(renderer): a transcript-activity message before app.js loads throws 'activePtyIds is not defined'

[devsuitup]

A session-transcript-activity message that arrives before app.js has run throws in the renderer:

[renderer:3] :136 Uncaught Error: activePtyIds is not defined

Seen once at startup on an isolated instance whose HOME had live sessions writing transcripts during load (2026-10-02, at #414's head).

Cause:

• public/local-transcript-adapter.js:135 registers window.api.onSessionTranscriptActivity(onLocalTranscriptActivity) at top level.
• That script loads before app.js (index.html:156 vs :163).
• The handler reads activePtyIds (local-transcript-adapter.js:88, sub-agent path :102), which is declared at public/app.js:127.
• main.js sends the message from the projects watcher, which starts right after createWindow() with no renderer-readiness gate.
• :136 is the ipcRenderer.on('session-transcript-activity', …) line of preload.js plus Electron's sandbox wrapper offset.

Not a regression:

• The same text reproduces on v0.0.85 and d9baecd.
• To reproduce deterministically, delay only app.js by 3 s with protocol.handle('file'), send the message every 200 ms, and reload: 14 errors.
• Plain launches on an idle machine do not hit it, 3 launches each.
• The registration dates from 317b04b ((session-state): local-transcript adapter for sessions launched outside the app #269).

Supposed impact (not measured): one dropped busy signal for that session. The next send, at most 1 s later, works once app.js has loaded.

Fix direction: register the listener from app.js once its state exists, or guard the handler until the renderer is ready.