diff --git a/packages/engine/src/__tests__/reliability-interactions/post-done-continuation-no-wedge.test.ts b/packages/engine/src/__tests__/reliability-interactions/post-done-continuation-no-wedge.test.ts
index 57f840621d..8f7d90e73f 100644
--- a/packages/engine/src/__tests__/reliability-interactions/post-done-continuation-no-wedge.test.ts
+++ b/packages/engine/src/__tests__/reliability-interactions/post-done-continuation-no-wedge.test.ts
@@ -301,6 +301,78 @@ describe("FN-5866 reliability interactions: post-done continuation no wedge", ()
     manager.stop();
   });
 
+  it("self-heals Codex transcript-desync post-done wedges without swallowing generic 400s", async () => {
+    const codexEnvelope = "Codex error: " + JSON.stringify({
+      type: "error",
+      error: {
+        type: "invalid_request_error",
+        message: "No tool call found for function call output with call_id call_2KewW55MyBgwZoNtMubFNpUb.",
+        param: "input",
+      },
+      status: 400,
+    });
+    const symmetricLogEvidence = "No function call found for function call output with call_id call_2KewW55MyBgwZoNtMubFNpUb.";
+    const envelopeWedged = makeTask({
+      id: "FN-6594-CODEX-ENVELOPE-WEDGED",
+      column: "in-review",
+      status: "failed",
+      error: codexEnvelope,
+      steps: [{ name: "Implement", status: "done" as const }],
+      log: [{ timestamp: new Date(Date.now() - 60_000).toISOString(), action: "Task marked done by agent" } as any],
+    });
+    const logEvidenceWedged = makeTask({
+      id: "FN-6594-CODEX-LOG-WEDGED",
+      column: "in-review",
+      status: "failed",
+      error: "Session failed while replaying transcript",
+      steps: [{ name: "Implement", status: "done" as const }],
+      log: [
+        { timestamp: new Date(Date.now() - 60_000).toISOString(), action: "Task marked done by agent" } as any,
+        {
+          timestamp: new Date(Date.now() - 30_000).toISOString(),
+          action: "executor post-done continuation failed",
+          outcome: symmetricLogEvidence,
+        } as any,
+      ],
+    });
+    const badInputWedged = makeTask({
+      id: "FN-6594-BAD-INPUT-WEDGED",
+      column: "in-review",
+      status: "failed",
+      error: "400 invalid_request_error: invalid temperature",
+      steps: [{ name: "Implement", status: "done" as const }],
+      log: [
+        { timestamp: new Date(Date.now() - 60_000).toISOString(), action: "Task marked done by agent" } as any,
+        { timestamp: new Date(Date.now() - 30_000).toISOString(), action: "quota exceeded" } as any,
+      ],
+    });
+    const store = createSelfHealingStore([envelopeWedged, logEvidenceWedged, badInputWedged]);
+    const manager = new SelfHealingManager(store, { rootDir: "/tmp/repo" });
+
+    expect(await manager.recoverPostDoneNonContinuableWedge()).toBe(2);
+
+    for (const recovered of [envelopeWedged, logEvidenceWedged]) {
+      expect(recovered.column).toBe("in-review");
+      expect(recovered.status).toBeUndefined();
+      expect(recovered.error).toBeUndefined();
+      expect(recovered.completionHandoffLimboRecoveryCount).toBe(1);
+      expect(
+        (recovered.log ?? []).some((entry: any) => entry.action.includes("Auto-recovered completed-task non-continuable wedge")),
+      ).toBe(true);
+      expect(
+        ((store as any).__audits as any[]).some(
+          (event: any) => event.mutationType === "task:auto-recover-post-done-noncontinuable-wedge" && event.target === recovered.id,
+        ),
+      ).toBe(true);
+    }
+
+    expect(badInputWedged.status).toBe("failed");
+    expect(badInputWedged.error).toBe("400 invalid_request_error: invalid temperature");
+    expect(badInputWedged.completionHandoffLimboRecoveryCount).toBeUndefined();
+    expect(((store as any).__audits as any[]).some((event: any) => event.target === badInputWedged.id)).toBe(false);
+    manager.stop();
+  });
+
   it("falls through to terminal failure after the non-continuable fresh-session retry budget is exhausted", async () => {
     const task = makeTask({
       id: "FN-5866-INCOMPLETE-EXHAUSTED",
diff --git a/packages/engine/src/__tests__/transient-error-detector.test.ts b/packages/engine/src/__tests__/transient-error-detector.test.ts
index cc8a6328ad..80de2ab1d9 100644
--- a/packages/engine/src/__tests__/transient-error-detector.test.ts
+++ b/packages/engine/src/__tests__/transient-error-detector.test.ts
@@ -316,13 +316,35 @@ describe("Transient Error Detector", () => {
         .toBe(true);
     });
 
-    it("returns false for unrelated and provider role-validation errors", () => {
+    it("returns true for Codex transcript-desync errors", () => {
+      expect(
+        isNonContinuableSessionError(
+          "No tool call found for function call output with call_id call_2KewW55MyBgwZoNtMubFNpUb.",
+        ),
+      ).toBe(true);
+      expect(
+        isNonContinuableSessionError(
+          'Codex error: {"type":"error","error":{"type":"invalid_request_error","message":"No tool call found for function call output with call_id call_2KewW55MyBgwZoNtMubFNpUb.","param":"input"},"status":400}',
+        ),
+      ).toBe(true);
+      expect(
+        isNonContinuableSessionError(
+          "No function call found for function call output with call_id call_2KewW55MyBgwZoNtMubFNpUb.",
+        ),
+      ).toBe(true);
+    });
+
+    it("returns false for unrelated, operator-actionable, and ordinary bad-input errors", () => {
       expect(isNonContinuableSessionError("socket hang up")).toBe(false);
       expect(
         isNonContinuableSessionError(
           "developer is not one of ['system', 'assistant', 'user', 'tool', 'function'] - 'messages.[0].role'",
         ),
       ).toBe(false);
+      expect(isNonContinuableSessionError("invalid api key")).toBe(false);
+      expect(isNonContinuableSessionError("quota exceeded")).toBe(false);
+      expect(isNonContinuableSessionError("billing issue: quota exceeded")).toBe(false);
+      expect(isNonContinuableSessionError("400 invalid_request_error: invalid temperature")).toBe(false);
     });
   });
 
diff --git a/packages/engine/src/transient-error-detector.ts b/packages/engine/src/transient-error-detector.ts
index 1c86a25c1c..3362fe041a 100644
--- a/packages/engine/src/transient-error-detector.ts
+++ b/packages/engine/src/transient-error-detector.ts
@@ -193,6 +193,11 @@ export function extractMissingModulePath(errorMessage: string): string | null {
 
 const UNSUPPORTED_MESSAGE_ROLE_PATTERN = /\bmessages\.\[\d+\]\.role\b[\s\S]*\bis not one of\b|\bis not one of\b[\s\S]*\bmessages\.\[\d+\]\.role\b/i;
 const NON_CONTINUABLE_SESSION_PATTERN = /cannot continue from message role\s*[:=-]?\s*(?:['"`]?)(assistant|tool|function|system|user)(?:['"`]?)\b/i;
+/*
+FNXC:Reliability-ErrorClassification 2026-06-17-14:48:
+FN-6594 treats Codex transcript-desync on post-done session re-entry as non-continuable when a `function_call_output` is replayed without its `function_call`, or the symmetric function-call/output pair is missing. Anchor on the original `No tool call found for function call output with call_id ...` symptom so executor fresh-session retry and self-healing post-done wedge recovery engage without swallowing generic 400/auth/quota errors.
+*/
+const CODEX_TRANSCRIPT_DESYNC_NON_CONTINUABLE_PATTERN = /\bno\s+(?:tool\s+call|function\s+call)\s+found\s+for\s+function\s+call\s+output\b/i;
 const MODEL_AUTH_TIER_INCOMPATIBILITY_PATTERNS: RegExp[] = [
   // Codex ChatGPT-account auth-tier incompatibility: the model is valid, but
   // unavailable for the current auth tier.
@@ -228,7 +233,7 @@ export function isNonContinuableSessionError(errorMessage: string): boolean {
   if (!errorMessage || typeof errorMessage !== "string") {
     return false;
   }
-  return NON_CONTINUABLE_SESSION_PATTERN.test(errorMessage);
+  return NON_CONTINUABLE_SESSION_PATTERN.test(errorMessage) || CODEX_TRANSCRIPT_DESYNC_NON_CONTINUABLE_PATTERN.test(errorMessage);
 }
 
 const OPERATOR_ACTIONABLE_AGENT_ERROR_PATTERNS: RegExp[] = [