# Patterns

## Entry Template

```
date: YYYY-MM-DD
author: <agent|name>
scope: <files/routes/features>
type: pattern
rationale: <why>
impact: <user/system/security/i18n/a11y>
status: accepted|superseded

Pattern:
When to use:
Example paths:
```

---

### P-001: Thin Pages, Reusable Logic Elsewhere

date: 2026-03-11  
author: Cline  
scope: `pages/`, `components/`, `lib/`, `actions/`  
type: pattern  
rationale: Improve maintainability and reduce route-level complexity.  
impact: Better testability and safer incremental changes.  
status: accepted

Pattern:
Keep route pages focused on composition and orchestration; place reusable behavior in `lib/`, `components/`, or `actions/`.

When to use:

- New features in existing routes
- Refactors reducing duplication across pages/components

Example paths:

- `pages/newappeal/**`
- `components/newappeal/**`
- `actions/index.js`

### P-002: EN/CY Parity for User-Facing Changes

date: 2026-03-11  
author: Cline  
scope: `locales/`, `i18n.js`, `next.config.js`, user-facing pages  
type: pattern  
rationale: Service requires bilingual consistency and reliable route behavior.  
impact: Prevents locale divergence and citizen confusion.  
status: accepted

Pattern:
Any user-facing change should include EN and CY text/route validation as part of done checks.

When to use:

- New/changed labels, messages, headings
- New/changed route aliases or rewrites

Example paths:

- `locales/en/**`, `locales/cy/**`
- `next.config.js`, `i18n.js`

### P-003: Shared Relay Policy via Middleware (No Endpoint Drift)

date: 2026-03-24  
author: Cline  
scope: `pages/api/middleware/relayForwarding.js`, `pages/api/endpoint/*_api.js` relay GET handlers  
type: pattern  
rationale: Keep reliability and logging policy centralized so endpoint handlers remain thin and behavior stays consistent as relay surface evolves.  
impact: Reduces duplication/drift in timeout/retry/error behavior and supports safer incremental endpoint migration/hardening.  
status: accepted

Pattern:
Implement retry/timeout/redacted structured logging in shared relay middleware and keep endpoint handlers focused on validation, transform, and route-level response contracts.

When to use:

- Any new or migrated relay-backed endpoint
- Any relay reliability/logging policy update

Example paths:

- `pages/api/middleware/relayForwarding.js`
- `pages/api/endpoint/getadvancedsearch_api.js`
- `pages/api/endpoint/getdnscoords_api.js`
- `tests/phase21/relay-forwarding-hardening.test.cjs`