Width and height argtypes, kdesc --argtypes from ref/, txt @define/@left_right/@columns, kdiag --check value validation (from dev d6993110e9b3)

Also: the klammertext argtype (descriptions kept as source), txt table
wrapping and :hpos/:offset, @c between ‹ ›, txt section headings, the
ktext newline-only trim, capitalize(), and the argtype test suite.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

doc/klammertext_for_llm.md

@@ -51,10 +51,12 @@ shows as `name.type default`, an option as `:name.type default`.
 kdiag --process --check doc.kt
 ```
 
-reports every klammer application whose name, argument count, option names, or
-target coverage is wrong — including inside `@cond` branches this render will
-not take and inside klammer bodies never applied. It applies nothing. Use it
-before claiming a document is correct.
+reports every klammer application whose name, argument count, option names,
+target coverage, or **literal argument value** is wrong (a value that fails
+its argument type, such as `:width .5h`) — including inside `@cond` branches
+this render will not take and inside klammer bodies never applied. A value
+holding a nested klammer or a `*variable*` is computed at run time and is not
+judged. It applies nothing. Use it before claiming a document is correct.
 
 **Inspect how text is parsed:** `kdiag --type '<text>'` shows the katoms and
 their types; `kdiag --args '<text>'` shows how text splits into arguments;
@@ -227,8 +229,8 @@ which reads `kt/preface.kt`, `kt/one.kt`, `kt/two.kt` beside the root file.
 ktext doc.kt -t pdf          # also: -t html, -t tex
 ktext doc.kt -t html         # writes a DIRECTORY doc/ containing index.html (+css, fonts, js)
 ktext doc.kt -t txt -d       # -d displays on stdout instead of writing -- but this
-                             #   example errors under txt/ansi: @c and @image have no
-                             #   txt definition (§5), and coverage is never silently degraded
+                             #   example errors under txt/ansi: @image has no txt
+                             #   definition (§5), and coverage is never silently degraded
 ktext -s '@i-x' -t html -d   # -s takes a string; no file needed
 ktext doc.kt -s '@@version : 3.2.1 @@' -t pdf   # -s is processed BEFORE the files:
                                                 #   define a klammer the document uses
@@ -274,11 +276,12 @@ Bar depth is the dimension: one `|` separates items, two `||` separates rows.
 Argument order is free for options, fixed for positionals.
 
 **Coverage today** (`kdesc --coverage`; 89 klammers): html, tex and pdf cover
-nearly all. **txt and ansi cover 37**, among them `@b @i @t @u @s @r @ri @ts
+nearly all. **txt and ansi cover 40**, among them `@b @i @t @u @s @r @ri @ts
 @typeface`, `@s1`–`@s7`, `@par @newpage @vspace @vfill @nl`, `@indent @right
-@lines @qa`, `@ul @ol`, `@table @tbl @reference`, `@footnote @link`, `@date
-@datetime`. Not for txt: `@c @code @source_listing @image @image_grid @quote
-@note @center @block @columns @multicolumn @define @sup @sub @color @h1`–`@h7`.
+@lines @qa`, `@ul @ol`, `@table @tbl @reference @define @left_right`,
+`@footnote @link`, `@date @datetime`, `@c`. Not for txt: `@code
+@source_listing @image @image_grid @quote @note @center @block @columns
+@multicolumn @sup @sub @color @h1`–`@h7`.
 `@u` has no html definition. A klammer applied under a target that lacks it is
 an **error**, never silently dropped.
 
@@ -328,7 +331,7 @@ the range (here: one sum per column).
 | `html` | a directory `<name>/` with `index.html`, `css/`, `fonts/`, `js/` | self-contained, fonts localized; `book` structure adds navigation, search |
 | `tex` | `<name>.tex` | XeLaTeX source; fonts via fontspec from the font store |
 | `pdf` | `<name>.pdf` | `tex` plus a xelatex run (TeX Live required) |
-| `txt` | `<name>.txt` | plain text filled to `Target_txt_width` (72), blocks indented by `Target_txt_indent` (3); tables ruled and padded; captions numbered; **37 of 89 klammers** (§5) |
+| `txt` | `<name>.txt` | plain text filled to `Target_txt_width` (72), blocks indented by `Target_txt_indent` (3); tables ruled and padded; captions numbered; **40 of 89 klammers** (§5) |
 | `ansi` | txt + SGR escape sequences | `@b`/`@i`/`@u` and table header styles shown by a terminal; **identical to txt once the escape sequences are stripped**; pick it with `-t ansi -d`; a terminal needs a font with an italic face (macOS Terminal: Menlo, not Monaco) |
 
 `k`, `o`, `*` also appear in `kdesc -t`: they are declaration pseudo-targets
@@ -368,7 +371,9 @@ ones. CJK is deliberately not shipped.
 - Separators: `:` create, `::` create inheriting parameters, `:::` override an
   existing definition, `::::` define a default a later `:` may replace.
 - Argument types: `name.type` — `string` (default), `int`, `float`, `bool`,
-  `list`, `length`, `literal` (raw content, named close required), `rest`
+  `list`, `width`/`height` (a bare number = characters / lines in every
+  target; units `em pt px`, `w pw` for widths, `h ph` for heights; the axes
+  are checked), `literal` (raw content, named close required), `rest`
   (everything left, bars included; `rest(2)` = list of lists), and any
   `@@@argtype` the klammerset declares (`kdesc --argtypes`). An argtype may
   carry `:default` and `:alone`; a klammer may override the default, never the
@@ -451,7 +456,7 @@ ones. CJK is deliberately not shipped.
   `-c`/`-u` render through `ansi` on a terminal and `txt` in a pipe.
 
 **When something is wrong:** `kdiag --process --check doc.kt` first (name,
-arity, option and coverage faults without rendering); then `kdesc -k <klammer>`
+arity, option, literal-value and coverage faults without rendering); then `kdesc -k <klammer>`
 against what was written; then `kdiag --type '<fragment>'` if the question is
 how something is parsed; then `ktext … -v 1` if the question is which file or
 klammerset was used.