castellum

AI pipeline orchestration with automatic async I/O, CPU, and GPU management.

Install

pip install castellum
# With OpenAI support:
pip install "castellum[openai]"
# With Anthropic support:
pip install "castellum[anthropic]"
# Everything:
pip install "castellum[all]"

Quick start

from castellum import ai_task, pipeline, Runtime
from castellum.backends.remote.openai import OpenAIClient

client = OpenAIClient()

@ai_task(kind="preprocess")
def chunk_docs(docs: list[str]) -> list[str]:
    return [c for doc in docs for c in doc.split("\n\n")]

@ai_task(kind="embedding", device="cuda", batchable=True, max_batch_size=128)
def embed_chunks(chunks: list[str]) -> list[list[float]]:
    return local_embedder.encode(chunks)

@ai_task(kind="llm_remote", model="gpt-4.1-mini")
async def answer(question: str, context: str) -> str:
    return await client.chat(
        model="gpt-4.1-mini",
        messages=[{"role": "user", "content": f"{context}\n\n{question}"}],
    )

@pipeline
async def rag_pipeline(docs: list[str], question: str) -> str:
    chunks = chunk_docs(docs)
    vecs = await embed_chunks.map(chunks, preferred_batch_size=64)
    context = "\n".join(str(v) for v in vecs[:5])
    return await answer(question, context)

runtime = Runtime(
    max_cpu_workers=8,
    max_gpu_workers=2,
    max_concurrent_remote_calls=10,
    tokens_per_minute_limit=80_000,
)

result = await runtime.run(rag_pipeline, docs, question)
await runtime.aclose()

# Or stream tokens from an LLM task:
@ai_task(kind="llm_remote", model="gpt-4.1-mini", stream=True)
async def stream_answer(question: str, context: str):
    async for chunk in client.stream_chat(...):
        yield chunk

@pipeline
async def streaming_pipeline(docs: list[str], question: str):
    chunks = chunk_docs(docs)
    vecs = await embed_chunks.map(chunks, preferred_batch_size=64)
    async for token in stream_answer(question, str(vecs[:5])):
        yield token

async with Runtime() as runtime:
    gen = await runtime.run(streaming_pipeline, docs, "What?")
    async for token in gen:
        print(token, end="", flush=True)

Core concepts

Running tests

# Install with dev dependencies
pip install "castellum[dev]"

# Run all tests
pytest

# Run remote backend tests (requires API endpoint)
export OPENAI_BASE_URL=http://localhost:20128/v1
export OPENAI_API_KEY=sk-...
pytest tests/backends/

License

Unlicense — public domain. See LICENSE.