Y Combinator · Published 2026-09-26

Robot-Use Agents: Why General-Purpose Models May Win in Robotics

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Summary

Overview

  • Speaker: Ankit Gupta
  • Channel: Y Combinator
  • Main topic: Robot-use agents and the convergence of general-purpose language models with robotics control
  • Purpose: To analyze the transition of general-purpose LLMs and vision-language models into robotic control agents and discuss the implications for robotics startups. In this YC Decoded episode, Ankit Gupta, Francois Chaubard, and founders from Waddle Labs (Hanming Ye, Vincent Song) and Robocurve (Jay Chooi) discuss the rise of robot-use agents. They examine how large language and vision-language models (like RT-2 and Astra) generalize to robot control through pre-training on web data, code-as-policy methods, data transfer, and the platonic representation hypothesis.

Topic Map

The Rise of Robot-Use Agents

  • Explanation: Introduction of LLMs acting as puppeteers of robot bodies, enabling general-purpose models to control robots across diverse domains.
  • Key claims:
    • LLMs are increasingly tested as robot-use agents.
    • General-purpose models make different robots more capable.
    • Recent viral papers and projects show robots writing code and executing tasks in minutes.
  • Examples:
    • Waddle Labs using Claude Code for robots.
    • GPT-4 Astra scoring 95% on robot control tasks.
  • Terminology:
    • robot-use agents
    • spatial intelligence
    • computational agents
  • Why it matters: It signals a shift from specialized robotics software to general-purpose AI models driving robotic hardware.

Language Models to Robotic Control: RT-2 and Code as Policies

  • Explanation: Discussion on early transfer techniques between language models and robot control, covering RT-2 and Code as Policies.
  • Key claims:
    • RT-2 fine-tunes vision-language models on robotic trajectory data and web data.
    • Code as Policies allows LLMs to write Python code combining perception and control primitives.
    • Models benefit from massive pre-training on internet text and images.
  • Examples:
    • Google's RT-2 paper mapping web knowledge to robotic control.
    • Code as Policies using Python function libraries for robot execution.
  • Terminology:
    • RT-2
    • VLA
    • Code as Policies
    • end-to-end control
  • Why it matters: Pre-training on non-robotics web data significantly boosts robotic task performance and generalization.

Platonic Representation Hypothesis & Future of Robotics

  • Explanation: Examining whether strong language models naturally share strong representations with physical world models.
  • Key claims:
    • Strong language models converge on consistent mappings of the world as they train on larger datasets.
    • Vision capabilities in models like Astra leverage massive pre-training on computer-use and CAD data.
    • General-purpose robots capable of handling unseen tasks are approaching rapidly.
  • Examples:
    • Astra controlling robot arms using camera inputs and tool calls.
    • DreamCoder and Bayesian program learning comparisons.
  • Terminology:
    • platonic representation hypothesis
    • transduction vs program induction
    • spatial intelligence
  • Why it matters: It suggests that advancing general intelligence models will automatically solve robotic control without needing purely dedicated robot datasets.

Key Points

Pre-training transfer from web data

  • Explanation: Models trained on internet text, images, and code develop spatial and logical reasoning that transfers effectively to robotic control.
  • Evidence: RT-2 and Astra benchmarks showing superior performance over models trained solely on robot data.
  • Practical implication: Robotics companies should leverage foundation models rather than building robotics-only models from scratch.

Tool-use versus end-to-end control

  • Explanation: Distinction between using LLMs to write code/make tool calls versus direct end-to-end action outputs.
  • Evidence: Code as Policies writing Python functions versus VLA end-to-end pose outputs.
  • Practical implication: Choosing between code generation and direct control depends on task latency and repeatability.

Frameworks, Models & Processes

Code as Policies

  • How it works: LLMs are given perception API functions and write executable Python code to control robots and perform complex tasks.
  • Components:
    • Perception APIs
    • Control primitives
    • LLM code generator
  • When to use: When tasks require repetitive execution, logic structuring, and low-latency safety bounds.

Examples & Case Studies

Astra controlling robot arms to pick up an apple block and place it in a bowl.

  • Illustrates: Vision-language models utilizing camera feeds and tool calls to manipulate physical objects.
  • Lesson: Pre-trained vision capabilities significantly enhance robotic spatial manipulation.

Actionable Takeaways

  • Immediate:
    • Apply to YC at ycombinator.com/apply.
    • Explore integrating vision-language models into robotic control pipelines.
  • Strategic:
    • General-purpose intelligence models will redefine robotics capabilities.
    • Combining web data pre-training with robotic task fine-tuning yields superior generalization.
  • Questions to investigate:
    • How do we solve the latency bottleneck for real-time robotic control?
    • What is the optimal boundary between weight-space learning and symbolic code execution?

Claims Worth Verifying

  • GPT-6 Astra scored 95% on robot control tasks, outperforming Fable 5.1. (benchmark claim)
  • Model latency in VLA approaches improves by 2x per month. (technical trend claim)

Notable Quotes

"This year we are going to see many LLMs being tested as robot-use agents." (at 0:13) "If you give the AI model more autonomy and you if you unshackle it a bit more... it can actually do a lot of things that we fine-tune it to do." (at 6:55)

Compressed Summary

  • LLMs are transitioning from software assistants to robot-use controllers.
  • Pre-training on internet data, images, and code improves robotic spatial intelligence.
  • Code-as-policy and vision-language-action models are bridging the digital-physical divide.
  • Keywords: robotics, llms, agents, rt2, vision-language
  • Core insight: General-purpose language and vision models pre-trained on internet data are rapidly outperforming specialized robotics models by leveraging transferred spatial and logical reasoning.

Core insights

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No core insights.

Deep dives

4

Pretraining transfer to physical control: how far does the platonic representation hypothesis actually get you?

Research question

To what degree do representations learned from internet text/image/computer-use data transfer to closed-loop physical manipulation, and at what point does robot-specific trajectory data become the binding constraint rather than a nice-to-have?

Why

If representation convergence is real, robotics startups should stop investing in bespoke policy architectures and start investing in tool interfaces, data flywheels and hardware; if it is not real, they will be outcompeted by teams that kept collecting robot data. The capital allocation decision hinges on this.

Strong language models converge on consistent mappings of the world as they train on larger datasets.
Open source video
It suggests that advancing general intelligence models will automatically solve robotic control without needing purely dedicated robot datasets.
Open source video
Vision capabilities in models like Astra leverage massive pre-training on computer-use and CAD data.
Open source video
Source video

Code-as-Policies vs end-to-end transduction: reliability, inspectability and failure containment

Research question

For a fixed task suite, do LLM-generated Python programs composed from a curated perception/control primitive library outperform end-to-end VLA policies on success rate, recovery-after-failure, and auditability, and where does each class fail?

Why

This is the concrete engineering fork every robot-use agent team must pick. Program induction gives you inspectable artifacts, retry semantics and unit-testable skills; transduction gives you latency and gradient-level smoothness but opaque failures. The tradeoff is empirical, not philosophical.

Code as Policies allows LLMs to write Python code combining perception and control primitives.
Open source video
Code as Policies using Python function libraries for robot execution.
Open source video
DreamCoder and Bayesian program learning comparisons.
Open source video
Source video

What '95% on robot control tasks' actually measures

Research question

What is the task distribution, horizon length, reset protocol and physical-variation budget behind headline robot-use agent scores, and how quickly does success rate decay under pose, lighting, object-instance and instruction-perturbation shift?

Why

Headline numbers drive both funding and procurement decisions in robotics, yet the field lacks a shared, adversarial benchmark. Without one, 'general-purpose models make different robots more capable' stays an anecdote and teams optimize against the wrong signal.

GPT-4 Astra scoring 95% on robot control tasks.
Open source video
Astra controlling robot arms using camera inputs and tool calls.
Open source video
Recent viral papers and projects show robots writing code and executing tasks in minutes.
Open source video
Source video

Contribution accounting in the data mixture: web vs. computer-use/CAD vs. robot trajectories

Research question

Given a fixed compute budget, what is the marginal task-performance contribution of each pretraining data source (web text/images, computer-use traces, CAD, robot trajectories) for a robot-use agent, and does the optimal mixture shift with task horizon?

Why

'Models benefit from massive pre-training on internet text and images' is widely repeated but rarely ablated. A contribution curve would tell teams exactly which data to buy, scrape or generate, and would make or break the case for expensive teleoperation data collection.

RT-2 fine-tunes vision-language models on robotic trajectory data and web data.
Open source video
Models benefit from massive pre-training on internet text and images.
Open source video
Google's RT-2 paper mapping web knowledge to robotic control.
Open source video
Source video

Article ideas

4

Your Robot Stack Is One Prompt Away From Being Commoditized

As general-purpose models absorb robotic control, the durable moats in robotics shift decisively away from policy architectures and toward physical hardware reliability, proprietary task data flywheels, safety certification and embodied deployment logistics — teams that keep building bespoke control software are defending the wrong layer.

Angle

Strategic/economic argument aimed at robotics founders, framed as 'which layer are you actually defending?' rather than a capability explainer.

Source video

Code-as-Policies Is the Bridge, Not the Destination — And That's Good News

Program-induction style control (LLM writes code over a curated primitive library) will dominate near-term deployments not because it is more general, but because it is inspectable, retryable and testable, while end-to-end policies remain hard to debug and certify; the honest framing is that code-as-policy is scaffolding that will be gradually eaten from both ends by better VLAs and better tool ecosystems.

Angle

Engineering-honest counterpoint to the end-to-end hype cycle, with a concrete argument about verification, not accuracy.

Source video

Benchmarks Are the Bottleneck, Not Models: A Critique of Robot-Use Agent Evaluation

Headline success rates for robot-use agents are near-meaningless without a published task distribution and a distribution-shift decay curve; the field's real constraint is that we cannot distinguish genuine generalization from benchmark-fitted competence, and fixing evaluation would accelerate deployment more than another scaling run.

Angle

Methodological critique plus a concrete 'what a credible benchmark must report' checklist.

Source video

The Platonic Representation Hypothesis Is a Bet, Not a Result

Representation convergence across modalities is an attractive and partially supported conjecture, but treating it as established leads teams to under-invest in the physical grounding and spatial reasoning that tool-using agents still lack; the falsifiable version of the claim — that robot-trajectory data has diminishing marginal value as general pretraining scales — should be tested directly rather than assumed.

Angle

Skeptical research essay that separates testable predictions from narrative appeal.

Source video

Project ideas

4

ShiftBench: A Distribution-Shift Eval for Robot-Use Agents

beyond-evals

Reported success rates for robot-use agents collapse by a large margin (target: >40 percentage points) when evaluated on systematic pose, lighting, object-instance and instruction-perturbation shifts, relative to the base task distribution used in published demos.

Proof of concept

Stand up a small tabletop manipulation suite (pick/place/stack/open) with a scripted perturbation generator over four axes; run it against at least two agent configurations (code-as-policy over a primitive library, and an end-to-end VLA) and publish a full decay curve per axis plus cost per successful episode.

Measurement

Success rate per perturbation axis and severity bucket, degradation slope from base distribution, failure-mode taxonomy (perception error vs plan error vs execution error), and cost-per-success.

Source video

Capability-Scoped Tool Gateway for Robot-Use Agents

gatehouse

Wrapping robot control primitives behind a typed, capability-scoped tool interface (explicit preconditions, effect annotations, velocity/force/joint limits) reduces unsafe-action and unrecoverable-error rates substantially while costing only a small drop in task success rate versus free-form code generation.

Proof of concept

Build a gateway that validates LLM-generated tool calls against a declared capability profile and refuses or rewrites calls violating preconditions; A/B it in simulation against a baseline agent that writes unrestricted Python against the same primitive library.

Measurement

Unsafe-action rate per 100 episodes, unrecoverable-error rate, task success delta versus unrestricted baseline, and human approval count required per task.

Source video

Data-Mixture Ablation for Embodied Agents (DIME)

movement-lab

For short-horizon manipulation tasks, marginal returns to additional robot trajectory data diminish sharply once a base of computer-use/CAD/web pretraining is present, whereas for long-horizon multi-step tasks the trajectory-data term dominates.

Proof of concept

Train or fine-tune matched small-scale models on controlled mixtures of (a) web text/image, (b) computer-use traces, (c) CAD, (d) robot trajectories, and evaluate on a fixed short-horizon and long-horizon task split with identical compute.

Measurement

Per-source marginal success-rate contribution curves; interaction between mixture ratio and task horizon; break-even point where extra trajectory hours stop paying for themselves.

Source video

Falsification Harness for the Platonic Representation Claim

new

If representations converge across modalities as scale increases, then linear probes trained on a frozen general-purpose model's internal representation should predict physical quantities (relative depth, contact state, object affordance) with accuracy that improves monotonically with model scale — if this fails, the practical case for skipping robot-specific data collection weakens materially.

Proof of concept

Extract frozen representations from a scale ladder of publicly available general-purpose models, fit identical linear probes for a fixed set of physical predicates from a shared robot perception dataset, and plot probe accuracy against model scale and pretraining-data composition.

Measurement

Probe accuracy vs. model scale and vs. pretraining-modality mix; slope of improvement; correlation between probe accuracy and downstream task success on a held-out manipulation set.

Source video

Architectural implications

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No architectural implications.

Tradeoffs and failure modes

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No tradeoffs or failure modes.

Open questions

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No open questions.

Key claims

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No key claims.

Connections

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No connections.