Let candidates record webcam or screen, not both

[mrevanzak]

Candidates now choose one capture input before recording: webcam or screen share. They cannot run both at the same time.

What changed

• Setup offers two actions: Enable camera and microphone, or Share your screen
• Choosing one replaces the other if they switch before Start
• Screen capture also attaches microphone audio when available
• If the browser ends screen sharing, capture stops and they can pick an input again
• The existing single-session upload/finalize/playback pipeline is unchanged

Testing

• Unit tests: pnpm test (154 passed)
• Playwright: 18 e2e tests passed, including a screen-only path that never shows a camera preview

  

[access-time-code-pr-reviewer]

Review Summary

This PR adds a mutually exclusive webcam-or-screen recording flow, including microphone attachment for screen capture, source-specific previews and messaging, and recovery when screen sharing ends. The existing upload and finalization pipeline remains in use, but the unauthenticated upload path can persist orphaned R2 objects before session ownership is validated.

Key Changes:

• Adds webcam and screen-share capture selection with switching before recording starts.
• Attaches microphone audio to screen recordings when available and handles screen-track termination.
• Updates recording previews, delivery messaging, recovery states, and automated coverage for both capture modes.
• Retains the existing segment upload and finalization pipeline.

Confidence Score: 5/5

Recommendation: Review findings before merge.

Rationale: The changed client flow and the upload/acknowledgement ordering are directly evidenced by the diff and identified server behavior. The storage-abuse path is a concrete security and cost risk with a clear remediation.

Special Attention

- Validate segment ownership before writing to R2, or delete the uploaded object whenever acknowledgement fails. - Exercise unauthenticated uploads with arbitrary session and segment IDs to confirm orphaned objects cannot accumulate. - Verify microphone and screen-track cleanup across permission failures, switching, and ended screen shares.

Important Files Changed

File	Overview
apps/web/src/recording/capture-inputs.ts	Acquires camera or screen streams, attaches microphone audio to screen capture, and listens for ended tracks.
apps/web/src/recording/candidate-recording-journey.tsx	Renders the mutually exclusive capture-selection, preview, recording, recovery, and delivery states.
apps/web/src/recording/live-recording.ts	Coordinates capture source state, local recording persistence, upload draining, and finalization.
apps/web/src/server/recording-upload.ts	Uploads recording segments to R2 and acknowledges them; its write-before-validation ordering creates the orphaned-object risk.
apps/web/tests/e2e/candidate-recording.spec.ts	Covers candidate recording flows, including screen-only capture and recovery behavior.

Sequence Diagram

sequenceDiagram
  participant C as Unauthenticated Client
  participant U as Recording Upload Endpoint
  participant R as R2
  participant D as Session Database
  C->>U: Upload arbitrary sessionId/segmentId
  U->>R: Write segment object
  U->>D: Acknowledge segment ownership
  alt Segment belongs to session
    D-->>U: Success
    U-->>C: Acknowledged
  else Unknown or unauthorized segment
    D-->>U: 404 / failure
    U-->>C: Error
    Note over R: Object remains orphaned
  end

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Audit history

[access-time-code-pr-reviewer]

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_{🤖 review-bot · openai/gpt-5.6-luna · standard · 143.4s · 923,118 tokens · diff: 10 files · preloaded context: 10 changed + 8 related · policy: github-pr-review, thermo-nuclear-code-quality-review · optional skills invoked: react-useeffect, vercel-composition-patterns, vercel-react-best-practices}