fix(snapshot): add phase5 runtime verification and loose-object compaction

[riatzukiza]

Issue for this PR

Closes #74

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Adds a debug snapshot verify churn harness for Phase 5 runtime validation and uses its findings to harden cleanup behavior. Cleanup now compacts high loose-object growth with git repack -d -l and keeps prune fallback when counts remain elevated.

How did you verify your code works?

• Ran bun run typecheck from packages/opencode.
• Ran bun test test/snapshot/snapshot.test.ts from packages/opencode.
• Ran OPENCODE_CONFIG_CONTENT='{"$schema":"https://opencode.ai/config.json","snapshot":true}' bun run packages/opencode/src/index.ts debug snapshot verify --iterations 12 --concurrency 6 --cleanup-every 3.

Screenshots / recordings

N/A (non-UI change).

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

See CONTRIBUTING.md for details.

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/snapshot-phase5-verify

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}