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This guide walks you through a complete Hosted Training run — from setting up your workspace and choosing an environment to launching a run, monitoring progress, and reviewing results.

Prerequisites

Make sure you’ve completed the initial setup:
See Getting Started if you need help with any of these steps.

Step 1: Choose an Environment

You can use an existing environment from the Environments Hub or create your own. For this walkthrough, we’ll use the alphabet-sort environment — a multi-turn game where the model must sort letters into alphabetical order. If you’re new to how environments work, see The Environment Model. Install it:

Step 2: Run a Baseline Evaluation

Before training, evaluate the base model to establish a baseline. This helps you confirm the environment works and understand where the model starts:
A good training environment should have a baseline reward between roughly 10–80%. If the model scores 0% after many attempts, the task is too hard. If it’s already at 80%+, consider harder examples or a different environment.
View the results:

Step 3: Choose a Model

Check which models are available for Hosted Training:
For a first run, we recommend starting with a smaller model to validate your setup quickly: See Models & Pricing for the full list.

Step 4: Create a Training Config

Training runs are configured via a .toml file. Create one in your configs/rl/ directory:
This is a minimal config suitable for a validation run. The key fields are:
  • model — The Hugging Face model ID (must be a supported model)
  • max_steps — Total number of training steps
  • batch_size — Number of rollouts per training batch
  • rollouts_per_example — How many rollouts to generate per dataset example
  • [sampling].max_tokens — Maximum tokens the model can generate per response
  • [[env]].id — Legacy environment selector, usually an Environments Hub ID
Hosted Training also supports Verifiers v1 taskset/harness environment configs in the same outer [[env]] block. The Verifiers v1 equivalent of the environment section above looks like:
Use the legacy id shape for existing Verifiers environments that expose load_environment(**args). Use the Verifiers v1 taskset/harness shape when the environment is packaged as a taskset (task data, controls, rewards, metrics) plus a harness (the program that drives the model). Bare ids such as "alphabet-sort-v1" are resolved by the runtime package; slash-shaped ids such as "team/my-taskset" are resolved through the Environments Hub.

Step 5: Launch the Training Run

Start the run:
You’ll see output confirming the configuration and a link to the dashboard:

Step 6: Monitor the Run

You can monitor your run in two ways: In the terminal — stream logs in real-time:
On the dashboard — open the URL printed when the run started. The dashboard shows reward curves, rubric scores, reward distributions, and individual rollouts. Key metrics to watch:
  • Reward — The overall reward curve should trend upward over time
  • Rubric — Individual rubric component scores
  • Reward Distribution — Should shift from lower to higher values as training progresses

Step 7: Review Results

Once the run completes, you can review the trained model’s performance by running an evaluation with the trained adapter. Trained LoRA adapters can be downloaded from the dashboard. You can also deploy your trained LoRA adapter for live inference — see Deploying LoRA Adapters for Inference for a step-by-step guide. To compare against the baseline, re-run the same evaluation you ran in Step 2 and compare scores.

Putting It All Together

Here’s the complete workflow as a single script:

Run Size Guidelines

Depending on your goals, here are some recommended configurations:

Small Run (Validation)

Use this to verify your environment and config work correctly before committing to a longer run.

Medium Run (Experimentation)

Good for iterating on environment design and hyperparameters.

Large Run (Production)

For serious training with full monitoring and evaluation.

Advanced Configs

Explore all configuration options including multi-env training, evaluation, and checkpointing.

Troubleshooting

Solutions for common issues with Hosted Training runs.