fix(engine): project CE steps after review handoff (#2464)

## Summary

- reconcile successful graph-native workflow results with pending task
checklist steps even when review handoff already moved the card into the
merge column
- preserve terminal, paused, and no-redundant-move behavior
- cover the real Compound Engineering post-review-handoff state with a
regression test

## Root cause

Compound Engineering runs `review-handoff` before `merge`. Review
handoff moves the task to `in-review`, which is also the merge column.
`ensureWorkflowMergeBoundaryTask()` returned immediately for cards
already in that column, before projecting successful
`workflowStepResults` onto legacy `Task.steps[]`. The merger then saw
`0/N` and rejected approved work with `task has incomplete steps`.

## Verification

- RED: regression test failed before the fix because `store.updateTask`
was never called
- GREEN: `executor-graph-boundary.test.ts` — 6 passed
- relevant non-PostgreSQL set — 31 passed, 5 PostgreSQL tests explicitly
skipped
- `@fusion/engine` typecheck passed
- changeset format passed
- `git diff --check` passed

## Baseline note

`ce-workflow-step-executor.test.ts` currently has three failures on
clean `origin/main` after FN-8601 foreach-proof hardening. The same
failures reproduce without this patch and are not regressions from this
change.


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Bug Fixes**
* Improved reconciliation after review handoff by projecting completed
step results onto the legacy checklist when reaching the merge column.
* Prevented tasks from being marked approved with incomplete step counts
(including “0/N” style states).
* Reduced unnecessary merge failures and deadlock/pause scenarios when
merge-column progress was already recorded.
* **Tests**
* Added coverage for execute-and-merge workflows, ensuring
merge-boundary resolution updates pending steps without moving the task.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

.changeset/ce-review-handoff-step-projection.md

@@ -0,0 +1,7 @@
+---
+"@runfusion/fusion": patch
+---
+
+summary: Graph-native workflows now reconcile completed task steps after review handoff reaches the merge column.
+category: fix
+dev: `ensureWorkflowMergeBoundaryTask` evaluates successful node-result proof and projects it onto the legacy checklist before applying its already-at-merge-column no-op. This prevents Compound Engineering tasks from reaching approved review at `0/N`, failing merge with `task has incomplete steps`, and deadlock-pausing.

packages/engine/src/__tests__/executor-graph-boundary.test.ts

@@ -36,7 +36,36 @@ function benchmarkIr(): WorkflowIr {
   } as WorkflowIr;
 }
 
-function makeExecutor(opts: { selection?: { workflowId: string; stepIds: string[] }; ir?: WorkflowIr; taskColumn?: string }) {
+function executeIr(): WorkflowIr {
+  return {
+    version: "v2",
+    name: "execute then merge",
+    columns: [
+      { id: "in-progress", name: "In progress", traits: [] },
+      { id: "in-review", name: "In review", traits: [{ trait: "merge" }, { trait: "merge-blocker" }] },
+    ],
+    nodes: [
+      { id: "execute", kind: "prompt", column: "in-progress", config: { seam: "execute" } },
+      { id: "merge", kind: "merge-gate", column: "in-review" },
+    ],
+    edges: [{ from: "execute", to: "merge", condition: "success" }],
+  } as WorkflowIr;
+}
+
+function makeExecutor(opts: {
+  selection?: { workflowId: string; stepIds: string[] };
+  ir?: WorkflowIr;
+  taskColumn?: string;
+  steps?: Array<{ id: string; title: string; status: "pending" | "done" }>;
+  workflowStepResults?: Array<{
+    workflowStepId: string;
+    workflowStepName: string;
+    source: "node";
+    phase: "pre-merge";
+    status: "passed";
+    completedAt: string;
+  }>;
+}) {
   const store = createMockStore() as unknown as Record<string, unknown>;
   const liveTask = {
     id: "FN-B1",
@@ -44,7 +73,8 @@ function makeExecutor(opts: { selection?: { workflowId: string; stepIds: string[
     description: "",
     column: opts.taskColumn ?? "in-review",
     dependencies: [],
-    steps: [],
+    steps: opts.steps ?? [],
+    workflowStepResults: opts.workflowStepResults ?? [],
     currentStep: 0,
     log: [],
     prompt: "# t",
@@ -109,4 +139,44 @@ describe("U5a — IR-driven merge boundary (scenario 1)", () => {
     const moveTask = store.moveTask as ReturnType<typeof vi.fn>;
     expect(moveTask).not.toHaveBeenCalled();
   });
+
+  /*
+  FNXC:WorkflowLifecycle 2026-07-26-22:59:
+  Successful pre-merge proof must still project graph-native results onto legacy steps after review handoff has already moved the card into the merge column; the projection must not trigger a redundant move.
+  */
+  it("projects graph-native completion after review handoff already moved the card to the merge column", async () => {
+    const pendingSteps = [
+      { id: "0", title: "Preflight", status: "pending" as const },
+      { id: "1", title: "Implement", status: "pending" as const },
+    ];
+    const { executor, store, liveTask } = makeExecutor({
+      selection: { workflowId: "custom:execute", stepIds: [] },
+      ir: executeIr(),
+      taskColumn: "in-review",
+      steps: pendingSteps,
+      workflowStepResults: [{
+        workflowStepId: "execute",
+        workflowStepName: "Execute",
+        source: "node",
+        phase: "pre-merge",
+        status: "passed",
+        completedAt: new Date().toISOString(),
+      }],
+    });
+
+    await executor.ensureWorkflowMergeBoundaryTask(
+      liveTask,
+      { reason: "workflow-merge-boundary", nodeId: "merge", workflowId: "custom:execute", runId: "r1" },
+    );
+
+    expect(store.updateTask).toHaveBeenCalledWith(
+      "FN-B1",
+      {
+        steps: pendingSteps.map((step) => ({ ...step, status: "done" })),
+        currentStep: 1,
+      },
+      undefined,
+    );
+    expect(store.moveTask).not.toHaveBeenCalled();
+  });
 });

packages/engine/src/executor.ts

@@ -7623,10 +7623,12 @@ export class TaskExecutor {
     */
     const targetColumn = await this.resolveMergeBoundaryColumn(task.id, metadata.nodeId);
 
-    // Already at the merge column, or in the terminal (done/complete) column:
-    // nothing to do. builtin:coding's targetColumn is `in-review`, so this stays
-    // byte-identical to the pre-cutover `in-review || done` guard.
-    if (live.column === targetColumn || live.column === "done") return live;
+    /*
+    FNXC:WorkflowMerge 2026-07-26-22:59:
+    A prior review handoff can move a graph-native workflow into its merge column before this boundary projects successful node results onto the legacy checklist. Preserve the no-move behavior, but do not return until the projection has run.
+    */
+    const alreadyAtMergeColumn = live.column === targetColumn;
+    if (live.column === "done") return live;
     if (live.paused || live.userPaused) return live;
 
     /*
@@ -7669,6 +7671,7 @@ export class TaskExecutor {
         this.getRunContextFor(live.id),
       );
     }
+    if (alreadyAtMergeColumn) return live;
     const moveOptions = {
       preserveProgress: true,
       moveSource: "engine" as const,