feat(desktop): Tier A desktop features — web side (P5-46/36/44/43/49/47/55/57)

Web half of the desktop feature wave. A shared bridge (`hooks/useTauri.ts`:
invokeTauri/isTauri/useTauriEvent) backs per-feature hooks that no-op in the
browser and drive the native Tauri commands (compiled in cinny-desktop):

- P5-46 useTauriCallPower — hold system awake while a call is active.
- P5-36 useTauriJumpList — Windows jump list of recent rooms → matrix: deep links.
- P5-44 useTauriThumbbar — taskbar Mute/Deafen/End; events toggle mic/sound/hangup.
- P5-43 useTauriSmtc — SMTC call state + button events.
- P5-49 useTauriNetwork — react to native network-change → mx.retryImmediately().
- P5-47 window chrome — opt-in `customWindowChromeAtom` + TDS `TitleBar`; DesktopChrome
  wrapper in App.tsx (zero layout impact when off) + a desktop-only settings toggle.
- P5-55 composer toolbar drag-reorder (settings order[] + pragmatic-drag-and-drop).
- P5-57 DraftIndicator — subtle "draft saved" cue in the composer.

Client-scoped hooks mount via TauriDesktopFeatures in ClientNonUIFeatures; window
chrome mounts at App level. Gates: tsc/eslint/prettier clean, build OK, 556 tests.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/hooks/useTauri.ts

@@ -0,0 +1,35 @@
+import { useEffect, useRef } from 'react';
+
+// Tauri v2 injects `__TAURI_INTERNALS__` into the webview at runtime; we use it
+// directly so cinny doesn't need `@tauri-apps/api` as a dependency. Native Rust
+// modules push data back to the web by dispatching DOM CustomEvents (see
+// `emit_to_web` in cinny-desktop's `native` module), which `useTauriEvent`
+// subscribes to. This module is the single source for the desktop bridge that
+// every `useTauri*` feature hook builds on.
+type Invoke = (cmd: string, args?: Record<string, unknown>) => Promise<unknown>;
+
+export const tauriInvoke = (): Invoke | undefined =>
+  (window as unknown as { __TAURI_INTERNALS__?: { invoke: Invoke } }).__TAURI_INTERNALS__?.invoke;
+
+export const isTauri = (): boolean => tauriInvoke() !== undefined;
+
+/** Fire-and-forget invoke that no-ops (and never throws) outside Tauri. */
+export const invokeTauri = (cmd: string, args?: Record<string, unknown>): void => {
+  tauriInvoke()?.(cmd, args).catch(() => undefined);
+};
+
+/**
+ * Subscribe to a CustomEvent dispatched from the Rust side via `emit_to_web`.
+ * The handler is kept in a ref so callers don't need to memoize it to avoid
+ * re-subscribing. No-op outside Tauri.
+ */
+export function useTauriEvent<T = unknown>(name: string, handler: (detail: T) => void): void {
+  const handlerRef = useRef(handler);
+  handlerRef.current = handler;
+  useEffect(() => {
+    if (!isTauri()) return undefined;
+    const listener = (e: Event): void => handlerRef.current((e as CustomEvent<T>).detail);
+    window.addEventListener(name, listener);
+    return () => window.removeEventListener(name, listener);
+  }, [name]);
+}

src/app/hooks/useTauriCallPower.ts

@@ -0,0 +1,18 @@
+import { useEffect } from 'react';
+import { useAtomValue } from 'jotai';
+import { callEmbedAtom } from '../state/callEmbed';
+import { invokeTauri } from './useTauri';
+
+/**
+ * P5-46 — keep the system awake during calls (call continuity). Mirrors the
+ * call-embed atom (undefined = no active call) onto the native `set_call_active`
+ * command, which holds a `SetThreadExecutionState` request on Windows while a
+ * voice/video call is active and releases it when the call ends. No-op in the
+ * browser.
+ */
+export function useTauriCallPower(): void {
+  const callEmbed = useAtomValue(callEmbedAtom);
+  useEffect(() => {
+    invokeTauri('set_call_active', { active: callEmbed !== undefined });
+  }, [callEmbed]);
+}

src/app/hooks/useTauriJumpList.ts

@@ -0,0 +1,58 @@
+import { useEffect } from 'react';
+import { useAtomValue } from 'jotai';
+import { Room } from 'matrix-js-sdk';
+import { allRoomsAtom } from '../state/room-list/roomList';
+import { useMatrixClient } from './useMatrixClient';
+import { isTauri, invokeTauri } from './useTauri';
+
+/** Cap the Jump List to a small, glanceable set of rooms. */
+const MAX_ITEMS = 8;
+
+/** Wait for room activity to settle before re-publishing the (native) list. */
+const DEBOUNCE_MS = 1500;
+
+type JumpItem = { title: string; uri: string };
+
+/**
+ * Build the `matrix:` deep link the desktop deep-link handler understands (see
+ * `useDeepLinkNavigate`): `matrix:r/<alias>` for a canonical alias, otherwise
+ * `matrix:roomid/<id>`. The sigil is dropped and the remainder is percent-encoded
+ * because the handler decodes each segment with `decodeURIComponent`.
+ */
+const roomToUri = (room: Room): string => {
+  const alias = room.getCanonicalAlias();
+  if (alias && alias.startsWith('#')) {
+    return `matrix:r/${encodeURIComponent(alias.slice(1))}`;
+  }
+  return `matrix:roomid/${encodeURIComponent(room.roomId.slice(1))}`;
+};
+
+/**
+ * P5-36 — publish a Windows taskbar Jump List of the most recently-active rooms.
+ * Rooms come from `allRoomsAtom` (the joined-room list), sorted by
+ * `getLastActiveTimestamp` (mirroring the sort used elsewhere, e.g. the forward
+ * dialog), with spaces excluded. The list is pushed to the native
+ * `set_jump_list` command, debounced so bursts of activity don't thrash the
+ * shell. No-op outside Tauri.
+ */
+export function useTauriJumpList(): void {
+  const mx = useMatrixClient();
+  const allRooms = useAtomValue(allRoomsAtom);
+
+  useEffect(() => {
+    if (!isTauri()) return undefined;
+
+    const timeout = setTimeout(() => {
+      const items: JumpItem[] = allRooms
+        .map((roomId) => mx.getRoom(roomId))
+        .filter((room): room is Room => room !== null && !room.isSpaceRoom())
+        .sort((a, b) => (b.getLastActiveTimestamp() ?? 0) - (a.getLastActiveTimestamp() ?? 0))
+        .slice(0, MAX_ITEMS)
+        .map((room) => ({ title: room.name || room.roomId, uri: roomToUri(room) }));
+
+      invokeTauri('set_jump_list', { items });
+    }, DEBOUNCE_MS);
+
+    return () => clearTimeout(timeout);
+  }, [mx, allRooms]);
+}

src/app/hooks/useTauriNetwork.ts

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+import { useRef, useState } from 'react';
+import { useMatrixClient } from './useMatrixClient';
+import { useTauriEvent } from './useTauri';
+
+/** Detail shape of the `network-changed` event emitted by the native side. */
+type NetworkChangedDetail = {
+  online: boolean;
+};
+
+/**
+ * P5-49 — Network awareness (desktop). Subscribes to the native
+ * `network-changed` event (Windows Network List Manager poll, `{ online }`) and,
+ * on a transition back to online, calls `mx.retryImmediately()` so the sync loop
+ * retries its backed-off `/sync` at once instead of waiting out the backoff
+ * timer. Returns the last known connectivity (`undefined` until the first
+ * event). Inert in the browser, since `useTauriEvent` only listens under Tauri.
+ */
+export function useTauriNetwork(): boolean | undefined {
+  const mx = useMatrixClient();
+  const [online, setOnline] = useState<boolean | undefined>(undefined);
+  // Track the previous value in a ref so we can detect an offline -> online
+  // transition without adding it to a dependency list.
+  const onlineRef = useRef<boolean | undefined>(undefined);
+
+  useTauriEvent<NetworkChangedDetail>('network-changed', ({ online: next }) => {
+    const previous = onlineRef.current;
+    onlineRef.current = next;
+    setOnline(next);
+    // Only nudge the client when connectivity is (re)gained. The initial event
+    // (previous === undefined) also triggers a retry, which is safe: it's a
+    // no-op if nothing is backed off.
+    if (next && previous !== true) {
+      mx.retryImmediately();
+    }
+  });
+
+  return online;
+}

src/app/hooks/useTauriSmtc.ts

@@ -0,0 +1,38 @@
+import { useEffect } from 'react';
+import { useAtomValue } from 'jotai';
+import { callEmbedAtom } from '../state/callEmbed';
+import { useCallControlState } from '../plugins/call';
+import { invokeTauri, useTauriEvent } from './useTauri';
+
+/**
+ * P5-43 — expose the active call to the Windows System Media Transport Controls
+ * (the volume-flyout / media overlay). Mirrors the call-embed atom (undefined =
+ * no active call) and the current mic state onto the native
+ * `set_smtc_call_state` command, and translates SMTC button presses back into
+ * call actions:
+ *   - Play/Pause (`smtc-action` → `mute`) toggles the microphone.
+ *   - Stop (`smtc-action` → `end`) hangs up the call.
+ * No-op in the browser (the native command and events only fire under Tauri).
+ */
+type SmtcAction = { action: 'mute' | 'end' };
+
+export function useTauriSmtc(): void {
+  const callEmbed = useAtomValue(callEmbedAtom);
+  // `microphone` reflects mic-enabled; muted is its inverse while in a call.
+  const { microphone } = useCallControlState(callEmbed?.control);
+  const active = callEmbed !== undefined;
+  const muted = active && !microphone;
+
+  useEffect(() => {
+    invokeTauri('set_smtc_call_state', { active, muted });
+  }, [active, muted]);
+
+  useTauriEvent<SmtcAction>('smtc-action', ({ action }) => {
+    if (!callEmbed) return;
+    if (action === 'mute') {
+      callEmbed.control.toggleMicrophone().catch(() => undefined);
+    } else if (action === 'end') {
+      callEmbed.hangup().catch(() => undefined);
+    }
+  });
+}

src/app/hooks/useTauriThumbbar.ts

@@ -0,0 +1,43 @@
+import { useEffect } from 'react';
+import { useAtomValue } from 'jotai';
+import { callEmbedAtom } from '../state/callEmbed';
+import { useCallControlState } from '../plugins/call';
+import { invokeTauri, useTauriEvent } from './useTauri';
+
+type ThumbbarAction = { action: 'mute' | 'deafen' | 'end' };
+
+/**
+ * P5-44 — Taskbar thumbnail toolbar (call controls). While a call is active,
+ * mirrors the mic/sound state onto the native `set_thumbbar` command (three
+ * Mute / Deafen / End-Call buttons on the Windows taskbar thumbnail toolbar) and
+ * hides them when the call ends. Thumb-button clicks come back as the
+ * `thumbbar-action` event and drive the real call controls. No-op in the browser.
+ */
+export function useTauriThumbbar(): void {
+  const callEmbed = useAtomValue(callEmbedAtom);
+  const { microphone, sound } = useCallControlState(callEmbed?.control);
+
+  const active = callEmbed !== undefined;
+  // Muted / deafened only make sense while a call is active; report false
+  // otherwise so the buttons render in a sane (hidden) state.
+  const muted = active && !microphone;
+  const deafened = active && !sound;
+
+  useEffect(() => {
+    invokeTauri('set_thumbbar', { active, muted, deafened });
+  }, [active, muted, deafened]);
+
+  useTauriEvent<ThumbbarAction>('thumbbar-action', ({ action }) => {
+    if (!callEmbed) return;
+    if (action === 'mute') {
+      // toggleMicrophone flips the mic; `microphone === false` means muted.
+      callEmbed.control.toggleMicrophone();
+    } else if (action === 'deafen') {
+      // toggleSound flips local audio; `sound === false` means deafened. It also
+      // mutes the mic while deafened, matching the in-app Deafen control.
+      callEmbed.control.toggleSound();
+    } else if (action === 'end') {
+      callEmbed.hangup();
+    }
+  });
+}

src/app/hooks/useTauriWindowChrome.ts

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+import { useEffect } from 'react';
+import { useAtomValue } from 'jotai';
+import { customWindowChromeAtom } from '../state/customWindowChrome';
+import { invokeTauri, isTauri } from './useTauri';
+
+/**
+ * P5-47 — drive the native window frame from the `customWindowChromeAtom`.
+ *
+ * On mount and whenever the atom changes, pushes the value onto the native
+ * `set_custom_chrome` command: `enabled = true` strips the OS decorations so the
+ * web `<TitleBar/>` can take over, `enabled = false` restores the native frame.
+ * No-op in the browser (`isTauri()` guard), so it's safe to call unconditionally
+ * from the app shell.
+ */
+export function useTauriWindowChrome(): void {
+  const enabled = useAtomValue(customWindowChromeAtom);
+
+  useEffect(() => {
+    if (!isTauri()) return;
+    invokeTauri('set_custom_chrome', { enabled });
+  }, [enabled]);
+}