Classes across the sandbox boundary

One concise, runnable file per behaviour, in Python and TypeScript.

Python

Each needs a dev build of the bindings and worker (make dev-py), then:

bash

uv run python examples/classes/class_instance.py

File	Behaviour
`class_instance.py`	Expose a host object with an explicit policy; identity round-trip
`lazy_attrs.py`	Attributes fetched from the host on demand; denial raises `AttributeError`
`sandbox_copy.py`	Sandbox mutations stay on the sandbox copy; the host object is untouched
`convert_value.py`	Transform / wrap values as they cross the boundary (each wrap is retained for the session)
`class_type.py`	Let the sandbox instantiate a host class (`init=True`)
`class_type_members.py`	Class constants and classmethods without instantiation
`sandbox_classes.py`	Classes defined inside Monty; instances return as `MontyClassProxy`
`sandbox_round_trip.py`	A `MontyClassProxy` passed back resolves to the original sandbox object; freed objects raise
`async_methods.py`	`async def` methods awaited from sandbox code via `AsyncMonty`

TypeScript

The examples import @pydantic/monty from this repo's JS crate, so build it (make build-js), install the local link, build the worker binary (cargo build -p monty-runtime, which make build-js does not) and point the workers at it. They run directly under Node 24+ (native type stripping and await using):

bash

cd examples/classes && npm install && cd -
cargo build -p monty-runtime && MONTY_BIN=$PWD/target/debug/monty node examples/classes/class_instance.ts

MONTY_BIN matters when another monty is on PATH: a worker from a different release speaks a different protocol version and the pool reports it as a crash. npx tsc -p examples/classes type-checks them.

File	Behaviour
`class_instance.ts`	Expose a host object with an explicit policy; identity round-trip
`lazy_attrs.ts`	Attributes fetched from the host on demand; denial raises `AttributeError`
`class_type.ts`	Let the sandbox instantiate a host class (`init: true`)
`sandbox_classes.ts`	Classes defined inside Monty; instances return as `MontyClassProxy`
`sandbox_round_trip.ts`	A `MontyClassProxy` passed back resolves to the original sandbox object; freed objects raise