sqlite-fault-tolerant-queries

SKILL.md

---
name: sqlite-fault-tolerant-queries
description: Use when managing database schema transitions, writing math rate routes, and creating server endpoints.
---

# SQLite Database Concurrency & Cold-Start Procedures

1. **Concurrency Protection:** Always query using the core database singleton connection mapping (`database.js`). Never spin up loose parallel `new sqlite3.Database()` handlers to avoid `SQLITE_BUSY` runtime lockups.
2. **Outlier Mitigation:** Refactor raw linear velocity averages to support moving averages or lookback metrics (e.g., filtering for the last 7 days) to minimize massive one-off sales anomalies.
3. **Zero-Transaction Defenses:** If an item's transaction log maps to `N/A` or zero historical velocity lines, invoke structural fallbacks (`Math.max(1, daysElapsed)`) to eradicate program-crashing mathematical division-by-zero errors.

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