* fix(#1779): emit valid YAML for unsafe scalars in reconstructFrontmatter
reconstructFrontmatter wraps a scalar or block-array item in double quotes
when it contains a YAML indicator (`:`/`#`, plus `[`/`{` for top-level
scalars), but interpolated the raw value with no escaping. A value carrying
both an indicator and a literal `"` (or `\`) serialized to invalid YAML, e.g.
`upstream: "https://x (Tom; "Git. Ship. Done")"`, which fails under any strict
parser (js-yaml, PyYAML) and corrupts the whole block on the next
syncStateFrontmatter whole-block regen.
- escapeDoubleQuoted() escapes `\`, `"`, and control chars (newline/tab/CR/C0
controls + DEL → YAML `\n`/`\t`/`\r`/`\xHH`) so any wrapped value is valid.
- scalarNeedsDoubleQuoting() routes values that mis-parse or round-trip lossily
when bare through that escaped form: the empty string (bare `k:` reloads as
null), an embedded `"`/`\` or control char, a leading YAML indicator
(quote / `&`*`!` anchor-alias-tag / `|`>` block scalar / flow `[]{},` / `#` /
reserved `%`@`backtick / `-`?`:` before a space), or leading/trailing space.
Applied at all four wrap sites.
Scope stays on serialization correctness; it does NOT broaden the lossy
object-list handling deferred to #1572/#1660. Known limitation: lone UTF-16
surrogates are still lossy through UTF-8 encoding (out of scope, extremely
unlikely in frontmatter values).
Regression test asserts strict js-yaml round-trip across all four wrap sites
plus backslash, control-char (incl. NUL), empty-string, leading-indicator, and
leading/trailing-whitespace classes; test-the-test confirms each fails on the
unescaped output. Frontmatter suite 549/549 green, golden-install-parity 16/16
unchanged (no serialization churn).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* chore(#1779): add changeset for frontmatter quote-escaping fix
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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