Fix text exporter

app/scripts/export-txt.mjs

@@ -35,16 +35,23 @@ async function run(command, args = [], options = {}) {
   });
 }
 
-async function waitForServer(url, timeoutMs = 60000) {
+async function waitForServer(urlOrFn, timeoutMs = 60000) {
+  const getUrl = typeof urlOrFn === 'function' ? urlOrFn : () => urlOrFn;
   const start = Date.now();
   while (Date.now() - start < timeoutMs) {
     try {
+      const url = getUrl();
+      if (!url) {
+        await delay(200);
+        continue;
+      }
       const res = await fetch(url);
       if (res.ok) return;
     } catch { }
     await delay(500);
   }
-  throw new Error(`Server did not start in time: ${url}`);
+  const lastUrl = getUrl();
+  throw new Error(`Server did not start in time: ${lastUrl || '(unknown url)'}`);
 }
 
 function parseArgs(argv) {
@@ -418,6 +425,22 @@ async function main() {
   console.log('> Starting Astro preview…');
   // Capture stdout to detect the actual port used
   let capturedPort = 8080;
+  let sawPreviewUrl = false;
+
+  const maybeCapturePort = (output) => {
+    const match = output.match(/http:\/\/localhost:(\d+)\//);
+    if (match) {
+      capturedPort = parseInt(match[1]);
+      sawPreviewUrl = true;
+    }
+  };
+
+  const previewPortEnv = process.env.PREVIEW_PORT ? Number(process.env.PREVIEW_PORT) : null;
+  if (previewPortEnv) {
+    capturedPort = previewPortEnv;
+    sawPreviewUrl = true;
+  }
+
   const preview = spawn('npm', ['run', 'preview'], { 
     cwd, 
     stdio: ['ignore', 'pipe', 'pipe'],
@@ -428,27 +451,28 @@ async function main() {
   preview.stdout.on('data', (data) => {
     const output = data.toString();
     process.stdout.write(output);
-    const match = output.match(/http:\/\/localhost:(\d+)/);
-    if (match) {
-      capturedPort = parseInt(match[1]);
-    }
+    maybeCapturePort(output);
   });
   
   preview.stderr.on('data', (data) => {
-    process.stderr.write(data);
+    const output = data.toString();
+    process.stderr.write(output);
+    maybeCapturePort(output);
   });
   
   const previewExit = new Promise((resolvePreview) => {
     preview.on('close', (code, signal) => resolvePreview({ code, signal }));
   });
   
-  // Wait a bit for the server to start and output the port
-  await delay(3000);
-  const baseUrl = `http://localhost:${capturedPort}/`;
+  const getBaseUrl = () => {
+    if (!sawPreviewUrl) return null;
+    return `http://localhost:${capturedPort}/`;
+  };
   
   try {
-    await waitForServer(baseUrl, 60000);
-    console.log('> Server ready, extracting content…');
+    await waitForServer(getBaseUrl, 60000);
+    const baseUrl = getBaseUrl();
+    console.log(`> Server ready (${baseUrl}), extracting content…`);
     
     const browser = await chromium.launch({ headless: true });
     try {