[feat] allow using claude code as a client<llm>

[attilah]

Product

BAML

Problem Statement / Use Case

Make a locally installed and configured (and logged in) claude code cli available as a baml client

Proposed Solution

Add claude code as a new client type within the runtime and ensure that client options within baml covering a sane set of CLI options for claude
code.

Alternative Solutions

No response

Additional Context

I saw #2229 but it was closed without response, I hope this sheds more light on the request. I could also imagine codex support the same way.

[linear]

BAML-525

[sxlijin]

Thanks for the FR! This is a lot more specific than #2229, and this would definitely be cool.

Do you know if there are docs anywhere for how to piggyback off claude code / codex for this?

[attilah]

@sxlijin I'd use Codex SDK and Claude SDK for this but as a quick PoC probably just integrating print mode would be enough: claude -p "explain what is BoundaryML's BAML in 2 sentences like a 5yo" --output-format json

{
    "type": "result",
    "subtype": "success",
    "is_error": false,
    "duration_ms": 4122,
    "duration_api_ms": 16579,
    "num_turns": 1,
    "result": "BAML is like a special language that helps computers understand what you want them to say and do when talking to AI friends (like me!). It's like giving the computer a recipe with exact instructions so it knows how to ask questions and get answers in just the right way.",
    "session_id": "a6349459-6127-481f-b26e-a298b32d7fd1",
    "total_cost_usd": 0.1268645,
    "usage": {
        "input_tokens": 3,
        "cache_creation_input_tokens": 27775,
        "cache_read_input_tokens": 0,
        "output_tokens": 60,
        "server_tool_use": {
            "web_search_requests": 0,
            "web_fetch_requests": 0
        },
        "service_tier": "standard",
        "cache_creation": {
            "ephemeral_1h_input_tokens": 0,
            "ephemeral_5m_input_tokens": 27775
        }
    },
    "modelUsage": {
        "claude-haiku-4-5-20251001": {
            "inputTokens": 4699,
            "outputTokens": 317,
            "cacheReadInputTokens": 0,
            "cacheCreationInputTokens": 0,
            "webSearchRequests": 0,
            "costUSD": 0.006284,
            "contextWindow": 200000
        },
        "claude-sonnet-4-5-20250929": {
            "inputTokens": 6,
            "outputTokens": 71,
            "cacheReadInputTokens": 0,
            "cacheCreationInputTokens": 31866,
            "webSearchRequests": 0,
            "costUSD": 0.12058050000000001,
            "contextWindow": 200000
        }
    },
    "permission_denials": [],
    "uuid": "..."
}

[sxlijin]

Ooh, that's good to know, thanks!