fix(editor): persist a dragged table column width as a sidecar marker

[h4yfans]

Closes #1936. Part of #1934.

Why

Resizing a table column works, and nothing carries the result out of the session. BlockNote keeps a dragged width in the table content's columnWidths, GFM has no syntax for it, and blocksToMarkdownLossy writes | a | b |, so the width is gone the next time the note is parsed. Markdown is the storage, so the width needs somewhere on disk to live.

It goes next to the table as a comment line, the same shape the cell colour marker already uses. #1937 turned that pattern into a registry in packages/shared/src/block-markers.ts, and both serializers read and write through it, so this is a fourth registry entry rather than a fourth pair of code paths. Living in the note body also means the width syncs with the note, with no new synced type and no device-local state to go stale.

Scope

packages/shared/src/block-markers.ts gains TableLayout, extractTableLayout, serializeTableLayoutMarker, parseTableLayoutMarker and applyTableLayout, plus the registry entry that puts the marker after table-colors in on-disk order.

<!-- table-layout:{"columnWidths":[120,null]} -->
| Name | Status |
| ---- | ------ |
| Ship | Done   |

One slot per column. A column nobody has resized is null, and a table whose slots are all null writes no marker, so a table already in a vault keeps its bytes.

On read the parsed table's own column count wins, not the marker's. A marker naming fewer columns is padded with the widths BlockNote chose, one naming more is truncated. A columnWidths that is not an array of positive finite numbers or nulls is not claimed as a marker at all and stays a foreign comment.

Row heights are out, and not by omission. BlockNote's table content holds columnWidths, headerRows and headerCols, and nothing about row sizes, so there is no row height in the block model to persist. The issue title names both; only the column half exists to fix.

Tradeoffs

The width is visible to anyone reading the raw .md. The alternative, a per-note view-state record beside the note, keeps the file clean but makes the width device-local until it becomes a synced type, and leaves it to go stale when the table is edited. The marker travels with the note for free and reconciles against the table it sits above.

An older app version reading a marked file drops the comment on its next save and shows the table at default widths, which is the same degrade the colour and alignment markers already have.

Blast Radius

Both serializers, for tables only. A table nobody has resized writes no marker, so no note in any existing vault changes bytes on its next save; the golden vault fixture holds an untouched table next to a marked one to keep that true. The registry entry is additive, so the colour and alignment markers keep their bytes and their order.

apps/mobile/src/editor/generated/editor-web-asset.ts is a rebuild, not an edit. editor:check stamps the packed bundle against its sources and the shared registry is one of them.

Verification

pnpm --filter @memry/desktop test:main on blocknote-converter.test.ts, 6 of the 6 new #1936 cases green. With the registry entry removed by hand, 5 of the 6 go red and the "leaves a table nobody has resized byte-identical" guard stays green, which is the shape the fix should have.

Round-trip conformance and the golden vault on both pipelines: blocknote-converter.roundtrip.test.ts and byte-preservation.golden.test.ts 131 passed, renderer markdown-utils.test.ts and roundtrip-conformance.test.ts 114 passed with the 2 pre-existing expected failures. --project shared 2764 passed.

E2E table-column-widths-persist.e2e.ts green in 19.5s against a production build: drag the width, wait for the marker to reach the vault file, switch to another note and back, relaunch the app, then measure the rendered header cell so a width that reaches the block model but never reaches the layout still fails. This is the one check here that walks the whole user-facing path.

pnpm typecheck and pnpm lint clean. pnpm docs:impact --base origin/main --strict reports covered, pnpm docs:build builds.

[github-actions]

React Doctor found no new issues. 🎉

_{Reviewed by React Doctor for commit 90d22b3.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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