fix: checkpoint diffs never resolve due to shared PubSub subscriptions

[jasonLaster]

Stream.fromPubSub() creates a subscription eagerly. Storing the result as a property meant all consumers shared one queue, so only the first reader (wsServer/ProviderRuntimeIngestion) got events. CheckpointReactor received zero events and never captured git checkpoints.

Fix: change streamDomainEvents and streamEvents to getters so each consumer gets its own subscription. Also add a domain event handler that replaces placeholder checkpoints with real git captures, and extract shared CWD resolution and capture logic to reduce duplication.

Closes #585
Closes #595

Note

Fix checkpoint diffs never resolving due to shared PubSub subscriptions

• Converts streamDomainEvents in OrchestrationEngine and streamEvents in ProviderService from fixed stream exports to getters that call Stream.fromPubSub() on each access, giving each consumer an independent subscription.
• Adds a captureCheckpointFromPlaceholder handler in CheckpointReactor that replaces placeholder (status "missing") checkpoints with a real git checkpoint when a thread.turn-diff-completed event is received.
• Refactors captureCheckpointFromTurnCompletion so placeholder checkpoints no longer block a real capture for the same turn, and centralizes cwd resolution and capture dispatch into resolveCheckpointCwd and captureAndDispatchCheckpoint helpers.
• Behavioral Change: workspace index cache is no longer cleared after checkpoint capture, and missing cwd/non-git workspaces now silently skip rather than emitting warning logs.

^{Macroscope summarized 661a179.}

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[macroscopeapp]

🔴 Critical Layers/CheckpointReactor.ts:424

captureCheckpointFromPlaceholder references targetCheckpointRef, fromCheckpointRef, and nextTurnCount which are never declared in its scope, so it throws ReferenceError at runtime. The function also calls captureAndDispatchCheckpoint with missing arguments (no turnCount, status, etc.) and then duplicates that function's logic manually, which would emit duplicate events. This appears to be an incomplete refactor where code was copied from captureCheckpointFromTurnCompletion without the corresponding variable definitions.

🚀 Reply "fix it for me" or copy this AI Prompt for your agent:

In file apps/server/src/orchestration/Layers/CheckpointReactor.ts around line 424:

`captureCheckpointFromPlaceholder` references `targetCheckpointRef`, `fromCheckpointRef`, and `nextTurnCount` which are never declared in its scope, so it throws `ReferenceError` at runtime. The function also calls `captureAndDispatchCheckpoint` with missing arguments (no `turnCount`, `status`, etc.) and then duplicates that function's logic manually, which would emit duplicate events. This appears to be an incomplete refactor where code was copied from `captureCheckpointFromTurnCompletion` without the corresponding variable definitions.

Evidence trail:
apps/server/src/orchestration/Layers/CheckpointReactor.ts lines 387-520 (REVIEWED_COMMIT) - `captureCheckpointFromPlaceholder` function definition and body showing undeclared variables `targetCheckpointRef`, `fromCheckpointRef`, `nextTurnCount`
apps/server/src/orchestration/Layers/CheckpointReactor.ts lines 190-220 (REVIEWED_COMMIT) - `captureAndDispatchCheckpoint` function signature showing required parameters including `turnCount`, `status`, `assistantMessageId`, `createdAt`
apps/server/src/orchestration/Layers/CheckpointReactor.ts lines 314-378 (REVIEWED_COMMIT) - `captureCheckpointFromTurnCompletion` function showing correct pattern with proper variable declarations