---
title: LLM configuration
description: Configure KTX LLM providers, model roles, and prompt caching.
---

KTX uses the top-level `llm` block in `ktx.yaml` for text generation,
structured extraction, and ingest or memory agent loops.

## Backends

Set `llm.provider.backend` to one of these values:

- `anthropic`: Use the Anthropic API through `ANTHROPIC_API_KEY` or the
  configured `api_key` reference.
- `vertex`: Use Vertex AI Anthropic models through Google Cloud credentials.
- `gateway`: Use AI Gateway-compatible Anthropic model ids.
- `claude-code`: Use your local Claude Code session through the Claude Agent
  SDK. KTX removes provider-routing environment variables from Claude Code
  child processes, so this backend doesn't silently fall back to
  `ANTHROPIC_API_KEY`, Vertex, Gateway, or Bedrock credentials.

## Claude Code

Use aliases or full Claude model IDs in `llm.models`:

```yaml
llm:
  provider:
    backend: claude-code
  models:
    default: sonnet
    triage: haiku
    candidateExtraction: sonnet
    curator: sonnet
    reconcile: sonnet
    repair: sonnet
```

During setup, choose the Claude Code backend interactively or pass the model in
automation:

```bash
ktx setup --llm-backend claude-code --llm-model opus --no-input
```

For Claude Code, `sonnet`, `opus`, and `haiku` map to the current KTX defaults.
You can also pass a full Claude model ID, such as `claude-opus-4-7`.

`claude-code` keeps KTX tool boundaries intact. KTX exposes only the MCP tools
needed for the current KTX agent loop, disables Claude Code built-in tools,
keeps plugins empty, and denies every non-KTX tool request through
`canUseTool`. The Claude Agent SDK may still report host-discovered slash
commands, skills, and subagent names in init metadata; that metadata is not an
execution grant for KTX agent loops.

## Prompt caching

`llm.promptCaching` has partial parity on `claude-code`. KTX doesn't pass
Anthropic cache-control markers to the Claude Agent SDK. Status and doctor warn
when you configure prompt-cache TTL, tool, or history fields that the Claude
Agent SDK backend ignores.