init: 클린 아키텍처 백엔드

docs/runbooks/db-query-canceled.md

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+---
+title: Runbook — DB_QUERY_CANCELED (쿼리 취소)
+category: TRANSIENT_DEPENDENCY
+error_codes: [DB_QUERY_CANCELED]
+severity: P2
+owner: oncall
+last_updated: 2026-06-15
+status: stub
+---
+
+# Runbook: DB_QUERY_CANCELED (`runbook://db/query-canceled`)
+
+## Symptoms
+
+- HTTP 503 with `error.code=DB_QUERY_CANCELED`
+- SQLState 57014; query exceeds statement timeout
+
+## Diagnosis
+
+- Check `statement_timeout` in Postgres
+- Identify slow queries in `pg_stat_statements`
+
+## Action
+
+- Optimize slow query or add index
+- Adjust statement timeout if query is legitimately long
+
+## Escalation
+
+- Escalate to DBA for query optimization if recurring
+
+---
+
+> **Stub**: Phase D2 — author body after domain adoption. (feature-operational-runbook-contract D9)