Fix encoded statistical model detail links

routes/main_routes.py

@@ -7,6 +7,13 @@
 from collections import OrderedDict
 from urllib.parse import unquote
 main = Blueprint('main', __name__)
+
+
+def _decode_path_name(name):
+    """Decode one path segment left encoded after Flask's URL decoding."""
+    return unquote(name)
+
+
 # -----------------------------------------------------------------------------
 # MODEL GROUPING FOR NAVIGATION DROPDOWN
 # -----------------------------------------------------------------------------
@@ -667,7 +674,7 @@ def models_in_group(group_name):
     model_database = current_app.config.get('MODEL_DATABASE', {})
     # Some clients and previously rendered links can encode the path segment
     # twice, leaving a literal ``%20`` after Flask's first URL decode.
-    group_name = unquote(group_name)
+    group_name = _decode_path_name(group_name)
     # Validate group_name
     if group_name not in MODEL_GROUPS:
         flash(f"Invalid model group: {group_name}", "danger")
@@ -690,6 +697,7 @@ def models_in_group(group_name):
 def model_details(model_name):
     """Display details for a specific model"""
     try:
+        model_name = _decode_path_name(model_name)
         model_info = get_model_details(model_name)
         if model_info:
             return render_template('model_details.html',
@@ -703,6 +711,7 @@ def model_details(model_name):
 def model_interpretation(model_name):
     """Display interpretation guide for a specific model"""
     try:
+        model_name = _decode_path_name(model_name)
         model_info = get_model_details(model_name)
         if not model_info:
             return render_template('error.html', error="Model not found")
@@ -720,6 +729,7 @@ def model_interpretation(model_name):
 def download_interpretation(model_name):
     """Generate and download interpretation guide as HTML file"""
     try:
+        model_name = _decode_path_name(model_name)
         model_info = get_model_details(model_name)
         if not model_info:
             return render_template('error.html', error="Model not found")

tests/test_main_routes.py

@@ -1,7 +1,12 @@
 """
 Test the main routes and analysis functionality.
 """
+import sys
+from types import ModuleType
+
 from models import Analysis
+
+
 class TestMainRoutes:
     """Test main application routes."""
     def test_home_page(self, client):
@@ -20,6 +25,41 @@ def test_double_encoded_model_group_url(self, client):
         assert response.status_code == 200
         assert b'Invalid model group' not in response.data
         assert b'Linear Regression' in response.data
+
+    def test_double_encoded_model_detail_urls(self, client, monkeypatch):
+        """Encoded model links work across detail and interpretation routes."""
+        interpretation_module = ModuleType('utils.interpretation')
+        interpretation_module.generate_interpretation_data = (
+            lambda _model_name, _model_info: {}
+        )
+        monkeypatch.setitem(
+            sys.modules,
+            'utils.interpretation',
+            interpretation_module,
+        )
+
+        detail_response = client.get('/model/Linear%2520Regression')
+        interpretation_response = client.get(
+            '/model/Linear%2520Regression/interpretation'
+        )
+        download_response = client.get(
+            '/model/Linear%2520Regression/download-interpretation'
+        )
+
+        for response in (
+            detail_response,
+            interpretation_response,
+            download_response,
+        ):
+            assert response.status_code == 200
+            assert b'Model not found' not in response.data
+
+        assert b'Linear Regression' in detail_response.data
+        assert (
+            'Linear_Regression_interpretation_guide.html'
+            in download_response.headers['Content-Disposition']
+        )
+
     def test_analysis_form_submission_authenticated(self, authenticated_client, sample_analysis_data, app):
         """Test analysis form submission with authenticated user."""
         response = authenticated_client.post('/results', data=sample_analysis_data, follow_redirects=True)