diff --git a/extensions/feishu/src/bot.ts b/extensions/feishu/src/bot.ts
index d47c6d191b02..2ce55d6c4050 100644
--- a/extensions/feishu/src/bot.ts
+++ b/extensions/feishu/src/bot.ts
@@ -1575,7 +1575,7 @@ export async function handleFeishuMessage(params: {
             turnResult.dispatched &&
             shouldSendNoVisibleReplyFallback({
               ...turnResult.dispatchResult,
-              failedCounts: dispatcher.getFailedCounts(),
+              failedCounts: dispatcher.getFailedCounts?.() ?? { tool: 0, block: 0, final: 0 },
             })
           ) {
             await ensureNoVisibleReplyFallback("broadcast-dispatch-complete-no-visible-reply");
@@ -1771,7 +1771,7 @@ export async function handleFeishuMessage(params: {
       if (
         shouldSendNoVisibleReplyFallback({
           ...dispatchResult,
-          failedCounts: dispatcher.getFailedCounts(),
+          failedCounts: dispatcher.getFailedCounts?.() ?? { tool: 0, block: 0, final: 0 },
         })
       ) {
         await ensureNoVisibleReplyFallback("dispatch-complete-no-visible-reply");
diff --git a/src/auto-reply/reply/dispatch-acp-delivery.ts b/src/auto-reply/reply/dispatch-acp-delivery.ts
index 274ebd67696c..04d20375045b 100644
--- a/src/auto-reply/reply/dispatch-acp-delivery.ts
+++ b/src/auto-reply/reply/dispatch-acp-delivery.ts
@@ -16,6 +16,7 @@ import type { FinalizedMsgContext } from "../templating.js";
 import type { ReplyPayload } from "../types.js";
 import { waitForReplyDispatcherIdle } from "./reply-dispatcher.js";
 import type { ReplyDispatchKind, ReplyDispatcher } from "./reply-dispatcher.types.js";
+import { readDispatcherFailedCounts } from "./reply-dispatcher.types.js";
 import { resolveRoutedDeliveryThreadId } from "./routed-delivery-thread.js";
 
 const routeReplyRuntimeLoader = createLazyImportLoader(() => import("./route-reply.runtime.js"));
@@ -257,7 +258,7 @@ export function createAcpDispatchDeliveryCoordinator(params: {
     state.settledDirectVisibleText = true;
     hasPendingDirectBlockReplyDelivery = false;
     await params.dispatcher.waitForIdle();
-    const failedCounts = params.dispatcher.getFailedCounts();
+    const failedCounts = readDispatcherFailedCounts(params.dispatcher);
     const failedVisibleCount = failedCounts.block + failedCounts.final;
     if (failedVisibleCount > 0) {
       state.failedVisibleTextDelivery = true;
diff --git a/src/auto-reply/reply/dispatch-from-config.final-outcome-counts.test.ts b/src/auto-reply/reply/dispatch-from-config.final-outcome-counts.test.ts
new file mode 100644
index 000000000000..fccf77ea6855
--- /dev/null
+++ b/src/auto-reply/reply/dispatch-from-config.final-outcome-counts.test.ts
@@ -0,0 +1,35 @@
+import { describe, expect, it } from "vitest";
+import { getDispatcherFinalOutcomeCounts } from "./dispatch-from-config.js";
+import type { ReplyDispatcher } from "./reply-dispatcher.types.js";
+
+describe("getDispatcherFinalOutcomeCounts (#89116)", () => {
+  it("returns failed: 0 when the dispatcher does not implement getFailedCounts", () => {
+    // Some ReplyDispatcher variants omit the optional count methods entirely; the
+    // previous code called dispatcher.getFailedCounts() unguarded and threw
+    // "TypeError: dispatcher.getFailedCounts is not a function".
+    const dispatcher = {
+      getCancelledCounts: () => ({ tool: 0, block: 0, final: 2 }),
+      // getFailedCounts intentionally absent
+    } as unknown as ReplyDispatcher;
+
+    expect(() => getDispatcherFinalOutcomeCounts(dispatcher)).not.toThrow();
+    expect(getDispatcherFinalOutcomeCounts(dispatcher)).toEqual({ cancelled: 2, failed: 0 });
+  });
+
+  it("returns cancelled: 0 when getCancelledCounts is absent (existing behavior preserved)", () => {
+    const dispatcher = {
+      getFailedCounts: () => ({ tool: 0, block: 1, final: 3 }),
+    } as unknown as ReplyDispatcher;
+
+    expect(getDispatcherFinalOutcomeCounts(dispatcher)).toEqual({ cancelled: 0, failed: 3 });
+  });
+
+  it("uses the real final counts when both methods are present", () => {
+    const dispatcher = {
+      getCancelledCounts: () => ({ tool: 0, block: 0, final: 1 }),
+      getFailedCounts: () => ({ tool: 0, block: 0, final: 5 }),
+    } as unknown as ReplyDispatcher;
+
+    expect(getDispatcherFinalOutcomeCounts(dispatcher)).toEqual({ cancelled: 1, failed: 5 });
+  });
+});
diff --git a/src/auto-reply/reply/dispatch-from-config.ts b/src/auto-reply/reply/dispatch-from-config.ts
index b9714a7b9eae..6b5f99771344 100644
--- a/src/auto-reply/reply/dispatch-from-config.ts
+++ b/src/auto-reply/reply/dispatch-from-config.ts
@@ -132,7 +132,12 @@ import { withFullRuntimeReplyConfig } from "./get-reply-fast-path.js";
 import { claimInboundDedupe, commitInboundDedupe, releaseInboundDedupe } from "./inbound-dedupe.js";
 import { resolveOriginMessageProvider } from "./origin-routing.js";
 import { waitForReplyDispatcherIdle } from "./reply-dispatcher.js";
-import type { ReplyDispatchKind, ReplyDispatcher } from "./reply-dispatcher.types.js";
+import type {
+  DispatcherOutcomeCountsView,
+  ReplyDispatchKind,
+  ReplyDispatcher,
+} from "./reply-dispatcher.types.js";
+import { readDispatcherFailedCounts } from "./reply-dispatcher.types.js";
 import { replyRunRegistry, type ReplyOperation } from "./reply-run-registry.js";
 import { isReplyProfilerEnabled } from "./reply-timing-tracker.js";
 import { admitReplyTurn, resolveReplyTurnKind } from "./reply-turn-admission.js";
@@ -774,13 +779,13 @@ async function mirrorInternalSourceReplyToTranscript(params: {
   }
 }
 
-function getDispatcherFinalOutcomeCounts(dispatcher: ReplyDispatcher): {
+export function getDispatcherFinalOutcomeCounts(dispatcher: DispatcherOutcomeCountsView): {
   cancelled: number;
   failed: number;
 } {
   return {
     cancelled: dispatcher.getCancelledCounts?.().final ?? 0,
-    failed: dispatcher.getFailedCounts().final,
+    failed: readDispatcherFailedCounts(dispatcher).final,
   };
 }
 
@@ -903,7 +908,7 @@ function createAbortAwareDispatcher(params: {
     sendFinalReply: sendIfActive(params.dispatcher.sendFinalReply),
     waitForIdle: () => params.dispatcher.waitForIdle(),
     getQueuedCounts: () => params.dispatcher.getQueuedCounts(),
-    getFailedCounts: () => params.dispatcher.getFailedCounts(),
+    getFailedCounts: () => readDispatcherFailedCounts(params.dispatcher),
     markComplete: () => {
       if (!params.isAborted()) {
         params.dispatcher.markComplete();
diff --git a/src/auto-reply/reply/reply-dispatcher.types.ts b/src/auto-reply/reply/reply-dispatcher.types.ts
index 1dd77582d263..c7d4e1064664 100644
--- a/src/auto-reply/reply/reply-dispatcher.types.ts
+++ b/src/auto-reply/reply/reply-dispatcher.types.ts
@@ -18,3 +18,21 @@ export type ReplyDispatcher = {
   getFailedCounts: () => Record<ReplyDispatchKind, number>;
   markComplete: () => void;
 };
+
+/**
+ * Internal view for defensive outcome-count accounting. Some non-conforming
+ * runtime dispatcher variants (for example plugin-provided dispatchers) may omit
+ * these readers even though the public ReplyDispatcher contract requires
+ * getFailedCounts. Read the counters through this view so the guards stay
+ * type-correct without weakening the SDK-visible ReplyDispatcher type.
+ */
+export type DispatcherOutcomeCountsView = {
+  getCancelledCounts?: () => Record<ReplyDispatchKind, number>;
+  getFailedCounts?: () => Record<ReplyDispatchKind, number>;
+};
+
+export function readDispatcherFailedCounts(
+  dispatcher: DispatcherOutcomeCountsView,
+): Record<ReplyDispatchKind, number> {
+  return dispatcher.getFailedCounts?.() ?? { tool: 0, block: 0, final: 0 };
+}