fix(engine): defer validator fail to inconclusive while the linked task is unmerged

[flexi767]

Problem

MissionExecutionLoop.runFeatureValidation treats a validator "fail" verdict as authoritative regardless of whether the linked task's code has actually landed. When validation fires while the task is still mid-pipeline — an in-review PR, an external merge train, a deferred base sync — the validator judges a checkout that predates the merge, concludes the feature "is not present", and handleValidationFail mints a Fix feature for work that is already done.

We hit this in production (2026-07-05): a recovery-path validation ran against four features whose implementing tasks were in-review in an external merge pipeline. All four "failed" → four duplicate Fix tasks were created one minute after the real work merged. Worse, the Fix tasks' planned file scopes included hot shared files, so their file-scope leases serialized the entire board until they were manually archived.

Fix

Before dispatching a fail verdict, resolve the linked task's column. If it affirmatively shows the task has not completed (any column other than done/archived), route the outcome to handleValidationInconclusive (R21 — completes the run as blocked, logs verification_inconclusive, notifies autopilot, spawns no Fix feature) with a "code not merged yet — validation deferred" reason. A later validation (post-merge recovery pass) judges the real merged code.

Fails open by design — the guard may only ever defer a fail, never suppress one on missing data. Missing taskId, missing task, unreadable store, or unknown column all fall through to the normal handleValidationFail path:

private async getPremergeTaskColumn(taskId: string | undefined): Promise<string | null> {
  if (!taskId) return null;
  const linkedTask = await this.taskStore.getTask(taskId).catch(() => null);
  const column = linkedTask?.column;
  if (!column || column === "done" || column === "archived") return null;
  return column;
}

The vanilla flow is unaffected: the scheduler triggers validation on toColumn === "done", so by the time a normally-triggered validation runs the task is already done and the guard is a no-op. Only recovery-path / re-validation runs that race an unmerged task are deferred.

Tests

Three new tests in mission-execution-loop.test.ts (premerge guard describe):

1. fail verdict + linked task in-review → routes to inconclusive: no Fix feature, run completed as blocked, validation:inconclusive emitted (not validation:failed), verification_inconclusive mission event logged
2. fail verdict + linked task done → normal fail path: Fix feature created, validation:failed emitted
3. fail verdict + taskStore.getTask rejects → fails open to the normal fail path

npx vitest run src/__tests__/mission-execution-loop.test.ts: 58/58 green. npx tsc --noEmit: clean. Full engine suite: the 46 failures across 24 files present on my branch fail identically on clean 17c4007 (verified by re-running the same files on a detached checkout of upstream main) — all pre-existing/environment-dependent, none related to this change.

Summary by CodeRabbit

• Bug Fixes
  • Validation failures now account for whether the linked task is actually merged. If the task is still in progress, the result is marked as inconclusive instead of creating a fix flow.
  • Added clearer handling when task details can’t be read, so normal failure behavior still applies.
  • Improved validation status reporting and event logging for merged vs. unmerged task states.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[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: 4b4b8832-9479-46b5-b37f-f1c90f9593ec

📥 Commits

Reviewing files that changed from the base of the PR and between 17c4007 and c73c700.

📒 Files selected for processing (2)

• packages/engine/src/__tests__/mission-execution-loop.test.ts
• packages/engine/src/mission-execution-loop.ts

---

📝 Walkthrough

Walkthrough

This change modifies MissionExecutionLoop.runFeatureValidation to check the linked task's board column before handling a validator "fail" verdict. A new getPremergeTaskColumn helper determines whether the fail should be deferred as inconclusive or processed normally. Corresponding tests are added.

Changes

Premerge Guard for Validation Fail Verdict

Layer / File(s)	Summary
Premerge column check and fail routing packages/engine/src/mission-execution-loop.ts	Adds getPremergeTaskColumn(taskId) to resolve a linked task's column, returning it only when the task is not done/archived; the "fail" branch now routes to handleValidationInconclusive when the task is pre-merge, otherwise falls back to handleValidationFail, failing open when the task is missing or unreadable.
Premerge guard test suite packages/engine/src/__tests__/mission-execution-loop.test.ts	Adds tests priming a fail verdict with a linked task: verifies deferral to inconclusive (blocked status, validation:inconclusive emission, warning event) when task is not done, verifies normal fail flow (validation:failed) when task is done, and verifies fail-open behavior when the linked task cannot be read.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Possibly related PRs

• Runfusion/Fusion#1345: Both PRs modify runFeatureValidation in mission-execution-loop.ts, one centralizing the flow and this one adding column-based fail routing.
• Runfusion/Fusion#1666: Both PRs change how the validator's "fail" outcome is routed to other terminal/inconclusive states within the same file.

Poem

A task not merged, still in review,
the guard says "wait, don't jump the queue!"
Inconclusive whispers, warning logged,
but once it's done, the fail's not dodged.
Fail open wide when data's lost —
a rabbit's caution, worth the cost. 🐇

🚥 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 summarizes the main behavior change in the validator flow.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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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[greptile-apps]

Greptile Summary

This PR changes validator failure handling when linked task code may not be merged yet. The main changes are:

• Added a guard before handling validator fail results.
• Routes failures for non-completed linked tasks to the inconclusive path.
• Keeps normal failure handling for completed, missing, or unreadable linked tasks.
• Added tests for deferred, completed, and task-store failure cases.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.
• The only concrete concern found during this follow-up matches an existing review thread and is not a separate issue.

Important Files Changed

Filename	Overview
packages/engine/src/mission-execution-loop.ts	Adds the linked-task column check before converting validator failures into generated Fix features.
packages/engine/src/tests/mission-execution-loop.test.ts	Adds focused tests for the new pre-merge validation guard.

_{Reviews (2): Last reviewed commit: "Merge branch 'main' into fix/validator-p..." | Re-trigger Greptile}