fix(messaging-ui): portal compose modal to <body> so it renders above host chrome

A host wrapper like .view{position:relative;z-index:1} creates a stacking context that traps the modal's fixed overlay below a sibling sticky header, no matter its z-index. Render the modal through a ModalPortal (createPortal to document.body) so it escapes the host stacking context + overflow entirely; the portal root copies the SDK theme tokens from the live surface (synchronously, no unstyled paint) and carries dark defaults as a fallback. Adds react-dom peer dep. 67 tests green. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-07-22 18:19:25 +05:30
parent f16d7986c7
commit 9882177c59
6 changed files with 60 additions and 5 deletions
@@ -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);
+}