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, 70 insertions, 1 deletions

diff --git a/src/config.zig b/src/config.zig
index e9595a2a..f83e7945 100644
--- a/src/config.zig
+++ b/src/config.zig
@@ -2101,9 +2101,16 @@ const doc_typ = struct {
         }
     }
 
+    /// The other build's builtins (docs/typ/builtins-*.json), so the docs
+    /// may name a window-only word in a terminal build's test, and back.
+    var other_build: []const u8 = "";
+
     fn word(w: []const u8) bool {
         const name = w[0 .. std.mem.indexOfScalar(u8, w, '+') orelse w.len];
-        return std.meta.stringToEnum(Builtin, name) != null;
+        if (std.meta.stringToEnum(Builtin, name) != null) return true;
+        var buf: [96]u8 = undefined;
+        const needle = std.fmt.bufPrint(&buf, "{{\"name\": \"{s}\",", .{name}) catch return false;
+        return std.mem.indexOf(u8, other_build, needle) != null;
     }
 
     fn chord(tok: []const u8) ?Chord {
@@ -2195,6 +2202,10 @@ test "docs/typ names only words, keys and default tags that exist" {
     var dir = try std.Io.Dir.cwd().openDir(io, @import("doc_typ").dir, .{ .iterate = true });
     defer dir.close(io);
     var found: [3]std.ArrayList([]const u8) = @splat(.empty);
+    for ([_][]const u8{ "builtins-tty.json", "builtins-gui.json" }) |f| {
+        const text = dir.readFileAlloc(io, f, gpa, .limited(1 << 20)) catch continue;
+        doc_typ.other_build = try std.mem.concat(gpa, u8, &.{ doc_typ.other_build, text });
+    }
     var it = dir.iterate();
     while (try it.next(io)) |entry| if (entry.kind == .file and std.mem.endsWith(u8, entry.name, ".typ")) {
         const source = try dir.readFileAlloc(io, entry.name, gpa, .limited(1 << 20));
@@ -2331,3 +2342,61 @@ test "the tutor names only words, keys, paths and default tags that exist" {
         }
     }
 }
+
+test "reference.typ's #fstree is the tree the session serves, file for file" {
+    const tree = @import("ninep/tree.zig");
+    var arena: std.heap.ArenaAllocator = .init(std.testing.allocator);
+    defer arena.deinit();
+    const gpa = arena.allocator();
+    const io = std.testing.io;
+    var dir = try std.Io.Dir.cwd().openDir(io, @import("doc_typ").dir, .{});
+    defer dir.close(io);
+    const source = try dir.readFileAlloc(io, "reference.typ", gpa, .limited(1 << 20));
+    const open = "#fstree(```";
+    const start = (std.mem.indexOf(u8, source, open) orelse return error.NoFsTree) + open.len;
+    const end = std.mem.indexOfPos(u8, source, start, "```)") orelse return error.NoFsTree;
+
+    // what the reference draws: a path per line, from its indent
+    var drawn: std.StringArrayHashMapUnmanaged(void) = .empty;
+    var stack: [8][]const u8 = undefined;
+    var lines = std.mem.tokenizeScalar(u8, source[start..end], '\n');
+    while (lines.next()) |line| {
+        const body = std.mem.trimStart(u8, line, " ");
+        if (body.len == 0) continue;
+        const depth = (line.len - body.len) / 2;
+        const name = body[0 .. std.mem.indexOfScalar(u8, body, ' ') orelse body.len];
+        stack[depth] = name;
+        var path: std.ArrayList(u8) = .empty;
+        for (stack[0 .. depth + 1]) |part| try path.appendSlice(gpa, part);
+        try drawn.put(gpa, path.items, {});
+    }
+
+    // what the session serves: tree.zig's files, and fs.zig's os/ and src/
+    var served: std.StringArrayHashMapUnmanaged(void) = .empty;
+    for (std.enums.values(tree.TopFile)) |f| switch (f) {
+        .root => {},
+        .new => try served.put(gpa, "pane/new", {}),
+        else => try served.put(gpa, if (f.dir()) try std.fmt.allocPrint(gpa, "{s}/", .{f.fileName()}) else f.fileName(), {}),
+    };
+    try served.put(gpa, "os/", {});
+    try served.put(gpa, "src/", {});
+    try served.put(gpa, "pane/<n>/", {});
+    for (std.enums.values(tree.PaneFile)) |f| if (f != .dir) {
+        const under = if (f.inPty() and f != .pty) "pane/<n>/pty/" else "pane/<n>/";
+        try served.put(gpa, try std.fmt.allocPrint(gpa, "{s}{s}{s}", .{ under, f.fileName(), if (f.isDir()) "/" else "" }), {});
+    };
+    try served.put(gpa, "col/<n>/", {});
+    for (std.enums.values(tree.ColFile)) |f| if (f != .dir)
+        try served.put(gpa, try std.fmt.allocPrint(gpa, "col/<n>/{s}", .{f.fileName()}), {});
+
+    var drift = false;
+    for (served.keys()) |k| if (!drawn.contains(k)) {
+        std.debug.print("reference.typ's tree lacks {s}\n", .{k});
+        drift = true;
+    };
+    for (drawn.keys()) |k| if (!served.contains(k)) {
+        std.debug.print("reference.typ's tree has {s}, which the session does not serve\n", .{k});
+        drift = true;
+    };
+    if (drift) return error.FsTreeDrift;
+}