feat: strengthen browser surface protocol

[glittercowboy]

Summary

• Add browser input frame/control metadata, acknowledgements, and transport status messages.
• Add preview bridge access messages for local-direct and preview-origin browser flows.
• Document browser input safety, transport status, and bridge access contracts.

Verification

• go test ./...

Dependency Order

• Merge and tag this protocol module before daemon and cloud-app consumer PRs.

Summary by CodeRabbit

• New Features
  • New input acknowledgment system providing feedback on control requests with rejection reasons
  • Real-time transport status monitoring including queue depth, dropped frame counts, and performance metrics
  • Enhanced frame and viewport metadata tracking for improved rendering accuracy
  • Secure bridge access lifecycle with time-limited, grant-based authorization

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

Walkthrough

The pull request extends the browser shared-session protocol with new message types and enriches existing schemas. New message types include browserUserInputAck for input acknowledgement, browserTransportStatus for transport health metrics, and browserBridgeAccessOpen/Opened/Close for bridge access lifecycle management. Several existing message types (browserFrame, browserUserInput, browserControlClaim/Release) gain optional fields for frame references, viewport metadata, and coordinate/render information. The Go implementation is updated to parse these new message types and define corresponding structs.

Changes

Cohort / File(s)	Summary
Protocol Documentation PROTOCOL.md	Defines new message schemas (browserUserInputAck, browserTransportStatus, browserBridgeAccessOpen/Opened/Close) and extends existing messages (browserFrame, browserUserInput, control messages) with optional versioning, viewport, coordinate space, and rendered geometry metadata.
Message Envelope Parser envelope.go	Adds five new cases to the payloadForType switch to unmarshal the new browser message types (...UserInputAck, ...TransportStatus, ...BridgeAccessOpen/Opened/Close) into their corresponding payload structs.
Message Type Definitions messages.go	Introduces message type constants for new messages, adds owner/kind/coordinate-space/rejection-reason constants, and defines new structs (BrowserUserInputAck, BrowserTransportStatus, BrowserBridgeAccessOpen/Opened). Extends BrowserSessionOpen, BrowserFrame, BrowserControlClaim/Release, and BrowserUserInput with optional metadata fields; updates BrowserBridgeAccessClose to carry grant/preview identifiers and reason.
Test Coverage messages_test.go	Expands TestEnvelopeRoundTrip to cover new message types and additional struct fields, including control versions, transport metrics, and rendered geometry. Adds TestBrowserUserInputMetadataJSONNames to verify marshaled JSON property names for BrowserUserInput metadata fields.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• Add shared browser session protocol #30: Directly related—introduces browser session message types and structures that this PR extends with new fields and lifecycle messages.
• feat: add terminal protocol messages #22: Both PRs add new protocol message families and update the same payloadForType switch and messages.go registration patterns.
• Add remote preview protocol messages #20: Both PRs modify protocol parsing logic in envelope.go to register new message-type-to-payload mappings.

Poem

🐰 New messages hop across the wire,
Input acks and status higher,
Bridge access opens, closes clean,
The finest protocol we've seen! ✨

🚥 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 'feat: strengthen browser surface protocol' accurately reflects the main changes: extending the browser protocol with new message types, metadata fields, and safety/transport contracts.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/unified-web-surface-protocol

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