Skill: ReqLLM Adapter (Serena/Codex)

Goal: Give agents a compact, provider-agnostic recipe for using req_llm in BEAM projects (OpenCode/Serena/Codex). Keep opt-in and align with docs/req_llm.md.

When to use

• Project wants a unified LLM client without bespoke HTTP calls.
• Need standard prompts for generate_text/3, stream_text/3, or generate_object/4.
• Need to surface usage/cost telemetry and keep keys out of git.

Quick setup (per project)

1. Ensure dep is available (templates mark optional): {:req_llm, "~> 1.5", optional: true}.
2. Keys via env or .env (preferred): OPENAI_API_KEY, ANTHROPIC_API_KEY, OPENROUTER_API_KEY, or REQ_LLM_PROVIDERS_JSON.
3. For local endpoints (LM Studio/Ollama with OpenAI plugin) set REQ_LLM_OPENAI_BASE_URL and a dummy key.
4. Add a thin wrapper module (or copy from templates/llm/req_llm_example.ex) and wire telemetry hook below.

Prompt snippets (drop into agent messages)

• Text:
  Copy

  Use ReqLLM.generate_text/3 with opts:
  - :provider (e.g., :openai, :anthropic, :openrouter)
  - :model (string)
  - :messages (list of %{role: :user|:assistant|:system, content: string})
  - :max_output_tokens (optional)
  Return {:ok, %ReqLLM.Response{content, usage}} or {:error, reason}.
  

• Streaming:
  Copy

  Use ReqLLM.stream_text/3. Consume stream of %ReqLLM.StreamChunk{type: :content|:tool_call|:meta, data: ...}.
  Accumulate content chunks; handle :tool_call separately.
  

• Object generation:
  Copy

  Use ReqLLM.generate_object/4 with a JSON schema map under :response_schema.
  Expect {:ok, %{object: map(), usage: usage}} or {:error, reason}.
  

Telemetry hook

:telemetry.attach(
  "req-llm-usage",
  [:req_llm, :token_usage],
  fn _event, measurements, metadata, _ ->
    Logger.info("req_llm usage", measurements: measurements, metadata: metadata)
  end,
  nil
)

Measurements include tokens and cost fields; safe to forward to OTEL/Logger.

Guardrails

• Keep HTTP/1 Finch pools unless you’ve validated HTTP/2 with your stack.
• Never commit keys; prefer env/direnv/Nix devshell vars.
• Mark the dep optional to avoid pulling LLM libs when unused.
• For CI, skip mix req_llm.model_sync unless explicitly needed.

Validation checklist (when enabled)

• mix format
• mix credo --strict
• mix test
• Optional: REQ_LLM_FIXTURES_MODE=record mix test (with keys)
• Optional: mix dialyzer (if PLTs available)

Pointers

• Full doc: docs/req_llm.md
• Example module: templates/llm/req_llm_example.ex