fix: include seed dataset in builder repr for seed-only configs

[johnnygreco]

📋 Summary

Fixes DataDesignerConfigBuilder repr behavior so seed-only configurations no longer appear empty in interactive use. Adds a regression test to ensure seed datasets remain visible when no columns are configured.

🔄 Changes

🐛 Fixed

• Updated DataDesignerConfigBuilder.__repr__ to return DataDesignerConfigBuilder() only when both no columns and no seed dataset are configured.
• Preserves seed dataset visibility in notebook/REPL output after calling with_seed_dataset(...).

🧪 Tests

• Added test_repr_includes_seed_dataset_when_no_columns in packages/data-designer-config/tests/config/test_config_builder.py.
• Includes the behavior change in packages/data-designer-config/src/data_designer/config/config_builder.py.
• Commit reference: 7af89c1b.

🔍 Attention Areas

⚠️ Reviewers: Please pay special attention to the following:

• packages/data-designer-config/src/data_designer/config/config_builder.py - This is a public-facing repr path used in notebook and interactive workflows.

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🤖 Generated with AI

[greptile-apps]

Greptile Summary

Fixed DataDesignerConfigBuilder.__repr__ to display seed dataset information in seed-only configurations (no columns). Previously, the repr would return an empty DataDesignerConfigBuilder() string when no columns were configured, even if a seed dataset was present, making it invisible in notebooks and REPL environments.

• Changed condition from checking only len(self._column_configs) == 0 to len(self._column_configs) == 0 and self._seed_config is None
• Added regression test test_repr_includes_seed_dataset_when_no_columns to verify seed datasets remain visible

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• Single-line bug fix with clear logic improvement and comprehensive test coverage - changes only affect repr output visibility without altering functionality
• No files require special attention

Important Files Changed

Filename	Overview
packages/data-designer-config/src/data_designer/config/config_builder.py	Fixed __repr__ method to check both no columns AND no seed config before returning empty representation
packages/data-designer-config/tests/config/test_config_builder.py	Added regression test to verify seed dataset is shown in repr when no columns are configured

_{Last reviewed commit: 7af89c1}