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PolicyClient

Opens a WebSocket to the server for model and reads its metadata. If the server offers a direct route to its GPU container, the client reconnects there and closes the proxied connection.
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str
required
The model ID: "pi05", "pi0" or "groot". It fills {model} in WALLE_URL.
The constructor blocks until the server answers, with no timeout. On a server that is still loading its model, that can take a few minutes. Raises
  • KeyError if WALLE_URL is not set.
  • websockets.exceptions.InvalidStatus, InvalidURI or OSError if the server can’t be reached.

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infer

Sends one observation and waits for the policy’s actions.
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dict
required
Camera frames, state, prompt and any request options. The keys depend on the model. See Observations.
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np.ndarray | dict[str, np.ndarray]
π0 and π0.5 return a float32 array of shape (action_horizon, action_dim), for example (50, 32). GR00T returns a dict of float32 arrays, one per action group, each of shape (1, action_horizon, k).
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dict
If the server rejects the observation, infer returns {"type": "error", "message": str} and does not raise. The connection stays open, so you can fix the observation and call again. Check for this before executing actions. See Troubleshooting.
The returned arrays are read-only views of the received bytes. Call .copy() on one if you need to modify it in place.

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reset

Starts the next observation fresh, as a new episode. It clears every session on this connection. Call it between episodes. See Episodes and reset.

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get_server_metadata

Returns the settings the server sent on connect. It makes no network call.
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int
Actions per chunk.
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list[int]
[height, width] the server resizes frames to.
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bool
Whether observations should carry a session_id.
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int
π0 and π0.5 only. Width of each action.
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int
π0 and π0.5 only. Maximum cameras per observation.
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str
π0 and π0.5 only. "joint_position".
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list[str]
GR00T only. Keys of the returned action dict.
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str
GR00T only. The robot embodiment the server runs.
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str
Present when the server offers a direct route. The client uses it automatically.

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close

Closes the connection. Any call after close() raises websockets.exceptions.ConnectionClosed.

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Environment variables

relay reads these from the environment, or from a .env file in the working directory or any parent directory. Variables already set in the environment take precedence.