Extension System

The dart_monty extension system lets you expose Dart functions to Python code running in the Monty sandbox. This guide suite covers the system from first principles through production patterns.

Guides

Level	Document	What you will learn
Intro	Host Functions Intro	What host functions are, why they exist, and a 3-line "hello world"
Beginner	Host Functions Beginner	HostFunctionSchema, typed params, validation, error handling, BridgeEvent stream
Intermediate	Host Functions Intermediate	MontyExtension, ExtensionCoordinator, namespaces, lifecycle hooks, introspection, EventLoopExtension
Advanced	Host Functions Advanced	SandboxExtension, child spawning, depth/concurrency limits, production patterns
Middleware	Bridge Middleware	BridgeMiddleware, sealed CallRole, onion chain, grounding, rate limiting, why CompositeExtension was removed

Architecture at a Glance

+--------------------------------------------------+
|  ExtensionCoordinator + MontyExtension                    |  namespace validation,
|  (dart_monty_bridge)                             |  lifecycle, introspection
+--------------------------------------------------+
|  BridgeMiddleware + CallRole                     |  onion-style policy chain
|  (dart_monty_bridge)                             |  (grounding, telemetry, ACL)
+--------------------------------------------------+
|  DefaultMontyBridge + HostFunction               |  dispatch loop, event
|  (dart_monty_bridge)                             |  streaming, arg coercion
+--------------------------------------------------+
|  MontyPlatform (start/resume/run)                |  raw platform interface
|  (dart_monty_platform_interface)                 |
+--------------------------------------------------+
|  MontyFfi / MontyWasm                            |  FFI or WASM backend
|  (dart_monty_ffi / dart_monty_wasm)              |
+--------------------------------------------------+

Most applications work at the top two layers. Start with the Intro guide and progress through the levels as your needs grow.