fix(auto-reply): never allow silent replies for mentioned group turns

The default group silentReply policy sanctions silence for ambient chatter,
which also swallowed empty completions on turns that explicitly mentioned the
bot - the reported production failure. A mention is a directed turn: treat it
like a direct chat and let the no-visible-reply fallback fire. Proven live:
group mention + empty completion delivers exactly one fallback message; ambient
group turns stay silent; normal replies produce no fallback.

src/auto-reply/reply/dispatch-from-config.hooks-and-send-policy.test-utils.ts

@@ -425,6 +425,56 @@ describe("sendPolicy deny — suppress delivery, not processing (#53328)", () =>
     expect(result.noVisibleReplyFallbackEligible).toBeUndefined();
   });
 
+  it("delivers fallback for mentioned group turns even when group silence is allowed", async () => {
+    setNoAbort();
+    const dispatcher = createDispatcher();
+    const replyResolver = vi.fn(async () => undefined);
+    const ctx = buildTestCtx({
+      ChatType: "group",
+      Surface: "telegram",
+      Provider: "telegram",
+      SessionKey: "agent:main:telegram:group:oc_group",
+      WasMentioned: true,
+    });
+
+    // No silentReply config: group default is "allow", but an explicit mention
+    // is a directed turn and must never end silently.
+    const result = await dispatchReplyFromConfig({
+      ctx,
+      cfg: emptyConfig,
+      dispatcher,
+      replyResolver,
+    });
+
+    expect(dispatcher.sendFinalReply).toHaveBeenCalledWith({
+      text: NO_VISIBLE_REPLY_FALLBACK_TEXT,
+    });
+    expect(result.noVisibleReplyFallbackDelivered).toBe(true);
+  });
+
+  it("keeps ambient group turns silent under the default group policy", async () => {
+    setNoAbort();
+    const dispatcher = createDispatcher();
+    const replyResolver = vi.fn(async () => undefined);
+    const ctx = buildTestCtx({
+      ChatType: "group",
+      Surface: "telegram",
+      Provider: "telegram",
+      SessionKey: "agent:main:telegram:group:oc_group",
+    });
+
+    const result = await dispatchReplyFromConfig({
+      ctx,
+      cfg: emptyConfig,
+      dispatcher,
+      replyResolver,
+    });
+
+    expect(dispatcher.sendFinalReply).not.toHaveBeenCalled();
+    expect(result.noVisibleReplyFallbackDelivered).toBeUndefined();
+    expect(result.noVisibleReplyFallbackEligible).toBeUndefined();
+  });
+
   it("does not deliver no-visible fallback when silentReply allows empty finals", async () => {
     setNoAbort();
     const dispatcher = createDispatcher();

src/auto-reply/reply/dispatch-from-config.prepare-context.ts

@@ -224,7 +224,11 @@ export async function prepareDispatchOperationContext(state: PrepareDispatchDeli
   const chatType = normalizeChatType(ctx.ChatType);
   const silentReplyConversationType = resolveRoutedPolicyConversationType(ctx);
   const silentReplySurface = normalizeLowercaseStringOrEmpty(ctx.Surface ?? ctx.Provider);
+  // Group silent-reply policy sanctions silence for ambient chatter only. A turn
+  // that explicitly addressed the bot (mention) must never end silently, matching
+  // the hard-coded direct-chat rule in resolveSilentReplyPolicyFromPolicies.
   const emptyFinalAllowedAsSilent =
+    ctx.WasMentioned !== true &&
     silentReplyConversationType !== undefined &&
     resolveSilentReplyPolicyFromPolicies({
       conversationType: silentReplyConversationType,