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

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Summary

Implement client-side deferred commit strategy to avoid hammering RERUM while preserving editing UX.

Scope

• Queue local operations and coalesce by line.
• Flush on important moments: line switch, page switch, explicit save, user leave.
• Flush on long debounce idle window (8-15s).
• Force flush max age window (45-60s).
• Best-effort flush on visibility hidden or unload.
• Render statuses: local draft, syncing, persisted, conflict.

Acceptance Criteria

• Typing does not trigger per-keystroke durable save.
• Important events trigger immediate flush.
• Long-idle and max-age rules flush as expected.
• Stale data is not lost on closed sessions or dropped connections.
• User sees durable status transitions.

Dependencies

• Depends on TPEN-services draft intake issue.
• Aligned to contract in TPEN-services docs/collaboration/websocket-collaboration-contract.md.

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Dependency map for execution planning:

Depends on:

• Collab Phase 3: Draft Buffer API and Operation Intake for Deferred Persistence TPEN-services#510
• Collab Phase 2: Realtime Client and Presence UI (No Save Behavior Change Yet) #555
• Collaboration Contract v1.0 Ratification for Services, Interfaces, and RERUM TPEN-services#512

Blocks:

• Collab Phase 7: Conflict Resolution UX and Collaboration Observability Dashboards #557

Related to:

• Collab Phase 5: Durable Flush Worker from Drafts to RERUM with Conflict Acks TPEN-services#511

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Phase Documentation Addendum

• This phase implements deferred commit policy aligned to Contract section 8.
• Required validation: important-moment flush, long debounce flush, max-age flush, best-effort unload flush.
• Exit artifacts: timeline traces for flush triggers and UI state transitions.

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Phase Documentation Addendum

• This phase implements deferred commit policy aligned to Contract section 8.
• Required validation: important-moment flush, long debounce flush, max-age flush, best-effort unload flush.
• Exit artifacts: timeline traces for flush triggers and UI state transitions.