refactor(server): share scheduling for tasks and limit recovery

[juliusmarminge]

Limit retries added a separate 30-second polling loop alongside Scheduled Tasks. Extract the existing five-second task scheduler into one shared server primitive and register both features with it.

The scheduler checks due work on registration, then every five seconds. It owns source lifetimes, error isolation, and preventing overlapping sweeps. Slow task work does not delay limit recovery. Each feature keeps its existing persisted state and dispatch guards, so retries survive restarts without becoming user-visible Scheduled Tasks. Limit recovery uses one focused SQLite query for unarmed failures affected by preferences and due enabled retries. Future, cancelled, archived, settled, and pending-request threads are excluded before decoding. Scheduler ticks no longer rebuild shell snapshots, count transcript history, or traverse fork ancestors.

Stacked on #12783.

Verification: 81 focused tests pass, covering the shared scheduler, overdue work after restart, SQL recovery filtering, cancellation, snooze deadlines, provider-session errors, latest root failures, and 15 dispatch guards. Scoped server typecheck and targeted lint pass. SQLite query-plan inspection confirms indexed latest-run/root-error lookups. The query still checks thread metadata every five seconds; CPU usage on large databases has not been benchmarked. No client presentation changes; automated behavior tests provide the evidence.

Model: GPT-6. Harness: Codex.

Summary by CodeRabbit

• New Features

  • Added centralized scheduling for recurring background work, including scheduled tasks and usage-limit recovery.
  • Coordinated due work across restarts while preventing overlapping executions.
  • Usage-limit recovery now identifies eligible failed threads and respects recovery timing, auto-resume, and snooze settings.

• Bug Fixes

  • Improved resilience so failures in one scheduled process do not stop other scheduled work.
  • Prevented overlapping background executions during slow processing.

• Tests

  • Added coverage for scheduling reliability, restart recovery, timing, cleanup, and recovery eligibility.

Integration verification: the shared scheduler constructor is private, fixing the unused export reported by CI. All five scheduler lifecycle and integration tests pass, including immediate overdue recovery, source isolation, interruption, and no overlapping work. Scoped server typecheck passes.

Built with GPT-6 in Codex.

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ No successful main baseline artifact is available yet. This run establishes the initial measurement.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	—	4.9 KiB	—	6.8 KiB	✅
Codex	Thread snapshot wire	—	3.7 KiB	—	4.9 KiB	✅
Codex	Live turn WebSocket wire	—	1.2 KiB	—	2.0 KiB	✅
Codex	Live turn WebSocket decoded	—	20.4 KiB	—	29.3 KiB	✅
Codex	Live turn messages	—	2	—	8	✅
Claude	Total thread wire	—	4.9 KiB	—	6.8 KiB	✅
Claude	Thread snapshot wire	—	3.7 KiB	—	4.9 KiB	✅
Claude	Live turn WebSocket wire	—	1.2 KiB	—	2.0 KiB	✅
Claude	Live turn WebSocket decoded	—	20.8 KiB	—	29.3 KiB	✅
Claude	Live turn messages	—	2	—	8	✅

Baseline: unavailable · PR result: 4dc66ff · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 106.1 KiB
• Claude decoded thread snapshot: 106.4 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

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Review profile: CHILL

Plan: Team

Run ID: 304e4e8c-28b1-48d2-9335-1aeabaccb419

📥 Commits

Reviewing files that changed from the base of the PR and between f5cc6ed and f34dc5e3d9b85e2c21355441a1132ceb450dcd30.

📒 Files selected for processing (2)

• apps/server/src/orchestration-v2/ProjectionStore.test.ts
• apps/server/src/orchestration-v2/ProjectionStore.ts

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📝 Walkthrough

Walkthrough

The PR adds a shared Effect scheduler with scoped registrations, serialized execution, failure handling, and five-second polling. Scheduled-task and usage-limit recovery services use it. The projection store supplies filtered recovery candidates. Tests cover concurrency, cleanup, restart, and recovery behavior.

Changes

Shared scheduler adoption

Layer / File(s)	Summary
Scheduler implementation and behavior apps/server/src/scheduling/Scheduler.ts, apps/server/src/scheduling/Scheduler.test.ts	Adds scoped registration, five-second polling, per-source serialization, failure handling, scope cleanup, and scheduler behavior tests.
Limit-recovery candidate projection apps/server/src/orchestration-v2/ProjectionStore.ts, apps/server/src/orchestration-v2/ProjectionStore.test.ts, apps/server/src/orchestration-v2/ProviderTurnControlService.test.ts	Adds the candidate type and store method. SQL and in-memory implementations filter candidates by thread state, reset timing, recovery state, and configuration.
Service registration and production wiring apps/server/src/scheduledTasks/*, apps/server/src/orchestration-v2/UsageLimitRecoveryService.ts, apps/server/src/orchestration-v2/runtimeLayer.ts, apps/server/src/orchestration-v2/ThreadLaunchService.test.ts	Moves scheduled-task and usage-limit recovery polling to the shared scheduler. Production and test layers provide Scheduler.layer.
Cross-service integration validation apps/server/src/scheduling/Scheduler.integration.test.ts	Tests scheduled-task execution and persisted usage-limit recovery at reset time and after restart.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Refactor

Suggested reviewers: saphid

Sequence Diagram(s)

sequenceDiagram
  participant Scheduler
  participant ScheduledTaskService
  participant UsageLimitRecoveryService
  participant ProjectionStore
  participant OrchestrationService
  Scheduler->>ScheduledTaskService: Run registered due-task work
  ScheduledTaskService->>OrchestrationService: Dispatch due task
  Scheduler->>UsageLimitRecoveryService: Run registered recovery work
  UsageLimitRecoveryService->>ProjectionStore: Get limit-recovery candidates
  UsageLimitRecoveryService->>OrchestrationService: Dispatch recovery retry

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🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 12 files.
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.
Title check	✅ Passed	The title clearly summarizes the primary change: sharing one server scheduler between scheduled tasks and limit recovery.
Description check	✅ Passed	The description explains what changed, why the shared scheduler is needed, implementation details, verification results, and UI impact. The checklist section from the template is not included, but the…

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[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR introduces a new production scheduler and changes the timing, lifecycle, concurrency, and persistence-query behavior of both scheduled tasks and usage-limit recovery. Because it restructures shared background infrastructure and alters existing runtime workflows, human review is warranted.

No code changes detected at 4dc66ff. Prior analysis still applies.

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[macroscopeapp]

Effect Service Conventions found one blocking issue; see the inline review comment for the required namespace-import fix.

^{Posted via Macroscope — Effect Service Conventions}

[macroscopeapp]

Effect Service Conventions found one blocking issue; see the inline review comment for the required exported service constructor fix.

^{Posted via Macroscope — Effect Service Conventions}