Fix Streamlit app: use radio buttons instead of tabs for input selection

- Replace tabs with radio buttons for input type selection (more reliable)
- Fix page_icon to use emoji instead of file path
- Add proper session state initialization
- Ensure variables are correctly scoped

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app.py

@@ -571,7 +571,7 @@ def create_distribution_chart(result_df, categories):
 # Page config
 st.set_page_config(
     page_title="CatLLM - Research Data Classifier",
-    page_icon="logo.png",
+    page_icon="🐱",
     layout="wide"
 )
 
@@ -586,6 +586,14 @@ if 'extracted_categories' not in st.session_state:
     st.session_state.extracted_categories = None
 if 'results' not in st.session_state:
     st.session_state.results = None
+if 'active_tab' not in st.session_state:
+    st.session_state.active_tab = "survey"
+if 'survey_data' not in st.session_state:
+    st.session_state.survey_data = None
+if 'pdf_data' not in st.session_state:
+    st.session_state.pdf_data = None
+if 'image_data' not in st.session_state:
+    st.session_state.image_data = None
 
 # Logo and title
 col_logo, col_title = st.columns([1, 6])
@@ -630,24 +638,33 @@ Soria, C. (2025). CatLLM: A Python package for LLM-based text classification. DO
 col_input, col_output = st.columns([1, 1])
 
 with col_input:
-    # Input type tabs
-    tab_survey, tab_pdf, tab_images = st.tabs(["Survey Responses", "PDF Documents", "Images"])
+    # Input type selector
+    input_type_choice = st.radio(
+        "Input Type",
+        options=["Survey Responses", "PDF Documents", "Images"],
+        horizontal=True,
+        key="input_type_radio"
+    )
+
+    # Initialize variables
+    input_data = None
+    input_type_selected = "text"
+    description = ""
+    original_filename = "data"
+    pdf_mode = "Image (visual documents)"
+
+    if input_type_choice == "Survey Responses":
+        input_type_selected = "text"
 
-    with tab_survey:
         uploaded_file = st.file_uploader(
             "Upload Data (CSV or Excel)",
             type=['csv', 'xlsx', 'xls'],
             key="survey_file"
         )
 
-        # Load example button
         if st.button("Try Example Dataset", key="example_btn"):
-            try:
-                st.session_state.example_loaded = True
-            except:
-                st.error("Could not load example dataset")
+            st.session_state.example_loaded = True
 
-        # Column selector
         columns = []
         df = None
         if uploaded_file is not None:
@@ -675,15 +692,15 @@ with col_input:
             key="survey_column"
         )
 
-        input_type_selected = "text"
-        input_data = None
         description = selected_column if columns else ""
         original_filename = uploaded_file.name if uploaded_file else "example_data.csv"
 
         if df is not None and columns and selected_column in columns:
             input_data = df[selected_column].tolist()
 
-    with tab_pdf:
+    elif input_type_choice == "PDF Documents":
+        input_type_selected = "pdf"
+
         pdf_files = st.file_uploader(
             "Upload PDF Document(s)",
             type=['pdf'],
@@ -704,11 +721,9 @@ with col_input:
             key="pdf_mode"
         )
 
-        input_type_selected = "pdf"
         if pdf_files:
             input_data = []
             for f in pdf_files:
-                # Save to temp file
                 with tempfile.NamedTemporaryFile(delete=False, suffix='.pdf') as tmp:
                     tmp.write(f.read())
                     input_data.append(tmp.name)
@@ -716,7 +731,9 @@ with col_input:
             original_filename = "pdf_files"
             st.success(f"Uploaded {len(pdf_files)} PDF file(s)")
 
-    with tab_images:
+    else:  # Images
+        input_type_selected = "image"
+
         image_files = st.file_uploader(
             "Upload Images",
             type=['png', 'jpg', 'jpeg', 'gif', 'webp'],
@@ -731,11 +748,9 @@ with col_input:
             key="image_desc"
         )
 
-        input_type_selected = "image"
         if image_files:
             input_data = []
             for f in image_files:
-                # Save to temp file
                 suffix = '.' + f.name.split('.')[-1]
                 with tempfile.NamedTemporaryFile(delete=False, suffix=suffix) as tmp:
                     tmp.write(f.read())