docs(web): correct the fence-meta example and pin the later-line trailing shape

.agents/notes/implemented/bug-fix/2026-09-17-multiline-display-dollar-math.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/bug-fix/2026-09-17-multiline-display-dollar-math.md
-2026-09-17-multiline-display-dollar-math.md: 5346951c52d83233ce863754623b7721e5e99c00
-2026-09-17-multiline-display-dollar-math.zh.md: 4b11f196638a1184b4d9082f36df903ca1ccaab8
+2026-09-17-multiline-display-dollar-math.md: 03628953148f157a15447b7e83fea9525c5e3149
+2026-09-17-multiline-display-dollar-math.zh.md: ed0ef3f46a2b5232f7c585175dcad4de6ebb9974

.agents/notes/implemented/bug-fix/2026-09-17-multiline-display-dollar-math.md

@@ -45,7 +45,7 @@ Its paragraph-interruption check declines instead of consuming the line ending,
 
 ## Consequences
 
-The three shapes now produce the same math node, so formulas stop truncating at the opening line and stop swallowing the prose after them. `$$` fence meta is no longer honored: `$$asciimath` parses as a formula whose first line is `asciimath`, which upstream's flow would have split into meta plus body. That spelling has no user in this repository, and the renderer never read `meta` anyway.
+The three shapes now produce the same math node, so formulas stop truncating at the opening line and stop swallowing the prose after them. `$$` fence meta is no longer honored: `$$asciimath$$` parses as a formula whose value is `asciimath`, which upstream's flow treats as fence meta and drops. That spelling has no user in this repository, and the renderer never read `meta` anyway.
 
 Six inputs still reach upstream's flow or stay in the surrounding paragraph, because the compatibility flow declines them. Trailing text after a closing `$$` (`$$x$$ trailing`, or a CJK quote mark closing a line of prose) resolves through upstream inline math, as the existing `markdown.client.spec.tsx` case pins — including when a later `$$` block follows. A `$$` sequence the line does not end after declines the block: immediately on a later line, and at that line's ending on the opening line. A `$$` block left open runs to the next lone `$$` or to EOF exactly as it did before this change, because the upstream flow closes at EOF.
 
@@ -61,6 +61,6 @@ Repeated unclosed candidates keep linear parser work: an open candidate declines
 
 ## Testing
 
-`packages/client/ui-primitives/tests/markdown.client.spec.tsx` adds the multi-line case — opening-line math closed on a content line, closed by a lone fence, after a paragraph, inside a list item, and at column zero after a list item — and that case fails without the change. The same file also pins a multi-line formula that uses a solitary `$`, which like the case above renders only with this change. Further cases pin one condition each: a trailing-text candidate ahead of a later block (the flow must decline a full `$$` the line does not end after), a solitary `$` inside a single-line display formula (the flow must not decline on a single `$`), an escaped-dollar candidate that leaves its paragraph intact (the interruption check must not claim the paragraph), an unclosed `\[` candidate that leaves its paragraph intact (the guard must not apply to the backslash construct), a candidate ending in an odd backslash (the escape run must end at the line ending), a closing fence inside a TeX comment, a `%` the fence follows immediately or after whitespace, a second `%` inside an open comment, a `%` inside `\verb|…|`, the delimiter right after `\verb` and `\verb*` together with its empty region, an escaped backslash before `verb`, a verb tail that crosses no line ending, a comment ending in `verb`, a failed fence inside a comment, and bounded-work cases for repeated candidates with that backslash, without it, and ending in a verb tail.
+`packages/client/ui-primitives/tests/markdown.client.spec.tsx` adds the multi-line case — opening-line math closed on a content line, closed by a lone fence, after a paragraph, inside a list item, and at column zero after a list item — and that case fails without the change. The same file also pins a multi-line formula that uses a solitary `$`, which like the case above renders only with this change. Further cases pin one condition each: a trailing-text candidate ahead of a later block (the flow must decline a full `$$` the line does not end after), a solitary `$` inside a single-line display formula (the flow must not decline on a single `$`), an escaped-dollar candidate that leaves its paragraph intact (the interruption check must not claim the paragraph), an unclosed `\[` candidate that leaves its paragraph intact (the guard must not apply to the backslash construct), a candidate ending in an odd backslash (the escape run must end at the line ending), a closing fence inside a TeX comment, a `%` the fence follows immediately or after whitespace, a second `%` inside an open comment, a `%` inside `\verb|…|`, the delimiter right after `\verb` and `\verb*` together with its empty region, an escaped backslash before `verb`, a verb tail that crosses no line ending, a comment ending in `verb`, a later-line trailing fence whose following prose upstream takes, a failed fence inside a comment, and bounded-work cases for repeated candidates with that backslash, without it, and ending in a verb tail.
 
 The DOM compatibility corpus adds `math-multiline-display` with its `.settled.txt` and `.streaming.txt` fixtures, which also pin that a column-zero `$$` after a list item stays outside the list item. `apps/web/tests/math-rendering.e2e.ts` renders the multi-line shape in the browser lane.

.agents/notes/implemented/bug-fix/2026-09-17-multiline-display-dollar-math.zh.md

@@ -45,7 +45,7 @@ $$f(x)=x
 
 ## Consequences
 
-三种写法现在产生同一个 math 节点，公式不再在开围栏那一行被截断，也不再吞掉其后的正文。`$$` 围栏 meta 不再生效：`$$asciimath` 会解析成首行为 `asciimath` 的公式，而上游 flow 会把它拆成 meta 加正文。这种写法在本仓库没有使用者，且渲染器本来就从不读 `meta`。
+三种写法现在产生同一个 math 节点，公式不再在开围栏那一行被截断，也不再吞掉其后的正文。`$$` 围栏 meta 不再生效：`$$asciimath$$` 会解析成 value 为 `asciimath` 的公式，而上游 flow 会把该段当作 fence meta 丢弃。这种写法在本仓库没有使用者，且渲染器本来就从不读 `meta`。
 
 有六种输入仍会走到上游 flow，或留在所属段落里，因为兼容 flow 主动放弃它们。闭合 `$$` 之后还有文本时（`$$x$$ trailing`，或用中文引号收尾的散文行）走上游行内数学，这一点由 `markdown.client.spec.tsx` 中已有用例固定，后面还有别的 `$$` 块时同样如此。「后面不是行尾」的 `$$` 序列会让块放弃：出现在后续行时立即放弃，出现在开围栏行时在该行行尾放弃。未闭合的 `$$` 块仍像本次改动之前那样延伸到下一个独占行 `$$` 或文件结尾，因为上游 flow 在 EOF 处闭合。
 
@@ -61,6 +61,6 @@ $$f(x)=x
 
 ## Testing
 
-`packages/client/ui-primitives/tests/markdown.client.spec.tsx` 新增多行用例——开围栏行内容由内容行行尾 `$$` 闭合、由独占行 `$$` 闭合、出现在段落之后、出现在列表项内，以及列表项之后的零缩进围栏——该用例去掉改动即失败。同一文件还固定了「使用单个 `$` 的多行公式」，它与上面的多行用例一样只有本次改动才会渲染成 display。另有一组用例各自对应一个条件：后面还有块时的尾随文本候选（flow 必须放弃「后面不是行尾」的完整 `$$`）、单行显示公式内的单个 `$`（不得因为一个 `$` 就放弃）、保持段落完整性的转义美元候选（打断检查不得认领段落）、保持段落完整性的未闭合 `\[` 候选（守卫不得作用于反斜杠构造）、以奇数个反斜杠结尾的候选（转义状态必须在换行处结束）、TeX 注释内的闭合围栏、紧邻围栏或只隔空白的 `%`、已开启注释内的第二个 `%`、`\verb|…|` 内的 `%`、`\verb` 与 `\verb*` 之后的分隔符及其空区域、`verb` 之前的转义反斜杠、不跨行的 verb 尾部、以 `verb` 结尾的注释、注释内失败的围栏，以及带该反斜杠、不带该反斜杠、以 verb 尾部结尾三种重复候选的有界解析开销。
+`packages/client/ui-primitives/tests/markdown.client.spec.tsx` 新增多行用例——开围栏行内容由内容行行尾 `$$` 闭合、由独占行 `$$` 闭合、出现在段落之后、出现在列表项内，以及列表项之后的零缩进围栏——该用例去掉改动即失败。同一文件还固定了「使用单个 `$` 的多行公式」，它与上面的多行用例一样只有本次改动才会渲染成 display。另有一组用例各自对应一个条件：后面还有块时的尾随文本候选（flow 必须放弃「后面不是行尾」的完整 `$$`）、单行显示公式内的单个 `$`（不得因为一个 `$` 就放弃）、保持段落完整性的转义美元候选（打断检查不得认领段落）、保持段落完整性的未闭合 `\[` 候选（守卫不得作用于反斜杠构造）、以奇数个反斜杠结尾的候选（转义状态必须在换行处结束）、TeX 注释内的闭合围栏、紧邻围栏或只隔空白的 `%`、已开启注释内的第二个 `%`、`\verb|…|` 内的 `%`、`\verb` 与 `\verb*` 之后的分隔符及其空区域、`verb` 之前的转义反斜杠、不跨行的 verb 尾部、以 `verb` 结尾的注释、后续行尾随文本围栏（其后正文由上游接管）、注释内失败的围栏，以及带该反斜杠、不带该反斜杠、以 verb 尾部结尾三种重复候选的有界解析开销。
 
 DOM 兼容语料新增 `math-multiline-display` 及其 `.settled.txt`、`.streaming.txt`，同时固定了「列表项之后的零缩进 `$$` 不进入列表项内」。`apps/web/tests/math-rendering.e2e.ts` 在浏览器 lane 渲染多行写法。

packages/client/ui-primitives/tests/markdown.client.spec.tsx

@@ -651,6 +651,14 @@ describe('MarkdownText', () => {
     unterminated.unmount()
   })
 
+  it('leaves a later-line trailing fence to upstream, which takes the following prose', () => {
+    const { container } = render(<MarkdownText text={'$$a+b\nc+d$$ trailing\n\nAfter'} />)
+
+    expect(container.querySelectorAll('p')).toHaveLength(0)
+    expect(container.querySelector('.katex-error')?.textContent).toContain('c+d$$ trailing')
+    expect(container.textContent).toContain('After')
+  })
+
   it('does not read a comment ending in verb as a verbatim delimiter', () => {
     const { container } = render(<MarkdownText text={'$$x % \\verb$$\n\nAfter\n\n$$\ny\n$$'} />)