⚡ Bolt: Optimize SessionManager database operations

[charles-forsyth]

⚡ Bolt: Optimize SessionManager database operations

💡 What

Implemented a series of optimizations in the SessionManager class to streamline database operations:

• Redundant Initialization Cache: Added a class-level set _initialized_dbs to track and skip unnecessary schema checks and migrations for databases already processed in the current process.
• N+1 Query Fix: Updated list_sessions to use a LEFT JOIN on the sessions table itself, fetching parent session information in the primary query instead of executing a separate query for each child session.
• Batch Updates: Replaced individual UPDATE statements for crashed sessions with a single batched WHERE id IN (...) query, significantly reducing disk I/O and transaction overhead.
• Database Indexing: Added indexes for interaction_id, parent_id, and updated_at to ensure fast lookups, hierarchical traversal, and sorted listings.

🎯 Why

The SessionManager was performing several inefficient database operations that slowed down the CLI (especially the list command) and the recursive research process (where many agent instances are created). Each PRAGMA check and individual UPDATE commit added latency.

📊 Impact

Measured using benchmark scripts:

• Redundant Initializations: Reduced from 3 queries to 0 queries per subsequent SessionManager instance.
• list_sessions Performance: For a typical scenario with 6 sessions (1 parent, 5 children), queries were reduced from 12 down to 2.
• Scalability: Indexes ensure that performance remains consistent even as the session history grows to hundreds or thousands of entries.

🔬 Measurement

Verified using bench_init.py and bench_list_sessions.py (which proxy sqlite3 to count queries) and by running the full test suite with uv run pytest.

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PR created automatically by Jules for task 6751822011168121911 started by @charles-forsyth

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