Fix NameError: Import Error class from schemas

.pre-commit-config.yaml

@@ -33,6 +33,14 @@ repos:
         pass_filenames: false
         always_run: true
 
+      # Check for missing imports (prevent NameError bugs)
+      - id: check-import-usage
+        name: Check for classes/functions used without imports
+        entry: uv run python .pre-commit-hooks/check_import_usage.py
+        language: system
+        files: '^src/.*\.py$'
+        pass_filenames: true
+
       # Check A2A skill test coverage
       - id: a2a-skill-coverage
         name: Verify 100% A2A skill coverage

.pre-commit-hooks/check_import_usage.py

@@ -0,0 +1,204 @@
+#!/usr/bin/env python3
+"""Pre-commit hook to catch usage of classes/functions without imports.
+
+This prevents bugs like PR #332 where Error class was used but not imported,
+causing NameError in production.
+
+Usage:
+    python check_import_usage.py <file1> <file2> ...
+
+Exit codes:
+    0: All classes/functions used are imported
+    1: Found usage of classes/functions without imports
+"""
+
+import ast
+import sys
+from pathlib import Path
+
+
+class ImportCollector(ast.NodeVisitor):
+    """Collect all imported names from a module."""
+
+    def __init__(self):
+        self.imports: set[str] = set()
+
+    def visit_Import(self, node):
+        for alias in node.names:
+            name = alias.asname if alias.asname else alias.name
+            self.imports.add(name)
+        self.generic_visit(node)
+
+    def visit_ImportFrom(self, node):
+        for alias in node.names:
+            name = alias.asname if alias.asname else alias.name
+            self.imports.add(name)
+        self.generic_visit(node)
+
+
+class UsageCollector(ast.NodeVisitor):
+    """Collect usage of names that might need imports."""
+
+    def __init__(self):
+        self.usages: set[tuple[str, int]] = set()  # (name, line_number)
+
+    def visit_Call(self, node):
+        """Check function calls and class instantiations."""
+        name = self._get_name(node.func)
+        if name and name[0].isupper():  # Likely a class (PascalCase)
+            self.usages.add((name, node.lineno))
+        self.generic_visit(node)
+
+    def visit_Raise(self, node):
+        """Check raised exceptions."""
+        if node.exc and isinstance(node.exc, ast.Call):
+            name = self._get_name(node.exc.func)
+            if name:
+                self.usages.add((name, node.lineno))
+        self.generic_visit(node)
+
+    def _get_name(self, node) -> str | None:
+        """Extract name from node (handles Name and Attribute)."""
+        if isinstance(node, ast.Name):
+            return node.id
+        elif isinstance(node, ast.Attribute):
+            # For chained attributes like foo.bar.Baz, just get the first part
+            # since that's what needs to be imported
+            base = node
+            while isinstance(base, ast.Attribute):
+                base = base.value
+            if isinstance(base, ast.Name):
+                return base.id
+        return None
+
+
+def check_file(filepath: Path) -> list[str]:
+    """Check a file for usage of names without imports.
+
+    Returns:
+        List of error messages (empty if no issues)
+    """
+    try:
+        code = filepath.read_text()
+        tree = ast.parse(code, filename=str(filepath))
+    except SyntaxError as e:
+        return [f"{filepath}:{e.lineno}: Syntax error: {e.msg}"]
+    except Exception as e:
+        return [f"{filepath}: Failed to parse: {e}"]
+
+    # Collect imports
+    import_collector = ImportCollector()
+    import_collector.visit(tree)
+
+    # Collect usages
+    usage_collector = UsageCollector()
+    usage_collector.visit(tree)
+
+    # Find usages without imports
+    errors = []
+    builtins = {
+        "Exception",
+        "ValueError",
+        "TypeError",
+        "KeyError",
+        "AttributeError",
+        "RuntimeError",
+        "NameError",
+        "ImportError",
+        "NotImplementedError",
+        "StopIteration",
+        "IndexError",
+        "OSError",
+        "IOError",
+        "FileNotFoundError",
+        "PermissionError",
+        "TimeoutError",
+        "ConnectionError",
+        "dict",
+        "list",
+        "set",
+        "tuple",
+        "str",
+        "int",
+        "float",
+        "bool",
+        "bytes",
+        "object",
+        "type",
+        "len",
+        "range",
+        "enumerate",
+        "zip",
+        "map",
+        "filter",
+        "sum",
+        "min",
+        "max",
+        "abs",
+        "print",
+        "open",
+        "input",
+        "iter",
+        "next",
+    }
+
+    for name, lineno in usage_collector.usages:
+        # Skip builtins
+        if name in builtins:
+            continue
+
+        # Skip if imported
+        if name in import_collector.imports:
+            continue
+
+        # Skip common false positives
+        if name in ["self", "cls", "super"]:
+            continue
+
+        # Report potential missing import
+        errors.append(
+            f"{filepath}:{lineno}: '{name}' is used but may not be imported "
+            f"(add to imports or ignore if false positive)"
+        )
+
+    return errors
+
+
+def main():
+    """Check all provided files for missing imports."""
+    if len(sys.argv) < 2:
+        print("Usage: check_import_usage.py <file1> <file2> ...", file=sys.stderr)
+        return 1
+
+    all_errors = []
+    for filepath_str in sys.argv[1:]:
+        filepath = Path(filepath_str)
+
+        # Only check Python files
+        if filepath.suffix != ".py":
+            continue
+
+        # Skip test files (they have fixtures/mocks)
+        if "test" in filepath.parts:
+            continue
+
+        # Skip __init__ files
+        if filepath.name == "__init__.py":
+            continue
+
+        errors = check_file(filepath)
+        all_errors.extend(errors)
+
+    if all_errors:
+        print("\n❌ Found potential missing imports:\n", file=sys.stderr)
+        for error in all_errors:
+            print(f"  {error}", file=sys.stderr)
+        print("\n💡 Tip: Verify these classes/functions are imported at the top of the file.", file=sys.stderr)
+        print("   If they're defined locally or are false positives, this can be ignored.", file=sys.stderr)
+        return 1
+
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())

src/core/main.py

@@ -59,6 +59,7 @@
     CreativeAssignment,
     CreativeGroup,
     CreativeStatus,
+    Error,
     GetMediaBuyDeliveryRequest,
     GetMediaBuyDeliveryResponse,
     GetProductsRequest,