fix(calls): DM-aware rejoin toast, and no rejoining a DM call that ended (#302)

After a reload during a DM call the toast said "You were in the call in
Bob Builder"; it now says "You were in a call with Bob Builder". DM
calls are never auto-rejoined (it could ring the other person), and if
they have left by the time you tap, the toast says "Call ended" instead
of starting a new, ringing call.

Fixes #302

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

src/app/utils/callRejoin.test.ts

@@ -1,6 +1,12 @@
 import { describe, it } from 'node:test';
 import assert from 'node:assert/strict';
-import { CALL_REJOIN_MAX_AGE_MS, decideRejoin, RejoinContext } from './callRejoin';
+import {
+  CALL_REJOIN_MAX_AGE_MS,
+  decideRejoin,
+  othersInCall,
+  rejoinToastBody,
+  RejoinContext,
+} from './callRejoin';
 
 const base: RejoinContext = {
   record: {
@@ -54,3 +60,21 @@ describe('decideRejoin', () => {
     });
   });
 });
+
+it('decideRejoin: DM calls are never auto-rejoined, only offered (#302)', () => {
+  assert.deepEqual(decideRejoin({ ...base, mode: 'auto', dm: true }), {
+    action: 'ask',
+    roomId: '!r',
+  });
+  assert.deepEqual(decideRejoin({ ...base, mode: 'auto' }), { action: 'auto', roomId: '!r' });
+});
+
+it('rejoinToastBody and othersInCall (#302)', () => {
+  assert.equal(
+    rejoinToastBody('Bob Builder', true),
+    'You were in a call with Bob Builder before the restart. Tap to rejoin.',
+  );
+  assert.match(rejoinToastBody('Voice Lounge', false), /in the call in Voice Lounge/);
+  assert.equal(othersInCall(['@me:x'], '@me:x'), false);
+  assert.equal(othersInCall(['@me:x', '@bob:x'], '@me:x'), true);
+});

src/app/utils/callRejoin.ts

@@ -67,6 +67,8 @@ export type RejoinContext = {
   ownMemberDevices: string[];
   /** Number of call memberships in the room, ours included. */
   memberCount: number;
+  /** A DM call: rejoining one may ring the other person. */
+  dm?: boolean;
 };
 
 export type RejoinDecision = { action: 'none' } | { action: 'ask' | 'auto'; roomId: string };
@@ -83,5 +85,18 @@ export function decideRejoin(ctx: RejoinContext): RejoinDecision {
   // Nobody there any more (our own stale membership doesn't count).
   const others = ctx.memberCount - ctx.ownMemberDevices.length;
   if (others <= 0) return { action: 'none' };
+  // [Gitea #302] Never rejoin a DM call on our own: if the other person has
+  // just left, starting it again would ring them. Ask instead.
+  if (ctx.dm && mode === 'auto') return { action: 'ask', roomId: record.roomId };
   return { action: mode, roomId: record.roomId };
 }
+
+/** Pure: whether anyone but us is still in the call (by call membership). */
+export const othersInCall = (memberUserIds: string[], myUserId: string): boolean =>
+  memberUserIds.some((u) => u !== myUserId);
+
+/** The rejoin toast's text; DMs name the person rather than "the call in <room>". */
+export const rejoinToastBody = (roomName: string | undefined, dm: boolean): string =>
+  dm
+    ? `You were in a call with ${roomName ?? 'them'} before the restart. Tap to rejoin.`
+    : `You were in the call in ${roomName ?? 'a room'} before the restart. Tap to rejoin.`;