ADR 0022: Reuse UI API client connections via Streamlit resource cache

Date: 2026-01-15

Context: The Streamlit UI instantiated short-lived API clients frequently, preventing httpx connection pooling and adding avoidable per-request overhead; large error bodies could also produce noisy UI messages. Decision: Cache LoreleyAPIClient instances with st.cache_resource and enable HttpClient(reuse_connections=True); truncate non-2xx response bodies in HttpCallError messages. Constraints: Keep the implementation synchronous; avoid new runtime dependencies; preserve existing UI error semantics (status code + message). Consequences: UI calls reuse persistent HTTP connections, reducing overhead; error messages remain readable; timeouts keep a minimum clamp to avoid pathological values.