fix: send JSON:API Accept on GitHub App manifest setup

[essinghigh]

Clicking "Create or replace with GitHub" always failed with 406 "The Accept header must allow application/vnd.api+json".

Root cause: the frontend sent Accept: application/json on /admin/github-app/manifest/setup. The endpoint returns a vnd.api+json document, so the Accept gate rejects anything else. The endpoint itself negotiates its JSON body on either media type, so requesting vnd.api+json satisfies both sides. One-line fix.

Tests: frontend header regression test (asserts the Accept value plus end-to-end navigation to the GitHub setup URL) and backend 200/406 contract tests for the endpoint.

Verified: frontend 534/534, github-app backend suites 14/14, typechecks clean, file lint clean, complexity zero repo-wide, lint budget passes (752/0 vs 762/0).

AI-assisted contribution via Hermes Agent (Nous Research), model muse-spark.

Summary by CodeRabbit

• Bug Fixes

  • Fixed GitHub App setup in the admin area so requests are accepted correctly by the API.
  • Successful setup now redirects administrators to the GitHub authorization page as expected.

• Tests

  • Added coverage for GitHub App manifest setup requests, content negotiation, authorization URL handling, and redirect behavior.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Advanced

Run ID: 9b638946-5b22-4ac9-a8fa-f42e1c228215

📥 Commits

Reviewing files that changed from the base of the PR and between f23734e and 88d2b7b.

📒 Files selected for processing (3)

• backend/tests/api/admin_github_app_manifest.test.ts
• frontend/src/views/AdminGitHubApp.tsx
• frontend/tests/admin-github-app.test.tsx

Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

The backend tests define the manifest setup Accept contract. The frontend sends the JSON:API media type and redirects to the returned GitHub authorization URL. Frontend tests verify the request header and redirect behavior.

Changes

GitHub App manifest setup

Layer / File(s)	Summary
Manifest endpoint contract backend/tests/api/admin_github_app_manifest.test.ts	The tests create an authenticated site-admin request, accept application/vnd.api+json, and reject application/json with status 406.
Frontend manifest request frontend/src/views/AdminGitHubApp.tsx, frontend/tests/admin-github-app.test.tsx	The view sends the JSON:API Accept header. The test verifies the header and redirect to the authorization URL.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to 88d2b

The manifest setup request now matches the endpoint’s content-negotiation contract, preventing the prior 406 response during GitHub App setup.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: sending the JSON:API Accept header for GitHub App manifest setup.
Description check	✅ Passed	The description explains the failure, root cause, fix, tests, verification results, and AI assistance disclosure. It does not reproduce the template headings or explicitly check each checklist item, b…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches 💡 1

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• Commit unit tests in branch fix/github-app-accept-header

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_{A rabbit checks the headers bright
JSON:API guides the flight
GitHub opens one shining door
Tests confirm the path once more
Hoppy code now lands just right}

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