fix: normalize session keys and outbound mirroring

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

@@ -6,6 +6,7 @@ import { sendHandlers } from "./send.js";
 const mocks = vi.hoisted(() => ({
   deliverOutboundPayloads: vi.fn(),
   appendAssistantMessageToSessionTranscript: vi.fn(async () => ({ ok: true, sessionFile: "x" })),
+  recordSessionMetaFromInbound: vi.fn(async () => ({ ok: true })),
 }));
 
 vi.mock("../../config/config.js", async () => {
@@ -37,6 +38,7 @@ vi.mock("../../config/sessions.js", async () => {
   return {
     ...actual,
     appendAssistantMessageToSessionTranscript: mocks.appendAssistantMessageToSessionTranscript,
+    recordSessionMetaFromInbound: mocks.recordSessionMetaFromInbound,
   };
 });
 
@@ -134,4 +136,33 @@ describe("gateway send mirroring", () => {
       }),
     );
   });
+
+  it("derives a target session key when none is provided", async () => {
+    mocks.deliverOutboundPayloads.mockResolvedValue([{ messageId: "m3", channel: "slack" }]);
+
+    const respond = vi.fn();
+    await sendHandlers.send({
+      params: {
+        to: "channel:C1",
+        message: "hello",
+        channel: "slack",
+        idempotencyKey: "idem-4",
+      },
+      respond,
+      context: makeContext(),
+      req: { type: "req", id: "1", method: "send" },
+      client: null,
+      isWebchatConnect: () => false,
+    });
+
+    expect(mocks.recordSessionMetaFromInbound).toHaveBeenCalled();
+    expect(mocks.deliverOutboundPayloads).toHaveBeenCalledWith(
+      expect.objectContaining({
+        mirror: expect.objectContaining({
+          sessionKey: "agent:main:slack:channel:resolved",
+          agentId: "main",
+        }),
+      }),
+    );
+  });
 });

src/gateway/server-methods/send.ts

@@ -5,6 +5,10 @@ import { loadConfig } from "../../config/config.js";
 import { createOutboundSendDeps } from "../../cli/deps.js";
 import { deliverOutboundPayloads } from "../../infra/outbound/deliver.js";
 import { normalizeReplyPayloadsForDelivery } from "../../infra/outbound/payloads.js";
+import {
+  ensureOutboundSessionEntry,
+  resolveOutboundSessionRoute,
+} from "../../infra/outbound/outbound-session.js";
 import { resolveSessionAgentId } from "../../agents/agent-scope.js";
 import type { OutboundChannel } from "../../infra/outbound/targets.js";
 import { resolveOutboundTarget } from "../../infra/outbound/targets.js";
@@ -139,6 +143,30 @@ export const sendHandlers: GatewayRequestHandlers = {
         const mirrorMediaUrls = mirrorPayloads.flatMap(
           (payload) => payload.mediaUrls ?? (payload.mediaUrl ? [payload.mediaUrl] : []),
         );
+        const providedSessionKey =
+          typeof request.sessionKey === "string" && request.sessionKey.trim()
+            ? request.sessionKey.trim()
+            : undefined;
+        const derivedAgentId = resolveSessionAgentId({ config: cfg });
+        // If callers omit sessionKey, derive a target session key from the outbound route.
+        const derivedRoute = !providedSessionKey
+          ? await resolveOutboundSessionRoute({
+              cfg,
+              channel,
+              agentId: derivedAgentId,
+              accountId,
+              target: resolved.to,
+            })
+          : null;
+        if (derivedRoute) {
+          await ensureOutboundSessionEntry({
+            cfg,
+            agentId: derivedAgentId,
+            channel,
+            accountId,
+            route: derivedRoute,
+          });
+        }
         const results = await deliverOutboundPayloads({
           cfg,
           channel: outboundChannel,
@@ -147,14 +175,17 @@ export const sendHandlers: GatewayRequestHandlers = {
           payloads: [{ text: message, mediaUrl: request.mediaUrl, mediaUrls }],
           gifPlayback: request.gifPlayback,
           deps: outboundDeps,
-          mirror:
-            typeof request.sessionKey === "string" && request.sessionKey.trim()
+          mirror: providedSessionKey
+            ? {
+                sessionKey: providedSessionKey,
+                agentId: resolveSessionAgentId({ sessionKey: providedSessionKey, config: cfg }),
+                text: mirrorText || message,
+                mediaUrls: mirrorMediaUrls.length > 0 ? mirrorMediaUrls : undefined,
+              }
+            : derivedRoute
               ? {
-                  sessionKey: request.sessionKey.trim(),
-                  agentId: resolveSessionAgentId({
-                    sessionKey: request.sessionKey.trim(),
-                    config: cfg,
-                  }),
+                  sessionKey: derivedRoute.sessionKey,
+                  agentId: derivedAgentId,
                   text: mirrorText || message,
                   mediaUrls: mirrorMediaUrls.length > 0 ? mirrorMediaUrls : undefined,
                 }