ray-train-synthetic

ray-train-synthetic is a skill for Claude Code, Codex from nebius/nebius-physical-ai. It costs 33 tokens per session (811 once invoked), scanned A, original, Apache-2.0.

A guarded reference workflow for running and reviewing a distributed machine-learning training example with Ray Train on CUDA GPUs. It covers checkpoint storage, recovering an optimizer, environment versions, host setup, preflight checks, and teardown.

In plain words
What is it for?
Use it to run or review the specified synthetic Ray Train workload, select GPUs, manage checkpoints, recover training state, and verify the reported metrics.
Why use it?
It documents the boundaries between the training application, cloud host management, storage, and production workflows. The checks help avoid using the wrong storage, incompatible software, or lingering paid resources.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to run or review the specified synthetic Ray Train workload, select GPUs, manage checkpoints, recover training state, and verify the reported metrics.

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Install with agentmods
npx agentmods add skills/nebius/nebius-physical-ai/ray-train-synthetic
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add nebius/nebius-physical-ai --skill ray-train-synthetic
Clone the repo
git clone --depth 1 https://github.com/nebius/nebius-physical-ai

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

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README.md
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Your own site
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Your own site · 80×15
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Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 811 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00033 $0.00811
Opus 5 $0.00016 $0.00405
Sonnet 5 $0.00007 $0.00162
Haiku 4.5 $0.00003 $0.00081

Measured 3d ago against content hash 9e3ad116380c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

ray-train-synthetic scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/tools/ray-train-synthetic/SKILL.md · 65 lines

What it actually says

Native Ray Train reference

Use the reference guide. This is a guarded application example: native Ray Jobs delivers source and owns submission/status/logs/stop; SkyPilot owns the development hosts and service task. It adds no NPA Jobs wrapper, controller, CLI group, image or workflow catalog. Use npa.workflow for production composition beyond this single application.

Read health-preflight, gpu-selection, skypilot-workflows, third-party-eula-preflight, and teardown-and-cost before live operation. Preflight the selected project's exact workload bucket and prefix; do not use a different project's Terraform-state or trajectory bucket as training storage.

The pins are application Ray 2.58.0 / Train V2, Torch 2.13.0+cu130 in the digest-pinned upstream PyTorch image, Rerun 0.31.4 and Pillow 12.3.0. The driver and every new or restarted worker enforce the Torch pin at run time. Keep application Ray separate from SkyPilot's management environment and reserved ports. Pure Python source changes use native Jobs --working-dir; native ABI changes require a compatible prepared environment. There is no model or external dataset download.

Preparation uses the pinned image's root account and requires a fresh owned mode-0700 /opt/npa-ray-train below an /opt without shared write access. Keep its environment, exports, preparation receipt, and application Ray temporary files inside that directory. Existing directories and symlinks fail closed; preserve failed-attempt evidence and use fresh hosting pods rather than clearing or adopting an unknown runtime. The service validates ownership and permissions before it starts and scopes RAY_TMPDIR to this application directory.

Use two B200 hosts with one GPU each for the shipped profile. Require actual rank/world-size, CUDA device and physical-host evidence before calling a result multi-node. SPREAD and a requested GPU count alone are not placement evidence.

Ray Train V2 recovers through the same RunConfig(name, storage_path) and worker get_checkpoint(). Do not use V1 resume_from_checkpoint, restore() or trainer_resources. Every worker must call report equally often; only rank zero uploads checkpoint bytes. Before injected failure, wait for native CheckpointConsistencyMode.COMMITTED, then prove every worker resumed at the next optimizer step with model and momentum state restored.

S3 credentials belong in the private hosting environment on every Ray host. Pass no keys to S3FileSystem itself: its serialization otherwise carries them. Keep credentials out of source delivery, Jobs runtime-env JSON and reports. Store checkpoints with the native Arrow filesystem; upload the final export with its checksum manifest last and require read-after-write verification.

Validate all optimizer steps and scalar values decoded from metrics.rrd against metrics.json using inspect_results.py. Independently run rerun rrd verify and rerun rrd print -vv. After compute teardown, download again from S3 and reload the native model/optimizer checkpoint. Synthetic regression proves training execution and recovery, not robot-policy quality.

npa/.venv/bin/python -m pytest npa/tests/workflows/test_ray_train_synthetic.py -q

The opt-in live suite is npa/tests/e2e/test_ray_train_synthetic_live.py. Its private configuration selects an already-preflighted isolated Ray Jobs endpoint and workload S3 prefix. Cancel exact Jobs before the Sky service task and named development cluster; retain shared infrastructure and verified artifacts.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 65 lines · 33 tokens per session scan A 9e3ad116380c

Subscribe to this mod's changes

ray-train-synthetic is a skill published in the GitHub repository nebius/nebius-physical-ai (29 stars, last pushed today), licensed Apache-2.0. It adds 33 tokens to every session and 811 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-09.

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