perf(server): avoid thread-wide scans for message projection

[juliusmarminge]

Summary

• add keyed projected-message lookup support in the projection repository
• stop loading every thread message row for each thread.message-sent projection update
• extend repository coverage for the new lookup path

Stack

• base: oxc stack #1 in this stack (codex/backend-perf-queries)

Validation

• bun run test src/persistence/Layers/ProjectionThreadMessages.test.ts src/orchestration/Layers/ProjectionPipeline.test.ts
• bun run test src/orchestration/Layers/ProjectionSnapshotQuery.test.ts src/checkpointing/Layers/CheckpointDiffQuery.test.ts src/persistence/Layers/ProjectionThreadMessages.test.ts src/orchestration/Layers/ProjectionPipeline.test.ts src/orchestration/Layers/OrchestrationEngine.test.ts src/orchestration/Layers/CheckpointReactor.test.ts src/orchestration/Layers/ProviderRuntimeIngestion.test.ts src/orchestration/Layers/ProviderCommandReactor.test.ts
• bun fmt
• bun lint
• bun typecheck (currently fails in apps/web due pre-existing @effect/atom-react / Layer.suspend errors)

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Note

Medium Risk
Changes the thread.message-sent projection write path to depend on a new getByMessageId query instead of scanning all messages in a thread, which could subtly affect message text/attachment merge behavior if the lookup or Option handling is incorrect.

Overview
Improves message projection performance by avoiding per-event thread-wide reads when handling thread.message-sent.

Adds a keyed ProjectionThreadMessageRepository.getByMessageId API (service + SQLite implementation) and refactors the projector to fetch only the prior row for that message to compute streaming text updates and attachment retention/clearing. Tests are extended to cover the new lookup path alongside existing attachment-preservation behavior.

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Note

Replace thread-wide message scan with direct lookup by messageId in projection pipeline

• Adds getByMessageId to ProjectionThreadMessageRepository (ProjectionThreadMessages.ts), returning Option<ProjectionThreadMessage> via a targeted SQL query instead of listing all thread messages.
• Updates the thread.message-sent handler in ProjectionPipeline.ts to use this new lookup, eliminating a full thread scan per message event.
• Introduces a shared toProjectionThreadMessage helper to consolidate row-to-domain mapping used by both listByThreadId and getByMessageId.

^{Macroscope summarized d64edba.}

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/backend-perf-message-projection

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[macroscopeapp]

Approvability

Verdict: Approved

Performance optimization that replaces a thread-wide message scan with a direct message ID lookup. The business logic is preserved and restructured using Effect's Option utilities. The PR author owns this code and tests are included.

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Dismissing prior approval to re-evaluate f23d141

Dismissing prior approval to re-evaluate d64edba