Sync: a flag set on the server left the thread counters stale

Reported from the running app: a message showed as unread in the list — bold, blue dot — while the reading pane showed it as read, and only a manual "mark as read" reconciled them. The two views read different things. The pane reads the message's own flags; the list reads `threads.unread_count`, denormalized from them. `apply_delta` updated message flags with a bare UPDATE and never recomputed the thread, so a flag set anywhere but in this app — read on a phone, filed by a server-side rule — moved one and not the other. Auto-mark-on-read could not fix it either: it sees a message that is already \Seen and correctly does nothing, leaving the counter wrong forever. Expunges had the same hole, which also left `message_count` overstated. `apply_delta` now collects the affected threads and re-denormalizes them after the deletes, so a thread emptied by an expunge is removed rather than recounted. Migration 0018 repairs rows that already drifted — recomputed from the messages, so it is a no-op on a healthy database. One thread was stale here; installs that have been syncing longer will have more. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_018SqJYt7jD7oUEkoY68sBZo
2026-09-18 18:21:30 +02:00
parent de79b4ba07
commit e58a2f0ef4
3 changed files with 163 additions and 6 deletions
@@ -241,3 +241,79 @@ async def test_apply_delta_expunges_vanished_uids() -> None:  # type: ignore[no-
            await cleanup.execute(delete(User).where(User.id == user.id))
        await session.close()
        await engine.dispose()
+
+
+async def test_server_side_flag_change_updates_the_thread_counters() -> None:
+    """A flag set elsewhere (phone, webmail, server rule) must re-denormalize.
+
+    `threads.unread_count` is what the message list renders, while the reading
+    pane renders the message's own flags. When a delta updated flags without
+    recomputing the thread, the two disagreed forever: the list kept showing a
+    message as unread that the pane showed as read, and only a manual "mark as
+    read" — which goes through a different path — reconciled them.
+    """
+    from app.models import Thread
+    from app.threading_.threader import denormalize_thread
+
+    engine = create_async_engine(get_settings().database_url, poolclass=NullPool)
+    sm = async_sessionmaker(engine, expire_on_commit=False)
+    session = sm()
+    user = User(handle=f"fc{uuid.uuid4().hex[:8]}@test.local", password_hash=hash_password("pw"))
+    session.add(user)
+    await session.flush()
+    account = Account(
+        user_id=user.id,
+        email="me@example.com",
+        imap_config={},
+        smtp_config={},
+        secret_ct=b"",
+        discovery_src="manual",
+    )
+    session.add(account)
+    await session.flush()
+    inbox = Mailbox(
+        account_id=account.id, user_id=user.id, path="INBOX", special_use="inbox", last_seen_uid=5
+    )
+    thread = Thread(user_id=user.id, subject_norm="t", last_message_at=datetime.now(UTC))
+    session.add_all([inbox, thread])
+    await session.flush()
+    message = Message(
+        user_id=user.id,
+        account_id=account.id,
+        mailbox_id=inbox.id,
+        thread_id=thread.id,
+        uid=5,
+        internal_date=datetime.now(UTC),
+        blob_sha256="0" * 64,
+        flags=[],
+    )
+    session.add(message)
+    await session.flush()
+    await denormalize_thread(session, thread.id)
+    await session.commit()
+    assert (await session.get(Thread, thread.id)).unread_count == 1
+
+    class FakeProvider:
+        qresync_enabled = True
+
+        async def close(self) -> None:
+            return None
+
+    class _FlagChange:
+        uid = 5
+        flags = ["\\Seen"]
+
+    delta = MailboxDelta([], [_FlagChange()], [], None, None)
+    await sync_engine.apply_delta(FakeProvider(), account, inbox, delta)  # type: ignore[arg-type]
+
+    try:
+        session.expunge_all()
+        refreshed = await session.get(Thread, thread.id)
+        assert refreshed.unread_count == 0, (
+            "the server said the message was read; the thread counter did not follow"
+        )
+    finally:
+        async with session_scope() as cleanup:
+            await cleanup.execute(delete(User).where(User.id == user.id))
+        await session.close()
+        await engine.dispose()