fix(gateway): detect launchd supervision via XPC_SERVICE_NAME

On macOS, launchd sets XPC_SERVICE_NAME on managed processes but does
not set LAUNCH_JOB_LABEL or LAUNCH_JOB_NAME. Without checking
XPC_SERVICE_NAME, isLikelySupervisedProcess() returns false for
launchd-managed gateways, causing restartGatewayProcessWithFreshPid()
to fork a detached child instead of returning "supervised". The
detached child holds the gateway lock while launchd simultaneously
respawns the original process (KeepAlive=true), leading to an infinite
lock-timeout / restart loop.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/infra/process-respawn.test.ts

@@ -108,6 +108,16 @@ describe("restartGatewayProcessWithFreshPid", () => {
     expect(spawnMock).not.toHaveBeenCalled();
   });
 
+  it("returns supervised when XPC_SERVICE_NAME is set by launchd", () => {
+    clearSupervisorHints();
+    setPlatform("darwin");
+    process.env.XPC_SERVICE_NAME = "ai.openclaw.gateway";
+    const result = restartGatewayProcessWithFreshPid();
+    expect(result.mode).toBe("supervised");
+    expect(triggerOpenClawRestartMock).not.toHaveBeenCalled();
+    expect(spawnMock).not.toHaveBeenCalled();
+  });
+
   it("spawns detached child with current exec argv", () => {
     delete process.env.OPENCLAW_NO_RESPAWN;
     clearSupervisorHints();

src/infra/supervisor-markers.ts

@@ -1,6 +1,7 @@
 const LAUNCHD_SUPERVISOR_HINT_ENV_VARS = [
   "LAUNCH_JOB_LABEL",
   "LAUNCH_JOB_NAME",
+  "XPC_SERVICE_NAME",
   "OPENCLAW_LAUNCHD_LABEL",
 ] as const;