diff --git a/src/infra/heartbeat-runner.ts b/src/infra/heartbeat-runner.ts
index 1fa7065bc..f75e37fef 100644
--- a/src/infra/heartbeat-runner.ts
+++ b/src/infra/heartbeat-runner.ts
@@ -12,6 +12,7 @@ import type { ClawdbotConfig } from "../config/config.js";
 import { loadConfig } from "../config/config.js";
 import {
   loadSessionStore,
+  resolveMainSessionKey,
   resolveStorePath,
   type SessionEntry,
   saveSessionStore,
@@ -113,8 +114,8 @@ function resolveHeartbeatAckMaxChars(cfg: ClawdbotConfig) {
 function resolveHeartbeatSession(cfg: ClawdbotConfig) {
   const sessionCfg = cfg.session;
   const scope = sessionCfg?.scope ?? "per-sender";
-  const mainKey = (sessionCfg?.mainKey ?? "main").trim() || "main";
-  const sessionKey = scope === "global" ? "global" : mainKey;
+  const sessionKey =
+    scope === "global" ? "global" : resolveMainSessionKey(cfg);
   const storePath = resolveStorePath(sessionCfg?.store);
   const store = loadSessionStore(storePath);
   const entry = store[sessionKey];