Pattern Proposal: LLM Provider Adapter Boundary

Summary

The llm subpackage exposes LiteLLMClient and MockLLMClient as adapter-style wrappers, separating the core from concrete provider or test implementations.

Candidate Pattern

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

Observed Signals

No specific signals listed.

Evidence

Supporting Evidence

• src/cas_runner/llm/litellm_client.py
• src/cas_runner/llm/mock_client.py

Scope Assessment

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

Rationale

• Intent: Treat LLM access as an infrastructure boundary so the rest of the system does not depend directly on a specific client or transport.
• Context: A Python project that integrates LiteLLM and also needs deterministic test doubles.
• Force: External provider libraries are volatile
• Force: Tests need a non-network or non-live client
• Force: Upper layers should not care how messages are transported

Traceability

Artifact source: proposed-patterns