Screwed three‑board corner frame by a bimanual robot

A flat U‑shaped corner: three boards, two joints, six screws

Role

The controller of a simulated bimanual robot in a workshop of wooden boards, acting only through a local HTTP command service, with nobody giving movement advice.

Request

Set three boards as a flat U‑shaped corner, every corner inside its outline, and join both overlaps with three separate, non‑collinear screws each; back the drill out, let go, and confirm success once it all settles.

Deliverable

The final physical state, from the engine's last observation: three boards placed and released, six screws installed, both joints rigid and the drill withdrawn. A short summary is saved too; its claims don't count.

What the reward depends on

Every board inside an outline of its own size once settled, after a real lift and release, both joints rigid with three screws each, and the drill withdrawn. One point or none.

Where the requirements are

Stated in the request and one interface document, with the runtime's source open to read; each observation reports the targets and progress. Nothing is hidden: the difficulty is physical control.

A contact‑only physics workshop, read as exact state and driven by typed commands

Interface

A Codex chat subagent running GPT‑6.1 Sol at its default reasoning setting, sending JSON to a local HTTP control server through its shell tools: read the state, send a step or a sequence of velocity segments, and post short progress notes.

Physics

Rigid‑body physics (cannon‑es) in its own headless Edge process at 180 Hz, apart from any viewer. Simulated time advances only during commands and pauses while the agent plans.

The robot

Two seven‑joint manipulators on bases that slide across the floor, each with a palm and five fingers of three joints, with spread and thumb opposition. Motion is rate‑limited and stopped by collisions, so a target isn't always reached.

Grip

No attachment constraint: a hold is opposed, force‑bearing finger contact, so boards, drills and screws can slip, turn or drop while the hand stays closed, and over‑curling can push a board out.

Observations

Exact structured state, not images: board poses, sizes and velocities; drill and screw poses and states; finger angles, contact force and slip; collision and joint‑limit feedback; each target's pose and progress.

The build

A cross rail and two side boards in angled stock cradles, laid flat as a U with the sides over the rail, joined at two overlaps by six screws.

Drill and screws

Graspable drills with no magazine, and screws handled one at a time: pinch a screw, set it on the overlap, align the other hand's drill bit, engage, let go, feed along the axis, then withdraw before any sideways move.

Recording

Every command result and sampled pose is saved; four fixed cameras render review videos afterwards, at simulation speed. The saved observations, not the videos, are the record.

Network

Internet on, for the pinned physics libraries; web tools off by instruction, not by a network sandbox. Nothing the job needs is online.

Limits

One session of 20 minutes of wall time, planning included, plus the scenario's own action and simulation‑time budgets. The request rules out resets, teleporting, direct state changes and earlier trajectories.

One all‑or‑nothing check on the final physical state

Structure

One check, worth one point: the whole build complete. Boards placed, screws installed and each board's worst corner protrusion are reported as diagnostics, never scored.

Placement

Each board must be lifted, released and left to settle with all eight corners inside a target outline of its own size, allowing only a numerical margin. Holding a board in place doesn't count.

Fastening

Every joint rigid, made by three non‑collinear screws driven through the top board into the one below, and every drill withdrawn. Matching the outlines alone doesn't pass.

Who decides

A script reads the final observation and transforms every board's eight corners into its target's frame; it also needs the engine's own success flag for lift, release, settling and any joints. No model judge, and the agent's claims don't count.

A stricter check

This attempt ran under an earlier engine check that accepted boards centimetres off, as its documentation described, and its request lacked the corner rule. It was regraded on the strict check, with no new attempt.

Engine reward

After each action the engine also returns a shaped reward from the boards' distances to their targets, with a bonus on success and a penalty for a lost board; the grader ignores it.

Formula

Reward = 1 if the build is complete, else 0. An untouched scene, a partial build or a missing final state scores 0.

All three boards ended centimetres out, and no screw went in

GPT‑6.1 Sol, the only model tested on the builds, scored 0%. Its three boards came to rest 38.1 to 61.2 mm outside their outlines at the worst corner, and no screw went in before the 20‑minute limit.

Each dot is one attempt; the line marks the median.

One attempt, by GPT‑6.1 Sol at seed 1; no other model has been tested on the ten builds.

Made on 29 October 2026, before the corner rule joined the request, under the engine's earlier check, which its documentation described; regraded the same day on the strict one, with no new attempt.

What the model got wrong

One attempt, by GPT‑6.1 Sol, made under the engine's earlier check and graded on the strict one.

1. Centimetres out. All three boards came to rest outside their outlines, by 61.2, 38.2 and 38.1 mm at the worst corner.

2. No screw driven. Placement never led to a completed fastening cycle, so 0 of 6 screws went in and neither joint was rigid.

3. Out of time. The server stopped the attempt at the 20‑minute limit, after 41 motion commands and 299 simulated seconds.

What an attempt costs

Length

The attempt used its full 20 minutes of wall time, with 41 motion commands and 299 simulated seconds. Model calls, tool calls and tokens weren't recorded; a motion command isn't a model call.

Cost

Not recorded: the attempt ran on a subscription sign‑in, which logs no cost or tokens, so we give no figure.

What you license

With a licence

Revision 2: the frozen runtime with this scenario at seed 1, the request and interface document, the grader and its self‑test, and the attempt's commands, observations, pose trajectory and four review videos, as baseline results.

Format

Runs on Node.js, with the physics in headless Microsoft Edge driven by Playwright, and a Python grader; today on a Windows PC, outside a container. Other packaging on request.

Fresh variants

Other builds and layouts in the same design, on request. They're never published.

Public or not

The AI Agent Trials, our public benchmark, sums up the job and shows each model's score, so hold out fresh variants for evaluation. The files, grader and answer key aren't published.

What we haven't measured, and what's uneven

• One attempt, by one model, at one seed, so we haven't measured how much attempts vary or how other models do.
• This attempt's request lacked the corner rule and its documentation described the earlier, looser check, so it can't show how a model does when told the strict rule.
• No reference solution: no attempt, scripted or by an agent, has completed a build under the strict check, so it isn't shown that one can be; the self‑tests check only the scoring.
• Each outline is its board's own size, so a board must settle almost exactly at its target pose; whether the contact solver allows that hasn't been tested.
• The grader trusts the engine's own flag for lift, release, settling and joints, and checks only the geometry; the lift flag can register for a board grasped in raised stock without upward travel.
• The agent reads exact state and may read the runtime's source, which reveals the thresholds: this tests control from state, not from vision.
• Simplified physics: rigid contacts, simplified fingers and idealised stock fixtures, with no thread cutting or motor torque, so results don't speak to real robots.
• Up to three attempts shared one PC at a time, so wall time may include contention.