Both narrow indexes are fully covered by the existing (source, kind)
and (target, kind) composites via SQLite's left-prefix scan, so
they're dead weight on every write. Empirical measurements (from the
spike script in PR #122 on a 50K-node / 250K-edge synthetic DB):
- DB size: 34.7 MB → 27.0 MB (-22.2%)
- Bulk insert (250K edges): 590ms → 431ms (1.37× faster)
- source/target lookup latency: no regression
Adds migration v4 to drop both on existing databases; fresh-DB schema
no longer creates them.
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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