(janitor/dedupe): consolidate Postgres unique-violation detection

[kilo-code-bot]

Summary

Consolidates the duplicated "is this a PostgreSQL unique-constraint violation (SQLSTATE 23505)" logic scattered across apps/web into a single module, apps/web/src/lib/db-errors.ts.

Problem

Seven local implementations had already drifted:

Site	Behavior
webhook-triggers-router.ts	top-level code only
kiloclaw/access-codes.ts	top-level code only
manual-code-review-jobs.ts (getDatabaseErrorCode)	top-level code only
credit-campaigns-router.ts	top-level + one .cause level
quick-chat-router.ts	top-level + one .cause level
verified-domain-service.ts	top-level + recursive .cause
cloud-billing-skus-router.ts (postgresErrorCode)	recursive .cause
deletion-queue handlers ×2 (postgresErrorCode)	bounded .cause walk

Drizzle wraps the driver error in a DrizzleQueryError, so the SQLSTATE sits on .cause. The three "top-level only" sites silently missed wrapped violations; the one-level sites only handled a fixed depth.

Change

db-errors.ts now owns two functions:

• getPostgresErrorCode(error) — walks a bounded (depth 5) .cause chain and returns the SQLSTATE, disambiguated from unrelated code fields (e.g. Node's ENOTFOUND) via a [0-9A-Z]{5} shape check.
• isUniqueViolation(error) — getPostgresErrorCode(error) === '23505'.

All nine call sites import from the shared module instead of defining a local copy. Constraint-name-specific checks (linear/slack/user-deployments/webhook-events) and the richer redaction-oriented describeDatabaseError are intentionally left untouched.

Verification

• pnpm format on changed files — clean.
• oxlint on changed files — 0 warnings/errors.
• tsgo --noEmit (web) — exit 0.
• Added db-errors.test.ts (pure-function unit test; does not require Postgres). Note: the Jest global setup in this environment requires Postgres, so the suite could not be executed here, but the helper logic was exercised directly via tsx and all assertions pass.

Fixes the latent drift where wrapped unique violations were not detected in three call sites.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Executive Summary

The PR cleanly consolidates seven drifted Postgres unique-violation/error-code helpers into a single bounded, unit-tested apps/web/src/lib/db-errors.ts; all eleven changed call sites correctly preserve or improve prior detection behavior with no regressions found.

Files Reviewed (11 files)

• apps/web/src/lib/db-errors.ts
• apps/web/src/lib/db-errors.test.ts
• apps/web/src/lib/code-reviews/manual-code-review-jobs.ts
• apps/web/src/lib/kiloclaw/access-codes.ts
• apps/web/src/lib/organizations/verified-domain-service.ts
• apps/web/src/lib/user/deletion-queue/handlers/anonymize.ts
• apps/web/src/lib/user/deletion-queue/handlers/usage-prompt-prefixes.ts
• apps/web/src/routers/admin/cloud-billing-skus-router.ts
• apps/web/src/routers/admin/credit-campaigns-router.ts
• apps/web/src/routers/quick-chat-router.ts
• apps/web/src/routers/webhook-triggers-router.ts

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_{Reviewed by deepseek-v4.1-flash · Input: 0 · Output: 0 · Cached: 0}

_{Review guidance: REVIEW.md from base branch main}