chore: release v0.4.0

[github-actions]

🤖 New release

• markdown-syntax: 0.3.0 -> 0.4.0 (⚠ API breaking changes)

⚠ markdown-syntax breaking changes

--- failure constructible_struct_adds_field: struct exhaustively constructible through public API adds field ---

Description:
A pub struct that could be exhaustively constructed with a literal using only public API has a new pub field, breaking existing exhaustive literals.
        ref: https://doc.rust-lang.org/reference/expressions/struct-expr.html
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.50.0/src/lints/constructible_struct_adds_field.ron

Failed in:
  field WikiLink.embed in /tmp/.tmpfYoVLv/markdown-syntax/src/ast.rs:876
  field WikiLink.embed in /tmp/.tmpfYoVLv/markdown-syntax/src/ast.rs:876
  field WikiLink.embed in /tmp/.tmpfYoVLv/markdown-syntax/src/ast.rs:876

--- failure enum_missing: pub enum removed or renamed ---

Description:
A publicly-visible enum cannot be imported by its prior path. A `pub use` may have been removed, or the enum itself may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.50.0/src/lints/enum_missing.ron

Failed in:
  enum markdown_syntax::ast::AutolinkKind, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/ast.rs:798
  enum markdown_syntax::prelude::AutolinkKind, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/ast.rs:798
  enum markdown_syntax::AutolinkKind, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/ast.rs:798

--- failure enum_no_repr_variant_discriminant_changed: enum variant had its discriminant change value ---

Description:
The enum's variant had its discriminant value change. This breaks downstream code that used its value via a numeric cast like `as isize`.
        ref: https://doc.rust-lang.org/reference/items/enumerations.html#assigning-discriminant-values
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.50.0/src/lints/enum_no_repr_variant_discriminant_changed.ron

Failed in:
  variant DiagnosticCode::InvalidMdx 2 -> 3 in /tmp/.tmpfYoVLv/markdown-syntax/src/diagnostic.rs:29
  variant DiagnosticCode::StrictParse 3 -> 4 in /tmp/.tmpfYoVLv/markdown-syntax/src/diagnostic.rs:31
  variant DiagnosticCode::InvalidDocument 4 -> 5 in /tmp/.tmpfYoVLv/markdown-syntax/src/diagnostic.rs:34
  variant DiagnosticCode::InvalidMdx 2 -> 3 in /tmp/.tmpfYoVLv/markdown-syntax/src/diagnostic.rs:29
  variant DiagnosticCode::StrictParse 3 -> 4 in /tmp/.tmpfYoVLv/markdown-syntax/src/diagnostic.rs:31
  variant DiagnosticCode::InvalidDocument 4 -> 5 in /tmp/.tmpfYoVLv/markdown-syntax/src/diagnostic.rs:34
  variant DiagnosticCode::InvalidMdx 2 -> 3 in /tmp/.tmpfYoVLv/markdown-syntax/src/diagnostic.rs:29
  variant DiagnosticCode::StrictParse 3 -> 4 in /tmp/.tmpfYoVLv/markdown-syntax/src/diagnostic.rs:31
  variant DiagnosticCode::InvalidDocument 4 -> 5 in /tmp/.tmpfYoVLv/markdown-syntax/src/diagnostic.rs:34

--- failure enum_variant_added: enum variant added on exhaustive enum ---

Description:
A publicly-visible enum without #[non_exhaustive] has a new variant.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#enum-variant-new
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.50.0/src/lints/enum_variant_added.ron

Failed in:
  variant SerializeError:Unrepresentable in /tmp/.tmpfYoVLv/markdown-syntax/src/serialize.rs:94
  variant SerializeError:Unrepresentable in /tmp/.tmpfYoVLv/markdown-syntax/src/serialize.rs:94
  variant SerializeError:Unrepresentable in /tmp/.tmpfYoVLv/markdown-syntax/src/serialize.rs:94

--- failure enum_variant_missing: pub enum variant removed or renamed ---

Description:
A publicly-visible enum has at least one variant that is no longer available under its prior name. It may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.50.0/src/lints/enum_variant_missing.ron

Failed in:
  variant Inline::Autolink, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/ast.rs:522
  variant Inline::Autolink, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/ast.rs:522
  variant Inline::Autolink, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/ast.rs:522

--- failure struct_missing: pub struct removed or renamed ---

Description:
A publicly-visible struct cannot be imported by its prior path. A `pub use` may have been removed, or the struct itself may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.50.0/src/lints/struct_missing.ron

Failed in:
  struct markdown_syntax::ast::Autolink, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/ast.rs:787
  struct markdown_syntax::prelude::Autolink, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/ast.rs:787
  struct markdown_syntax::Autolink, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/ast.rs:787

--- failure struct_pub_field_missing: pub struct's pub field removed or renamed ---

Description:
A publicly-visible struct has at least one public field that is no longer available under its prior name. It may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.50.0/src/lints/struct_pub_field_missing.ron

Failed in:
  field preserve_character_escapes of struct ParseOptions, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/options.rs:228
  field preserve_character_references of struct ParseOptions, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/options.rs:231
  field preserve_character_escapes of struct ParseOptions, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/options.rs:228
  field preserve_character_references of struct ParseOptions, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/options.rs:231
  field preserve_character_escapes of struct ParseOptions, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/options.rs:228
  field preserve_character_references of struct ParseOptions, previously in file /tmp/.tmpcG5za3/markdown-syntax/src/options.rs:231

Changelog

0.4.0 - 2026-10-06

Added

• [breaking] rebuild block parsing and serializer escaping on one source of syntax rules (#15)

Fixed

• map spans to their source and fix CommonMark parse and round-trip defects (#12)

Migration

This release changes the AST, the parse of block structure, and the
serializer's output. Code that matches on the AST or compares canonical
output needs these updates.

• Autolinks are links. Inline::Autolink and AutolinkKind are removed.
  Literal autolinks (https://a.b, www.a.b, a@b.c), angle-bracket
  autolinks (<https://a.b>), and links whose text equals their URL are all
  Link nodes whose one child is a Text holding the URL as written. Such a
  link is written <url> when that reads back, and [text](url) otherwise
  (www.a.b → [www.a.b](http://www.a.b)).
• Escapes and character references are always nodes.
  ParseOptions::preserve_character_escapes and
  ParseOptions::preserve_character_references are removed: the parser
  always produces Inline::Escape and Inline::CharacterReference, and the
  serializer writes them as recorded. In a table cell, \| is an
  Escape('|') in text and | inside a raw-text construct.
• Wiki embeds. WikiLink gains embed: bool: ![[x]] is an embed and
  \![[x]] is an escaped ! before a plain wiki link. The HTML renderer
  marks an embed with data-wikilink-embed="true".
• Shortcodes come from gemoji. A shortcode needs a name in the pinned
  github/gemoji v4.1.0 table and no letter or digit directly outside either
  colon, so clock times and a:b:c stay text. A :word: outside the table
  stays text too: a text directive's name followed by a : opens no
  directive. Shortcode::glyph() returns the emoji, validation rejects a
  name outside the table, and the HTML renderer writes the glyph.
• Serialization reads its output back. SerializeOptions gains
  syntax: SyntaxOptions, the dialect the output is read back under (the
  maximal dialect by default). Set it to the preset you parse with: a
  CommonMark parse of a ==b== c otherwise writes a \=\=b\=\= c, since
  the maximal dialect reads == as highlight.
  SerializeError::Unrepresentable is returned, with
  DiagnosticCode::Unrepresentable, when no Markdown the serializer can
  write reads back as the same tree; an exhaustive match on
  SerializeError needs an arm for it.
• New diagnostic codes. DiagnosticCode::InvalidDirectiveAttribute
  warns about a directive attribute without a valid name, which is dropped;
  DiagnosticCode::Unrepresentable names the node serialization cannot
  write.
• Canonical output changes. Only what a parse reads as syntax is
  escaped:
  • an unpaired delimiter stays raw (x_y_, not x_y\_);
  • a pipe ending a setext heading stays raw (a |, not a \|);
  • brackets that form no reference stay raw ([x] when nothing defines
    x);
  • a delimiter run the parse uses is escaped whole (\=\=a\=\=);
  • emphasis and strong take * unless that does not read back
    (***(a b)\_.***\*#, was _**(a b)\_.**_\*#);
  • an invalid character reference such as &unknown; stays raw;
  • a nested list is indented only when the block after it would join its
    last item, and a list marker override yields where two adjacent lists
    would read as one.
• Block structure follows CommonMark's algorithm. Block quotes, list
  items, container directives, footnote definitions, HTML containers,
  description details, and alerts are read in one pass over a stack of open
  blocks, matching commonmark.js on the cases Rebuild block parsing and serializer escaping on one source of rules, and fold autolinks into Link #11
  lists. A task item's checkbox is part of its marker, so its paragraph
  starts after it. ::name text is a paragraph; a leaf directive stands alone
  on its line.
• Block parse changes that move the AST of existing input:
  • footnote definitions, directive openers, math fences, and description
    details open only up to three columns in;
  • a container directive's closing fence closes the innermost open one,
    and its last child's span ends after its line ending;
  • footnote definitions and alert paragraphs take lazy continuation lines;
  • tabs after a tab split by a container prefix keep their columns;
  • blank lines inside a fence or HTML block do not loosen a list;
  • an unclosed fence keeps its trailing blank lines;
  • a multi-line definition title drops its continuation lines'
    indentation;
  • an alert's marker line keeps a following indented line from starting
    indented code, as a paragraph line does.
• Literal autolinks end earlier. A literal or relaxed-scheme autolink
  ends at Unicode whitespace, <, a non-ASCII punctuation or symbol char
  (，, 。, 、), or, with wikilinks on, [[. parse no longer panics on
  a no-break space before an email-like run.
• A _ run gets no strikethrough bonus beside a ~: d_~_ is text.

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This PR was generated with release-plz.