fix(pi): notify review URL in RPC sessions - #1407

Thanks for the careful writeup on both the issue and the PR. The diagnosis is right: ctx.mode is the documented discriminator (ExtensionMode = "tui" | "rpc" | "json" | "print", required, and hasUI is true in both TUI and RPC so it cannot stand in for it). The one-line change typechecks and does fix the submit_plan and archive paths.

Three things before this can land.

1. It probably does not fix the three commands Pi Web RPC sessions do not show the Plannotator review URL #1406 names. apps/pi-extension/index.ts:182-194 has a second, independent gate:

   function sessionOpenedMessage(label: string, url: string): string {
   if (!isRemoteSession()) return ${label}. You can keep chatting while it runs.;

called at index.ts:659, :958 and :1048 for /plannotator-review, /plannotator-annotate and /plannotator-last. Its own comment says the after-turn notify inside openBrowserForServer "fires too late to render". So under RPC those three still show a URL-less message. Could you check in a real Pi Web session whether the notify renders there, and extend sessionOpenedMessage if it does not?

2. New stale-ctx exposure. ctx.mode is a guarded getter that throws after session replacement, which this repo documents at apps/pi-extension/current-pi-session.ts:40-66 and wraps in isCtxAlive(). Today the local browser-opened path reads no ctx property at all; after this change ctx.mode is read on every call. Via startBrowserDecisionSession that turns into misleading console.error noise (plannotator-browser.ts:266-272), and via openBrowserAndWait there is no catch, so an archive open that used to succeed now answers request.respond({ status: "error" }) at plannotator-events.ts:429. Please guard the read.

3. The test spawns a real process. process.execPath is not in NOOP_BROWSER_VALUES (server/network.ts:17), so network.ts:341-351 runs spawn(, ["http://localhost:4321"], { detached: true }) on macOS and Linux CI. The file header promises these tests never spawn a browser. I know the obvious alternative is worse (a sentinel BROWSER with PLANNOTATOR_REMOTE=0 falls through to resolveUseGlimpse, which reads the real ~/.plannotator/config.json), so the cleaner fix is a seam: extract a pure predicate like shouldAnnounceUrl(mode, isRemote, opened) and test that with no env mutation and no spawn.

Heads up that #1184 (open) rewrites this exact hunk to notify unconditionally, which covers RPC, Codex desktop and any future host without reading ctx.mode at all. That is the same argument your issue makes one host later, and it is probably where this should converge. Worth syncing with that PR rather than both of you landing on the same four lines.

AI-assisted (Claude) under maintainer direction.