fix(presence): Do Not Disturb is real "busy" presence and keeps your status (#283)

DND was sent as presence unavailable with the literal status text
"dnd": it replaced your status, and other clients showed "dnd". Where
the server supports MSC3026 (busy_presence), DND now sends presence
org.matrix.msc3026.busy and leaves the status alone (Synapse keeps
busy across /sync set_presence=online). Busy renders as red "Do Not
Disturb" with the real status line; the legacy unavailable + "dnd"
encoding is still recognised and still used on servers without it.
Status saves / clears no longer downgrade busy. The SDK rejects
non-spec presences, so busy goes through a direct authed PUT.

Fixes #283

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/hooks/usePresenceUpdater.ts

@@ -1,20 +1,27 @@
 import { useEffect, useRef } from 'react';
 import { SetPresence } from 'matrix-js-sdk';
-import { PresenceDeduper, PresenceWrite } from '../utils/presenceWrite';
+import { PresenceDeduper, PresenceWrite, writePresence } from '../utils/presenceWrite';
 import { useMatrixClient } from './useMatrixClient';
 import { getLastLocalStatusWrite, pickHeartbeatStatus } from '../utils/ownStatusSync';
 import { useSetting } from '../state/hooks/settings';
 import { settingsAtom } from '../state/settings';
+import {
+  BUSY_PRESENCE,
+  BUSY_PRESENCE_FEATURE,
+  isBusyPresenceSupported,
+  setBusyPresenceSupported,
+} from '../utils/busyPresence';
 
 const IDLE_TIMEOUT_MS = 10 * 60 * 1000;
 const ACTIVITY_THROTTLE_MS = 1000;
 
 export type PresenceSetting = 'auto' | 'online' | 'idle' | 'dnd' | 'invisible';
-export type PresenceState = 'online' | 'unavailable' | 'offline';
+export type PresenceState = 'online' | 'unavailable' | 'offline' | typeof BUSY_PRESENCE;
 
 /**
  * Single source of truth for mapping the user's presence preference to the
- * Matrix presence value: auto/online → 'online', idle/dnd → 'unavailable',
+ * Matrix presence value: auto/online → 'online', idle → 'unavailable', dnd →
+ * MSC3026 busy (or 'unavailable' where the server lacks it),
  * invisible (or the hidePresence override) → 'offline'. Shared with the Profile
  * status writer so setting/clearing a status message never overrides the user's
  * chosen presence (e.g. outing an Invisible user as online).
@@ -24,7 +31,10 @@ export function presenceStateFromSetting(
   hidePresence: boolean,
 ): PresenceState {
   if (hidePresence || presenceStatus === 'invisible') return 'offline';
-  if (presenceStatus === 'idle' || presenceStatus === 'dnd') return 'unavailable';
+  // [Gitea #283] DND is MSC3026 busy where the server supports it, so status
+  // writes (save / clear / auto-clear) don't downgrade it to "unavailable".
+  if (presenceStatus === 'dnd') return isBusyPresenceSupported() ? BUSY_PRESENCE : 'unavailable';
+  if (presenceStatus === 'idle') return 'unavailable';
   return 'online';
 }
 
@@ -62,8 +72,7 @@ export function usePresenceUpdater() {
     // by a heartbeat that changed nothing.
     const send = (write: PresenceWrite, label: string) => {
       if (!deduper.shouldSend(write)) return Promise.resolve();
-      return mx
-        .setPresence(write)
+      return writePresence(mx, write)
         .then(() => deduper.sent(write))
         .catch((err) => warnPresenceFailure(label, err));
     };
@@ -134,7 +143,22 @@ export function usePresenceUpdater() {
       return undefined;
     }
     if (presenceStatus === 'dnd') {
-      setUnavailable('dnd');
+      // [Gitea #283] Real "busy" presence where supported: the status text
+      // stays yours. /sync reporting "online" doesn't override busy on
+      // Synapse, so the sync loop can stay online. Older servers keep the
+      // legacy unavailable + "dnd" text encoding.
+      mx.doesServerSupportUnstableFeature(BUSY_PRESENCE_FEATURE)
+        .catch(() => false)
+        .then(async (busy) => {
+          setBusyPresenceSupported(busy);
+          if (!busy) {
+            setUnavailable('dnd');
+            return;
+          }
+          syncPresence(SetPresence.Online);
+          const status = await resolveStatus();
+          send({ presence: BUSY_PRESENCE, ...(status ? { status_msg: status } : {}) }, 'busy');
+        });
       return undefined;
     }