Add bounded warm Pi provider workers

[glittercowboy]

Summary

• Adds warm Pi worker config, identity keys, reusable worker process ownership, and bounded worker eviction.
• Routes opted-in Pi tasks through warm workers with status snapshots and socket API visibility.
• Adds warm lifecycle coverage for daemon Pi reuse, Codex AppServer provider reuse, and Claude SDK query pump reuse.

Test Plan

• go test ./...
• cd internal/pi/extension && npm test
• go build -o gsd-cloud .
• GSD_WARM_PI_WORKERS=1 go test ./tests/e2e -run TestDaemonWarmPiWorkerReusesProcessAcrossTasks -count=1
• ps -axo pid,ppid,stat,command | rg '[f]ake-pi-warm|[p]i -p --mode rpc'

Merge Order

• Single-repo daemon change. No upstream dependency.

Post-Merge Actions

• No tag or daemon release is required by this PR alone.

Summary by CodeRabbit

Release Notes

• New Features

  • Added warm Pi process reuse: long-lived Pi processes now persist between tasks for improved performance.
  • Added /workers API endpoint to monitor warm worker state and lifecycle.
  • Added configuration for warm worker idle timeout and capacity limits.
  • Added worker eviction policies based on TTL, LRU, and memory pressure.

• Documentation

  • Added implementation plan and design specification for warm Pi provider process lifecycle management.

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 5.77% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Add bounded warm Pi provider workers' directly and clearly describes the main change in the PR, which introduces warm worker pooling with lifecycle management.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/warm-pi-provider-processes-spec

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