Summary

• Fixes [Bug]: [Regression] post-attach.update-sentinel ~9s sync block per model_call (previously 0ms) — v2026.5.7 #79264 by moving restart-sentinel state-dir and sentinel-file probes off synchronous fs.existsSync during gateway post-attach startup.
• Keeps the existing restart-sentinel refresh/wake behavior, including OPENCLAW_HOME, OPENCLAW_STATE_DIR, and legacy .clawdbot fallback handling.
• Adds a regression test that fails if the restart-sentinel presence check uses sync filesystem probes on the state path.

Real behavior proof

• Behavior or issue addressed: gateway post-attach restart-sentinel presence checks no longer synchronously probe the configured state directory, so slow Windows or redirected state dirs cannot block the event loop on this path.
• Real environment tested: local OpenClaw checkout on macOS, Node 26.0.0, with a real temporary OPENCLAW_STATE_DIR containing restart-sentinel.json.
• Exact steps or command run after this patch: ran a live node --import tsx command that monkey-patched fs.existsSync to throw for the configured state path, imported the gateway startup module, and called the restart-sentinel presence check against the real temp state directory.
• Evidence after fix:

$ OPENCLAW_STATE_DIR="$tmp" node --import tsx --input-type=module - <<'EOF'
import fs from "node:fs";
const actualExistsSync = fs.existsSync;
fs.existsSync = (candidate) => {
  if (String(candidate).startsWith(process.env.OPENCLAW_STATE_DIR ?? "")) {
    throw new Error("sync restart-sentinel state probe used");
  }
  return actualExistsSync(candidate);
};
const { __testing } = await import("./src/gateway/server-startup-post-attach.ts");
const present = await __testing.hasRestartSentinelFileFast({
  OPENCLAW_STATE_DIR: process.env.OPENCLAW_STATE_DIR,
});
console.log(JSON.stringify({ restartSentinelPresent: present, syncStateProbe: "not called" }));
EOF
{"restartSentinelPresent":true,"syncStateProbe":"not called"}

• Observed result after fix: the real temp restart sentinel was detected and the injected synchronous state-path probe trap was not hit.
• What was not tested: Windows redirected-home latency was not reproduced directly; this proof verifies the blocking sync filesystem call is gone from the implicated startup path.

Verification

• pnpm test src/gateway/server-startup-post-attach.test.ts
• env -u OPENCLAW_TESTBOX -u OPENCLAW_TESTBOX_REMOTE_RUN -u OPENCLAW_TESTBOX_ID pnpm check:changed
• git diff --check origin/main...HEAD