How it works
For people and for agents. The same five steps cover robots for simulation, game props and audio. Agents can read the flow as plain text at /llms.txt. What is live for robots, with its evidence, and what NIUA does not do are below the steps.
How a file your agent built becomes a signed pass, in five steps. For developers and for the agents they run.
01 Connect your agent
claude mcp add --transport http niua https://mcp.ohao.tech/mcp02 Check a robot against a contract
niua-runner check arm.zip --contract urdf.sim-ready@103 Anyone re-checks the receipt ("valid": true)
curl https://api.ohao.tech/api/v1/receipts/$RECEIPT_IDFor agents: llms.txt · OpenAPI · example-session.json
01
NIUA is a hosted MCP server. Sign in on first use; the agent gets the gate tools.
claude mcp add --transport http niua https://mcp.ohao.tech/mcpCursor, Codex, other MCP clients, or plain REST: connect another agent.
02
A contract is versioned JSON that says what done means for one kind of file. Use a built-in or write your own.
Robots and motion: simulation only, no hardware tested. Agents read the same list as JSON: /api/v1/contracts/builtin.
03
A robot description for a simulator, Blender, a DAW, an engine: NIUA does not model for it. The agent uploads the exported file (create_upload, finalize_upload) and checks it.
check_artifact {
"key": "<asset_key from finalize_upload>",
"contract": "urdf.sim-ready@1"
}Same check over REST:
curl -X POST https://api.ohao.tech/api/v1/check \
-H "Authorization: Bearer $NIUA_API_KEY" \
-H "Content-Type: application/json" \
-d '{"artifact": {"key": "<r2_key from /api/v1/upload>"}, "contract": "urdf.sim-ready@1"}'04
Every failure carries the rule, where it broke, what was expected, what was found, and the fix. The agent repairs the file in its tool and checks again. Example response:
05
The receipt binds this exact file hash to this exact contract and checker version. Verify it against the public key, online or offline.
# Anyone can verify a receipt. No key needed.
curl https://api.ohao.tech/api/v1/receipts/<receipt_id>
# -> { "receipt": { "verdict": "pass", "artifact_sha256": "...", "signature": "..." }, "valid": true }
# Or offline: Ed25519 public keys (JWKS), matched on the receipt's key_id
curl https://api.ohao.tech/.well-known/niua-receipt-keys.jsonRobotics, sim-ready · live
Each claim opens to its evidence: a demo you can run, the file we used, and a signed receipt you can verify. Simulation only, no hardware tested
simulation only, no hardware tested
NIUA reads a robot file (URDF) against its robot checklist, urdf.sim-ready@1: every part attached in one chain, a real weight on every moving part, a collision shape on every visible part, joint limits the right way round, 3D files that exist, sizes in meters, not millimeters. Each failure names the part, what was expected, what was found and the fix.
simulation only, no hardware tested
We broke our arm 8 ways, one break per copy, and ran every copy through NIUA and two open-source tools. Those tools answer a different question (does the file load?), so they let most breaks through.
Broken copies flagged. Measured 2026-10-15. 13 URDF fixtures from our own desk arm (5 good, 8 broken). Gate: urdf.sim-ready@1. yourdfpy 0.0.60: URDF.load with meshes, then validate(). MuJoCo 3.16.0: MjModel.from_xml_path. Flagged means rejected or failed to load. result.json
simulation only, no hardware tested
Claude Code read the failures NIUA named, edited the robot file (every guessed value marked as a guess) and checked again until it passed. The MuJoCo simulator refused the original file and loads the fixed one.
Measured 2026-10-15. tools/auto-sim/run_auto_sim.mjs against production. MuJoCo 3.16.0 compiles each file, then runs 2 s under gravity from a bent pose with no actuation and checks the state stays finite. run.json
simulation only, no hardware tested
A real NVIDIA Unitree G1 humanoid clip passes motion.g1-safe@1 in a MuJoCo physics replay, run on CPU: every joint inside its range and speed limit, feet on the floor without sliding, upright the whole time. Four mistakes we planted were fixed first, each from a failure NIUA named.
Measured 2026-10-15. tools/g1-motion/record_production.mjs: the production gate checked the published clips; MuJoCo 3.16.0, Menagerie unitree_g1, timestep 0.002 s, joint PD kp 500 kv 10.32, root unactuated, sampled at 50 Hz. Source: the first 3.5 s of NVIDIA GR00T-WholeBodyControl macarena_001__A545. production.json
NIUA has no robot hardware. Every robot check and run on this site happens in software: the gate on our servers and the simulation in MuJoCo. Nothing here was tested on a physical robot.
A pass means the file is well formed for a simulator. It does not mean a physical robot would behave the same, and NIUA never runs a policy on hardware.
Mass, inertia and joint limits are checked for being present and physically possible, not for matching a physical robot. The auto-sim run checks that a model loads and stays finite, nothing more.
The world-models track is planned. No contract, check or receipt exists for it today.
The robot numbers on this site come from our own arm and test fixtures, each one linked. They are not customer results.
Use ohao.tech
Claude, Codex, Cursor or any MCP client. Your agent calls check_artifact after every export and keeps the receipt.
claude mcp add --transport http niua https://mcp.ohao.tech/mcpSelf-host
The same checker and contracts inside your network, with receipts signed by your own key: one gateway container, Postgres and S3-compatible storage.