test(web): assert 400 exactly, and prove valid input is accepted

Both review points were right, and the first is the failure mode this file
exists to catch.

Accepting any 4xx meant a 404 would have passed. Renaming one of these routes
would have left the test green while it tested nothing -- the same "looks like
coverage, points somewhere safe" shape that hid the composer injections. Now
asserts exactly 400.

Both infinity signs are exercised for every route. int() raises OverflowError
either way, but only +Infinity was in the original report, and a guard that
special-cased the sign would have passed a one-sided test.

The valid-input test previously asserted "not a 400", which did not show what
it claimed: the mocked save path fails for any input, so that assertion held
whether or not validation had accepted the value. It now gives load_config a
real dict and stubs _save_config_atomic, so the endpoint reaches its success
response and the test can assert 200 -- which only happens if the value passed
validation.

8 of the 11 checks fail with OverflowError removed from the except tuples.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01STMbQE4YctTacQXfbYqKuW

test/test_api_v3_non_finite_numbers.py

@@ -0,0 +1,85 @@
+"""Non-finite JSON numbers must be rejected, not raise.
+
+json.loads accepts Infinity/-Infinity/NaN by default (they are not valid JSON,
+but Python's parser emits them) and Flask's get_json passes them straight
+through. int(float('inf')) raises OverflowError, which is neither ValueError
+nor TypeError -- so validation blocks that carefully caught those let it
+through and Flask turned it into a 500.
+
+The damage was not the status code. /config/dim-schedule answered with
+CONFIG_SAVE_FAILED and suggested "Check file permissions on config directory"
+and "Check available disk space" for what was actually an invalid number.
+
+NaN already returned 400 (int(nan) raises ValueError), which is why this only
+showed up for the infinities.
+"""
+import sys
+from pathlib import Path
+
+import pytest
+
+sys.path.insert(0, str(Path(__file__).parent.parent))
+
+from test._api_v3_test_helpers import api_v3_client, api_v3_module  # noqa: F401,E402
+
+
+#: (route, field) that returned 500 before OverflowError was caught. Both
+#: infinity signs are exercised: int() raises OverflowError for either, but
+#: only one of them was in the original report, and a guard that special-cased
+#: the sign would pass a one-sided test.
+NON_FINITE_ROUTES = [
+    ('/api/v3/config/dim-schedule', 'dim_brightness'),
+    ('/api/v3/errors/clear', 'max_age_hours'),
+    ('/api/v3/config/main', 'multiplexing'),
+    ('/api/v3/config/main', 'row_address_type'),
+]
+NON_FINITE_CASES = [
+    (route, '{"%s": %s}' % (field, literal))
+    for route, field in NON_FINITE_ROUTES
+    for literal in ('Infinity', '-Infinity')
+]
+
+
+@pytest.mark.parametrize("route,body", NON_FINITE_CASES)
+def test_infinity_is_a_client_error_not_a_server_error(api_v3_client, route, body):
+    """Exactly 400, not merely "some 4xx".
+
+    Accepting any 4xx would let a 404 pass, so renaming one of these routes
+    would leave the test green while testing nothing -- the failure mode this
+    whole file exists to catch.
+    """
+    response = api_v3_client.post(route, data=body, content_type='application/json')
+    assert response.status_code == 400, (
+        f"{route} with {body} answered {response.status_code}; expected 400"
+    )
+
+
+@pytest.mark.parametrize("route,body", [
+    ('/api/v3/config/dim-schedule', '{"dim_brightness": NaN}'),
+    ('/api/v3/errors/clear', '{"max_age_hours": NaN}'),
+])
+def test_nan_is_also_a_client_error(api_v3_client, route, body):
+    """int(nan) raises ValueError so this path already worked -- pinned so a
+    refactor that narrows the except tuple cannot quietly break it."""
+    response = api_v3_client.post(route, data=body, content_type='application/json')
+    assert response.status_code == 400
+
+
+def test_a_valid_number_is_accepted(api_v3_client, api_v3_module, monkeypatch):
+    """Prove the widened except did not start swallowing ordinary input.
+
+    Asserting "not a 400" would not show that: the mocked save path fails for
+    any input, so the assertion would hold even if validation had rejected the
+    value. Give load_config a real dict and stub the atomic save, and the
+    endpoint reaches its success response -- which only happens if 30 passed
+    validation.
+    """
+    api_v3_module.api_v3.config_manager.load_config.return_value = {}
+    monkeypatch.setattr(api_v3_module, '_save_config_atomic',
+                        lambda *a, **k: (True, ''))
+    response = api_v3_client.post(
+        '/api/v3/config/dim-schedule',
+        data='{"dim_brightness": 30}',
+        content_type='application/json',
+    )
+    assert response.status_code == 200, response.get_data(as_text=True)[:200]

web_interface/blueprints/api_v3.py

@@ -597,7 +597,7 @@ def save_dim_schedule_config():
                 dim_brightness = 30
             else:
                 dim_brightness = int(dim_brightness_raw)
-        except (ValueError, TypeError):
+        except (ValueError, TypeError, OverflowError):
             return error_response(
                 ErrorCode.VALIDATION_ERROR,
                 "dim_brightness must be an integer between 0 and 100",
@@ -797,7 +797,7 @@ def save_main_config():
                 }), 400
             try:
                 target_fps = int(raw_target_fps)
-            except (ValueError, TypeError):
+            except (ValueError, TypeError, OverflowError):
                 return jsonify({
                     'status': 'error',
                     'message': "Invalid value for target_fps: must be an integer"
@@ -867,7 +867,7 @@ def save_main_config():
                     mux_val = int(data['multiplexing'])
                     if mux_val < 0 or mux_val > 22:
                         return jsonify({'status': 'error', 'message': f"Invalid multiplexing value '{data['multiplexing']}'. Must be an integer from 0 to 22."}), 400
-                except (ValueError, TypeError):
+                except (ValueError, TypeError, OverflowError):
                     return jsonify({'status': 'error', 'message': f"Invalid multiplexing value '{data['multiplexing']}'. Must be an integer from 0 to 22."}), 400
 
             # Validate pixel_mapper_config (free-form mapper string, e.g. "U-mapper;Rotate:90")
@@ -885,7 +885,7 @@ def save_main_config():
                     rat_val = int(data['row_address_type'])
                     if rat_val < 0 or rat_val > 4:
                         return jsonify({'status': 'error', 'message': f"Invalid row_address_type '{data['row_address_type']}'. Must be an integer from 0 to 4."}), 400
-                except (ValueError, TypeError):
+                except (ValueError, TypeError, OverflowError):
                     return jsonify({'status': 'error', 'message': f"Invalid row_address_type '{data['row_address_type']}'. Must be an integer from 0 to 4."}), 400
 
             # Handle hardware settings
@@ -910,7 +910,7 @@ def save_main_config():
                     if rp1_val not in (0, 1):
                         return jsonify({'status': 'error', 'message': "rp1_rio must be 0 (PIO) or 1 (RIO)"}), 400
                     current_config['display']['runtime']['rp1_rio'] = rp1_val
-                except (ValueError, TypeError):
+                except (ValueError, TypeError, OverflowError):
                     return jsonify({'status': 'error', 'message': "rp1_rio must be 0 or 1"}), 400
 
             # Handle checkboxes - coerce to bool to ensure proper JSON types
@@ -963,7 +963,7 @@ def save_main_config():
                 copies = None
                 try:
                     copies = int(data['double_sided_copies'])
-                except (ValueError, TypeError):
+                except (ValueError, TypeError, OverflowError):
                     if enabled:
                         return jsonify({'status': 'error', 'message': "Double-sided copies must be an integer"}), 400
                 if copies is not None and not (2 <= copies <= 8):
@@ -1036,7 +1036,7 @@ def save_main_config():
             if data.get('vegas_extend_threshold_screens') not in ('', None):
                 try:
                     screens = float(data['vegas_extend_threshold_screens'])
-                except (ValueError, TypeError):
+                except (ValueError, TypeError, OverflowError):
                     return jsonify({
                         'status': 'error',
                         'message': "Invalid value for vegas_extend_threshold_screens: "
@@ -1053,7 +1053,7 @@ def save_main_config():
             if data.get('vegas_max_plugin_width_ratio') not in ('', None):
                 try:
                     ratio = float(data['vegas_max_plugin_width_ratio'])
-                except (ValueError, TypeError):
+                except (ValueError, TypeError, OverflowError):
                     return jsonify({
                         'status': 'error',
                         'message': "Invalid value for vegas_max_plugin_width_ratio: "
@@ -1101,7 +1101,7 @@ def save_main_config():
                         continue
                     try:
                         int_value = int(raw_value)
-                    except (ValueError, TypeError):
+                    except (ValueError, TypeError, OverflowError):
                         return jsonify({
                             'status': 'error',
                             'message': f"Invalid value for {field_name}: must be an integer"
@@ -1153,7 +1153,7 @@ def save_main_config():
                     if not (1024 <= port_val <= 65535):
                         return jsonify({'status': 'error', 'message': "sync_port must be between 1024 and 65535"}), 400
                     current_config['sync']['port'] = port_val
-                except (ValueError, TypeError):
+                except (ValueError, TypeError, OverflowError):
                     return jsonify({'status': 'error', 'message': "sync_port must be an integer"}), 400
 
             if "sync_follower_position" in data:
@@ -1197,7 +1197,7 @@ def save_main_config():
                 raw_value = data.pop(field)
                 try:
                     int_value = int(raw_value)
-                except (ValueError, TypeError):
+                except (ValueError, TypeError, OverflowError):
                     return jsonify({'status': 'error',
                                     'message': f"Invalid duration for {field}: must be an integer"}), 400
                 current_config['display']['display_durations'][field] = int_value
@@ -1220,7 +1220,7 @@ def save_main_config():
                     continue
                 try:
                     int_value = int(raw_value)
-                except (ValueError, TypeError):
+                except (ValueError, TypeError, OverflowError):
                     return jsonify({'status': 'error',
                                     'message': f"Invalid duration for mode '{mode_key}': must be an integer"}), 400
                 current_config['display']['display_durations'][mode_key] = int_value
@@ -5118,7 +5118,7 @@ def save_plugin_config():
                                                                 converted_array.append(int(v))
                                                             else:
                                                                 converted_array.append(float(v))
-                                                        except (ValueError, TypeError):
+                                                        except (ValueError, TypeError, OverflowError):
                                                             converted_array.append(v)
                                                     else:
                                                         converted_array.append(v)
@@ -5143,7 +5143,7 @@ def save_plugin_config():
                                                         converted_array.append(int(v))
                                                     else:
                                                         converted_array.append(float(v))
-                                                except (ValueError, TypeError):
+                                                except (ValueError, TypeError, OverflowError):
                                                     converted_array.append(v)
                                             else:
                                                 converted_array.append(v)
@@ -5180,7 +5180,7 @@ def save_plugin_config():
                                                                 converted_array.append(int(v))
                                                             else:
                                                                 converted_array.append(float(v))
-                                                        except (ValueError, TypeError):
+                                                        except (ValueError, TypeError, OverflowError):
                                                             converted_array.append(v)
                                                     else:
                                                         converted_array.append(v)
@@ -5204,7 +5204,7 @@ def save_plugin_config():
                                                         converted_array.append(int(v))
                                                     else:
                                                         converted_array.append(float(v))
-                                                except (ValueError, TypeError):
+                                                except (ValueError, TypeError, OverflowError):
                                                     converted_array.append(v)
                                             else:
                                                 converted_array.append(v)
@@ -5371,7 +5371,7 @@ def save_plugin_config():
                                         if isinstance(v, str):
                                             try:
                                                 converted.append(int(v) if item_type == 'integer' else float(v))
-                                            except (ValueError, TypeError):
+                                            except (ValueError, TypeError, OverflowError):
                                                 converted.append(v)
                                         else:
                                             converted.append(v)
@@ -5496,7 +5496,7 @@ def save_plugin_config():
                             try:
                                 normalized[key] = int(value_stripped)
                                 continue
-                            except (ValueError, TypeError):
+                            except (ValueError, TypeError, OverflowError):
                                 pass
                         elif isinstance(value, (int, float)):
                             normalized[key] = int(value)
@@ -5514,7 +5514,7 @@ def save_plugin_config():
                             try:
                                 normalized[key] = float(value_stripped)
                                 continue
-                            except (ValueError, TypeError):
+                            except (ValueError, TypeError, OverflowError):
                                 pass
                         elif isinstance(value, (int, float)):
                             normalized[key] = float(value)
@@ -5569,7 +5569,7 @@ def save_plugin_config():
                                     try:
                                         normalized_array.append(int(v))
                                         continue
-                                    except (ValueError, TypeError):
+                                    except (ValueError, TypeError, OverflowError):
                                         pass
                                 elif isinstance(v, (int, float)):
                                     normalized_array.append(int(v))
@@ -5579,7 +5579,7 @@ def save_plugin_config():
                                     try:
                                         normalized_array.append(float(v))
                                         continue
-                                    except (ValueError, TypeError):
+                                    except (ValueError, TypeError, OverflowError):
                                         pass
                                 elif isinstance(v, (int, float)):
                                     normalized_array.append(float(v))
@@ -5595,7 +5595,7 @@ def save_plugin_config():
                             if isinstance(v, str):
                                 try:
                                     normalized_array.append(int(v))
-                                except (ValueError, TypeError):
+                                except (ValueError, TypeError, OverflowError):
                                     normalized_array.append(v)
                             elif isinstance(v, (int, float)):
                                 normalized_array.append(int(v))
@@ -5609,7 +5609,7 @@ def save_plugin_config():
                             if isinstance(v, str):
                                 try:
                                     normalized_array.append(float(v))
-                                except (ValueError, TypeError):
+                                except (ValueError, TypeError, OverflowError):
                                     normalized_array.append(v)
                             else:
                                 normalized_array.append(v)
@@ -5632,7 +5632,7 @@ def save_plugin_config():
                     if isinstance(value, str):
                         try:
                             normalized[key] = int(value)
-                        except (ValueError, TypeError):
+                        except (ValueError, TypeError, OverflowError):
                             normalized[key] = value
                     else:
                         normalized[key] = value
@@ -5641,7 +5641,7 @@ def save_plugin_config():
                     if isinstance(value, str):
                         try:
                             normalized[key] = float(value)
-                        except (ValueError, TypeError):
+                        except (ValueError, TypeError, OverflowError):
                             normalized[key] = value
                     else:
                         normalized[key] = value
@@ -6779,7 +6779,7 @@ def get_font_preview() -> tuple[Response, int] | Response:
         # Safe integer parsing for size
         try:
             size = int(request.args.get('size', 12))
-        except (ValueError, TypeError):
+        except (ValueError, TypeError, OverflowError):
             return jsonify({'status': 'error', 'message': 'Invalid font size'}), 400
 
         if not font_filename:
@@ -8360,7 +8360,7 @@ def clear_old_errors():
                     context={'provided_value': raw_max_age},
                     status_code=400
                 )
-        except (ValueError, TypeError):
+        except (ValueError, TypeError, OverflowError):
             return error_response(
                 error_code=ErrorCode.INVALID_INPUT,
                 message="max_age_hours must be a valid integer",