improve(qmd-brain): avoid shell execution in embed trigger

skills/qmd-brain/handler.ts

@@ -7,10 +7,10 @@
  *   - embed_to_pg.py (Python venv at /home/selig/apps/qmd-pg/)
  */
 
-import { exec, execFile } from 'child_process';
+import { spawn, execFile } from 'child_process';
 import { promisify } from 'util';
+import { openSync, closeSync } from 'fs';
 
-const execAsync = promisify(exec);
 const execFileAsync = promisify(execFile);
 
 const QMD_CMD = '/home/selig/.nvm/versions/node/v24.13.1/bin/qmd';
@@ -66,12 +66,28 @@ function formatPgResults(results: SearchResult[]): string {
 
 /** 觸發向量索引更新 */
 async function triggerEmbed(): Promise<string> {
+  const env = { ...process.env, HOME: '/home/selig' };
+  const logPath = '/tmp/qmd-embed.log';
+
   try {
-    // 背景執行，不等待完成
-    exec(
-      `${QMD_CMD} embed 2>&1 >> /tmp/qmd-embed.log & ${EMBED_PY_BIN} ${EMBED_PY_SCRIPT} embed 2>&1 >> /tmp/qmd-embed.log &`,
-      { env: { ...process.env, HOME: '/home/selig' } }
-    );
+    const fdQmd = openSync(logPath, 'a');
+    const qmdProc = spawn(QMD_CMD, ['embed'], {
+      env,
+      detached: true,
+      stdio: ['ignore', fdQmd, fdQmd],
+    });
+    qmdProc.unref();
+    closeSync(fdQmd);
+
+    const fdPg = openSync(logPath, 'a');
+    const pgProc = spawn(EMBED_PY_BIN, [EMBED_PY_SCRIPT, 'embed'], {
+      env,
+      detached: true,
+      stdio: ['ignore', fdPg, fdPg],
+    });
+    pgProc.unref();
+    closeSync(fdPg);
+
     return '✅ 索引更新已在背景啟動，約需 1-5 分鐘完成。';
   } catch (e: any) {
     return `❌ 索引啟動失敗: ${e.message}`;