# `Cairnloop.Automation.DraftGenerator.Anthropic`
[🔗](https://github.com/szTheory/cairnloop/blob/main/lib/cairnloop/automation/draft_generator/anthropic.ex#L1)

Reference `Cairnloop.Automation.DraftGenerator` backed by Anthropic's Claude
(Messages API). Composes a customer-support reply **only when grounding is strong**,
using the canonical Knowledge Base evidence the retrieval layer already gathered.

Fail-closed by construction — it delegates to `Cairnloop.Automation.ScoriaEngine`
(the deterministic default) in every case where it must not let a model guess:

  * grounding is `:clarification` or `:escalation` (not `:strong`) — ask for the
    missing detail / recommend handoff instead of composing a reply;
  * no API key is configured — degrade gracefully to the deterministic engine
    (mirrors `Cairnloop.Embedder.ExternalApi`'s no-key behaviour);
  * the Anthropic call errors or returns an unparseable body — never crash the
    `DraftWorker`; fall back so a draft still appears for the operator.

The proposal shape, grounding snapshot, evidence, and human-in-the-loop approval are
identical to the deterministic engine — only the `:strong`-grounding `customer_reply`
is model-composed (and still operator-reviewed before any send).

## Configuration

    # host config
    config :cairnloop, :draft_generator, Cairnloop.Automation.DraftGenerator.Anthropic

    # runtime.exs — secrets read at boot, never compiled in
    config :cairnloop, :anthropic_api_key, System.fetch_env!("ANTHROPIC_API_KEY")

Optional knobs (all have sensible defaults):

  * `:anthropic_model` — Claude model id (default `"claude-sonnet-4-6"`)
  * `:anthropic_max_tokens` — reply budget (default `1024`)
  * `:anthropic_req_options` — extra `Req` options merged into the request
    (the seam used by tests to inject a stub `plug:`)
  * `:conversation_lookup` — how to load the thread for prompt context
    (default `&Cairnloop.Chat.get_conversation!/1`; shared with `DraftWorker`)

The API key is also read from the `ANTHROPIC_API_KEY` env var when not set in config.

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*Consult [api-reference.md](api-reference.md) for complete listing*