Write Docs skill

Write Docs

A doc is a glossary: it names the moving parts, says why each exists, and carries the principles a reader can't derive by grepping. The code is the source of truth for what exists right now — the doc must never race it. Before writing any line, ask the one question that governs this skill: could the reader get this faster and more reliably by reading the code? If yes, point them at the code instead of copying it in.

Keep vs shed

Keep — a reader cannot grep their way to these:

• The WHY: why a thing exists, the principle behind a split, the taxonomy file names don't reveal.
• Non-obvious discoveries: platform quirks, "if you remove this, X breaks because Y", a contract two files silently share.
• Pointers to where things live, and what KIND of thing lives there plus the rule for what belongs.

Shed — the code or its git history already holds these, so a copy only rots:

• Exact rosters: scene names, scenario tables, helper lists, class ids, file lists, command/flag matrices.
• Narrative and changelog: "we renamed X", "the old Y was removed as a dup", what was tried and abandoned.
• Exact counts, tick values, current constants, line numbers — anything that just restates the code.

Point, don't transcribe

Where you're tempted to list specifics, name the folder or the single file that owns them and send the reader there — prefer a folder over a file, a source-of-truth registry over a transcribed copy. Describe a helper module by the kind of helper it holds and the rule for what belongs in it, not its current roster. One concrete touchstone is fine to ground a principle; a full inventory is the smell. "The matchups live in the table that defines them; the ids key off the class registry" stays true after the next edit — reproducing either does not.

One home per fact

Every fact has exactly one canonical home; every other doc links to it. Repetition across docs is a maintenance bug — copies drift and the reader can't tell which is current. A root/global doc gets a short section plus pointers to the sub-docs. When two docs explain the same thing, pick the hub and cut the other to a pointer.

Link the tree, downward

Docs form a tree reachable from one root/hub doc: the hub links to each sub-doc, and a sub-doc links on to any module-level doc beneath it. Navigation flows down — a reader starts at the root and follows links in, so the whole tree is reachable from there. A doc links back up to its parent, or across to a sibling, only to reuse a fact that already lives there — an app doc pointing at the hub's deployment section instead of restating it, a boundary doc naming the sibling it defers to. That is the one-home rule doing its job. What you do not add is a rote "part of X" back-link that carries no information: it's noise, and the tree is already navigable from the root without it.

Edit pass

When trimming an existing doc, delete on sight: enumerations of code-discoverable items, changelog and narrative, and any sentence that restates the code. Then read what survives as a stranger with no conversation history — every remaining line should be a principle, a why, or a pointer. If a line would be just as true and just as useful as a link, make it the link.