Defect: an ADDED block was colored via `render(wordDiffByAuthor("", raw, ...))`, which
wrapped the whole raw markdown in an inline `<ins>` BEFORE markdown-it parsed it — so
`## X` rendered as literal text, not `<h2>`. Same structural bug for list, blockquote,
and thematic-break blocks.
Fix (three-part, pure / vscode-free):
1. `blockContentStart(raw)`: new helper returning the offset past block-level markers
(ATX headings `## `, unordered/ordered list markers, blockquotes). Open sentinels must
not precede these markers or markdown-it cannot recognise the block construct.
2. `injectSentinels`: clamp the open-sentinel lower-bound to `blockContentStart(raw)`,
so for `## New Section` the sentinel lands AFTER `## ` (at position 3) instead of at
position 0, letting the heading parse correctly.
3. `sentinelsToSpans` / `colorByAuthor`: add optional `kind: "by" | "ins" = "by"`
parameter so the sentinel path can emit `cw-ins-{author}` for added blocks while all
existing `colorByAuthor`/`cw-by-*` call-sites are unchanged.
4. `renderReview` ADDED block path: `render(wordDiffByAuthor("", raw, ...))` →
`colorByAuthor(raw, blk.start, landedSpans, render, "ins")`. The CHANGED non-atomic
prose path (`wordDiffByAuthor(before, after, ...)`) is untouched — it correctly keeps
the block markers at column 0 of the unchanged prefix.
5. `renderReviewOp`: removed the now-vestigial `colored` parameter (was always `render`
after the added-block path moved to `changedHtml`); unchanged blocks now call
`render(op.block.raw)` directly.
Regression test added: "renderReview: an added heading block renders as a heading AND
is author-colored as an insertion" — RED on old code, GREEN after fix. All 259 tests
pass; typecheck clean.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
BenStullsBets
44ef0a21db