[BUG] claude://resume duplicates a session already open as a native Desktop tab; no deep link to focus an existing native session

Summary

claude://resume?session=<cli-session-id> imports a CLI session by minting a new Desktop session whose id is hardcoded to local_<cliSessionId>, and de-duplicates purely on that id key. As a consequence:

1. If the same CLI session is already open as a native Desktop Code tab (created inside Desktop, not via an earlier resume import), the deep link cannot find it and creates a duplicate tab — a snapshot fork of identical content that no longer stays in sync with the live native session.
2. There is no deep link (or any documented URL) to focus an existing native Desktop session by id, so external integrations can only ever activate the app, never navigate to a specific native tab.

This is adjacent to #79309 (Desktop "Open in terminal" also spawns a new session) but on the inbound external→Desktop path.

Environment

• Claude Desktop 1.24012.1 (macOS)
• claude:// URL scheme, resume route

Steps to reproduce

1. In Claude Desktop, open a Code session natively (New → Code). Note its content.
2. Find that session's CLI session id (the UUID in the transcript filename under ~/.claude/projects/<project>/<uuid>.jsonl, which Desktop stores as cliSessionId in ~/Library/Application Support/Claude/claude-code-sessions/<account>/<org>/local_*.json).
3. Trigger open "claude://resume?session=<uuid>".

Expected: the existing native tab is focused.
Actual: a second "General coding session" tab appears with duplicated content; the original native tab is untouched.

Root cause (from the shipped bundle)

importCliSession de-dupes on a key convention, not on the cliSessionId property:

const r = `${LOCAL_SESSION_PREFIX}${e}`;      // "local_" + cliSessionId
if (this.sessions.get(r)) {                    // key lookup only
    this.unarchiveSession(r);
    return r;                                   // → focuses the tab
}
// else: read transcript, create a new session whose id is set to r

• A session created by resume gets id = local_<cliSessionId>, so a second resume with the same id hits the key and focuses — this is why re-importing works.
• A native Desktop session gets id = local_<random-uuid>; its cliSessionId lives only as a stored property. The key local_<cliSessionId> is never present, so the lookup always misses and duplicates.

The de-dup data (cliSessionId) is already persisted on every session record — the lookup simply doesn't consult it.

Suggested fix (either one)

1. In importCliSession, before creating a new session, also look up any existing session (native included) whose stored cliSessionId === e; if found, focus it instead of importing.
2. Or expose a dedicated focus route, e.g. claude://claude-code-desktop/focus?cliSessionId=<uuid>, that navigates to an existing native session without importing.

Either would let external tools (companion apps, launchers, hardware remotes) deep-link users to the actual running session rather than a stale snapshot copy.

Context

Building a companion app that surfaces active Claude Code sessions and offers "open this session in Desktop". resume works great for headless / CLI-only sessions (gives them a UI), and re-focusing an already-imported session works — but native Desktop sessions can only be app-activated, and blindly calling resume on them silently duplicates. A focus-by-cliSessionId path would close the gap.

{"type":"last-prompt","lastPrompt":"No need to have any button groups","leafUuid":"122a22b0-dea2-4d4c-8be2-59048823dc17","sessionId":"4adbe4d1-233d-4a1b-bb39-cadecce54f5a"}
{"type":"custom-title","customTitle":"Session title icon buttons","sessionId":"4adbe4d1-233d-4a1b-bb39-cadecce54f5a"}
{"type":"mode","mode":"normal","sessionId":"4adbe4d1-233d-4a1b-bb39-cadecce54f5a"}