VS Code extension: Rename Session Tab persists the title but the editor tab label never refreshes (v2.1.270)

### What's Wrong?

`Claude Code: Rename Session Tab` **persists the new title correctly**, but the editor tab label keeps showing the old one. It stays stale indefinitely — until something unrelated causes the session state to be re-read.

There is no error and no notification. The rename genuinely succeeds: the new title is written to the session transcript as `customTitle`, and `renameSession` returns `skipped: false`. Only the label is wrong, so it reads as "rename doesn't work".

Things that *do* make the label catch up, all of which re-read session state:

- clicking the session in the session list (cheapest — one click)
- opening the session list at all
- closing and reopening the tab
- restarting the window

Note the ordering trap: restarting *before* renaming doesn't help, because the panel reads the title at creation. You have to rename first, then cause a refresh. That made it look intermittent for a while.

### What Should Happen?

The editor tab label should update as soon as the rename succeeds, the way it does when the session is renamed from the in-webview session list.

### Steps to Reproduce

1. Open a Claude Code session as an editor tab (`Claude Code: Open in New Tab`).
2. Command Palette → **Claude Code: Rename Session Tab**.
3. Type a new name and press Enter.
4. **Observe:** the editor tab label is unchanged. No error, no notification.
5. Confirm it actually persisted — the new title is in the session's transcript under `~/.claude/projects//.jsonl` as `"customTitle":""`.
6. Now click that session in the Claude session list. The tab label updates immediately to the name set in step 3.

### Analysis

From the shipped bundle in `anthropic.claude-code-2.1.270-win32-x64`:

The editor tab title is only ever assigned in response to a `rename_tab` message from the webview:

```js
else if ($.request.type === "rename_tab")
if (this.panelTab && typeof $.request.title === "string")
this.panelTab.title = GX($.request.title)
```

and that message is produced by a reactive effect reading the active session's summary:

```js
let q = this.activeSession.value?.summary.value,
V = (q && q.length > 25 ? q.substring(0, 24) + "…" : q) || "Claude Code";
wZ(() => J.renameTab(V, H, W));
```

The two rename routes then differ:

- **In-webview rename** (session list) sets `Z.summary.value = J` optimistically before awaiting the round trip. The effect re-evaluates, `rename_tab` is sent, the tab updates.
- **`claude-vscode.renameSessionTab`** writes to the store, then `handleSessionRenamed` calls `sendSessionRenamed`, which delivers `session_renamed` to the webview. The only handler there is:

```js
case "session_renamed":
this.sessionRenamedEvents.emit({ sessionId: $.request.sessionId, title: $.request.title });
break;
```

Nothing assigns `activeSession.summary`, so the effect never re-evaluates, `rename_tab` is never sent, and `panelTab.title` is never reassigned.

That accounts for every symptom: correct persistence, no error, stale label, and any subsequent re-read of session state fixing it.

**Suggested fix:** have the `session_renamed` handler update the matching session's `summary` (as the in-webview path already does), so the existing effect fires and the tab repaints. The rest of the machinery is already in place and working.

### Environment

- Extension: `anthropic.claude-code-2.1.270-win32-x64`
- VS Code on Windows 11
- Reproduced across several separate workspace folders

### Additional note

The extension registers one lock file per workspace folder under `~/.claude/ide/`. On this machine several VS Code windows shared a single `Code` process id across those lock files, so the symptom appeared in multiple windows at once and looked like one window blocking another. That turned out to be a red herring — it is the same missing refresh in each window, not cross-window interference. Renames were always applied to the correct session; I verified this by renaming to a unique string in one window and confirming it landed only on that window's transcript.

Locate the VS Code extension's session_renamed handler and the activeSession summary used by the rename_tab effect; compare them with the in-webview rename path described in the issue. Ensure a successful command-palette rename updates the matching session summary so the existing tab-title refresh runs, then verify the reproduction steps without requiring an unrelated session refresh.

Written by the indexing model from the issue text.