c-explain

c-explain is a skill for Claude Code, Codex from sentasity/cadence. It costs 159 tokens per session (2,075 once invoked), scanned A, original, MIT.

An interactive guide helps you understand an existing software design or implementation plan by presenting its structure and answering questions using the documents and related code.

In plain words
What is it for?
Use it for plain-language orientation and question-and-answer discussions about a complete design, plan, individual document, or selected section.
Why use it?
It removes the need to navigate a large design or plan alone. When implementation details arise, it connects explanations to both the relevant design sections and code locations.

Skill for Claude CodeCodex

Installs and runs on its own, but its text points at files inside its plugin — anything it tells you to read at a ${CLAUDE_PLUGIN_ROOT} path is only there once the plugin is installed. Installing the plugin gets both.

Part of the cadence plugin — 11 skills, 5 agents, 1 hook shipped together

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.

agentmods
npx agentmods add skills/sentasity/cadence/c-explain
Any agent
npx skills add sentasity/cadence --skill c-explain
Clone the repo
git clone --depth 1 https://github.com/sentasity/cadence

Made for: Claude Code, Codex.

Or install cadence, the plugin that ships this one along with the rest of its 11 skills, 5 agents, 1 hook.

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 c-explain

README.md
[![agentmods](https://agentmods.dev/badge/skills/sentasity/cadence/c-explain.svg)](https://agentmods.dev/skills/sentasity/cadence/c-explain)
Your own site
<a href="https://agentmods.dev/skills/sentasity/cadence/c-explain"><img src="https://agentmods.dev/badge/skills/sentasity/cadence/c-explain.svg" alt="Measured on agentmods" height="20"></a>
Per session 159 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,075 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00159 $0.02075
Opus 5 $0.00079 $0.01038
Sonnet 5 $0.00032 $0.00415
Haiku 4.5 $0.00016 $0.00208

Measured 4d ago against content hash d3a09a82ae6a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

c-explain 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 4d 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/c-explain/SKILL.md · 126 lines

How it starts

The opening of the file, as written. The whole thing — 126 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/c-explain

You run an interactive discussion of an existing design or plan. The user drives the questions; you ground answers in the doc and the code under it. You never critique (that's /c-check), never hunt defects (that's /c-find-bugs), and never write a new design or plan.

Invocation forms

  • /c-explain <design-folder-path> — whole design.
  • /c-explain <plan-folder-path> — whole plan.
  • /c-explain <single-doc-path> — one child doc in isolation.
  • /c-explain <doc-path>#<heading> — sub-section anchor (heading slug or H2/H3 title).
  • /c-explain --any <path> — bypass the Cadence-layout check for imported/external docs.

Entry contract

Refuses when: the target does not resolve to an artifact; OR the target is in a Cadence-managed location and the resolved artifact lacks the expected structure (no overview, missing frontmatter) — check existence and structure via skills/_shared/storage-resolution.md (artifact_exists) in the active backend — unless --any is set.

Phase 1 — Parallel context scan

Before the first user question, all in parallel:

  • Read the target doc(s) via skills/_shared/storage-resolution.md (read_artifact). For a folder target, read the overview + all child docs; for a section anchor, scope to that section but still load the parent doc's frontmatter for context. Do not assume a paths.designs/paths.plans file path.
  • Resolve config by running node "${CLAUDE_PLUGIN_ROOT}/scripts/resolve-config.js" and use its JSON config (paths, naming, advisor list); contract in skills/_shared/config-resolution.md; never read config files directly.
  • Extract File Map references from the doc(s) — note which code files are claimed to exist under this design's implementation.
  • git log -20 --oneline -- <slug-or-paths> to surface recent changes touching the design's area.
  • Read the repo's CLAUDE.md if any.

The scan is invisible — it sharpens the orientation, doesn't produce a report.

Phase 2 — Orientation (one screen)

Read the full file on GitHub · 126 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. 4d ago First seen · 126 lines · 0 tokens per session scan A d3a09a82ae6a

Subscribe to this mod's changes

c-explain is a skill published in the GitHub repository sentasity/cadence (1 stars, last pushed 10d ago), licensed MIT. It adds 159 tokens to every session and 2,075 once invoked, about $0.0008 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 2026-08-31.