docs(gc-handoff): final probe count for #7803, and how to rebuild the experiment

[proggeramlug]

Follow-up to #7989, which merged while the last two background sweeps were still
running. Doc-only, same file.

• The marker-instrumented probe finished: 12 of 12 seeds passed, not the
  10 of 10 recorded at merge time. Seed 11's marker log reads empty only because
  a disk-pressure cleanup of mine deleted its stderr while that run was still in
  flight — recorded rather than quietly dropped.
• Adds a "Rebuilding this from scratch" section. The worktree and its
  CARGO_TARGET_DIR were both deleted by whatever sweeps
  /Users/amlug/projects/perry/wt-* on this box, while a sweep was still
  running, so the next person gets no artifacts — only the recipe. It includes
  the one non-obvious requirement: PERRY_NO_AUTO_OPTIMIZE=1 is not optional,
  because the auto-optimizer relinks the runtime without diagnostics and
  removes the [gc-fromspace-protect] evidence the analysis depends on.

No version bump.

Summary by CodeRabbit

• Documentation
  • Updated experiment results to report 12 successful runs.
  • Documented the missing marker log for seed 11 despite its successful completion.
  • Added instructions for rebuilding the environment, reproducing the issue, and running the 16-seed fuzz sweep.
  • Included required environment settings and timing/resource guidance.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: aeb699b3-d930-4b7c-b401-b3c5f2b98b17

📥 Commits

Reviewing files that changed from the base of the PR and between 55fd197 and 2520c4a.

📒 Files selected for processing (1)

• gc-handoff/ZOD-NOTES.md

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📝 Walkthrough

Walkthrough

The Zod GC handoff notes now report 12 successful phase-probe runs and explain the missing seed-11 log. They also document a complete rebuild and reproduction procedure, including the 16-seed fuzz sweep and diagnostic requirements.

Changes

Zod GC handoff documentation

Layer / File(s)	Summary
Phase-probe results gc-handoff/ZOD-NOTES.md	The recorded result changes from 10 to 12 successful seeds. The notes explain that cleanup deleted seed 11’s stderr while the run was active, although the run exited successfully.
Rebuild and reproduction procedure gc-handoff/ZOD-NOTES.md	The notes add steps for worktree setup, release builds, dependency installation, corpus compilation, the filed seed-1 condition, the 16-seed fuzz sweep, required environment variables, and preservation of from-space evidence.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Possibly related PRs

• PerryTS/perry#7317: Provides the seeded GC scheduling and 16-seed fuzz-sweep tooling referenced by the updated notes.
• PerryTS/perry#7989: Updates the same notes file with results from the Zod GC-handoff investigation.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch gc/7803-zod-notes-followup

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