Builtins are chips that link to a glossary generated from the registry, and the virtual filesystem is drawn as a tree

#word draws a builtin as a chip on the tag's ground over a rule (Look and
Exec in acme's look green and exec red), a <code class="word"> in HTML,
and links it to its entry in a new Builtins chapter wherever that
chapter is in the same output (the book, the site). The chapter is
drawn from docs/typ/builtins-tty.json and builtins-gui.json, which
`zig build builtins-json -Dplatform=tty|gui` writes from the registry
and the Help rows (src/builtins_json.zig, tools/gen_builtins_json.zig;
summaryOf in ninep/ctl.zig is now pub); style.typ merges them, marking
the window-only words. The doc steps refresh their build's file first,
and each build's unit-test fails when its file is stale. Everyday words
first (`everyday` in style.typ), then groups by leader prefix as Help
has them, then settings, the words with no path, debugging and
internals, and last an A-Z index of every word. `zig build book` joins
the doc steps.

#fstree draws a directory tree with its connectors, a description
column and links to the sections that document each file; reference.typ
draws the served tree with it, each pane, pty and column file on its
own line, and a test in config.zig checks it against ninep/tree.zig's
files both ways. The cheatsheet has a two-level version. On the site
the tree reads as `tree` text in w3m and wraps descriptions under the
names on a phone.

The site's tutor draws its B1, B2, B3 and 1-2 chords as mouse glyphs;
the landing credits Plan 9 and acme, as does the book's title page;
install.typ no longer lists the mirrors (the footer does).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 31 insertions, 2 deletions

diff --git a/docs/typ/README b/docs/typ/README
index 522d99ff..5db2cf76 100644
--- a/docs/typ/README
+++ b/docs/typ/README
@@ -35,14 +35,16 @@ Build (from the repo root):
 The contract for content files
 ------------------------------
 Start a content file with
-  #import "style.typ": key, keys, btn, chord, word, tag, addr, file, cmd, doc, pairs
+  #import "style.typ": key, keys, btn, chord, word, tag, addr, file, cmd, doc, pairs, fstree
 (a content file does not import page setup; the same file goes into the
 book, the HTML and, for the cheatsheet, the A4 page)
 and use plain markup (= headings, - lists, `raw`, *strong*) plus these.
 Never set page, fonts, colours or spacing in a content file; ask for a
 new function instead.
 
-  word(w)          a builtin or tag word, drawn as it sits in a tag.
+  word(w)          a builtin or tag word, drawn as a chip on the tag's
+                   ground; a builtin links to its entry in the Builtins
+                   chapter wherever that chapter is in the same output.
                    #word("Save")   #word("Tty+bash")
   key(k)           one press, or a sequence of presses separated by
                    spaces, drawn as one pill (Ctrl + w, g › g).
@@ -68,12 +70,39 @@ new function instead.
                    config keys detached, mapped in `topics`). A link in
                    the book and the HTML; on the A4 sheet, its name.
                    #doc("building", section: "listeners")
+  fstree(spec)     a directory tree drawn as `tree` draws one, from a raw
+                   block: two spaces of indent per level, the name (a
+                   directory ends in /), two or more spaces, a one-line
+                   description, an optional @label of the section that
+                   documents it (a link where that section is in the
+                   same output). reference.typ's tree is checked against
+                   the files the session serves.
+                   #fstree(```
+                   index     a line per pane     @rules
+                   pane/
+                     new     open: a new pane    @panes
+                   ```)
+  theme-gallery()  every theme as a picture, on the site's Themes page;
+                   nothing on paper.
   pairs(split:, ..cells)
                    a two-column table, a thing and its meaning, rows on
                    alternating tints; split: 2 sets it as two tables side
                    by side on paper. Cells alternate left, right.
                    #pairs(key("u"), [undo], keys("i", "a"), [insert])
 
+Builtins
+--------
+builtins-tty.json and builtins-gui.json are every builtin of the terminal
+and the window build (name, leader, Help's other shortcuts, arg, scope,
+setting, choices, doc), written by `zig build builtins-json -Dplatform=tty`
+and `-Dplatform=gui` from the registry and the Help rows
+(src/builtins_json.zig). style.typ merges them, marking each word "both",
+"tty" or "gui". The doc steps refresh their build's file first, and each
+build's unit-test fails when its file is stale. #word takes a name from
+either file. builtins.typ draws it as the
+glossary; `everyday`, `internals` and `builtin-groups` in style.typ say
+in what order.
+
 The drift test
 --------------
 The unit test "docs/typ names only words, keys and default tags that