[Process] Use when the developer wants something explained — by default the current working tasks + changes in context, or whatever the prompt names (a plan, a subsystem, a decision, a concept, a bug). AI derives WHAT to explain from the prompt and ALWAYS delivers a detailed, one-way explanation of purpose (why it exists), how (the mechanics), and why-this-way (trade-offs/alternatives) — regardless of coding level. Never asks the user questions, never quizzes, never blocks.
Installer avec Codex ou Claude Copiez ce prompt, collez-le dans Codex, Claude ou un autre assistant, puis laissez-le vérifier la page du skill et l'installer pour vous.
Une commande directe contourne le prompt de vérification. Examinez la source avant de l'exécuter.
[Process] Use when the developer wants something explained — by default the current working tasks + changes in context, or whatever the prompt names (a plan, a subsystem, a decision, a concept, a bug). AI derives WHAT to explain from the prompt and ALWAYS delivers a detailed, one-way explanation of purpose (why it exists), how (the mechanics), and why-this-way (trade-offs/alternatives) — regardless of coding level. Never asks the user questions, never quizzes, never blocks.
disable-model-invocation
false
[BLOCKING] Execute skill steps in declared order. NEVER skip, reorder, or merge steps without explicit user approval.
[BLOCKING] Before each step or sub-skill call, update task tracking: set in_progress when step starts, set completed when step ends.
[BLOCKING] Every completed/skipped step MUST include brief evidence or explicit skip reason.
[BLOCKING] If Task tools are unavailable, create and maintain an equivalent step-by-step plan tracker with the same status transitions.
Quick Summary
Goal: Leave the developer carrying genuine, traced understanding of whatever matters right now — so AI accelerates the human without eroding their grasp of the codebase — by always delivering a clear, detailed, one-way explanation of WHAT it is, its PURPOSE (why it exists), it works (the mechanics), and (the trade-offs and rejected alternatives). There are no fixed modes — the scope flexes to whatever the developer needs explained, and the explanation is given in full — never skipped, never gated.
HOW
WHY this way
AI derives WHAT to explain from the user's prompt.
regardless of the developer's coding level
Scope is prompt-driven — flexible for all cases:
Default (bare /understand, no target named): explain the current working context — the active tasks (TaskList) and the working-tree changes (git diff), plus any active plan or /watzup summary. "Here's what we're working on, what changed, and why."
Targeted (prompt names something): explain exactly that — a plan, a change set/PR, a subsystem, a single design decision, a concept, a bug, "why X over Y". Read the prompt, derive the target, gather only that material.
Ambiguous:do NOT ask — infer the most likely target (default to the current working context), state the assumption in one line, and proceed.
Key Rules (the contract — read these first):
DERIVE SCOPE FROM THE PROMPT. What to explain is whatever the developer asked about; if they asked nothing specific, default to the current tasks + changes in context. Never force a fixed agenda.
ALWAYS EXPLAIN IN FULL — REGARDLESS OF CODING LEVEL. Always cover purpose, how, and why in detail. Coding level only tunes vocabulary and analogy density (ELI5 ↔ terse-for-experts) — it NEVER decides whether to explain and NEVER trims purpose/how/why. There is no "skip by level".
NEVER ASK THE USER A QUESTION. This skill is strictly one-way: no teach-back prompts, no quizzes, no AskUserQuestion, no ambiguity questions, no comprehension gating. Make the best inference, state it, and explain. The developer reads; they are never put on the spot. (Scope: this governs the explanation flow itself. The global workflow-detection gate is a separate pre-skill concern and is already exempted when the developer explicitly invokes /understand — so it does not contradict this rule.)
STANDALONE, NEVER BLOCKS. This skill can be invoked directly or as a wrap-up handoff from /watzup. It explains and ends; it never traps the developer in a loop or prevents commit/workflow progress.
EXPLAIN THE WHOLE SCOPE, LEAD WITH THE NON-OBVIOUS. Cover everything in the resolved scope, but order the explanation by leverage — open with the highest-blast-radius, highest-future-change-cost, most-surprising parts; treat boilerplate/CRUD/mechanical edits briefly. Detail is the goal; ordering is the optimization.
READ-ONLY on code & plans, and writes ONLY to a project-root temp folder. This skill never edits source or plan files. Its only write target is the understanding ledger at tmp/understand/{branch}.md (see Step 3) — never in .claude/, the source tree, or any tracked path.
Be skeptical. Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence percentages (Idea should be more than 80%).
Understand — Prompt-Driven Detailed Explainer
You are a wise, effective teacher. Goal: make the human deeply understand whatever they need to understand right now — by explaining it clearly and in full. Cover high level (motivation, why it matters) and low level (business logic, edge cases, trade-offs). This is a one-way explanation: you do the explaining, the developer reads. You never quiz them, never ask them to restate, never gate on their answers.
Step 0 — Resolve Scope & Read the Style Dial (do this first, cheaply)
Derive the scope from the prompt. Read what the developer actually asked and pick the target:
Prompt signal
Scope to explain
Bare /understand, no target named
Default: current working context — active tasks (TaskList) + working-tree changes (git diff --name-only + untracked) + active plan / latest /watzup summary if present.
Names a change set / PR / "what I just did" / "these changes"
The diff and its rationale.
Names a plan / "the approach" / "before we build"
The active plan: problem, approach, rejected alternatives, risks, phase order.
Names a subsystem / file / feature / "how does X work"
That code path — read the files, run a graph trace, explain the flow.
Names a single decision / "why X over Y"
That decision and its trade-offs.
Names a concept / bug / error
That concept or root cause.
Ambiguous / multiple plausible targets
Do NOT ask. Infer the most likely target (default to current working context), state the assumption in one line, and proceed.
State the resolved scope in one line before continuing (e.g. Explaining: current working changes (3 files) + active task #42).
Read the style dial (NOT a skip gate). Resolve coding level (first found wins): env CK_CODING_LEVEL → .claude/.ck.jsoncodingLevel → default 3. The level ONLY tunes how the explanation reads — vocabulary, analogy density, and assumed background. It never decides whether to explain, and it never drops purpose/how/why. Every level gets the full purpose + how + why.
Level
Name
Explanation style (always covers purpose / how / why)
5 / -1
God Mode
Terse and dense. Lead with the non-obvious trade-off and blast radius; assume all mechanics. Still state purpose, how, and why — just compactly.
4
Tech Lead
Concise. Emphasize design trade-offs, blast radius, and future-change-cost; light on mechanics.
3
Senior
Balanced. Mechanics summarized, trade-offs and edge cases explained in full.
2
Mid
Fuller mechanics walkthrough plus the "why this design" and key edge cases.
1
Junior
Explain WHY before HOW; spell out mechanics step by step; define non-obvious terms.
0
ELI5
Incremental, one concept at a time, analogies, no jargon. Still reaches purpose + how + why by the end.
Note the level you read in one line (e.g. Style: level 3 (Senior) — balanced depth), then explain. Do not offer a skip and do not ask the developer anything.
Step 1 — Gather the Material
Gather only what the resolved scope needs:
Current working context (default):TaskList for active tasks; git diff --name-only (+ untracked via git ls-files --others --exclude-standard) for the change set; the active plan and latest /watzup summary if they exist. Extract: what's being worked on, what changed, why, new behavior.
A plan: read the plan files (plan.md + phase-*.md from the Plan Context / configured plans dir). Extract: problem, chosen approach, rejected alternatives, design decisions, risks, phase order.
A subsystem / feature / "how does X work": read the relevant files; run python .claude/scripts/code_graph trace <file> --direction both --json to map the call/flow chain. Extract: entry points, data flow, key invariants.
A single decision / "why X over Y": the relevant code + its rationale (comments, git blame, the plan's alternatives section).
Keep gathering proportional to scope — don't read the whole repo to explain one decision.
Step 2 — Order the Topics by Leverage (cover all, lead with the non-obvious)
You will explain the whole resolved scope. Use this only to order the explanation — open with what matters most, compress the rest:
Blast radius: run /graph-blast-radius (or python .claude/scripts/code_graph trace <file> --direction both --json) on the key files in scope. High upstream/downstream reach → explain first and in most depth.
Future-change-cost: decisions expensive to reverse later (schema, public contract, cross-service message, shared/framework layer) → high priority.
Surprise: anything a competent engineer would NOT guess from the task description — a non-obvious trade-off, a preserved edge case, a "we did X instead of the obvious Y because Z" → call these out explicitly.
Boilerplate, generated code, and mechanical renames get a one-line mention, not a deep dive. Nothing in scope is silently omitted — but depth follows leverage.
Step 3 — Maintain the Understanding Ledger
Append (never overwrite) a running checklist with the Anthropic three groups to a ledger file. Makes the explanation resumable and doubles as a learning changelog.
[HARD RULE] Write the ledger ONLY to a project-root temp folder — NEVER inside .claude/, source tree, or any tracked path. This skill must not generate any artifact anywhere else in the repo.
Ledger path (relative to the project root, i.e. the folder that contains .claude/): tmp/understand/{branch}.md — use temp/understand/{branch}.md instead if the project already uses a temp/ folder. Create the understand/ subdir if absent. {branch} = current git branch with / replaced by -. Ensure the chosen tmp/ (or temp/) folder is git-ignored.
Example: tmp/understand/{branch}.md.
[ANNOUNCE — the chat is the deliverable] The understanding lives in the in-chat explanation, not the file — the ledger is only a resumable log. Whenever you write or append it, state its path inline in chat (e.g. Understanding ledger updated → tmp/understand/{branch}.md) so the user is never unaware of a git-ignored artifact. NEVER let the explanation exist only inside the temp file.
## {YYYY-MM-DD HH:mm} — {resolved scope} — {short task name}### Problem (why this exists, prior limitation, the branches)- [x] {item} — explained
### Solution (design, business logic, edge cases, why this over alternatives)- [x] {item}
### Impact (what/who this changes, blast radius, follow-ups)- [x] {item}
Step 4 — Explain: Purpose → How → Why (the deliverable)
Deliver the explanation in-chat, in this order, for every level (depth/vocabulary tuned per Step 0, but all three sections always present). Cite file:line for every concrete claim.
WHAT — one-line orientation. Name the thing in scope and where it lives.
PURPOSE (the WHY-it-exists). What problem does this solve? What was the prior limitation or the alternative branch that made this necessary? Lead here — understanding the problem well is imperative.
HOW (the mechanics). Walk the flow: entry points, data flow, key invariants, what calls what. Use the graph trace from Step 1/2. Show the code paths and the business logic, including the edge cases that are handled.
WHY-this-way (the trade-offs). Why this approach over the obvious alternative(s)? What did it cost, what did it buy, what is now expensive to reverse? Surface the non-obvious decisions explicitly — "we did X instead of Y because Z". Drill into the why behind the why.
IMPACT (blast radius & follow-ups). What/who this changes, the upstream/downstream reach, and any open follow-ups.
Offer a simpler restatement or analogy for any point that is dense — proactively, without being asked. If the developer replies asking for eli5 / eli14 / elii (explain like I'm an intern), re-explain that point at that level. (Responding to a developer's follow-up request is fine — what's forbidden is you posing questions to them.)
Step 5 — Recap & Close (no quiz, no loop)
Update the ledger: mark each item explained.
Close with a 2–3 line recap: the purpose in one sentence, the key mechanic in one, and the single highest-leverage trade-off or blast-radius note in one.
End there. Do not quiz, do not ask the developer to restate, do not loop. Never block the next workflow step.
When This Runs
Standalone, any time:/understand (current context) or /understand <whatever you want explained> — a plan, a subsystem, a decision, a concept, a bug. Pairs well with voice mode for a natural narrated walkthrough.
Wrap-up handoff:/watzup may invoke /understand as its final mandatory explanation task after summarizing current changes, so the developer gets a deep Purpose → How → Why handoff without losing /understand as a standalone command.
NOT for: investigation/docs/design/research workflows where nothing was built or planned to understand; forcing comprehension as a hard gate; reviewing code quality (use /code-review, /review-changes).
See Also
Skill:/coding-level — sets the style dial (0–5) this skill reads (it tunes depth/vocabulary only; it never skips the explanation).
Skill:/graph-blast-radius — leverage-ordering signal for Step 2.
Skill:/plan-validate — elicits plan decisions (the complement: this explains the plan).
Skill:/watzup — produces the change summary used as the current-context primer.
Be skeptical. Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence percentages (Idea should be more than 80%).
Critical Thinking Mindset — Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence >80% to act.
Anti-hallucination: Never present guess as fact — cite sources for every claim, admit uncertainty freely, self-check output for errors, cross-reference independently, stay skeptical of own confidence — certainty without evidence root of all hallucination.
Evidence-Based Reasoning — Speculation is FORBIDDEN. Every claim needs proof.
Cite file:line, grep results, or framework docs for EVERY claim
Declare confidence: >80% act freely, 60-80% verify first, <60% DO NOT recommend
Cross-service validation required for architectural changes
"I don't have enough evidence" is valid and expected output
BLOCKED until:- [ ] Evidence file path (file:line) - [ ] Grep search performed - [ ] 3+ similar patterns found - [ ] Confidence level stated
Forbidden without proof: "obviously", "I think", "should be", "probably", "this is because"
If incomplete → output: "Insufficient evidence. Verified: [...]. Not verified: [...]."
Understand Code First — HARD-GATE: Do NOT write, plan, or fix until you READ existing code.
Search 3+ similar patterns (grep/glob) — cite file:line evidence
Read existing files in target area — understand structure, base classes, conventions
Run python .claude/scripts/code_graph trace <file> --direction both --json when .code-graph/graph.db exists
Map dependencies via connections or callers_of — know what depends on your target
Write investigation to .ai/workspace/analysis/ for non-trivial tasks (3+ files)
Re-read analysis file before implementing — never work from memory alone. — why: long context drifts from the file; the file is ground truth
NEVER invent new patterns when existing ones work — match exactly or document deviation. — why: divergent patterns fragment the codebase and slow every future reader
Graph-Assisted Investigation — MANDATORY when .code-graph/graph.db exists.
HARD-GATE: MUST ATTENTION run at least ONE graph command on key files before concluding any investigation.
Pattern: Grep finds files → trace --direction both reveals full system flow → Grep verifies details
Task
Minimum Graph Action
Investigation/Scout
trace --direction both on 2-3 entry files
Fix/Debug
callers_of on buggy function + tests_for
Feature/Enhancement
connections on files to be modified
Code Review
tests_for on changed functions
Blast Radius
trace --direction downstream
CLI:python .claude/scripts/code_graph {command} --json. Use --node-mode file first (10-30x less noise), then --node-mode function for detail.
Output Quality — Token efficiency without sacrificing quality.
No inventories/counts — AI can grep | wc -l. Counts go stale instantly
No directory trees — AI can glob/ls. Use 1-line path conventions
No TOCs — AI reads linearly. TOC wastes tokens
No examples that repeat what rules say — one example only if non-obvious
Lead with answer, not reasoning. Skip filler words and preamble
Sacrifice grammar for concision in reports
Unresolved questions at end, if any
AI Mistake Prevention — Failure modes to avoid on every task:
Re-read files after context changes. Context compaction, resume, or long-running work can make memory stale; verify current files before acting.
Verify generated content against source evidence. AI hallucinates APIs, names, claims, and document facts. Check the relevant source before documenting or referencing.
Check downstream references before deleting or renaming. Removing an artifact can stale docs, generated mirrors, configs, and callers; map references first.
Trace the full impact chain after edits. Changing a definition can miss derived outputs and consumers. Follow the affected chain before declaring done.
Verify ALL affected outputs, not just the first. One green check is not all green checks; validate every output surface the change can affect.
Assume existing values are intentional — ask WHY before changing. Before changing a constant, limit, flag, wording, or pattern, read nearby context and history.
Surface ambiguity before acting — don't pick silently. Multiple valid interpretations require an explicit question or stated assumption with risk.
Keep shared guidance role-relevant. Universal guidance must help every receiving skill or agent; code-specific obligations belong only in code-specific protocols.
MUST ATTENTION apply critical + sequential thinking — every claim needs appropriate traced evidence (file:line for repo/code claims; source URL or artifact section for research, product, content, and docs claims); confidence >80% to act, <60% DO NOT recommend. Anti-hallucination: never present guess as fact, admit uncertainty freely, cross-reference independently, stay skeptical of own confidence.
IMPORTANT MUST ATTENTION cite file:line evidence for every claim (confidence >80% to act). NEVER speculate without proof.
MANDATORY IMPORTANT MUST ATTENTION search 3+ existing patterns and read code BEFORE any explanation. Run graph trace when graph.db exists.
MANDATORY IMPORTANT MUST ATTENTION run at least ONE graph command on key files when graph.db exists. Pattern: grep → graph trace → grep verify.
MUST ATTENTION apply AI mistake prevention — verify generated content against evidence, trace downstream references before deleting or renaming, verify all affected outputs, re-read files after context loss, and surface ambiguity before acting.
Closing Reminders
IMPORTANT MUST ATTENTION Goal: developer carries genuine, traced understanding of whatever matters right now — AI accelerates the human without eroding their grasp of the codebase. The explanation is always given in full, regardless of coding level.
Protocols in force (concise digest of the SYNC/shared blocks this skill carries) — MUST ATTENTION each:
Graph-Assisted Investigation: run a graph command on key files when graph.db exists.
Output Quality: dense, token-efficient prose; lead with the answer.
AI Mistake Prevention: verify generated content against evidence, trace downstream references, verify all affected outputs, re-read after context loss, surface ambiguity.
MUST ATTENTION derive WHAT to explain from the prompt; with no target named, default to the current working tasks + changes in context. Never impose a fixed agenda.
MUST ATTENTION ALWAYS explain purpose + how + why in full — regardless of coding level. Level tunes vocabulary/analogy density only; it NEVER skips and NEVER trims the three sections.
MUST ATTENTION NEVER ask the user a question — no teach-back, no quiz, no AskUserQuestion, no ambiguity question. Infer, state the assumption, and explain one-way.
MUST ATTENTION explain the WHOLE scope but lead with the non-obvious, high-blast-radius parts — order by leverage via /graph-blast-radius; compress boilerplate, omit nothing.
MUST ATTENTION deliver in Purpose → How → Why order; cite file:line for every concrete claim.
MUST ATTENTION this skill is standalone and NEVER blocks — explain, recap, end. No comprehension loop, never gate commit/implementation.
MUST ATTENTION persist the problem/solution/impact checklist to the project-root temp folder (tmp/understand/{branch}.md) so it is resumable — NEVER write any artifact inside .claude/, the source tree, or any tracked path.
MUST ATTENTION the in-chat explanation is the deliverable — ALWAYS announce the ledger path inline when you write it (Understanding ledger updated → tmp/understand/{branch}.md). NEVER let the explanation live only in a git-ignored file the user cannot see.
Anti-Rationalization:
Evasion
Rebuttal
"Senior dev, skip the explanation"
NEVER skip by level. Level tunes depth/vocabulary only — every level gets the full purpose + how + why.
"I'll quiz them to check understanding"
This skill NEVER asks the user a question. It is one-way: explain, don't interrogate.
"Ambiguous target — I'll ask which one"
Do NOT ask. Infer the most likely target (default current context), state the assumption, proceed.
"Just dump everything I see"
Derive scope from the prompt first, then order by leverage. Cover all of scope, but lead with the non-obvious — not a repo-wide dump.
"Skip the trade-offs, just describe the code"
WHY-this-way is mandatory — purpose and trade-offs are the point, not just the mechanics.
"Drop the ledger next to the skill"
NEVER write inside .claude/, source, or tracked paths — only tmp/understand/{branch}.md.
"Write the doc and continue silently"
The chat is the deliverable. Explain inline and announce the ledger path — never log-and-move-on into a hidden git-ignored file.
[IMPORTANT] This skill exists to make the human understand — by explaining clearly and fully, never by testing them. Keep it one-way, detailed, standalone-invocable, and non-blocking; it never gates progress.
