browse, not here.
+    return [...this.threads.values()]
+      .filter((t) => t.participants.includes(ME))
+      .map((t) => {
+        const last = t.messages[t.messages.length - 1];
+        const others = t.participants.filter((p) => p !== ME);
+        return {
+          threadId: t.threadId,
+          title: t.subject || others.map((id) => nameById.get(id) ?? id).join(', ') || 'Conversation',
+          subject: t.subject,
+          membership: t.membership,
+          participants: [...t.participants],
+          unread: 0,
+          ...(t.topic != null ? { topic: t.topic } : {}),
+          ...(last ? { lastMessage: last.text, lastAt: last.at } : {}),
+        };
+      });
+  }
+
+  async browseChannels(): Promise<ChannelSummary[]> {
+    // Public channels are discoverable; private ones only if I'm already a member.
+    return [...this.threads.values()]
+      .filter((t) => t.membership === 'channel' && (t.visibility === 'public' || t.participants.includes(ME)))
+      .map((t) => ({
+        threadId: t.threadId,
+        name: t.subject ?? 'channel',
+        topic: t.topic ?? null,
+        visibility: t.visibility ?? 'public',
+        memberCount: t.participants.length,
+        joined: t.participants.includes(ME),
+      }));
+  }
+
+  async createChannel(input: CreateChannelInput): Promise<{ threadId: string }> {
+    const threadId = `th_ch_${this.seq++}`;
+    this.threads.set(threadId, {
+      threadId,
+      membership: 'channel',
+      subject: input.name,
+      topic: input.topic ?? null,
+      visibility: input.visibility,
+      participants: [ME],
+      messages: [],
+    });
+    return { threadId };
+  }
+
+  async joinChannel(threadId: string): Promise<void> {
+    const t = this.threads.get(threadId);
+    if (t && !t.participants.includes(ME)) t.participants = [...t.participants, ME];
+  }
+
+  async leaveChannel(threadId: string): Promise<void> {
+    const t = this.threads.get(threadId);
+    if (t) t.participants = t.participants.filter((p) => p !== ME);
+  }
+
+  async listMembers(threadId: string): Promise<Person[]> {
+    const t = this.threads.get(threadId);
+    if (!t) return [];
+    return t.participants.map((id) => {
+      if (id === ME) return { id: ME, name: 'You', kind: 'staff' };
+      return MOCK_PEOPLE.find((p) => p.id === id) ?? { id, name: id, kind: 'staff' };
+    });
+  }
+
+  async directory(): Promise<Person[]> {
+    return MOCK_PEOPLE.map((p) => ({ ...p }));
+  }
+
+  async openThread(p: { participantIds: string[]; membership?: Membership; subject?: string }): Promise<{ threadId: string }> {
+    // A DM to someone you already have reuses the existing 1:1 thread (dedupe, like the live door).
+    if ((p.membership ?? (p.participantIds.length === 1 ? 'dm' : 'group')) === 'dm' && p.participantIds.length === 1) {
+      const target = p.participantIds[0];
+      for (const [id, t] of this.threads) {
+        if (t.membership === 'dm' && t.participants.length === 2 && t.participants.includes(ME) && t.participants.includes(target)) {
+          return { threadId: id };
+        }
+      }
+    }
+    const membership = p.membership ?? (p.participantIds.length === 1 ? 'dm' : 'group');
+    const threadId = `th_mock_${this.seq++}`;
+    this.threads.set(threadId, {
+      threadId,
+      membership,
+      subject: p.subject ?? null,
+      participants: [ME, ...p.participantIds],
+      messages: [],
+    });
+    return { threadId };
+  }
+
+  async history(threadId: string): Promise<Message[]> {
+    return [...(this.threads.get(threadId)?.messages ?? [])];
+  }
+
+  async send(threadId: string, content: string, opts?: SendOpts): Promise<Message> {
+    const t = this.threads.get(threadId);
+    if (!t) throw new Error(`Unknown thread: ${threadId}`);
+    const message: Message = {
+      id: `m_${this.seq++}`,
+      actorId: ME,
+      text: content,
+      at: this.now(),
+      reactions: [],
+      ...(opts?.parentInteractionId ? { parentInteractionId: opts.parentInteractionId } : {}),
+      ...(opts?.attachment ? { attachment: opts.attachment } : {}),
+    };
+    t.messages = [...t.messages, message];
+    this.emit(threadId, { kind: 'message', message });
+    return message;
+  }
+
+  async react(threadId: string, messageId: string, emoji: string): Promise<void> {
+    const t = this.threads.get(threadId);
+    if (!t) return;
+    let next: Message | undefined;
+    t.messages = t.messages.map((m) => {
+      if (m.id !== messageId) return m;
+      const existing = (m.reactions ?? []).find((r) => r.emoji === emoji);
+      const reactions = existing
+        ? (m.reactions ?? []).filter((r) => r.emoji !== emoji)
+        : [...(m.reactions ?? []), { emoji, count: 1, mine: true }];
+      next = { ...m, reactions };
+      return next;
+    });
+    if (next) this.emit(threadId, { kind: 'reaction', messageId, reactions: next.reactions ?? [] });
+  }
+
+  async upload(file: File): Promise<Attachment> {
+    return { url: `mock://uploads/${file.name}`, mime: file.type, name: file.name };
+  }
+
+  subscribe(threadId: string, cb: (e: MessageEvent) => void): Unsubscribe {
+    if (!this.listeners.has(threadId)) this.listeners.set(threadId, new Set());
+    this.listeners.get(threadId)!.add(cb);
+    return () => {
+      this.listeners.get(threadId)?.delete(cb);
+    };
+  }
+
+  sendTyping(): void {
+    // No-op: nobody is typing back in a mock.
+  }
+
+  async markRead(): Promise<void> {
+    // No-op: the mock has no second party to report a read.
+  }
+
+  isConnected(): boolean {
+    return true;
+  }
+
+  private emit(threadId: string, e: MessageEvent): void {
+    this.listeners.get(threadId)?.forEach((cb) => cb(e));
+  }
+}
diff --git a/packages/iios-messaging-ui/src/boundary.test.ts b/packages/iios-messaging-ui/src/boundary.test.ts
new file mode 100644
index 0000000..4efa2de
--- /dev/null
+++ b/packages/iios-messaging-ui/src/boundary.test.ts
@@ -0,0 +1,41 @@
+// @vitest-environment node
+import { describe, it, expect } from 'vitest';
+import { readdirSync, readFileSync, statSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { join } from 'node:path';
+
+// This package is ESM ("type": "module") — __dirname does not exist here.
+const SRC = fileURLToPath(new URL('.', import.meta.url));
+const ADAPTERS = join(SRC, 'adapters');
+
+function tsFilesIn(dir: string): string[] {
+  const out: string[] = [];
+  for (const entry of readdirSync(dir)) {
+    const full = join(dir, entry);
+    if (statSync(full).isDirectory()) out.push(...tsFilesIn(full));
+    else if (/\.tsx?$/.test(full)) out.push(full);
+  }
+  return out;
+}
+
+// The whole premise of this package: core renders, adapters transport. If core ever
+// imports a transport, an app on a different backend pays for socket code it cannot
+// use — which is exactly how iios-message-web welded itself to MessageSocket.
+describe('transport boundary', () => {
+  const coreFiles = tsFilesIn(SRC).filter((f) => !f.startsWith(ADAPTERS) && !/\.test\.tsx?$/.test(f));
+
+  it('has core files to check', () => {
+    expect(coreFiles.length).toBeGreaterThan(0);
+  });
+
+  it('core never imports a transport package', () => {
+    const offenders: string[] = [];
+    for (const file of coreFiles) {
+      const content = readFileSync(file, 'utf8');
+      if (/@insignia\/iios-kernel-client|socket\.io|@abe-kap\/appshell-sdk/.test(content)) {
+        offenders.push(file.replace(SRC, 'src'));
+      }
+    }
+    expect(offenders).toEqual([]);
+  });
+});
diff --git a/packages/iios-messaging-ui/src/components/channel-browser.tsx b/packages/iios-messaging-ui/src/components/channel-browser.tsx
new file mode 100644
index 0000000..876eeba
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/channel-browser.tsx
@@ -0,0 +1,93 @@
+import { useState, type FormEvent } from 'react';
+import { useChannels } from '../hooks/use-channels';
+import type { ChannelVisibility } from '../types';
+
+/** Browse + join discoverable channels, and create a new one. Shown in the main pane. */
+export function ChannelBrowser({ onJoined }: { onJoined?: (threadId: string) => void }) {
+  const { browsable, loading, error, join, create } = useChannels();
+  const [name, setName] = useState('');
+  const [topic, setTopic] = useState('');
+  const [visibility, setVisibility] = useState<ChannelVisibility>('public');
+  const [busy, setBusy] = useState(false);
+
+  async function submitCreate(e: FormEvent): Promise<void> {
+    e.preventDefault();
+    const n = name.trim();
+    if (!n || busy) return;
+    setBusy(true);
+    try {
+      const threadId = await create({ name: n, ...(topic.trim() ? { topic: topic.trim() } : {}), visibility });
+      setName('');
+      setTopic('');
+      onJoined?.(threadId);
+    } catch {
+      // surfaced via the hook's error
+    } finally {
+      setBusy(false);
+    }
+  }
+
+  async function doJoin(threadId: string): Promise<void> {
+    await join(threadId);
+    onJoined?.(threadId);
+  }
+
+  return (
+    <div className="miu-browser">
+      <div className="miu-browser-head">Channels</div>
+
+      <form className="miu-channel-create" onSubmit={submitCreate}>
+        <input
+          className="miu-input"
+          value={name}
+          onChange={(e) => setName(e.target.value)}
+          placeholder="New channel name"
+          aria-label="Channel name"
+        />
+        <input
+          className="miu-input"
+          value={topic}
+          onChange={(e) => setTopic(e.target.value)}
+          placeholder="Topic (optional)"
+          aria-label="Channel topic"
+        />
+        <div className="miu-channel-vis">
+          <label>
+            <input type="radio" name="miu-vis" checked={visibility === 'public'} onChange={() => setVisibility('public')} /> Public
+          </label>
+          <label>
+            <input type="radio" name="miu-vis" checked={visibility === 'private'} onChange={() => setVisibility('private')} /> Private
+          </label>
+        </div>
+        <button type="submit" className="miu-send" disabled={!name.trim() || busy}>
+          Create
+        </button>
+      </form>
+
+      <div className="miu-browser-list">
+        {loading && browsable.length === 0 ? <div className="miu-empty">Loading…</div> : null}
+        {error ? <div className="miu-empty miu-error">{error}</div> : null}
+        {!loading && browsable.length === 0 ? <div className="miu-empty">No channels yet — create one above.</div> : null}
+        {browsable.map((c) => (
+          <div key={c.threadId} className="miu-browser-row">
+            <span className="miu-channel-glyph" aria-hidden="true">{c.visibility === 'private' ? '🔒' : '#'}</span>
+            <span className="miu-browser-main">
+              <span className="miu-browser-name">{c.name}</span>
+              {c.topic ? <span className="miu-browser-topic">{c.topic}</span> : null}
+              <span className="miu-browser-meta">
+                {c.memberCount} member{c.memberCount === 1 ? '' : 's'}
+              </span>
+            </span>
+            {c.joined ? (
+              <span className="miu-browser-joined">Joined</span>
+            ) : (
+              <button type="button" className="miu-join" onClick={() => void doJoin(c.threadId)}>
+                Join
+              </button>
+            )}
+          </div>
+        ))}
+      </div>
+    </div>
+  );
+}
diff --git a/packages/iios-messaging-ui/src/components/channels.test.tsx b/packages/iios-messaging-ui/src/components/channels.test.tsx
new file mode 100644
index 0000000..05cfe61
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/channels.test.tsx
@@ -0,0 +1,54 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { MessagingProvider } from '../provider';
+import { Messenger } from './messenger';
+import { MockAdapter } from '../adapters/mock';
+
+function mount() {
+  return render(
+    <MessagingProvider adapter={new MockAdapter()}>
+      <Messenger />
+    </MessagingProvider>,
+  );
+}
+
+describe('channels (mock adapter)', () => {
+  it('browse returns public channels + private ones I am in, with a joined flag', async () => {
+    const a = new MockAdapter();
+    const list = await a.browseChannels();
+    const byId = new Map(list.map((c) => [c.threadId, c]));
+    expect(byId.get('th_ch_general')?.joined).toBe(true); // public, I'm in
+    expect(byId.get('th_ch_random')?.joined).toBe(false); // public, I'm NOT in
+    expect(byId.get('th_ch_deals')?.joined).toBe(true); // private, I'm in
+    // A private channel I'm not in must never surface in browse — none seeded, so all private here are mine.
+    expect(list.every((c) => c.visibility === 'public' || c.joined)).toBe(true);
+  });
+
+  it('join adds me and the channel then appears in my conversation list', async () => {
+    const a = new MockAdapter();
+    expect((await a.listConversations()).some((c) => c.threadId === 'th_ch_random')).toBe(false);
+    await a.joinChannel('th_ch_random');
+    expect((await a.listConversations()).some((c) => c.threadId === 'th_ch_random')).toBe(true);
+    expect((await a.browseChannels()).find((c) => c.threadId === 'th_ch_random')?.joined).toBe(true);
+  });
+
+  it('create makes a channel I am a member of', async () => {
+    const a = new MockAdapter();
+    const { threadId } = await a.createChannel({ name: 'design', topic: 'UI stuff', visibility: 'public' });
+    const conv = (await a.listConversations()).find((c) => c.threadId === threadId);
+    expect(conv?.membership).toBe('channel');
+    expect(conv?.topic).toBe('UI stuff');
+  });
+
+  it('UI: browse, then join a channel — it moves into the Channels section', async () => {
+    mount();
+    // Open the browser via the Channels section "+".
+    fireEvent.click(await screen.findByTitle('Browse channels'));
+    // #random is browse-only (not joined) → has a Join button.
+    expect(await screen.findByText('random')).toBeTruthy();
+    const joinButtons = screen.getAllByText('Join');
+    fireEvent.click(joinButtons[0]!);
+    // After joining, we jump to the thread and the browser closes → composer is shown.
+    await waitFor(() => expect(screen.getByLabelText('Message')).toBeTruthy());
+  });
+});
diff --git a/packages/iios-messaging-ui/src/components/composer.tsx b/packages/iios-messaging-ui/src/components/composer.tsx
new file mode 100644
index 0000000..56c50ec
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/composer.tsx
@@ -0,0 +1,147 @@
+import { useMemo, useRef, useState, type ChangeEvent, type FormEvent, type KeyboardEvent } from 'react';
+import {
+  SPECIAL_MENTIONS,
+  insertMention,
+  resolveMentions,
+  trailingMentionQuery,
+} from '../mentions';
+import type { Attachment, Person, SendOpts } from '../types';
+
+interface Suggestion {
+  key: string;
+  label: string;
+  insert: string;
+}
+
+/**
+ * The message input: draft, @mention autocomplete, and attachment staging. Shared by the main
+ * Thread and the ThreadPane (which passes a parentInteractionId so a reply lands in the thread).
+ */
+export function Composer({
+  members,
+  canUpload,
+  upload,
+  onSend,
+  onTyping,
+  parentInteractionId,
+  placeholder = 'Type a message… @ to mention',
+}: {
+  members: Person[];
+  canUpload: boolean;
+  upload: (file: File) => Promise<Attachment>;
+  onSend: (text: string, opts?: SendOpts) => Promise<void>;
+  onTyping?: () => void;
+  parentInteractionId?: string;
+  placeholder?: string;
+}) {
+  const [draft, setDraft] = useState('');
+  const [sending, setSending] = useState(false);
+  const [staged, setStaged] = useState<Attachment | null>(null);
+  const [uploading, setUploading] = useState(false);
+  const fileRef = useRef<HTMLInputElement>(null);
+
+  const query = trailingMentionQuery(draft);
+  const suggestions = useMemo<Suggestion[]>(() => {
+    if (query === null) return [];
+    const q = query.toLowerCase();
+    const specials = SPECIAL_MENTIONS.filter((s) => s.startsWith(q)).map((s) => ({ key: `@${s}`, label: `@${s}`, insert: s }));
+    const people = members.filter((m) => m.name.toLowerCase().includes(q)).map((m) => ({ key: m.id, label: m.name, insert: m.name }));
+    return [...specials, ...people].slice(0, 6);
+  }, [query, members]);
+  const showSuggest = query !== null && suggestions.length > 0;
+
+  function pick(insert: string): void {
+    setDraft((d) => insertMention(d, insert));
+  }
+
+  async function onPickFile(e: ChangeEvent<HTMLInputElement>): Promise<void> {
+    const file = e.target.files?.[0];
+    e.target.value = '';
+    if (!file) return;
+    setUploading(true);
+    try {
+      setStaged(await upload(file));
+    } catch {
+      /* host surfaces upload errors */
+    } finally {
+      setUploading(false);
+    }
+  }
+
+  async function submit(e?: FormEvent): Promise<void> {
+    e?.preventDefault();
+    const text = draft.trim();
+    if ((!text && !staged) || sending) return;
+    const mentions = resolveMentions(text, members);
+    const att = staged;
+    setDraft('');
+    setStaged(null);
+    setSending(true);
+    try {
+      await onSend(text, {
+        ...(mentions.length ? { mentions } : {}),
+        ...(att ? { attachment: att } : {}),
+        ...(parentInteractionId ? { parentInteractionId } : {}),
+      });
+    } catch {
+      setStaged(att);
+    } finally {
+      setSending(false);
+    }
+  }
+
+  function onKeyDown(e: KeyboardEvent<HTMLInputElement>): void {
+    if (showSuggest && e.key === 'Enter') {
+      e.preventDefault();
+      pick(suggestions[0]!.insert);
+    }
+  }
+
+  return (
+    <form className="miu-composer" onSubmit={submit}>
+      {showSuggest ? (
+        <ul className="miu-suggest" role="listbox" aria-label="Mention suggestions">
+          {suggestions.map((s) => (
+            <li key={s.key}>
+              <button type="button" role="option" aria-selected="false" className="miu-suggest-item" onClick={() => pick(s.insert)}>
+                {s.label}
+              </button>
+            </li>
+          ))}
+        </ul>
+      ) : null}
+      {staged ? (
+        <div className="miu-staged">
+          📎 {staged.name}
+          <button type="button" className="miu-staged-x" onClick={() => setStaged(null)} aria-label="Remove attachment">
+            ✕
+          </button>
+        </div>
+      ) : null}
+      <div className="miu-composer-row">
+        {canUpload ? (
+          <>
+            <input ref={fileRef} type="file" className="miu-file-input" onChange={onPickFile} aria-label="Attach a file" />
+            <button type="button" className="miu-attach-btn" title="Attach a file" disabled={uploading} onClick={() => fileRef.current?.click()}>
+              {uploading ? '…' : '📎'}
+            </button>
+          </>
+        ) : null}
+        <input
+          className="miu-input"
+          value={draft}
+          placeholder={placeholder}
+          aria-label="Message"
+          onChange={(e) => {
+            setDraft(e.target.value);
+            onTyping?.();
+          }}
+          onKeyDown={onKeyDown}
+        />
+        <button type="submit" className="miu-send" disabled={(!draft.trim() && !staged) || sending}>
+          Send
+        </button>
+      </div>
+    </form>
+  );
+}
diff --git a/packages/iios-messaging-ui/src/components/conversation-list.tsx b/packages/iios-messaging-ui/src/components/conversation-list.tsx
new file mode 100644
index 0000000..828a910
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/conversation-list.tsx
@@ -0,0 +1,52 @@
+import type { Conversation } from '../types';
+
+/** Initials for the avatar chip — first letters of the first two words. */
+function initials(title: string): string {
+  const parts = title.trim().split(/\s+/).filter(Boolean);
+  const chars = (parts[0]?.[0] ?? '') + (parts[1]?.[0] ?? '');
+  return (chars || '?').toUpperCase();
+}
+
+/**
+ * Presentational conversation list. Owns no data fetching — the parent passes the
+ * conversations (from useConversations) so a host can also drive it from its own store.
+ */
+export function ConversationList({
+  conversations,
+  selectedId,
+  onSelect,
+}: {
+  conversations: Conversation[];
+  selectedId?: string | null;
+  onSelect: (threadId: string) => void;
+}) {
+  if (conversations.length === 0) {
+    return <div className="miu-empty">No conversations yet.</div>;
+  }
+  return (
+    <ul className="miu-convlist" role="list">
+      {conversations.map((c) => (
+        <li key={c.threadId}>
+          <button
+            type="button"
+            className={`miu-convrow${c.threadId === selectedId ? ' is-active' : ''}`}
+            onClick={() => onSelect(c.threadId)}
+          >
+            <span className="miu-avatar" aria-hidden="true">
+              {c.membership === 'channel' ? '#' : initials(c.title)}
+            </span>
+            <span className="miu-convrow-main">
+              <span className="miu-convrow-title">{c.title}</span>
+              {c.lastMessage ? <span className="miu-convrow-preview">{c.lastMessage}</span> : null}
+            </span>
+            {c.unread > 0 ? (
+              <span className="miu-badge" aria-label={`${c.unread} unread`}>
+                {c.unread}
+              </span>
+            ) : null}
+          </button>
+        </li>
+      ))}
+    </ul>
+  );
+}
diff --git a/packages/iios-messaging-ui/src/components/message-item.tsx b/packages/iios-messaging-ui/src/components/message-item.tsx
new file mode 100644
index 0000000..34c0f9f
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/message-item.tsx
@@ -0,0 +1,107 @@
+import { useState } from 'react';
+import { highlightMentions } from '../mentions';
+import type { Attachment } from '../types';
+import type { UiMessage } from '../hooks/use-messages';
+
+const REACTION_EMOJIS = ['👍', '❤️', '😂', '🎉', '👀'];
+
+const isImage = (mime: string): boolean => mime.startsWith('image/');
+
+function AttachmentView({ att }: { att: Attachment }) {
+  if (isImage(att.mime)) {
+    return (
+      <a href={att.url} target="_blank" rel="noreferrer" className="miu-att-img-link">
+        <img src={att.url} alt={att.name} className="miu-att-img" />
+      </a>
+    );
+  }
+  return (
+    <a href={att.url} target="_blank" rel="noreferrer" className="miu-att-file">
+      📎 {att.name}
+    </a>
+  );
+}
+
+/** One rendered message: bubble (with @mention highlighting), attachment, reactions, seen tick,
+ *  and — in the main thread only — a thread/reply affordance. */
+export function MessageItem({
+  message,
+  memberNames,
+  canReact,
+  onReact,
+  seen,
+  replyCount,
+  onOpenThread,
+}: {
+  message: UiMessage;
+  memberNames: string[];
+  canReact: boolean;
+  onReact: (messageId: string, emoji: string) => void;
+  seen: boolean;
+  /** Present only in the main thread (not inside the pane). undefined => no thread affordance. */
+  replyCount?: number;
+  onOpenThread?: (messageId: string) => void;
+}) {
+  const [pickerOpen, setPickerOpen] = useState(false);
+  const m = message;
+
+  return (
+    <div className={`miu-msg${message.mine ? ' is-mine' : ''}${message.pending ? ' is-pending' : ''}`}>
+      <div className="miu-bubble-row">
+        <div className="miu-bubble">
+          {m.text ? highlightMentions(m.text, memberNames) : null}
+          {m.attachment ? <AttachmentView att={m.attachment} /> : null}
+        </div>
+        <div className="miu-msg-actions">
+          {canReact ? (
+            <div className="miu-react-wrap">
+              <button type="button" className="miu-react-btn" title="React" onClick={() => setPickerOpen((p) => !p)}>
+                🙂
+              </button>
+              {pickerOpen ? (
+                <div className="miu-react-picker">
+                  {REACTION_EMOJIS.map((e) => (
+                    <button
+                      key={e}
+                      type="button"
+                      className="miu-react-emoji"
+                      onClick={() => {
+                        onReact(m.id, e);
+                        setPickerOpen(false);
+                      }}
+                    >
+                      {e}
+                    </button>
+                  ))}
+                </div>
+              ) : null}
+            </div>
+          ) : null}
+          {onOpenThread ? (
+            <button type="button" className="miu-react-btn" title="Reply in thread" onClick={() => onOpenThread(m.id)}>
+              💬
+            </button>
+          ) : null}
+        </div>
+      </div>
+
+      {m.reactions && m.reactions.length > 0 ? (
+        <div className="miu-reactions">
+          {m.reactions.map((r) => (
+            <button key={r.emoji} type="button" className={`miu-reaction${r.mine ? ' is-mine' : ''}`} onClick={() => canReact && onReact(m.id, r.emoji)}>
+              {r.emoji} {r.count}
+            </button>
+          ))}
+        </div>
+      ) : null}
+
+      {replyCount !== undefined && replyCount > 0 && onOpenThread ? (
+        <button type="button" className="miu-thread-link" onClick={() => onOpenThread(m.id)}>
+          💬 {replyCount} {replyCount === 1 ? 'reply' : 'replies'}
+        </button>
+      ) : null}
+
+      {message.mine && seen ? <span className="miu-seen">Seen</span> : null}
+    </div>
+  );
+}
diff --git a/packages/iios-messaging-ui/src/components/messenger.test.tsx b/packages/iios-messaging-ui/src/components/messenger.test.tsx
new file mode 100644
index 0000000..d58e0b1
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/messenger.test.tsx
@@ -0,0 +1,42 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { MessagingProvider } from '../provider';
+import { Messenger } from './messenger';
+import { MockAdapter } from '../adapters/mock';
+
+function mount() {
+  return render(
+    <MessagingProvider adapter={new MockAdapter()}>
+      <Messenger />
+    </MessagingProvider>,
+  );
+}
+
+describe('<Messenger /> (rendered UI over an adapter)', () => {
+  it('renders the conversation list and auto-selects the first thread', async () => {
+    mount();
+    // Seeded group conversation title from the mock.
+    expect(await screen.findByText('Storm response — East side')).toBeTruthy();
+    // Auto-selected thread shows its seeded message.
+    expect(await screen.findByText('Crew is rolling out at 7.')).toBeTruthy();
+  });
+
+  it('sends a message through the adapter and shows it in the thread', async () => {
+    mount();
+    // Wait for the auto-selected thread's composer (avoids a race with the auto-select effect).
+    const input = (await screen.findByLabelText('Message')) as HTMLInputElement;
+    fireEvent.change(input, { target: { value: 'on our way' } });
+    fireEvent.click(screen.getByText('Send'));
+
+    await waitFor(() => expect(screen.getByText('on our way')).toBeTruthy());
+    // Composer cleared after send.
+    expect(input.value).toBe('');
+  });
+
+  it('switches threads when another conversation is clicked', async () => {
+    mount();
+    // Click the DM (its title is the other participant's name from the mock directory).
+    fireEvent.click(await screen.findByText('Sofia Ramirez'));
+    expect(await screen.findByText('Can you review the Henderson estimate?')).toBeTruthy();
+  });
+});
diff --git a/packages/iios-messaging-ui/src/components/messenger.tsx b/packages/iios-messaging-ui/src/components/messenger.tsx
new file mode 100644
index 0000000..2b7e54e
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/messenger.tsx
@@ -0,0 +1,116 @@
+import { useEffect, useMemo, useState } from 'react';
+import { useConversations } from '../hooks/use-conversations';
+import { useAdapter } from '../provider';
+import { ConversationList } from './conversation-list';
+import { ChannelBrowser } from './channel-browser';
+import { NewConversation } from './new-conversation';
+import { Thread } from './thread';
+import { ThreadPane } from './thread-pane';
+
+/**
+ * The drop-in messenger: sectioned conversation list (Channels / Direct messages) + open thread,
+ * with a channel browser when the adapter supports channels. Owns only selection + browse state;
+ * all data flows through the injected adapter via the hooks.
+ */
+export function Messenger() {
+  const { conversations, loading, error, refetch } = useConversations();
+  const adapter = useAdapter();
+  const channelsSupported = typeof adapter.browseChannels === 'function';
+  const directorySupported = typeof adapter.directory === 'function';
+
+  const [selected, setSelected] = useState<string | null>(null);
+  const [browsing, setBrowsing] = useState(false);
+  const [composing, setComposing] = useState(false); // "New message" people picker open
+  const [activeRoot, setActiveRoot] = useState<string | null>(null); // open thread pane's root message
+
+  useEffect(() => {
+    if (browsing || composing) return;
+    if (selected && conversations.some((c) => c.threadId === selected)) return;
+    setSelected(conversations[0]?.threadId ?? null);
+  }, [conversations, selected, browsing, composing]);
+
+  // Switching conversations (or into browse/compose) closes any open thread pane.
+  useEffect(() => setActiveRoot(null), [selected, browsing, composing]);
+
+  const channels = useMemo(() => conversations.filter((c) => c.membership === 'channel'), [conversations]);
+  const dms = useMemo(() => conversations.filter((c) => c.membership !== 'channel'), [conversations]);
+
+  function pick(threadId: string): void {
+    setBrowsing(false);
+    setComposing(false);
+    setSelected(threadId);
+  }
+
+  function openBrowse(): void {
+    setComposing(false);
+    setBrowsing(true);
+  }
+
+  function openCompose(): void {
+    setBrowsing(false);
+    setComposing(true);
+  }
+
+  return (
+    <div className="miu-messenger">
+      <aside className="miu-sidebar">
+        {loading && conversations.length === 0 ? <div className="miu-empty">Loading…</div> : null}
+        {error ? <div className="miu-empty miu-error">{error}</div> : null}
+
+        {channelsSupported ? (
+          <div className="miu-section">
+            <div className="miu-section-head">
+              <span>Channels</span>
+              <button type="button" className="miu-section-add" title="Browse channels" onClick={openBrowse}>
+                ＋
+              </button>
+            </div>
+            {channels.length > 0 ? (
+              <ConversationList conversations={channels} selectedId={browsing || composing ? null : selected} onSelect={pick} />
+            ) : (
+              <div className="miu-empty miu-empty-sm">Browse to join a channel.</div>
+            )}
+          </div>
+        ) : null}
+
+        <div className="miu-section">
+          {channelsSupported || directorySupported ? (
+            <div className="miu-section-head">
+              <span>Direct messages</span>
+              {directorySupported ? (
+                <button type="button" className="miu-section-add" title="New message" onClick={openCompose}>
+                  ＋
+                </button>
+              ) : null}
+            </div>
+          ) : null}
+          <ConversationList conversations={dms} selectedId={browsing || composing ? null : selected} onSelect={pick} />
+        </div>
+      </aside>
+
+      <section className="miu-main">
+        {browsing ? (
+          <ChannelBrowser
+            onJoined={(threadId) => {
+              refetch();
+              pick(threadId);
+            }}
+          />
+        ) : composing ? (
+          <NewConversation
+            onCreated={(threadId) => {
+              refetch();
+              pick(threadId);
+            }}
+          />
+        ) : (
+          <Thread threadId={selected} activeRootId={activeRoot} onOpenThread={setActiveRoot} />
+        )}
+      </section>
+
+      {!browsing && !composing && selected && activeRoot ? (
+        <ThreadPane threadId={selected} rootId={activeRoot} onClose={() => setActiveRoot(null)} />
+      ) : null}
+    </div>
+  );
+}
diff --git a/packages/iios-messaging-ui/src/components/modal-portal.tsx b/packages/iios-messaging-ui/src/components/modal-portal.tsx
new file mode 100644
index 0000000..9e79dbb
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/modal-portal.tsx
@@ -0,0 +1,35 @@
+import { useState, type ReactNode, type CSSProperties } from 'react';
+import { createPortal } from 'react-dom';
+
+// The SDK theme tokens. A body-portaled node is outside the `.miu-messenger`/`.miu-inbox`
+// subtree that defines these, so we copy their resolved values onto the portal root.
+const THEME_VARS = [
+  '--miu-bg', '--miu-panel', '--miu-panel-2', '--miu-border',
+  '--miu-text', '--miu-muted', '--miu-accent', '--miu-accent-text', '--miu-radius',
+] as const;
+
+function copyThemeVars(): Record<string, string> {
+  if (typeof document === 'undefined') return {};
+  const src = document.querySelector('.miu-messenger, .miu-inbox');
+  if (!src) return {};
+  const cs = getComputedStyle(src);
+  const out: Record<string, string> = {};
+  for (const v of THEME_VARS) {
+    const val = cs.getPropertyValue(v).trim();
+    if (val) out[v] = val;
+  }
+  return out;
+}
+
+/**
+ * Render an overlay into document.body so it escapes the host's stacking context and overflow.
+ * A host wrapper like `.view { position: relative; z-index: 1 }` traps a `position: fixed` overlay
+ * BELOW a sibling sticky header no matter how high its z-index — the only robust fix is to leave
+ * that stacking context entirely. Theme tokens are copied from the live surface (captured once on
+ * mount, synchronously, so there is no unstyled first paint) and re-applied on the portal root.
+ */
+export function ModalPortal({ children }: { children: ReactNode }) {
+  const [vars] = useState<Record<string, string>>(copyThemeVars);
+  if (typeof document === 'undefined') return null;
+  return createPortal(<div className="miu-portal" style={vars as CSSProperties}>{children}</div>, document.body);
+}
diff --git a/packages/iios-messaging-ui/src/components/new-conversation.test.tsx b/packages/iios-messaging-ui/src/components/new-conversation.test.tsx
new file mode 100644
index 0000000..ab26ccd
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/new-conversation.test.tsx
@@ -0,0 +1,66 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { MessagingProvider } from '../provider';
+import { MockAdapter } from '../adapters/mock';
+import { Messenger } from './messenger';
+
+function mount(adapter = new MockAdapter()) {
+  render(
+    <MessagingProvider adapter={adapter}>
+      <Messenger />
+    </MessagingProvider>,
+  );
+  return adapter;
+}
+
+describe('MockAdapter directory + openThread', () => {
+  it('directory lists people you can message', async () => {
+    const a = new MockAdapter();
+    const people = await a.directory();
+    expect(people.some((p) => p.name === 'Dan Whitaker')).toBe(true);
+  });
+
+  it('one participant opens a dm; two+ open a group with a subject', async () => {
+    const a = new MockAdapter();
+    const dm = await a.openThread({ participantIds: ['pp_dan'], membership: 'dm' });
+    const list = await a.listConversations();
+    expect(list.find((c) => c.threadId === dm.threadId)?.membership).toBe('dm');
+
+    const group = await a.openThread({ participantIds: ['pp_dan', 'pp_priya'], membership: 'group', subject: 'Roof crew' });
+    const g = (await a.listConversations()).find((c) => c.threadId === group.threadId);
+    expect(g?.membership).toBe('group');
+    expect(g?.title).toBe('Roof crew');
+  });
+
+  it('opening a dm with the same person reuses the existing thread', async () => {
+    const a = new MockAdapter();
+    const first = await a.openThread({ participantIds: ['pp_priya'], membership: 'dm' });
+    const second = await a.openThread({ participantIds: ['pp_priya'], membership: 'dm' });
+    expect(second.threadId).toBe(first.threadId);
+  });
+});
+
+describe('<Messenger /> new conversation flow', () => {
+  it('opens the picker from the Direct messages +, and starting a chat leaves the picker', async () => {
+    mount();
+    // Open the "New message" picker.
+    fireEvent.click(await screen.findByTitle('New message'));
+    expect(await screen.findByText('New message')).toBeTruthy();
+
+    // Pick a person and start a DM.
+    fireEvent.click(await screen.findByText('Dan Whitaker'));
+    fireEvent.click(screen.getByText('Start chat'));
+
+    // The picker closes (we're back in a thread view — the picker heading is gone).
+    await waitFor(() => expect(screen.queryByText('Start chat')).toBeNull());
+  });
+
+  it('selecting two people switches the action to group create', async () => {
+    mount();
+    fireEvent.click(await screen.findByTitle('New message'));
+    fireEvent.click(await screen.findByText('Dan Whitaker'));
+    fireEvent.click(await screen.findByText('Priya Nair'));
+    expect(screen.getByText(/Create group \(2\)/)).toBeTruthy();
+    expect(screen.getByLabelText('Group name')).toBeTruthy();
+  });
+});
diff --git a/packages/iios-messaging-ui/src/components/new-conversation.tsx b/packages/iios-messaging-ui/src/components/new-conversation.tsx
new file mode 100644
index 0000000..2436c8a
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/new-conversation.tsx
@@ -0,0 +1,97 @@
+import { useEffect, useState } from 'react';
+import { useAdapter } from '../provider';
+import type { Person } from '../types';
+
+/**
+ * Start a direct message or a group — Slack-style. Pick people from the org directory: one selected
+ * opens a DM (deduped by the adapter), two or more create a group with an optional name. Shown in
+ * the main pane like the channel browser.
+ */
+export function NewConversation({ onCreated }: { onCreated?: (threadId: string) => void }) {
+  const adapter = useAdapter();
+  const [people, setPeople] = useState<Person[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [q, setQ] = useState('');
+  const [selected, setSelected] = useState<string[]>([]);
+  const [name, setName] = useState('');
+  const [busy, setBusy] = useState(false);
+
+  useEffect(() => {
+    if (!adapter.directory) {
+      setLoading(false);
+      return;
+    }
+    let alive = true;
+    adapter
+      .directory()
+      .then((p) => {
+        if (alive) {
+          setPeople(p);
+          setError(null);
+        }
+      })
+      .catch((e: unknown) => {
+        if (alive) setError(e instanceof Error ? e.message : String(e));
+      })
+      .finally(() => {
+        if (alive) setLoading(false);
+      });
+    return () => {
+      alive = false;
+    };
+  }, [adapter]);
+
+  const filtered = people.filter((p) => p.name.toLowerCase().includes(q.trim().toLowerCase()));
+  const isGroup = selected.length > 1;
+  const canStart = selected.length >= 1 && !busy;
+
+  function toggle(id: string): void {
+    setSelected((s) => (s.includes(id) ? s.filter((x) => x !== id) : [...s, id]));
+  }
+
+  async function start(): Promise<void> {
+    if (!canStart) return;
+    setBusy(true);
+    setError(null);
+    try {
+      const res = await adapter.openThread({
+        participantIds: selected,
+        membership: isGroup ? 'group' : 'dm',
+        ...(isGroup && name.trim() ? { subject: name.trim() } : {}),
+      });
+      onCreated?.(res.threadId);
+    } catch (e) {
+      setError(e instanceof Error ? e.message : String(e));
+    } finally {
+      setBusy(false);
+    }
+  }
+
+  return (
+    <div className="miu-browser">
+      <div className="miu-browser-head">New message</div>
+      <div className="miu-newconv">
+        <input className="miu-input" value={q} onChange={(e) => setQ(e.target.value)} placeholder="Search people…" aria-label="Search people" />
+        {isGroup ? (
+          <input className="miu-input" value={name} onChange={(e) => setName(e.target.value)} placeholder="Group name (optional)" aria-label="Group name" />
+        ) : null}
+        {error ? <div className="miu-empty miu-error">{error}</div> : null}
+        <div className="miu-browser-list">
+          {loading && people.length === 0 ? <div className="miu-empty">Loading…</div> : null}
+          {!loading && filtered.length === 0 ? <div className="miu-empty">No people found.</div> : null}
+          {filtered.map((p) => (
+            <label key={p.id} className={`miu-person-row${selected.includes(p.id) ? ' is-active' : ''}`}>
+              <input type="checkbox" checked={selected.includes(p.id)} onChange={() => toggle(p.id)} />
+              <span className="miu-browser-name">{p.name}</span>
+              <span className="miu-pill">{p.kind}</span>
+            </label>
+          ))}
+        </div>
+        <button type="button" className="miu-send" onClick={() => void start()} disabled={!canStart}>
+          {busy ? 'Starting…' : isGroup ? `Create group (${selected.length})` : 'Start chat'}
+        </button>
+      </div>
+    </div>
+  );
+}
diff --git a/packages/iios-messaging-ui/src/components/thread-pane.test.tsx b/packages/iios-messaging-ui/src/components/thread-pane.test.tsx
new file mode 100644
index 0000000..6cea6d3
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/thread-pane.test.tsx
@@ -0,0 +1,36 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { MessagingProvider } from '../provider';
+import { Messenger } from './messenger';
+import { MockAdapter } from '../adapters/mock';
+
+function mount() {
+  return render(
+    <MessagingProvider adapter={new MockAdapter()}>
+      <Messenger />
+    </MessagingProvider>,
+  );
+}
+
+describe('Slack-style thread pane', () => {
+  it('opens a thread on 💬, posts a reply into it, and shows the reply count on the parent', async () => {
+    mount();
+    // Wait for the auto-selected thread's message to render WITH its actions (not just the sidebar
+    // preview), then open the thread pane via the message's reply affordance (💬).
+    const replyButtons = await screen.findAllByTitle('Reply in thread');
+    fireEvent.click(replyButtons[0]!);
+    expect(await screen.findByText('Thread')).toBeTruthy(); // pane header
+
+    // The pane's composer (placeholder "Reply…") — send a threaded reply.
+    const replyInput = screen.getByPlaceholderText('Reply…') as HTMLInputElement;
+    fireEvent.change(replyInput, { target: { value: 'on it' } });
+    // The pane has its own Send; grab the last one (pane is rendered after the main composer).
+    const sends = screen.getAllByText('Send');
+    fireEvent.click(sends[sends.length - 1]!);
+
+    // The reply shows in the pane (replies are hidden from the main thread, so this is unique)...
+    await waitFor(() => expect(screen.getByText('on it')).toBeTruthy());
+    // ...and the parent now advertises the reply count as a thread-link button in the main thread.
+    await waitFor(() => expect(screen.getByRole('button', { name: /1 reply/ })).toBeTruthy());
+  });
+});
diff --git a/packages/iios-messaging-ui/src/components/thread-pane.tsx b/packages/iios-messaging-ui/src/components/thread-pane.tsx
new file mode 100644
index 0000000..7252dca
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/thread-pane.tsx
@@ -0,0 +1,60 @@
+import { useMemo } from 'react';
+import { useMessages } from '../hooks/use-messages';
+import { useMembers } from '../hooks/use-members';
+import { Composer } from './composer';
+import { MessageItem } from './message-item';
+
+/**
+ * The Slack-style thread side panel: the root message + its replies + a composer that posts back
+ * into the thread (parentInteractionId = root). Uses its own useMessages on the same thread; the
+ * shared adapter subscription keeps it and the main view in sync.
+ */
+export function ThreadPane({
+  threadId,
+  rootId,
+  onClose,
+}: {
+  threadId: string;
+  rootId: string;
+  onClose: () => void;
+}) {
+  const { messages, send, react, upload, seenIds, sendTyping, canReact, canUpload } = useMessages(threadId);
+  const members = useMembers(threadId);
+  const memberNames = useMemo(() => members.map((m) => m.name), [members]);
+
+  const root = useMemo(() => messages.find((m) => m.id === rootId), [messages, rootId]);
+  const replies = useMemo(() => messages.filter((m) => m.parentInteractionId === rootId), [messages, rootId]);
+
+  return (
+    <aside className="miu-pane">
+      <header className="miu-pane-head">
+        <span>Thread</span>
+        <button type="button" className="miu-pane-close" onClick={onClose} aria-label="Close thread">
+          ✕
+        </button>
+      </header>
+
+      <div className="miu-messages miu-pane-messages">
+        {root ? (
+          <MessageItem message={root} memberNames={memberNames} canReact={canReact} onReact={(id, e) => void react(id, e)} seen={seenIds.has(root.id)} />
+        ) : (
+          <div className="miu-empty">Message not found.</div>
+        )}
+        <div className="miu-pane-divider">{replies.length} {replies.length === 1 ? 'reply' : 'replies'}</div>
+        {replies.map((m) => (
+          <MessageItem key={m.id} message={m} memberNames={memberNames} canReact={canReact} onReact={(id, e) => void react(id, e)} seen={seenIds.has(m.id)} />
+        ))}
+      </div>
+
+      <Composer
+        members={members}
+        canUpload={canUpload}
+        upload={upload}
+        onSend={send}
+        onTyping={sendTyping}
+        parentInteractionId={rootId}
+        placeholder="Reply…"
+      />
+    </aside>
+  );
+}
diff --git a/packages/iios-messaging-ui/src/components/thread.tsx b/packages/iios-messaging-ui/src/components/thread.tsx
new file mode 100644
index 0000000..0f21efa
--- /dev/null
+++ b/packages/iios-messaging-ui/src/components/thread.tsx
@@ -0,0 +1,61 @@
+import { useMemo } from 'react';
+import { useMessages } from '../hooks/use-messages';
+import { useMembers } from '../hooks/use-members';
+import { Composer } from './composer';
+import { MessageItem } from './message-item';
+
+/**
+ * The main conversation view: top-level messages + composer. Replies (messages with a
+ * parentInteractionId) are hidden here and live in the ThreadPane — a message with replies shows a
+ * "N replies" link that opens it. @mentions, reactions, and attachments all work.
+ */
+export function Thread({
+  threadId,
+  activeRootId,
+  onOpenThread,
+}: {
+  threadId: string | null;
+  activeRootId?: string | null;
+  onOpenThread?: (rootId: string) => void;
+}) {
+  const { messages, loading, error, send, react, upload, typingUserIds, seenIds, sendTyping, canReact, canUpload } = useMessages(threadId);
+  const members = useMembers(threadId);
+  const memberNames = useMemo(() => members.map((m) => m.name), [members]);
+
+  const topLevel = useMemo(() => messages.filter((m) => !m.parentInteractionId), [messages]);
+  const replyCount = useMemo(() => {
+    const counts = new Map<string, number>();
+    for (const m of messages) if (m.parentInteractionId) counts.set(m.parentInteractionId, (counts.get(m.parentInteractionId) ?? 0) + 1);
+    return counts;
+  }, [messages]);
+
+  if (!threadId) {
+    return <div className="miu-empty miu-thread-empty">Select a conversation.</div>;
+  }
+
+  return (
+    <div className={`miu-thread${activeRootId ? ' has-pane' : ''}`}>
+      <div className="miu-messages">
+        {loading && messages.length === 0 ? <div className="miu-empty">Loading…</div> : null}
+        {error ? <div className="miu-empty miu-error">{error}</div> : null}
+        {topLevel.map((m) => (
+          <MessageItem
+            key={m.id}
+            message={m}
+            memberNames={memberNames}
+            canReact={canReact}
+            onReact={(id, emoji) => void react(id, emoji)}
+            seen={seenIds.has(m.id)}
+            replyCount={replyCount.get(m.id) ?? 0}
+            {...(onOpenThread ? { onOpenThread } : {})}
+          />
+        ))}
+        {typingUserIds.length > 0 ? (
+          <div className="miu-typing">{typingUserIds.length === 1 ? 'typing…' : 'several people are typing…'}</div>
+        ) : null}
+      </div>
+
+      <Composer members={members} canUpload={canUpload} upload={upload} onSend={send} onTyping={sendTyping} />
+    </div>
+  );
+}
diff --git a/packages/iios-messaging-ui/src/conformance.test.ts b/packages/iios-messaging-ui/src/conformance.test.ts
new file mode 100644
index 0000000..bef335a
--- /dev/null
+++ b/packages/iios-messaging-ui/src/conformance.test.ts
@@ -0,0 +1,8 @@
+import { runAdapterConformance } from './conformance';
+import { MockAdapter } from './adapters/mock';
+
+runAdapterConformance({
+  makeAdapter: () => new MockAdapter(),
+  seededThreadId: 'th_mock_1',
+  openWith: ['pp_sofia'],
+});
diff --git a/packages/iios-messaging-ui/src/conformance.ts b/packages/iios-messaging-ui/src/conformance.ts
new file mode 100644
index 0000000..8b397fb
--- /dev/null
+++ b/packages/iios-messaging-ui/src/conformance.ts
@@ -0,0 +1,112 @@
+import { describe, it, expect } from 'vitest';
+import type { MessagingAdapter } from './adapter';
+import type { MessageEvent } from './types';
+
+export interface ConformanceOptions {
+  /** Build a fresh, isolated adapter per test. */
+  makeAdapter: () => Promise<MessagingAdapter> | MessagingAdapter;
+  /** A thread id that exists in the fixture. */
+  seededThreadId: string;
+  /** Participant ids openThread can legally be called with. */
+  openWith: string[];
+}
+
+/**
+ * The definition of a correct MessagingAdapter. Every adapter runs this.
+ *
+ * Imports vitest, so it ships from the './conformance' subpath ONLY and is never
+ * reachable from the main barrel. Consumers supply their own vitest.
+ *
+ * Usage from another package:
+ *   import { runAdapterConformance } from '@insignia/iios-messaging-ui/conformance';
+ *   runAdapterConformance({ makeAdapter: () => new MockAdapter(), seededThreadId: 'th_1', openWith: ['pp_a'] });
+ */
+export function runAdapterConformance(opts: ConformanceOptions): void {
+  const make = async () => await opts.makeAdapter();
+
+  describe('MessagingAdapter conformance', () => {
+    it('lists conversations', async () => {
+      const a = await make();
+      const list = await a.listConversations();
+      expect(Array.isArray(list)).toBe(true);
+    });
+
+    it('returns history for a seeded thread', async () => {
+      const a = await make();
+      const msgs = await a.history(opts.seededThreadId);
+      expect(Array.isArray(msgs)).toBe(true);
+    });
+
+    it('send resolves with a message carrying the sent text and a stable id', async () => {
+      const a = await make();
+      const m = await a.send(opts.seededThreadId, 'conformance hello');
+      expect(m.text).toBe('conformance hello');
+      expect(typeof m.id).toBe('string');
+      expect(m.id.length).toBeGreaterThan(0);
+    });
+
+    it('a sent message is attributed to the current actor', async () => {
+      const a = await make();
+      const m = await a.send(opts.seededThreadId, 'whose is this');
+      expect(m.actorId).toBe(a.currentActorId());
+    });
+
+    it('currentActorId is known BEFORE any message is sent', async () => {
+      // The bug this SDK exists to kill: identity must come from auth, never be
+      // inferred from history. A fresh adapter already knows who you are.
+      const a = await make();
+      expect(a.currentActorId()).not.toBeNull();
+    });
+
+    it('a sent message appears in history', async () => {
+      const a = await make();
+      await a.send(opts.seededThreadId, 'persist me');
+      const msgs = await a.history(opts.seededThreadId);
+      expect(msgs.some((m) => m.text === 'persist me')).toBe(true);
+    });
+
+    it('subscribe delivers a message event on send', async () => {
+      const a = await make();
+      const seen: MessageEvent[] = [];
+      const off = a.subscribe(opts.seededThreadId, (e) => seen.push(e));
+      await a.send(opts.seededThreadId, 'live one');
+      off();
+      const msgs = seen.filter((e) => e.kind === 'message');
+      expect(msgs.length).toBeGreaterThan(0);
+    });
+
+    it('unsubscribe stops delivery', async () => {
+      const a = await make();
+      const seen: MessageEvent[] = [];
+      const off = a.subscribe(opts.seededThreadId, (e) => seen.push(e));
+      off();
+      await a.send(opts.seededThreadId, 'should not be heard');
+      expect(seen).toHaveLength(0);
+    });
+
+    it('unsubscribe is idempotent', async () => {
+      const a = await make();
+      const off = a.subscribe(opts.seededThreadId, () => {});
+      off();
+      expect(() => off()).not.toThrow();
+    });
+
+    it('openThread returns a thread id', async () => {
+      const a = await make();
+      const { threadId } = await a.openThread({ participantIds: opts.openWith });
+      expect(typeof threadId).toBe('string');
+      expect(threadId.length).toBeGreaterThan(0);
+    });
+
+    it('markRead resolves', async () => {
+      const a = await make();
+      const m = await a.send(opts.seededThreadId, 'read me');
+      await expect(a.markRead(opts.seededThreadId, m.id)).resolves.toBeUndefined();
+    });
+
+    it('sendTyping does not throw', async () => {
+      const a = await make();
+      expect(() => a.sendTyping(opts.seededThreadId)).not.toThrow();
+    });
+  });
+}
diff --git a/packages/iios-messaging-ui/src/hooks/use-channels.ts b/packages/iios-messaging-ui/src/hooks/use-channels.ts
new file mode 100644
index 0000000..de47e3d
--- /dev/null
+++ b/packages/iios-messaging-ui/src/hooks/use-channels.ts
@@ -0,0 +1,84 @@
+import { useCallback, useEffect, useState } from 'react';
+import { useAdapter } from '../provider';
+import type { ChannelSummary, CreateChannelInput } from '../types';
+
+export interface ChannelsState {
+  /** Discoverable channels (public + private-I'm-in), each flagged `joined`. */
+  browsable: ChannelSummary[];
+  loading: boolean;
+  error: string | null;
+  /** Whether the adapter implements channels at all — drives showing/hiding the channels UI. */
+  supported: boolean;
+  refetch: () => void;
+  create: (input: CreateChannelInput) => Promise<string>;
+  join: (threadId: string) => Promise<void>;
+  leave: (threadId: string) => Promise<void>;
+}
+
+export function useChannels(): ChannelsState {
+  const adapter = useAdapter();
+  const supported = typeof adapter.browseChannels === 'function';
+  const [browsable, setBrowsable] = useState<ChannelSummary[]>([]);
+  const [loading, setLoading] = useState(supported);
+  const [error, setError] = useState<string | null>(null);
+  const [nonce, setNonce] = useState(0);
+
+  useEffect(() => {
+    if (!adapter.browseChannels) {
+      setLoading(false);
+      return;
+    }
+    let alive = true;
+    setLoading(true);
+    adapter
+      .browseChannels()
+      .then((list) => {
+        if (!alive) return;
+        setBrowsable(list);
+        setError(null);
+      })
+      .catch((e: unknown) => {
+        if (!alive) return;
+        setError(e instanceof Error ? e.message : String(e));
+        setBrowsable([]);
+      })
+      .finally(() => {
+        if (alive) setLoading(false);
+      });
+    return () => {
+      alive = false;
+    };
+  }, [adapter, nonce]);
+
+  const refetch = useCallback(() => setNonce((n) => n + 1), []);
+
+  const create = useCallback(
+    async (input: CreateChannelInput) => {
+      if (!adapter.createChannel) throw new Error('channels not supported by this adapter');
+      const { threadId } = await adapter.createChannel(input);
+      setNonce((n) => n + 1);
+      return threadId;
+    },
+    [adapter],
+  );
+
+  const join = useCallback(
+    async (threadId: string) => {
+      if (!adapter.joinChannel) throw new Error('channels not supported by this adapter');
+      await adapter.joinChannel(threadId);
+      setNonce((n) => n + 1);
+    },
+    [adapter],
+  );
+
+  const leave = useCallback(
+    async (threadId: string) => {
+      if (!adapter.leaveChannel) throw new Error('channels not supported by this adapter');
+      await adapter.leaveChannel(threadId);
+      setNonce((n) => n + 1);
+    },
+    [adapter],
+  );
+
+  return { browsable, loading, error, supported, refetch, create, join, leave };
+}
diff --git a/packages/iios-messaging-ui/src/hooks/use-conversations.test.tsx b/packages/iios-messaging-ui/src/hooks/use-conversations.test.tsx
new file mode 100644
index 0000000..8413071
--- /dev/null
+++ b/packages/iios-messaging-ui/src/hooks/use-conversations.test.tsx
@@ -0,0 +1,50 @@
+import { describe, it, expect, vi } from 'vitest';
+import { renderHook, waitFor, act } from '@testing-library/react';
+import type { ReactNode } from 'react';
+import { MessagingProvider } from '../provider';
+import { MockAdapter } from '../adapters/mock';
+import { useConversations } from './use-conversations';
+import type { MessagingAdapter } from '../adapter';
+
+const wrap = (adapter: MessagingAdapter) =>
+  function Wrapper({ children }: { children: ReactNode }) {
+    return <MessagingProvider adapter={adapter}>{children}</MessagingProvider>;
+  };
+
+describe('useConversations', () => {
+  it('starts loading, then resolves the adapter list', async () => {
+    const { result } = renderHook(() => useConversations(), { wrapper: wrap(new MockAdapter()) });
+    expect(result.current.loading).toBe(true);
+
+    await waitFor(() => expect(result.current.loading).toBe(false));
+    // 2 DMs/groups + 2 channels I'm a member of (the un-joined public channel is browse-only).
+    expect(result.current.conversations).toHaveLength(4);
+    expect(result.current.conversations[0]!.threadId).toBe('th_mock_1');
+    expect(result.current.error).toBeNull();
+  });
+
+  it('surfaces adapter failure as error state and never throws', async () => {
+    const adapter = new MockAdapter();
+    vi.spyOn(adapter, 'listConversations').mockRejectedValue(new Error('data door down'));
+
+    const { result } = renderHook(() => useConversations(), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+    expect(result.current.error).toBe('data door down');
+    expect(result.current.conversations).toEqual([]);
+  });
+
+  it('refetch picks up newly opened threads', async () => {
+    const adapter = new MockAdapter();
+    const { result } = renderHook(() => useConversations(), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.conversations).toHaveLength(4));
+
+    await act(async () => {
+      await adapter.openThread({ participantIds: ['pp_dan'] });
+    });
+    await act(async () => {
+      result.current.refetch();
+    });
+
+    await waitFor(() => expect(result.current.conversations).toHaveLength(5));
+  });
+});
diff --git a/packages/iios-messaging-ui/src/hooks/use-conversations.ts b/packages/iios-messaging-ui/src/hooks/use-conversations.ts
new file mode 100644
index 0000000..f8507eb
--- /dev/null
+++ b/packages/iios-messaging-ui/src/hooks/use-conversations.ts
@@ -0,0 +1,45 @@
+import { useCallback, useEffect, useState } from 'react';
+import { useAdapter } from '../provider';
+import type { Conversation } from '../types';
+
+export interface ConversationsState {
+  conversations: Conversation[];
+  loading: boolean;
+  error: string | null;
+  refetch: () => void;
+}
+
+export function useConversations(): ConversationsState {
+  const adapter = useAdapter();
+  const [conversations, setConversations] = useState<Conversation[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [nonce, setNonce] = useState(0);
+
+  useEffect(() => {
+    let alive = true;
+    setLoading(true);
+    adapter
+      .listConversations()
+      .then((list) => {
+        if (!alive) return;
+        setConversations(list);
+        setError(null);
+      })
+      .catch((e: unknown) => {
+        if (!alive) return;
+        setError(e instanceof Error ? e.message : String(e));
+        setConversations([]);
+      })
+      .finally(() => {
+        if (alive) setLoading(false);
+      });
+    return () => {
+      alive = false;
+    };
+  }, [adapter, nonce]);
+
+  const refetch = useCallback(() => setNonce((n) => n + 1), []);
+
+  return { conversations, loading, error, refetch };
+}
diff --git a/packages/iios-messaging-ui/src/hooks/use-members.ts b/packages/iios-messaging-ui/src/hooks/use-members.ts
new file mode 100644
index 0000000..cd46f70
--- /dev/null
+++ b/packages/iios-messaging-ui/src/hooks/use-members.ts
@@ -0,0 +1,31 @@
+import { useEffect, useState } from 'react';
+import { useAdapter } from '../provider';
+import type { Person } from '../types';
+
+/** A thread's members (for @mention autocomplete + highlighting). Empty if the adapter
+ *  doesn't implement listMembers, or while loading. */
+export function useMembers(threadId: string | null): Person[] {
+  const adapter = useAdapter();
+  const [members, setMembers] = useState<Person[]>([]);
+
+  useEffect(() => {
+    if (!threadId || !adapter.listMembers) {
+      setMembers([]);
+      return;
+    }
+    let alive = true;
+    adapter
+      .listMembers(threadId)
+      .then((m) => {
+        if (alive) setMembers(m);
+      })
+      .catch(() => {
+        if (alive) setMembers([]);
+      });
+    return () => {
+      alive = false;
+    };
+  }, [adapter, threadId]);
+
+  return members;
+}
diff --git a/packages/iios-messaging-ui/src/hooks/use-messages.test.tsx b/packages/iios-messaging-ui/src/hooks/use-messages.test.tsx
new file mode 100644
index 0000000..f6d0771
--- /dev/null
+++ b/packages/iios-messaging-ui/src/hooks/use-messages.test.tsx
@@ -0,0 +1,160 @@
+import { describe, it, expect, vi } from 'vitest';
+import { renderHook, waitFor, act } from '@testing-library/react';
+import type { ReactNode } from 'react';
+import { MessagingProvider } from '../provider';
+import { MockAdapter } from '../adapters/mock';
+import { useMessages } from './use-messages';
+import type { MessagingAdapter } from '../adapter';
+import type { Message } from '../types';
+
+const wrap = (adapter: MessagingAdapter) =>
+  function Wrapper({ children }: { children: ReactNode }) {
+    return <MessagingProvider adapter={adapter}>{children}</MessagingProvider>;
+  };
+
+describe('useMessages', () => {
+  it('loads history for the thread', async () => {
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(new MockAdapter()) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+    expect(result.current.messages).toHaveLength(1);
+    expect(result.current.messages[0]!.text).toBe('Can you review the Henderson estimate?');
+  });
+
+  // REGRESSION: the CRM inferred actor identity by scanning for a sent message, so
+  // before you had spoken in a thread EVERY message rendered as not-yours.
+  it('marks ownership correctly before the user has sent anything', async () => {
+    const adapter = new MockAdapter();
+    await adapter.send('th_mock_1', 'an earlier message of mine');
+
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.messages).toHaveLength(2));
+
+    // Never sent anything via the hook — ownership still resolves from currentActorId().
+    expect(result.current.messages[0]!.mine).toBe(false); // from pp_sofia
+    expect(result.current.messages[1]!.mine).toBe(true); // from me
+  });
+
+  it('appends an optimistic message immediately on send', async () => {
+    const adapter = new MockAdapter();
+    let release!: () => void;
+    vi.spyOn(adapter, 'send').mockImplementation(
+      () => new Promise((res) => { release = () => res({ id: 'srv_1', actorId: 'me', text: 'hi', at: '2026-07-17T10:00:00.000Z' }); }),
+    );
+
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+
+    act(() => { void result.current.send('hi'); });
+
+    await waitFor(() => expect(result.current.messages).toHaveLength(2));
+    expect(result.current.messages[1]!.pending).toBe(true);
+    expect(result.current.messages[1]!.mine).toBe(true);
+
+    await act(async () => { release(); });
+    await waitFor(() => expect(result.current.messages[1]!.pending).toBeFalsy());
+  });
+
+  it('rolls back the optimistic message and reports error when send fails', async () => {
+    const adapter = new MockAdapter();
+    vi.spyOn(adapter, 'send').mockRejectedValue(new Error('offline'));
+
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+
+    await act(async () => {
+      await expect(result.current.send('doomed')).rejects.toThrow('offline');
+    });
+
+    expect(result.current.messages).toHaveLength(1);
+    expect(result.current.messages.some((m) => m.text === 'doomed')).toBe(false);
+    expect(result.current.error).toBe('offline');
+  });
+
+  it('does not duplicate a message when the transport echoes it back', async () => {
+    const adapter = new MockAdapter();
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+
+    // MockAdapter.send emits a 'message' event AND resolves with the same message.
+    await act(async () => { await result.current.send('echo once'); });
+
+    expect(result.current.messages.filter((m) => m.text === 'echo once')).toHaveLength(1);
+  });
+
+  it('collects typing user ids from subscribe events', async () => {
+    const adapter = new MockAdapter();
+    let emit!: (userId: string) => void;
+    vi.spyOn(adapter, 'subscribe').mockImplementation((_t, cb) => {
+      emit = (userId) => cb({ kind: 'typing', userId });
+      return () => {};
+    });
+
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+
+    act(() => emit('pp_sofia'));
+    expect(result.current.typingUserIds).toEqual(['pp_sofia']);
+  });
+
+  it('unsubscribes on unmount', async () => {
+    const adapter = new MockAdapter();
+    const off = vi.fn();
+    vi.spyOn(adapter, 'subscribe').mockReturnValue(off);
+
+    const { unmount, result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+    await waitFor(() => expect(result.current.loading).toBe(false));
+    unmount();
+
+    expect(off).toHaveBeenCalled();
+  });
+
+  it('keeps a live message that arrives before history resolves', async () => {
+    const adapter = new MockAdapter();
+    let resolveHistory!: (msgs: Message[]) => void;
+    vi.spyOn(adapter, 'history').mockImplementation(
+      () => new Promise<Message[]>((res) => { resolveHistory = res; }),
+    );
+    let emit!: (m: Message) => void;
+    vi.spyOn(adapter, 'subscribe').mockImplementation((_t, cb) => {
+      emit = (m) => cb({ kind: 'message', message: m });
+      return () => {};
+    });
+
+    const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+
+    // A live message arrives while history() is still pending.
+    act(() => emit({ id: 'live_1', actorId: 'pp_sofia', text: 'ping before history', at: '2026-07-17T10:00:00.000Z' }));
+
+    // History resolves afterwards with an older message.
+    await act(async () => {
+      resolveHistory([{ id: 'hist_1', actorId: 'pp_sofia', text: 'older', at: '2026-07-17T09:00:00.000Z' }]);
+    });
+
+    const texts = result.current.messages.map((m) => m.text);
+    expect(texts).toContain('older');
+    expect(texts).toContain('ping before history'); // must NOT be clobbered by history load
+  });
+
+  it('clears a typing indicator after its TTL elapses', async () => {
+    vi.useFakeTimers();
+    try {
+      const adapter = new MockAdapter();
+      let emit!: (userId: string) => void;
+      vi.spyOn(adapter, 'subscribe').mockImplementation((_t, cb) => {
+        emit = (userId) => cb({ kind: 'typing', userId });
+        return () => {};
+      });
+
+      const { result } = renderHook(() => useMessages('th_mock_1'), { wrapper: wrap(adapter) });
+      await act(async () => { await vi.advanceTimersByTimeAsync(0); }); // flush history microtask
+
+      act(() => emit('pp_sofia'));
+      expect(result.current.typingUserIds).toEqual(['pp_sofia']);
+
+      await act(async () => { await vi.advanceTimersByTimeAsync(3600); });
+      expect(result.current.typingUserIds).toEqual([]);
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+});
diff --git a/packages/iios-messaging-ui/src/hooks/use-messages.ts b/packages/iios-messaging-ui/src/hooks/use-messages.ts
new file mode 100644
index 0000000..ccb49a6
--- /dev/null
+++ b/packages/iios-messaging-ui/src/hooks/use-messages.ts
@@ -0,0 +1,215 @@
+import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
+import { useAdapter } from '../provider';
+import { isOwnMessage } from '../types';
+import type { Attachment, Message, SendOpts } from '../types';
+
+const TYPING_TTL_MS = 3500;
+
+export interface UiMessage extends Message {
+  mine: boolean;
+}
+
+export interface MessagesState {
+  messages: UiMessage[];
+  loading: boolean;
+  error: string | null;
+  send: (content: string, opts?: SendOpts) => Promise<void>;
+  react: (messageId: string, emoji: string) => Promise<void>;
+  upload: (file: File) => Promise<Attachment>;
+  typingUserIds: string[];
+  seenIds: Set<string>;
+  sendTyping: () => void;
+  canReact: boolean;
+  canUpload: boolean;
+}
+
+let optimisticSeq = 0;
+
+export function useMessages(threadId: string | null): MessagesState {
+  const adapter = useAdapter();
+  const [raw, setRaw] = useState<Message[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [typing, setTyping] = useState<Record<string, number>>({});
+  const [seenIds, setSeenIds] = useState<Set<string>>(new Set());
+
+  const currentActorId = adapter.currentActorId();
+  const actorRef = useRef(currentActorId);
+  actorRef.current = currentActorId;
+
+  // Load history, then subscribe. Reconciliation is by message id, so an echoed
+  // send never duplicates the optimistic row.
+  useEffect(() => {
+    if (!threadId) {
+      setRaw([]);
+      setLoading(false);
+      return;
+    }
+    let alive = true;
+    setLoading(true);
+    setRaw([]);
+    setError(null);
+    setSeenIds(new Set());
+    setTyping({});
+
+    adapter
+      .history(threadId)
+      .then((h) => {
+        if (!alive) return;
+        // Merge, don't clobber: a live message can arrive via subscribe while this
+        // history fetch is still in flight. Blindly setting raw = h would drop it.
+        setRaw((live) => {
+          const histIds = new Set(h.map((m) => m.id));
+          const extras = live.filter((m) => !histIds.has(m.id));
+          return extras.length ? [...h, ...extras] : h;
+        });
+        setError(null);
+      })
+      .catch((e: unknown) => {
+        if (alive) setError(e instanceof Error ? e.message : String(e));
+      })
+      .finally(() => {
+        if (alive) setLoading(false);
+      });
+
+    const off = adapter.subscribe(threadId, (e) => {
+      if (!alive) return;
+      switch (e.kind) {
+        case 'message':
+          setRaw((l) => (l.some((m) => m.id === e.message.id) ? l : [...l, e.message]));
+          break;
+        case 'typing':
+          if (e.userId !== actorRef.current) {
+            setTyping((t) => ({ ...t, [e.userId]: Date.now() + TYPING_TTL_MS }));
+          }
+          break;
+        case 'receipt':
+          // Only the OTHER side reading my message counts as "seen".
+          if (e.actorId !== actorRef.current) {
+            setSeenIds((s) => (s.has(e.messageId) ? s : new Set(s).add(e.messageId)));
+          }
+          break;
+        case 'reaction':
+          setRaw((l) => l.map((m) => (m.id === e.messageId ? { ...m, reactions: e.reactions } : m)));
+          break;
+      }
+    });
+
+    return () => {
+      alive = false;
+      off();
+    };
+  }, [adapter, threadId]);
+
+  const messages: UiMessage[] = useMemo(
+    () => raw.map((m) => ({ ...m, mine: isOwnMessage(m, currentActorId) })),
+    [raw, currentActorId],
+  );
+
+  const send = useCallback(
+    async (content: string, opts?: SendOpts) => {
+      if (!threadId) return;
+      const tempId = `optimistic_${optimisticSeq++}`;
+      const optimistic: Message = {
+        id: tempId,
+        actorId: actorRef.current,
+        text: content,
+        at: new Date().toISOString(),
+        pending: true,
+        reactions: [],
+        ...(opts?.parentInteractionId ? { parentInteractionId: opts.parentInteractionId } : {}),
+        ...(opts?.attachment ? { attachment: opts.attachment } : {}),
+      };
+      setRaw((l) => [...l, optimistic]);
+
+      try {
+        const saved = await adapter.send(threadId, content, opts);
+        setError(null);
+        // Replace the optimistic row with the server's. If the subscribe echo already
+        // added the real message, just drop the optimistic one.
+        setRaw((l) => {
+          const withoutTemp = l.filter((m) => m.id !== tempId);
+          return withoutTemp.some((m) => m.id === saved.id) ? withoutTemp : [...withoutTemp, saved];
+        });
+      } catch (e: unknown) {
+        setRaw((l) => l.filter((m) => m.id !== tempId));
+        setError(e instanceof Error ? e.message : String(e));
+        throw e;
+      }
+    },
+    [adapter, threadId],
+  );
+
+  const react = useCallback(
+    async (messageId: string, emoji: string) => {
+      if (!threadId || !adapter.react) return;
+      await adapter.react(threadId, messageId, emoji);
+    },
+    [adapter, threadId],
+  );
+
+  const upload = useCallback(
+    async (file: File): Promise<Attachment> => {
+      if (!adapter.upload) throw new Error('uploads are not supported by this adapter');
+      return adapter.upload(file);
+    },
+    [adapter],
+  );
+
+  const sendTyping = useCallback(() => {
+    if (threadId) adapter.sendTyping(threadId);
+  }, [adapter, threadId]);
+
+  // The newest acknowledged (non-pending) message id — what we report as read.
+  const lastReadableId = useMemo(() => {
+    for (let i = raw.length - 1; i >= 0; i--) {
+      if (!raw[i]!.pending) return raw[i]!.id;
+    }
+    return null;
+  }, [raw]);
+
+  // Report my read of the newest message (drives the other side's "seen" tick).
+  // Keyed on the id, not the whole array, so reaction/optimistic churn doesn't re-fire it.
+  useEffect(() => {
+    if (!threadId || !lastReadableId) return;
+    void adapter.markRead(threadId, lastReadableId).catch(() => {});
+  }, [adapter, threadId, lastReadableId]);
+
+  const typingUserIds = useMemo(() => {
+    const now = Date.now();
+    return Object.entries(typing)
+      .filter(([, exp]) => exp > now)
+      .map(([u]) => u);
+  }, [typing]);
+
+  // Expire stale typing entries. Bumping `typing` to a new reference forces the
+  // memo above to recompute with a fresh `now`, dropping entries past their TTL.
+  // (A bump of unrelated state can't do this — the memo is keyed on `typing`, so it
+  // would return its cached array and the indicator would stick forever.)
+  useEffect(() => {
+    if (typingUserIds.length === 0) return;
+    const t = setTimeout(() => setTyping((p) => ({ ...p })), TYPING_TTL_MS);
+    return () => clearTimeout(t);
+  }, [typingUserIds.length, typing]);
+
+  // Only my messages that the other side has read.
+  const seenMine = useMemo(() => {
+    const out = new Set<string>();
+    for (const id of seenIds) if (messages.some((m) => m.id === id && m.mine)) out.add(id);
+    return out;
+  }, [seenIds, messages]);
+
+  return {
+    messages,
+    loading,
+    error,
+    send,
+    react,
+    upload,
+    typingUserIds,
+    seenIds: seenMine,
+    sendTyping,
+    canReact: typeof adapter.react === 'function',
+    canUpload: typeof adapter.upload === 'function',
+  };
+}
diff --git a/packages/iios-messaging-ui/src/inbox/adapter.ts b/packages/iios-messaging-ui/src/inbox/adapter.ts
new file mode 100644
index 0000000..dec547e
--- /dev/null
+++ b/packages/iios-messaging-ui/src/inbox/adapter.ts
@@ -0,0 +1,32 @@
+import type { MailAttachment, InboxItem, InboxState, MailMessage, MailPerson } from './types';
+
+/**
+ * The inbox seam. A host implements this; the SDK renders it. Mirrors MessagingAdapter's philosophy:
+ * `listInbox` returns the UNIFIED feed (work items + mail folded in) so the folding logic lives in
+ * one place (the adapter, which knows both sources). Compose methods are optional and degrade.
+ */
+export interface InboxAdapter {
+  /** The unified inbox: work items + mail threads as rows, filtered by state (mail shows in OPEN). */
+  listInbox(state?: InboxState): Promise<InboxItem[]>;
+
+  /** Transition a work item's state (Done/Snooze/Archive…). Mail rows are not transitioned. */
+  transition(id: string, state: InboxState): Promise<void>;
+
+  /** Messages of one mail thread (HTML + text parts) for the reader. */
+  mailHistory(threadId: string): Promise<MailMessage[]>;
+
+  /** Reply into an existing mail thread, optionally with one attachment. */
+  mailReply(threadId: string, content: string, attachment?: MailAttachment): Promise<void>;
+
+  // ── Attachments (optional) — absent hides the attach affordance ──
+  /** Upload a file to storage, returning a reference to send with a reply/compose. */
+  uploadAttachment?(file: File): Promise<MailAttachment>;
+
+  // ── Compose (optional) — absent hides the "New message" affordance ──
+  /** People you can compose an in-app message to. */
+  directory?(): Promise<MailPerson[]>;
+  /** App-to-app mail (no SMTP) to a registered user's in-app inbox. */
+  composeInternal?(recipientUserId: string, subject: string, text: string, attachments?: MailAttachment[]): Promise<void>;
+  /** External email (SMTP) to an address. */
+  composeExternal?(target: string, subject: string, text: string, attachments?: MailAttachment[]): Promise<void>;
+}
diff --git a/packages/iios-messaging-ui/src/inbox/hooks.ts b/packages/iios-messaging-ui/src/inbox/hooks.ts
new file mode 100644
index 0000000..b9ab6a2
--- /dev/null
+++ b/packages/iios-messaging-ui/src/inbox/hooks.ts
@@ -0,0 +1,174 @@
+import { useCallback, useEffect, useState } from 'react';
+import { useInboxAdapter } from './provider';
+import type { InboxItem, InboxState, MailAttachment, MailMessage, MailPerson } from './types';
+
+export interface InboxData {
+  items: InboxItem[];
+  loading: boolean;
+  error: string | null;
+  transition: (id: string, state: InboxState) => Promise<void>;
+  refetch: () => void;
+}
+
+/** The unified inbox for a given filter state. Refetches when the filter changes. */
+export function useInbox(state?: InboxState): InboxData {
+  const adapter = useInboxAdapter();
+  const [items, setItems] = useState<InboxItem[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [nonce, setNonce] = useState(0);
+
+  useEffect(() => {
+    let alive = true;
+    setLoading(true);
+    adapter
+      .listInbox(state)
+      .then((list) => {
+        if (!alive) return;
+        setItems(list);
+        setError(null);
+      })
+      .catch((e: unknown) => {
+        if (!alive) return;
+        setError(e instanceof Error ? e.message : String(e));
+        setItems([]);
+      })
+      .finally(() => {
+        if (alive) setLoading(false);
+      });
+    return () => {
+      alive = false;
+    };
+  }, [adapter, state, nonce]);
+
+  const refetch = useCallback(() => setNonce((n) => n + 1), []);
+  const transition = useCallback(
+    async (id: string, next: InboxState) => {
+      await adapter.transition(id, next);
+      setNonce((n) => n + 1);
+    },
+    [adapter],
+  );
+
+  return { items, loading, error, transition, refetch };
+}
+
+export interface MailThreadState {
+  messages: MailMessage[];
+  loading: boolean;
+  error: string | null;
+  reply: (content: string, attachment?: MailAttachment) => Promise<void>;
+  canAttach: boolean;
+  upload: (file: File) => Promise<MailAttachment>;
+  refetch: () => void;
+}
+
+/** One mail thread: history + reply. */
+export function useMailThread(threadId: string | null): MailThreadState {
+  const adapter = useInboxAdapter();
+  const [messages, setMessages] = useState<MailMessage[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [nonce, setNonce] = useState(0);
+
+  useEffect(() => {
+    if (!threadId) {
+      setMessages([]);
+      setLoading(false);
+      return;
+    }
+    let alive = true;
+    setLoading(true);
+    adapter
+      .mailHistory(threadId)
+      .then((m) => {
+        if (!alive) return;
+        setMessages(m);
+        setError(null);
+      })
+      .catch((e: unknown) => {
+        if (alive) setError(e instanceof Error ? e.message : String(e));
+      })
+      .finally(() => {
+        if (alive) setLoading(false);
+      });
+    return () => {
+      alive = false;
+    };
+  }, [adapter, threadId, nonce]);
+
+  const refetch = useCallback(() => setNonce((n) => n + 1), []);
+  const reply = useCallback(
+    async (content: string, attachment?: MailAttachment) => {
+      if (!threadId) return;
+      await adapter.mailReply(threadId, content, attachment);
+      setNonce((n) => n + 1);
+    },
+    [adapter, threadId],
+  );
+  const upload = useCallback(
+    async (file: File) => {
+      if (!adapter.uploadAttachment) throw new Error('attachments are not supported by this adapter');
+      return adapter.uploadAttachment(file);
+    },
+    [adapter],
+  );
+
+  return { messages, loading, error, reply, canAttach: typeof adapter.uploadAttachment === 'function', upload, refetch };
+}
+
+export interface ComposeState {
+  supported: boolean;
+  directory: MailPerson[];
+  sendInternal: (recipientUserId: string, subject: string, text: string, attachments?: MailAttachment[]) => Promise<void>;
+  sendExternal: (target: string, subject: string, text: string, attachments?: MailAttachment[]) => Promise<void>;
+  canAttach: boolean;
+  upload: (file: File) => Promise<MailAttachment>;
+}
+
+/** Compose a new message — in-app (to a person) or external (to an email). */
+export function useCompose(): ComposeState {
+  const adapter = useInboxAdapter();
+  const supported = typeof adapter.composeInternal === 'function';
+  const [directory, setDirectory] = useState<MailPerson[]>([]);
+
+  useEffect(() => {
+    if (!adapter.directory) return;
+    let alive = true;
+    adapter
+      .directory()
+      .then((d) => {
+        if (alive) setDirectory(d);
+      })
+      .catch(() => {
+        if (alive) setDirectory([]);
+      });
+    return () => {
+      alive = false;
+    };
+  }, [adapter]);
+
+  const sendInternal = useCallback(
+    async (recipientUserId: string, subject: string, text: string, attachments?: MailAttachment[]) => {
+      if (!adapter.composeInternal) throw new Error('compose is not supported by this adapter');
+      await adapter.composeInternal(recipientUserId, subject, text, attachments);
+    },
+    [adapter],
+  );
+  const sendExternal = useCallback(
+    async (target: string, subject: string, text: string, attachments?: MailAttachment[]) => {
+      if (!adapter.composeExternal) throw new Error('compose is not supported by this adapter');
+      await adapter.composeExternal(target, subject, text, attachments);
+    },
+    [adapter],
+  );
+  const upload = useCallback(
+    async (file: File) => {
+      if (!adapter.uploadAttachment) throw new Error('attachments are not supported by this adapter');
+      return adapter.uploadAttachment(file);
+    },
+    [adapter],
+  );
+
+  return { supported, directory, sendInternal, sendExternal, canAttach: typeof adapter.uploadAttachment === 'function', upload };
+}
diff --git a/packages/iios-messaging-ui/src/inbox/inbox.test.tsx b/packages/iios-messaging-ui/src/inbox/inbox.test.tsx
new file mode 100644
index 0000000..a9193c7
--- /dev/null
+++ b/packages/iios-messaging-ui/src/inbox/inbox.test.tsx
@@ -0,0 +1,97 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { InboxProvider } from './provider';
+import { Inbox } from './inbox';
+import { MockInboxAdapter } from '../adapters/mock-inbox';
+
+function mount() {
+  return render(
+    <InboxProvider adapter={new MockInboxAdapter()}>
+      <Inbox />
+    </InboxProvider>,
+  );
+}
+
+describe('mock inbox adapter', () => {
+  it('unifies work items + mail in the Open view; other states drop mail', async () => {
+    const a = new MockInboxAdapter();
+    const open = await a.listInbox('OPEN');
+    expect(open.some((i) => i.kind === 'MAIL')).toBe(true);
+    expect(open.some((i) => i.kind === 'MENTION')).toBe(true);
+    const done = await a.listInbox('DONE');
+    expect(done.some((i) => i.kind === 'MAIL')).toBe(false);
+  });
+
+  it('transition moves a work item out of Open', async () => {
+    const a = new MockInboxAdapter();
+    await a.transition('in_3', 'DONE');
+    expect((await a.listInbox('OPEN')).some((i) => i.id === 'in_3')).toBe(false);
+    expect((await a.listInbox('DONE')).some((i) => i.id === 'in_3')).toBe(true);
+  });
+
+  it('mail reply appends to the thread', async () => {
+    const a = new MockInboxAdapter();
+    await a.mailReply('mt_welcome', 'thanks!');
+    expect((await a.mailHistory('mt_welcome')).some((m) => m.text === 'thanks!')).toBe(true);
+  });
+
+  it('reply carries an uploaded attachment', async () => {
+    const a = new MockInboxAdapter();
+    const ref = await a.uploadAttachment(new File(['x'], 'plan.pdf', { type: 'application/pdf' }));
+    expect(ref).toMatchObject({ filename: 'plan.pdf', mimeType: 'application/pdf' });
+    await a.mailReply('mt_welcome', '', ref);
+    const last = (await a.mailHistory('mt_welcome')).at(-1)!;
+    expect(last.attachment?.filename).toBe('plan.pdf');
+  });
+
+  it('composeInternal carries a first attachment onto the new thread', async () => {
+    const a = new MockInboxAdapter();
+    const ref = await a.uploadAttachment(new File(['x'], 'quote.png', { type: 'image/png' }));
+    await a.composeInternal('pp_sofia', 'Quote', 'see attached', [ref]);
+    const open = await a.listInbox('OPEN');
+    const row = open.find((i) => i.title === 'Quote')!;
+    expect((await a.mailHistory(row.threadId!)).at(-1)?.attachment?.filename).toBe('quote.png');
+  });
+});
+
+describe('<Inbox /> (rendered)', () => {
+  it('lists items and opens a mail thread on click', async () => {
+    mount();
+    // A folded mail row is present.
+    const welcome = await screen.findByText('Welcome to the Founders Club');
+    fireEvent.click(welcome);
+    // The reader opens with a reply box.
+    expect(await screen.findByLabelText('Reply')).toBeTruthy();
+  });
+
+  it('replies into a mail thread', async () => {
+    mount();
+    fireEvent.click(await screen.findByText('Welcome to the Founders Club'));
+    const input = (await screen.findByLabelText('Reply')) as HTMLInputElement;
+    fireEvent.change(input, { target: { value: 'got it' } });
+    fireEvent.click(screen.getByText('Reply'));
+    await waitFor(() => expect(screen.getByText('got it')).toBeTruthy());
+  });
+
+  it('attaches a file into a mail reply', async () => {
+    mount();
+    fireEvent.click(await screen.findByText('Welcome to the Founders Club'));
+    const file = new File(['data'], 'roof.pdf', { type: 'application/pdf' });
+    fireEvent.change(await screen.findByLabelText('Attach file'), { target: { files: [file] } });
+    // The pending chip shows the file, then Reply sends it.
+    await screen.findByText(/roof\.pdf/);
+    fireEvent.click(screen.getByText('Reply'));
+    await waitFor(() => expect(screen.getAllByText(/roof\.pdf/).length).toBeGreaterThan(0));
+  });
+
+  it('composes an in-app message and it shows in the inbox', async () => {
+    mount();
+    fireEvent.click(await screen.findByText('New message'));
+    // pick a recipient
+    fireEvent.click(await screen.findByText('Sofia Ramirez'));
+    fireEvent.change(screen.getByLabelText('Subject'), { target: { value: 'Quick q' } });
+    fireEvent.change(screen.getByLabelText('Message body'), { target: { value: 'ping' } });
+    fireEvent.click(screen.getByText('Send'));
+    await waitFor(() => expect(screen.getByText('Quick q')).toBeTruthy());
+  });
+});
diff --git a/packages/iios-messaging-ui/src/inbox/inbox.tsx b/packages/iios-messaging-ui/src/inbox/inbox.tsx
new file mode 100644
index 0000000..4cf235a
--- /dev/null
+++ b/packages/iios-messaging-ui/src/inbox/inbox.tsx
@@ -0,0 +1,328 @@
+import { useEffect, useRef, useState, type FormEvent } from 'react';
+import { ModalPortal } from '../components/modal-portal';
+import { useCompose, useInbox, useMailThread } from './hooks';
+import type { InboxItem, InboxState, MailAttachment, MailPerson } from './types';
+
+const fmtBytes = (n: number): string => {
+  if (!n) return '';
+  if (n < 1024) return `${n} B`;
+  if (n < 1024 * 1024) return `${Math.round(n / 1024)} KB`;
+  return `${(n / (1024 * 1024)).toFixed(1)} MB`;
+};
+
+const FILTERS: { value: InboxState; label: string }[] = [
+  { value: 'OPEN', label: 'Open' },
+  { value: 'SNOOZED', label: 'Snoozed' },
+  { value: 'DONE', label: 'Done' },
+  { value: 'ARCHIVED', label: 'Archived' },
+];
+
+const KIND_LABEL: Record<string, string> = {
+  MAIL: 'Mail',
+  MENTION: 'Mention',
+  NEEDS_REPLY: 'Needs reply',
+  SYSTEM_ALERT: 'Alert',
+  SUPPORT_UPDATE: 'Support',
+};
+
+const timeOf = (iso?: string): string => {
+  if (!iso) return '';
+  const d = new Date(iso);
+  return Number.isNaN(+d) ? '' : d.toLocaleString([], { month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit' });
+};
+
+/** The unified inbox: work items + mail in one list; click a threaded row to read + reply. */
+export function Inbox() {
+  const [filter, setFilter] = useState<InboxState>('OPEN');
+  const { items, loading, error, transition, refetch } = useInbox(filter);
+  const compose = useCompose();
+  const [selectedId, setSelectedId] = useState<string | null>(null);
+  const [composing, setComposing] = useState(false);
+
+  useEffect(() => {
+    if (selectedId && items.some((i) => i.id === selectedId)) return;
+    setSelectedId(items[0]?.id ?? null);
+  }, [items, selectedId]);
+
+  const selected = items.find((i) => i.id === selectedId) ?? null;
+
+  return (
+    <div className="miu-inbox">
+      <div className="miu-inbox-bar">
+        <div className="miu-inbox-filters">
+          {FILTERS.map((f) => (
+            <button key={f.value} type="button" className={`miu-tab${filter === f.value ? ' is-active' : ''}`} onClick={() => setFilter(f.value)}>
+              {f.label}
+            </button>
+          ))}
+        </div>
+        {compose.supported ? (
+          <button type="button" className="miu-send" onClick={() => setComposing(true)}>
+            New message
+          </button>
+        ) : null}
+      </div>
+
+      <div className="miu-inbox-body">
+        <aside className="miu-inbox-list">
+          {loading && items.length === 0 ? <div className="miu-empty">Loading…</div> : null}
+          {error ? <div className="miu-empty miu-error">{error}</div> : null}
+          {!loading && items.length === 0 ? <div className="miu-empty">Nothing here — you&apos;re all caught up 🎉</div> : null}
+          {items.map((it) => (
+            <button key={it.id} type="button" className={`miu-inbox-row${it.id === selectedId ? ' is-active' : ''}`} onClick={() => setSelectedId(it.id)}>
+              <span className="miu-inbox-glyph" aria-hidden="true">{it.kind === 'MAIL' ? '✉' : it.kind === 'MENTION' ? '@' : '•'}</span>
+              <span className="miu-inbox-main">
+                <span className="miu-inbox-row-top">
+                  <span className="miu-pill">{KIND_LABEL[it.kind] ?? it.kind}</span>
+                  <span className="miu-inbox-title">{it.title}</span>
+                </span>
+                {it.summary ? <span className="miu-inbox-summary">{it.summary}</span> : null}
+              </span>
+              {it.state !== 'OPEN' ? <span className="miu-pill">{it.state.toLowerCase()}</span> : null}
+            </button>
+          ))}
+        </aside>
+
+        <section className="miu-inbox-detail">
+          {selected ? <Detail item={selected} onTransition={(s) => void transition(selected.id, s)} /> : <div className="miu-empty miu-thread-empty">Select an item to read.</div>}
+        </section>
+      </div>
+
+      {composing ? <ComposeModal onClose={() => setComposing(false)} onSent={() => { setComposing(false); refetch(); }} /> : null}
+    </div>
+  );
+}
+
+function Detail({ item, onTransition }: { item: InboxItem; onTransition: (state: InboxState) => void }) {
+  return (
+    <div className="miu-detail">
+      {item.state === 'OPEN' && item.kind !== 'MAIL' ? (
+        <div className="miu-detail-actions">
+          <button type="button" className="miu-tab" onClick={() => onTransition('SNOOZED')}>Snooze</button>
+          <button type="button" className="miu-tab" onClick={() => onTransition('DONE')}>Done</button>
+          <button type="button" className="miu-tab" onClick={() => onTransition('ARCHIVED')}>Archive</button>
+        </div>
+      ) : null}
+      {item.threadId ? (
+        <MailReader threadId={item.threadId} subject={item.title} />
+      ) : (
+        <div className="miu-detail-body">
+          <div className="miu-detail-title">{item.title}</div>
+          {item.summary ? <div className="miu-detail-summary">{item.summary}</div> : null}
+        </div>
+      )}
+    </div>
+  );
+}
+
+/** Read a mail thread (HTML in a sandboxed iframe) + reply. */
+export function MailReader({ threadId, subject }: { threadId: string; subject: string }) {
+  const { messages, loading, error, reply, canAttach, upload } = useMailThread(threadId);
+  const [draft, setDraft] = useState('');
+  const [sending, setSending] = useState(false);
+  const [pending, setPending] = useState<MailAttachment | null>(null);
+  const [attaching, setAttaching] = useState(false);
+  const [attachErr, setAttachErr] = useState<string | null>(null);
+  const fileRef = useRef<HTMLInputElement>(null);
+
+  async function pick(e: React.ChangeEvent<HTMLInputElement>): Promise<void> {
+    const file = e.target.files?.[0];
+    e.target.value = '';
+    if (!file) return;
+    setAttaching(true);
+    setAttachErr(null);
+    try {
+      setPending(await upload(file));
+    } catch (err) {
+      setAttachErr(err instanceof Error ? err.message : String(err));
+    } finally {
+      setAttaching(false);
+    }
+  }
+
+  async function submit(e: FormEvent): Promise<void> {
+    e.preventDefault();
+    const text = draft.trim();
+    if ((!text && !pending) || sending) return;
+    const att = pending;
+    setDraft('');
+    setPending(null);
+    setSending(true);
+    try {
+      await reply(text, att ?? undefined);
+    } catch {
+      setDraft(text);
+      setPending(att);
+    } finally {
+      setSending(false);
+    }
+  }
+
+  return (
+    <div className="miu-mail">
+      <header className="miu-mail-head">{subject || '(no subject)'}</header>
+      <div className="miu-mail-body">
+        {loading && messages.length === 0 ? <div className="miu-empty">Loading…</div> : null}
+        {error ? <div className="miu-empty miu-error">{error}</div> : null}
+        {messages.map((m) => (
+          <article key={m.id} className="miu-mail-msg">
+            <div className="miu-mail-meta">
+              <span>{m.kind === 'EMAIL' ? 'Email' : 'Reply'}{m.actorId ? ` · ${m.actorId}` : ''}</span>
+              <span>{timeOf(m.at)}</span>
+            </div>
+            {m.html ? (
+              <iframe sandbox="" srcDoc={m.html} title="mail body" className="miu-mail-frame" />
+            ) : m.text ? (
+              <div className="miu-mail-text">{m.text}</div>
+            ) : null}
+            {m.attachment ? (
+              <span className="miu-attach-chip">📎 {m.attachment.filename ?? 'attachment'}{m.attachment.sizeBytes ? ` · ${fmtBytes(m.attachment.sizeBytes)}` : ''}</span>
+            ) : null}
+          </article>
+        ))}
+      </div>
+      <form className="miu-composer" onSubmit={submit}>
+        {attachErr ? <div className="miu-empty miu-error">{attachErr}</div> : null}
+        {pending ? (
+          <div className="miu-attach-pending">
+            <span className="miu-attach-chip">📎 {pending.filename ?? 'attachment'}{pending.sizeBytes ? ` · ${fmtBytes(pending.sizeBytes)}` : ''}</span>
+            <button type="button" className="miu-attach-x" onClick={() => setPending(null)} aria-label="Remove attachment">✕</button>
+          </div>
+        ) : null}
+        <div className="miu-composer-row">
+          {canAttach ? (
+            <>
+              <input ref={fileRef} type="file" hidden onChange={pick} aria-label="Attach file" />
+              <button type="button" className="miu-attach-btn" onClick={() => fileRef.current?.click()} disabled={attaching || !!pending} title="Attach a file" aria-label="Attach a file">
+                {attaching ? '…' : '📎'}
+              </button>
+            </>
+          ) : null}
+          <input className="miu-input" value={draft} onChange={(e) => setDraft(e.target.value)} placeholder="Reply…" aria-label="Reply" />
+          <button type="submit" className="miu-send" disabled={(!draft.trim() && !pending) || sending}>Reply</button>
+        </div>
+      </form>
+    </div>
+  );
+}
+
+function ComposeModal({ onClose, onSent }: { onClose: () => void; onSent: () => void }) {
+  const compose = useCompose();
+  const [mode, setMode] = useState<'internal' | 'external'>('internal');
+  const [recipient, setRecipient] = useState('');
+  const [subject, setSubject] = useState('');
+  const [body, setBody] = useState('');
+  const [q, setQ] = useState('');
+  const [busy, setBusy] = useState(false);
+  const [err, setErr] = useState<string | null>(null);
+  const [attachments, setAttachments] = useState<MailAttachment[]>([]);
+  const [attaching, setAttaching] = useState(false);
+  const fileRef = useRef<HTMLInputElement>(null);
+
+  const filtered = compose.directory.filter((p) => p.name.toLowerCase().includes(q.trim().toLowerCase()));
+  const canSend = !!recipient && !!subject.trim() && (!!body.trim() || attachments.length > 0) && !busy && !attaching;
+
+  async function pick(e: React.ChangeEvent<HTMLInputElement>): Promise<void> {
+    const file = e.target.files?.[0];
+    e.target.value = '';
+    if (!file || attachments.length >= 10) return;
+    setAttaching(true);
+    setErr(null);
+    try {
+      const ref = await compose.upload(file);
+      setAttachments((a) => [...a, ref]);
+    } catch (e2) {
+      setErr(e2 instanceof Error ? e2.message : String(e2));
+    } finally {
+      setAttaching(false);
+    }
+  }
+
+  async function send(): Promise<void> {
+    if (!canSend) return;
+    setBusy(true);
+    setErr(null);
+    const atts = attachments.length > 0 ? attachments : undefined;
+    try {
+      if (mode === 'internal') await compose.sendInternal(recipient, subject.trim(), body.trim(), atts);
+      else await compose.sendExternal(recipient.trim(), subject.trim(), body.trim(), atts);
+      onSent();
+    } catch (e) {
+      setErr(e instanceof Error ? e.message : String(e));
+    } finally {
+      setBusy(false);
+    }
+  }
+
+  return (
+    <ModalPortal>
+      <div className="miu-modal-overlay" onMouseDown={onClose}>
+      <div className="miu-modal" role="dialog" aria-modal="true" onMouseDown={(e) => e.stopPropagation()}>
+        <div className="miu-modal-head">
+          <span>New message</span>
+          <button type="button" className="miu-pane-close" onClick={onClose} aria-label="Close">✕</button>
+        </div>
+        <div className="miu-modal-body">
+          <div className="miu-compose-modes">
+            <button type="button" className={`miu-tab${mode === 'internal' ? ' is-active' : ''}`} onClick={() => { setMode('internal'); setRecipient(''); }}>In-app</button>
+            <button type="button" className={`miu-tab${mode === 'external' ? ' is-active' : ''}`} onClick={() => { setMode('external'); setRecipient(''); }}>Email</button>
+          </div>
+
+          {mode === 'internal' ? (
+            <div className="miu-field">
+              <span className="miu-field-lbl">To (person)</span>
+              <input className="miu-input" value={q} onChange={(e) => setQ(e.target.value)} placeholder="Search people…" aria-label="Search people" />
+              <div className="miu-people">
+                {filtered.length === 0 ? <div className="miu-empty">No people found.</div> : null}
+                {filtered.map((p: MailPerson) => (
+                  <label key={p.id} className={`miu-person${recipient === p.id ? ' is-active' : ''}`}>
+                    <input type="radio" name="miu-recipient" checked={recipient === p.id} onChange={() => setRecipient(p.id)} />
+                    <span>{p.name}</span>
+                    <span className="miu-pill">{p.kind}</span>
+                  </label>
+                ))}
+              </div>
+            </div>
+          ) : (
+            <div className="miu-field">
+              <span className="miu-field-lbl">To (email)</span>
+              <input className="miu-input" value={recipient} onChange={(e) => setRecipient(e.target.value)} placeholder="name@company.com" aria-label="To email" />
+            </div>
+          )}
+
+          <div className="miu-field">
+            <span className="miu-field-lbl">Subject</span>
+            <input className="miu-input" value={subject} onChange={(e) => setSubject(e.target.value)} placeholder="Subject" aria-label="Subject" />
+          </div>
+          <div className="miu-field">
+            <span className="miu-field-lbl">Message</span>
+            <textarea className="miu-input miu-textarea" value={body} onChange={(e) => setBody(e.target.value)} placeholder="Write your message…" rows={5} aria-label="Message body" />
+          </div>
+          {compose.canAttach ? (
+            <div className="miu-field">
+              <span className="miu-field-lbl">Attachments</span>
+              <div className="miu-attach-list">
+                {attachments.map((a, i) => (
+                  <span key={`${a.contentRef}-${i}`} className="miu-attach-pending">
+                    <span className="miu-attach-chip">📎 {a.filename ?? 'attachment'}{a.sizeBytes ? ` · ${fmtBytes(a.sizeBytes)}` : ''}</span>
+                    <button type="button" className="miu-attach-x" onClick={() => setAttachments((prev) => prev.filter((_, j) => j !== i))} aria-label="Remove attachment">✕</button>
+                  </span>
+                ))}
+                <input ref={fileRef} type="file" hidden onChange={pick} aria-label="Attach file" />
+                <button type="button" className="miu-tab" onClick={() => fileRef.current?.click()} disabled={attaching || attachments.length >= 10}>
+                  {attaching ? 'Uploading…' : '📎 Attach'}
+                </button>
+              </div>
+            </div>
+          ) : null}
+          {err ? <div className="miu-empty miu-error">{err}</div> : null}
+        </div>
+        <div className="miu-modal-foot">
+          <button type="button" className="miu-tab" onClick={onClose}>Cancel</button>
+          <button type="button" className="miu-send" onClick={() => void send()} disabled={!canSend}>{busy ? 'Sending…' : 'Send'}</button>
+        </div>
+      </div>
+      </div>
+    </ModalPortal>
+  );
+}
diff --git a/packages/iios-messaging-ui/src/inbox/provider.tsx b/packages/iios-messaging-ui/src/inbox/provider.tsx
new file mode 100644
index 0000000..699d45b
--- /dev/null
+++ b/packages/iios-messaging-ui/src/inbox/provider.tsx
@@ -0,0 +1,16 @@
+import { createContext, useContext, type ReactNode } from 'react';
+import type { InboxAdapter } from './adapter';
+
+const InboxContext = createContext<InboxAdapter | null>(null);
+
+export function InboxProvider({ adapter, children }: { adapter: InboxAdapter; children: ReactNode }) {
+  return <InboxContext.Provider value={adapter}>{children}</InboxContext.Provider>;
+}
+
+/** Access the host-injected inbox adapter. Throws outside a provider — a missing provider is a
+ *  wiring bug, and failing loudly beats a confusing null-deref three layers down. */
+export function useInboxAdapter(): InboxAdapter {
+  const adapter = useContext(InboxContext);
+  if (!adapter) throw new Error('useInboxAdapter must be used within an <InboxProvider>');
+  return adapter;
+}
diff --git a/packages/iios-messaging-ui/src/inbox/types.ts b/packages/iios-messaging-ui/src/inbox/types.ts
new file mode 100644
index 0000000..bcc4fc7
--- /dev/null
+++ b/packages/iios-messaging-ui/src/inbox/types.ts
@@ -0,0 +1,42 @@
+// Domain types for the inbox surface (work items + mail). Zero transport imports.
+
+export type InboxState = 'OPEN' | 'SNOOZED' | 'DONE' | 'ARCHIVED' | 'CANCELLED' | 'STALE';
+
+/** A unified inbox row — a work item (mention/needs-reply/alert) OR a mail thread. */
+export interface InboxItem {
+  id: string;
+  kind: string; // MAIL | MENTION | NEEDS_REPLY | SYSTEM_ALERT | …
+  state: InboxState;
+  title: string;
+  summary?: string;
+  priority: string;
+  /** Present when the row opens a conversation/mail thread. */
+  threadId?: string;
+  createdAt: string;
+}
+
+/** A mail attachment reference (bytes live in storage; the reader resolves a display URL). */
+export interface MailAttachment {
+  contentRef: string;
+  mimeType: string;
+  sizeBytes: number;
+  filename: string | null;
+}
+
+/** One message in a mail thread — HTML and/or plain text, optionally an attachment. */
+export interface MailMessage {
+  id: string;
+  actorId: string | null;
+  kind: string;
+  at: string;
+  html: string | null;
+  text: string | null;
+  attachment: MailAttachment | null;
+}
+
+/** A person you can compose an in-app message to. */
+export interface MailPerson {
+  id: string;
+  name: string;
+  kind: 'staff' | 'customer';
+}
diff --git a/packages/iios-messaging-ui/src/index.ts b/packages/iios-messaging-ui/src/index.ts
new file mode 100644
index 0000000..be6f1b6
--- /dev/null
+++ b/packages/iios-messaging-ui/src/index.ts
@@ -0,0 +1,44 @@
+// Public API. Components land in Plan 2; adapters/kernel in Plan 3.
+//
+// `runAdapterConformance` is deliberately NOT exported here — it imports vitest and
+// ships from the './conformance' subpath so consumers never pull a test runner into
+// their production bundle.
+export { MessagingProvider, useAdapter } from './provider';
+export { useConversations } from './hooks/use-conversations';
+export { useMessages } from './hooks/use-messages';
+export { useChannels } from './hooks/use-channels';
+export { useMembers } from './hooks/use-members';
+export { isOwnMessage } from './types';
+
+// Rendered UI. Pair with the './styles.css' export (or override the --miu-* tokens).
+export { Messenger } from './components/messenger';
+export { ConversationList } from './components/conversation-list';
+export { ChannelBrowser } from './components/channel-browser';
+export { Thread } from './components/thread';
+export { ThreadPane } from './components/thread-pane';
+
+// ── Inbox domain (work items + mail) ──
+export { InboxProvider, useInboxAdapter } from './inbox/provider';
+export { useInbox, useMailThread, useCompose } from './inbox/hooks';
+export { Inbox, MailReader } from './inbox/inbox';
+export type { InboxAdapter } from './inbox/adapter';
+export type { InboxItem, InboxState, MailAttachment, MailMessage, MailPerson } from './inbox/types';
+
+export type { MessagingAdapter } from './adapter';
+export type { ConversationsState } from './hooks/use-conversations';
+export type { MessagesState, UiMessage } from './hooks/use-messages';
+export type { ChannelsState } from './hooks/use-channels';
+export type {
+  Attachment,
+  ChannelSummary,
+  ChannelVisibility,
+  Conversation,
+  CreateChannelInput,
+  Membership,
+  Message,
+  MessageEvent,
+  Person,
+  Reaction,
+  SendOpts,
+  Unsubscribe,
+} from './types';
diff --git a/packages/iios-messaging-ui/src/mentions.test.tsx b/packages/iios-messaging-ui/src/mentions.test.tsx
new file mode 100644
index 0000000..4cc6ae6
--- /dev/null
+++ b/packages/iios-messaging-ui/src/mentions.test.tsx
@@ -0,0 +1,55 @@
+import { describe, it, expect, vi } from 'vitest';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { MessagingProvider } from './provider';
+import { Messenger } from './components/messenger';
+import { MockAdapter } from './adapters/mock';
+import { insertMention, resolveMentions, trailingMentionQuery } from './mentions';
+import type { Person } from './types';
+
+const people: Person[] = [
+  { id: 'pp_sofia', name: 'Sofia Ramirez', kind: 'staff' },
+  { id: 'pp_dan', name: 'Dan Whitaker', kind: 'staff' },
+];
+
+describe('mention helpers', () => {
+  it('trailingMentionQuery finds the @token being typed', () => {
+    expect(trailingMentionQuery('hey @Sof')).toBe('Sof');
+    expect(trailingMentionQuery('@')).toBe('');
+    expect(trailingMentionQuery('no mention here')).toBeNull();
+    expect(trailingMentionQuery('done @Sofia Ramirez ')).toBeNull(); // completed, trailing space
+  });
+
+  it('insertMention replaces the trailing query, keeping the boundary', () => {
+    expect(insertMention('hey @Sof', 'Sofia Ramirez')).toBe('hey @Sofia Ramirez ');
+    expect(insertMention('@ch', 'channel')).toBe('@channel ');
+  });
+
+  it('resolveMentions maps names to ids; @channel expands to everyone', () => {
+    expect(resolveMentions('ping @Sofia Ramirez', people)).toEqual(['pp_sofia']);
+    expect(resolveMentions('nobody here', people)).toEqual([]);
+    expect(resolveMentions('@channel ship it', people).sort()).toEqual(['pp_dan', 'pp_sofia']);
+  });
+});
+
+describe('<Thread /> @mention autocomplete', () => {
+  it('picking a suggestion inserts the name and send carries the mention id', async () => {
+    const adapter = new MockAdapter();
+    const sendSpy = vi.spyOn(adapter, 'send');
+    render(
+      <MessagingProvider adapter={adapter}>
+        <Messenger />
+      </MessagingProvider>,
+    );
+    const input = (await screen.findByLabelText('Message')) as HTMLInputElement;
+    fireEvent.change(input, { target: { value: 'hey @Sof' } });
+
+    // The suggestion (role=option) is distinct from the sidebar row of the same name.
+    fireEvent.click(await screen.findByRole('option', { name: 'Sofia Ramirez' }));
+    expect(input.value).toBe('hey @Sofia Ramirez ');
+
+    fireEvent.click(screen.getByText('Send'));
+    await waitFor(() => expect(sendSpy).toHaveBeenCalled());
+    const opts = sendSpy.mock.calls[0]![2];
+    expect(opts?.mentions).toContain('pp_sofia');
+  });
+});
diff --git a/packages/iios-messaging-ui/src/mentions.tsx b/packages/iios-messaging-ui/src/mentions.tsx
new file mode 100644
index 0000000..4533c8a
--- /dev/null
+++ b/packages/iios-messaging-ui/src/mentions.tsx
@@ -0,0 +1,51 @@
+import type { ReactNode } from 'react';
+import type { Person } from './types';
+
+/** Room-wide mention tokens, always offered alongside members. */
+export const SPECIAL_MENTIONS = ['channel', 'here'];
+
+function esc(s: string): string {
+  return s.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
+}
+
+/** The @token currently being typed at the end of the draft (caret-at-end), or null. */
+export function trailingMentionQuery(draft: string): string | null {
+  const m = draft.match(/(?:^|\s)@([\w]*)$/);
+  return m ? (m[1] ?? '') : null;
+}
+
+/** Replace the trailing @query with `@insert ` (keeping the leading boundary). */
+export function insertMention(draft: string, insert: string): string {
+  return draft.replace(/(^|\s)@([\w]*)$/, (_full, lead: string) => `${lead}@${insert} `);
+}
+
+/** Resolve the opaque mention userId list from the final text + known members. */
+export function resolveMentions(text: string, members: Person[]): string[] {
+  const ids = new Set<string>();
+  for (const p of members) if (text.includes(`@${p.name}`)) ids.add(p.id);
+  if (/@channel\b/.test(text) || /@here\b/.test(text)) for (const p of members) ids.add(p.id);
+  return [...ids];
+}
+
+/** Render text with @mentions (member names + @channel/@here) wrapped for highlighting. */
+export function highlightMentions(text: string, memberNames: string[]): ReactNode[] {
+  // Longest-first so "@Sofia Ramirez" wins over a bare "@Sofia".
+  const names = [...new Set([...memberNames, ...SPECIAL_MENTIONS])].filter(Boolean).sort((a, b) => b.length - a.length);
+  if (names.length === 0) return [text];
+  const re = new RegExp(`@(${names.map(esc).join('|')})`, 'g');
+  const out: ReactNode[] = [];
+  let last = 0;
+  let key = 0;
+  let m: RegExpExecArray | null;
+  while ((m = re.exec(text)) !== null) {
+    if (m.index > last) out.push(text.slice(last, m.index));
+    out.push(
+      <span key={`m${key++}`} className="miu-mention">
+        {m[0]}
+      </span>,
+    );
+    last = m.index + m[0].length;
+  }
+  if (last < text.length) out.push(text.slice(last));
+  return out.length > 0 ? out : [text];
+}
diff --git a/packages/iios-messaging-ui/src/provider.test.tsx b/packages/iios-messaging-ui/src/provider.test.tsx
new file mode 100644
index 0000000..7054c46
--- /dev/null
+++ b/packages/iios-messaging-ui/src/provider.test.tsx
@@ -0,0 +1,25 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import { MessagingProvider, useAdapter } from './provider';
+import { MockAdapter } from './adapters/mock';
+
+function ShowActor() {
+  const adapter = useAdapter();
+  return <span>{adapter.currentActorId()}</span>;
+}
+
+describe('MessagingProvider', () => {
+  it('supplies the injected adapter to descendants', () => {
+    render(
+      <MessagingProvider adapter={new MockAdapter()}>
+        <ShowActor />
+      </MessagingProvider>,
+    );
+    expect(screen.getByText('me')).toBeDefined();
+  });
+
+  it('throws a helpful error when a hook is used outside the provider', () => {
+    // React logs the error boundary trace; that noise is expected.
+    expect(() => render(<ShowActor />)).toThrow(/useAdapter must be used within a <MessagingProvider>/);
+  });
+});
diff --git a/packages/iios-messaging-ui/src/provider.tsx b/packages/iios-messaging-ui/src/provider.tsx
new file mode 100644
index 0000000..748c00f
--- /dev/null
+++ b/packages/iios-messaging-ui/src/provider.tsx
@@ -0,0 +1,22 @@
+import { createContext, useContext, type ReactNode } from 'react';
+import type { MessagingAdapter } from './adapter';
+
+const AdapterContext = createContext<MessagingAdapter | null>(null);
+
+export function MessagingProvider({
+  adapter,
+  children,
+}: {
+  adapter: MessagingAdapter;
+  children: ReactNode;
+}) {
+  return <AdapterContext.Provider value={adapter}>{children}</AdapterContext.Provider>;
+}
+
+/** Access the host-injected adapter. Throws outside a provider — a missing provider is
+ *  a wiring bug, and failing loudly beats a confusing null-deref three layers down. */
+export function useAdapter(): MessagingAdapter {
+  const adapter = useContext(AdapterContext);
+  if (!adapter) throw new Error('useAdapter must be used within a <MessagingProvider>');
+  return adapter;
+}
diff --git a/packages/iios-messaging-ui/src/smoke.test.tsx b/packages/iios-messaging-ui/src/smoke.test.tsx
new file mode 100644
index 0000000..3af897f
--- /dev/null
+++ b/packages/iios-messaging-ui/src/smoke.test.tsx
@@ -0,0 +1,9 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen } from '@testing-library/react';
+
+describe('test infrastructure', () => {
+  it('renders React components in jsdom', () => {
+    render(<div>messaging-ui</div>);
+    expect(screen.getByText('messaging-ui')).toBeDefined();
+  });
+});
diff --git a/packages/iios-messaging-ui/src/styles.css b/packages/iios-messaging-ui/src/styles.css
new file mode 100644
index 0000000..c7b01c2
--- /dev/null
+++ b/packages/iios-messaging-ui/src/styles.css
@@ -0,0 +1,944 @@
+/* Default theme for @insignia/iios-messaging-ui. Everything is driven by CSS variables
+   scoped to .miu-messenger, so a host restyles by overriding the tokens — no component edits. */
+.miu-messenger {
+  --miu-bg: #0e0e13;
+  --miu-panel: #16161d;
+  --miu-panel-2: #1d1d26;
+  --miu-border: #262631;
+  --miu-text: #e9e9ef;
+  --miu-muted: #9a9aa7;
+  --miu-accent: #fda913;
+  --miu-accent-text: #1a1206;
+  --miu-radius: 12px;
+
+  display: flex;
+  height: 100%;
+  min-height: 0;
+  color: var(--miu-text);
+  background: var(--miu-bg);
+  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
+  font-size: 14px;
+}
+
+.miu-sidebar {
+  width: 300px;
+  flex-shrink: 0;
+  border-right: 1px solid var(--miu-border);
+  overflow-y: auto;
+  background: var(--miu-panel);
+}
+
+.miu-main {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+}
+
+/* conversation list */
+.miu-convlist {
+  list-style: none;
+  margin: 0;
+  padding: 0;
+}
+.miu-convrow {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  width: 100%;
+  padding: 11px 14px;
+  border: none;
+  border-bottom: 1px solid var(--miu-border);
+  background: transparent;
+  color: inherit;
+  text-align: left;
+  cursor: pointer;
+  font: inherit;
+}
+.miu-convrow:hover {
+  background: var(--miu-panel-2);
+}
+.miu-convrow.is-active {
+  background: var(--miu-panel-2);
+}
+.miu-avatar {
+  width: 34px;
+  height: 34px;
+  flex-shrink: 0;
+  border-radius: 50%;
+  display: grid;
+  place-items: center;
+  font-size: 12px;
+  font-weight: 700;
+  color: var(--miu-accent-text);
+  background: var(--miu-accent);
+}
+.miu-convrow-main {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+}
+.miu-convrow-title {
+  font-weight: 600;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+.miu-convrow-preview {
+  color: var(--miu-muted);
+  font-size: 12.5px;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+.miu-badge {
+  flex-shrink: 0;
+  min-width: 18px;
+  height: 18px;
+  padding: 0 5px;
+  border-radius: 999px;
+  display: grid;
+  place-items: center;
+  font-size: 11px;
+  font-weight: 700;
+  color: var(--miu-accent-text);
+  background: var(--miu-accent);
+}
+
+/* thread */
+.miu-thread {
+  display: flex;
+  flex-direction: column;
+  height: 100%;
+  min-height: 0;
+}
+.miu-messages {
+  flex: 1;
+  min-height: 0;
+  overflow-y: auto;
+  padding: 16px;
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+}
+.miu-msg {
+  display: flex;
+  flex-direction: column;
+  align-items: flex-start;
+  max-width: 78%;
+}
+.miu-msg.is-mine {
+  align-self: flex-end;
+  align-items: flex-end;
+}
+.miu-bubble {
+  padding: 8px 12px;
+  border-radius: 14px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+  white-space: pre-wrap;
+  word-break: break-word;
+}
+.miu-msg.is-mine .miu-bubble {
+  border: none;
+  color: var(--miu-accent-text);
+  background: var(--miu-accent);
+}
+.miu-msg.is-pending {
+  opacity: 0.6;
+}
+.miu-bubble-row {
+  display: flex;
+  align-items: center;
+  gap: 4px;
+}
+.miu-msg.is-mine .miu-bubble-row {
+  flex-direction: row-reverse;
+}
+.miu-msg-actions {
+  display: flex;
+  gap: 2px;
+  flex-shrink: 0;
+}
+.miu-thread-link {
+  align-self: flex-start;
+  margin-top: 3px;
+  padding: 3px 9px;
+  border-radius: 999px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+  color: var(--miu-accent);
+  font-size: 12px;
+  font-weight: 600;
+  cursor: pointer;
+}
+.miu-msg.is-mine .miu-thread-link {
+  align-self: flex-end;
+}
+.miu-react-wrap {
+  position: relative;
+  flex-shrink: 0;
+}
+.miu-react-btn {
+  border: none;
+  background: none;
+  cursor: pointer;
+  opacity: 0;
+  font-size: 14px;
+  padding: 2px;
+  transition: opacity 0.12s;
+}
+.miu-msg:hover .miu-react-btn {
+  opacity: 0.6;
+}
+.miu-react-btn:hover {
+  opacity: 1;
+}
+.miu-react-picker {
+  position: absolute;
+  /* Open downward + right-aligned so it never clips against the top of the scroll area
+     (the reported bug) or spills past the right edge. */
+  top: 100%;
+  right: 0;
+  margin-top: 4px;
+  display: flex;
+  gap: 2px;
+  padding: 4px;
+  border-radius: 999px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.4);
+  z-index: 5;
+  width: max-content;
+}
+/* On my own (right-aligned) messages, anchor the picker to the left instead so it stays in view. */
+.miu-msg.is-mine .miu-react-picker {
+  right: auto;
+  left: 0;
+}
+.miu-react-emoji {
+  border: none;
+  background: none;
+  cursor: pointer;
+  font-size: 16px;
+  padding: 2px 4px;
+  border-radius: 6px;
+}
+.miu-react-emoji:hover {
+  background: var(--miu-panel-2);
+}
+.miu-reactions {
+  display: flex;
+  gap: 4px;
+  margin-top: 3px;
+}
+.miu-reaction {
+  font-size: 12px;
+  padding: 1px 7px;
+  border-radius: 999px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel-2);
+  color: var(--miu-text);
+  cursor: pointer;
+}
+.miu-reaction.is-mine {
+  border-color: var(--miu-accent);
+}
+
+/* attachments */
+.miu-att-img-link {
+  display: inline-block;
+  margin-top: 4px;
+}
+.miu-att-img {
+  max-width: 260px;
+  max-height: 220px;
+  border-radius: 8px;
+  border: 1px solid var(--miu-border);
+}
+.miu-att-file {
+  display: inline-block;
+  margin-top: 4px;
+  padding: 6px 10px;
+  border-radius: 8px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel-2);
+  color: var(--miu-text);
+  text-decoration: none;
+  font-size: 13px;
+}
+.miu-seen {
+  font-size: 11px;
+  color: var(--miu-muted);
+  margin-top: 2px;
+}
+.miu-typing {
+  font-size: 12.5px;
+  color: var(--miu-muted);
+  font-style: italic;
+}
+
+/* mentions */
+.miu-mention {
+  color: var(--miu-accent);
+  font-weight: 600;
+}
+.miu-msg.is-mine .miu-bubble .miu-mention {
+  color: var(--miu-accent-text);
+  text-decoration: underline;
+}
+
+/* composer */
+.miu-composer {
+  position: relative;
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  padding: 12px;
+  border-top: 1px solid var(--miu-border);
+}
+.miu-composer-row {
+  display: flex;
+  gap: 8px;
+}
+.miu-file-input {
+  display: none;
+}
+.miu-attach-btn {
+  flex-shrink: 0;
+  width: 38px;
+  border-radius: 10px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+  color: var(--miu-text);
+  cursor: pointer;
+  font-size: 16px;
+}
+.miu-staged {
+  display: inline-flex;
+  align-items: center;
+  gap: 8px;
+  align-self: flex-start;
+  padding: 5px 10px;
+  border-radius: 999px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel-2);
+  font-size: 13px;
+}
+.miu-staged-x {
+  border: none;
+  background: none;
+  color: var(--miu-muted);
+  cursor: pointer;
+  padding: 0;
+  line-height: 1;
+}
+
+/* inbox mail attachments */
+.miu-attach-chip {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  padding: 4px 10px;
+  border-radius: 999px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel-2);
+  color: var(--miu-text);
+  font-size: 12.5px;
+  max-width: 100%;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.miu-mail-msg .miu-attach-chip {
+  margin-top: 6px;
+}
+.miu-attach-pending {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+}
+.miu-attach-x {
+  border: none;
+  background: none;
+  color: var(--miu-muted);
+  cursor: pointer;
+  padding: 0 2px;
+  line-height: 1;
+  font-size: 12px;
+}
+.miu-attach-list {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  gap: 8px;
+}
+.miu-suggest {
+  position: absolute;
+  left: 12px;
+  right: 12px;
+  bottom: calc(100% - 4px);
+  margin: 0;
+  padding: 4px;
+  list-style: none;
+  max-height: 200px;
+  overflow-y: auto;
+  border: 1px solid var(--miu-border);
+  border-radius: var(--miu-radius);
+  background: var(--miu-panel);
+  box-shadow: 0 10px 30px -12px rgba(0, 0, 0, 0.6);
+  z-index: 5;
+}
+.miu-suggest-item {
+  display: block;
+  width: 100%;
+  text-align: left;
+  padding: 7px 10px;
+  border: none;
+  border-radius: 8px;
+  background: transparent;
+  color: var(--miu-text);
+  font: inherit;
+  cursor: pointer;
+}
+.miu-suggest-item:hover {
+  background: var(--miu-panel-2);
+}
+.miu-input {
+  flex: 1;
+  padding: 9px 12px;
+  border-radius: 10px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+  color: var(--miu-text);
+  font: inherit;
+  outline: none;
+}
+.miu-input:focus {
+  border-color: var(--miu-accent);
+}
+.miu-send {
+  padding: 0 16px;
+  border-radius: 10px;
+  border: none;
+  font-weight: 700;
+  cursor: pointer;
+  color: var(--miu-accent-text);
+  background: var(--miu-accent);
+}
+.miu-send:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+/* sidebar sections + channel browser */
+.miu-section {
+  border-bottom: 1px solid var(--miu-border);
+}
+.miu-section-head {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 10px 14px 4px;
+  font-size: 11px;
+  font-weight: 700;
+  letter-spacing: 0.06em;
+  text-transform: uppercase;
+  color: var(--miu-muted);
+}
+.miu-section-add {
+  border: none;
+  background: transparent;
+  color: var(--miu-muted);
+  cursor: pointer;
+  font-size: 16px;
+  line-height: 1;
+  padding: 0 4px;
+}
+.miu-section-add:hover {
+  color: var(--miu-text);
+}
+.miu-empty-sm {
+  padding: 8px 14px 12px;
+  text-align: left;
+  font-size: 12.5px;
+}
+
+.miu-browser {
+  display: flex;
+  flex-direction: column;
+  height: 100%;
+  min-height: 0;
+  padding: 16px;
+  gap: 14px;
+  overflow-y: auto;
+}
+.miu-browser-head {
+  font-size: 16px;
+  font-weight: 700;
+}
+.miu-channel-create {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  padding: 12px;
+  border: 1px solid var(--miu-border);
+  border-radius: var(--miu-radius);
+  background: var(--miu-panel);
+}
+.miu-channel-vis {
+  display: flex;
+  gap: 16px;
+  font-size: 13px;
+  color: var(--miu-muted);
+}
+.miu-channel-vis label {
+  display: inline-flex;
+  align-items: center;
+  gap: 5px;
+  cursor: pointer;
+}
+/* new conversation (DM / group) picker */
+.miu-newconv {
+  display: flex;
+  flex-direction: column;
+  gap: 10px;
+}
+/* Submit buttons in the stacked create/compose forms size to content, not full width. */
+.miu-newconv .miu-send,
+.miu-channel-create .miu-send {
+  align-self: flex-start;
+  height: 38px;
+}
+.miu-person-row {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  padding: 8px 10px;
+  border: 1px solid var(--miu-border);
+  border-radius: 10px;
+  background: var(--miu-panel);
+  cursor: pointer;
+}
+.miu-person-row:hover {
+  border-color: var(--miu-accent);
+}
+.miu-person-row.is-active {
+  border-color: var(--miu-accent);
+  background: color-mix(in srgb, var(--miu-accent) 10%, var(--miu-panel));
+}
+.miu-person-row .miu-browser-name {
+  flex: 1 1 auto;
+}
+.miu-browser-list {
+  display: flex;
+  flex-direction: column;
+  gap: 6px;
+}
+.miu-browser-row {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  padding: 10px 12px;
+  border: 1px solid var(--miu-border);
+  border-radius: var(--miu-radius);
+  background: var(--miu-panel);
+}
+.miu-channel-glyph {
+  width: 30px;
+  height: 30px;
+  flex-shrink: 0;
+  border-radius: 8px;
+  display: grid;
+  place-items: center;
+  font-weight: 700;
+  color: var(--miu-muted);
+  background: var(--miu-panel-2);
+}
+.miu-browser-main {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+  gap: 1px;
+}
+.miu-browser-name {
+  font-weight: 600;
+}
+.miu-browser-topic {
+  font-size: 12.5px;
+  color: var(--miu-muted);
+}
+.miu-browser-meta {
+  font-size: 11.5px;
+  color: var(--miu-muted);
+}
+.miu-join {
+  flex-shrink: 0;
+  padding: 5px 14px;
+  border-radius: 8px;
+  border: none;
+  font-weight: 700;
+  cursor: pointer;
+  color: var(--miu-accent-text);
+  background: var(--miu-accent);
+}
+.miu-browser-joined {
+  flex-shrink: 0;
+  font-size: 12px;
+  color: var(--miu-muted);
+}
+
+/* thread pane (Slack-style) */
+.miu-pane {
+  width: 340px;
+  flex-shrink: 0;
+  display: flex;
+  flex-direction: column;
+  min-height: 0;
+  border-left: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+}
+.miu-pane-head {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 12px 16px;
+  border-bottom: 1px solid var(--miu-border);
+  font-weight: 700;
+}
+.miu-pane-close {
+  border: none;
+  background: none;
+  color: var(--miu-muted);
+  cursor: pointer;
+  font-size: 15px;
+}
+.miu-pane-messages {
+  background: var(--miu-bg);
+}
+.miu-pane-divider {
+  font-size: 11.5px;
+  color: var(--miu-muted);
+  text-align: center;
+  margin: 4px 0;
+  padding-bottom: 4px;
+  border-bottom: 1px solid var(--miu-border);
+}
+
+/* ── Inbox ── */
+.miu-inbox {
+  --miu-bg: #0e0e13;
+  --miu-panel: #16161d;
+  --miu-panel-2: #1d1d26;
+  --miu-border: #262631;
+  --miu-text: #e9e9ef;
+  --miu-muted: #9a9aa7;
+  --miu-accent: #fda913;
+  --miu-accent-text: #1a1206;
+  --miu-radius: 12px;
+
+  display: flex;
+  flex-direction: column;
+  height: 100%;
+  min-height: 0;
+  color: var(--miu-text);
+  background: var(--miu-bg);
+  font-family: system-ui, -apple-system, 'Segoe UI', sans-serif;
+  font-size: 14px;
+}
+.miu-inbox-bar {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 8px;
+  padding: 10px 12px;
+  border-bottom: 1px solid var(--miu-border);
+}
+.miu-inbox-filters {
+  display: flex;
+  gap: 4px;
+}
+.miu-tab {
+  padding: 6px 12px;
+  border-radius: 999px;
+  border: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+  color: var(--miu-text);
+  font: inherit;
+  font-size: 13px;
+  cursor: pointer;
+}
+.miu-tab.is-active {
+  background: var(--miu-accent);
+  color: var(--miu-accent-text);
+  border-color: var(--miu-accent);
+  font-weight: 700;
+}
+.miu-inbox-body {
+  flex: 1;
+  min-height: 0;
+  display: flex;
+}
+.miu-inbox-list {
+  width: 340px;
+  flex-shrink: 0;
+  overflow-y: auto;
+  border-right: 1px solid var(--miu-border);
+  background: var(--miu-panel);
+}
+.miu-inbox-row {
+  display: flex;
+  align-items: flex-start;
+  gap: 10px;
+  width: 100%;
+  padding: 12px 14px;
+  border: none;
+  border-bottom: 1px solid var(--miu-border);
+  background: transparent;
+  color: inherit;
+  text-align: left;
+  cursor: pointer;
+  font: inherit;
+}
+.miu-inbox-row:hover,
+.miu-inbox-row.is-active {
+  background: var(--miu-panel-2);
+}
+.miu-inbox-glyph {
+  width: 26px;
+  height: 26px;
+  flex-shrink: 0;
+  border-radius: 7px;
+  display: grid;
+  place-items: center;
+  color: var(--miu-muted);
+  background: var(--miu-panel-2);
+  font-weight: 700;
+}
+.miu-inbox-main {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+}
+.miu-inbox-row-top {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+}
+.miu-pill {
+  flex-shrink: 0;
+  font-size: 10.5px;
+  font-weight: 700;
+  padding: 1px 7px;
+  border-radius: 999px;
+  color: var(--miu-muted);
+  background: var(--miu-panel-2);
+  text-transform: capitalize;
+}
+.miu-inbox-title {
+  font-weight: 600;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+.miu-inbox-summary {
+  color: var(--miu-muted);
+  font-size: 12.5px;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+.miu-inbox-detail {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+  background: var(--miu-bg);
+}
+.miu-detail {
+  display: flex;
+  flex-direction: column;
+  height: 100%;
+  min-height: 0;
+}
+.miu-detail-actions {
+  display: flex;
+  justify-content: flex-end;
+  gap: 6px;
+  padding: 10px 14px;
+  border-bottom: 1px solid var(--miu-border);
+}
+.miu-detail-body {
+  padding: 22px;
+}
+.miu-detail-title {
+  font-weight: 700;
+  font-size: 16px;
+  margin-bottom: 6px;
+}
+.miu-detail-summary {
+  color: var(--miu-muted);
+  line-height: 1.55;
+}
+
+/* mail reader */
+.miu-mail {
+  display: flex;
+  flex-direction: column;
+  height: 100%;
+  min-height: 0;
+}
+.miu-mail-head {
+  padding: 12px 18px;
+  border-bottom: 1px solid var(--miu-border);
+  font-weight: 700;
+  font-size: 15px;
+}
+.miu-mail-body {
+  flex: 1;
+  min-height: 0;
+  overflow-y: auto;
+  padding: 16px;
+  display: flex;
+  flex-direction: column;
+  gap: 12px;
+}
+.miu-mail-msg {
+  border: 1px solid var(--miu-border);
+  border-radius: var(--miu-radius);
+  background: var(--miu-panel);
+  overflow: hidden;
+}
+.miu-mail-meta {
+  display: flex;
+  justify-content: space-between;
+  padding: 7px 12px;
+  border-bottom: 1px solid var(--miu-border);
+  font-size: 12px;
+  color: var(--miu-muted);
+}
+.miu-mail-frame {
+  width: 100%;
+  height: 200px;
+  border: none;
+  background: #fff;
+}
+.miu-mail-text {
+  padding: 12px;
+  white-space: pre-wrap;
+  word-break: break-word;
+}
+
+/* compose modal — portaled to <body>, so carry SDK theme-token defaults here (the host's
+   own token mapping + a synchronous copy on the portal root override these). */
+.miu-portal {
+  --miu-bg: #0e0e13;
+  --miu-panel: #16161d;
+  --miu-panel-2: #1d1d26;
+  --miu-border: #262631;
+  --miu-text: #e9e9ef;
+  --miu-muted: #9a9aa7;
+  --miu-accent: #fda913;
+  --miu-accent-text: #1a1206;
+  --miu-radius: 12px;
+}
+.miu-modal-overlay {
+  position: fixed;
+  inset: 0;
+  z-index: 2147483000;
+  background: rgba(2, 2, 6, 0.6);
+  display: grid;
+  place-items: center;
+  padding: 20px;
+}
+.miu-modal {
+  width: 100%;
+  max-width: 520px;
+  max-height: 88vh;
+  display: flex;
+  flex-direction: column;
+  border: 1px solid var(--miu-border);
+  border-radius: 16px;
+  background: var(--miu-panel);
+  color: var(--miu-text);
+  font-family: system-ui, -apple-system, 'Segoe UI', sans-serif;
+}
+.miu-modal-head {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 16px 18px;
+  border-bottom: 1px solid var(--miu-border);
+  font-weight: 700;
+}
+.miu-modal-body {
+  padding: 16px 18px;
+  overflow-y: auto;
+  display: flex;
+  flex-direction: column;
+  gap: 12px;
+}
+.miu-modal-foot {
+  display: flex;
+  justify-content: flex-end;
+  gap: 8px;
+  padding: 14px 18px;
+  border-top: 1px solid var(--miu-border);
+}
+.miu-compose-modes {
+  display: flex;
+  gap: 6px;
+}
+.miu-field {
+  display: flex;
+  flex-direction: column;
+  gap: 6px;
+}
+.miu-field-lbl {
+  font-size: 12.5px;
+  font-weight: 600;
+  color: var(--miu-muted);
+}
+.miu-textarea {
+  resize: vertical;
+  min-height: 90px;
+}
+.miu-people {
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+  max-height: 180px;
+  overflow-y: auto;
+}
+.miu-person {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  padding: 7px 10px;
+  border-radius: 10px;
+  cursor: pointer;
+}
+.miu-person.is-active {
+  background: var(--miu-panel-2);
+}
+.miu-person span:nth-of-type(1) {
+  flex: 1;
+}
+
+/* misc */
+.miu-empty {
+  padding: 24px;
+  color: var(--miu-muted);
+  text-align: center;
+}
+.miu-thread-empty {
+  margin: auto;
+}
+.miu-error {
+  color: #f0563f;
+}
diff --git a/packages/iios-messaging-ui/src/test-setup.ts b/packages/iios-messaging-ui/src/test-setup.ts
new file mode 100644
index 0000000..8919f3f
--- /dev/null
+++ b/packages/iios-messaging-ui/src/test-setup.ts
@@ -0,0 +1,8 @@
+import { afterEach } from 'vitest';
+import { cleanup } from '@testing-library/react';
+
+// @testing-library/react auto-registers cleanup only when afterEach is a global.
+// We run with globals: false, so register it explicitly.
+afterEach(() => {
+  cleanup();
+});
diff --git a/packages/iios-messaging-ui/src/types.test.ts b/packages/iios-messaging-ui/src/types.test.ts
new file mode 100644
index 0000000..da334a2
--- /dev/null
+++ b/packages/iios-messaging-ui/src/types.test.ts
@@ -0,0 +1,28 @@
+import { describe, it, expect } from 'vitest';
+import { isOwnMessage } from './types';
+import type { Message } from './types';
+
+const base: Message = {
+  id: 'm1',
+  actorId: 'actor_a',
+  text: 'hello',
+  at: '2026-07-17T10:00:00.000Z',
+};
+
+describe('isOwnMessage', () => {
+  it('is true when the message actor matches the current actor', () => {
+    expect(isOwnMessage(base, 'actor_a')).toBe(true);
+  });
+
+  it('is false when the actors differ', () => {
+    expect(isOwnMessage(base, 'actor_b')).toBe(false);
+  });
+
+  it('is false when the current actor is unknown', () => {
+    expect(isOwnMessage(base, null)).toBe(false);
+  });
+
+  it('is false when the message has no actor', () => {
+    expect(isOwnMessage({ ...base, actorId: null }, 'actor_a')).toBe(false);
+  });
+});
diff --git a/packages/iios-messaging-ui/src/types.ts b/packages/iios-messaging-ui/src/types.ts
new file mode 100644
index 0000000..0c1d918
--- /dev/null
+++ b/packages/iios-messaging-ui/src/types.ts
@@ -0,0 +1,87 @@
+// Domain types for the messaging UI. Zero imports on purpose: this file must never
+// reach for a transport package. Adapters map their own DTOs onto these.
+
+export type Membership = 'dm' | 'group' | 'channel';
+
+export type ChannelVisibility = 'public' | 'private';
+
+export interface Person {
+  id: string;
+  name: string;
+  kind: 'staff' | 'customer';
+}
+
+export interface Conversation {
+  threadId: string;
+  title: string;
+  subject: string | null;
+  membership: Membership | null;
+  participants: string[];
+  unread: number;
+  lastMessage?: string;
+  lastAt?: string;
+  /** Channel description (channels only). */
+  topic?: string | null;
+}
+
+/** A discoverable channel (from browseChannels) — includes ones the caller has NOT joined. */
+export interface ChannelSummary {
+  threadId: string;
+  name: string;
+  topic: string | null;
+  visibility: ChannelVisibility;
+  memberCount: number;
+  /** True if the current user is already a member. */
+  joined: boolean;
+}
+
+export interface CreateChannelInput {
+  name: string;
+  topic?: string;
+  visibility: ChannelVisibility;
+}
+
+export interface Reaction {
+  emoji: string;
+  count: number;
+  mine: boolean;
+}
+
+export interface Attachment {
+  url: string;
+  mime: string;
+  name: string;
+}
+
+export interface Message {
+  id: string;
+  actorId: string | null;
+  text: string;
+  at: string;
+  parentInteractionId?: string | null;
+  reactions?: Reaction[];
+  attachment?: Attachment;
+  /** True only when the transport is optimistic-local and not yet acknowledged. */
+  pending?: boolean;
+}
+
+export interface SendOpts {
+  parentInteractionId?: string;
+  attachment?: Attachment;
+  /** Opaque userId notify-list (from @mentions). The app parses "@"; the kernel just forwards it. */
+  mentions?: string[];
+}
+
+export type MessageEvent =
+  | { kind: 'message'; message: Message }
+  | { kind: 'typing'; userId: string }
+  | { kind: 'receipt'; messageId: string; actorId: string }
+  | { kind: 'reaction'; messageId: string; reactions: Reaction[] };
+
+export type Unsubscribe = () => void;
+
+/** Ownership is a pure function of explicit identity — never inferred from history.
+ *  See the spec: inferring it is the bug this SDK exists partly to kill. */
+export function isOwnMessage(message: Message, currentActorId: string | null): boolean {
+  return currentActorId !== null && message.actorId !== null && message.actorId === currentActorId;
+}
diff --git a/packages/iios-messaging-ui/tsconfig.json b/packages/iios-messaging-ui/tsconfig.json
new file mode 100644
index 0000000..4a4d5c4
--- /dev/null
+++ b/packages/iios-messaging-ui/tsconfig.json
@@ -0,0 +1,14 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "outDir": "./dist",
+    "rootDir": "./src",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "lib": ["ES2022", "DOM"],
+    "jsx": "react-jsx",
+    "types": ["react"]
+  },
+  "include": ["src/**/*.ts", "src/**/*.tsx"],
+  "exclude": ["src/**/*.test.ts", "src/**/*.test.tsx"]
+}
diff --git a/packages/iios-messaging-ui/tsup.config.ts b/packages/iios-messaging-ui/tsup.config.ts
new file mode 100644
index 0000000..0a8aa58
--- /dev/null
+++ b/packages/iios-messaging-ui/tsup.config.ts
@@ -0,0 +1,15 @@
+import { defineConfig } from 'tsup';
+
+export default defineConfig({
+  // `src/adapters/mock.ts` and `src/conformance.ts` are added as separate entries
+  // in later tasks (they don't exist yet). `conformance` in particular is its own
+  // entry, never reachable from `index`, because it imports vitest, and bundling
+  // that into the main barrel would drag a test runner into every consumer's
+  // production build.
+  entry: ['src/index.ts', 'src/adapters/mock.ts', 'src/adapters/mock-inbox.ts', 'src/adapters/kernel-client.ts', 'src/conformance.ts', 'src/styles.css'],
+  format: ['esm'],
+  // Types only for the TS entries — styles.css has no .d.ts (and tsc chokes on a .css root file).
+  dts: { entry: ['src/index.ts', 'src/adapters/mock.ts', 'src/adapters/mock-inbox.ts', 'src/adapters/kernel-client.ts', 'src/conformance.ts'] },
+  clean: true,
+  external: ['react', 'react-dom', 'vitest', '@insignia/iios-kernel-client'],
+});
diff --git a/packages/iios-messaging-ui/vitest.config.ts b/packages/iios-messaging-ui/vitest.config.ts
new file mode 100644
index 0000000..853c7e8
--- /dev/null
+++ b/packages/iios-messaging-ui/vitest.config.ts
@@ -0,0 +1,13 @@
+import { defineConfig } from 'vitest/config';
+
+// This package owns its vitest config on purpose. The ROOT config includes only
+// `.ts` (never `.tsx`) and provisions a Postgres DB via globalSetup for every run —
+// a pure-UI package must not drag a database along, and its tests are .tsx.
+export default defineConfig({
+  test: {
+    environment: 'jsdom',
+    include: ['src/**/*.{test,spec}.{ts,tsx}'],
+    setupFiles: ['./src/test-setup.ts'],
+    globals: false,
+  },
+});
diff --git a/packages/iios-service/prisma/migrations/20260722101158_provider_credentials/migration.sql b/packages/iios-service/prisma/migrations/20260722101158_provider_credentials/migration.sql
new file mode 100644
index 0000000..f1f7b2b
--- /dev/null
+++ b/packages/iios-service/prisma/migrations/20260722101158_provider_credentials/migration.sql
@@ -0,0 +1,26 @@
+-- CreateTable
+CREATE TABLE "IiosProviderCredential" (
+    "id" TEXT NOT NULL,
+    "scopeId" TEXT NOT NULL,
+    "providerType" TEXT NOT NULL,
+    "cipherText" TEXT NOT NULL,
+    "iv" TEXT NOT NULL,
+    "authTag" TEXT NOT NULL,
+    "keyVersion" INTEGER NOT NULL DEFAULT 1,
+    "displayHints" JSONB,
+    "enabled" BOOLEAN NOT NULL DEFAULT true,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "IiosProviderCredential_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "IiosProviderCredential_scopeId_idx" ON "IiosProviderCredential"("scopeId");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "IiosProviderCredential_scopeId_providerType_key" ON "IiosProviderCredential"("scopeId", "providerType");
+
+-- AddForeignKey
+ALTER TABLE "IiosProviderCredential" ADD CONSTRAINT "IiosProviderCredential_scopeId_fkey" FOREIGN KEY ("scopeId") REFERENCES "IiosScope"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
diff --git a/packages/iios-service/prisma/schema.prisma b/packages/iios-service/prisma/schema.prisma
index bda1038..799aeeb 100644
--- a/packages/iios-service/prisma/schema.prisma
+++ b/packages/iios-service/prisma/schema.prisma
@@ -317,10 +317,33 @@ model IiosScope {
   callbacks     IiosCallbackRequest[]
   notificationSubscriptions IiosNotificationSubscription[]
   messageTemplates IiosMessageTemplate[]
+  providerCredentials IiosProviderCredential[]
 
   @@index([orgId, appId, tenantId])
 }
 
+/// A tenant's own credentials for an egress provider (BYO: Twilio SMS, own SMTP, …).
+/// The secret is sealed with AES-256-GCM under the platform key (IIOS_CRED_KEY); only
+/// `displayHints` (non-secret, e.g. from-number / SID last-4) is ever read back out.
+/// One row per (scope, providerType). Resolved at send time by the channel's provider.
+model IiosProviderCredential {
+  id           String    @id @default(cuid())
+  scopeId      String
+  scope        IiosScope @relation(fields: [scopeId], references: [id], onDelete: Cascade)
+  providerType String    // TWILIO_SMS | SMTP | WHATSAPP_CLOUD | …
+  cipherText   String    // base64(AES-256-GCM ciphertext of the JSON config)
+  iv           String    // base64 nonce
+  authTag      String    // base64 GCM auth tag
+  keyVersion   Int       @default(1)
+  displayHints Json?     // non-secret display fields (fromNumber, sidLast4, …)
+  enabled      Boolean   @default(true)
+  createdAt    DateTime  @default(now())
+  updatedAt    DateTime  @updatedAt
+
+  @@unique([scopeId, providerType])
+  @@index([scopeId])
+}
+
 /// A channel-specific handle (phone/email/portal user). NOT identity — stays
 /// UNVERIFIED until MDM resolves it; no silent merge.
 model IiosSourceHandle {
diff --git a/packages/iios-service/src/capability/capability.module.ts b/packages/iios-service/src/capability/capability.module.ts
index 6eac20c..4c27fa0 100644
--- a/packages/iios-service/src/capability/capability.module.ts
+++ b/packages/iios-service/src/capability/capability.module.ts
@@ -2,15 +2,20 @@ import { Module } from '@nestjs/common';
 import { MediaModule } from '../media/media.module';
 import { CapabilityProviderRegistry } from './capability.registry';
 import { CapabilityBroker } from './capability.broker';
+import { ProviderCredentialService } from './provider-credential.service';
+import { ProviderCredentialController } from './provider-credential.controller';
 
 /**
  * The governed egress boundary (P9 slice 1). Exports the broker + registry so the
  * outbound layer routes all sends through policy + obligations + a pluggable
  * provider. PLATFORM_PORTS (for the opa gate) comes from the @Global PlatformModule.
+ * Also owns per-scope BYO provider credentials (Twilio SMS, …) — sealed at rest and
+ * resolved by the channel providers at send time.
  */
 @Module({
   imports: [MediaModule],
-  providers: [CapabilityProviderRegistry, CapabilityBroker],
-  exports: [CapabilityBroker, CapabilityProviderRegistry],
+  controllers: [ProviderCredentialController],
+  providers: [CapabilityProviderRegistry, CapabilityBroker, ProviderCredentialService],
+  exports: [CapabilityBroker, CapabilityProviderRegistry, ProviderCredentialService],
 })
 export class CapabilityModule {}
diff --git a/packages/iios-service/src/capability/capability.registry.ts b/packages/iios-service/src/capability/capability.registry.ts
index 4728e7a..76b32a0 100644
--- a/packages/iios-service/src/capability/capability.registry.ts
+++ b/packages/iios-service/src/capability/capability.registry.ts
@@ -4,6 +4,9 @@ import { SandboxProvider } from './sandbox.provider';
 import { HttpProvider } from './http.provider';
 import { EmailProvider } from './email.provider';
 import { SmtpProvider, smtpFallbackFromEnv, smtpIdentityFromEnv, storageResolver } from './smtp.provider';
+import { TwilioSmsProvider, type TwilioCreds } from './twilio-sms.provider';
+import { credKeyFromEnv } from './secret-crypto';
+import { ProviderCredentialService } from './provider-credential.service';
 import { STORAGE_PORT, type StoragePort } from '../media/storage.port';
 
 const DEFAULT_CHANNELS = ['WEBHOOK', 'EMAIL', 'SMS', 'WHATSAPP', 'PORTAL'];
@@ -21,7 +24,10 @@ const DEFAULT_CHANNELS = ['WEBHOOK', 'EMAIL', 'SMS', 'WHATSAPP', 'PORTAL'];
 export class CapabilityProviderRegistry {
   private readonly byChannel = new Map<string, CapabilityProvider>();
 
-  constructor(@Optional() @Inject(STORAGE_PORT) private readonly storage?: StoragePort) {
+  constructor(
+    @Optional() @Inject(STORAGE_PORT) private readonly storage?: StoragePort,
+    @Optional() private readonly credentials?: ProviderCredentialService,
+  ) {
     for (const ch of DEFAULT_CHANNELS) this.register(new SandboxProvider([ch]));
     for (const ch of DEFAULT_CHANNELS) {
       const url = process.env[`IIOS_PROVIDER_URL_${ch}`];
@@ -36,6 +42,12 @@ export class CapabilityProviderRegistry {
       const resolver = this.storage ? storageResolver(this.storage) : undefined;
       this.register(new SmtpProvider(smtp, smtpFallbackFromEnv() ?? undefined, undefined, resolver));
     }
+    // BYO SMS via each tenant's own Twilio creds (resolved per scope at send time). Registered
+    // only when the platform key + credential store are present — else SMS stays on the sandbox.
+    if (credKeyFromEnv() && this.credentials) {
+      const creds = this.credentials;
+      this.register(new TwilioSmsProvider((scopeId) => creds.resolve(scopeId, 'TWILIO_SMS') as Promise<TwilioCreds | null>));
+    }
   }
 
   register(provider: CapabilityProvider): void {
diff --git a/packages/iios-service/src/capability/provider-credential.controller.ts b/packages/iios-service/src/capability/provider-credential.controller.ts
new file mode 100644
index 0000000..8b69fb1
--- /dev/null
+++ b/packages/iios-service/src/capability/provider-credential.controller.ts
@@ -0,0 +1,54 @@
+import { BadRequestException, Body, Controller, Get, Headers, Param, Put } from '@nestjs/common';
+import { SessionVerifier } from '../platform/session.verifier';
+import { ActorResolver, type MessagePrincipal } from '../identity/actor.resolver';
+import { ProviderCredentialService } from './provider-credential.service';
+import { TwilioCredentialsDto } from './provider-credential.dto';
+
+const SUPPORTED = new Set(['TWILIO_SMS']);
+
+/**
+ * Per-scope BYO integration credentials. The caller's attested session decides the scope, so a
+ * tenant can only read/write ITS OWN provider credentials. The secret is sealed by the service;
+ * GET returns a masked status (never the token). be-crm gates this behind tenant-admin policy.
+ */
+@Controller('v1/providers')
+export class ProviderCredentialController {
+  constructor(
+    private readonly session: SessionVerifier,
+    private readonly actors: ActorResolver,
+    private readonly credentials: ProviderCredentialService,
+  ) {}
+
+  @Put(':providerType/credentials')
+  async put(
+    @Param('providerType') providerType: string,
+    @Body() body: TwilioCredentialsDto,
+    @Headers('authorization') authorization?: string,
+  ) {
+    this.assertSupported(providerType);
+    const scope = await this.actors.resolveScope(this.principal(authorization));
+    await this.credentials.upsert(scope.id, providerType, {
+      accountSid: body.accountSid,
+      authToken: body.authToken,
+      fromNumber: body.fromNumber,
+    });
+    return this.credentials.status(scope.id, providerType);
+  }
+
+  @Get(':providerType/credentials')
+  async get(@Param('providerType') providerType: string, @Headers('authorization') authorization?: string) {
+    this.assertSupported(providerType);
+    const scope = await this.actors.resolveScope(this.principal(authorization));
+    return this.credentials.status(scope.id, providerType);
+  }
+
+  private assertSupported(providerType: string): void {
+    if (!SUPPORTED.has(providerType)) throw new BadRequestException(`unsupported providerType: ${providerType}`);
+  }
+
+  private principal(authorization?: string): MessagePrincipal {
+    const token = (authorization ?? '').replace(/^Bearer\s+/i, '');
+    if (!token) throw new BadRequestException('Authorization bearer token is required');
+    return this.session.verify(token);
+  }
+}
diff --git a/packages/iios-service/src/capability/provider-credential.dto.ts b/packages/iios-service/src/capability/provider-credential.dto.ts
new file mode 100644
index 0000000..75c88e9
--- /dev/null
+++ b/packages/iios-service/src/capability/provider-credential.dto.ts
@@ -0,0 +1,11 @@
+import { IsNotEmpty, IsString } from 'class-validator';
+
+/**
+ * PUT /v1/providers/TWILIO_SMS/credentials — a tenant's own Twilio credentials. Step 1 supports
+ * TWILIO_SMS only; when a second provider (SMTP, …) is added, switch to a per-type validated body.
+ */
+export class TwilioCredentialsDto {
+  @IsString() @IsNotEmpty() accountSid!: string;
+  @IsString() @IsNotEmpty() authToken!: string;
+  @IsString() @IsNotEmpty() fromNumber!: string;
+}
diff --git a/packages/iios-service/src/capability/provider-credential.service.spec.ts b/packages/iios-service/src/capability/provider-credential.service.spec.ts
new file mode 100644
index 0000000..41aff22
--- /dev/null
+++ b/packages/iios-service/src/capability/provider-credential.service.spec.ts
@@ -0,0 +1,79 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { ProviderCredentialService } from './provider-credential.service';
+
+const KEY_B64 = Buffer.alloc(32, 7).toString('base64');
+
+/** Minimal in-memory stand-in for prisma.iiosProviderCredential (upsert/findUnique). */
+function fakePrisma() {
+  const rows = new Map<string, Record<string, unknown>>();
+  const k = (scopeId: string, providerType: string) => `${scopeId}::${providerType}`;
+  return {
+    _rows: rows,
+    iiosProviderCredential: {
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      async upsert({ where, create, update }: any) {
+        const key = k(where.scopeId_providerType.scopeId, where.scopeId_providerType.providerType);
+        const existing = rows.get(key);
+        const row = existing ? { ...existing, ...update } : { ...create };
+        rows.set(key, row);
+        return row;
+      },
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      async findUnique({ where }: any) {
+        return rows.get(k(where.scopeId_providerType.scopeId, where.scopeId_providerType.providerType)) ?? null;
+      },
+    },
+  };
+}
+
+function make(prisma: ReturnType<typeof fakePrisma>, env: NodeJS.ProcessEnv): ProviderCredentialService {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const s = new ProviderCredentialService(prisma as any);
+  s.env = env;
+  return s;
+}
+
+describe('ProviderCredentialService', () => {
+  let prisma: ReturnType<typeof fakePrisma>;
+  let svc: ProviderCredentialService;
+
+  beforeEach(() => {
+    prisma = fakePrisma();
+    svc = make(prisma, { IIOS_CRED_KEY: KEY_B64 } as NodeJS.ProcessEnv);
+  });
+
+  it('seals the secret at rest — plaintext token never stored', async () => {
+    await svc.upsert('scope_1', 'TWILIO_SMS', { accountSid: 'AC123', authToken: 'tok_secret', fromNumber: '+15550001111' });
+    const stored = JSON.stringify([...prisma._rows.values()]);
+    expect(stored).not.toContain('tok_secret');
+    expect(stored).toContain('cipherText');
+  });
+
+  it('resolves back the exact config it sealed', async () => {
+    const cfg = { accountSid: 'AC123', authToken: 'tok_secret', fromNumber: '+15550001111' };
+    await svc.upsert('scope_1', 'TWILIO_SMS', cfg);
+    expect(await svc.resolve('scope_1', 'TWILIO_SMS')).toEqual(cfg);
+  });
+
+  it('status is masked — reveals hints, never the token', async () => {
+    await svc.upsert('scope_1', 'TWILIO_SMS', { accountSid: 'AC1234567', authToken: 'tok_secret', fromNumber: '+15550001111' });
+    const status = await svc.status('scope_1', 'TWILIO_SMS');
+    expect(status).toMatchObject({ configured: true, enabled: true, hints: { fromNumber: '+15550001111', sidLast4: '4567' } });
+    expect(JSON.stringify(status)).not.toContain('tok_secret');
+  });
+
+  it('reports not-configured for an unknown scope', async () => {
+    expect(await svc.status('nope', 'TWILIO_SMS')).toEqual({ configured: false });
+    expect(await svc.resolve('nope', 'TWILIO_SMS')).toBeNull();
+  });
+
+  it('does not resolve a disabled credential', async () => {
+    await svc.upsert('scope_1', 'TWILIO_SMS', { accountSid: 'AC123', authToken: 't', fromNumber: '+1' }, { enabled: false });
+    expect(await svc.resolve('scope_1', 'TWILIO_SMS')).toBeNull();
+  });
+
+  it('throws when the platform key is absent (fail closed, never store plaintext)', async () => {
+    const noKey = make(prisma, {} as NodeJS.ProcessEnv);
+    await expect(noKey.upsert('s', 'TWILIO_SMS', { accountSid: 'A', authToken: 't', fromNumber: '+1' })).rejects.toThrow(/IIOS_CRED_KEY/);
+  });
+});
diff --git a/packages/iios-service/src/capability/provider-credential.service.ts b/packages/iios-service/src/capability/provider-credential.service.ts
new file mode 100644
index 0000000..574913b
--- /dev/null
+++ b/packages/iios-service/src/capability/provider-credential.service.ts
@@ -0,0 +1,70 @@
+import { BadRequestException, Injectable } from '@nestjs/common';
+import { Prisma } from '@prisma/client';
+import { PrismaService } from '../prisma/prisma.service';
+import { credKeyFromEnv, sealSecret, openSecret, type SealedSecret } from './secret-crypto';
+
+/** A provider config is an opaque JSON bag; each provider knows its own shape. */
+export type ProviderConfig = Record<string, unknown>;
+
+export interface CredentialStatus {
+  configured: boolean;
+  enabled?: boolean;
+  hints?: Record<string, unknown>;
+}
+
+/** Non-secret display fields surfaced by `status` — NEVER the secret itself. */
+function hintsFor(providerType: string, config: ProviderConfig): Record<string, unknown> {
+  if (providerType === 'TWILIO_SMS') {
+    const sid = String(config.accountSid ?? '');
+    return { fromNumber: config.fromNumber ?? null, sidLast4: sid.slice(-4) };
+  }
+  return {};
+}
+
+/**
+ * The tenant's BYO integration credentials, one row per (scope, providerType). The secret is
+ * sealed with AES-256-GCM under the platform key before it touches the DB; only non-secret
+ * `displayHints` are ever read back. `resolve` decrypts on demand at send time; `status` never
+ * returns the secret. Fail-closed: no platform key ⇒ upsert throws (we refuse to store plaintext).
+ */
+@Injectable()
+export class ProviderCredentialService {
+  /** Overridable in tests; defaults to the process env (holds IIOS_CRED_KEY). */
+  env: NodeJS.ProcessEnv = process.env;
+
+  constructor(private readonly prisma: PrismaService) {}
+
+  async upsert(scopeId: string, providerType: string, config: ProviderConfig, opts?: { enabled?: boolean }): Promise<void> {
+    const key = credKeyFromEnv(this.env);
+    if (!key) throw new BadRequestException('IIOS_CRED_KEY is not configured — cannot store integration credentials');
+    const sealed = sealSecret(JSON.stringify(config), key);
+    const enabled = opts?.enabled ?? true;
+    const displayHints = hintsFor(providerType, config) as Prisma.InputJsonValue;
+    await this.prisma.iiosProviderCredential.upsert({
+      where: { scopeId_providerType: { scopeId, providerType } },
+      create: { scopeId, providerType, ...sealed, displayHints, enabled },
+      update: { ...sealed, displayHints, enabled },
+    });
+  }
+
+  /** Decrypt the config for send-time use. Null when unconfigured, disabled, or no key. */
+  async resolve(scopeId: string, providerType: string): Promise<ProviderConfig | null> {
+    const row = await this.prisma.iiosProviderCredential.findUnique({
+      where: { scopeId_providerType: { scopeId, providerType } },
+    });
+    if (!row || !row.enabled) return null;
+    const key = credKeyFromEnv(this.env);
+    if (!key) return null;
+    const sealed: SealedSecret = { cipherText: row.cipherText, iv: row.iv, authTag: row.authTag, keyVersion: row.keyVersion };
+    return JSON.parse(openSecret(sealed, key)) as ProviderConfig;
+  }
+
+  /** Masked view for the admin UI — configured + hints, never the secret. */
+  async status(scopeId: string, providerType: string): Promise<CredentialStatus> {
+    const row = await this.prisma.iiosProviderCredential.findUnique({
+      where: { scopeId_providerType: { scopeId, providerType } },
+    });
+    if (!row) return { configured: false };
+    return { configured: true, enabled: row.enabled, hints: (row.displayHints ?? {}) as Record<string, unknown> };
+  }
+}
diff --git a/packages/iios-service/src/capability/secret-crypto.spec.ts b/packages/iios-service/src/capability/secret-crypto.spec.ts
new file mode 100644
index 0000000..2a17965
--- /dev/null
+++ b/packages/iios-service/src/capability/secret-crypto.spec.ts
@@ -0,0 +1,38 @@
+import { describe, it, expect } from 'vitest';
+import { credKeyFromEnv, sealSecret, openSecret, SECRET_KEY_VERSION } from './secret-crypto';
+
+const KEY = Buffer.alloc(32, 7); // deterministic 32-byte key for tests
+
+describe('secret-crypto', () => {
+  it('round-trips a secret through seal → open', () => {
+    const sealed = sealSecret('sk_live_abc123', KEY);
+    expect(sealed.keyVersion).toBe(SECRET_KEY_VERSION);
+    expect(sealed.cipherText).not.toContain('sk_live_abc123');
+    expect(openSecret(sealed, KEY)).toBe('sk_live_abc123');
+  });
+
+  it('produces a distinct ciphertext each time (random IV)', () => {
+    const a = sealSecret('same', KEY);
+    const b = sealSecret('same', KEY);
+    expect(a.cipherText).not.toBe(b.cipherText);
+    expect(a.iv).not.toBe(b.iv);
+  });
+
+  it('fails to open with the wrong key', () => {
+    const sealed = sealSecret('top-secret', KEY);
+    expect(() => openSecret(sealed, Buffer.alloc(32, 9))).toThrow();
+  });
+
+  it('fails to open if the ciphertext is tampered (GCM auth)', () => {
+    const sealed = sealSecret('top-secret', KEY);
+    const bad = { ...sealed, cipherText: Buffer.from('deadbeef', 'hex').toString('base64') };
+    expect(() => openSecret(bad, KEY)).toThrow();
+  });
+
+  it('credKeyFromEnv returns null when unset and rejects a wrong-length key', () => {
+    expect(credKeyFromEnv({})).toBeNull();
+    expect(() => credKeyFromEnv({ IIOS_CRED_KEY: Buffer.alloc(16).toString('base64') })).toThrow(/32 bytes/);
+    const key = credKeyFromEnv({ IIOS_CRED_KEY: KEY.toString('base64') });
+    expect(key?.length).toBe(32);
+  });
+});
diff --git a/packages/iios-service/src/capability/secret-crypto.ts b/packages/iios-service/src/capability/secret-crypto.ts
new file mode 100644
index 0000000..403606c
--- /dev/null
+++ b/packages/iios-service/src/capability/secret-crypto.ts
@@ -0,0 +1,46 @@
+import { createCipheriv, createDecipheriv, randomBytes } from 'node:crypto';
+
+/**
+ * Envelope for a tenant secret sealed with AES-256-GCM. Stored as base64 columns on
+ * IiosProviderCredential; the plaintext (a provider config JSON string) never touches disk.
+ */
+export interface SealedSecret {
+  cipherText: string;
+  iv: string;
+  authTag: string;
+  keyVersion: number;
+}
+
+/** Bumped only when the platform master key rotates; lets old rows decrypt under an old key. */
+export const SECRET_KEY_VERSION = 1;
+
+/**
+ * Resolve the 32-byte platform master key from `IIOS_CRED_KEY` (base64). Returns null when
+ * unset (so egress providers that need it stay unregistered / fail closed) but THROWS on a
+ * present-but-malformed key — a wrong-length key is an operator error, not a "disabled" state.
+ */
+export function credKeyFromEnv(env: NodeJS.ProcessEnv = process.env): Buffer | null {
+  const raw = env.IIOS_CRED_KEY;
+  if (!raw) return null;
+  const key = Buffer.from(raw, 'base64');
+  if (key.length !== 32) throw new Error('IIOS_CRED_KEY must decode to 32 bytes (base64-encoded 256-bit key)');
+  return key;
+}
+
+export function sealSecret(plaintext: string, key: Buffer): SealedSecret {
+  const iv = randomBytes(12);
+  const cipher = createCipheriv('aes-256-gcm', key, iv);
+  const enc = Buffer.concat([cipher.update(plaintext, 'utf8'), cipher.final()]);
+  return {
+    cipherText: enc.toString('base64'),
+    iv: iv.toString('base64'),
+    authTag: cipher.getAuthTag().toString('base64'),
+    keyVersion: SECRET_KEY_VERSION,
+  };
+}
+
+export function openSecret(sealed: SealedSecret, key: Buffer): string {
+  const decipher = createDecipheriv('aes-256-gcm', key, Buffer.from(sealed.iv, 'base64'));
+  decipher.setAuthTag(Buffer.from(sealed.authTag, 'base64'));
+  return Buffer.concat([decipher.update(Buffer.from(sealed.cipherText, 'base64')), decipher.final()]).toString('utf8');
+}
diff --git a/packages/iios-service/src/capability/twilio-sms.provider.spec.ts b/packages/iios-service/src/capability/twilio-sms.provider.spec.ts
new file mode 100644
index 0000000..4c25bd5
--- /dev/null
+++ b/packages/iios-service/src/capability/twilio-sms.provider.spec.ts
@@ -0,0 +1,67 @@
+import { describe, it, expect, vi } from 'vitest';
+import type { CapabilityRequest } from '@insignia/iios-contracts';
+import { TwilioSmsProvider, type TwilioCreds } from './twilio-sms.provider';
+
+const CREDS: TwilioCreds = { accountSid: 'AC123', authToken: 'tok_secret', fromNumber: '+15550001111' };
+
+const req = (over: Partial<CapabilityRequest> = {}): CapabilityRequest => ({
+  capability: 'channel.send',
+  channelType: 'SMS',
+  scopeId: 'scope_1',
+  target: '+15557654321',
+  payload: { text: 'hello world' },
+  idempotencyKey: 'idem-1',
+  ...over,
+});
+
+describe('TwilioSmsProvider', () => {
+  it('resolves the scope creds and POSTs to Twilio, returning SENT with the message SID', async () => {
+    const http = vi.fn().mockResolvedValue({ ok: true, status: 201, json: async () => ({ sid: 'SM999' }), text: async () => '' });
+    const resolve = vi.fn().mockResolvedValue(CREDS);
+    const p = new TwilioSmsProvider(resolve, http);
+
+    const res = await p.send(req());
+
+    expect(resolve).toHaveBeenCalledWith('scope_1');
+    const [url, init] = http.mock.calls[0];
+    expect(url).toBe('https://api.twilio.com/2010-04-01/Accounts/AC123/Messages.json');
+    expect(init.method).toBe('POST');
+    expect(init.headers.authorization).toBe(`Basic ${Buffer.from('AC123:tok_secret').toString('base64')}`);
+    const body = new URLSearchParams(init.body as string);
+    expect(body.get('To')).toBe('+15557654321');
+    expect(body.get('From')).toBe('+15550001111');
+    expect(body.get('Body')).toBe('hello world');
+    expect(res).toMatchObject({ outcome: 'SENT', providerRef: 'SM999' });
+  });
+
+  it('fails closed as NOT_CONFIGURED when the scope has no creds', async () => {
+    const http = vi.fn();
+    const p = new TwilioSmsProvider(async () => null, http);
+    const res = await p.send(req());
+    expect(res.outcome).toBe('FAILED');
+    expect(res.errorCode).toBe('NOT_CONFIGURED');
+    expect(http).not.toHaveBeenCalled();
+  });
+
+  it('fails closed as NOT_CONFIGURED when the request has no scope', async () => {
+    const p = new TwilioSmsProvider(async () => CREDS, vi.fn());
+    const res = await p.send(req({ scopeId: undefined }));
+    expect(res.outcome).toBe('FAILED');
+    expect(res.errorCode).toBe('NOT_CONFIGURED');
+  });
+
+  it('surfaces a Twilio API error as FAILED (never throws)', async () => {
+    const http = vi.fn().mockResolvedValue({ ok: false, status: 401, json: async () => ({ code: 20003, message: 'Authenticate' }), text: async () => 'Authenticate' });
+    const p = new TwilioSmsProvider(async () => CREDS, http);
+    const res = await p.send(req());
+    expect(res.outcome).toBe('FAILED');
+    expect(res.errorCode).toBe('TWILIO_20003');
+  });
+
+  it('surfaces a transport throw as FAILED', async () => {
+    const http = vi.fn().mockRejectedValue(new Error('network down'));
+    const p = new TwilioSmsProvider(async () => CREDS, http);
+    const res = await p.send(req());
+    expect(res.outcome).toBe('FAILED');
+  });
+});
diff --git a/packages/iios-service/src/capability/twilio-sms.provider.ts b/packages/iios-service/src/capability/twilio-sms.provider.ts
new file mode 100644
index 0000000..d1a2d4b
--- /dev/null
+++ b/packages/iios-service/src/capability/twilio-sms.provider.ts
@@ -0,0 +1,70 @@
+import type { CapabilityProvider, CapabilityRequest, ProviderResult } from '@insignia/iios-contracts';
+
+/** The decrypted Twilio config a tenant configures (BYO credentials). */
+export interface TwilioCreds {
+  accountSid: string;
+  authToken: string;
+  fromNumber: string;
+}
+
+/** Resolves a scope's Twilio creds (decrypting on demand); null when unconfigured/disabled. */
+export type TwilioCredResolver = (scopeId: string) => Promise<TwilioCreds | null>;
+
+/** Injectable HTTP sender so tests don't hit the network; prod uses fetch. */
+export type HttpSender = (url: string, init: { method: string; headers: Record<string, string>; body: string }) => Promise<{
+  ok: boolean;
+  status: number;
+  json: () => Promise<unknown>;
+  text: () => Promise<string>;
+}>;
+
+const defaultSender: HttpSender = (url, init) => fetch(url, init) as unknown as ReturnType<HttpSender>;
+
+/**
+ * SMS egress via Twilio, using the CALLER'S OWN credentials (resolved per scope at send time).
+ * Fail-closed: no scope or no configured creds ⇒ FAILED/NOT_CONFIGURED, nothing sent. A Twilio
+ * API error is surfaced as FAILED (never thrown), per the provider doctrine.
+ */
+export class TwilioSmsProvider implements CapabilityProvider {
+  readonly name = 'twilio-sms';
+  readonly channelTypes = ['SMS'];
+  readonly capabilities = { canSend: true, maxPayloadBytes: 1600 };
+
+  constructor(
+    private readonly resolve: TwilioCredResolver,
+    private readonly http: HttpSender = defaultSender,
+  ) {}
+
+  async send(req: CapabilityRequest): Promise<ProviderResult> {
+    const started = Date.now();
+    if (!req.scopeId) return { providerRef: 'unconfigured', outcome: 'FAILED', errorCode: 'NOT_CONFIGURED' };
+
+    const creds = await this.resolve(req.scopeId).catch(() => null);
+    if (!creds) return { providerRef: 'unconfigured', outcome: 'FAILED', errorCode: 'NOT_CONFIGURED' };
+
+    const body = new URLSearchParams({
+      To: req.target,
+      From: creds.fromNumber,
+      Body: String(req.payload.text ?? req.payload.body ?? ''),
+    }).toString();
+
+    try {
+      const res = await this.http(`https://api.twilio.com/2010-04-01/Accounts/${creds.accountSid}/Messages.json`, {
+        method: 'POST',
+        headers: {
+          authorization: `Basic ${Buffer.from(`${creds.accountSid}:${creds.authToken}`).toString('base64')}`,
+          'content-type': 'application/x-www-form-urlencoded',
+        },
+        body,
+      });
+      const latencyMs = Date.now() - started;
+      const payload = (await res.json().catch(() => ({}))) as { sid?: string; code?: number; message?: string };
+      if (!res.ok) {
+        return { providerRef: `twilio-${res.status}`, outcome: 'FAILED', errorCode: payload.code ? `TWILIO_${payload.code}` : `HTTP_${res.status}`, latencyMs };
+      }
+      return { providerRef: payload.sid ?? 'twilio-sent', outcome: 'SENT', latencyMs };
+    } catch (err) {
+      return { providerRef: 'twilio-error', outcome: 'FAILED', errorCode: (err as Error).message.slice(0, 60), latencyMs: Date.now() - started };
+    }
+  }
+}
diff --git a/packages/iios-service/src/messaging/message.service.ts b/packages/iios-service/src/messaging/message.service.ts
index f1699d6..450aba8 100644
--- a/packages/iios-service/src/messaging/message.service.ts
+++ b/packages/iios-service/src/messaging/message.service.ts
@@ -114,10 +114,18 @@ export class MessageService {
     const actor = await this.actors.resolveActor(thread.scopeId, principal);
     const alreadyMember =
       (await this.prisma.iiosThreadParticipant.findUnique({ where: { threadId_actorId: { threadId, actorId: actor.id } } })) !== null;
-    // Join is governed ONLY for threads that opted into a membership model (chat dm/group);
-    // support/inbox/generic threads (no membership attr) keep open-join, unchanged.
-    const membership = (thread.metadata as { membership?: string } | null)?.membership;
-    await decideOrThrow(this.ports, { action: 'iios.thread.join', threadId, scopeId: thread.scopeId, membership, alreadyMember });
+    // Join is governed ONLY for threads that opted into a membership model (chat dm/group/channel);
+    // support/inbox/generic threads (no membership attr) keep open-join, unchanged. A PUBLIC channel
+    // is the one membership type that also allows open self-join (policy reads `visibility`).
+    const bag = (thread.metadata as { membership?: string; visibility?: string } | null) ?? {};
+    await decideOrThrow(this.ports, {
+      action: 'iios.thread.join',
+      threadId,
+      scopeId: thread.scopeId,
+      membership: bag.membership,
+      visibility: bag.visibility,
+      alreadyMember,
+    });
     await this.actors.ensureParticipant(threadId, actor.id);
     return { threadId, status: thread.status, history: await this.history(threadId) };
   }
@@ -228,6 +236,60 @@ export class MessageService {
     }));
   }
 
+  /**
+   * Scope-wide thread discovery — the ONE generic primitive channels need beyond dm/group.
+   * Unlike listThreads (membership-scoped), this returns threads in the caller's scope matching an
+   * opaque metadata filter (e.g. {membership:'channel', visibility:'public'}) REGARDLESS of whether
+   * the caller is a participant, each flagged `joined`. Governed by policy (fail-closed) + fenced to
+   * the caller's own scope. The kernel never interprets the filter keys.
+   */
+  async discoverThreads(
+    principal: MessagePrincipal,
+    filter?: { metadata?: Record<string, string> },
+  ): Promise<Array<{ threadId: string; subject: string | null; metadata: Record<string, unknown> | null; participantCount: number; joined: boolean }>> {
+    const scope = await this.actors.findScope(principal);
+    if (!scope) return [];
+    await decideOrThrow(this.ports, { action: 'iios.thread.discover', scopeId: scope.id });
+    const actor = await this.actors.resolveActor(scope.id, principal);
+
+    const inScope = await this.prisma.iiosThread.findMany({ where: { scopeId: scope.id } });
+    const metaFilter = filter?.metadata;
+    const matched = metaFilter
+      ? inScope.filter((t) => {
+          const bag = (t.metadata as Record<string, unknown> | null) ?? {};
+          return Object.entries(metaFilter).every(([k, v]) => bag[k] === v);
+        })
+      : inScope;
+    if (matched.length === 0) return [];
+
+    const ids = matched.map((t) => t.id);
+    const parts = await this.prisma.iiosThreadParticipant.groupBy({ by: ['threadId'], where: { threadId: { in: ids } }, _count: { actorId: true } });
+    const countBy = new Map(parts.map((p) => [p.threadId, p._count.actorId]));
+    const mine = await this.prisma.iiosThreadParticipant.findMany({ where: { threadId: { in: ids }, actorId: actor.id }, select: { threadId: true } });
+    const joinedSet = new Set(mine.map((m) => m.threadId));
+
+    return matched.map((t) => ({
+      threadId: t.id,
+      subject: t.subject,
+      metadata: (t.metadata as Record<string, unknown> | null) ?? null,
+      participantCount: countBy.get(t.id) ?? 0,
+      joined: joinedSet.has(t.id),
+    }));
+  }
+
+  /** Self-leave: remove the caller's own participant row. Governed (a member may always leave). */
+  async leaveThread(threadId: string, principal: MessagePrincipal): Promise<{ threadId: string; participantCount: number }> {
+    const thread = await this.prisma.iiosThread.findUnique({ where: { id: threadId } });
+    if (!thread) throw new NotFoundException('thread not found');
+    const actor = await this.actors.resolveActor(thread.scopeId, principal);
+    const callerP = await this.prisma.iiosThreadParticipant.findUnique({ where: { threadId_actorId: { threadId, actorId: actor.id } } });
+    const membership = (thread.metadata as { membership?: string } | null)?.membership;
+    await decideOrThrow(this.ports, { action: 'iios.thread.leave', threadId, scopeId: thread.scopeId, membership, callerRole: callerP?.participantRole });
+    await this.prisma.iiosThreadParticipant.deleteMany({ where: { threadId, actorId: actor.id } });
+    const participantCount = await this.prisma.iiosThreadParticipant.count({ where: { threadId } });
+    return { threadId, participantCount };
+  }
+
   /** Toggle the caller's per-thread notification mute flag. */
   async muteThread(threadId: string, principal: MessagePrincipal, muted: boolean): Promise<{ threadId: string; muted: boolean }> {
     const thread = await this.prisma.iiosThread.findUnique({ where: { id: threadId } });
diff --git a/packages/iios-service/src/messaging/message.spec.ts b/packages/iios-service/src/messaging/message.spec.ts
index 46101ee..9514ba8 100644
--- a/packages/iios-service/src/messaging/message.spec.ts
+++ b/packages/iios-service/src/messaging/message.spec.ts
@@ -154,6 +154,34 @@ describe('Governed membership + replies (v1.1, policy-enforced)', () => {
     expect((await s.openThread(threadId, bob)).threadId).toBe(threadId);
   });
 
+  it('channels: a PUBLIC channel allows open self-join; a PRIVATE one does not', async () => {
+    const s = gov();
+    const { threadId: pub } = await s.openThread(null, alice, { membership: 'channel', metadata: { visibility: 'public' }, subject: 'general', creatorRole: 'ADMIN' });
+    expect((await s.openThread(pub, bob)).threadId).toBe(pub); // bob self-joins a public channel
+
+    const { threadId: priv } = await s.openThread(null, alice, { membership: 'channel', metadata: { visibility: 'private' }, subject: 'deals', creatorRole: 'ADMIN' });
+    await expect(s.openThread(priv, bob)).rejects.toBeInstanceOf(PolicyDeniedError); // private = invite-only
+  });
+
+  it('discoverThreads browses same-scope channels with a joined flag; leave removes me', async () => {
+    const s = gov();
+    const { threadId: gen } = await s.openThread(null, alice, { membership: 'channel', metadata: { visibility: 'public' }, subject: 'general', creatorRole: 'ADMIN' });
+    await s.openThread(null, alice, { membership: 'group', creatorRole: 'ADMIN' }); // a group must NOT appear in a channel browse
+
+    // bob (non-member, same scope) discovers the public channel as not-joined.
+    const seen = await s.discoverThreads(bob, { metadata: { membership: 'channel', visibility: 'public' } });
+    expect(seen.map((t) => t.threadId)).toEqual([gen]);
+    expect(seen[0]!.joined).toBe(false);
+    // alice (member) sees it joined.
+    expect((await s.discoverThreads(alice, { metadata: { membership: 'channel', visibility: 'public' } }))[0]!.joined).toBe(true);
+
+    // bob joins, appears in his list, then leaves.
+    await s.openThread(gen, bob);
+    expect((await s.listThreads(bob)).map((t) => t.threadId)).toContain(gen);
+    await s.leaveThread(gen, bob);
+    expect((await s.listThreads(bob)).map((t) => t.threadId)).not.toContain(gen);
+  });
+
   it('listThreads returns the caller’s threads with membership, count, last message + unread', async () => {
     const s = gov();
     const { threadId } = await s.openThread(null, alice, { membership: 'group', creatorRole: 'ADMIN' });
diff --git a/packages/iios-service/src/platform/dev-opa.port.spec.ts b/packages/iios-service/src/platform/dev-opa.port.spec.ts
index f2741b6..614d5bb 100644
--- a/packages/iios-service/src/platform/dev-opa.port.spec.ts
+++ b/packages/iios-service/src/platform/dev-opa.port.spec.ts
@@ -62,6 +62,20 @@ describe('DevOpaPort (dev policy plane — membership rules)', () => {
     expect(big.obligations[0]?.reason).toMatch(/too large/);
   });
 
+  it('a PUBLIC channel allows open self-join; private channel and group do not', async () => {
+    expect((await opa.decide({ action: 'iios.thread.join', membership: 'channel', visibility: 'public', alreadyMember: false })).allow).toBe(true);
+    const priv = await opa.decide({ action: 'iios.thread.join', membership: 'channel', visibility: 'private', alreadyMember: false });
+    expect(priv.allow).toBe(false);
+    expect((await opa.decide({ action: 'iios.thread.join', membership: 'group', alreadyMember: false })).allow).toBe(false);
+    // an existing member of a private channel can still (re)open it
+    expect((await opa.decide({ action: 'iios.thread.join', membership: 'channel', visibility: 'private', alreadyMember: true })).allow).toBe(true);
+  });
+
+  it('discover and leave are allowed (scope fence / member-implied)', async () => {
+    expect((await opa.decide({ action: 'iios.thread.discover' })).allow).toBe(true);
+    expect((await opa.decide({ action: 'iios.thread.leave', membership: 'channel' })).allow).toBe(true);
+  });
+
   it('self-join is governed only on membership threads', async () => {
     // generic / support thread (no membership attr) → open join, unchanged
     expect((await opa.decide({ action: 'iios.thread.join', alreadyMember: false })).allow).toBe(true);
diff --git a/packages/iios-service/src/platform/dev-opa.port.ts b/packages/iios-service/src/platform/dev-opa.port.ts
index 91f129f..c96c33a 100644
--- a/packages/iios-service/src/platform/dev-opa.port.ts
+++ b/packages/iios-service/src/platform/dev-opa.port.ts
@@ -9,7 +9,8 @@ import type { PolicyDecision } from '@insignia/iios-contracts';
  */
 export interface OpaInput {
   action?: string;
-  membership?: string; // app-set generic thread attribute: 'dm' | 'group'
+  membership?: string; // app-set generic thread attribute: 'dm' | 'group' | 'channel'
+  visibility?: string; // 'public' | 'private' (channels)
   participantCount?: number;
   callerRole?: string; // 'MEMBER' | 'ADMIN'
   alreadyMember?: boolean;
@@ -55,12 +56,21 @@ export class DevOpaPort {
         return allow();
       }
       case 'iios.thread.join': {
-        // Only threads that opted into a membership model (chat dm/group) are governed;
-        // generic/support threads (no membership attr) keep open-join. For a governed
-        // thread, new members must be added first (governed add-participant).
+        // Generic/support threads (no membership attr) keep open-join. A PUBLIC channel is the one
+        // membership type that also allows open self-join. dm/group/private-channel are closed:
+        // new members must be added first (governed add-participant).
         if (!i.membership) return allow();
+        if (i.membership === 'channel' && i.visibility === 'public') return allow();
         return i.alreadyMember ? allow() : deny('you are not a member of this thread');
       }
+      case 'iios.thread.discover': {
+        // Browsing discoverable threads — the query fences to the caller's own scope, so allow.
+        return allow();
+      }
+      case 'iios.thread.leave': {
+        // Anyone may leave a thread they're in. (A membership thread implies the caller is a member.)
+        return allow();
+      }
       case 'iios.interaction.annotate': {
         // Annotating (e.g. reacting to) a message requires being a participant of its thread.
         return i.isMember ? allow() : deny('you are not a member of this thread');
diff --git a/packages/iios-service/src/threads/threads.controller.ts b/packages/iios-service/src/threads/threads.controller.ts
index afc32e5..5a8d023 100644
--- a/packages/iios-service/src/threads/threads.controller.ts
+++ b/packages/iios-service/src/threads/threads.controller.ts
@@ -44,6 +44,18 @@ export class ThreadsController {
     return this.messages.listMyAnnotated(this.principal(auth), type);
   }
 
+  /**
+   * Discover threads across the caller's scope (not just ones they're in) matching an opaque
+   * metadata filter — e.g. `?metadata[membership]=channel&metadata[visibility]=public` to browse
+   * public channels. Each result is flagged `joined`. Declared before `:id` routes so the static
+   * "discover" segment wins.
+   */
+  @Get('discover')
+  async discover(@Headers('authorization') auth?: string, @Query('metadata') metadata?: Record<string, string>) {
+    const metaFilter = metadata && typeof metadata === 'object' ? metadata : undefined;
+    return this.messages.discoverThreads(this.principal(auth), metaFilter ? { metadata: metaFilter } : undefined);
+  }
+
   /** Create a thread; `membership`/`creatorRole`/`subject`/`metadata` are opaque, app-supplied attributes the kernel stores but never interprets. */
   @Post()
   @HttpCode(201)
@@ -79,6 +91,13 @@ export class ThreadsController {
     return this.messages.renameThread(id, this.principal(auth), body.subject);
   }
 
+  /** Self-leave: remove the caller from a thread (e.g. leave a channel). */
+  @Delete(':id/me')
+  @HttpCode(200)
+  async leave(@Param('id') id: string, @Headers('authorization') auth?: string) {
+    return this.messages.leaveThread(id, this.principal(auth));
+  }
+
   @Get(':id/messages')
   async listMessages(@Param('id') id: string) {
     return this.threads.getMessages(id);
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 251f3b0..4aac1a1 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -16,7 +16,7 @@ importers:
         version: 5.9.3
       vitest:
         specifier: ^3.0.5
-        version: 3.2.6(@types/node@26.0.1)(jiti@2.7.0)(terser@5.48.0)
+        version: 3.2.6(@types/node@26.0.1)(jiti@2.7.0)(jsdom@26.1.0)(terser@5.48.0)
 
   apps/adapter-inspector:
     dependencies:
@@ -326,6 +326,42 @@ importers:
         specifier: ^5.7.3
         version: 5.9.3
 
+  packages/iios-messaging-ui:
+    devDependencies:
+      '@insignia/iios-kernel-client':
+        specifier: workspace:*
+        version: link:../iios-kernel-client
+      '@testing-library/dom':
+        specifier: ^10.4.0
+        version: 10.4.1
+      '@testing-library/react':
+        specifier: ^16.1.0
+        version: 16.3.2(@testing-library/dom@10.4.1)(@types/react-dom@19.2.3(@types/react@19.2.17))(@types/react@19.2.17)(react-dom@19.2.7(react@19.2.7))(react@19.2.7)
+      '@types/react':
+        specifier: ^19.0.0
+        version: 19.2.17
+      '@types/react-dom':
+        specifier: ^19.0.0
+        version: 19.2.3(@types/react@19.2.17)
+      jsdom:
+        specifier: ^26.0.0
+        version: 26.1.0
+      react:
+        specifier: ^19.0.0
+        version: 19.2.7
+      react-dom:
+        specifier: ^19.0.0
+        version: 19.2.7(react@19.2.7)
+      tsup:
+        specifier: ^8.3.5
+        version: 8.5.1(jiti@2.7.0)(postcss@8.5.16)(typescript@5.9.3)
+      typescript:
+        specifier: ^5.7.3
+        version: 5.9.3
+      vitest:
+        specifier: ^3.0.5
+        version: 3.2.6(@types/node@26.0.1)(jiti@2.7.0)(jsdom@26.1.0)(terser@5.48.0)
+
   packages/iios-service:
     dependencies:
       '@aws-sdk/client-s3':
@@ -490,6 +526,9 @@ packages:
     resolution: {integrity: sha512-/PZmyAlb2NGWPikRRuiWLdfHQd8Wrx6lX4HqvTcaDhlU43M3T0ud4PH2T3QDp7BzHYY92xtD8iPxX2asg67G1A==}
     engines: {node: ^18.19.1 || ^20.11.1 || >=22.0.0, npm: ^6.11.0 || ^7.5.6 || >=8.0.0, yarn: '>= 1.13.0'}
 
+  '@asamuzakjp/css-color@3.2.0':
+    resolution: {integrity: sha512-K1A6z8tS3XsmCMM86xoWdn7Fkdn9m6RSVtocUrJYIwZnFVkng/PvkEoWtOWmP+Scc6saYWHWZYbndEEXxl24jw==}
+
   '@aws-sdk/checksums@3.1000.18':
     resolution: {integrity: sha512-IImkbEyXdV6/uaF5r6Wkk+8718mQw1ll83j0a4a30R3JM/rHVFdWAiT4jtJpFjJiIwM/oJ6SxIxr0z2TaQUGqw==}
     engines: {node: '>=20.0.0'}
@@ -633,6 +672,10 @@ packages:
     peerDependencies:
       '@babel/core': ^7.0.0-0
 
+  '@babel/runtime@7.29.7':
+    resolution: {integrity: sha512-Nq8OhGWiZIZGV6hLHoyAKLLcJihP/xFeBMGJoUrxTX2psI8dCifzLhZISFb+VWS3wFMRDmCGw5R+dOySCqPLhw==}
+    engines: {node: '>=6.9.0'}
+
   '@babel/template@7.29.7':
     resolution: {integrity: sha512-puq+Gf35oI24FeN11LkoUQFqv9uwNeWpxXZi/Ji3rRIoKAzKnxRaZ+Gkj0vKS9ZCiTESfng1N9LyOyXvo+m+Gg==}
     engines: {node: '>=6.9.0'}
@@ -652,6 +695,34 @@ packages:
     resolution: {integrity: sha512-ooWCrlZP11i8GImSjTHYHLkvFDP48nS4+204nGb1RiX/WXYHmJA2III9/e2DWVabCESdW7hBAEzHRqUn9OUVvQ==}
     engines: {node: '>=0.1.90'}
 
+  '@csstools/color-helpers@5.1.0':
+    resolution: {integrity: sha512-S11EXWJyy0Mz5SYvRmY8nJYTFFd1LCNV+7cXyAgQtOOuzb4EsgfqDufL+9esx72/eLhsRdGZwaldu/h+E4t4BA==}
+    engines: {node: '>=18'}
+
+  '@csstools/css-calc@2.1.4':
+    resolution: {integrity: sha512-3N8oaj+0juUw/1H3YwmDDJXCgTB1gKU6Hc/bB502u9zR0q2vd786XJH9QfrKIEgFlZmhZiq6epXl4rHqhzsIgQ==}
+    engines: {node: '>=18'}
+    peerDependencies:
+      '@csstools/css-parser-algorithms': ^3.0.5
+      '@csstools/css-tokenizer': ^3.0.4
+
+  '@csstools/css-color-parser@3.1.0':
+    resolution: {integrity: sha512-nbtKwh3a6xNVIp/VRuXV64yTKnb1IjTAEEh3irzS+HkKjAOYLTGNb9pmVNntZ8iVBHcWDA2Dof0QtPgFI1BaTA==}
+    engines: {node: '>=18'}
+    peerDependencies:
+      '@csstools/css-parser-algorithms': ^3.0.5
+      '@csstools/css-tokenizer': ^3.0.4
+
+  '@csstools/css-parser-algorithms@3.0.5':
+    resolution: {integrity: sha512-DaDeUkXZKjdGhgYaHNJTV9pV7Y9B3b644jCLs9Upc3VeNGg6LWARAT6O+Q+/COo+2gg/bM5rhpMAtf70WqfBdQ==}
+    engines: {node: '>=18'}
+    peerDependencies:
+      '@csstools/css-tokenizer': ^3.0.4
+
+  '@csstools/css-tokenizer@3.0.4':
+    resolution: {integrity: sha512-Vd/9EVDiu6PPJt9yAh6roZP6El1xHrdvIVGjyBsHR0RYwNHgL7FJPyIIW4fANJNG6FtyZfvlRPpFI4ZM/lubvw==}
+    engines: {node: '>=18'}
+
   '@esbuild/aix-ppc64@0.25.12':
     resolution: {integrity: sha512-Hhmwd6CInZ3dwpuGTF8fJG6yoWmsToE+vYgD4nytZVxcu1ulHpUQRAB1UJ8+N1Am3Mz4+xOByoQoSZf4D+CpkA==}
     engines: {node: '>=18'}
@@ -1561,6 +1632,25 @@ packages:
   '@standard-schema/spec@1.1.0':
     resolution: {integrity: sha512-l2aFy5jALhniG5HgqrD6jXLi/rUWrKvqN/qJx6yoJsgKhblVd+iqqU4RCXavm/jPityDo5TCvKMnpjKnOriy0w==}
 
+  '@testing-library/dom@10.4.1':
+    resolution: {integrity: sha512-o4PXJQidqJl82ckFaXUeoAW+XysPLauYI43Abki5hABd853iMhitooc6znOnczgbTYmEP6U6/y1ZyKAIsvMKGg==}
+    engines: {node: '>=18'}
+
+  '@testing-library/react@16.3.2':
+    resolution: {integrity: sha512-XU5/SytQM+ykqMnAnvB2umaJNIOsLF3PVv//1Ew4CTcpz0/BRyy/af40qqrt7SjKpDdT1saBMc42CUok5gaw+g==}
+    engines: {node: '>=18'}
+    peerDependencies:
+      '@testing-library/dom': ^10.0.0
+      '@types/react': ^18.0.0 || ^19.0.0
+      '@types/react-dom': ^18.0.0 || ^19.0.0
+      react: ^18.0.0 || ^19.0.0
+      react-dom: ^18.0.0 || ^19.0.0
+    peerDependenciesMeta:
+      '@types/react':
+        optional: true
+      '@types/react-dom':
+        optional: true
+
   '@tokenizer/inflate@0.4.1':
     resolution: {integrity: sha512-2mAv+8pkG6GIZiF1kNg1jAjh27IDxEPKwdGul3snfztFerfPGI1LjDezZp3i7BElXompqEtPmoPx6c2wgtWsOA==}
     engines: {node: '>=18'}
@@ -1568,6 +1658,9 @@ packages:
   '@tokenizer/token@0.3.0':
     resolution: {integrity: sha512-OvjF+z51L3ov0OyAU0duzsYuvO01PH7x4t6DJx+guahgTnBHkhJdG7soQeTSFLWN3efnHyibZ4Z8l2EuWwJN3A==}
 
+  '@types/aria-query@5.0.4':
+    resolution: {integrity: sha512-rfT93uj5s0PRL7EzccGMs3brplhcrghnDoV26NqKhCAS1hVo+WdNsPvE/yb6ilfr5hi2MEk6d5EWJTKdxg8jVw==}
+
   '@types/babel__core@7.20.5':
     resolution: {integrity: sha512-qoQprZvz5wQFJwMDqeseRXWv3rqMvhgpbXFfVyWhbx9X47POIA6i/+dXefEmZKoAgOaTdaIgNSMqMIU61yRyzA==}
 
@@ -1813,6 +1906,10 @@ packages:
     resolution: {integrity: sha512-zbB9rCJAT1rbjiVDb2hqKFHNYLxgtk8NURxZ3IZwD3F6NtxbXZQCnnSi1Lkx+IDohdPlFp222wVALIheZJQSEg==}
     engines: {node: '>=8'}
 
+  ansi-styles@5.2.0:
+    resolution: {integrity: sha512-Cxwpt2SfTzTtXcfOlzGEee8O+c+MmUgGrNiBcXnuWxuFJHe6a5Hz7qwhwe5OgaSYI0IJvkLqWX1ASG+cJOkEiA==}
+    engines: {node: '>=10'}
+
   ansis@4.2.0:
     resolution: {integrity: sha512-HqZ5rWlFjGiV0tDm3UxxgNRqsOTniqoKZu0pIAfh7TZQMGuZK+hH0drySty0si0QXj1ieop4+SkSfPZBPPkHig==}
     engines: {node: '>=14'}
@@ -1826,6 +1923,9 @@ packages:
   argparse@2.0.1:
     resolution: {integrity: sha512-8+9WqebbFzpX9OR+Wa6O29asIogeRMzcGtAINdpMHHyAg10f05aSFVBbcEqGf/PXw1EjAZ+q2/bEBg3DvurK3Q==}
 
+  aria-query@5.3.0:
+    resolution: {integrity: sha512-b0P0sZPKtyu8HkeRAfCq0IfURZK+SuwMjY1UXGBU27wpAiTwQAIlq56IbIO+ytk/JjS1fMR14ee5WBBfKi5J6A==}
+
   array-timsort@1.0.3:
     resolution: {integrity: sha512-/+3GRL7dDAGEfM6TseQk/U+mi18TU2Ms9I3UlLdUMhz2hbvGNTKdj9xniwXfUqgYhHxRx0+8UnKkvlNwVU+cWQ==}
 
@@ -2060,9 +2160,17 @@ packages:
       typescript:
         optional: true
 
+  cssstyle@4.6.0:
+    resolution: {integrity: sha512-2z+rWdzbbSZv6/rhtvzvqeZQHrBaqgogqt85sqFNbabZOuFbCVFb8kPeEtZjiKkbrm395irpNKiYeFeLiQnFPg==}
+    engines: {node: '>=18'}
+
   csstype@3.2.3:
     resolution: {integrity: sha512-z1HGKcYy2xA8AGQfwrn0PAy+PB7X/GSj3UVJW9qKyn43xWa+gl5nXmU4qqLMRzWVLFC8KusUX8T/0kCiOYpAIQ==}
 
+  data-urls@5.0.0:
+    resolution: {integrity: sha512-ZYP5VBHshaDAiVZxjbRVcFJpc+4xGgT0bK3vzy1HLN8jTO975HEbuYzZJcHoQEY5K1a0z8YayJkyVETa08eNTg==}
+    engines: {node: '>=18'}
+
   debug@4.3.7:
     resolution: {integrity: sha512-Er2nc/H7RrMXZBFCEim6TCmMk02Z8vLC2Rbi1KEBggpo0fS6l0S1nnapwmIi3yW/+GOJap1Krg4w0Hg80oCqgQ==}
     engines: {node: '>=6.0'}
@@ -2081,6 +2189,9 @@ packages:
       supports-color:
         optional: true
 
+  decimal.js@10.6.0:
+    resolution: {integrity: sha512-YpgQiITW3JXGntzdUmyUR1V812Hn8T1YVXhCu+wO3OpS4eU9l4YdD3qjyiKdV6mvV29zapkMeD390UVEf2lkUg==}
+
   deep-eql@5.0.2:
     resolution: {integrity: sha512-h5k/5U50IJJFpzfL6nO9jaaumfjO/f2NjK/oYB2Djzm4p9L+3T9qWpZqZ2hAbLPuuYq9wrU08WQyBTL5GbPk5Q==}
     engines: {node: '>=6'}
@@ -2107,9 +2218,16 @@ packages:
     resolution: {integrity: sha512-g7nH6P6dyDioJogAAGprGpCtVImJhpPk/roCzdb3fIh61/s/nPsfR6onyMwkCAR/OlC3yBC0lESvUoQEAssIrw==}
     engines: {node: '>= 0.8'}
 
+  dequal@2.0.3:
+    resolution: {integrity: sha512-0je+qPKHEMohvfRTCEo3CrPG6cAzAYgmzKyxRiYSSDkS6eGJdyVJm7WaYA5ECaAD9wLB2T4EEeymA5aFVcYXCA==}
+    engines: {node: '>=6'}
+
   destr@2.0.5:
     resolution: {integrity: sha512-ugFTXCtDZunbzasqBxrK93Ik/DRYsO6S/fedkWEMKqt04xZ4csmnmwGDBAb07QWNaGMAmnTIemsYZCksjATwsA==}
 
+  dom-accessibility-api@0.5.16:
+    resolution: {integrity: sha512-X7BJ2yElsnOJ30pZF4uIIDfBEVgF4XEBxL9Bxhy6dnrm5hkzqmsWHGTiHqRiITNhMyFLyAiWndIJP7Z1NTteDg==}
+
   dotenv@16.6.1:
     resolution: {integrity: sha512-uBq4egWHTcTt33a72vpSG0z3HnPuIl6NqYcTrKEg2azoEyl2hpW0zqlxysq2pK9HlDIHyHyakeYaYnSAwd8bow==}
     engines: {node: '>=12'}
@@ -2156,6 +2274,10 @@ packages:
     resolution: {integrity: sha512-7DdUaTjmNwMcH2gLr1qycesKII3BK4RLy/mdAb7x10Lq7bR4aNKHt1BR1ZALSv0rPM/hF5wYF0PhGop/rJm8vw==}
     engines: {node: '>=10.13.0'}
 
+  entities@6.0.1:
+    resolution: {integrity: sha512-aN97NXWF6AWBTahfVOIrB/NShkzi5H7F9r1s9mD3cDj4Ko5f2qhhVoYMibXF7GlLveb/D2ioWay8lxI97Ven3g==}
+    engines: {node: '>=0.12'}
+
   error-ex@1.3.4:
     resolution: {integrity: sha512-sqQamAnR14VgCr1A618A3sGrygcpK+HEbenA/HiEAkkUwcZIIB/tgWqHFxWgOyDh4nB4JCRimh79dR5Ywc9MDQ==}
 
@@ -2355,10 +2477,18 @@ packages:
     resolution: {integrity: sha512-T2UbfbBEF32wiepXIsMlTW9+dDYC6wMh/t/vYA4tuOMKqWz/n3vr1NFSxQiyP+zk2mXsoMA/i/7qV6LKut1t1A==}
     engines: {node: '>= 0.4'}
 
+  html-encoding-sniffer@4.0.0:
+    resolution: {integrity: sha512-Y22oTqIU4uuPgEemfz7NDJz6OeKf12Lsu+QC+s3BVpda64lTiMYCyGwg5ki4vFxkMwQdeZDl2adZoqUgdFuTgQ==}
+    engines: {node: '>=18'}
+
   http-errors@2.0.1:
     resolution: {integrity: sha512-4FbRdAX+bSdmo4AUFuS0WNiPz8NgFt+r8ThgNWmlrjQjt1Q7ZR9+zTlce2859x4KSXrwIsaeTqDoKQmtP8pLmQ==}
     engines: {node: '>= 0.8'}
 
+  http-proxy-agent@7.0.2:
+    resolution: {integrity: sha512-T1gkAiYYDWYx3V5Bmyu7HcfcvL7mUrTWiM6yOfa3PIphViJ/gFPbvidQ+veqSOHci/PxBcDabeUNCzpOODJZig==}
+    engines: {node: '>= 14'}
+
   http_ece@1.2.0:
     resolution: {integrity: sha512-JrF8SSLVmcvc5NducxgyOrKXe3EsyHMgBFgSaIUGmArKe+rwr0uphRkRXvwiom3I+fpIfoItveHrfudL8/rxuA==}
     engines: {node: '>=16'}
@@ -2367,6 +2497,10 @@ packages:
     resolution: {integrity: sha512-vK9P5/iUfdl95AI+JVyUuIcVtd4ofvtrOr3HNtM2yxC9bnMbEdp3x01OhQNnjb8IJYi38VlTE3mBXwcfvywuSw==}
     engines: {node: '>= 14'}
 
+  iconv-lite@0.6.3:
+    resolution: {integrity: sha512-4fCk79wshMdzMp2rH06qWrJE4iolqLhCUH+OiuIgU++RB0+94NlDL81atO7GX55uUKueo0txHNtvEyI6D7WdMw==}
+    engines: {node: '>=0.10.0'}
+
   iconv-lite@0.7.2:
     resolution: {integrity: sha512-im9DjEDQ55s9fL4EYzOAv0yMqmMBSZp6G0VvFyTMPKWxiSBHUj9NW/qqLmXUwXrrM7AvqSlTCfvqRb0cM8yYqw==}
     engines: {node: '>=0.10.0'}
@@ -2400,6 +2534,9 @@ packages:
     resolution: {integrity: sha512-2HvIEKRoqS62guEC+qBjpvRubdX910WCMuJTZ+I9yvqKU2/12eSL549HMwtabb4oupdj2sMP50k+XJfB/8JE6w==}
     engines: {node: '>=8'}
 
+  is-potential-custom-element-name@1.0.1:
+    resolution: {integrity: sha512-bCYeRA2rVibKZd+s2625gGnGF/t7DSqDs4dP7CrLA1m7jKWz6pps0LpYLJN8Q64HtmPKJ1hrN3nzPNKFEKOUiQ==}
+
   is-promise@4.0.0:
     resolution: {integrity: sha512-hvpoI6korhJMnej285dSg6nu1+e6uxs7zG3BYAm5byqDsgJNWwxzM6z6iZiAgQR4TJ30JmBTOwqZUw3WlyH3AQ==}
 
@@ -2436,6 +2573,15 @@ packages:
     resolution: {integrity: sha512-1td788aAnnZ5qs7V2QIRl1owjtYpbKt749Y3xauqQgwIIGF/xXWz1wMTEBx5O3LK3lXLVuqXPdPxj2BoFHaW9Q==}
     hasBin: true
 
+  jsdom@26.1.0:
+    resolution: {integrity: sha512-Cvc9WUhxSMEo4McES3P7oK3QaXldCfNWp7pl2NNeiIFlCoLr3kfq9kb1fxftiwk1FLV7CvpvDfonxtzUDeSOPg==}
+    engines: {node: '>=18'}
+    peerDependencies:
+      canvas: ^3.0.0
+    peerDependenciesMeta:
+      canvas:
+        optional: true
+
   jsesc@3.1.0:
     resolution: {integrity: sha512-/sM3dO2FOzXjKQhJuo0Q173wf2KOo8t4I8vHy6lF9poUp7bKT0/NHE8fPX23PwfhnykfqnC2xRxOnVw5XuGIaA==}
     engines: {node: '>=6'}
@@ -2534,6 +2680,9 @@ packages:
   loupe@3.2.1:
     resolution: {integrity: sha512-CdzqowRJCeLU72bHvWqwRBBlLcMEtIvGrlvef74kMnV2AolS9Y8xUv1I0U/MNAWMhBlKIoyuEgoJ0t/bbwHbLQ==}
 
+  lru-cache@10.4.3:
+    resolution: {integrity: sha512-JNAzZcXrCt42VGLuYz0zfAzDfAvJWW6AfYlDBQyDV5DClI2m5sAmK+OIO7s59XfsRsWHp02jAJrRadPRGTt6SQ==}
+
   lru-cache@11.5.1:
     resolution: {integrity: sha512-RPimw/7aMdv2oqRrxKwvZXcPfwBrn/JZ2xYcY9Hus/6LaS3VOAKVWKWgNLCFSiOm1ESXinjsDlidVU7JlnCN2A==}
     engines: {node: 20 || >=22}
@@ -2544,6 +2693,10 @@ packages:
   lru-memoizer@3.0.0:
     resolution: {integrity: sha512-m83w/cYXLdUIboKSPxzPAGfYnk+vqeDYXuoSrQRw1q+yVEd8IXhvMufN8Q5TIPe7e2jyX4SRNrDJI2Skw1yznQ==}
 
+  lz-string@1.5.0:
+    resolution: {integrity: sha512-h5bgJWpxJNswbU7qCrV0tIKQCaS3blPDrqKWx+QxzuzL1zGUzij9XCWLrSLsJPu5t+eWA/ycetzYAO5IOMcWAQ==}
+    hasBin: true
+
   magic-string@0.30.17:
     resolution: {integrity: sha512-sNPKHvyjVf7gyjwS4xGTaW/mCnF8wnjtifKBEhxfZ7E/S8tQ0rssrwGNn6q8JH/ohItJfSQp9mBtQYuTlH5QnA==}
 
@@ -2663,6 +2816,9 @@ packages:
   notepack.io@3.0.1:
     resolution: {integrity: sha512-TKC/8zH5pXIAMVQio2TvVDTtPRX+DJPHDqjRbxogtFiByHyzKmy96RA0JtCQJ+WouyyL4A10xomQzgbUT+1jCg==}
 
+  nwsapi@2.2.24:
+    resolution: {integrity: sha512-7YRhZ3jS45LwmSCT4b2sVFHt/WuovaktDU07QrtOBY2PXskss5a9jfmR9jptyumwXST+rFjrmppMY1KT/yn35A==}
+
   nypm@0.6.8:
     resolution: {integrity: sha512-Q9K4Diu6l5u6xJQogeFSs/zKtyMSgFKFtRQV+tHP4kL7KPm2grpBU0dFIwFaXwNxN0MtfKWc43VpCugAa+LPsw==}
     engines: {node: '>=18'}
@@ -2706,6 +2862,9 @@ packages:
     resolution: {integrity: sha512-ayCKvm/phCGxOkYRSCM82iDwct8/EonSEgCSxWxD7ve6jHggsFl4fZVQBPRNgQoKiuV/odhFrGzQXZwbifC8Rg==}
     engines: {node: '>=8'}
 
+  parse5@7.3.0:
+    resolution: {integrity: sha512-IInvU7fabl34qmi9gY8XOVxhYyMyuH2xUNpb2q8/Y+7552KlejkRvqvD19nMoUW/uQGGbqNpA6Tufu5FL5BZgw==}
+
   parseurl@1.3.3:
     resolution: {integrity: sha512-CiyeOxFT/JZyN5m0z9PfXw4SCBJ6Sygz1Dpl0wqjlhDEGGBP1GnsUVEL0p63hoG1fcj3fHynXi9NYO4nWOL+qQ==}
     engines: {node: '>= 0.8'}
@@ -2774,6 +2933,10 @@ packages:
     resolution: {integrity: sha512-vuwillviilfKZsg0VGj5R/YwwcHx4SLsIOI/7K6mQkWx+l5cUHTjj5g0AasTBcyXsbfTgrwsUNmVUb5xVwyPwg==}
     engines: {node: ^10 || ^12 || >=14}
 
+  pretty-format@27.5.1:
+    resolution: {integrity: sha512-Qb1gy5OrP5+zDf2Bvnzdl3jsTf1qXVMazbvCoKhtKqVs4/YK4ozX4gKQJJVyNe+cajNPn0KoC0MC3FUmaHWEmQ==}
+    engines: {node: ^10.13.0 || ^12.13.0 || ^14.15.0 || >=15.0.0}
+
   prisma@6.19.3:
     resolution: {integrity: sha512-++ZJ0ijLrDJF6hNB4t4uxg2br3fC4H9Yc9tcbjr2fcNFP3rh/SBNrAgjhsqBU4Ght8JPrVofG/ZkXfnSfnYsFg==}
     engines: {node: '>=18.18'}
@@ -2815,6 +2978,9 @@ packages:
     peerDependencies:
       react: ^19.2.7
 
+  react-is@17.0.2:
+    resolution: {integrity: sha512-w2GsyukL62IJnlaff/nRegPQR94C/XXamvMWmSHRJ4y7Ts/4ocGRmTHvOs8PSE6pB3dWOrD/nueuU5sduBsQ4w==}
+
   react-refresh@0.17.0:
     resolution: {integrity: sha512-z6F7K9bV85EfseRCp2bzrpyQ0Gkw1uLoCel9XBVWPg/TjRj94SkJzUTGfOa4bs7iJvBWtQG0Wq7wnI0syw3EBQ==}
     engines: {node: '>=0.10.0'}
@@ -2867,6 +3033,9 @@ packages:
     resolution: {integrity: sha512-nLTrUKm2UyiL7rlhapu/Zl45FwNgkZGaCpZbIHajDYgwlJCOzLSk+cIPAnsEqV955GjILJnKbdQC1nVPz+gAYQ==}
     engines: {node: '>= 18'}
 
+  rrweb-cssom@0.8.0:
+    resolution: {integrity: sha512-guoltQEx+9aMf2gDZ0s62EcV8lsXR+0w8915TC3ITdn2YueuNjdAYh/levpU9nFaoChh9RUS5ZdQMrKfVEN9tw==}
+
   rxjs@7.8.1:
     resolution: {integrity: sha512-AA3TVj+0A2iuIoQkWEK/tqFjBq2j+6PO6Y0zJcvzLAFhEFIO3HL0vls9hWLncZbAAbK0mar7oZ4V079I/qPMxg==}
 
@@ -2879,6 +3048,10 @@ packages:
   safer-buffer@2.1.2:
     resolution: {integrity: sha512-YZo3K82SD7Riyi0E1EQPojLz7kpepnSQI9IyPbHHg1XXXevb5dJI7tpyN2ADxGcQbHG7vcyRHk0cbwqcQriUtg==}
 
+  saxes@6.0.0:
+    resolution: {integrity: sha512-xAg7SOnEhrm5zI3puOOKyy1OMcMlIJZYNJY7xLBwSze0UjhPLnWfj2GF2EpT0jmzaJKIWKHLsaSSajf35bcYnA==}
+    engines: {node: '>=v12.22.7'}
+
   scheduler@0.27.0:
     resolution: {integrity: sha512-eNv+WrVbKu1f3vbYJT/xtiF5syA5HPIMtf9IgY/nKg0sWqzAUEvqY/xm7OcZc/qafLx/iO9FgOmeSAp4v5ti/Q==}
 
@@ -3026,6 +3199,9 @@ packages:
     resolution: {integrity: sha512-b19dMThMV4HVFynSAM1++gBHAbk2Tc/osgLIBZMKsyqh34jb2e8Os7T6ZW/Bt3pJFdBTd2JwAnAAEQV7rSNvcQ==}
     engines: {node: '>=0.10'}
 
+  symbol-tree@3.2.4:
+    resolution: {integrity: sha512-9QNk5KwDF+Bvz+PyObkmSYjI5ksVUYtjW7AU22r2NKcfLJcXp96hkDWU3+XndOsUb+AQ9QhfzfCT2O+CNWT5Tw==}
+
   tapable@2.3.3:
     resolution: {integrity: sha512-uxc/zpqFg6x7C8vOE7lh6Lbda8eEL9zmVm/PLeTPBRhh1xCgdWaQ+J1CUieGpIfm2HdtsUpRv+HshiasBMcc6A==}
     engines: {node: '>=6'}
@@ -3111,6 +3287,13 @@ packages:
     resolution: {integrity: sha512-azl+t0z7pw/z958Gy9svOTuzqIk6xq+NSheJzn5MMWtWTFywIacg2wUlzKFGtt3cthx0r2SxMK0yzJOR0IES7Q==}
     engines: {node: '>=14.0.0'}
 
+  tldts-core@6.1.86:
+    resolution: {integrity: sha512-Je6p7pkk+KMzMv2XXKmAE3McmolOQFdxkKw0R8EYNr7sELW46JqnNeTX8ybPiQgvg1ymCoF8LXs5fzFaZvJPTA==}
+
+  tldts@6.1.86:
+    resolution: {integrity: sha512-WMi/OQ2axVTf/ykqCQgXiIct+mSQDFdH2fkwhPwgEwvJ1kSzZRiinb0zF2Xb8u4+OqPChmyI6MEu4EezNJz+FQ==}
+    hasBin: true
+
   toidentifier@1.0.1:
     resolution: {integrity: sha512-o5sSPKEkg/DIQNmH43V0/uerLrpzVedkUh8tGNvaeXpfpuwjKenlSox/2O/BTlZUtEe+JG7s5YhEz608PlAHRA==}
     engines: {node: '>=0.6'}
@@ -3119,6 +3302,14 @@ packages:
     resolution: {integrity: sha512-dRXchy+C0IgK8WPC6xvCHFRIWYUbqqdEIKPaKo/AcTUNzwLTK6AH7RjdLWsEZcAN/TBdtfUw3PYEgPr5VPr6ww==}
     engines: {node: '>=14.16'}
 
+  tough-cookie@5.1.2:
+    resolution: {integrity: sha512-FVDYdxtnj0G6Qm/DhNPSb8Ju59ULcup3tuJxkFb5K8Bv2pUXILbf0xZWU8PX8Ov19OXljbUyveOFwRMwkXzO+A==}
+    engines: {node: '>=16'}
+
+  tr46@5.1.1:
+    resolution: {integrity: sha512-hdF5ZgjTqgAntKkklYw0R03MG2x/bSzTtkxmIRw/sTNV8YXsCJ1tfLAX23lhxhHJlEf3CRCOCGGWw3vI3GaSPw==}
+    engines: {node: '>=18'}
+
   tree-kill@1.2.2:
     resolution: {integrity: sha512-L0Orpi8qGpRG//Nd+H90vFB+3iHnue1zSSGmNOOCh1GLJ7rUKVwV2HvijphGQS2UmhUZewS9VgvxYIdgr+fG1A==}
     hasBin: true
@@ -3336,6 +3527,10 @@ packages:
       jsdom:
         optional: true
 
+  w3c-xmlserializer@5.0.0:
+    resolution: {integrity: sha512-o8qghlI8NZHU1lLPrpi2+Uq7abh4GGPpYANlalzWxyWteJOCsr/P+oPBA49TOLu5FTZO4d3F9MnWJfiMo4BkmA==}
+    engines: {node: '>=18'}
+
   watchpack@2.5.2:
     resolution: {integrity: sha512-6i/00NBjP4yGPs+caKSyRfpTF/8Torsu0MOW3mMzIbhgISFder8i7xbqgHlLMwJrdiN8ndBV3UA1/AfzPSr+jg==}
     engines: {node: '>=10.13.0'}
@@ -3348,6 +3543,10 @@ packages:
     engines: {node: '>= 16'}
     hasBin: true
 
+  webidl-conversions@7.0.0:
+    resolution: {integrity: sha512-VwddBukDzu71offAQR975unBIGqfKZpM+8ZX6ySk8nYhVoo5CYaZyzt3YBvYtRtO+aoGlqxPg/B87NGVZ/fu6g==}
+    engines: {node: '>=12'}
+
   webpack-node-externals@3.0.0:
     resolution: {integrity: sha512-LnL6Z3GGDPht/AigwRh2dvL9PQPFQ8skEpVrWZXLWBYmqcaojHNN0onvHzie6rq7EWKrrBfPYqNEzTJgiwEQDQ==}
     engines: {node: '>=6'}
@@ -3366,6 +3565,19 @@ packages:
       webpack-cli:
         optional: true
 
+  whatwg-encoding@3.1.1:
+    resolution: {integrity: sha512-6qN4hJdMwfYBtE3YBTTHhoeuUrDBPZmbQaxWAqSALV/MeEnR5z1xd8UKud2RAkFoPkmB+hli1TZSnyi84xz1vQ==}
+    engines: {node: '>=18'}
+    deprecated: Use @exodus/bytes instead for a more spec-conformant and faster implementation
+
+  whatwg-mimetype@4.0.0:
+    resolution: {integrity: sha512-QaKxh0eNIi2mE9p2vEdzfagOKHCcj1pJ56EEHGQOVxp8r9/iszLUUV7v89x9O1p/T+NlTM5W7jW6+cz4Fq1YVg==}
+    engines: {node: '>=18'}
+
+  whatwg-url@14.2.0:
+    resolution: {integrity: sha512-De72GdQZzNTUBBChsXueQUnPKDkg/5A5zp7pFDuQAj5UFoENpiACU0wlCvzpAGnTkj++ihpKwKyYewn/XNUbKw==}
+    engines: {node: '>=18'}
+
   why-is-node-running@2.3.0:
     resolution: {integrity: sha512-hUrmaWBdVDcxvYqnyh09zunKzROWjbZTiNy8dBEjkS7ehEDQibXJ7XvlmtbwuTclUiIyN+CyXQD4Vmko8fNm8w==}
     engines: {node: '>=8'}
@@ -3393,6 +3605,13 @@ packages:
       utf-8-validate:
         optional: true
 
+  xml-name-validator@5.0.0:
+    resolution: {integrity: sha512-EvGK8EJ3DhaHfbRlETOWAS5pO9MZITeauHKJyb8wyajUfQUenkIg2MvLDTZ4T/TgIcm3HU0TFBgWWboAZ30UHg==}
+    engines: {node: '>=18'}
+
+  xmlchars@2.2.0:
+    resolution: {integrity: sha512-JZnDKK8B0RCDw84FNdDAIpZK+JuJw+s7Lz8nksI7SIuU3UXJJslUthsi+uWBUYOwPFwW7W7PRLRfUKpxjtjFCw==}
+
   xmlhttprequest-ssl@2.1.2:
     resolution: {integrity: sha512-TEU+nJVUUnA4CYJFLvK5X9AOeH4KvDvhIfm0vV1GaQRtchnG0hgK5p8hw/xjv8cunWYCsiPCSDzObPyhEwq3KQ==}
     engines: {node: '>=0.4.0'}
@@ -3464,6 +3683,14 @@ snapshots:
     transitivePeerDependencies:
       - chokidar
 
+  '@asamuzakjp/css-color@3.2.0':
+    dependencies:
+      '@csstools/css-calc': 2.1.4(@csstools/css-parser-algorithms@3.0.5(@csstools/css-tokenizer@3.0.4))(@csstools/css-tokenizer@3.0.4)
+      '@csstools/css-color-parser': 3.1.0(@csstools/css-parser-algorithms@3.0.5(@csstools/css-tokenizer@3.0.4))(@csstools/css-tokenizer@3.0.4)
+      '@csstools/css-parser-algorithms': 3.0.5(@csstools/css-tokenizer@3.0.4)
+      '@csstools/css-tokenizer': 3.0.4
+      lru-cache: 10.4.3
+
   '@aws-sdk/checksums@3.1000.18':
     dependencies:
       '@aws-sdk/core': 3.975.3
@@ -3718,6 +3945,8 @@ snapshots:
       '@babel/core': 7.29.7
       '@babel/helper-plugin-utils': 7.29.7
 
+  '@babel/runtime@7.29.7': {}
+
   '@babel/template@7.29.7':
     dependencies:
       '@babel/code-frame': 7.29.7
@@ -3746,6 +3975,26 @@ snapshots:
   '@colors/colors@1.5.0':
     optional: true
 
+  '@csstools/color-helpers@5.1.0': {}
+
+  '@csstools/css-calc@2.1.4(@csstools/css-parser-algorithms@3.0.5(@csstools/css-tokenizer@3.0.4))(@csstools/css-tokenizer@3.0.4)':
+    dependencies:
+      '@csstools/css-parser-algorithms': 3.0.5(@csstools/css-tokenizer@3.0.4)
+      '@csstools/css-tokenizer': 3.0.4
+
+  '@csstools/css-color-parser@3.1.0(@csstools/css-parser-algorithms@3.0.5(@csstools/css-tokenizer@3.0.4))(@csstools/css-tokenizer@3.0.4)':
+    dependencies:
+      '@csstools/color-helpers': 5.1.0
+      '@csstools/css-calc': 2.1.4(@csstools/css-parser-algorithms@3.0.5(@csstools/css-tokenizer@3.0.4))(@csstools/css-tokenizer@3.0.4)
+      '@csstools/css-parser-algorithms': 3.0.5(@csstools/css-tokenizer@3.0.4)
+      '@csstools/css-tokenizer': 3.0.4
+
+  '@csstools/css-parser-algorithms@3.0.5(@csstools/css-tokenizer@3.0.4)':
+    dependencies:
+      '@csstools/css-tokenizer': 3.0.4
+
+  '@csstools/css-tokenizer@3.0.4': {}
+
   '@esbuild/aix-ppc64@0.25.12':
     optional: true
 
@@ -4418,6 +4667,27 @@ snapshots:
 
   '@standard-schema/spec@1.1.0': {}
 
+  '@testing-library/dom@10.4.1':
+    dependencies:
+      '@babel/code-frame': 7.29.7
+      '@babel/runtime': 7.29.7
+      '@types/aria-query': 5.0.4
+      aria-query: 5.3.0
+      dom-accessibility-api: 0.5.16
+      lz-string: 1.5.0
+      picocolors: 1.1.1
+      pretty-format: 27.5.1
+
+  '@testing-library/react@16.3.2(@testing-library/dom@10.4.1)(@types/react-dom@19.2.3(@types/react@19.2.17))(@types/react@19.2.17)(react-dom@19.2.7(react@19.2.7))(react@19.2.7)':
+    dependencies:
+      '@babel/runtime': 7.29.7
+      '@testing-library/dom': 10.4.1
+      react: 19.2.7
+      react-dom: 19.2.7(react@19.2.7)
+    optionalDependencies:
+      '@types/react': 19.2.17
+      '@types/react-dom': 19.2.3(@types/react@19.2.17)
+
   '@tokenizer/inflate@0.4.1':
     dependencies:
       debug: 4.4.3
@@ -4427,6 +4697,8 @@ snapshots:
 
   '@tokenizer/token@0.3.0': {}
 
+  '@types/aria-query@5.0.4': {}
+
   '@types/babel__core@7.20.5':
     dependencies:
       '@babel/parser': 7.29.7
@@ -4741,6 +5013,8 @@ snapshots:
     dependencies:
       color-convert: 2.0.1
 
+  ansi-styles@5.2.0: {}
+
   ansis@4.2.0: {}
 
   any-promise@1.3.0: {}
@@ -4749,6 +5023,10 @@ snapshots:
 
   argparse@2.0.1: {}
 
+  aria-query@5.3.0:
+    dependencies:
+      dequal: 2.0.3
+
   array-timsort@1.0.3: {}
 
   asn1.js@5.4.1:
@@ -4973,8 +5251,18 @@ snapshots:
     optionalDependencies:
       typescript: 5.9.3
 
+  cssstyle@4.6.0:
+    dependencies:
+      '@asamuzakjp/css-color': 3.2.0
+      rrweb-cssom: 0.8.0
+
   csstype@3.2.3: {}
 
+  data-urls@5.0.0:
+    dependencies:
+      whatwg-mimetype: 4.0.0
+      whatwg-url: 14.2.0
+
   debug@4.3.7:
     dependencies:
       ms: 2.1.3
@@ -4983,6 +5271,8 @@ snapshots:
     dependencies:
       ms: 2.1.3
 
+  decimal.js@10.6.0: {}
+
   deep-eql@5.0.2: {}
 
   deepmerge-ts@7.1.5: {}
@@ -4999,8 +5289,12 @@ snapshots:
 
   depd@2.0.0: {}
 
+  dequal@2.0.3: {}
+
   destr@2.0.5: {}
 
+  dom-accessibility-api@0.5.16: {}
+
   dotenv@16.6.1: {}
 
   dunder-proto@1.0.1:
@@ -5064,6 +5358,8 @@ snapshots:
       graceful-fs: 4.2.11
       tapable: 2.3.3
 
+  entities@6.0.1: {}
+
   error-ex@1.3.4:
     dependencies:
       is-arrayish: 0.2.1
@@ -5365,6 +5661,10 @@ snapshots:
     dependencies:
       function-bind: 1.1.2
 
+  html-encoding-sniffer@4.0.0:
+    dependencies:
+      whatwg-encoding: 3.1.1
+
   http-errors@2.0.1:
     dependencies:
       depd: 2.0.0
@@ -5373,6 +5673,13 @@ snapshots:
       statuses: 2.0.2
       toidentifier: 1.0.1
 
+  http-proxy-agent@7.0.2:
+    dependencies:
+      agent-base: 7.1.4
+      debug: 4.4.3
+    transitivePeerDependencies:
+      - supports-color
+
   http_ece@1.2.0: {}
 
   https-proxy-agent@7.0.6:
@@ -5382,6 +5689,10 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
+  iconv-lite@0.6.3:
+    dependencies:
+      safer-buffer: 2.1.2
+
   iconv-lite@0.7.2:
     dependencies:
       safer-buffer: 2.1.2
@@ -5415,6 +5726,8 @@ snapshots:
 
   is-interactive@1.0.0: {}
 
+  is-potential-custom-element-name@1.0.1: {}
+
   is-promise@4.0.0: {}
 
   is-unicode-supported@0.1.0: {}
@@ -5441,6 +5754,33 @@ snapshots:
     dependencies:
       argparse: 2.0.1
 
+  jsdom@26.1.0:
+    dependencies:
+      cssstyle: 4.6.0
+      data-urls: 5.0.0
+      decimal.js: 10.6.0
+      html-encoding-sniffer: 4.0.0
+      http-proxy-agent: 7.0.2
+      https-proxy-agent: 7.0.6
+      is-potential-custom-element-name: 1.0.1
+      nwsapi: 2.2.24
+      parse5: 7.3.0
+      rrweb-cssom: 0.8.0
+      saxes: 6.0.0
+      symbol-tree: 3.2.4
+      tough-cookie: 5.1.2
+      w3c-xmlserializer: 5.0.0
+      webidl-conversions: 7.0.0
+      whatwg-encoding: 3.1.1
+      whatwg-mimetype: 4.0.0
+      whatwg-url: 14.2.0
+      ws: 8.21.0
+      xml-name-validator: 5.0.0
+    transitivePeerDependencies:
+      - bufferutil
+      - supports-color
+      - utf-8-validate
+
   jsesc@3.1.0: {}
 
   json-parse-even-better-errors@2.3.1: {}
@@ -5533,6 +5873,8 @@ snapshots:
 
   loupe@3.2.1: {}
 
+  lru-cache@10.4.3: {}
+
   lru-cache@11.5.1: {}
 
   lru-cache@5.1.1:
@@ -5544,6 +5886,8 @@ snapshots:
       lodash.clonedeep: 4.5.0
       lru-cache: 11.5.1
 
+  lz-string@1.5.0: {}
+
   magic-string@0.30.17:
     dependencies:
       '@jridgewell/sourcemap-codec': 1.5.5
@@ -5640,6 +5984,8 @@ snapshots:
 
   notepack.io@3.0.1: {}
 
+  nwsapi@2.2.24: {}
+
   nypm@0.6.8:
     dependencies:
       citty: 0.2.2
@@ -5689,6 +6035,10 @@ snapshots:
       json-parse-even-better-errors: 2.3.1
       lines-and-columns: 1.2.4
 
+  parse5@7.3.0:
+    dependencies:
+      entities: 6.0.1
+
   parseurl@1.3.3: {}
 
   path-scurry@2.0.2:
@@ -5739,6 +6089,12 @@ snapshots:
       picocolors: 1.1.1
       source-map-js: 1.2.1
 
+  pretty-format@27.5.1:
+    dependencies:
+      ansi-regex: 5.0.1
+      ansi-styles: 5.2.0
+      react-is: 17.0.2
+
   prisma@6.19.3(typescript@5.9.3):
     dependencies:
       '@prisma/config': 6.19.3
@@ -5781,6 +6137,8 @@ snapshots:
       react: 19.2.7
       scheduler: 0.27.0
 
+  react-is@17.0.2: {}
+
   react-refresh@0.17.0: {}
 
   react@19.2.7: {}
@@ -5853,6 +6211,8 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
+  rrweb-cssom@0.8.0: {}
+
   rxjs@7.8.1:
     dependencies:
       tslib: 2.8.1
@@ -5865,6 +6225,10 @@ snapshots:
 
   safer-buffer@2.1.2: {}
 
+  saxes@6.0.0:
+    dependencies:
+      xmlchars: 2.2.0
+
   scheduler@0.27.0: {}
 
   schema-utils@3.3.0:
@@ -6053,6 +6417,8 @@ snapshots:
 
   symbol-observable@4.0.0: {}
 
+  symbol-tree@3.2.4: {}
+
   tapable@2.3.3: {}
 
   terser-webpack-plugin@5.6.1(webpack@5.106.2):
@@ -6095,6 +6461,12 @@ snapshots:
 
   tinyspy@4.0.4: {}
 
+  tldts-core@6.1.86: {}
+
+  tldts@6.1.86:
+    dependencies:
+      tldts-core: 6.1.86
+
   toidentifier@1.0.1: {}
 
   token-types@6.1.2:
@@ -6103,6 +6475,14 @@ snapshots:
       '@tokenizer/token': 0.3.0
       ieee754: 1.2.1
 
+  tough-cookie@5.1.2:
+    dependencies:
+      tldts: 6.1.86
+
+  tr46@5.1.1:
+    dependencies:
+      punycode: 2.3.1
+
   tree-kill@1.2.2: {}
 
   ts-interface-checker@0.1.13: {}
@@ -6249,7 +6629,7 @@ snapshots:
       jiti: 2.7.0
       terser: 5.48.0
 
-  vitest@3.2.6(@types/node@26.0.1)(jiti@2.7.0)(terser@5.48.0):
+  vitest@3.2.6(@types/node@26.0.1)(jiti@2.7.0)(jsdom@26.1.0)(terser@5.48.0):
     dependencies:
       '@types/chai': 5.2.3
       '@vitest/expect': 3.2.6
@@ -6276,6 +6656,7 @@ snapshots:
       why-is-node-running: 2.3.0
     optionalDependencies:
       '@types/node': 26.0.1
+      jsdom: 26.1.0
     transitivePeerDependencies:
       - jiti
       - less
@@ -6290,6 +6671,10 @@ snapshots:
       - tsx
       - yaml
 
+  w3c-xmlserializer@5.0.0:
+    dependencies:
+      xml-name-validator: 5.0.0
+
   watchpack@2.5.2:
     dependencies:
       graceful-fs: 4.2.11
@@ -6308,6 +6693,8 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
+  webidl-conversions@7.0.0: {}
+
   webpack-node-externals@3.0.0: {}
 
   webpack-sources@3.5.0: {}
@@ -6352,6 +6739,17 @@ snapshots:
       - postcss
       - uglify-js
 
+  whatwg-encoding@3.1.1:
+    dependencies:
+      iconv-lite: 0.6.3
+
+  whatwg-mimetype@4.0.0: {}
+
+  whatwg-url@14.2.0:
+    dependencies:
+      tr46: 5.1.1
+      webidl-conversions: 7.0.0
+
   why-is-node-running@2.3.0:
     dependencies:
       siginfo: 2.0.0
@@ -6369,6 +6767,10 @@ snapshots:
 
   ws@8.21.0: {}
 
+  xml-name-validator@5.0.0: {}
+
+  xmlchars@2.2.0: {}
+
   xmlhttprequest-ssl@2.1.2: {}
 
   yallist@3.1.1: {}
diff --git a/scripts/check-import-boundary.mjs b/scripts/check-import-boundary.mjs
index 8294bc1..bfde152 100644
--- a/scripts/check-import-boundary.mjs
+++ b/scripts/check-import-boundary.mjs
@@ -20,6 +20,10 @@ const ALLOWED = {
   '@insignia/iios-adapter-sdk': ['@insignia/iios-contracts'],
   '@insignia/iios-service': ['@insignia/iios-contracts', '@insignia/iios-testkit', '@insignia/iios-adapter-sdk'],
   '@insignia/iios-message-web': ['@insignia/iios-contracts', '@insignia/iios-kernel-client'],
+  // Core is transport-free; only ./adapters/kernel may import the kernel client.
+  // This map is package-level and cannot express that subpath rule — the finer
+  // constraint is enforced by packages/iios-messaging-ui/src/boundary.test.ts.
+  '@insignia/iios-messaging-ui': ['@insignia/iios-kernel-client'],
   '@insignia/iios-inbox-web': ['@insignia/iios-contracts', '@insignia/iios-kernel-client'],
   '@insignia/iios-community-web': ['@insignia/iios-contracts', '@insignia/iios-kernel-client'],
   '@insignia/iios-ai-web': ['@insignia/iios-contracts', '@insignia/iios-kernel-client'],