refactor(routing): centralize inbound last-route policy

src/web/auto-reply/monitor/broadcast.ts

@@ -1,6 +1,6 @@
 import type { loadConfig } from "../../../config/config.js";
 import type { resolveAgentRoute } from "../../../routing/resolve-route.js";
-import { buildAgentSessionKey } from "../../../routing/resolve-route.js";
+import { buildAgentSessionKey, deriveLastRoutePolicy } from "../../../routing/resolve-route.js";
 import {
   buildAgentMainSessionKey,
   DEFAULT_MAIN_KEY,
@@ -70,6 +70,23 @@ export async function maybeBroadcastMessage(params: {
         agentId: normalizedAgentId,
         mainKey: DEFAULT_MAIN_KEY,
       }),
+      lastRoutePolicy: deriveLastRoutePolicy({
+        sessionKey: buildAgentSessionKey({
+          agentId: normalizedAgentId,
+          channel: "whatsapp",
+          accountId: params.route.accountId,
+          peer: {
+            kind: params.msg.chatType === "group" ? "group" : "direct",
+            id: params.peerId,
+          },
+          dmScope: params.cfg.session?.dmScope,
+          identityLinks: params.cfg.session?.identityLinks,
+        }),
+        mainSessionKey: buildAgentMainSessionKey({
+          agentId: normalizedAgentId,
+          mainKey: DEFAULT_MAIN_KEY,
+        }),
+      }),
     };
 
     try {

src/web/auto-reply/monitor/process-message.ts

@@ -19,7 +19,10 @@ import { recordSessionMetaFromInbound } from "../../../config/sessions.js";
 import { logVerbose, shouldLogVerbose } from "../../../globals.js";
 import type { getChildLogger } from "../../../logging.js";
 import { getAgentScopedMediaLocalRoots } from "../../../media/local-roots.js";
-import type { resolveAgentRoute } from "../../../routing/resolve-route.js";
+import {
+  resolveInboundLastRouteSessionKey,
+  type resolveAgentRoute,
+} from "../../../routing/resolve-route.js";
 import {
   readStoreAllowFromForDmPolicy,
   resolvePinnedMainDmOwnerFromAllowlist,
@@ -339,9 +342,13 @@ export async function processMessage(params: {
   });
   const shouldUpdateMainLastRoute =
     !pinnedMainDmRecipient || pinnedMainDmRecipient === dmRouteTarget;
+  const inboundLastRouteSessionKey = resolveInboundLastRouteSessionKey({
+    route: params.route,
+    sessionKey: params.route.sessionKey,
+  });
   if (
     dmRouteTarget &&
-    params.route.sessionKey === params.route.mainSessionKey &&
+    inboundLastRouteSessionKey === params.route.mainSessionKey &&
     shouldUpdateMainLastRoute
   ) {
     updateLastRouteInBackground({
@@ -357,7 +364,7 @@ export async function processMessage(params: {
     });
   } else if (
     dmRouteTarget &&
-    params.route.sessionKey === params.route.mainSessionKey &&
+    inboundLastRouteSessionKey === params.route.mainSessionKey &&
     pinnedMainDmRecipient
   ) {
     logVerbose(