Integration Layer

---
name: integration-layer
description: Infrastructure and integration patterns for src/app/integration, including Firebase/AngularFire usage, Data Connect codegen, repository adapters, DTO mapping, and streaming boundaries; use when touching persistence, external APIs, or platform SDKs.
---

# Integration Layer

## Intent
Implement external integrations (Firebase, Data Connect, HTTP, SDKs) behind stable ports so the rest of the app stays framework-agnostic.

## Layer Boundaries
- Only integration/infrastructure may import Firebase/AngularFire/DataConnect SDKs.
- Expose interfaces/tokens to Application; never expose platform types.

## Repository Adapters
- Implement repository ports with minimal mapping:
  - DTO <-> Domain mapping happens here (or in dedicated mappers within integration).
  - Keep mapping deterministic; normalize timestamps/IDs.

## Streams and Signals
- Integration may return Observables (streaming) or Promises (commands).
- Convert to signals at the Application boundary (store/facade), not in templates.
- Ensure cleanup: avoid manual subscriptions unless lifecycle-bound.

## Data Connect
- Treat generated SDK as read-only output.
- After schema changes, regenerate before app code changes.
- Enforce auth directives and least-privilege queries.

## Security
- Never trust client input.
- Keep secrets in env/secret manager, not in source.
- Avoid string-concatenated queries; use parameterized APIs.