Pattern Proposal: Provider Client Adapter

Summary

Abstracts external provider SDK calls behind dedicated client classes with drop-in test doubles.

Candidate Pattern

• ID: provider-client-adapter
• Classification: architectural
• Maturity: strategic_direction
• Type: emerging

Observed Signals

No specific signals listed.

Evidence

Supporting Evidence

• src/cas_runner/llm/litellm_client.py (LiteLLMClient) - Encapsulates external LiteLLM API interactions.
• src/cas_runner/llm/mock_client.py (MockLLMClient) - Provides deterministic test double adhering to the client interface.

Scope Assessment

• Evidence Strength: high
• Confidence: high
• Applies to: ideas-to-life-cas

Rationale

• Intent: Decouple domain and application logic from third-party vendor interfaces and enable deterministic local testing without external API calls.
• Context: The system relies on external SDKs for upstream processing (e.g., LiteLLM), but internal engines and automated CI tests require offline deterministic execution.
• Force: Direct imports of external client libraries couple business services to vendor SDKs
• Force: CI pipelines require offline hermetic test runs

Traceability

Artifact source: proposed-patterns