Castia SDK map

Application code should stay small. Castia keeps the agent loop, protocols, local testing, evaluation, optimization, and deployment handoff on the same rail.

Shape of an app

from pathlib import Path

from castia import Agent, Depends, Model, Teams, configured_model, load_agent_config

app = Agent(name="my-agent")

def model() -> Model:
    config = load_agent_config(Path(__file__).parent / ".agent_configs")
    if not (config.instructions or "").strip():
        raise RuntimeError("No baseline instructions loaded from .agent_configs.")
    return configured_model(config)()

@app.activity(Teams.direct, Teams.group, Teams.channel_mention)
@app.responses()
@app.invocations()
async def reply(text: str, model: Model = Depends(model)) -> str:
    return await model.respond(text)

if __name__ == "__main__":
    app.run(host="0.0.0.0", port=8088)

Use HOST=127.0.0.1 for local runs only. Hosted deployments need 0.0.0.0 so platform ingress can reach the process.

SDK pieces

The root package exposes the short public API (Agent, Router, Depends, Model, Message, Teams, and related helpers). The SDK is split by what you are trying to do.

Area	What it is for
protocols	Activity wire models and protocol accessors.
runtime	Agent and router composition, dependency injection, turn context, and dispatch.
hosting	HTTP endpoints, local run policy, credentials, and agentic identity.
messaging	Teams surfaces, Activity routing, replies, cards, entities, invoke helpers, streaming, and connector support.
inference	Model calls and executable tool definitions.
integrations	Foundry toolbox adapters and Graph operations.
building	Scaffolding, readiness checks, and offline protocol testing.
evaluation	Evaluation suite configuration, rubric validation, and azd evaluation commands.
observe	Telemetry, tracing, execution records, queries, and drift checks.
optimizing	Candidate configuration, baseline generation, and optimizer jobs.
finetuning	RFT preparation, submission, and existing job management.
lifecycle	Snapshots, datasets, evidence, acceptance, and promotion records.
delivery	Manifest generation and guarded azd deployment.

What is shipped

Surface	Status
Python SDK	Shipped.
Responses, Activity, and Invocations adapters	Shipped.
FastAPI-style dependency injection and routers	Shipped.
Local protocol test harness	Shipped.
Baseline .agent_configs resolution	Shipped through castia[optimize].
Foundry toolbox MCP specs	Shipped for Responses API server-side MCP execution.
Evaluation suites, observation, optimizer handoff, lifecycle evidence	Shipped as guarded workflows.
SFT, DPO, and reinforcement fine-tuning helpers	Provisional wire acceptance; check before submit.
Rust SDK and Typra generation	Experimental, unpublished; contracts and portable parity tests are in this repo.
Prompty integration, managed agent memory	Not shipped.