fix(preview): transfer recordings to the agent environment

[maria-rcks]

Preview recordings previously returned a desktop-local path that remote agents could not read. Agent-requested recordings now transfer the finished encoded file once through the existing signed binary upload endpoint, then return a server-local path; transfers are capped at 50 MiB and the desktop copy is retained.

Verified with real Electron recording through MCP, an authenticated connection between separate desktop/server processes and state directories on one Linux host, and matching SHA-256 hashes for the desktop and server files. The 1280×800, 17.8-second mostly static example transferred 66,086 bytes and played through without errors or dropped frames; moving content will produce larger files. Web/server typechecks and focused recording, upload, and broker tests pass. The simplified revision passed 46 focused server tests and another real MCP recording transfer: its 15,095-byte server file matched the desktop SHA-256.

Written with gpt-5.6-sol in Codex.

Note

Transfer preview recordings from desktop to agent environment

• Changes the preview recording-stop handler to ask the desktop to transfer the saved recording, then claims the uploaded attachment into a thread-scoped server path instead of returning the raw desktop artifact.
• Adds uploadBrowserRecording in browserRecordingUpload.ts to upload finalized browser recordings once to the environment with a bounded 120-second deadline, rejecting blobs over 50 MiB and mapping deadline/transfer failures to typed errors.
• Adds stopBrowserRecordingForUpload in browserRecording.ts so concurrent and repeated stop requests for one tab share a single upload promise.
• Adds four typed error classes (PreviewAutomationRecordingTransferError, PreviewAutomationRecordingDesktopUpdateRequiredError, PreviewAutomationRecordingTooLargeError, PreviewAutomationRecordingDeadlineExpiredError) in previewAutomation.ts with fixed public messages and the remote response retained as cause.
• Risk: recording-stop now requires the preview MCP capability and a 120-second transfer wait; older desktop clients without transfer support produce PreviewAutomationRecordingDesktopUpdateRequiredError instead of returning a local artifact.

^{Macroscope summarized af49c30.}

Summary by CodeRabbit

• New Features

  • Preview recordings can be transferred to the agent environment after stopping, with the local file path returned.
  • Concurrent stop requests share a single upload.
  • Recording errors now distinguish outdated desktop clients, oversized recordings, expired transfers, and upload failures.

• Bug Fixes

  • Recording transfers handle completed and incomplete uploads more reliably.
  • Desktop recordings remain available when environment transfer fails.

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR introduces a cross-client/server recording-transfer workflow and changes the default recording-stop result to an environment-local uploaded file. It also carries an unresolved high-severity concurrency concern around overlapping stops and in-flight uploads.

^{Adjust the Minimum Blocking Severity for this repo — including turning it Off — in Settings. You can add or adjust custom eligibility rules. Learn more.}

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📥 Commits

Reviewing files that changed from the base of the PR and between b76b067 and af49c30.

📒 Files selected for processing (6)

• apps/server/src/mcp/PreviewAutomationBroker.test.ts
• apps/server/src/mcp/PreviewAutomationBroker.ts
• apps/server/src/mcp/toolkits/preview/handlers.test.ts
• apps/server/src/mcp/toolkits/preview/handlers.ts
• apps/web/src/browser/browserRecordingUpload.ts
• packages/contracts/src/previewAutomation.ts

💤 Files with no reviewable changes (2)

• packages/contracts/src/previewAutomation.ts
• apps/web/src/browser/browserRecordingUpload.ts

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📝 Walkthrough

Walkthrough

Preview recording stop now uploads recordings through the scoped thread, classifies transfer failures, validates uploaded attachments, and claims the retained file in the server attachment store.

Changes

Preview recording transfer

Layer / File(s)	Summary
Recording transfer contract packages/contracts/src/previewAutomation.ts, apps/server/src/mcp/PreviewAutomationBroker.ts, apps/web/src/components/preview/previewAutomationErrors.ts, apps/server/src/mcp/PreviewAutomationBroker.test.ts	Adds dedicated recording transfer errors and timeout configuration. The broker and host serialization expose these errors with thread context.
Browser recording save and upload apps/web/src/browser/browserRecording.ts, apps/web/src/browser/browserRecordingUpload.ts, apps/web/src/browser/browserRecording.test.ts	Recording finalization stores the blob. Concurrent upload stops share one upload. Upload failures receive typed size, deadline, and transfer errors.
Preview stop upload wiring apps/web/src/components/preview/PreviewAutomationHosts.tsx, apps/server/src/mcp/toolkits/preview/tools.ts	Preview recording stop transfers the saved recording when requested and passes the scoped thread reference to the upload helper.
Server-side recording claim apps/server/src/mcp/toolkits/preview/handlers.ts, apps/server/src/mcp/toolkits/preview/handlers.test.ts	The server requests transfer, validates attachment identifiers and file sizes, supports repeated claims, and returns the retained recording path. Tests cover concurrent claims, incomplete uploads, traversal identifiers, and legacy responses.

Estimated code review effort: 4 (Complex) | ~45 minutes

Merge Risk: 🟡 Moderate · up to af49c

A failed recording transfer can leave server-side recording attachments behind without being claimed or removed. This should be resolved before merge to avoid accumulating orphaned uploaded files.

Sequence Diagram(s)

sequenceDiagram
  participant PreviewAutomationHosts
  participant AttachmentEnvironment
  participant preview_recording_stop
  participant claimPreviewRecording
  participant AttachmentStore
  PreviewAutomationHosts->>AttachmentEnvironment: Upload saved recording with scoped thread reference
  AttachmentEnvironment-->>PreviewAutomationHosts: Return uploaded attachment ID
  PreviewAutomationHosts->>preview_recording_stop: Request recording stop with transfer enabled
  preview_recording_stop->>claimPreviewRecording: Validate transfer response
  claimPreviewRecording->>AttachmentStore: Claim and rename pending file
  AttachmentStore-->>claimPreviewRecording: Return final recording path

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Suggested reviewers: juliusmarminge

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 40.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 11 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
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.
Title check	✅ Passed	The title clearly and concisely describes the main change: transferring preview recordings to the agent environment.
Description check	✅ Passed	The description explains what changed, why it changed, verification performed, size limits, compatibility behavior, and risk. It does not use the template headings or include the checklist, but it rem…

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Actionable comments posted: 4

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Inline comments:
In `@apps/server/src/mcp/toolkits/preview/handlers.ts`:
- Around line 171-179: Increase the timeout passed to invokeTargeted for
recordingStop beyond the 110-second upload timeout plus finalization and
response-handling overhead, and ensure claimPreviewRecording is also bounded by
an appropriate deadline if required. Preserve the existing preview capability
check and recording-claim flow.

In `@apps/web/src/browser/browserRecording.ts`:
- Line 712: Separate the onSaved callback handling from the
bridge.recording.save try block in the recording save flow. Keep local save
failures wrapped as BrowserRecordingOperationError("save-artifact") and convert
callback/upload failures from onSaved into
PreviewAutomationRecordingTransferError, preserving the transfer-specific error
classification.

In `@apps/web/src/browser/browserRecordingUpload.ts`:
- Around line 52-55: Update the transfer-failure branch in
runAttachmentUploadCycle to await attachmentEnvironment.remove for the returned
attachmentId before throwing. Ensure cleanup failures do not replace or obscure
the original transfer error, and preserve the existing error details for failed
uploads.

In `@apps/web/src/components/preview/PreviewAutomationHosts.tsx`:
- Around line 729-737: Update the recording-stop flow around
stopBrowserRecording so transfer state and the resulting uploadedAttachmentId
are stored on the active recording rather than in request-local state, allowing
coalesced transfer requests to share the in-flight transfer result. If a
non-transfer stop is already active, reject subsequent transfer requests instead
of returning an untransferred artifact; preserve existing behavior for
compatible coalesced requests.

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📒 Files selected for processing (8)

• apps/server/src/mcp/toolkits/preview/handlers.test.ts
• apps/server/src/mcp/toolkits/preview/handlers.ts
• apps/server/src/mcp/toolkits/preview/tools.ts
• apps/web/src/browser/browserRecording.test.ts
• apps/web/src/browser/browserRecording.ts
• apps/web/src/browser/browserRecordingUpload.ts
• apps/web/src/components/preview/PreviewAutomationHosts.tsx
• packages/contracts/src/previewAutomation.ts

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