feat(service): P2.1 messaging tables — IiosMessageReceipt + IiosUnreadCounter

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/iios-service/prisma/schema.prisma

@@ -66,6 +66,15 @@ enum IiosDeliveryState {
   REDACTED
 }
 
+enum IiosReceiptKind {
+  DELIVERED
+  READ
+  ACKED
+  FAILED
+  SUPPRESSED
+  RATE_LIMITED
+}
+
 // ─── Kernel tables ────────────────────────────────────────────────
 
 /// Frozen six-vector scope. orgId + appId are REQUIRED (no global-by-null).
@@ -124,6 +133,8 @@ model IiosActorRef {
   threadsCreated     IiosThread[]            @relation("ThreadCreatedBy")
   participations     IiosThreadParticipant[]
   interactions       IiosInteraction[]
+  receipts           IiosMessageReceipt[]
+  unreadCounters     IiosUnreadCounter[]
 }
 
 /// A configured channel surface (PORTAL in P1).
@@ -163,8 +174,9 @@ model IiosThread {
   updatedAt        DateTime  @updatedAt
   metadata         Json?
 
-  participants IiosThreadParticipant[]
-  interactions IiosInteraction[]
+  participants   IiosThreadParticipant[]
+  interactions   IiosInteraction[]
+  unreadCounters IiosUnreadCounter[]
 
   @@index([scopeId, status])
 }
@@ -207,7 +219,8 @@ model IiosInteraction {
   traceId             String?
   metadata            Json?
 
-  parts IiosMessagePart[]
+  parts    IiosMessagePart[]
+  receipts IiosMessageReceipt[]
 
   @@unique([scopeId, idempotencyKey])
   @@index([threadId, occurredAt])
@@ -255,3 +268,34 @@ model IiosProcessedEvent {
 
   @@id([consumerName, eventId])
 }
+
+// ─── P2: messaging — receipts & unread ────────────────────────────
+
+/// Delivery/read receipt for a message interaction, per actor.
+model IiosMessageReceipt {
+  id                String          @id @default(cuid())
+  interactionId     String
+  interaction       IiosInteraction @relation(fields: [interactionId], references: [id], onDelete: Cascade)
+  actorId           String?
+  actor             IiosActorRef?   @relation(fields: [actorId], references: [id])
+  receiptKind       IiosReceiptKind
+  occurredAt        DateTime        @default(now())
+  providerReceiptRef String?
+  metadata          Json?
+
+  @@unique([interactionId, actorId, receiptKind])
+  @@index([interactionId])
+}
+
+/// Per-(thread, actor) unread count + last-read marker.
+model IiosUnreadCounter {
+  threadId             String
+  thread               IiosThread       @relation(fields: [threadId], references: [id], onDelete: Cascade)
+  actorId              String
+  actor                IiosActorRef     @relation(fields: [actorId], references: [id])
+  unreadCount          Int              @default(0)
+  lastReadInteractionId String?
+  updatedAt            DateTime         @updatedAt
+
+  @@id([threadId, actorId])
+}