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, 52 insertions, 24 deletions

diff --git a/docs/typ/reference.typ b/docs/typ/reference.typ
index e79f9c4d..916f6b33 100644
--- a/docs/typ/reference.typ
+++ b/docs/typ/reference.typ
@@ -2,7 +2,7 @@
 // does, how it fails, and the limits. How pardes behaves on screen is the
 // guide's; recipes and traps are scripting's; how a mount cuts writes and
 // the listeners are building's.
-#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
 
 Every native session is a virtual filesystem, served as 9P2000 (not .u,
 not .L), in acme's manner: panes, columns, tags and the session are
@@ -16,29 +16,57 @@ it names, or else run it as a shell line. The files #file("look") and
 
 = The tree <tree>
 
-```
-/README        the one-screen summary (src/fs-help.txt)
-/index         a line per pane: serial kind dirty name column
-/status        pid, version, panes
-/look /exec    write a line: a right / middle click at the pane with the keyboard; read: the serials touched
-/pager         write a directory: its one +Pager, made or emptied; read: its serial
-/log           the event log; write `follow` to wait for more
-/screen        the rendered screen as JSON
-/listeners     dial addresses
-/focus         the serial of the pane with the keyboard; write one to move it
-/ctl           settings and session builtins
-/commands      every builtin, one a line
-/recent        files opened lately: open|closed <path>
-/layout        a line per column, then `active <serial>`
-/tag /tagexec  the workspace tag, and a word clicked in it
-/col/<n>/      tag ctl exec of column <n>; rmdir closes an empty one
-/pane/new      open it to make a pane; read answers the serial
-/pane/<n>/     name body tag ctl addr dot limit data xdata sel dirty mark scroll
-               errors event look exec tagexec, and pty/{ctl,status,data,run} on terminals;
-               rmdir closes the pane
-/os/           the host filesystem
-/src/          the editor's sources (only with -Dembed-sources=true)
-```
+#fstree(```
+README          the one-screen summary (src/fs-help.txt)                   @other-files
+index           a line per pane: serial kind dirty name column               @rules
+status          pid, version, panes                                          @other-files
+look            write a line: a right click at the pane with the keyboard; read: the serials touched  @look-and-exec
+exec            write a line: a middle click there; read: the serials touched  @look-and-exec
+pager           write a directory: its one +Pager, made or emptied; read: its serial  @pardes-stdin
+log             the event log; write follow to wait for more                 @log
+screen          the rendered screen as JSON                                  @on-screen
+listeners       dial addresses                                               @other-files
+focus           the serial of the pane with the keyboard; write one to move it  @columns-and-tags
+ctl             settings and session builtins                                @root-ctl
+commands        every builtin, one a line                                    @other-files
+recent          files opened lately: open|closed <path>                      @other-files
+layout          a line per column, then active <serial>                      @columns-and-tags
+tag             the workspace tag                                            @columns-and-tags
+tagexec         a word clicked in the workspace tag                          @columns-and-tags
+col/            the columns                                                  @columns-and-tags
+  <n>/          column <n>; rmdir closes it when empty                       @columns-and-tags
+    tag         its tag
+    ctl         its builtins (Delcol Joincol New Tty)
+    exec        a word clicked in its tag
+pane/           the panes                                                    @panes
+  new           open it to make a pane; read answers the serial              @panes
+  <n>/          pane <n>; rmdir closes it                                    @panes
+    name        the file name; write to rename                               @panes
+    body        the text; a write appends, > replaces                        @panes
+    tag         its path, then its words; a write replaces the words         @panes
+    ctl         builtins and ctl words, a line each                          @panes
+    addr        the address data and xdata work on                           @addresses
+    dot         the selection, as an address                                 @addresses
+    limit       where a forward search stops                                 @addresses
+    data        the text at addr; a write replaces it                        @addresses
+    xdata       the text in addr's range only                                @addresses
+    sel         the selected text; a write replaces it                       @panes
+    dirty       1 while the text differs from its file                       @flags
+    mark        0 or 1; a write marks an undo point                          @flags
+    scroll      0 or 1; a write scrolls the pane                             @flags
+    errors      write-only: text for the directory's +Errors                 @panes
+    event       the pane's clicks and keys, as acme's event file             @event
+    look        a right click at this pane                                   @look-and-exec
+    exec        a middle click at this pane                                  @look-and-exec
+    tagexec     a word clicked in this pane's tag                            @look-and-exec
+    pty/        terminals only                                               @pty
+      ctl       winsize, sig, exec                                           @pty
+      status    cols rows busy                                               @pty
+      data      the live stream: bytes in as typed, output out               @pty
+      run       write a command line; read: exit N, then its output          @pty
+os/             the host filesystem                                          @mounts
+src/            the editor's sources (only with -Dembed-sources=true)        @mounts
+```)
 
 Panes and columns are named by serials the editor gives: stable while they
 live, never reused (so they can have gaps). Nothing is created by a listing, stat, walk or read: