Debug: add image preview (first page) with PyMuPDF/pdfium; return PDF path from debug flows; chain .then to render image

app.py

@@ -3673,17 +3673,17 @@ def debug_compile_last_pipeline_zip():
             + _pdf_to_iframe_html(pdf_path, height="700px")
         )
         _write_logs(LOG_PATH, logs)
-        return html
+        return html, str(pdf_path)
     except Exception as e:
         logs.append(f"⚠️ preview failed: {e}")
         _write_logs(LOG_PATH, logs)
-        return f"<div>Compiled but preview failed: {e}</div>"
+        return f"<div>Compiled but preview failed: {e}</div>", None
 
 def debug_compile_uploaded_zip(zip_file):
-    """Compile an uploaded poster zip (user-provided) and preview PDF."""
+    """Compile an uploaded poster zip (user-provided); return preview HTML + PDF path."""
     logs = [f"🐞 Debug(upload) at {_now_str()}"]
     if not zip_file:
-        return "<div style='color:#b00'>Please upload a .zip file first.</div>"
+        return "<div style='color:#b00'>Please upload a .zip file first.</div>", None
     # Prepare workspace
     run_id, WORK_DIR, LOG_PATH, _ = _prepare_workspace(logs)
     work_zip_dir = WORK_DIR / "zip_upload"
@@ -3695,7 +3695,7 @@ def debug_compile_uploaded_zip(zip_file):
     except Exception as e:
         logs.append(f"❌ save upload failed: {e}")
         _write_logs(LOG_PATH, logs)
-        return "<div style='color:#b00'>Save upload failed.</div>"
+        return "<div style='color:#b00'>Save upload failed.</div>", None
     # Extract
     try:
         import zipfile as _zf
@@ -3704,7 +3704,7 @@ def debug_compile_uploaded_zip(zip_file):
     except Exception as e:
         logs.append(f"❌ unzip failed: {e}")
         _write_logs(LOG_PATH, logs)
-        return "<div style='color:#b00'>Unzip failed.</div>"
+        return "<div style='color:#b00'>Unzip failed.</div>", None
     # Find tex
     tex_path = None
     for name in ("poster_output.tex", "poster.tex"):
@@ -3748,7 +3748,8 @@ def debug_compile_uploaded_zip(zip_file):
             "<div style='color:#b00'><b>Compile failed.</b></div>"
             + "<pre style='white-space:pre-wrap;background:#f7f7f8;padding:8px;border-radius:6px'>"
             + "\n".join(logs)
-            + "</pre>"
+            + "</pre>",
+            None,
         )
     try:
         b64 = base64.b64encode(pdf_path.read_bytes()).decode("utf-8")