fix(dictation): extract tested computeDictationAvailability + gate mic from the reactive atom (#314 F1/F2)

F1: the availability publish-effect duplicated the #218 editability gate
(editable && inEditMode && !showStatic) inline — a copy that could silently
diverge from the tested isBodyEditable — and the reason computation (the core of
#309) had no tests. Extract computeDictationAvailability into editor-sync-state.ts
REUSING isBodyEditable; the effect is now a one-line call. Unit tests cover the
branches (synced→null; pre-sync disconnected→offline / else connecting;
!editable/!edit→read-only).

F2: DictationGroup gated the mic on the non-reactive editor.isEditable while the
PR already publishes the reactive dictationAvailability.isEditable (same signals)
— so gate and reason came from different sources and the mic could stick. Gate on
dictationAvailability.isEditable: one reactive source of truth for both.

vitest (editor-sync-state + dictation): 37 passed.

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

apps/client/src/features/editor/components/fixed-toolbar/groups/dictation-group.test.tsx

@@ -1,36 +1,15 @@
 import { describe, it, expect, vi } from "vitest";
-import { useEffect, useState } from "react";
 import { render, act } from "@testing-library/react";
+import { Provider, createStore } from "jotai";
+import { dictationAvailabilityAtom } from "@/features/editor/atoms/editor-atoms.ts";
 
-// Regression test for #311: on a page the user can edit, the byline mic stayed
-// stuck disabled until an unrelated re-render happened, because DictationGroup
-// read the non-reactive field `editor.isEditable` directly. The fix reads it via
-// `useEditorState`, which subscribes to the editor's own events.
-//
-// The mock below mirrors the real `useEditorState` contract: it runs the
-// selector, and re-runs it (re-rendering the consumer) whenever the editor emits
-// an event. This is what makes the test faithful — with the pre-fix code
-// (`disabled={!editor.isEditable}`) DictationGroup never subscribes, so emitting
-// an event would NOT re-render and the mic would stay disabled.
-vi.mock("@tiptap/react", () => ({
-  useEditorState: ({ editor, selector }: any) => {
-    const [value, setValue] = useState(() => selector({ editor }));
-    useEffect(() => {
-      const handler = () => setValue(selector({ editor }));
-      editor.on("update", handler);
-      return () => editor.off("update", handler);
-    }, [editor, selector]);
-    return value;
-  },
-}));
-
-// The mic only cares about the workspace's streaming flag; return a stable stub.
-vi.mock("jotai", () => ({
-  useAtomValue: () => ({ settings: { ai: { dictationStreaming: false } } }),
-}));
-vi.mock("@/features/user/atoms/current-user-atom.ts", () => ({
-  workspaceAtom: {},
-}));
+// Regression test for the byline mic staying stuck disabled (#311 / #309): on a
+// page the user can edit, the mic must un-grey once the body becomes editable.
+// #311 first fixed this by reading `editor.isEditable` via `useEditorState`; #309
+// superseded that with a reactive `dictationAvailabilityAtom` that page-editor
+// publishes (carrying both the editable gate AND the unavailable reason). The mic
+// now gates on `dictationAvailability.isEditable`, so a change to that atom must
+// re-render the group and flip the disabled state (jotai drives the subscription).
 
 // Detectable stand-in that surfaces the `disabled` prop the component computes.
 vi.mock("@/features/dictation/components/mic-button", () => ({
@@ -41,33 +20,39 @@ vi.mock("@/features/dictation/components/mic-button", () => ({
 
 import { DictationGroup } from "./dictation-group";
 
-// Minimal editor stand-in: a mutable `isEditable` field plus a tiny event
-// emitter, matching the surface DictationGroup + the mocked useEditorState use.
-function makeFakeEditor(isEditable: boolean) {
-  const listeners = new Set<() => void>();
+// Minimal editor stand-in matching the surface DictationGroup uses (handleStart /
+// handleText). The disabled gate no longer reads this — it reads the atom.
+function makeFakeEditor() {
   return {
-    isEditable,
+    isEditable: false,
     isDestroyed: false,
     state: { selection: { from: 0, to: 0 }, doc: { content: { size: 0 } } },
-    on: (_event: string, cb: () => void) => listeners.add(cb),
-    off: (_event: string, cb: () => void) => listeners.delete(cb),
-    emit: () => listeners.forEach((cb) => cb()),
   } as any;
 }
 
-describe("DictationGroup editable reactivity (#311)", () => {
-  it("re-enables the mic when the editor flips isEditable false -> true", () => {
-    const editor = makeFakeEditor(false);
-    const { getByTestId } = render(<DictationGroup editor={editor} />);
+describe("DictationGroup editable reactivity (#309 atom / #311)", () => {
+  it("re-enables the mic when dictationAvailability flips isEditable false -> true", () => {
+    const editor = makeFakeEditor();
+    const store = createStore();
+    // Pre-sync: page editor publishes not-editable (with a reason).
+    store.set(dictationAvailabilityAtom, {
+      isEditable: false,
+      reason: "connecting",
+    });
 
-    // Pre-sync: not editable yet, so the mic is disabled (preserves #218 intent).
+    const { getByTestId } = render(
+      <Provider store={store}>
+        <DictationGroup editor={editor} />
+      </Provider>,
+    );
+
+    // Not editable yet -> disabled (preserves the #218 pre-sync intent).
     expect(getByTestId("mic").hasAttribute("disabled")).toBe(true);
 
-    // Collab sync flips the editor editable via editor.setEditable(true), which
-    // mutates the field and emits — the mic must react and enable itself.
+    // Collab sync -> page editor republishes editable; the atom change must
+    // re-render the group and enable the mic.
     act(() => {
-      editor.isEditable = true;
-      editor.emit();
+      store.set(dictationAvailabilityAtom, { isEditable: true, reason: null });
     });
 
     expect(getByTestId("mic").hasAttribute("disabled")).toBe(false);

apps/client/src/features/editor/components/fixed-toolbar/groups/dictation-group.tsx

@@ -83,7 +83,7 @@ export const DictationGroup: FC<Props> = ({ editor, color, iconSize }) => {
       streaming={streamingDictation}
       onStart={handleStart}
       onText={handleText}
-      disabled={!editor.isEditable}
+      disabled={!dictationAvailability.isEditable}
       unavailableReason={dictationAvailability.reason ?? undefined}
       color={color}
       iconSize={iconSize}