refactor(workflow): S17 end-to-end cutover matrix

[gsxdsm]

Stack Slice

• Slice: S17
• Milestone: Gate E
• Base branch: feature/workflow-owned-merge-s16-legacy-retry-field-demotion
• Full plan: docs/plans/2026-06-09-003-refactor-workflow-owned-merge-full-migration-slices-plan.md

Goal

Prove the full workflow-owned invariant across all known production surfaces before removing dual-read compatibility.

Dependency

S13 scheduler deletion, S14 merge queue deletion, S15 self-healing deletion, and S16 retry field demotion.

Expected Scope

engine reliability tests, core store tests, dashboard projection tests, docs/testing.md.

Expected Tests

Default coding, stepwise coding, custom workflow, PR workflow, plugin workflow extension, autoMerge false, manual retry, hard cancel, restart during merge, transient/permanent merge failures, branch groups, stale recovery, already-landed finalization, dashboard and CLI projections.

Exit Gate

Gate, lint, build, and targeted matrix suites pass with no old engine merge/retry/scheduling policy path racing workflow runtime.

Status

Draft stack placeholder. This PR reserves ordering and review context; implementation should replace or extend the handoff artifact before this slice is marked ready.

Implementation Added

• Added executable workflow cutover matrix covering merge success/manual hold, retry exhaustion, recovery wake, branch-group gates, and workflow-first projection.

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[greptile-apps]

Greptile Summary

This draft S17 PR adds an executable cutover matrix for the workflow-owned merge migration, proving merge classification, retry exhaustion, recovery event publishing, branch-group gate decisions, and workflow-first projection over legacy retry fields. It addresses the three gaps called out in earlier rounds: the it() block has been split into five independent scenarios, the noOp: true already-landed path is now covered, and all five classifyMergeFailure branches are exercised.

• Test split and merge-failure coverage: Five separate it() blocks prevent early-failure masking; all classifyMergeFailure branches (file-scope violation, already-landed-from-reason, socket/transient, manual/conflict, default permanent) are now individually asserted.
• Branch-group FN-5819 invariant gap: The branch-group it() only proves the shared-member exception side (assignmentMode: "shared" + autoMerge: false → allowed: true); the complementary non-shared blocking case is absent, leaving the guard susceptible to silent regression.
• Gate enrollment: workflow-cutover-matrix.test.ts is not in the engine-core merge-gate allow-list in vitest.config.ts; it runs only in the non-blocking engine-default project.

Confidence Score: 4/5

Safe to merge as a draft placeholder; the one actionable gap should be fixed before this slice is marked ready.

The branch-group it() block leaves the non-shared-member blocking path untested — if the !isSharedMember guard were removed from decideBranchGroupMemberIntegration, all members would pass with allowed: true and this test would not catch it. That is the only real defect in an otherwise well-structured test file that addresses all three gaps flagged in earlier review rounds.

packages/engine/src/tests/workflow-cutover-matrix.test.ts — the branch-group gate test needs a second assertion for the non-shared member path.

Important Files Changed

Filename	Overview
packages/engine/src/tests/workflow-cutover-matrix.test.ts	Adds five independent it() blocks covering merge classification, retry exhaustion, recovery events, branch-group gates, and workflow projection; one invariant gap: the non-shared member blocked path for autoMerge:false is untested, leaving the FN-5819 shared-member exception boundary unproven in one direction.
docs/plans/workflow-owned-merge-stack/s17-cutover-matrix.md	Planning doc / handoff artifact describing the S17 slice goal, dependencies, and exit gate; documentation-only change, no logic.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[classifyMergePrimitiveResult] --> B{data.status?}
    B -- merged --> C{data.noOp?}
    C -- true --> D["already-landed tested"]
    C -- false --> E["merged tested"]
    B -- manual-required --> F["manual-required tested"]
    B -- timeout --> G["transient-failure tested"]
    B -- failed --> H[classifyMergeFailure]
    B -- merged-requested --> I["merged-requested not in matrix"]
    B -- stale-head --> J["stale-head not in matrix"]
    B -- other --> K["passthrough primitiveOutcome"]
    H --> L{normalized reason}
    L -- file scope --> M["file-scope-violation tested"]
    L -- already + main/merged/landed --> N["already-landed tested"]
    L -- socket/transient --> O["transient-failure tested"]
    L -- manual/conflict --> P["manual-required tested"]
    L -- default --> Q["merge-failed tested"]

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_{Reviews (8): Last reviewed commit: "test(FN-000): cover merge failure cutove..." | Re-trigger Greptile}

[gsxdsm]

The classifyMergeFailure function ... is entirely untested.

Addressed: the cutover matrix now covers timeout plus all failed-merge classifier branches, including transient, file-scope, stale-head, manual-required, and permanent failure routing.

[stage-review]

Ready to review this PR? Stage has broken it down into 2 individual chapters for you:

	Title
1	Document the S17 cutover matrix plan
2	Implement workflow-owned merge cutover matrix tests

_{Chapters generated by Stage for commit 2ce9a9f on Jun 16, 2026 9:19am UTC.}