Pattern Proposal: Pluggable Infrastructure Client Adapter

Summary

Adapter pattern isolating external provider implementations behind uniform client contracts.

Candidate Pattern

• ID: pluggable-infrastructure-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) - Production implementation wrapping LiteLLM API.
• src/cas_runner/llm/mock_client.py (MockLLMClient) - In-memory test double mimicking client behavior without external network access.

Scope Assessment

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

Rationale

• Intent: Decouple external provider calls from business execution and allow seamless test stubbing.
• Context: The system communicates with external model APIs but requires hermetic offline runs for local tests and CI validation.
• Force: Third-party API dependencies introduce network flakiness and cost during test runs.
• Force: Runtime configuration must switch between mock and real execution transparently.

Traceability

Artifact source: proposed-patterns