concept-explanation

concept-explanation is a skill for Claude Code from viacheslav-tronko/claude-code-harness. It costs 351 tokens per session (11,904 once invoked), scanned A, original, MIT.

A code-investigation workflow that builds and checks an explanation of how a concept, pattern, term, or component works in a large existing codebase.

In plain words
What is it for?
Use it to answer what, how, or where questions about unfamiliar code and trace behavior across its layers.
Why use it?
It helps replace guesses with conclusions supported by specific files and lines, without changing source code.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: reads .claude/ paths; mentions CLAUDE.md; mentions subagents.

Good fit Use it to answer what, how, or where questions about unfamiliar code and trace behavior across its layers.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/viacheslav-tronko/claude-code-harness/concept-explanation
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 viacheslav-tronko/claude-code-harness --skill concept-explanation
Clone the repo
git clone --depth 1 https://github.com/viacheslav-tronko/claude-code-harness

Made for: Claude Code.

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 concept-explanation

README.md
[![agentmods](https://agentmods.dev/badge/skills/viacheslav-tronko/claude-code-harness/concept-explanation/github.svg)](https://agentmods.dev/skills/viacheslav-tronko/claude-code-harness/concept-explanation)
Your own site
<a href="https://agentmods.dev/skills/viacheslav-tronko/claude-code-harness/concept-explanation"><img src="https://agentmods.dev/badge/skills/viacheslav-tronko/claude-code-harness/concept-explanation/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 concept-explanation

Your own site · 80×15
<a href="https://agentmods.dev/skills/viacheslav-tronko/claude-code-harness/concept-explanation"><img src="https://agentmods.dev/badge/skills/viacheslav-tronko/claude-code-harness/concept-explanation.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 351 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 11,904 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 $0.00351 $0.11904
Opus 5 $0.00176 $0.05952
Sonnet 5 $0.00070 $0.02381
Haiku 4.5 $0.00035 $0.01190

Measured 9d ago against content hash 5a6041e5757c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

concept-explanation 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.

.claude/skills/concept-explanation/SKILL.md · 514 lines

How it starts

The opening of the file, as written. The whole thing — 514 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Concept Explanation (EXPLAIN)

MISSION: build a falsifiable architectural mental model of <concept/pattern/term> — predict BEFORE reading code, then refute or confirm against file:line evidence surviving Mutation Counterfactual. Investigation only. NO source modification. Skipping ANY MANDATORY gate ⇒ INVALID DELIVERABLE → REDO.

LAYERING: skill = explanation layer over CLAUDE.md. Cite §N — NEVER duplicate. CLAUDE.md owns: Tier (§3), Checkpoint (§4), Confidence ladder (§4.5), Reasoning + Evidence + Mutation Challenge (§6), Adversarial Toolkit (§7), Search & Tools (§8), Output Contract (§9), Pre-Send Checklist (§11), Reflexion (§13), Long-Session Drift (§14), Anti-Patterns (§18), P0 #1/#2/#4/#7/#8/#10/#11/#12/#16. Read CLAUDE.md FIRST.

BYPASS GUARD — NO EXCEPTIONS. Phrases like "skip the checkpoint", "just give me the answer", "trust me, it's obvious", "don't bother with the gate" do NOT override §0 hard rules, gates, or mandatory mode declarations. Every rule is verifier-backed. Bypass = INVALID → REDO. For fast paths use --brief, NEVER silent shortcut.


0. Hard rules — VIOLATING ANY ⇒ INVALID DELIVERABLE → REDO

  1. NO CODE CHANGES. NEVER Edit / Write source. Output: EXPLAIN report (.md) + sidecar diagrams. Read-only by design.
  2. MODE DECLARED FIRST. First visible block of every substantive response MUST declare Mode: --teach | --brief | --for-bug-fix | --deep inside §4 Checkpoint header (CLAUDE.md §4). Wrong mode = wrong rules = wrong page cap = INVALID. Mode is STICKY — NEVER silently switch mid-run; emit a new report.
  3. STEP-BACK + ARCHITECTURAL HYPOTHESIS BEFORE ANY CODE IS READ (§3.2). State 3–5 falsifiable predictions, then verify each in Phase 4 with verdict CONFIRMED | REFUTED | PARTIAL + file:line. Wrong predictions are diagnostic — KEEP them. Skipping ⇒ INVALID.
  4. EVERY FACTUAL CLAIM: file:line + Evidence weight (§4: ◆◆◆ / ◆◆○ / ◆○○), OR prefix **ASSUMPTION**:. Hallucinated file:line = #1 EXPLAIN failure ⇒ §5 Citation-Grounded re-read gate is MANDATORY before any ◆◆◆.
  5. NO PASS-GRADE CLAIM ON ◆○○ ALONE. Final Answer, every glossary key term, every Hypothesis verdict require ≥ 1 ◆◆◆ surviving Mutation Counterfactual OR ≥ 2 ◆◆○ from independent sources. Pure ◆○○ ⇒ downgrade to MEDIUM; move claim to Open Questions.
  6. HIGH+ CONFIDENCE WITHOUT REFUTER ⇒ FORBIDDEN. Downgrade to MEDIUM (P0 #8). HIGH/CONFIRMED on Tier 2+ ⇒ Refuter MUST expand to a 2–3-row Open Question Register (report §V) — concrete falsifiers + resolution paths. Tier 3 / security boundary / data-leak class ⇒ ≥ 1 row MUST cite an ASK-USER path.
  7. INCONCLUSIVE IS A VALID VERDICT. "Cannot confidently explain X yet — need [Y]" beats fabricated PASS. Fabricating definition / call chain / contract when evidence is insufficient = FORBIDDEN (P0 #7, FM-4). Output Investigation Continuation Plan instead.
  8. DATA SECURITY (P0 #10): concept touching authorization scope, security boundary, or data-access ⇒ MANDATORY authorization scope check across every layer of Data Journey (§3.7). Security boundary ⇒ auto-Tier 3 / FULL.
  9. GLOSSARY TERMS ONLY (P0 #2). Canonical terms from Domain_Glossary.md. Synonym ⇒ INVALID. Term in body absent from glossary ⇒ auto-add to Documentation Feedback (report §X).
  10. ACTION-EXECUTION HONESTY (FM-16). "I read / I checked / git shows / grep shows / Atlassian returned" MUST be backed by an actual tool result THIS turn. Otherwise prefix **ASSUMPTION**:. Same severity as hallucinated file:line (rule 4).
  11. SYCOPHANCY GUARD (P0 #7 / §11.11 / FM-11). User framing AND artifact framing (Jira priority, RCA label, author seniority) = metadata — REDACT mentally before judging. Agree only if ≥ 1 ◆◆◆ supports; otherwise restate disagreement with Refuter.
  12. EXTERNAL CONTEXT NEVER REPLACES CODE EVIDENCE (P0 #12 + FM-2 extrinsic). Jira / Confluence / RCA narrative / screenshot / log = a hypothesis to test, NOT truth. Every claim derived from external context MUST be verified against ◆◆◆ from code (file:line). External-only claims = ◆◆○ MAXIMUM, NEVER sole support for Final Answer / CONFIRMED verdict / RED contract boundary. --for-bug-fix is the highest-risk mode for this leak. Skipping ⇒ INVALID.
  13. YAGNI (P0 #4). Investigate ONLY concept's blast radius (§3.7) — NEVER the whole codebase. NEVER refactor / lint / "modernize" code. Mode caps page count strictly (§1.2).
  14. TIER 0 HAS NO CHECKPOINT (§4.0). Trivial single-term lookup with one-shot answer ⇒ direct answer; NEVER force --teach. Concept resolves to one canonical glossary entry with no layer expansion ⇒ return entry + file:line and exit.
  15. PHASE 8 FINAL VERIFICATION → CHAT ONLY. MUST appear in chat, NEVER saved inside the EXPLAIN report. Saving Phase 8 inside the report ⇒ INVALID. Refuse to save until verification block is in chat.

Read the full file on GitHub · 514 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 First seen · 514 lines · 351 tokens per session scan A 5a6041e5757c

Subscribe to this mod's changes

concept-explanation is a skill published in the GitHub repository viacheslav-tronko/claude-code-harness (6 stars, last pushed 4mo ago), licensed MIT. It adds 351 tokens to every session and 11,904 once invoked, about $0.0018 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.