feat(stats): add v1 immersion stats dashboard (#19)

src/main/runtime/stats-daemon.ts

@@ -0,0 +1,72 @@
+import fs from 'node:fs';
+import path from 'node:path';
+
+export type BackgroundStatsServerState = {
+  pid: number;
+  port: number;
+  startedAtMs: number;
+};
+
+export function readBackgroundStatsServerState(
+  statePath: string,
+): BackgroundStatsServerState | null {
+  try {
+    const raw = JSON.parse(
+      fs.readFileSync(statePath, 'utf8'),
+    ) as Partial<BackgroundStatsServerState>;
+    const pid = raw.pid;
+    const port = raw.port;
+    const startedAtMs = raw.startedAtMs;
+    if (
+      typeof pid !== 'number' ||
+      !Number.isInteger(pid) ||
+      pid <= 0 ||
+      typeof port !== 'number' ||
+      !Number.isInteger(port) ||
+      port <= 0 ||
+      typeof startedAtMs !== 'number' ||
+      !Number.isInteger(startedAtMs) ||
+      startedAtMs <= 0
+    ) {
+      return null;
+    }
+    return {
+      pid,
+      port,
+      startedAtMs,
+    };
+  } catch {
+    return null;
+  }
+}
+
+export function writeBackgroundStatsServerState(
+  statePath: string,
+  state: BackgroundStatsServerState,
+): void {
+  fs.mkdirSync(path.dirname(statePath), { recursive: true });
+  fs.writeFileSync(statePath, JSON.stringify(state, null, 2), 'utf8');
+}
+
+export function removeBackgroundStatsServerState(statePath: string): void {
+  try {
+    fs.rmSync(statePath, { force: true });
+  } catch {
+    // ignore
+  }
+}
+
+export function isBackgroundStatsServerProcessAlive(pid: number): boolean {
+  try {
+    process.kill(pid, 0);
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+export function resolveBackgroundStatsServerUrl(
+  state: Pick<BackgroundStatsServerState, 'port'>,
+): string {
+  return `http://127.0.0.1:${state.port}`;
+}