Unicode sequences, @typeface, and the font/typeface distinction

A run of Unicode code points now needs one pair of carets, not one pair
each: ^9053 53EF 9053^ renders the characters adjacently, and a single
character inside such a run stands for itself.  An invalid code point is
an error naming the position that wrote it, rather than an apology
rendered into the finished document; noncharacters are refused alongside
surrogates; and a code point that lands on a Klammertext special is safe
through the re-reads that assemble a document.  The character tables now
produce the precomposed form, so a diacritic written as ^a" and one typed
directly are the same text to a search or a copy-paste.

"kdesc -u" describes how to write a Unicode character, with tables of
glyphs beside the codes that produce them.  It is new and not yet
complete: it predates the sequence form and the typeface klammer below.

A typeface and a style are no longer both called "font".  A typeface is a
family resolved by name; a style code is the one letter naming a type
style.  So @document takes :serif_typeface and its siblings, a table takes
:style, captions take :caption_style and :caption_size, the uniform scale
is :text_scale, and the command is "kdesc --typeface".  This renames
arguments a document may already use; an old name is a located error
rather than a silent omission.

@typeface sets a passage in another typeface for the length of that
passage:

    @typeface Noto Sans Egyptian Hieroglyphs | ^132AA 133CF^ :scale 1.5 @

Writing the klammer is the whole declaration -- the document resolves the
typeface, embeds it in what it produces, and carries its license along.
Two typefaces for scripts no text font covers now ship with Klammertext:
Noto Sans Egyptian Hieroglyphs and Noto Sans Cuneiform.  Every typeface in
the distribution now carries its license file.

(from dev 61e598698891)

sks/font/font.k

@@ -2,28 +2,44 @@
 @@@state font_dirs :desc Directories containing local fonts @@@
 
 
-@@@argtype font |
-  an abbreivation for a font
+@@@argtype style_code |
+  a style code: one letter naming a type style
   :pattern r^|i^|b^|s^|t^|c
 @@@
 
-@@@argtype font_list |
-  a list of font symbols. One or more of 'r' (roman), 'i' (italic),
+@@@argtype style_code_list |
+  a list of style codes. One or more of 'r' (roman), 'i' (italic),
   'b' (bold), 's' (sans-serif), 't' (typewriter or monospace) or 'c'
-  (code) for each cell in a row. If there are fewer font symbols than
-  cells in a row, the last symbol is repeated.  Extra symbols are
+  (code) for each cell in a row. If there are fewer style codes than
+  cells in a row, the last code is repeated.  Extra codes are
   ignored.
-  :pattern ('font'^|\s)+
+  :pattern ('style_code'^|\s)+
   :python_cast (lambda s : s.split())
   :default r
 @@@
 
-@@font.k fontname : Switch to an available font for PDF output. @@
+#[
+@font was retired 2026-08-25 and replaced by @typeface.  It switched the
+main font PERMANENTLY (a bare \setmainfont, no group) for tex, and for
+html and txt its body was "*fontname*" -- so it printed the NAME of the
+font as document text instead of setting anything.  @typeface is the
+temporary, all-target replacement.
+]#
 
-@@font.html :: *fontname* @@
-@@font.tex  :: \setmainfont[Ligatures=TeX]{*fontname*} @@
-# @@font.tex : \setmainfont[Ligatures=TeX,Numbers=Lining]{*fontname*} @@
-@@font.txt :: *fontname* @@
+@@typeface.k name | text :scale.float 1.0 :
+A temporary change of typeface for *text*: the typeface *name* is
+resolved in the Klammertext font store (the directories of
+KLAMMERTEXT_FONTS, then the distribution's own), and the document
+declares and localizes it automatically -- writing this klammer is the
+only declaration needed.  *scale* multiplies the surrounding text size,
+which a script whose glyphs are drawn small usually wants.
+
+The change ends with *text*: nothing after it is affected.  Under the
+txt target a typeface cannot be expressed at all, so *text* is emitted
+unchanged.
+@@
+
+@@typeface.html,tex,txt :: @eval font.Typeface(K) @ @@
 
 @@r.k text : Use the current Roman font for *text* @@
 @@r.html :: <span class="plain">*text*</span> @@
@@ -74,10 +90,21 @@
 \setmainfont{Garamond Libre}
 @@
 
-@@cjk.k text : Switch to font that supports CJK for *text* @@
-@@cjk.html :: *cjk* @@
-@@cjk.tex  :: { #- @font Noto Sans CJK SC @ *cjk* #- } @@
-@@cjk.txt  :: *cjk* @@
+#[
+Before 2026-08-25 every one of these bodies substituted "*cjk*" while the
+declaration named the parameter "text", so @cjk raised "Variable "cjk" not
+defined" under EVERY target -- it had never worked.  Rewritten on
+@typeface, which is what it was reaching for.
+
+The typeface it names is NOT part of the distribution (a usable Noto Sans
+CJK is some 16-20 MB per weight, and Chinese line breaking needs more
+than a typeface -- xeCJK for the tex path), so this klammer errors with
+the list of available typefaces until one is installed with
+"kdesc --typeface install".  That is the honest behaviour: the klammer
+states what it needs and the store reports what it has.
+]#
+@@cjk.k text : Set *text* in a typeface that supports CJK @@
+@@cjk.html,tex,txt :: @typeface Noto Sans CJK SC | *text* @ @@
 
 @@fraktur.k s : Set text *s* in Fraktur @@
 @@fraktur.tex :: \textfrak{*s*} @@