fix: preserve session thread ids in chat session snapshots

src/gateway/server-chat.agent-events.test.ts

@@ -764,6 +764,7 @@ describe("agent event handler", () => {
       totalTokensFresh: true,
       contextTokens: 21,
       estimatedCostUsd: 0.12,
+      lastThreadId: 42,
       status: "running",
       startedAt: 900,
       runtimeMs: 750,
@@ -805,6 +806,7 @@ describe("agent event handler", () => {
         totalTokensFresh: true,
         contextTokens: 21,
         estimatedCostUsd: 0.12,
+        lastThreadId: 42,
       }),
       new Set(["conn-session"]),
       { dropIfSlow: true },

src/gateway/server-chat.ts

@@ -511,6 +511,7 @@ export function createAgentEventHandler({
       lastChannel: row?.lastChannel,
       lastTo: row?.lastTo,
       lastAccountId: row?.lastAccountId,
+      lastThreadId: row?.lastThreadId,
       totalTokens: row?.totalTokens,
       totalTokensFresh: row?.totalTokensFresh,
       contextTokens: row?.contextTokens,

src/gateway/session-utils.ts

@@ -1234,6 +1234,7 @@ export function buildGatewaySessionRow(params: {
     lastChannel: deliveryFields.lastChannel ?? entry?.lastChannel,
     lastTo: deliveryFields.lastTo ?? entry?.lastTo,
     lastAccountId: deliveryFields.lastAccountId ?? entry?.lastAccountId,
+    lastThreadId: deliveryFields.lastThreadId ?? entry?.lastThreadId,
   };
 }
 

src/gateway/session-utils.types.ts

@@ -58,6 +58,7 @@ export type GatewaySessionRow = {
   lastChannel?: SessionEntry["lastChannel"];
   lastTo?: string;
   lastAccountId?: string;
+  lastThreadId?: SessionEntry["lastThreadId"];
 };
 
 export type GatewayAgentRow = SharedGatewayAgentRow;