diff --git a/src/config/sessions.ts b/src/config/sessions.ts
index 922df7461..d94e10dd1 100644
--- a/src/config/sessions.ts
+++ b/src/config/sessions.ts
@@ -133,6 +133,17 @@ export type SessionEntry = {
   skillsSnapshot?: SessionSkillSnapshot;
 };
 
+export function mergeSessionEntry(
+  existing: SessionEntry | undefined,
+  patch: Partial<SessionEntry>,
+): SessionEntry {
+  const sessionId =
+    patch.sessionId ?? existing?.sessionId ?? crypto.randomUUID();
+  const updatedAt = patch.updatedAt ?? existing?.updatedAt ?? Date.now();
+  if (!existing) return { ...patch, sessionId, updatedAt };
+  return { ...existing, ...patch, sessionId, updatedAt };
+}
+
 export type GroupKeyResolution = {
   key: string;
   legacyKey?: string;
@@ -487,17 +498,14 @@ export async function updateLastRoute(params: {
   const store = loadSessionStore(storePath);
   const existing = store[sessionKey];
   const now = Date.now();
-  const sessionId = existing?.sessionId ?? crypto.randomUUID();
-  const next: SessionEntry = {
-    ...(existing ?? { sessionId, updatedAt: 0 }),
-    sessionId,
+  const next = mergeSessionEntry(existing, {
     updatedAt: Math.max(existing?.updatedAt ?? 0, now),
     lastProvider: provider,
     lastTo: to?.trim() ? to.trim() : undefined,
     lastAccountId: accountId?.trim()
       ? accountId.trim()
       : existing?.lastAccountId,
-  };
+  });
   store[sessionKey] = next;
   await saveSessionStore(storePath, store);
   return next;
diff --git a/src/gateway/server-bridge.ts b/src/gateway/server-bridge.ts
index bd1753362..56ac4bf55 100644
--- a/src/gateway/server-bridge.ts
+++ b/src/gateway/server-bridge.ts
@@ -23,6 +23,7 @@ import {
 import { buildConfigSchema } from "../config/schema.js";
 import {
   loadSessionStore,
+  mergeSessionEntry,
   resolveMainSessionKeyFromConfig,
   type SessionEntry,
   saveSessionStore,
@@ -810,16 +811,10 @@ export function createBridgeHandlers(ctx: BridgeHandlersContext) {
           });
           const now = Date.now();
           const sessionId = entry?.sessionId ?? randomUUID();
-          const sessionEntry: SessionEntry = {
+          const sessionEntry = mergeSessionEntry(entry, {
             sessionId,
             updatedAt: now,
-            thinkingLevel: entry?.thinkingLevel,
-            verboseLevel: entry?.verboseLevel,
-            reasoningLevel: entry?.reasoningLevel,
-            systemSent: entry?.systemSent,
-            lastProvider: entry?.lastProvider,
-            lastTo: entry?.lastTo,
-          };
+          });
           const clientRunId = p.idempotencyKey;
           registerAgentRunContext(clientRunId, { sessionKey: p.sessionKey });
 
diff --git a/src/gateway/server-methods/chat.ts b/src/gateway/server-methods/chat.ts
index 1dca7c8f1..f0f36cbaf 100644
--- a/src/gateway/server-methods/chat.ts
+++ b/src/gateway/server-methods/chat.ts
@@ -3,7 +3,7 @@ import { randomUUID } from "node:crypto";
 import { resolveThinkingDefault } from "../../agents/model-selection.js";
 import { resolveAgentTimeoutMs } from "../../agents/timeout.js";
 import { agentCommand } from "../../commands/agent.js";
-import { type SessionEntry, saveSessionStore } from "../../config/sessions.js";
+import { mergeSessionEntry, saveSessionStore } from "../../config/sessions.js";
 import { registerAgentRunContext } from "../../infra/agent-events.js";
 import { defaultRuntime } from "../../runtime.js";
 import { resolveSendPolicy } from "../../sessions/send-policy.js";
@@ -197,17 +197,10 @@ export const chatHandlers: GatewayRequestHandlers = {
     });
     const now = Date.now();
     const sessionId = entry?.sessionId ?? randomUUID();
-    const sessionEntry: SessionEntry = {
+    const sessionEntry = mergeSessionEntry(entry, {
       sessionId,
       updatedAt: now,
-      thinkingLevel: entry?.thinkingLevel,
-      verboseLevel: entry?.verboseLevel,
-      reasoningLevel: entry?.reasoningLevel,
-      systemSent: entry?.systemSent,
-      sendPolicy: entry?.sendPolicy,
-      lastProvider: entry?.lastProvider,
-      lastTo: entry?.lastTo,
-    };
+    });
     const clientRunId = p.idempotencyKey;
     registerAgentRunContext(clientRunId, { sessionKey: p.sessionKey });