fix: surface full sitespeed.io error output + robust binary resolution

- runner.js: auto-detects sitespeed.io via which/candidates instead of
  hardcoded path; collects all stderr and appends last 20 lines to the
  error so the real failure is visible in the UI log
- running.pug: render multi-line error messages line-by-line

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

runner.js

@@ -1,19 +1,46 @@
-import { spawn } from 'child_process';
+import { spawn, execSync } from 'child_process';
 import { join, dirname } from 'path';
 import { fileURLToPath } from 'url';
+import { existsSync } from 'fs';
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
 
-// Path to sitespeed.io — works both locally and in Docker
-const SITESPEED_BIN = process.env.SITESPEED_BIN ||
-  join(__dirname, '..', 'sitespeed.io', 'bin', 'sitespeed.js');
+// Resolve sitespeed.io binary.
+// In Docker the global install is on PATH; outside Docker use the local clone.
+function resolveBin() {
+  if (process.env.SITESPEED_BIN) return { cmd: 'node', scriptArg: process.env.SITESPEED_BIN };
+
+  // Try global install on PATH (works in Docker image)
+  try {
+    const globalPath = execSync('which sitespeed.io', { encoding: 'utf8' }).trim();
+    if (globalPath) return { cmd: globalPath, scriptArg: null };
+  } catch {}
+
+  // Try common global npm location
+  const candidates = [
+    '/usr/local/lib/node_modules/sitespeed.io/bin/sitespeed.js',
+    '/usr/lib/node_modules/sitespeed.io/bin/sitespeed.js',
+    join(__dirname, '..', 'sitespeed.io', 'bin', 'sitespeed.js'),
+  ];
+  for (const p of candidates) {
+    if (existsSync(p)) return { cmd: 'node', scriptArg: p };
+  }
+
+  throw new Error('sitespeed.io binary not found. Set SITESPEED_BIN env var.');
+}
 
 export function runTest(job, onLine) {
   return new Promise((resolve, reject) => {
     const outputFolder = join(__dirname, 'reports', job.id);
 
-    const args = [
-      SITESPEED_BIN,
+    let bin, scriptArg;
+    try {
+      ({ cmd: bin, scriptArg } = resolveBin());
+    } catch (err) {
+      return reject(err);
+    }
+
+    const sitespeedArgs = [
       job.url,
       '--browser', job.browser,
       '-n', String(job.runs),
@@ -24,46 +51,53 @@ export function runTest(job, onLine) {
       '--coach',
     ];
 
-    if (job.mobile) {
-      args.push('--mobile');
-    }
+    if (job.mobile) sitespeedArgs.push('--mobile');
 
-    // Chrome needs these flags when running inside Docker
+    // Chrome flags required in Docker
     if (process.env.IN_DOCKER) {
-      args.push('--browsertime.chrome.args', 'no-sandbox');
-      args.push('--browsertime.chrome.args', 'disable-dev-shm-usage');
-      // Disable GPU compositing — not needed in Xvfb and can cause crashes
-      args.push('--browsertime.chrome.args', 'disable-gpu');
+      sitespeedArgs.push('--browsertime.chrome.args', 'no-sandbox');
+      sitespeedArgs.push('--browsertime.chrome.args', 'disable-dev-shm-usage');
+      sitespeedArgs.push('--browsertime.chrome.args', 'disable-gpu');
     }
 
-    onLine(`[runner] Starting: node ${args.slice(0, 3).join(' ')} ...`);
-    onLine(`[runner] Output folder: ${outputFolder}`);
+    // Build the final argv for spawn
+    const spawnArgs = scriptArg
+      ? [scriptArg, ...sitespeedArgs]   // node /path/to/sitespeed.js <args>
+      : sitespeedArgs;                   // sitespeed.io <args>
 
-    const child = spawn('node', args, {
-      cwd: __dirname,
-      env: { ...process.env, DISPLAY: process.env.DISPLAY || ':99' },
-    });
+    const env = { ...process.env, DISPLAY: process.env.DISPLAY || ':99' };
+
+    onLine(`[runner] binary: ${bin}${scriptArg ? ' ' + scriptArg : ''}`);
+    onLine(`[runner] DISPLAY: ${env.DISPLAY}`);
+    onLine(`[runner] outputFolder: ${outputFolder}`);
+
+    const child = spawn(bin, spawnArgs, { cwd: __dirname, env });
+
+    // Collect all output lines — included in error if process fails
+    const allLines = [];
 
     child.stdout.on('data', (data) => {
       const lines = data.toString().split('\n').filter(Boolean);
-      for (const line of lines) onLine(line);
+      for (const line of lines) { allLines.push(line); onLine(line); }
     });
 
     child.stderr.on('data', (data) => {
       const lines = data.toString().split('\n').filter(Boolean);
-      for (const line of lines) onLine(`[stderr] ${line}`);
+      for (const line of lines) { allLines.push('[stderr] ' + line); onLine('[stderr] ' + line); }
     });
 
     child.on('close', (code) => {
       if (code === 0) {
         resolve(outputFolder);
       } else {
-        reject(new Error(`sitespeed.io exited with code ${code}`));
+        // Surface the last 20 lines of output so the error is visible in the UI
+        const tail = allLines.slice(-20).join('\n');
+        reject(new Error(`sitespeed.io exited with code ${code}\n${tail}`));
       }
     });
 
     child.on('error', (err) => {
-      reject(new Error(`Failed to spawn sitespeed.io: ${err.message}`));
+      reject(new Error(`Failed to spawn sitespeed.io (${bin}): ${err.message}`));
     });
   });
 }

views/running.pug

@@ -65,9 +65,14 @@ block content
       badge.className = 'text-xs px-3 py-1 rounded-full bg-red-100 text-red-800 font-semibold';
       try {
         const d = JSON.parse(e.data);
+        // Render each line of the error message separately so multi-line errors are readable
+        const lines = d.message.split('\n');
+        for (const line of lines) {
           const el = document.createElement('div');
           el.className = 'text-red-400 log-line';
-        el.textContent = '[ERROR] ' + d.message;
+          el.textContent = line;
           logBox.appendChild(el);
+        }
+        logBox.scrollTop = logBox.scrollHeight;
       } catch {}
     });