FastVideo: Skill for Claude Code

.agents/skills/seed-ssim-references/SKILL.md

seed-ssim-references is a skill for Claude Code, Codex from hao-ai-lab/FastVideo. It costs 146 tokens per session (4,909 once invoked), scanned A, original, Apache-2.0.

A workflow for creating reference files needed by new SSIM tests in FastVideo; SSIM is a measure of visual similarity between generated and reference media.

In plain words
What is it for?
Use it when adding a new video or latent similarity test, to run it on a Modal L40S machine, inspect the output, and upload only the new reference files to Hugging Face.
Why use it?
It generates the missing video or latent reference artifact, downloads it, and pauses for quality checks before upload, preventing unverified test data from being stored.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

This is hao-ai-lab/FastVideo's own configuration. It tells Claude Code and Codex how to work on FastVideo itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything FastVideo configures →

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is ./generated_videos_modal/default.

About the project

FastVideo is a framework for training and running accelerated video-generation models, including real-time inference and post-training workflows. It is for researchers and developers building or deploying diffusion-based systems that generate video.

hao-ai-lab/FastVideo · 4,368 stars · on GitHub · hao-ai-lab.github.io

Reuse

Borrowing it

Nothing to install: this file belongs to hao-ai-lab/FastVideo. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/hao-ai-lab/FastVideo/main/.agents/skills/seed-ssim-references/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/hao-ai-lab/FastVideo

Made for: Claude Code, Codex.

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README.md
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Per session 146 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,909 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00146 $0.04909
Opus 5 $0.00073 $0.02455
Sonnet 5 $0.00029 $0.00982
Haiku 4.5 $0.00015 $0.00491

Measured 11d ago against content hash 3c1111e2d213, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

seed-ssim-references 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 11d 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.

.agents/skills/seed-ssim-references/SKILL.md · 381 lines

How it starts

The opening of the file, as written. The whole thing — 381 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Seed SSIM Reference Artefacts (mp4 or pt)

Purpose

A brand-new SSIM test in fastvideo/tests/ssim/ fails forever until its reference artefacts exist on the HF dataset (FastVideo/ssim-reference-videos). The dataset hosts two kinds of artefacts side-by-side per (model_id, backend, prompt):

  • .mp4 — pixel ground-truth for tests that call run_text_to_video_similarity_test / run_image_to_video_similarity_test in inference_similarity_utils.py. Compared via SSIM.
  • .pt — pre-VAE latent bundle (fp16 full latent + fp32 slice + metadata + slice_spec + format_version) for tests that call run_text_to_latent_similarity_test in latent_similarity_utils.py. Compared via cosine distance on the slice and the full tensor.

This skill:

  1. Detects which artefact type the test produces (pixel vs latent).
  2. Runs the test on Modal's L40S pool to generate the artefacts.
  3. Downloads them to the local repo via modal volume get.
  4. Pauses so the user can verify quality:
    • mp4: visual eyeball in a video player.
    • pt: numerics dump (shape, slice stats, NaN/Inf check, metadata).
  5. Uploads only the new test's files to HF, with a guard that refuses to overwrite anything already present.

The skill is run manually, once per new test. Before invoking it, the user has already sanity-tested the new test locally — it launches VideoGenerator and writes an artefact without crashing (the missing-reference assertion at the end is expected). The skill does not re-test locally; it goes straight to the manual legacy Modal L40S reference-maintenance target. Active CI runs on the Slinky Slurm cluster and only consumes the resulting references.

When to use

  • A new test_*_similarity.py file has been added in fastvideo/tests/ssim/ and the HF dataset has no reference_videos/default/L40S_reference_videos/<model_id>/ subtree for it yet.

When not to use

  • Regular CI runs — once refs exist, pytest fastvideo/tests/ssim/ downloads them automatically.
  • Re-seeding an existing test. That requires --force on the upload step, and is out of scope here; treat as a separate, deliberate operation.

Read the full file on GitHub · 381 lines

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. 11d ago First seen · 381 lines · 146 tokens per session scan A 3c1111e2d213

Subscribe to this mod's changes

seed-ssim-references is a skill published in the GitHub repository hao-ai-lab/FastVideo (4,368 stars, last pushed 2d ago), licensed Apache-2.0. It adds 146 tokens to every session and 4,909 once invoked, about $0.0007 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 2026-08-30.

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