cerul

cerul is a skill for Claude Code, Codex from cerul-ai/cerul. It costs 33 tokens per session (4,055 once invoked), scanned A, original, Apache-2.0.

Instructions for using Cerul, a command-line tool that finds evidence in videos and other long-form media. It supports searching an authorized library and answering questions with timestamps and artifact links.

In plain words
What is it for?
Use it to search approved media libraries, answer questions about their contents, and present supporting timestamps and links.
Why use it?
It avoids guessing what was said or shown in media and keeps answers tied to retrieved evidence.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Codex.

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is cerul --json --dry-run analyze ./videos/.

Good fit Use it to search approved media libraries, answer questions about their contents, and present supporting timestamps and links.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/cerul-ai/cerul
agentmods
npx agentmods add skills/cerul-ai/cerul/cerul

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.

agentmods badge for cerul

README.md
[![agentmods](https://agentmods.dev/badge/skills/cerul-ai/cerul/cerul/github.svg)](https://agentmods.dev/skills/cerul-ai/cerul/cerul)
Your own site
<a href="https://agentmods.dev/skills/cerul-ai/cerul/cerul"><img src="https://agentmods.dev/badge/skills/cerul-ai/cerul/cerul/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for cerul

Your own site · 80×15
<a href="https://agentmods.dev/skills/cerul-ai/cerul/cerul"><img src="https://agentmods.dev/badge/skills/cerul-ai/cerul/cerul.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,055 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 $0.00033 $0.04055
Opus 5.5 $0.00013 $0.01622
Sonnet 5.5 $0.00007 $0.00811
Haiku 4.5 $0.00003 $0.00405

Measured 9d ago against content hash 28592f43de97, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

cerul 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 9d 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/cerul/SKILL.md · 339 lines

How it starts

The opening of the file, as written. The whole thing — 339 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Cerul

Cerul turns local video into searchable, annotated data using the user's own model endpoints. There is no account and no server to start: run the binary and read its output. Sidecar files beside each video are authoritative; search indexes are caches that rebuild from them without model calls.

Before anything else

Run cerul --version. If it is missing, follow the installation runbook at https://github.com/cerul-ai/cerul/blob/main/docs/agent-setup.md. Do not install Rust, Python, Ollama, or system FFmpeg for this workflow, and do not switch to a source build when a download fails; report the error instead.

cerul --json upgrade reports the newest published release and installs nothing. It replaces the program only with --yes, so ask the user before running cerul upgrade --yes: it changes which build answers every later command. A build too old for a flag you need is a reason to offer the upgrade, not to work around it.

Run cerul --json auth to see whether a key is available. It reports whether a key is saved or exported, never the value. Never echo a key, print part of it, write it to a log or a commit, or read an unrelated project's .env. When no key is available, ask the user to run cerul auth set in their own terminal, or to export the key themselves.

Always pass --json

--json is the machine contract, and it is the only mode to use:

  • stdout carries exactly one JSON object, printed when the command finishes.
  • stderr carries one JSON event per line while the command runs.
  • Nothing ever prompts. A missing argument returns invalid_arguments, not a question.

Exit codes: 0 success, 2 arguments or configuration, 3 unavailable dependency or capability, 4 execution failure, 5 cancelled, 6 partial success. Read the code as well as the output. Exit 6 is not success: part of the work finished and the rest did not.

Events on stderr:

  • progress counts units of work for one station.
  • annotation_progress reports annotation work units, cached units and phase; percentage is completed planned work, not model-internal progress.
  • checkpoint marks a window that is saved and will be reused after an interruption, so a rerun resumes rather than repeating it.
  • published marks a validated annotation file that now exists, with its record count and path. Only a published file is safe to read or train on.
  • log carries human-readable notices.

Read the full file on GitHub · 339 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. 9d ago Changed 28592f43de97
  2. 13d ago Changed · +53 lines · +6 tokens per session e0f4b1648777
  3. 23d ago Changed a6cbc96bd223
  4. 24d ago Changed · -62 lines · -48 tokens per session 36e0e04b69a3
  5. 1mo ago Changed a630bb1dfe5d
  6. 1mo ago Changed · +1 lines 22d8026cdbe9
  7. 1mo ago Changed 2d22daf82573
  8. 1mo ago Changed · +86 lines a60cd015daf7
  9. 1mo ago Changed · +20 lines 4865c19bd116
  10. 1mo ago First seen · 241 lines · 75 tokens per session scan A 5993f6eedc6c

Subscribe to this mod's changes

cerul is a skill published in the GitHub repository cerul-ai/cerul (166 stars, last pushed 10d ago), licensed Apache-2.0. It adds 33 tokens to every session and 4,055 once invoked, about $0.0001 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 2026-08-30.

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