FN-5646: preserve AI body when canonicalizing merge commits

Fusion-Task-Id: FN-5646

Fusion-Task-Lineage: db989a0f-a7d9-4060-9754-84d71f21a8c2

packages/engine/src/__tests__/reliability-interactions/post-finalize-verification-noop.real-git.test.ts

@@ -134,6 +134,13 @@ describe("post-finalize verification failure reliability interactions (real git)
         true,
         preAttemptHeadSha,
         "",
+        undefined,
+        undefined,
+        undefined,
+        null,
+        null,
+        null,
+        new Set<string>(),
       );
       expect(finalized.ok && finalized.reason === "branch-already-merged-on-main").toBe(true);
 

packages/engine/src/__tests__/reliability-interactions/verification-fix-already-on-main.real-git.test.ts

@@ -60,6 +60,13 @@ describe("verification-fix already-on-main reliability interactions (real git)",
         true,
         preAttemptHeadSha,
         "",
+        undefined,
+        undefined,
+        undefined,
+        null,
+        null,
+        null,
+        new Set<string>(),
       );
       expect(finalized.ok && finalized.reason === "branch-already-merged-on-main").toBe(true);
       if (finalized.ok && finalized.reason === "branch-already-merged-on-main") {