macOS: Session sidebar is a one-time snapshot at startup; sessions from other Desktop instances never appear

Steps to reproduce

1. Launch two Claude Code Desktop instances simultaneously (e.g. via claude from the command line to bypass macOS single-instance enforcement).
2. In instance A, create one or more new chat sessions.
3. Switch to instance B and observe the session sidebar.
4. The sessions from A never appear in B's sidebar, regardless of how long you wait.

Confirming it is a read-path issue, not a write-path issue: sessions created within an instance appear immediately in that instance's own sidebar. Restarting instance B causes it to correctly load all sessions including those written by A.

Expected behavior

Either: (a) the session sidebar polls or watches local storage and updates when new sessions appear, or (b) there is a manual refresh affordance — a button, menu item, or keyboard shortcut — to reload the list.

Actual behavior

The session list is populated once at startup and never re-read from storage. Sessions written by other instances are invisible until the current process is restarted. No refresh affordance exists.

(Cmd+R — the natural candidate — instead exits Code mode and starts a new Chat session; see #67514.)

Notes on related issues

• #25032, #22030: Those describe sessions-index.json not being written correctly (write-path failure). This is different: the index is written correctly by other instances; the bug is that the Desktop UI never re-reads it after startup (read-path failure).
• #59641 and similar cross-surface sync requests: Those are feature requests for syncing sessions across different clients (CLI, Desktop, web). This is a bug: the data already exists on disk in the expected location; the UI simply does not re-read it.
• #62620: The CI monitoring panel has the same "state cached at session start, no refresh" pattern — suggesting this may be a systemic architectural issue rather than an isolated one.