A raw link destination escapes parentheses that are already balanced

[Azganoth]

Summary

Saving escapes every parenthesis in a raw link destination, including balanced pairs that CommonMark allows unescaped. The destination is written by the link handler rather than by the text handler #252 made precise, so the same over-escaping survives there.

Steps to reproduce

1. Open a document containing [Balanced](garden(section(one)).md).
2. Save it.
3. Read the file.

Expected behavior

[Balanced](garden(section(one)).md). A raw destination may hold balanced parentheses, so no escape is needed.

An unbalanced parenthesis still needs its escape, because it would end the destination early.

Actual behavior

Measured against 9626471d by driving the editor mount used by the plugin tests. Both rows are stable across a second save:

Document	Saved
[Balanced](garden(section(one)).md)	[Balanced](garden\(section\(one\)\).md)
[Inline script scheme](javascript:alert(1))	[Inline script scheme](javascript:alert\(1\))

Related context

• Related issues or pull requests: Preserve the authored form of a Markdown file on save #251 is the parent; The serializer escapes characters that cannot be syntax where they sit #252 made the same check precise for text and recorded this as a remaining class; test: assert corpus round-trip convergence for supported syntax #249 owns the corpus guard.
• Documentation, decisions, or prior investigation: the Outcome sections of Determine whether the Markdown corpus can drive automated round-trip tests #135 and How a Markdown escape should be represented in the editor #245, and corpus/commonmark/links-and-images.md under Balanced and unbalanced destination parentheses.

Done when

• A balanced pair of parentheses in a raw destination saves without an escape.
• An unbalanced parenthesis keeps its escape, and a destination that would need one either keeps it or switches to the angle-bracket form.
• Regression coverage asserts both directions.

Notes, logs, screenshots

Diagnosis

The escapes come from {character: '(', inConstruct: 'destinationRaw'} and {character: ')', inConstruct: 'destinationRaw'} in mdast-util-to-markdown's core unsafe list, applied while the link handler serializes the destination. serializeMarkdownText in src/features/editor/utils/markdownText.ts never sees it, and its relaxBracketEscapes pass is scoped to phrasing parents specifically to stay out of this construct.

Implementation direction

Whether a destination needs escaping is a property of the whole destination rather than of one character, so the natural seam is a link and image handler override alongside the existing text one in createMilkdownEditor.ts, not the character-level pass in markdownText.ts.

mdast-util-to-markdown already chooses between the raw and angle-bracket destination forms, so switching form is an available answer for a destination that cannot be written raw, and may be simpler than escaping selectively.

Out of scope

• The \( written after a ] in ordinary text, which The serializer escapes characters that cannot be syntax where they sit #252 already fixed.
• Character-reference destinations being decoded on load, which is filed on its own.