## Problem
Chat titles revert to the fallback truncated title after briefly showing
the AI-generated title. Even reloading the page doesn't help — the
correct title flashes then gets overwritten.
## Root Cause
Single bug, two symptoms.
In `processChat` (`coderd/chatd/chatd.go`), the `chat` variable is
passed by value. The flow:
1. `processChat(ctx, chat)` receives `chat` with the initial fallback
title (truncated first message).
2. Inside `runChat`, `maybeGenerateChatTitle` generates an AI title,
writes it to the DB via `UpdateChatByID`, and publishes a `title_change`
event. **The DB has the correct title.** The client briefly displays it.
3. `runChat` returns. The **deferred cleanup** in `processChat`
publishes `publishChatPubsubEvent(chat, StatusChange)` — but `chat` here
is the original value copy that still has the **old fallback title**.
4. The frontend receives the `status_change` SSE event and
**unconditionally applies `title` from every event kind** (see
`AgentsPage.tsx` line ~305: `title: updatedChat.title`). This overwrites
the correct AI title with the stale fallback.
**Why reload doesn't help:** If the chat is still processing when the
page reloads, `listChats` loads the correct title from the DB, but then
the deferred `status_change` event arrives moments later and clobbers
it. The title was always in the DB — it was the pubsub event that kept
overwriting it.
## Fix
Re-read the chat from the database in the deferred cleanup before
publishing the final `status_change` event, so it carries the current
(AI-generated) title.
Kyle Carberry
ff687aa780