feat(training): train with TRL on a bundle served as an OpenEnv env

AGENTS.md

@@ -112,7 +112,8 @@ and deserialized through a registry.
 | `config/` | The `Config` singleton (`get_config`, `configure`, `reset_config`) in `config/runtime.py`, file discovery in `config/loader.py`, and `load_impl`, which resolves `module:Class` pointers. `agent_env.store` re-exports the config names for compatibility. |
 | `providers/` | `providers/sandbox_providers/` holds the sandbox providers `local`, `modal`, `modal_vm`, `e2b`, `sail_vm` (the `sail` extra), `smol_vm` (the `smol` extra), `tensorlake` (the `tensorlake` extra), `tenki` (the `tenki` extra), `vercel` (the `vercel` extra), `boxd` (the `boxd` extra), `daytona` (the `daytona` extra); `[sandbox] default` and `agent_default` accept a comma-separated fallback chain, whose deploys skip a provider that can't run them. A sandbox provider declares what it runs (`ON_THIS_MACHINE`, and for VMs on this machine the address their requests to it arrive at, `REACHES_HOST_AT`; `CONTAINER_ACCEPTS`, `PRIVATE_NETWORK`; `SUPPORTED_SANDBOX_MODES`, derived from whether it implements `create_sandbox` and `create_vm`; and `SANDBOX_ACCEPTS`, the images an agent's sandbox runs, which defaults to those a VM loads when it implements `create_vm` and to `CONTAINER_ACCEPTS` otherwise, so only a provider that implements `create_vm` yet gives an agent a container, like the local one, declares it), each sandbox carries the `platform` of the images it runs (linux/amd64 unless its provider sets another when it creates it; None, any, unchecked, for a local sandbox), and code outside `providers/sandbox_providers/` reads those, never which provider it has. `providers/env_providers/` holds the environment providers: `EnvironmentProvider` (an env's containers and state store), `EnvironmentGatewayProvider` (`gateway`, an env's default), which renders a docker-compose for the gateway and its MCP servers inside the sandbox, and `EnvironmentServerProvider` (`server`), one MCP server in its own container with no gateway in front and no state store; `providers/env_state/` holds env-state providers (`local_postgres` built in). |
 | `a2a_agent/` | The `A2AAgent` entity (`a2a_agent`), its stores and the validator steps. The protocol package provides the agent-side framework. |
-| `openenv/` | `build_app(bundle)`: the [OpenEnv](https://github.com/openenv/OpenEnv) server for a bundle's tasks, each session playing one episode through the Episode API, with the envs' MCP tools, an added `end_turn` tool and the task's verifier score as the reward. It prepares bundles as `agent-env run` does (`prepare_bundle(played=True)`, without the agent the client plays) and keeps namespace routing on for the app's life. `openenv` comes with the `openenv` extra, a floor with no cap, and this package is the only one that imports it. |
+| `openenv/` | `build_app(bundle)`: the [OpenEnv](https://github.com/openenv/OpenEnv) server for a bundle's tasks, each session playing one episode through the Episode API, with the envs' MCP tools, an added `end_turn` tool and the task's verifier score as the reward. It prepares bundles as `agent-env run` does (`prepare_bundle(played=True)`, without the agent the client plays) and keeps namespace routing on for the app's life. `openenv` comes with the `openenv` extra, a floor with no cap; this package and `training/trl.py` are the only ones that import it. Each task's description in the Task API names its `toolset` (the played agent's envs, role, and whether it gets `bash`). |
+| `training/` | One module per outside trainer, each behind its own extra, and `_tools.py`, which turns an env's tools into typed, documented Python methods from their JSON Schema, as transformers' `get_json_schema` reads them. `trl.py` (`trl` extra): `AgentEnv(url)` over a server `openenv/` makes, with `dataset` (a row per task) and `factory` (TRL's `environment_factory`: a generated class per toolset whose methods are the tools, a background `reset` and an owned `get_reward`); `AgentEnv.local(bundle)` serves the bundle in process. |
 | `runner/` | The `[runner]` seam: `Runner.submit()` returns a `RunHandle` (`run_id`, `instance_id`) before the run starts; `LocalRunner` is built in. `runner/store.py` is the run index every runner writes and the explorer reads. |
 | `bundle/` | A bundle is a folder of entities (`envs/`, `agents/`, `artifacts/`, `skills/`, `tasks/<name>.json`, `evals/<name>.toml`) that runs without a registry: `agent-env run` plans it, writes it into the `@local` namespace (reusing each version whose inputs haven't changed) and runs its evals or tasks; `agent-env bundle init` writes a stored task or eval as one, with every env, agent and artifact it uses in its own folder (each image as its build context, pruned to what its Dockerfile reads and pinned to the Python and npm versions of the stored image) so it runs with no store. |
 | `eval/` | `Eval` (`eval`), a versioned list of task references, and its store. |