Fix: Support ListCreativesRequest convenience fields with adcp 2.9.0

[bokelley]

Summary

Resolves the ListCreativesRequest convenience fields validation issue by switching from inheritance-based approach to composition pattern with proper Pydantic model configuration. This enables developers to pass flat convenience fields (media_buy_id, status, page, limit, sort_by, etc.) while maintaining AdCP specification compliance.

Key Changes:

• Modified AdCPBaseModel.__init__ to respect child class model_config overrides, enabling extra="allow" configuration for convenience fields
• Refactored ListCreativesRequest from inheritance to composition pattern using AdCPBaseModel directly
• Defined convenience fields as real Pydantic fields with exclude=True for automatic serialization exclusion
• Added create_list_creatives_request() factory function for type-safe convenience field mapping
• Fixed Filters import to use correct type from list_creatives_request module (was using wrong module)
• Updated list_creatives_impl() to use the factory function for consistent type handling
• Fixed all Package/AffectedPackage instantiations to include required status field (adcp 2.9.0)

Testing

• ✅ All 48 AdCP contract tests passing
• ✅ All 955 unit tests passing
• ✅ All 31 integration tests passing
• ✅ All 15 integration_v2 tests passing
• ✅ ListCreativesRequest direct instantiation with convenience fields
• ✅ Factory function preserves all convenience field values
• ✅ Convenience fields correctly excluded from serialization
• ✅ Datetime field conversion works (created_after, created_before)
• ✅ mypy type checking passes with no new errors

Technical Details

Root Cause

Pydantic v2 inheritance validation doesn't respect child class extra="forbid" overrides when the parent also has extra="forbid". The parent's configuration takes precedence.

Solution Architecture

1. Parent Intercept: AdCPBaseModel.__init__ now checks child class model_config before validating extra fields
2. Real Fields: Convenience fields are defined as Pydantic fields (not dynamic attributes)
3. Automatic Exclusion: Fields marked with exclude=True are automatically excluded from model_dump()
4. Factory Function: Maps flat parameters to structured AdCP objects before Pydantic validation
5. Type Safety: All parameters are properly typed for mypy and IDE support

Code Quality

• No code duplication between MCP and A2A paths
• Factory function centralizes convenience field mapping logic
• Type hints ensure compile-time safety
• Pre-commit hooks validate AdCP compliance
• All tests pass before push (pre-push hook validation)

Migration Notes

If you're using ListCreativesRequest directly with dict unpacking:

# Old approach (may have validation issues)
request = ListCreativesRequest(**convenience_fields_dict)

# New approach (recommended)
from src.core.schemas import create_list_creatives_request
request = create_list_creatives_request(**convenience_fields_dict)

Direct instantiation with convenience fields still works due to the model_config override:

request = ListCreativesRequest(
    media_buy_id="mb_123",
    status="approved",
    page=1,
    limit=50,
    filters=None,
    # ... other fields
)

Related Issues

• Follows adcp 2.9.0 upgrade with Package type changes
• Completes ListCreativesRequest convenience fields support
• Fixes Package instantiations missing required status field
• Documents technical debt for future adcp library improvements