openai-completions.ts, anthropic.ts, openai-responses.ts, openai-codex-responses.ts, amazon-bedrock.ts, google.ts, google-vertex.ts, google-shared.ts, mistral.ts, azure-openai-responses.ts, faux.ts, cloudflare.ts. Each exports stream<Provider>() returning AssistantMessageEventStream, plus option interfaces and conversion functions. Lazy-loaded in register-builtins.ts. Compatibility settings (OpenAICompletionsCompat, AnthropicMessagesCompat) override auto-detected behavior.
Key patterns: no inline imports; errors encoded in stream (done/error events) not thrown; transform-messages.ts converts between provider message shapes.
Related: AI index, Stream event