Agents: fix subagent completion thread routing

src/gateway/protocol/schema/agent.ts

@@ -22,6 +22,8 @@ export const SendParamsSchema = Type.Object(
     gifPlayback: Type.Optional(Type.Boolean()),
     channel: Type.Optional(Type.String()),
     accountId: Type.Optional(Type.String()),
+    /** Thread id (channel-specific meaning, e.g. Telegram forum topic id). */
+    threadId: Type.Optional(Type.String()),
     /** Optional session key for mirroring delivered output back into the transcript. */
     sessionKey: Type.Optional(Type.String()),
     idempotencyKey: NonEmptyString,

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

@@ -235,4 +235,22 @@ describe("gateway send mirroring", () => {
       }),
     );
   });
+
+  it("forwards threadId to outbound delivery when provided", async () => {
+    mocks.deliverOutboundPayloads.mockResolvedValue([{ messageId: "m-thread", channel: "slack" }]);
+
+    await runSend({
+      to: "channel:C1",
+      message: "hi",
+      channel: "slack",
+      threadId: "1710000000.9999",
+      idempotencyKey: "idem-thread",
+    });
+
+    expect(mocks.deliverOutboundPayloads).toHaveBeenCalledWith(
+      expect.objectContaining({
+        threadId: "1710000000.9999",
+      }),
+    );
+  });
 });

src/gateway/server-methods/send.ts

@@ -64,6 +64,7 @@ export const sendHandlers: GatewayRequestHandlers = {
       gifPlayback?: boolean;
       channel?: string;
       accountId?: string;
+      threadId?: string;
       sessionKey?: string;
       idempotencyKey: string;
     };
@@ -130,6 +131,10 @@ export const sendHandlers: GatewayRequestHandlers = {
       typeof request.accountId === "string" && request.accountId.trim().length
         ? request.accountId.trim()
         : undefined;
+    const threadId =
+      typeof request.threadId === "string" && request.threadId.trim().length
+        ? request.threadId.trim()
+        : undefined;
     const outboundChannel = channel;
     const plugin = getChannelPlugin(channel);
     if (!plugin) {
@@ -182,6 +187,7 @@ export const sendHandlers: GatewayRequestHandlers = {
               agentId: derivedAgentId,
               accountId,
               target: resolved.to,
+              threadId,
             })
           : null;
         if (derivedRoute) {
@@ -203,6 +209,7 @@ export const sendHandlers: GatewayRequestHandlers = {
             ? resolveSessionAgentId({ sessionKey: providedSessionKey, config: cfg })
             : derivedAgentId,
           gifPlayback: request.gifPlayback,
+          threadId: threadId ?? null,
           deps: outboundDeps,
           mirror: providedSessionKey
             ? {