app: each new chat keeps ~10 files open in the engine for the life of the app (macOS soak) #2471

Measured on macOS 15.6 / Apple Silicon during a 58-minute soak (2026-11-06). Engine: app/v3 3a6aa31 + #2466. Desk: main 0f1974872.

What happens: each new chat leaves codeaf app holding about 10 more open files for as long as the app runs. The files are the project directory, .cell, transcript.jsonl, meta, lock, presence, card and told files. The seeded long chat holds 7.

• During the steady phase, three tool turns each ran in a new chat. Engine fds went 59 → 74 → 85 → ~96, flat between turns.
• Over the same phase, per 10 min: engine footprint +5.6 MB, threads +0.5, wakeups +1.7/s.
• Desk processes (app, WebContent, WebKit GPU) stayed flat over the same phase.

Likely cause: a chat whose window is open is never released (app.go:79-82). Each chat also keeps its presence heartbeat (5 s / 7 s, session/taskpresence.go). On macOS, fsnotify's kqueue backend holds a handle per watched file in each session folder.

Why it matters: growth is bounded by the number of chats opened in a session, not by time. A long-lived app that opens many chats keeps accumulating fds and per-chat timers.

Possible direction: close an idle chat's files and watches when it isn't shown and has no live turn. Keep the presence heartbeat, which #2065 keeps on purpose; only the watch and the open files would go.

Raw data: soak-60s.jsonl and soak-turn-{1,2,3}.jsonl from the push (sampler: libproc rusage per pid).

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