SDKs

The SDKs embed the same Rust engine that runs in a fleet, so an agent behaves the same in your app and on the platform. They are thin wrappers over one shared core; every SDK passes the conformance suite in spec/conformance.

Language	Package	README	Example
Python	sdks/python (native module, built with maturin; needs Rust)	sdks/python	examples/python-app
Node.js	sdks/node (napi-rs)	sdks/node	examples/node-app
Go	sdks/go (cgo over a static library)	sdks/go	examples/go-app
Rust	the agen-sdk-core and agen-engine crates (the core the other SDKs wrap)	engine	engine/crates/agen-sdk-core/tests

What every SDK offers:

• An agent from code (instructions, model, provider, tools) or from a bundle directory.
• Tools written in the host language; side-effecting unless marked read-only, with the same effect ledger as the fleet.
• Streaming text, cancellation, and an approval callback for ask permissions (default: deny).
• Memory: one agent object is one conversation; a store (sqlite:...) keeps sessions across restarts.
• Models and budgets: fallback models, routing models with cost tiers (per agent and per run), reasoning effort, OpenRouter settings, compaction (contextTokens) and maxTokensPerRun; see Models and providers. A router’s budgetTier applies to deployed agents only (the Hub tracks daily spend).
• With bundle, the bundle’s own settings are used: options passed next to it are refused.

Callbacks (tools, approvals, events) run on one dispatcher thread per agent, in order: return quickly and hand slow work to another thread. Calling run from inside a callback is rejected.