fix(review-agent): fetch private GitHub PR diffs via API

[BashOpsDev]

Summary

Fixes #1277.

The Review Agent currently fetches pull request diffs using the diff_url returned by GitHub. For private repositories, this URL can return 404 Not Found even when the GitHub App token has permission to access the pull request through the GitHub API.

This change updates githubPrParser to fetch diffs through the GitHub Pull Requests API using the application/vnd.github.diff accept header. This allows authenticated access to PR diffs in private repositories.

Changes

• Replace direct requests to pullRequest.diff_url
• Fetch PR diffs using GET /repos/{owner}/{repo}/pulls/{pull_number}
• Request diff content via application/vnd.github.diff
• Update tests to verify API-based diff fetching

Testing

cd packages/web
yarn vitest githubPrParser

Result:

• Test Files: 1 passed
• Tests: 9 passed

Summary by CodeRabbit

• Bug Fixes
  • Updated pull request diff retrieval to use the official GitHub Pulls API endpoint with the correct diff Accept header, instead of relying on the pull request’s direct diff URL.
  • Updated the related test to verify the new API request behavior and expected parameters.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 4a3f9afa-74f4-405d-8e20-ceab02c82382

📥 Commits

Reviewing files that changed from the base of the PR and between a43e11b and fb3a212.

📒 Files selected for processing (1)

• packages/web/src/features/agents/review-agent/nodes/githubPrParser.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• packages/web/src/features/agents/review-agent/nodes/githubPrParser.ts

---

Walkthrough

githubPrParser now fetches pull request diffs through the GitHub Pulls API with the diff media type, instead of reading pullRequest.diff_url. The test was updated to match the new request shape.

Changes

Authenticated PR diff fetching via Octokit Pulls API

Layer / File(s)	Summary
Diff fetch via Octokit Pulls API packages/web/src/features/agents/review-agent/nodes/githubPrParser.ts, packages/web/src/features/agents/review-agent/nodes/githubPrParser.test.ts	githubPrParser derives owner, repo, and pull_number from the pull request, requests GET /repos/{owner}/{repo}/pulls/{pull_number} with accept: application/vnd.github.diff, and parses the returned diff string. The test asserts the updated Octokit request arguments and header.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main fix: fetching private GitHub PR diffs through the API.
Linked Issues check	✅ Passed	The parser now uses the GitHub Pulls API with a diff accept header, which addresses private-repo diff fetching in #1277.
Out of Scope Changes check	✅ Passed	The changes stay focused on the diff-fetching fix and test updates, with no unrelated functionality added.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@packages/web/src/features/agents/review-agent/nodes/githubPrParser.ts`:
- Around line 15-20: The local variable `pull_number` violates
TypeScript/JavaScript naming conventions which require camelCase for
identifiers. Rename the local variable from `pull_number` to `pullNumber` on the
line where it is assigned from `pullRequest.number`. Then in the octokit.request
call, update the parameter mapping to use `pull_number: pullNumber` to keep the
API field name in snake_case while the local variable follows camelCase
conventions.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 963e0c7a-35ed-491d-b985-0d8e52b18c72

📥 Commits

Reviewing files that changed from the base of the PR and between 26435a4 and 0f2efb5.

📒 Files selected for processing (2)

• packages/web/src/features/agents/review-agent/nodes/githubPrParser.test.ts
• packages/web/src/features/agents/review-agent/nodes/githubPrParser.ts

[BashOpsDev]

Thanks for the approval @brendan-kellam.

I can take care of the remaining failing checks. I see lint and tests are passing, and the remaining failures are the PR Gate build and Changelog Reminder. I’ll inspect the logs and add a changelog entry if required.

[BashOpsDev]

Thanks again @brendan-kellam.

I’ve updated the branch with latest main and fixed the PR Gate build issue. The build was failing because TypeScript inferred the Octokit diff response as the default pull request JSON shape, so I updated the diff parsing cast accordingly.

I verified locally:

yarn build

Result: completed successfully.

The branch is ready for re-review when you have a chance.

[brendan-kellam]

@claude add a changelog entry

[claude]

Claude finished @brendan-kellam's task in 27s —— View job

---

Adding changelog entry

• Read CHANGELOG.md
• Add entry under [Unreleased] → Fixed
• Commit and push

Added the following entry under [Unreleased] → Fixed and pushed it to fix/private-pr-diff-fetch:

Fixed the Review Agent failing to fetch pull request diffs for private GitHub repositories by fetching diffs through the GitHub Pulls API with the diff accept header instead of the diff_url. [#1352]
· fix/private-pr-diff-fetch