Harden git test fixtures against auto-gc flakes

[fgilio]

Summary

Addresses the parallel-shard flake in #133, where CI failed mid-test with error: bad tree object HEAD — loose objects vanishing from a fixture repo's object store during rapid commit loops.

• Rules out cross-worker deletion: every temp-dir cleanup glob in the suite was audited and is PID-scoped, leaving git auto-gc/auto-maintenance racing object writes as the remaining suspect.
• Disables gc.auto/maintenance.auto twice over: via GIT_CONFIG_* env in phpunit.xml (covers every git invocation from test processes, including ad-hoc git init repos) and baked into the RepoTemplate .git/config (covers copied fixtures even when git runs in a child process with a sanitized environment).
• Adds forensics on recurrence: runTestRepoCommand() now appends a git count-objects -v + git fsck snapshot to the exception, so any future failure shows what survived in the object store.

Gotcha documented along the way

PHPUnit coerces <env value="false"/> into an empty string, so the new env entries use "0". The pre-existing commit.gpgsign entry has been exporting an empty value all along — git parses empty as boolean false, so it works, but it silently shadows file-scope values for the same key. Noted in phpunit.xml and tests/CLAUDE.md.

Testing

• New regression tests in tests/Unit/Helpers/InteractsWithTestRepositoriesTest.php (gc-off config on copied fixtures; forensics appended to failed repo commands)
• Core suite green under --parallel: 1655 passed
• Browser suite green: 199 passed, 1 skipped
• PHPStan and Pint clean

Refs #133 — suggest closing it after a few more sharded CI runs pass, since a flake can't be proven dead in one run.

🤖 Generated with Claude Code

https://claude.ai/code/session_01HVdCTd166nSKuhBsnKePM9

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Generated by Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Improved reliability of test repository setup by disabling automatic Git maintenance during parallel runs.
  • Repository command failures now include extra Git object-store diagnostics, making issues easier to troubleshoot.

• Documentation

  • Updated test guidance to reflect the new repository maintenance and failure-diagnostics behavior.

• Tests

  • Added coverage for Git configuration defaults and enhanced failure reporting.

[coderabbitai]

Caution

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📝 Walkthrough

Walkthrough

This PR disables Git auto-gc and auto-maintenance in test fixture repositories via PHPUnit environment variables and RepoTemplate initialization, adds object-store diagnostics (git count-objects, git fsck) appended to exceptions from failed repo commands, and adds documentation and tests validating both behaviors.

Changes

Fixture Repo Maintenance and Diagnostics

Layer / File(s)	Summary
Disable auto-gc via env and template init phpunit.xml, tests/Helpers/RepoTemplate.php	Adds GIT_CONFIG_KEY_1/2 and GIT_CONFIG_VALUE_1/2 for gc.auto/maintenance.auto in phpunit.xml (GIT_CONFIG_COUNT raised to 3), and RepoTemplate::path() sets the same config values during git init.
Append object-store diagnostics on command failure tests/Helpers/InteractsWithTestRepositories.php	runTestRepoCommand() catches RuntimeException and rethrows with appended object-store state from a new describeRepositoryObjectStore() helper running git count-objects -v and git fsck --no-progress.
Tests and docs for the above tests/Unit/Helpers/InteractsWithTestRepositoriesTest.php, tests/CLAUDE.md	New Pest tests assert gc.auto/maintenance.auto are disabled in fixture repos and that failures include object-store forensics; CLAUDE.md documents both behaviors.

Estimated code review effort: 2 (Simple) | ~12 minutes

Sequence Diagram(s)

sequenceDiagram
    participant Test
    participant InteractsWithTestRepositories
    participant Git

    Test->>InteractsWithTestRepositories: runTestRepoCommand()
    InteractsWithTestRepositories->>Git: execOrThrow(command)
    Git-->>InteractsWithTestRepositories: RuntimeException
    InteractsWithTestRepositories->>Git: describeRepositoryObjectStore() (count-objects, fsck)
    Git-->>InteractsWithTestRepositories: object store output
    InteractsWithTestRepositories-->>Test: RuntimeException with appended diagnostics

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Possibly related issues

• Flaky CI: git fixture fails with "bad tree object HEAD" under parallel Core shards #133: Disabling Git auto-gc/maintenance in fixture repos and adding failure diagnostics directly addresses the CI flake described in this issue.

Possibly related PRs

• fgilio/rfa#56: Both PRs modify the same test git-repository helper logic in tests/Helpers/InteractsWithTestRepositories.php around fixture/template setup and command execution.

Poem

A rabbit tends the git repo's soil,
No auto-gc to spoil the toil,
When commands fail, forensics appear,
Count-objects and fsck, crystal clear,
Fixture repos, calm and coiled. 🐇

Warning

Tools execution failed with the following error:

Failed to run tools: 13 INTERNAL: Received RST_STREAM with code 2 (Internal server error)

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