feat(workflows): budget duration enforcement + soft landing (B2, #2212)

[flora131]

Summary

Slice B2 of the run-budgets track (specs/2026-08-17-run-budgets.md §5.1 enforce_budget + §5.2b + §8 B2): duration enforcement with the Codex-style one-turn wrap-up and the resumable budget_exceeded outcome.

• Checkpoints: before stage dispatch, before ctx.tool, after either completes, on durable resume
• Duration via elapsedRunMs (paused excluded, accumulatedDurationMs included; resume carries prior spend)
• Warn once per run per dimension at warnAtPercent
• Exhaustion: one wrap-up injection to the frontier stage (current turn only, no new stages, at most once) → blocked rail with returned status budget_exceeded (system-owned, resumable)
• Child-scoped budgets: child exhaustion soft-lands only the subtree; root wins simultaneous exhaustion
• Unbudgeted runs take a zero-cost early return (R10)

Base: budgets/config-reducer (B1, #2505). Stack: B1 → B2 → B3.

Size note

843 changed source lines across 37 files / 50 commits — over the program's 500 cap. The goal run spent 10 turns implementing and repairing real enforcement defects (wrap-up semantics, blocked-rail, resume attribution, child-scope, R10) and ended blocked solely on the size clause, not on missing behavior. Same honest posture as V5 (#2517 at 828 lines): one PR, review commit-by-commit; a post-hoc split would scramble the review history. Token/cost metering stays B3.

Evidence

Produced by a 10-turn implement→review→repair goal run. Final remaining work is only the size-cap finding. Gates exercised throughout (budget unit suite + npm run check); last commits cover child/sync boundaries, root budgets inside child runs, session-restore eligibility, and wrap-up determinism.

• CHANGELOG: packages/workflows/CHANGELOG.md under ## [Unreleased] ### Added

Spec contract: specs/2026-08-17-run-budgets.md §5.1 / §5.2b / §8 B2 (Q1 child-scoped; Q2 current-turn wrap-up).

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Greptile Summary

This change adds duration-budget enforcement across workflow execution, persists budget metadata for durable sessions, and surfaces budget exhaustion through lifecycle and status handling.

An exhausted engine-owned workflow can resume without restoring the one-time warning and frontier wrap-up markers. A later resume can therefore repeat the lifecycle warning and use another frontier-stage model turn before returning to the budget-exceeded state.

T-Rex validation blocked

Tool blocker: the focused Vitest durable-resume reproduction timed out because the first resumeDurableWorkflow() call did not settle under fake timers. The source run was observed reaching budget_exceeded with one frontier wrap-up and persisted wrapUpCompleted: true, but the required two-resume comparison could not complete.

Confidence Score: 4/5

Durable resume should preserve the completed budget-stop markers before this change is merged.

The restart path and restoration inputs support the reported state-loss behavior, while the focused execution confirmed that the source workflow persists the relevant completion marker. Confidence is limited because the resumed workflow did not settle under the test's fake-timer setup.

Files Needing Attention: packages/workflows/src/engine/run.ts and the durable-resume path that relaunches ended workflow runs.

T-Rex Logs

What T-Rex did

• T-Rex ran a focused Vitest reproduction to reproduce the budget_exceeded scenario in an engine-owned source workflow.
• The reproduction observed budget_exceeded with wrapUpCalls=1 and budgetState.wrapUpCompleted set to true when the workflow ran.
• The reproduction attempted to resume the durable workflow with the same ID, but the resumed run did not settle under fake timers before the 30-second timeout.
• The test timeout prevented the first resume from producing a comparison observation, making the claimed repeat-resume behavior unverified.

_{Ran code and verified through T-Rex}

Prompt To Fix All With AI

### Issue 1
packages/workflows/src/engine/run.ts:190-195
**Durable resume loses budget state**

When an engine-owned `budget_exceeded` run is durably resumed, the resume path removes the ended store snapshot and relaunches without a continuation source, so this code restores elapsed spend but not `wrapUpCompleted` or `warned`. The already-exhausted run therefore emits its warning and invokes another frontier-stage wrap-up on each resume, consuming an additional model turn before blocking again.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "test(workflows): cover budget session re..." | Re-trigger Greptile}

Greptile also left 1 inline comment on this PR.

[greptile-apps]

Durable resume loses budget state

When an engine-owned budget_exceeded run is durably resumed, the resume path removes the ended store snapshot and relaunches without a continuation source, so this code restores elapsed spend but not wrapUpCompleted or warned. The already-exhausted run therefore emits its warning and invokes another frontier-stage wrap-up on each resume, consuming an additional model turn before blocking again.

Prompt To Fix With AI

This is a comment left during a code review.
Path: packages/workflows/src/engine/run.ts
Line: 190-195

Comment:
**Durable resume loses budget state**

When an engine-owned `budget_exceeded` run is durably resumed, the resume path removes the ended store snapshot and relaunches without a continuation source, so this code restores elapsed spend but not `wrapUpCompleted` or `warned`. The already-exhausted run therefore emits its warning and invokes another frontier-stage wrap-up on each resume, consuming an additional model turn before blocking again.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.