fix: stop hardcoded channel fallback and auto-pick sole configured channel (#23357) (thanks @lbo728)

Co-authored-by: lbo728 <extreme0728@gmail.com>

src/gateway/server-methods/agent.ts

@@ -15,6 +15,7 @@ import {
   resolveAgentDeliveryPlan,
   resolveAgentOutboundTarget,
 } from "../../infra/outbound/agent-delivery.js";
+import { resolveMessageChannelSelection } from "../../infra/outbound/channel-selection.js";
 import { classifySessionKeyShape, normalizeAgentId } from "../../routing/session-key.js";
 import { defaultRuntime } from "../../runtime.js";
 import { normalizeInputProvenance, type InputProvenance } from "../../sessions/input-provenance.js";
@@ -490,17 +491,36 @@ export const agentHandlers: GatewayRequestHandlers = {
       wantsDelivery,
     });
 
-    const resolvedChannel = deliveryPlan.resolvedChannel;
-    const deliveryTargetMode = deliveryPlan.deliveryTargetMode;
-    const resolvedAccountId = deliveryPlan.resolvedAccountId;
+    let resolvedChannel = deliveryPlan.resolvedChannel;
+    let deliveryTargetMode = deliveryPlan.deliveryTargetMode;
+    let resolvedAccountId = deliveryPlan.resolvedAccountId;
     let resolvedTo = deliveryPlan.resolvedTo;
+    let effectivePlan = deliveryPlan;
+
+    if (wantsDelivery && resolvedChannel === INTERNAL_MESSAGE_CHANNEL) {
+      const cfgResolved = cfgForAgent ?? cfg;
+      try {
+        const selection = await resolveMessageChannelSelection({ cfg: cfgResolved });
+        resolvedChannel = selection.channel;
+        deliveryTargetMode = deliveryTargetMode ?? "implicit";
+        effectivePlan = {
+          ...deliveryPlan,
+          resolvedChannel,
+          deliveryTargetMode,
+          resolvedAccountId,
+        };
+      } catch (err) {
+        respond(false, undefined, errorShape(ErrorCodes.INVALID_REQUEST, String(err)));
+        return;
+      }
+    }
 
     if (!resolvedTo && isDeliverableMessageChannel(resolvedChannel)) {
       const cfgResolved = cfgForAgent ?? cfg;
       const fallback = resolveAgentOutboundTarget({
         cfg: cfgResolved,
-        plan: deliveryPlan,
-        targetMode: "implicit",
+        plan: effectivePlan,
+        targetMode: deliveryTargetMode ?? "implicit",
         validateExplicitTarget: false,
       });
       if (fallback.resolvedTarget?.ok) {
@@ -508,6 +528,18 @@ export const agentHandlers: GatewayRequestHandlers = {
       }
     }
 
+    if (wantsDelivery && resolvedChannel === INTERNAL_MESSAGE_CHANNEL) {
+      respond(
+        false,
+        undefined,
+        errorShape(
+          ErrorCodes.INVALID_REQUEST,
+          "delivery channel is required: pass --channel/--reply-channel or use a main session with a previous channel",
+        ),
+      );
+      return;
+    }
+
     const deliver = request.deliver === true && resolvedChannel !== INTERNAL_MESSAGE_CHANNEL;
 
     const accepted = {

src/gateway/server-methods/send.test.ts

@@ -8,6 +8,8 @@ const mocks = vi.hoisted(() => ({
   appendAssistantMessageToSessionTranscript: vi.fn(async () => ({ ok: true, sessionFile: "x" })),
   recordSessionMetaFromInbound: vi.fn(async () => ({ ok: true })),
   resolveOutboundTarget: vi.fn(() => ({ ok: true, to: "resolved" })),
+  resolveMessageChannelSelection: vi.fn(),
+  sendPoll: vi.fn(async () => ({ messageId: "poll-1" })),
 }));
 
 vi.mock("../../config/config.js", async () => {
@@ -20,7 +22,7 @@ vi.mock("../../config/config.js", async () => {
 });
 
 vi.mock("../../channels/plugins/index.js", () => ({
-  getChannelPlugin: () => ({ outbound: {} }),
+  getChannelPlugin: () => ({ outbound: { sendPoll: mocks.sendPoll } }),
   normalizeChannelId: (value: string) => (value === "webchat" ? null : value),
 }));
 
@@ -28,6 +30,10 @@ vi.mock("../../infra/outbound/targets.js", () => ({
   resolveOutboundTarget: mocks.resolveOutboundTarget,
 }));
 
+vi.mock("../../infra/outbound/channel-selection.js", () => ({
+  resolveMessageChannelSelection: mocks.resolveMessageChannelSelection,
+}));
+
 vi.mock("../../infra/outbound/deliver.js", () => ({
   deliverOutboundPayloads: mocks.deliverOutboundPayloads,
 }));
@@ -61,6 +67,19 @@ async function runSend(params: Record<string, unknown>) {
   return { respond };
 }
 
+async function runPoll(params: Record<string, unknown>) {
+  const respond = vi.fn();
+  await sendHandlers.poll({
+    params: params as never,
+    respond,
+    context: makeContext(),
+    req: { type: "req", id: "1", method: "poll" },
+    client: null,
+    isWebchatConnect: () => false,
+  });
+  return { respond };
+}
+
 function mockDeliverySuccess(messageId: string) {
   mocks.deliverOutboundPayloads.mockResolvedValue([{ messageId, channel: "slack" }]);
 }
@@ -69,6 +88,11 @@ describe("gateway send mirroring", () => {
   beforeEach(() => {
     vi.clearAllMocks();
     mocks.resolveOutboundTarget.mockReturnValue({ ok: true, to: "resolved" });
+    mocks.resolveMessageChannelSelection.mockResolvedValue({
+      channel: "slack",
+      configured: ["slack"],
+    });
+    mocks.sendPoll.mockResolvedValue({ messageId: "poll-1" });
   });
 
   it("accepts media-only sends without message", async () => {
@@ -137,6 +161,81 @@ describe("gateway send mirroring", () => {
     );
   });
 
+  it("auto-picks the single configured channel for send", async () => {
+    mockDeliverySuccess("m-single-send");
+
+    const { respond } = await runSend({
+      to: "x",
+      message: "hi",
+      idempotencyKey: "idem-missing-channel",
+    });
+
+    expect(mocks.resolveMessageChannelSelection).toHaveBeenCalled();
+    expect(mocks.deliverOutboundPayloads).toHaveBeenCalled();
+    expect(respond).toHaveBeenCalledWith(
+      true,
+      expect.objectContaining({ messageId: "m-single-send" }),
+      undefined,
+      expect.objectContaining({ channel: "slack" }),
+    );
+  });
+
+  it("returns invalid request when send channel selection is ambiguous", async () => {
+    mocks.resolveMessageChannelSelection.mockRejectedValueOnce(
+      new Error("Channel is required when multiple channels are configured: telegram, slack"),
+    );
+
+    const { respond } = await runSend({
+      to: "x",
+      message: "hi",
+      idempotencyKey: "idem-missing-channel-ambiguous",
+    });
+
+    expect(mocks.deliverOutboundPayloads).not.toHaveBeenCalled();
+    expect(respond).toHaveBeenCalledWith(
+      false,
+      undefined,
+      expect.objectContaining({
+        message: expect.stringContaining("Channel is required"),
+      }),
+    );
+  });
+
+  it("auto-picks the single configured channel for poll", async () => {
+    const { respond } = await runPoll({
+      to: "x",
+      question: "Q?",
+      options: ["A", "B"],
+      idempotencyKey: "idem-poll-missing-channel",
+    });
+
+    expect(mocks.resolveMessageChannelSelection).toHaveBeenCalled();
+    expect(respond).toHaveBeenCalledWith(true, expect.any(Object), undefined, {
+      channel: "slack",
+    });
+  });
+
+  it("returns invalid request when poll channel selection is ambiguous", async () => {
+    mocks.resolveMessageChannelSelection.mockRejectedValueOnce(
+      new Error("Channel is required when multiple channels are configured: telegram, slack"),
+    );
+
+    const { respond } = await runPoll({
+      to: "x",
+      question: "Q?",
+      options: ["A", "B"],
+      idempotencyKey: "idem-poll-missing-channel-ambiguous",
+    });
+
+    expect(respond).toHaveBeenCalledWith(
+      false,
+      undefined,
+      expect.objectContaining({
+        message: expect.stringContaining("Channel is required"),
+      }),
+    );
+  });
+
   it("does not mirror when delivery returns no results", async () => {
     mocks.deliverOutboundPayloads.mockResolvedValue([]);
 

src/gateway/server-methods/send.ts

@@ -1,8 +1,8 @@
 import { resolveSessionAgentId } from "../../agents/agent-scope.js";
 import { getChannelPlugin, normalizeChannelId } from "../../channels/plugins/index.js";
-import { DEFAULT_CHAT_CHANNEL } from "../../channels/registry.js";
 import { createOutboundSendDeps } from "../../cli/deps.js";
 import { loadConfig } from "../../config/config.js";
+import { resolveMessageChannelSelection } from "../../infra/outbound/channel-selection.js";
 import { deliverOutboundPayloads } from "../../infra/outbound/deliver.js";
 import {
   ensureOutboundSessionEntry,
@@ -126,7 +126,16 @@ export const sendHandlers: GatewayRequestHandlers = {
       );
       return;
     }
-    const channel = normalizedChannel ?? DEFAULT_CHAT_CHANNEL;
+    const cfg = loadConfig();
+    let channel = normalizedChannel;
+    if (!channel) {
+      try {
+        channel = (await resolveMessageChannelSelection({ cfg })).channel;
+      } catch (err) {
+        respond(false, undefined, errorShape(ErrorCodes.INVALID_REQUEST, String(err)));
+        return;
+      }
+    }
     const accountId =
       typeof request.accountId === "string" && request.accountId.trim().length
         ? request.accountId.trim()
@@ -148,7 +157,6 @@ export const sendHandlers: GatewayRequestHandlers = {
 
     const work = (async (): Promise<InflightResult> => {
       try {
-        const cfg = loadConfig();
         const resolved = resolveOutboundTarget({
           channel: outboundChannel,
           to,
@@ -324,7 +332,16 @@ export const sendHandlers: GatewayRequestHandlers = {
       );
       return;
     }
-    const channel = normalizedChannel ?? DEFAULT_CHAT_CHANNEL;
+    const cfg = loadConfig();
+    let channel = normalizedChannel;
+    if (!channel) {
+      try {
+        channel = (await resolveMessageChannelSelection({ cfg })).channel;
+      } catch (err) {
+        respond(false, undefined, errorShape(ErrorCodes.INVALID_REQUEST, String(err)));
+        return;
+      }
+    }
     if (typeof request.durationSeconds === "number" && channel !== "telegram") {
       respond(
         false,
@@ -370,7 +387,6 @@ export const sendHandlers: GatewayRequestHandlers = {
         );
         return;
       }
-      const cfg = loadConfig();
       const resolved = resolveOutboundTarget({
         channel: channel,
         to,