Move paragraph/heading textAlign off the HTML-wrapper form
(<p style="text-align:…"> / <hN style=…>) onto a trailing attached HTML
comment on the block line: `text <!--attrs {"textAlign":"center"}-->`. This
keeps the readable markdown block form (plain `text` / `## Title`) while
preserving alignment losslessly. "left"/null stay bare (no churn).
Adds a reusable attached-comment primitive (attached-comment.ts) that #4
(image) and #8 (media) will reuse:
- attachedCommentFor(name, json) -> `<!--name {compact-json}-->`, escaping any
`--` pair inside the JSON as -- so the payload can never close the
comment early;
- parseAttachedComment(data) with grammar `^\s*([A-Za-z][\w-]*)(?:\s+({…}))?\s*$`
whose name excludes `:`, so envelope comments (docmost:meta / docmost:comments)
never match — fail-open on anything malformed.
On import, applyAttachedComments runs AFTER marked.parse but BEFORE generateJSON
(parse5 drops comments), re-expressing the attrs comment as an inline
text-align style on the parent block, then removing the comment node.
Guards: emit only when there is a visible element to attach to — paragraph
requires non-empty text, heading requires non-empty headingText (symmetry:
an empty aligned heading stays bare `##`, no orphan comment).
Goldens in markdown-converter-golden/gaps updated deliberately to the
attached-comment form (assertions stay strict: exact output + lossless
round-trip). New textalign.test.ts (19 tests) covers center/right/justify on
paragraph and heading, byte-stable re-export, and fail-open branches.
Raw-HTML containers (columns/cells/callout via blockToHtml) keep the inline
text-align form intentionally — comments are dropped inside raw HTML.
package vitest: 462 passed | 1 expected-fail; tsc clean. git-sync: 268 passed.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
claude code agent 227