fix(core): thread review lanes through merge readiness

[plarson]

Summary

• thread resolved review lanes through isTaskReadyForMerge
• preserve required pre-merge step filtering
• add coverage for a renamed review lane

Test plan

• pnpm --filter @fusion/core exec vitest run --silent=passed-only --reporter=dot src/__tests__/task-merge.test.ts
• pnpm --filter @fusion/core typecheck
• pnpm check:lane-wiring
• pnpm check:changesets
• pnpm exec eslint packages/core/src/merge/task-merge.ts packages/core/src/__tests__/task-merge.test.ts

Summary by CodeRabbit

• Bug Fixes
  • Custom review lanes are now honored during merge-readiness checks and auto-merge processing.
  • Renamed workflow lanes correctly determine whether tasks can merge.
  • Tasks resumed from a paused state are routed and evaluated using the appropriate review lane.
  • The default in-review lane remains supported when no custom review lanes are configured.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: bdaf29b4-5a08-42ea-aa24-2534fb355c1f

📥 Commits

Reviewing files that changed from the base of the PR and between 8368b29 and a82511f.

📒 Files selected for processing (1)

• packages/engine/src/__tests__/project-engine-merge-lane-resolved.test.ts

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📝 Walkthrough

Walkthrough

The change threads resolved workflow review lanes through core merge checks and ProjectEngine admission paths. Non-empty lane sets are authoritative. Empty sets preserve the legacy in-review fallback.

Changes

Merge lane wiring

Layer / File(s)	Summary
Core merge blocker contract packages/core/src/merge/task-merge.ts, packages/core/src/__tests__/task-merge.test.ts	getTaskMergeBlocker uses resolved review columns when the set is non-empty. Empty sets fall back to in-review. isTaskReadyForMerge forwards the resolved columns. Tests cover both paths.
ProjectEngine admission wiring packages/engine/src/project-engine.ts, packages/engine/src/__tests__/project-engine-merge-lane-resolved.test.ts, .changeset/task-ready-lane-wiring.md	ProjectEngine passes resolved review lanes through merge eligibility, handoff, sweep, auto-healing, and pause-interruption checks. Integration coverage validates a renamed signoff lane and re-enqueue behavior. A patch changeset records the fix.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to a8251

This localized lane-wiring change is merge-ready after normal checks and review; no actionable merge-blocking risk remains.

Sequence Diagram(s)

sequenceDiagram
  participant ProjectEngine
  participant getTaskMergeBlocker
  participant MergeQueue
  ProjectEngine->>getTaskMergeBlocker: pass resolved reviewColumns
  getTaskMergeBlocker->>MergeQueue: evaluate task merge eligibility
  MergeQueue-->>getTaskMergeBlocker: return blocker result
  getTaskMergeBlocker-->>ProjectEngine: return merge readiness
  ProjectEngine->>MergeQueue: re-enqueue eligible task

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🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: passing resolved review lanes through core merge-readiness checks.
Docstring Coverage	✅ Passed	Docstring check was indeterminate for this PR — some files could not be analyzed in time. Not blocking.
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.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[Copilot]

Pull request overview

This pull request threads resolved review lanes through merge-readiness checks and adds renamed-lane coverage.

Changes:

• Passes reviewColumns through isTaskReadyForMerge.
• Preserves required pre-merge filtering.
• Adds a patch changeset and unit test coverage.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Review summary
packages/core/src/merge/task-merge.ts	Moderate: The live merge paths still call getTaskMergeBlocker directly, so custom review-lane readiness is unchanged at runtime.
packages/core/src/__tests__/task-merge.test.ts	Adds coverage for a renamed review lane.
.changeset/task-ready-lane-wiring.md	Nit: Targets private @fusion/core instead of the published @runfusion/fusion package.

Suppressed comments (1)

packages/core/src/merge/task-merge.ts:664

• FNXC:MergeReadiness 2026-08-23-18:30: A resolved workflow can produce an empty review set (for example, the v1/traitless IR path), and getTaskMergeBlocker treats any present Set, including an empty one, as authoritative. Forwarding that value makes a clean task in in-review fail the identity check instead of using the documented legacy fallback; existing callers guard this by passing undefined or only non-empty sets. Please preserve that distinction here or make the resolved-empty case explicit before exposing this option.

  return getTaskMergeBlocker(task, {
    reviewColumns: options.reviewColumns,
    requiredPreMergeStepIds: options.requiredPreMergeStepIds,

---

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[greptile-apps]

Greptile Summary

This PR threads resolved review-lane identities through core merge readiness and ProjectEngine’s live merge-admission paths while preserving the legacy fallback when lane resolution is unavailable.

• Adds custom review-lane support to isTaskReadyForMerge.
• Forwards resolved lanes through periodic sweep, queue dequeue, handoff, and unpause admission checks.
• Adds regression coverage for renamed lanes and empty resolved sets.
• Corrects the release changeset to target the published @runfusion/fusion package.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
packages/core/src/merge/task-merge.ts	Extends merge readiness to honor caller-provided review lanes and deliberately preserves the legacy fallback for absent or empty lane sets.
packages/engine/src/project-engine.ts	Passes task-specific resolved review lanes through the periodic sweep, final dequeue, handoff, and unpause merge-admission paths.
packages/core/src/tests/task-merge.test.ts	Covers custom review-lane admission and the empty-set legacy fallback.
packages/engine/src/tests/project-engine-merge-lane-resolved.test.ts	Verifies resolved-lane forwarding across the affected live ProjectEngine merge surfaces.
.changeset/task-ready-lane-wiring.md	Correctly records a patch for the published package using the repository’s required labeled changeset format.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  A[Resolve task review lane] --> B[ProjectEngine admission surface]
  B --> C[Pass reviewColumns]
  C --> D[getTaskMergeBlocker]
  D --> E{Resolved lanes available?}
  E -->|Yes| F[Check task column membership]
  E -->|No| G[Fallback to in-review]
  F --> H[Merge-ready decision]
  G --> H

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_{Reviews (5): Last reviewed commit: "Merge branch 'main' into fix/task-ready-..." | Re-trigger Greptile}

[coderabbitai]

Actionable comments posted: 1

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Inline comments:
In `@packages/engine/src/__tests__/project-engine-merge-lane-resolved.test.ts`:
- Around line 201-224: Expand the merge-readiness regression coverage beyond the
unpause handler: add cases for sweep and dequeue canMergeTask callers, plus
immediate and post-grace handoff checks. Assert each path invokes
getTaskMergeBlocker with the resolved signoff lane, reusing the existing
renamed-lane fixture and test setup where applicable.

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Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 60f35404-7dc0-40b5-957d-aef4aff313cc

📥 Commits

Reviewing files that changed from the base of the PR and between 455bdbc and 8368b29.

📒 Files selected for processing (5)

• .changeset/task-ready-lane-wiring.md
• packages/core/src/__tests__/task-merge.test.ts
• packages/core/src/merge/task-merge.ts
• packages/engine/src/__tests__/project-engine-merge-lane-resolved.test.ts
• packages/engine/src/project-engine.ts

Included review availability: Your plan provides up to 4 included reviews per hour; 3 remain after this review.