MetaWorld MT50 direct-control protocol

Status: development adapter; native parity and full schedules remain pending. Default protocol ID: metaworld-mt50-3.1.1/rgb480-corner2-rot180/control400/fast-v2. The explicit image_orientation="native" compatibility track retains metaworld-mt50-3.1.1/rgb480-corner2/control400/fast-v1. The server is an independent process; its credentials and native handles are evaluator-private. See the SIM server protocol.

Native identity and task selection

The native implementation is the public metaworld==3.1.1 distribution, with MuJoCo 3.3.0, Gymnasium 1.3.0 and NumPy 1.24.4. The checked-in package pin records SHA-256 and size for all 440 shipped package files (325 bundled assets), checked against installed wheel RECORD entries and actual bytes. Its canonical file-inventory SHA-256 is 768366070ab463f23539105601f530461ffb0523946f889749295a0a2c367454. This is a distribution-content pin, not an inferred Git commit. Runtime verification rejects different package bytes, versions, import shadowing or unexpected native files before constructing an environment. The pin does not attest GPU drivers, loaded memory or the full transitive dependency graph.

The server also explicitly pins packaging==26.2, an import-time dependency of Gymnasium's optional MuJoCo renderer. Environment setup verifies the native import path as well as package metadata; neither check constructs an episode.

MT50 contains 50 task families. task_catalog.json freezes their native order and names. The retained StarVLA evaluator supplies language instructions and four difficulty labels: easy 28, medium 11, hard 6 and very_hard 5. Those labels are a retained integration taxonomy, not a native MetaWorld difficulty standard. Native version 3.1.1 renamed five old labels:

Archived alias	Canonical native name
`nut-assembly-v3`	`assembly-v3`
`nut-disassemble-v3`	`disassemble-v3`
`door-v3`	`door-open-v3`
`peg-insertion-side-v3`	`peg-insert-side-v3`
`sweep-into-goal-v3`	`sweep-into-v3`

The selector accepts these aliases, normalizes them before scheduling and rejects duplicates. Every recorded task uses its canonical name. A fast schedule contains exactly one episode per explicitly selected task, in the declared order, with an explicit seed. The example chooses reach-v3 and seed 4042. No task is substituted or retried after an outcome. A new server output directory is not permission to repeat a task.

The native constructor generates a pool of 50 goal/reset configurations per task family. These are internal randomized native tasks, not 50 scored attempts or a declared full schedule. Each selected fast task constructs a fresh seeded MT50 and evaluates the first native reset for that environment. This independent fresh-task construction differs from carrying one vector environment through a multi-episode aggregate; do not claim full native equivalence.

full is rejected. The historical StarVLA example used 10 episodes per task, seed 4042 and 400 controls. That historical 500-episode matrix and its macro mean over four bucket success rates are not implemented or validated as a full protocol here. No generic harness aggregate replaces that legacy weighting.

Reset and setup

Adapter construction, schedule inspection, describe and open create no native environment. One claimed reset performs:

Verify source/dependency pins and seed NumPy with the recorded seed.
Call native gym.make_vec("Meta-World/MT50", vector_strategy="sync", seed=seed, render_mode="rgb_array", camera_name="corner2", width=480, height=480). This native constructor internally instantiates environments and performs its own goal-generation resets. They are setup, not model actions; native internal setup physics is not counted as agent interaction.
Select the canonical task index. Check action bounds, native timestep, frame skip, action scaling and native horizon.
Call the selected native wrapper's reset(seed=seed). Native RandomTaskSelectWrapper selects its goal before forwarding the reset; the underlying SawyerXYZEnv.reset documents that the seed argument is ignored, while construction already called the native seed() method. Preserve that ordering, rather than reseeding or sampling a goal with custom code.
Execute exactly one native zero action [0,0,0,0] for stabilization, as in the retained evaluator. Then deliver the first public image at control step 0.

The archived evaluator optionally calls iterate_goal_position before reset. Neither selected wrapper nor unwrapped base exposes that method in this pin; the adapter records goal_iteration_method: null. An unexpected callable is version drift and fails visibly, rather than changing goal selection. Native setup errors are not swallowed. Success/termination during stabilization is an initialization error, not a model success.

The adapter owns and closes all 50 native vector environments, not only the selected camera. An uncertain/failed control or render poisons further actions. Cleanup failures remain visible and prevent a clean-close claim.

Public observation

Each decision receives the task instruction and current corner2 frame: 480×480 RGB uint8, no crop, resize, overlay or depth. The orientation is fixed before a schedule starts and is part of the protocol identity:

`image_orientation`	Public full-frame pixels	Protocol suffix
`rot180` (default)	Native RGB rotated exactly 180 degrees	`corner2-rot180/control400/fast-v2`
`native`	Native RGB without any additional transform	`corner2/control400/fast-v1`

The pinned native corner2 camera produces an upside-down view in the inspected headless render. Gymnasium already performs its own documented vertical framebuffer correction; the additional deterministic 180-degree rotation is a benchmark-owned camera-view convention, not a renderer patch. It reverses both image axes, preserves every pixel and channel, and is applied identically to policy observations, recorded PNGs and videos. Provenance records the selected orientation and exact transform. Existing native-orientation evidence is not rewritten or relabelled; compare only matching observation tracks.

The archived VLA bridge also rotated 180 degrees, then center-cropped to two-thirds and resized to 224×224, with a comment requiring training-pipeline matching. This protocol reuses only the deterministic full-frame orientation convention, not that model-specific crop/resize chain. Images are copied to detach native backing buffers. A malformed image is an error, not permission to guess a transform or render another frame.

Native state includes privileged object and goal positions. The adapter drops it entirely: no 39-D state, proprioception, oracle success, reward, object/target pose, native info dictionary, task sampling state or camera calibration reaches the policy. Policies may retain previously delivered images/actions, but cannot query the simulator or request extra images between scheduled decisions.

Direct native actions

The model returns [delta_x, delta_y, delta_z, gripper_effort], four finite real numbers each in [-1,1]. Booleans, wrong sizes, non-finite or out-of-range values are rejected before native execution; no clipping, gripper binarization or fallback action is added by the adapter.

Native set_xyz_action moves the mocap target by 0.01 × [dx,dy,dz] metres in world XYZ, clipping the target to the native task's workspace. The native mocap quaternion is fixed to [1,0,1,0]; there is no model rotation command. The final scalar supplies native paired actuator controls [g,-g]: positive closes, negative opens. This is a native low-level controller, not task planning or a learned action proposal. One selected action calls native step exactly once: five physics ticks of 0.0025 seconds, hence 80 control Hz.

Limits and native scoring

Quantity	Protocol
Underlying native horizon	500 native controls, unchanged
Maximum model-selected controls	400
Setup control	1 no-op, recorded separately
Maximum raw controls in this track	401, excluding native constructor/reset internals
Example runner mode	`horizon`
Example maximum policy calls	200, including stop/error calls
Example maximum executed chunk prefix	5 explicit controls per decision

The first native end, explicit policy stop, error or exhausted limit ends the attempt. A 200-call cap is not a requirement to make 200 decisions or grant 1000 controls. Extending the native/adapter horizon needs a separate protocol; the current selector does not support a decision-primary 1000-control track.

info["success"] == 1 returned by the native step is authoritative. The retained evaluator ends at the first success; this adapter maps it to termination without calling an additional task predicate. Native termination/truncation is also retained. At 400 unsuccessful model controls the adapter truncates. It does not infer completion from pixels, language or a generic stop response. Native reward is recorded evaluator-side, but is never given to the policy.

Record policy calls, executed action decisions, controls, setup controls and derived policy physics ticks separately. A stop response uses one policy call but no native control. Interrupted native calls may have uncertain execution; native action-start/end records are evidence, not permission to retry.

Evidence and acceptance

Store source and runtime pin receipts, seed/task schedule, the exact action and observation contracts, native outcome/error, native action events, every reset/ control image, PNG hashes and a camera-labelled decodable MP4. Frames are recorded after stabilization and after every successful native control. Video uses 80 fps to preserve native control timing; model deliberation wall time is not simulator time. Usage/provider identity remains unknown if not recorded.

Results belong under AgentPolicies/<profile>/results/metaworld/. Do not write case diaries or model strategy constraints into this benchmark's protocol. Shared record audits are not proof of native execution, source-memory attestation, native full scores or model identity.

The dependency-light checks use fake native environments only. Before capability scoring, independently review and validate native reset/render/action/video via the adapter/server. Native parity still requires fixed-policy checks spanning each retained difficulty bucket and comparison to the pinned evaluator; no completed parity claim is implied by this development entrypoint.