FastVideo: Skill for Claude Code

.agents/skills/env-var-conventions/SKILL.md

env-var-conventions is a skill for Claude Code, Codex from hao-ai-lab/FastVideo. It costs 64 tokens per session (865 once invoked), scanned A, original, Apache-2.0.

A project-specific guide for adding, reading, renaming, or removing environment variables in FastVideo. Environment variables are named settings supplied outside the program, often for deployment configuration.

In plain words
What is it for?
Use it when changing FastVideo environment variables, deciding whether a setting belongs there or as a command-line argument, or fixing the related policy test.
Why use it?
It keeps these settings typed, documented, and consistent with the project's policy and automated checks.

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 →

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 · 4,758 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/env-var-conventions/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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Per session 64 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 865 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 $0.00064 $0.00865
Opus 5.5 $0.00026 $0.00346
Sonnet 5.5 $0.00013 $0.00173
Haiku 4.5 $0.00006 $0.00086

Measured 29d ago against content hash e3ceeb085cc8, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

env-var-conventions 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 29d 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/env-var-conventions/SKILL.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Environment Variable Conventions

Purpose

FastVideo registers its environment variables as typed fields in fastvideo/envs.py. The policy that governs them is docs/contributing/env_vars.md, and the contract test fastvideo/tests/contract/test_env_policy.py enforces the policy in the unit CI lane. This skill routes an environment-variable change through that policy. The policy doc is the single source of the rules; read it instead of relying on a summary here.

Prerequisites

  • Read docs/contributing/env_vars.md in full.
  • Decide whether the setting belongs in an environment variable or an argument (rule 5 in the policy doc). Settings that users change per deployment are arguments; add them through fastvideo/fastvideo_args.py instead.

Inputs

Parameter Required Description
change Yes Add, read, rename, or remove a variable, or change the policy.
variable Yes The variable name, with the FASTVIDEO_ prefix.

Steps

  1. Declare or edit the variable in fastvideo/envs.py.
    • Pick the field type and category that the policy doc lists.
    • Write a description that states what the variable does and its units.
    • To rename, keep the old name in deprecated_names. To remove, add the name to DEPRECATED_VARIABLES. Update the uses in examples/, scripts/, docs/, apps/, and the tests.
  2. Read the variable with envs.NAME.get() inside a function.
    • In tests, change the value with envs.NAME.override(value), and a variable outside the registry with envs.override_external(name, value); the env_overrides fixture keeps either until the end of the test.
    • Name a variable that only tests read FASTVIDEO_TEST_*.
    • Do not call os.environ, os.getenv, or monkeypatch.setenv for a FastVideo variable.
    • To set a variable that another tool reads, call envs.set_external, envs.setdefault_external, or envs.unset_external.
  3. Regenerate the table in the policy doc.
    • Run python fastvideo/tests/contract/test_env_policy.py.
  4. Run the contract test.
    • Run pytest fastvideo/tests/contract/test_env_policy.py.
    • When the test reports a fixed known violation, delete or lower its entry in KNOWN_VIOLATIONS. Never add an entry to KNOWN_VIOLATIONS.
  5. When the policy itself changes, update the policy doc and the contract test in the same pull request.
    • The rules in docs/contributing/env_vars.md, the checks and allowlist in fastvideo/tests/contract/test_env_policy.py, and this skill must agree.

Read the full file on GitHub · 80 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. 29d ago Changed · +3 lines e3ceeb085cc8
  2. 1mo ago First seen · 77 lines · 64 tokens per session scan A bfbe0e1fd0b1

Subscribe to this mod's changes

env-var-conventions is a skill published in the GitHub repository hao-ai-lab/FastVideo (4,758 stars, last pushed today), licensed Apache-2.0. It adds 64 tokens to every session and 865 once invoked, about $0.0003 per session on Opus 5.5. 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 2026-09-30.

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