Isolate agent process groups from Controller

[germanescobar]

Summary

• launch Anita, Codex, and Claude in isolated POSIX sessions/process groups
• signal the complete isolated agent tree during cancellation and forced shutdown
• reap active isolated agents when Controller exits normally
• add regression coverage for process-group isolation and shutdown cleanup

Why

An agent tool or test runner can signal its entire process group. Agent CLIs previously shared Controller's process group, so one of those signals could terminate the Electron host as well. macOS then recorded a normal process exit rather than a crash, which explains why no crash report was generated.

Verification

• npm run build
• npx tsc -p server/tsconfig.json --noEmit
• focused and adjacent server tests: 32/32 passing
• full suite: 1044/1046 passing; the two failures are pre-existing date-sensitive visited-state tests whose September 4-5 fixtures are outside the TTL on September 16

[germanescobar]

@codex review

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-16T16:45:05.176895Z	28b8e8c	Manual request

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[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 28b8e8c27c

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[chatgpt-codex-connector]

Clean up isolated agents on termination signals

When Controller is stopped with SIGINT or SIGTERM—such as Ctrl-C in the documented dev flow, whose wrapper forwards both signals in scripts/dev-server-with-port-bump.mjs—Node performs the default signal termination without emitting the exit event, so this callback does not run. Since this commit moves agent CLIs into detached process groups, they no longer receive that terminal/service signal and can continue running tools after Controller exits; install explicit SIGINT/SIGTERM handlers that synchronously stop the runtimes before re-raising the signal or exiting.

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