refactor(infra): extract json file + async lock helpers

src/infra/json-files.ts

@@ -0,0 +1,52 @@
+import { randomUUID } from "node:crypto";
+import fs from "node:fs/promises";
+import path from "node:path";
+
+export async function readJsonFile<T>(filePath: string): Promise<T | null> {
+  try {
+    const raw = await fs.readFile(filePath, "utf8");
+    return JSON.parse(raw) as T;
+  } catch {
+    return null;
+  }
+}
+
+export async function writeJsonAtomic(
+  filePath: string,
+  value: unknown,
+  options?: { mode?: number },
+) {
+  const mode = options?.mode ?? 0o600;
+  const dir = path.dirname(filePath);
+  await fs.mkdir(dir, { recursive: true });
+  const tmp = `${filePath}.${randomUUID()}.tmp`;
+  await fs.writeFile(tmp, JSON.stringify(value, null, 2), "utf8");
+  try {
+    await fs.chmod(tmp, mode);
+  } catch {
+    // best-effort; ignore on platforms without chmod
+  }
+  await fs.rename(tmp, filePath);
+  try {
+    await fs.chmod(filePath, mode);
+  } catch {
+    // best-effort; ignore on platforms without chmod
+  }
+}
+
+export function createAsyncLock() {
+  let lock: Promise<void> = Promise.resolve();
+  return async function withLock<T>(fn: () => Promise<T>): Promise<T> {
+    const prev = lock;
+    let release: (() => void) | undefined;
+    lock = new Promise<void>((resolve) => {
+      release = resolve;
+    });
+    await prev;
+    try {
+      return await fn();
+    } finally {
+      release?.();
+    }
+  };
+}

src/infra/pairing-files.ts

@@ -1,8 +1,8 @@
-import { randomUUID } from "node:crypto";
-import fs from "node:fs/promises";
 import path from "node:path";
 import { resolveStateDir } from "../config/paths.js";
 
+export { createAsyncLock, readJsonFile, writeJsonAtomic } from "./json-files.js";
+
 export function resolvePairingPaths(baseDir: string | undefined, subdir: string) {
   const root = baseDir ?? resolveStateDir();
   const dir = path.join(root, subdir);
@@ -13,33 +13,6 @@ export function resolvePairingPaths(baseDir: string | undefined, subdir: string)
   };
 }
 
-export async function readJsonFile<T>(filePath: string): Promise<T | null> {
-  try {
-    const raw = await fs.readFile(filePath, "utf8");
-    return JSON.parse(raw) as T;
-  } catch {
-    return null;
-  }
-}
-
-export async function writeJsonAtomic(filePath: string, value: unknown) {
-  const dir = path.dirname(filePath);
-  await fs.mkdir(dir, { recursive: true });
-  const tmp = `${filePath}.${randomUUID()}.tmp`;
-  await fs.writeFile(tmp, JSON.stringify(value, null, 2), "utf8");
-  try {
-    await fs.chmod(tmp, 0o600);
-  } catch {
-    // best-effort; ignore on platforms without chmod
-  }
-  await fs.rename(tmp, filePath);
-  try {
-    await fs.chmod(filePath, 0o600);
-  } catch {
-    // best-effort; ignore on platforms without chmod
-  }
-}
-
 export function pruneExpiredPending<T extends { ts: number }>(
   pendingById: Record<string, T>,
   nowMs: number,
@@ -51,20 +24,3 @@ export function pruneExpiredPending<T extends { ts: number }>(
     }
   }
 }
-
-export function createAsyncLock() {
-  let lock: Promise<void> = Promise.resolve();
-  return async function withLock<T>(fn: () => Promise<T>): Promise<T> {
-    const prev = lock;
-    let release: (() => void) | undefined;
-    lock = new Promise<void>((resolve) => {
-      release = resolve;
-    });
-    await prev;
-    try {
-      return await fn();
-    } finally {
-      release?.();
-    }
-  };
-}

src/infra/voicewake.ts

@@ -1,7 +1,6 @@
-import { randomUUID } from "node:crypto";
-import fs from "node:fs/promises";
 import path from "node:path";
 import { resolveStateDir } from "../config/paths.js";
+import { createAsyncLock, readJsonFile, writeJsonAtomic } from "./json-files.js";
 
 export type VoiceWakeConfig = {
   triggers: string[];
@@ -22,37 +21,7 @@ function sanitizeTriggers(triggers: string[] | undefined | null): string[] {
   return cleaned.length > 0 ? cleaned : DEFAULT_TRIGGERS;
 }
 
-async function readJSON<T>(filePath: string): Promise<T | null> {
+const withLock = createAsyncLock();
-  try {
-    const raw = await fs.readFile(filePath, "utf8");
-    return JSON.parse(raw) as T;
-  } catch {
-    return null;
-  }
-}
-
-async function writeJSONAtomic(filePath: string, value: unknown) {
-  const dir = path.dirname(filePath);
-  await fs.mkdir(dir, { recursive: true });
-  const tmp = `${filePath}.${randomUUID()}.tmp`;
-  await fs.writeFile(tmp, JSON.stringify(value, null, 2), "utf8");
-  await fs.rename(tmp, filePath);
-}
-
-let lock: Promise<void> = Promise.resolve();
-async function withLock<T>(fn: () => Promise<T>): Promise<T> {
-  const prev = lock;
-  let release: (() => void) | undefined;
-  lock = new Promise<void>((resolve) => {
-    release = resolve;
-  });
-  await prev;
-  try {
-    return await fn();
-  } finally {
-    release?.();
-  }
-}
 
 export function defaultVoiceWakeTriggers() {
   return [...DEFAULT_TRIGGERS];
@@ -60,7 +29,7 @@ export function defaultVoiceWakeTriggers() {
 
 export async function loadVoiceWakeConfig(baseDir?: string): Promise<VoiceWakeConfig> {
   const filePath = resolvePath(baseDir);
-  const existing = await readJSON<VoiceWakeConfig>(filePath);
+  const existing = await readJsonFile<VoiceWakeConfig>(filePath);
   if (!existing) {
     return { triggers: defaultVoiceWakeTriggers(), updatedAtMs: 0 };
   }
@@ -84,7 +53,7 @@ export async function setVoiceWakeTriggers(
       triggers: sanitized,
       updatedAtMs: Date.now(),
     };
-    await writeJSONAtomic(filePath, next);
+    await writeJsonAtomic(filePath, next);
     return next;
   });
 }