Answer principles round 1: 3 🔴, 8 🟡 (0 misread); attributes as data-*, carried content as paragraphs, links and notes, no character HTML cannot hold, mutants killed

spec/html.md

@@ -15,8 +15,8 @@ document whose `content` is an empty array is the empty string.
 | `heading`, `level` 1 to 6 | `<h1>…</h1>` to `<h6>…</h6>` |
 | `blockquote` | `<blockquote>`, a line feed, its blocks, a line feed, `</blockquote>` |
 | `bulletList` | `<ul>`, a line feed, its items a line each, a line feed, `</ul>` |
-| `orderedList` | as `bulletList` with `<ol>`; `<ol start="3">` for an `order` of 3, a safe integer; no `start` where the list holds no `order` |
-| `listItem` | `<li>…</li>`: a first paragraph holding content bare, its inline content straight after `<li>`, then each other block after a line feed and a line feed before `</li>`; with no bare paragraph, `<li>`, a line feed, its blocks, a line feed, `</li>` |
+| `orderedList` | as `bulletList` with `<ol>`; `<ol start="3">` for an `order` of 3, a safe integer other than `-0`; no `start` where the list holds no `order` |
+| `listItem` | `<li>…</li>`: a first paragraph holding content and no attribute bare, its inline content straight after `<li>`, then each other block after a line feed and a line feed before `</li>`; with no bare paragraph, `<li>`, a line feed, its blocks, a line feed, `</li>` |
 | `codeBlock` | `<pre><code class="language-js">…</code></pre>`, the language one token holding no whitespace; no `class` where it holds no `language` |
 | `rule` | `<hr>` |
 | `mediaSingle`, centered, holding one external `media` | `<p><img src="…" alt="…"></p>`, no `alt` where the media holds none; `<p><a href="…"><img …></a></p>` where a link marks it |
@@ -24,6 +24,12 @@ document whose `content` is an empty array is the empty string.
 A container holding no `content` key is its element holding nothing: `<blockquote></blockquote>`,
 `<ul></ul>`, `<li></li>`; so is a paragraph or heading, `<p></p>`.
 
+Every other attribute its type holds (`spec/flavour.md` §Block nodes) is a `data-*` attribute on the
+element, named as HTML's `dataset` names it, `localId` as `data-local-id`, after the element's own
+attributes and sorted by name. A string is its value; any other value is its JSON, compact:
+`<ol start="3" data-local-id="91177a27-b0ff">`, `<pre data-wrap="true"><code>`. A code block's
+`data-*` attributes stand on its `<pre>`.
+
 ## Inline
 
 | ADF | HTML |
@@ -39,43 +45,58 @@ marks are two `<a>` elements.
 
 ## Escaping
 
-Text and attribute values escape `&`, `<`, `>` and `"` as `&amp;`, `&lt;`, `&gt;` and `&quot;`,
-and a carriage return as `&#13;`, which an HTML parser would otherwise read as a line feed.
+Text and attribute values escape `&`, `<`, `>` and `"` as `&amp;`, `&lt;`, `&gt;` and `&quot;`.
 Attribute values are double-quoted. A link's `href` and an image's `src` are the URL as the ADF
 holds it, whatever its scheme (`docs/decisions.md` §HTML writes a URL as the ADF holds it, whatever
 its scheme).
 
+HTML text and attribute values cannot hold a carriage return, which a parser reads as a line feed,
+a control other than a tab, line feed or form feed, a noncharacter, or a lone surrogate, which
+UTF-8 cannot encode (WHATWG HTML §13.1.3). A node holding one in a value its element writes rides
+the carry.
+
 ## The carry element
 
 A node the sections above cannot write where it stands is the carry element: `<div>` in block
 position, `<span>` inline, of class `adf-carry`, holding the node's JSON in `data-adf` and showing
-the node's text. A carry element may hold a node the sections above write, as the markdown carry
-may: it reads back as the node it holds, so HTML stored while a node rode the carry reads the same
-once a later release writes it as its own element.
+its content. A carry element may hold a node the sections above write, as the markdown carry may:
+it reads back as the node it holds, so HTML stored while a node rode the carry reads the same once a
+later release writes it as its own element.
 
 ```html
-<div class="adf-carry" data-adf="{&quot;attrs&quot;:{&quot;panelType&quot;:&quot;info&quot;},…,&quot;type&quot;:&quot;panel&quot;}">Check the collation.</div>
+<div class="adf-carry" data-adf="{&quot;attrs&quot;:{&quot;panelType&quot;:&quot;info&quot;},…,&quot;type&quot;:&quot;panel&quot;}"><p>Read the <a href="https://spec.commonmark.org/">CommonMark spec</a> first.</p><p>Then import.</p></div>
 <p>Ask <span class="adf-carry" data-adf="{&quot;attrs&quot;:{&quot;id&quot;:&quot;5b10a2&quot;,&quot;text&quot;:&quot;@Mikael&quot;},&quot;type&quot;:&quot;mention&quot;}">@Mikael</span></p>
 ```
 
 - `data-adf` holds the node's JSON compact, keys sorted, as `!adf:carry` does in markdown, its type
-  included. A document holding no `content` key is the block carry of `{"type":"doc","version":1}`.
-- The text shown is every text node's text below the node, and what a node holding no text shows
+  included, each character HTML cannot hold spelled as a JSON escape, `\u0085`. A document holding
+  no `content` key is the block carry of `{"type":"doc","version":1}`.
+- The content shown is every text node's text below the node, and what a node holding no text shows
   in its place: a mention's text, else `@` and its id; an emoji's text, else its `shortName`; a
   status's text; a date as `2026-09-13` in UTC; a card's URL, else its name, else the URL its data
-  holds; media's `alt`, else an external one's URL; an extension's text; an expand's title. A line
-  feed parts two blocks and stands for a hard break. Null characters are dropped.
-- A node rides the carry where it holds an attribute, mark or key its element does not write, an
-  empty `attrs`, `content` or `marks`, or a value its element cannot hold:
-  - text holding no character, or a null character, which HTML cannot hold; text holding a mark
-    twice, or a mark with attributes besides a link's `href` and `title`;
+  holds; media's `alt`, else an external one's URL; an extension's text; an expand's title.
+  - In a `<div>`, each block's content is a `<p>`; in a `<span>`, `<br>` parts two blocks'.
+  - A hard break and a line feed in text are `<br>`.
+  - Text a link marks is `<a href="…" title="…">` around it, and a card or an external image is a
+    link to its URL.
+  - A node referencing what it cannot show is a note naming it, `<em>(image)</em>`: `image` for
+    media with no `alt` or URL, `link card` for a card with neither URL nor name, an extension's
+    key, else `extension`, for an extension with no text, and `synced block` for a `syncBlock`.
+  - Characters HTML cannot hold are dropped.
+- A node rides the carry where it holds a mark or a key its element does not write, an attribute
+  its type does not hold as that kind, an empty `attrs`, `content` or `marks`, or a value its
+  element cannot hold:
+  - text holding no character, or a character HTML cannot hold; text holding a mark twice, or a
+    mark with attributes besides a link's `href` and `title`;
   - an unmarked text node straight after another, which would read back as one;
-  - a link whose `href` or `title` holds a null character, and an image whose `url` or `alt` holds
-    one or whose link's `href` or `title` does;
-  - a code block holding more than one text node, a marked one, or a language holding whitespace
-    or a null character;
-  - a list holding a node that is no `listItem`, or an item holding attributes or marks: the whole
-    list rides the carry;
+  - a link whose `href` or `title` holds a character HTML cannot hold, and an image whose `url` or
+    `alt` holds one or whose link's `href` or `title` does;
+  - a heading whose `level` is not 1 to 6, and an ordered list whose `order` is not a safe integer
+    or is `-0`;
+  - a code block holding more than one text node, a marked one, or a language holding whitespace;
+  - a rule or hard break holding `content`;
+  - a list holding a node that is no `listItem`, or an item holding a mark, text, an empty key or
+    an attribute its type does not hold: the whole list rides the carry;
   - a `listItem` outside a list, an inline node in block position and a block node inline.
 - A block carry's JSON nests at most 500 levels less the depth it stands at, an inline carry's at
   most 500, as in markdown.