Trace how a subsystem actually works before changing it. Use for "how does X work", a walkthrough before an edit, or placement questions ("where should this live", "which package owns this"). Fans out read-only explorers for a subsystem, one explainer for a narrow question. Use `why` for motivation, `alternatives-considered` for options.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# How
Build a working mental model of code you are about to change. The output is
the mechanism, not annotated source.
Feeds `principle-prove-it`: you cannot exercise the real artifact until you
know which artifact is real.
## Step 1. Size the question
State your reading of the scope in one line, then proceed. The user can
redirect.
- **Narrow** — one module, one function, one file. No fan-out. Read and
explain in a single pass. Go to Step 3.
- **Broad** — a subsystem across files or packages, a cross-cutting flow, an
architectural overview. Fan out first. Go to Step 2.
When it is ambiguous, take the narrow path. A second pass is cheaper than
four subagents answering a question that had one file in it.
## Step 2. Fan out (broad only)
Split the question into 2–4 angles that do not overlap. Spawn all explorers
in **one message** so they run concurrently:
- `subagent_type: Explore` (or `general-purpose` where Explore is absent)
- read-only; no edits, no worktree needed
Each explorer owns one angle and returns rows in the shape at
`corpus/skills/principle-prove-it/references/finding-shape.md`.
**Prompt hygiene:** give each explorer the question and the entry points,
…
The line at the top of this page pins the label git:20260909.2dc9a9f, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
GET https://markdownregistry.com/api/v1/artifacts/art_eztdg3ms6pdby7p2
GET https://markdownregistry.com/api/v1/resolve?ref=edbertchan/catstack/how
GET https://markdownregistry.com/api/v1/blob/e4bb0db99d42fa45040986acad1c8217be020d178321a967f80f65365b1413f0
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
edbertchan/catstack · corpus/skills/cat-mode/SKILL.md · Edbert's personal working conventions, mined from real session history across his projects. Use when Edbert asks to…
edbertchan/catstack · corpus/skills/principle-assert-invariants-not-last-bug/SKILL.md · Apply after a bug ships past review or a passing grade/check: assert the general class of failure instead of patching…
edbertchan/catstack · corpus/skills/principle-bind-to-named-inventory/SKILL.md · Apply after an audit, scoring review, or a request for a "real classifier" / "less arbitrary weights" when existing…
edbertchan/catstack · corpus/skills/principle-build-the-lever/SKILL.md · Apply to any non-trivial work, not just bulk work: edits, migrations, analyses, checks. Build the tool that does it or…
edbertchan/catstack · corpus/skills/principle-encode-lessons-in-structure/SKILL.md · Apply when you catch yourself writing the same instruction a second time, or notice a recurring correction. Encode the…
edbertchan/catstack · corpus/skills/principle-experience-first/SKILL.md · Apply when product, UX, or feature-scope tradeoffs come up. Choose user delight over implementation convenience; ship…
edbertchan/catstack · corpus/skills/principle-fix-root-causes/SKILL.md · Apply when debugging. Trace each symptom to its root cause and fix it there; reproduce first, ask why until you reach…
edbertchan/catstack · corpus/skills/principle-flag-your-own-corrections/SKILL.md · Apply whenever you are about to admit fault in any wording — a fact, number, claim, or check you already stated turns…
edbertchan/catstack · corpus/skills/principle-generalize-from-rejection/SKILL.md · Apply when a mechanical gate — a lint, validator, blocked-command guard, or CI check — rejects your output for the same…
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cursor/plugins · harness/pstack/claude-code/skills/how/SKILL.md · Use for "how does X work", code walkthroughs before changing something, and placement / ownership / layering questions…
michael-denyer/pstack-claude · plugins/pstack/skills/how/SKILL.md · Use for "how does X work", code walkthroughs before changing something, and placement / ownership / layering questions…
backnotprop/pstack · skills/how/SKILL.md · Use for "how does X work", code walkthroughs before changing something, and placement / ownership / layering questions…
bastani-inc/atomic · packages/workflows/skills/how/SKILL.md · Use for "how does X work", code walkthroughs before changing something, and placement / ownership / layering questions…
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creedants/pstack-t3 · skills/how/SKILL.md · Use for "how does X work", code walkthroughs before changing something, and placement / ownership / layering questions…
creedants/pstack-t3 · t3/overrides/how/SKILL.md · Use for "how does X work", code walkthroughs before changing something, and placement / ownership / layering questions…
