chore(windows): instrument detached daemon launch

packages/cli/src/commands/daemon/local-daemon.ts

@@ -1,5 +1,5 @@
 import { spawn, spawnSync } from "node:child_process";
-import { existsSync, readFileSync } from "node:fs";
+import { appendFileSync, existsSync, readFileSync } from "node:fs";
 import { createRequire } from "node:module";
 import path from "node:path";
 import { loadConfig, resolvePaseoHome } from "@getpaseo/server";
@@ -64,6 +64,7 @@ const DETACHED_STARTUP_GRACE_MS = 1200;
 const PID_POLL_INTERVAL_MS = 100;
 const KILL_TIMEOUT_MS = 3000;
 const DAEMON_LOG_FILENAME = "daemon.log";
+const DAEMON_LAUNCH_LOG_FILENAME = "daemon-launch.log";
 const DAEMON_PID_FILENAME = "paseo.pid";
 
 export const DEFAULT_STOP_TIMEOUT_MS = 15_000;
@@ -114,6 +115,24 @@ function buildChildEnv(options: DaemonStartOptions): NodeJS.ProcessEnv {
   return childEnv;
 }
 
+function appendLaunchLog(home: string, message: string, details?: Record<string, unknown>): void {
+  const line = [
+    new Date().toISOString(),
+    "[CLI daemon]",
+    `pid=${process.pid}`,
+    message,
+    details ? JSON.stringify(details) : "",
+  ]
+    .filter((part) => part.length > 0)
+    .join(" ");
+
+  try {
+    appendFileSync(path.join(home, DAEMON_LAUNCH_LOG_FILENAME), `${line}\n`, "utf-8");
+  } catch {
+    // Keep launch debugging best-effort so daemon startup behavior is unchanged.
+  }
+}
+
 function resolveDaemonRunnerEntry(): string {
   const serverExportPath = require.resolve("@getpaseo/server");
   let currentDir = path.dirname(serverExportPath);
@@ -354,6 +373,14 @@ export async function startLocalDaemonDetached(
   const paseoHome = resolvePaseoHome(childEnv);
   const logPath = path.join(paseoHome, DAEMON_LOG_FILENAME);
   const daemonRunnerEntry = resolveDaemonRunnerEntry();
+  appendLaunchLog(paseoHome, "starting detached daemon", {
+    execPath: process.execPath,
+    execArgv: process.execArgv,
+    daemonRunnerEntry,
+    runnerArgs: buildRunnerArgs(options),
+    listen: childEnv.PASEO_LISTEN ?? null,
+    allowedHosts: childEnv.PASEO_ALLOWED_HOSTS ?? null,
+  });
   const child = spawn(
     process.execPath,
     [...process.execArgv, daemonRunnerEntry, ...buildRunnerArgs(options)],
@@ -364,6 +391,12 @@ export async function startLocalDaemonDetached(
     },
   );
 
+  appendLaunchLog(paseoHome, "detached spawn returned", {
+    childPid: child.pid ?? null,
+    spawnfile: child.spawnfile,
+    spawnargs: child.spawnargs,
+  });
+
   child.unref();
 
   const startup = await new Promise<DetachedStartupResult>((resolve) => {
@@ -378,16 +411,33 @@ export async function startLocalDaemonDetached(
     const timer = setTimeout(() => finish(startupReady()), DETACHED_STARTUP_GRACE_MS);
 
     child.once("error", (error) => {
+      appendLaunchLog(paseoHome, "detached child emitted error during grace period", {
+        childPid: child.pid ?? null,
+        message: error.message,
+      });
       clearTimeout(timer);
       finish(startupExited({ code: null, signal: null, error }));
     });
 
     child.once("exit", (code, signal) => {
+      appendLaunchLog(paseoHome, "detached child emitted exit during grace period", {
+        childPid: child.pid ?? null,
+        code,
+        signal,
+      });
       clearTimeout(timer);
       finish(startupExited({ code, signal }));
     });
   });
 
+  appendLaunchLog(paseoHome, "detached startup grace period completed", {
+    childPid: child.pid ?? null,
+    exitedEarly: startup.exitedEarly,
+    code: startup.exitedEarly ? startup.code : null,
+    signal: startup.exitedEarly ? startup.signal : null,
+    error: startup.exitedEarly ? startup.error?.message ?? null : null,
+  });
+
   if (startup.exitedEarly) {
     const reason = startup.error
       ? startup.error.message