feat(FN-4545): complete Step 1 — extend auto-recovery failure taxonomy

Fusion-Task-Id: FN-4545
Fusion-Task-Lineage: 95108429-618e-4a6d-9fa9-7ac2596665a2

packages/core/src/types.ts

@@ -234,7 +234,8 @@ export type AutoRecoveryFailureClass =
   | "branch-cross-contamination"
   | "branch-conflict-tripwire"
   | "branch-conflict-recovery-exhausted"
-  | "branch-conflict-unrecoverable";
+  | "branch-conflict-unrecoverable"
+  | "message-delivery-failure";
 
 export interface AutoRecoverySettings {
   mode: AutoRecoveryMode;
@@ -265,6 +266,7 @@ export function normalizeAutoRecovery(value: unknown): AutoRecoverySettings {
             "branch-conflict-tripwire",
             "branch-conflict-recovery-exhausted",
             "branch-conflict-unrecoverable",
+            "message-delivery-failure",
           ].includes(k)
           && typeof v === "string"
           && (AUTO_RECOVERY_MODES as readonly string[]).includes(v)

packages/engine/src/__tests__/auto-recovery.test.ts

@@ -20,6 +20,7 @@ const classes: AutoRecoveryFailure["class"][] = [
   "branch-conflict-tripwire",
   "branch-conflict-recovery-exhausted",
   "branch-conflict-unrecoverable",
+  "message-delivery-failure",
 ];
 
 describe("auto-recovery dispatcher", () => {
@@ -68,6 +69,21 @@ describe("auto-recovery dispatcher", () => {
     expect(decision.rationale).toBe("destructive-ambiguity");
   });
 
+  it.each([
+    ["off", "pause"],
+    ["deterministic-only", "pause"],
+    ["programmatic", "retry"],
+    ["ai-assisted", "retry"],
+  ] as const)("message-delivery-failure routes %s to %s", (mode, expectedAction) => {
+    const { dispatcher } = createDispatcher();
+    const decision = dispatcher.classify({ class: "message-delivery-failure", taskId: "FN-1", pausedReason: "message-delivery-failure" }, {
+      task,
+      retryCount: 0,
+      settings: { mode, maxRetries: 3 },
+    });
+    expect(decision.action).toBe(expectedAction);
+  });
+
   it("dispatch falls back to pause when handler missing", async () => {
     const { dispatcher, database } = createDispatcher();
     const decision = await dispatcher.dispatch({ class: "branch-conflict-unrecoverable", taskId: "FN-1", pausedReason: "branch-conflict-unrecoverable" }, {