(MOT-4277) fix(harness): bootstrap benchmark history branch

[ytallo]

Refs MOT-4277

Summary

• create the remote gh-pages branch before benchmark-action stores the first metrics
• use an empty Git commit so initialization does not modify or switch the workflow checkout
• make branch creation idempotent and safe when another publisher wins the creation race
• remove the late bootstrap path that could never run after the first benchmark action failed

Root cause

The first publisher run successfully downloaded the compact metrics and full execution artifacts, but benchmark-action tried to fetch gh-pages before that branch existed. The job stopped before reaching the workflow's existing orphan-branch fallback, so no history or Pages artifact was published.

Validation

• exercised branch creation and idempotence against a temporary bare Git remote
• verified invalid branch names are rejected
• python3 -m py_compile .github/scripts/bootstrap_benchmark_history.py
• git diff --check

Summary by CodeRabbit

• New Features

  • Automated benchmark history initialization now creates the publishing history when it is missing.
  • Benchmark publishing can reuse existing history without recreating or overwriting it.

• Bug Fixes

  • Improved reliability when multiple publishing processes attempt initialization simultaneously.
  • Invalid history branch names are rejected with a clear error.

• Tests

  • Added coverage for branch creation, idempotent behavior, and input validation.

[vercel]

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Project	Deployment	Actions	Updated (UTC)
workers	Ready	Preview	Jul 30, 2026 10:04am
workers-tech-spec	Ready	Preview	Jul 30, 2026 10:04am

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 82f2434c-7560-4370-9ee9-6c993ee2ea7a

📥 Commits

Reviewing files that changed from the base of the PR and between 86c80f7 and ea743cb.

📒 Files selected for processing (3)

• .github/scripts/bootstrap_benchmark_history.py
• .github/scripts/tests/test_bootstrap_benchmark_history.py
• .github/workflows/harness-e2e-benchmark.yml

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📝 Walkthrough

Walkthrough

A new script initializes a missing remote gh-pages benchmark history branch with an empty commit. Tests cover idempotency and invalid names, while the benchmark workflow invokes the script and simplifies history checkout and publishing.

Changes

Benchmark history initialization

Layer / File(s)	Summary
Remote branch bootstrap script .github/scripts/bootstrap_benchmark_history.py	Adds Git helpers, remote branch detection, empty-commit creation, race-safe pushing, CLI parsing, and status reporting.
Bootstrap behavior tests .github/scripts/tests/test_bootstrap_benchmark_history.py	Adds hermetic repository tests for empty branch creation, idempotency, and invalid branch-name validation.
Workflow bootstrap and checkout integration .github/workflows/harness-e2e-benchmark.yml	Runs the bootstrap script before publishing, checks out gh-pages directly, and removes inline branch initialization.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant GitHubActions
  participant BootstrapScript
  participant GitRemote
  GitHubActions->>BootstrapScript: Run bootstrap_benchmark_history.py
  BootstrapScript->>GitRemote: Check refs/heads/gh-pages
  GitRemote-->>BootstrapScript: Return branch status
  BootstrapScript->>GitRemote: Push empty commit if missing
  GitRemote-->>BootstrapScript: Confirm branch creation
  GitHubActions->>GitRemote: Checkout gh-pages

Loading

Possibly related PRs

• iii-hq/workers#637: Refactors the same workflow’s gh-pages benchmark-history initialization.

Poem

A bunny found a branch asleep,
And planted commits neat and deep.
The workflow hops, the pages gleam,
Tests guard each Git command and stream.
“No duplicate burrows!” cheers the hare.

✨ 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 fix/harness-e2e-gh-pages-bootstrap

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[github-actions]

skill-check — worker

0 verified, 49 skipped (no docs/).

Layer	Result
structure	✓
vale	✓
ai	✓
render	✓

Four for four. Nicely done.