FastRAG API — Components Diagram

Fail-closed vs fail-open

QueryPipeline calls each collaborator and adapter directly: check guardrails, resolve config, embed, retrieve, rerank, correct (CRAG), stream the answer through the citation buffer, then write the cache and record the trace
Registry, embedding, retrieval, rerank and generation raise PipelineUnavailable → HTTP 503 or an SSE error event
Cache reads/writes and tracing fail open; an unreachable Redis becomes a no-op

Adapters are chosen at startup

cloud profile → Jina embed + rerank; local → FastEmbed ONNX models
FallbackGenerator switches to OpenRouter only if the primary fails before its first token
Hosted calls go through the harness: jittered retry, circuit breaker, request deadline

Not on the query path

CRAG itself re-embeds, re-retrieves and reranks a rewritten query (edges omitted for clarity)
Guardrails.check_safety_model exists but nothing calls it
The admin router, RQ queue and worker only run in the compose stack