Summary

Centralized DuckDB SQLite connection logic and implemented a validation-based retry mechanism for LLM-generated SQL queries.

Technical Details:

• Connection Management: Introduced a _duckdb_sqlite_connection context manager in src/lib/duckdb_utils.py. This centralizes the loading of the SQLite scanner extension, security configurations, and database attachment, ensuring connections are consistently closed.
• Validated SQL Generation: Modified generate_sql_query to include a retry loop (up to 3 attempts). The function now validates generated queries by executing them against the target database. If a query fails, the error message is passed back to the LLM to facilitate automated correction.
• LLM Instruction Updates: Updated system prompts to enforce strict output rules, including ISO 8601 timestamp formatting using strftime, case-insensitive text matching with LOWER(), and specific handling for different epoch precisions.
• Authorization Decorator Refactor: Restructured the require_access decorator in authz.py to provide separate sync and async wrappers. This ensures the access control logic executes correctly regardless of whether the decorated function is a coroutine.
• Dependencies: Added pytz to pyproject.toml and poetry.lock to support timezone-aware date conversions within the generated SQL queries.
• API Interface Change: Updated the generate_query endpoint in src/api/v1/files.py to pass the file object into the generation logic for query validation.