feat(debug): add debug_compile function for PDF test + new tab preview

app.py

@@ -491,6 +491,53 @@ def _ensure_left_logo_or_disable(OUTPUT_DIR: Path, logs):
         logs.append(f"⚠️ Failed left_logo fallback: {e}")
     return False
 
+def debug_compile():
+    """Generate a minimal LaTeX file, compile it to PDF, and return an HTML preview with an 'open in new tab' link."""
+    logs = [f"🐞 Debug start at {_now_str()}"]
+    # Prepare workspace
+    run_id, WORK_DIR, LOG_PATH, _ = _prepare_workspace(logs)
+    dbg_dir = WORK_DIR / "debug"
+    dbg_dir.mkdir(parents=True, exist_ok=True)
+    tex_path = dbg_dir / "test.tex"
+    tex_path.write_text(r"""
+\documentclass{article}
+\usepackage[T1]{fontenc}
+\usepackage{lmodern}
+\usepackage[margin=1in]{geometry}
+\begin{document}
+Hello, PDF!\\
+This is a debug build generated at \today.
+\end{document}
+""".strip(), encoding="utf-8")
+
+    logs.append(f"Workspace: runs/{WORK_DIR.name}")
+    logs.append(f"Writing: debug/test.tex")
+
+    pdf_path = _compile_tex_to_pdf(tex_path, logs)
+    if not pdf_path or not pdf_path.exists():
+        logs.append("❌ Failed to compile debug PDF.")
+        _write_logs(LOG_PATH, logs)
+        return (
+            "<div style='color:#b00'><b>Debug PDF compile failed.</b></div>"
+            + f"<pre style='white-space:pre-wrap;background:#f7f7f8;padding:8px;border-radius:6px'>{'\n'.join(logs)}</pre>"
+        )
+
+    # Build preview + open-new-tab link
+    try:
+        b64 = base64.b64encode(pdf_path.read_bytes()).decode("utf-8")
+        open_tab = f"<a target='_blank' rel='noopener' href='data:application/pdf;base64,{b64}'>Open PDF in new tab</a>"
+        html = (
+            f"<div style='margin-bottom:8px'>{open_tab}</div>"
+            + _pdf_to_iframe_html(pdf_path, height="700px")
+            + f"<pre style='white-space:pre-wrap;background:#f7f7f8;padding:8px;border-radius:6px;margin-top:8px'>{'\n'.join(logs[-60:])}</pre>"
+        )
+        _write_logs(LOG_PATH, logs)
+        return html
+    except Exception as e:
+        logs.append(f"⚠️ Building preview failed: {e}")
+        _write_logs(LOG_PATH, logs)
+        return f"<div>Compiled but preview failed: {e}</div>"
+
 # =====================
 # Gradio pipeline function (ISOLATED)
 # =====================