From f22ebca62ace0b970671d94c3b8f97e6335dfe3b Mon Sep 17 00:00:00 2001
From: Fusion Agent <noreply@runfusion.ai>
Date: Tue, 25 Aug 2026 05:38:46 +0000
Subject: [PATCH] test(FN-WF): treat a revoked merge gate as the deferral it
 is, and stop the engine before clearing globals
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Two harness correctness fixes, both found chasing the S05 flake.

REVOKED GATE. `MergeGateRevokedError` escaped the graph dispatch and failed the
scenario. It is a DEFERRAL, not a failure — FN-180's own contract, and the reason
it carries a dedicated error type so callers cannot convert a gate lost mid-merge
into a retry or a failed park. It fires when a merge admitted on an earlier turn
reaches its ref-advance fence after a REVISE has already returned the card to
in-progress: the engine refusing correctly while the driver races it. The dispatch
now swallows ONLY that type, by NAME rather than by import, because importing
merger-errors.js would break the pre-FN-180 differential run the harness self-test
enforces.

TEARDOWN ORDER. `dispose` reset the shared mock registry and cleared
`activeSessionRegistry` BEFORE stopping the engine, stranding in-flight sessions on
default scripts mid-teardown and hiding them from the liveness checks the stop path
consults. Both are process-global, so the damage landed on whichever file ran next.

Together these took S05 on builtin:coding-ideas-v2 from failing 3 runs out of 3 to
2 out of 6 — a real reduction, and not zero, so it is still not shipped. S05 stays
on its original workflows, where the lane is green four consecutive full runs:
122.4s, 126.6s, 124.0s, 116.9s of the 150s budget.

builtin:coding-ideas-v2 remains at 18 of 19 scenarios plus the multi-repository
workspace drive.
---
 .../pipeline-smoke/_pipeline-harness.ts       | 25 +++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/packages/engine/src/__tests__/pipeline-smoke/_pipeline-harness.ts b/packages/engine/src/__tests__/pipeline-smoke/_pipeline-harness.ts
index 9b98e9134a..81e34051ae 100644
--- a/packages/engine/src/__tests__/pipeline-smoke/_pipeline-harness.ts
+++ b/packages/engine/src/__tests__/pipeline-smoke/_pipeline-harness.ts
@@ -354,11 +354,18 @@ export class PipelineSmokeHarness {
 
   async dispose(): Promise<void> {
     try {
+      /*
+      FNXC:PipelineSmoke 2026-08-24-23:10:
+      Stop the engine BEFORE clearing the shared registries. Resetting the mock registry while
+      sessions are still in flight strands them on default scripts mid-teardown, and clearing
+      `activeSessionRegistry` first hides those sessions from the liveness checks the stop path
+      consults. Both are process-global, so the damage lands on whichever file runs next.
+      */
+      await this.engine.stop();
       activeSessionRegistry.clear();
       this.mockScriptStates.clear();
       this.scriptedBranches.clear();
       resetMockScripts();
-      await this.engine.stop();
       this.guard.restore();
       await this.centralCore.close();
       // The shared PG harness owns taskStore.asyncLayer and closes it after this file.
@@ -1218,7 +1225,21 @@ export class PipelineSmokeHarness {
       throw new Error("Pipeline smoke did not resolve the executor's authoritative workflow seams.");
     }
     this.authoritativeSeamsObserved = true;
-    await executor.executeAuthoritativeGraph(task);
+    /*
+    FNXC:PipelineSmoke 2026-08-24-23:10:
+    A revoked merge gate is a DEFERRAL, not a failure. That is FN-180's own contract and the reason
+    it carries a dedicated error type, so callers cannot convert a gate lost mid-merge into a retry
+    or a failed park. It surfaces here when a merge admitted on an earlier turn reaches its
+    ref-advance fence after a REVISE has already returned the card to in-progress: the engine is
+    refusing correctly, and the driver must simply take another turn. Swallowing ONLY this type
+    keeps every other merge failure fatal to the scenario.
+    */
+    try {
+      await executor.executeAuthoritativeGraph(task);
+    } catch (error) {
+      /* Detected by NAME: importing merger-errors.js would break the pre-FN-180 differential run. */
+      if ((error as { name?: string } | undefined)?.name !== "MergeGateRevokedError") throw error;
+    }
     const after = await this.freshTask(taskId);
     if (after.mergeDetails?.mergeConfirmed === true) this.manualHoldTaskIds.delete(taskId);
     return after;