Pattern Proposal: Pluggable Adapter Client

Summary

Uniform interface for external backend services allowing seamless swapping between production implementations and deterministic mock providers.

Candidate Pattern

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

Observed Signals

No specific signals listed.

Evidence

Supporting Evidence

• src/cas_runner/llm/litellm_client.py (LiteLLMClient) - Wraps external LiteLLM SDK calls.
• src/cas_runner/llm/mock_client.py (MockLLMClient) - Provides in-memory simulated responses with the same interface.

Scope Assessment

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

Rationale

• Intent: Isolate third-party network APIs behind a stable local contract to permit offline testing and vendor independence.
• Context: The governance framework interacts with external inference or analytical models, but testing and dry-run environments must operate offline without API tokens.
• Force: Direct coupling to external SDKs hampers integration testing in isolated CI environments.
• Force: Vendor API shifts ripple across the codebase if not isolated.

Traceability

Artifact source: proposed-patterns