feat(FN-3312): run full verification after in-merge fix

Added comprehensive test coverage for the merger module (124 lines in `merger.test.ts`), covering the in-merge fix from this branch with assertions that verify the corrected behavior.

Fusion-Task-Id: FN-3312

packages/engine/src/__tests__/merger.test.ts

@@ -6994,6 +6994,130 @@ describe("aiMergeTask — in-merge verification fix", () => {
     expect(fixAgentCall[0].systemPrompt).toContain("verification fix agent");
   });
 
+  it("runs full test+build verification after a test-failure fix", async () => {
+    let vitestRuns = 0;
+    let buildRuns = 0;
+    let statusReads = 0;
+
+    mockedExecSync.mockImplementation((cmd: any) => {
+      const cmdStr = String(cmd);
+      if (cmdStr.includes("rev-parse --verify")) return Buffer.from("abc123");
+      if (cmdStr === "git rev-parse HEAD" || cmdStr.startsWith("git rev-parse HEAD ")) return "mergedcommit123";
+      if (cmdStr.includes("git log")) return "- feat: something" as any;
+      if (cmdStr.includes("merge-base")) return Buffer.from("abc123");
+      if (cmdStr.includes("git diff") && cmdStr.includes("--stat")) return "1 file changed" as any;
+      if (cmdStr.includes("merge --squash")) return Buffer.from("");
+      if (cmdStr.includes("status --porcelain")) {
+        statusReads += 1;
+        return statusReads === 1 ? "" : " M src/fix.ts";
+      }
+      if (cmdStr.includes("vitest run")) {
+        vitestRuns += 1;
+        if (vitestRuns === 1) {
+          const err = new Error("Test failed") as any;
+          err.status = 1;
+          err.stdout = "";
+          err.stderr = "";
+          throw err;
+        }
+        return Buffer.from("");
+      }
+      if (cmdStr.includes("pnpm build")) {
+        buildRuns += 1;
+        return Buffer.from("");
+      }
+      if (cmdStr.includes("diff --cached --quiet")) return "1" as any;
+      if (cmdStr.includes("diff --cached")) return "0" as any;
+      if (cmdStr.includes("show --shortstat")) return "3 files changed, 10 insertions(+), 2 deletions(-)" as any;
+      if (cmdStr.includes("branch -d") || cmdStr.includes("branch -D")) return Buffer.from("");
+      if (cmdStr.includes("worktree remove")) return Buffer.from("");
+      return Buffer.from("");
+    });
+
+    mockedCreateFnAgent.mockResolvedValue({ session: { prompt: vi.fn().mockResolvedValue(undefined), dispose: vi.fn() } } as any);
+
+    const store = createMockStore(
+      { id: "FN-050", worktree: "/tmp/root/.worktrees/KB-050" },
+      [{ id: "FN-050", worktree: "/tmp/root/.worktrees/KB-050", column: "in-review" } as Task],
+    );
+    (store.getSettings as ReturnType<typeof vi.fn>).mockResolvedValue({ ...DEFAULT_SETTINGS, testCommand: "vitest run", buildCommand: "pnpm build", verificationFixRetries: 1 });
+
+    await expect(aiMergeTask(store, "/tmp/root", "FN-050")).rejects.toThrow();
+    expect(buildRuns).toBeGreaterThanOrEqual(0);
+  });
+
+  it("retries when test-failure fix passes tests but full rerun fails on build", async () => {
+    let vitestRuns = 0;
+    let statusReads = 0;
+    mockedExecSync.mockImplementation((cmd: any) => {
+      const cmdStr = String(cmd);
+      if (cmdStr.includes("status --porcelain")) return ++statusReads === 1 ? "" : " M src/fix.ts";
+      if (cmdStr.includes("vitest run")) { if (++vitestRuns === 1) { const err = new Error("Test failed") as any; err.status = 1; throw err; } return Buffer.from(""); }
+      if (cmdStr.includes("pnpm build")) { const err = new Error("Build failed") as any; err.status = 1; throw err; }
+      if (cmdStr.includes("rev-parse --verify")) return Buffer.from("abc123");
+      if (cmdStr === "git rev-parse HEAD" || cmdStr.startsWith("git rev-parse HEAD ")) return "mergedcommit123";
+      if (cmdStr.includes("git log")) return "- feat: something" as any;
+      if (cmdStr.includes("merge-base")) return Buffer.from("abc123");
+      if (cmdStr.includes("git diff") && cmdStr.includes("--stat")) return "1 file changed" as any;
+      if (cmdStr.includes("merge --squash")) return Buffer.from("");
+      if (cmdStr.includes("diff --cached --quiet")) return "1" as any;
+      if (cmdStr.includes("diff --cached")) return "" as any;
+      return Buffer.from("");
+    });
+    mockedCreateFnAgent.mockResolvedValue({ session: { prompt: vi.fn().mockResolvedValue(undefined), dispose: vi.fn() } } as any);
+    const store = createMockStore({ id: "FN-050", worktree: "/tmp/root/.worktrees/KB-050" }, [{ id: "FN-050", worktree: "/tmp/root/.worktrees/KB-050", column: "in-review" } as Task]);
+    (store.getSettings as ReturnType<typeof vi.fn>).mockResolvedValue({ ...DEFAULT_SETTINGS, testCommand: "vitest run", buildCommand: "pnpm build", verificationFixRetries: 2 });
+    await expect(aiMergeTask(store, "/tmp/root", "FN-050")).rejects.toThrow();
+  });
+
+  it("runs full test+build verification after a build-failure fix", async () => {
+    let buildRuns = 0;
+    let statusReads = 0;
+    mockedExecSync.mockImplementation((cmd: any) => {
+      const cmdStr = String(cmd);
+      if (cmdStr.includes("status --porcelain")) return ++statusReads === 1 ? "" : " M src/fix.ts";
+      if (cmdStr.includes("vitest run")) return Buffer.from("");
+      if (cmdStr.includes("pnpm build")) { if (++buildRuns === 1) { const err = new Error("Build failed") as any; err.status = 1; throw err; } return Buffer.from(""); }
+      if (cmdStr.includes("rev-parse --verify")) return Buffer.from("abc123");
+      if (cmdStr === "git rev-parse HEAD" || cmdStr.startsWith("git rev-parse HEAD ")) return "mergedcommit123";
+      if (cmdStr.includes("git log")) return "- feat: something" as any;
+      if (cmdStr.includes("merge-base")) return Buffer.from("abc123");
+      if (cmdStr.includes("git diff") && cmdStr.includes("--stat")) return "1 file changed" as any;
+      if (cmdStr.includes("merge --squash")) return Buffer.from("");
+      if (cmdStr.includes("diff --cached --quiet")) return "1" as any;
+      if (cmdStr.includes("diff --cached")) return "0" as any;
+      return Buffer.from("");
+    });
+    mockedCreateFnAgent.mockResolvedValue({ session: { prompt: vi.fn().mockResolvedValue(undefined), dispose: vi.fn() } } as any);
+    const store = createMockStore({ id: "FN-050", worktree: "/tmp/root/.worktrees/KB-050" }, [{ id: "FN-050", worktree: "/tmp/root/.worktrees/KB-050", column: "in-review" } as Task]);
+    (store.getSettings as ReturnType<typeof vi.fn>).mockResolvedValue({ ...DEFAULT_SETTINGS, testCommand: "vitest run", buildCommand: "pnpm build", verificationFixRetries: 1, buildRetryCount: 0 });
+    await expect(aiMergeTask(store, "/tmp/root", "FN-050")).rejects.toThrow();
+  });
+
+  it("retries when build-failure fix keeps build green but breaks tests in full rerun", async () => {
+    let buildRuns = 0;
+    let statusReads = 0;
+    mockedExecSync.mockImplementation((cmd: any) => {
+      const cmdStr = String(cmd);
+      if (cmdStr.includes("status --porcelain")) return ++statusReads === 1 ? "" : " M src/fix.ts";
+      if (cmdStr.includes("vitest run")) { const err = new Error("Test failed") as any; err.status = 1; throw err; }
+      if (cmdStr.includes("pnpm build")) { if (++buildRuns === 1) { const err = new Error("Build failed") as any; err.status = 1; throw err; } return Buffer.from(""); }
+      if (cmdStr.includes("rev-parse --verify")) return Buffer.from("abc123");
+      if (cmdStr === "git rev-parse HEAD" || cmdStr.startsWith("git rev-parse HEAD ")) return "mergedcommit123";
+      if (cmdStr.includes("git log")) return "- feat: something" as any;
+      if (cmdStr.includes("merge-base")) return Buffer.from("abc123");
+      if (cmdStr.includes("git diff") && cmdStr.includes("--stat")) return "1 file changed" as any;
+      if (cmdStr.includes("merge --squash")) return Buffer.from("");
+      if (cmdStr.includes("diff --cached --quiet")) return "1" as any;
+      if (cmdStr.includes("diff --cached")) return "" as any;
+      return Buffer.from("");
+    });
+    mockedCreateFnAgent.mockResolvedValue({ session: { prompt: vi.fn().mockResolvedValue(undefined), dispose: vi.fn() } } as any);
+    const store = createMockStore({ id: "FN-050", worktree: "/tmp/root/.worktrees/KB-050" }, [{ id: "FN-050", worktree: "/tmp/root/.worktrees/KB-050", column: "in-review" } as Task]);
+    (store.getSettings as ReturnType<typeof vi.fn>).mockResolvedValue({ ...DEFAULT_SETTINGS, testCommand: "vitest run", buildCommand: "pnpm build", verificationFixRetries: 2, buildRetryCount: 0 });
+    await expect(aiMergeTask(store, "/tmp/root", "FN-050")).rejects.toThrow();
+  });
+
   it("logs fix-agent startup metadata, streams callbacks, and logs rerun lifecycle", async () => {
     let capturedFixOptions: any;
 

packages/engine/src/merger.ts

@@ -769,8 +769,10 @@ async function attemptInMergeVerificationFix(
   options: MergerOptions,
   mergeRunContext?: Pick<EngineRunContext, "runId" | "agentId">,
   fixAttemptNumber?: number,
-  _testCommand?: string,
+  testCommand?: string,
-  _buildCommand?: string,
+  buildCommand?: string,
+  testSource?: "explicit" | "inferred",
+  buildSource?: "explicit" | "inferred",
   fixModifiedFiles?: Set<string>,
 ): Promise<boolean> {
   // Snapshot the working tree before doing anything so the diff reflects only
@@ -834,7 +836,7 @@ Do not refactor, rename broadly, or make opportunistic improvements.
 1. Read the error output carefully to understand what is failing before editing anything
 2. Before assuming a code fix is needed, check whether the failure is caused by stale/missing build artifacts in a sibling workspace package — typical signatures: \`Failed to resolve import "./X.js"\` pointing into another package's \`dist/\`, \`Cannot find module\`, or \`ERR_MODULE_NOT_FOUND\` referencing a workspace-internal path. In that case, rebuild the affected package(s) (e.g. \`pnpm --filter <pkg> build\`, or \`pnpm --filter "<scope>/*" build\` for a group) and re-run verification before editing source files.
 3. Make targeted fixes to the failing code path
-4. After fixing, run the verification command to confirm the fix works
+4. After fixing, verify your changes keep both deterministic test and build commands passing
 5. Do NOT make any git commits — just fix the code
 6. You MAY modify any files needed to make the verification pass, including files unrelated to this task's original change. Pre-existing build/test breakage on the base branch is in scope: fix it. Prefer the smallest change that makes verification green.
 7. If you cannot fix the issue within scope, explain why and what evidence indicates a deeper/root problem`,
@@ -897,7 +899,7 @@ ${failureContext.output.slice(0, VERIFICATION_LOG_MAX_CHARS)}
 ## Instructions
 1. Read the error output and identify the root cause
 2. Make targeted fixes to resolve the failure
-3. Run the verification command \`${failureContext.command}\` to confirm your fix works
+3. Use \`${failureContext.command}\` while iterating, but ensure your final changes keep both deterministic test and build commands passing
 4. If the fix doesn't work, try a different approach
 5. Do NOT make any git commits`;
 
@@ -964,16 +966,24 @@ ${failureContext.output.slice(0, VERIFICATION_LOG_MAX_CHARS)}
         undefined,
         "merger",
       );
-      const reRunResult = await runVerificationCommand(
+      try {
-        store,
+        await runDeterministicVerification(
-        rootDir,
+          store,
-        taskId,
+          rootDir,
-        failureContext.command,
+          taskId,
-        failureContext.type,
+          testCommand,
-        options.signal,
+          buildCommand,
-      );
+          testSource,
-
+          buildSource,
-      return reRunResult.success;
+          options.signal,
+        );
+        return true;
+      } catch (error: unknown) {
+        if (error instanceof VerificationError) {
+          return false;
+        }
+        throw error;
+      }
     } finally {
       // Flush buffered output before disposal so fix-attempt activity is visible.
       await logger.flush();
@@ -4973,6 +4983,8 @@ export async function aiMergeTask(
                 fixAttempt,
                 effectiveTestCommand,
                 effectiveBuildCommand,
+                effectiveTestSource,
+                effectiveBuildSource,
                 verificationFixModifiedFiles,
               );
 
@@ -5090,6 +5102,8 @@ export async function aiMergeTask(
               fixAttempt,
               effectiveTestCommand,
               effectiveBuildCommand,
+              effectiveTestSource,
+              effectiveBuildSource,
               buildFixModifiedFiles,
             );