Add pre-flight diagnostics for smart match to surface the actual error

Before spawning the Python script, the IPC handler now:
1. Logs Python path, script path, course dir, and dir existence
2. Runs a quick import check (numpy, fitz, sentence_transformers)
   and immediately returns a clear error if any are missing:
   "Python (/path) is missing packages: fitz. Reinstall ML environment."
3. On failure, shows full diagnostics in the terminal panel (not just
   a vague snackbar) with possible causes listed

This should reveal exactly why smart match fails on the user's machine.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: nodeeeeee

electron/main.js

@@ -997,7 +997,41 @@ function registerIpc() {
     const python = getPythonPath();
     const script = SCRIPTS.align;
     const outDir = getOutputDir();
-    console.log(`[align:suggestMatches] python=${python} script=${script} course=${cid} model=${model} outDir=${outDir}`);
+    const courseDir = path.join(outDir, String(cid));
+
+    // Pre-flight diagnostics
+    const diag = [];
+    diag.push(`Python: ${python} (exists: ${fs.existsSync(python)})`);
+    diag.push(`Script: ${script} (exists: ${fs.existsSync(script)})`);
+    diag.push(`DATA_DIR: ${DATA_DIR}`);
+    diag.push(`OutputDir: ${outDir}`);
+    diag.push(`CourseDir: ${courseDir} (exists: ${fs.existsSync(courseDir)})`);
+    diag.push(`Captions: ${fs.existsSync(path.join(courseDir, 'captions'))}`);
+    diag.push(`Materials: ${fs.existsSync(path.join(courseDir, 'materials'))}`);
+    console.log(`[align:suggestMatches] ${diag.join(' | ')}`);
+
+    // Quick pre-check: can this Python import the needed packages?
+    const checkCode = "import sys; " +
+      "errs=[]; " +
+      "[errs.append(n) for n in ['numpy','fitz','sentence_transformers'] if not __import__('importlib').util.find_spec(n)]; " +
+      "print('MISSING:'+','.join(errs) if errs else 'OK'); " +
+      "print('PYTHON:'+sys.executable); " +
+      "print('PREFIX:'+sys.prefix)";
+    const chk = spawnSync(python, ['-c', checkCode], {
+      encoding: 'utf8', timeout: 10000,
+      env: { ...process.env, AUTONOTE_DATA_DIR: DATA_DIR },
+    });
+    const chkOut = (chk.stdout || '') + (chk.stderr || '');
+    diag.push(`PreCheck: ${chkOut.replace(/\n/g, ' | ').trim()}`);
+    console.log(`[align:suggestMatches] precheck: ${chkOut.trim()}`);
+
+    if (chkOut.includes('MISSING:') && !chkOut.includes('MISSING:OK') && !chkOut.includes('MISSING:\n')) {
+      const missing = chkOut.match(/MISSING:(.+)/)?.[1]?.trim();
+      if (missing) {
+        resolve({ __error: `Python (${python}) is missing packages: ${missing}. Reinstall ML environment with these components enabled.` });
+        return;
+      }
+    }
 
     const cmd = [python, script, '--course', String(cid),
                  '--suggest-matches', '--match-model', model || 'bge-m3'];

electron/renderer/app.js

@@ -1503,14 +1503,22 @@ async function attachPageHandlers() {
       const matches = await window.api.alignSuggestMatches(cid, model);
 
       if (matches?.__error) {
-        snack(`Smart match failed: ${matches.__error}`, false);
-        if (statusEl) statusEl.textContent = 'Smart match failed — see error above.';
+        // Show error in both snackbar and terminal for full diagnostics
+        Term.write(`\n✗ Smart match error:\n${matches.__error}\n`, 'err');
+        snack(`Smart match failed — see terminal for details.`, false);
+        if (statusEl) statusEl.textContent = 'Smart match failed — see terminal below.';
         return;
       }
 
       if (!matches || !Object.keys(matches).length) {
-        snack('Embedding matching returned no results — using heuristic suggestions.', false);
-        if (statusEl) statusEl.textContent = 'No embedding matches found.';
+        Term.write('\n✗ Smart match returned empty results.\n'
+          + 'Possible causes:\n'
+          + '  - pymupdf not installed (cannot read PDF slide text)\n'
+          + '  - sentence-transformers not installed (cannot embed text)\n'
+          + '  - No captions or materials found for this course\n'
+          + `  - Course dir: check if files exist under Output Dir / ${cid}\n`, 'warn');
+        snack('No embedding matches — see terminal for diagnostics.', false);
+        if (statusEl) statusEl.textContent = 'No matches — check terminal.';
         return;
       }