Collab Phase 2: Realtime Client and Presence UI (No Save Behavior Change Yet)

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Summary

Implement websocket client integration and collaborator presence UI without changing persistence behavior yet.

Scope

• Add websocket client service with reconnect and token refresh handling.
• Join project and page rooms for active editing context.
• Send and render presence/cursor/selection events.
• Keep current save endpoints unchanged in this phase.
• Gate by feature flag.

Acceptance Criteria

• Collaborator presence appears in active page.
• Cursor updates are visible with acceptable latency.
• Existing save behavior remains unchanged when feature flag on.
• Full disable when feature flag off.

Dependency

• Depends on TPEN-services websocket skeleton issue.

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Dependency map for execution planning:

Depends on:

• Collab Phase 1: Websocket Server Skeleton, Auth, and Presence Rooms TPEN-services#509
• Collaboration Contract v1.0 Ratification for Services, Interfaces, and RERUM TPEN-services#512

Blocks:

• Collab Phase 4: Deferred Commit Engine with Important-Moment and Long-Debounce Flush #556

Related to:

• Collab Phase 3: Draft Buffer API and Operation Intake for Deferred Persistence TPEN-services#510

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Phase Documentation Addendum

• This phase is presence-only UX and transport client behavior and must not alter save semantics.
• Required validation: reconnect, token refresh handling, cursor/selection rendering consistency.
• Exit artifacts: presence UX screenshots and reconnect trace.