From 914b81c54b16d9e4306f88982fe3857905ceeaf9 Mon Sep 17 00:00:00 2001
From: Divyansh Singh <40380293+brc-dd@users.noreply.github.com>
Date: Sun, 30 Aug 2026 20:37:23 +0530
Subject: [PATCH] feat: resolve `$frontmatter` expressions while rendering
 markdown

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../e2e/local-search/frontmatter-title.md     |   7 +
 .../e2e/local-search/local-search.test.ts     |  22 ++
 __tests__/unit/node/markdown/markdown.test.ts |   8 +
 .../plugins/frontmatterExpressions.test.ts    | 239 ++++++++++++++++
 docs/en/guide/frontmatter.md                  |   2 +
 src/node/markdown/markdown.ts                 |  19 ++
 .../plugins/frontmatterExpressions.ts         | 256 ++++++++++++++++++
 7 files changed, 553 insertions(+)
 create mode 100644 __tests__/e2e/local-search/frontmatter-title.md
 create mode 100644 __tests__/unit/node/markdown/plugins/frontmatterExpressions.test.ts
 create mode 100644 src/node/markdown/plugins/frontmatterExpressions.ts

diff --git a/__tests__/e2e/local-search/frontmatter-title.md b/__tests__/e2e/local-search/frontmatter-title.md
new file mode 100644
index 00000000..0000a15b
--- /dev/null
+++ b/__tests__/e2e/local-search/frontmatter-title.md
@@ -0,0 +1,7 @@
+---
+title: Frontmatter Title Resolved
+---
+
+# {{ $frontmatter.title }}
+
+This page uses a frontmatter title expression.
diff --git a/__tests__/e2e/local-search/local-search.test.ts b/__tests__/e2e/local-search/local-search.test.ts
index fe507e5b..463dd87a 100644
--- a/__tests__/e2e/local-search/local-search.test.ts
+++ b/__tests__/e2e/local-search/local-search.test.ts
@@ -83,6 +83,28 @@ describe('local search', () => {
     ).toBe(0)
   })
 
+  test('resolves $frontmatter expressions in search results', async () => {
+    await page.locator('.VPNavBarSearchButton').click()
+
+    const input = await page.waitForSelector('input#localsearch-input')
+    await input.type('Frontmatter Title Resolved')
+
+    const searchResults = page.locator('#localsearch-list')
+    await page.waitForFunction(() => {
+      return document.querySelectorAll('#localsearch-list li[role=option]')
+        .length
+    })
+
+    expect(
+      await searchResults
+        .filter({ hasText: 'Frontmatter Title Resolved' })
+        .count()
+    ).toBe(1)
+    expect(
+      await searchResults.filter({ hasText: '$frontmatter.title' }).count()
+    ).toBe(0)
+  })
+
   test('custom tokenize function reaches the client', async () => {
     await page.locator('.VPNavBarSearchButton').click()
 
diff --git a/__tests__/unit/node/markdown/markdown.test.ts b/__tests__/unit/node/markdown/markdown.test.ts
index 5db12abd..76063dac 100644
--- a/__tests__/unit/node/markdown/markdown.test.ts
+++ b/__tests__/unit/node/markdown/markdown.test.ts
@@ -42,6 +42,14 @@ describe('node/markdown/markdown', () => {
       expect(await render(':tada:', { emoji: false })).toContain(':tada:')
     })
 
+    test('frontmatterExpressions', async () => {
+      const src = '---\ntitle: Hello\n---\n\n{{ $frontmatter.title }}'
+      expect(await render(src)).toContain('<p>Hello</p>')
+
+      const disabled = await render(src, { frontmatterExpressions: false })
+      expect(disabled).toContain('<p>{{ $frontmatter.title }}</p>')
+    })
+
     test('tasklist', async () => {
       const src = '- [ ] todo'
       expect(await render(src)).toContain('<input type="checkbox"')
diff --git a/__tests__/unit/node/markdown/plugins/frontmatterExpressions.test.ts b/__tests__/unit/node/markdown/plugins/frontmatterExpressions.test.ts
new file mode 100644
index 00000000..8a3b61c3
--- /dev/null
+++ b/__tests__/unit/node/markdown/plugins/frontmatterExpressions.test.ts
@@ -0,0 +1,239 @@
+import {
+  createMarkdownRenderer,
+  disposeMdItInstance,
+  type MarkdownOptions
+} from 'node/markdown/markdown'
+// the full build, for compiling templates the way the Vue plugin would
+// @ts-expect-error no types for dist builds
+import { createSSRApp } from 'vue/dist/vue.cjs.js'
+import { renderToString } from 'vue/server-renderer'
+
+async function createMd(options: MarkdownOptions = {}) {
+  disposeMdItInstance()
+  return createMarkdownRenderer('.', { highlight: (code) => code, ...options })
+}
+
+async function render(src: string, env: Record<string, any> = {}) {
+  return (await createMd()).renderAsync(src, env)
+}
+
+const frontmatter = `\
+---
+title: Hello World
+count: 5
+flag: true
+nothing: null
+date: 2024-01-18
+html: '<b>&amp; {{ hi }}</b>'
+mustache: '{{ x }}'
+k-y: dashed
+spaced: 'a  b'
+multiline: |
+  line one
+  line two
+homepage: https://vitepress.dev/
+nested:
+  deep: value
+list:
+  - a
+  - b
+---
+
+`
+
+async function renderBody(body: string) {
+  return (await render(frontmatter + body)).trim()
+}
+
+describe('node/markdown/plugins/frontmatterExpressions', () => {
+  test('resolves property paths and escapes the value', async () => {
+    const html = await render(`\
+---
+meta:
+  title: A <b>& B
+count: 2
+done: false
+---
+
+{{ $frontmatter.meta.title }} / {{$frontmatter.count}} / {{ $frontmatter.done }}
+`)
+    expect(html).toContain('<p>A &lt;b&gt;&amp; B / 2 / false</p>')
+  })
+
+  test('resolves bracket paths and dates', async () => {
+    expect(await renderBody("{{ $frontmatter['k-y'] }}")).toBe('<p>dashed</p>')
+    expect(await renderBody('{{ $frontmatter["k-y"] }}')).toBe('<p>dashed</p>')
+    expect(await renderBody('{{ $frontmatter.list[1] }}')).toBe('<p>b</p>')
+    expect(await renderBody('{{ $frontmatter.list.length }}')).toBe('<p>2</p>')
+    // dates are normalized the same way the `__pageData` JSON round-trip
+    // normalizes them for the runtime
+    expect(await renderBody('{{ $frontmatter.date }}')).toBe(
+      '<p>2024-01-18T00:00:00.000Z</p>'
+    )
+  })
+
+  test('escapes values so they render as this exact text', async () => {
+    expect(await renderBody('{{ $frontmatter.html }}')).toBe(
+      '<p>&lt;b&gt;&amp;amp; &#123;&#123; hi &#125;&#125;&lt;/b&gt;</p>'
+    )
+    // a value containing mustaches must not be interpolated again by Vue
+    expect(await renderBody('{{ $frontmatter.mustache }}')).toBe(
+      '<p>&#123;&#123; x &#125;&#125;</p>'
+    )
+    expect(
+      await renderBody(
+        '&copy; {{ $frontmatter.title }} / {{ $frontmatter.no }}'
+      )
+    ).toBe('<p>&copy; Hello World / {{ $frontmatter.no }}</p>')
+  })
+
+  test('leaves everything else to Vue', async () => {
+    const expressions = [
+      '{{ $frontmatter.missing }}', // key not in frontmatter
+      '{{ $frontmatter.title.length }}', // path through a non-object
+      '{{ $frontmatter.nothing.x }}',
+      '{{ $frontmatter.nothing }}', // renders '' but may be transformed later
+      '{{ $frontmatter }}',
+      '{{ $frontmatter.nested }}', // objects are for Vue's display formatting
+      '{{ $frontmatter.list }}',
+      '{{ $frontmatter.spaced }}', // double space would be condensed
+      '{{ $frontmatter.multiline }}',
+      '{{ $frontmatter.list[01] }}',
+      '{{ $frontmatter.title.toUpperCase() }}',
+      '{{ $frontmatter[title] }}',
+      '{{ $frontmatterX }}',
+      '{{ $params.id }}',
+      '{{ frontmatter.title }}'
+    ]
+    const html = await renderBody(expressions.join('\n\n'))
+    for (const expression of expressions) {
+      expect(html).toContain(`<p>${expression}</p>`)
+    }
+  })
+
+  test('skips code and v-pre', async () => {
+    const html = await render(`\
+---
+title: Hi
+---
+
+\`{{ $frontmatter.title }}\`
+
+\`\`\`js
+{{ $frontmatter.title }}
+\`\`\`
+
+::: v-pre
+{{ $frontmatter.title }}
+:::
+
+<span v-pre>{{ $frontmatter.title }}</span> {{ $frontmatter.title }}
+`)
+    expect(html.match(/\{\{ \$frontmatter\.title \}\}/g)).toHaveLength(4)
+    expect(html).toContain('</span> Hi</p>')
+  })
+
+  test('skips v-pre scopes from attrs', async () => {
+    const html = await renderBody(
+      '**{{ $frontmatter.title }}**{v-pre} {{ $frontmatter.title }}'
+    )
+    expect(html).toContain(
+      '<strong v-pre="">{{ $frontmatter.title }}</strong> Hello World'
+    )
+  })
+
+  test('stops at v-pre html blocks', async () => {
+    const html = await renderBody(
+      '{{ $frontmatter.title }}\n\n<div v-pre>\n\n{{ $frontmatter.title }}\n\n</div>'
+    )
+    // content before the block cannot be inside its scope
+    expect(html).toContain('<p>Hello World</p>')
+    expect(html).toContain('<p>{{ $frontmatter.title }}</p>')
+  })
+
+  test('feeds the resolved text to anchors and the page title', async () => {
+    const env: Record<string, any> = {}
+    const html = await render(
+      `\
+---
+title: Hello World
+---
+
+# {{ $frontmatter.title }}
+`,
+      env
+    )
+    expect(html).toContain('id="hello-world"')
+    expect(env.title).toBe('Hello World')
+  })
+
+  test('resolves link and image destinations', async () => {
+    const html = await renderBody(
+      [
+        '[home]({{$frontmatter.homepage}})',
+        '[docs](<{{ $frontmatter.homepage }}>)',
+        '[nope]({{$frontmatter.nope}})'
+      ].join('\n\n')
+    )
+    expect(html).toContain('href="https://vitepress.dev/"')
+    // external link handling applies to the resolved destination
+    expect(html).toContain('target="_blank"')
+    // unresolvable destinations keep their expression
+    expect(html).toContain('$frontmatter.nope')
+  })
+
+  test('resolves image sources', async () => {
+    const html = await render(`\
+---
+logo: /logo.png
+---
+
+![logo]({{$frontmatter.logo}})
+`)
+    expect(html).toContain('src="/logo.png"')
+  })
+
+  test('leaves everything alone without frontmatter data', async () => {
+    expect((await render('{{ $frontmatter.title }}')).trim()).toBe(
+      '<p>{{ $frontmatter.title }}</p>'
+    )
+  })
+
+  describe('equivalence with runtime interpolation', () => {
+    async function ssr(html: string, $frontmatter: unknown) {
+      const app = createSSRApp({ template: `<div>${html}</div>` })
+      app.config.globalProperties.$frontmatter = $frontmatter
+      app.config.warnHandler = () => {}
+      return renderToString(app)
+    }
+
+    test('inlined values render exactly what the runtime would', async () => {
+      const body = [
+        'Welcome to {{ $frontmatter.title }}!',
+        '{{ $frontmatter.html }}',
+        '{{ $frontmatter.mustache }}',
+        '{{ $frontmatter.count }} / {{ $frontmatter.flag }}',
+        '{{ $frontmatter.date }}',
+        'a  {{$frontmatter.title}}  b' // whitespace condensing parity
+      ].join('\n\n')
+
+      const runtimeEnv: any = {}
+      const runtimeMd = await createMd({ frontmatterExpressions: false })
+      const runtimeHtml = await runtimeMd.renderAsync(
+        frontmatter + body,
+        runtimeEnv
+      )
+      const resolvedHtml = await (
+        await createMd()
+      ).renderAsync(frontmatter + body, {})
+      expect(resolvedHtml).not.toContain('$frontmatter')
+
+      // the runtime sees the frontmatter after the `__pageData` JSON
+      // round-trip; the resolved template must not need it at all
+      const runtimeData = JSON.parse(JSON.stringify(runtimeEnv.frontmatter))
+      expect(await ssr(resolvedHtml, { poisoned: true })).toBe(
+        await ssr(runtimeHtml, runtimeData)
+      )
+    })
+  })
+})
diff --git a/docs/en/guide/frontmatter.md b/docs/en/guide/frontmatter.md
index dc205816..e8dd329a 100644
--- a/docs/en/guide/frontmatter.md
+++ b/docs/en/guide/frontmatter.md
@@ -36,6 +36,8 @@ editLink: true
 Guide content
 ```
 
+Property accesses like `{{ $frontmatter.title }}` are resolved while the Markdown is rendered, so the value also ends up in the local search index, in [content loader](./data-loading#createcontentloader) output, in heading anchors - the heading above gets `id="docs-with-vitepress"` - and in link targets written without spaces around the expression, like `[text]({{$frontmatter.link}})`. Other expressions are evaluated by Vue at runtime as usual, and wrapping an expression in [`v-pre`](./using-vue#escaping) shows it literally.
+
 You can also access current page's frontmatter data in `<script setup>` with the [`useData()`](../reference/runtime-api#usedata) helper.
 
 ## Alternative Frontmatter Formats
diff --git a/src/node/markdown/markdown.ts b/src/node/markdown/markdown.ts
index 84886d3d..8eb5cbde 100644
--- a/src/node/markdown/markdown.ts
+++ b/src/node/markdown/markdown.ts
@@ -51,6 +51,7 @@ import {
   gitHubAlertsPlugin,
   type ContainerOptions
 } from './plugins/containers'
+import { frontmatterExpressionsPlugin } from './plugins/frontmatterExpressions'
 import { highlight as createHighlighter } from './plugins/highlight'
 import { imagePlugin, type Options as ImageOptions } from './plugins/image'
 import {
@@ -326,6 +327,21 @@ export interface MarkdownOptions extends MarkdownItAsyncOptions {
    * @see https://github.com/mdit-vue/mdit-vue/tree/main/packages/plugin-frontmatter
    */
   frontmatter?: FrontmatterPluginOptions
+  /**
+   * Resolve `{{ $frontmatter.<path> }}` interpolations to their values while
+   * rendering markdown, so the value also reaches consumers that never run
+   * Vue - heading anchors and titles, the local search index, content loader
+   * output, link destinations - and the compiled Vue template gets static
+   * text instead of a runtime expression. Only bare property paths resolving
+   * to simple primitive values in the page's own frontmatter are inlined -
+   * anything else (complex expressions, missing keys, non-primitive values,
+   * `v-pre` scopes) keeps its runtime interpolation. Set to `false` to leave
+   * all interpolation to the Vue runtime.
+   *
+   * @experimental
+   * @default true
+   */
+  frontmatterExpressions?: boolean
   /**
    * Options for `@mdit-vue/plugin-sfc`.
    * @see https://github.com/mdit-vue/mdit-vue/tree/main/packages/plugin-sfc
@@ -537,6 +553,9 @@ export async function createMarkdownRenderer(
   // https://github.com/jonschlinkert/gray-matter/blob/310f9349381775d10a221cef903989eb5acc8843/index.js#L44-L47
   ;(options.frontmatter ??= {}).grayMatterOptions ??= {}
   frontmatterPlugin(md, options.frontmatter)
+  if (options.frontmatterExpressions !== false) {
+    frontmatterExpressionsPlugin(md)
+  }
   if (options.headers) {
     headersPlugin(md, {
       level: [2, 3, 4, 5, 6],
diff --git a/src/node/markdown/plugins/frontmatterExpressions.ts b/src/node/markdown/plugins/frontmatterExpressions.ts
new file mode 100644
index 00000000..a7efb8e5
--- /dev/null
+++ b/src/node/markdown/plugins/frontmatterExpressions.ts
@@ -0,0 +1,256 @@
+import type { MarkdownItAsync } from 'markdown-it-async'
+import type StateCore from 'markdown-it/lib/rules_core/state_core.mjs'
+import type Token from 'markdown-it/lib/token.mjs'
+
+import type { MarkdownEnv } from '../../shared'
+
+// matches an interpolation the way Vue's template parser does: from `{{` up
+// to the nearest `}}`
+const interpolationRE = /\{\{([^]+?)\}\}/g
+
+// the same inside a link destination - markdown-it percent-encodes
+// destinations while tokenizing, so the delimiters may appear encoded
+const destInterpolationRE = /(?:\{\{|%7B%7B)([^]*?)(?:\}\}|%7D%7D)/gi
+
+// a statically resolvable path after `$frontmatter`: any number of `.key`,
+// `[<index>]`, `['<key>']` or `["<key>"]` segments. Leading-zero indices and
+// string escapes are excluded - the runtime handles those. Keep both
+// expressions in sync.
+const pathRE =
+  /^(?:\s*(?:\.\s*[A-Za-z_$][\w$]*|\[\s*(?:0|[1-9]\d*|'[^'\\]*'|"[^"\\]*")\s*\]))*$/
+const segmentRE =
+  /\.\s*([A-Za-z_$][\w$]*)|\[\s*(?:(0|[1-9]\d*)|'([^'\\]*)'|"([^"\\]*)")\s*\]/g
+
+// an opening html tag carrying `v-pre`, e.g. `<span v-pre>`, and the tag
+// name of any html tag, for tracking where that scope ends
+const vPreOpenRE = /^<[A-Za-z][\w-]*\s[^>]*(?<=\s)v-pre(?=[\s=/>])/
+const htmlTagRE = /^<(\/?)([A-Za-z][\w-]*)/
+const vPreRE = /\bv-pre\b/
+
+type Resolve = (expr: string) => string | undefined
+
+export const frontmatterExpressionsPlugin = (md: MarkdownItAsync) => {
+  // before the rules other plugins push (anchor, toc, ...), so slugs and
+  // extracted titles are derived from the resolved text
+  md.core.ruler.after('text_join', 'vp_frontmatter_expressions', (state) =>
+    frontmatterExpressions(md, state)
+  )
+
+  // resolved values render with their own escaping (see `escapeValue`);
+  // everything else keeps the existing text rule
+  const textRule = md.renderer.rules.text!
+  md.renderer.rules.text = (tokens, idx, options, env, self) =>
+    tokens[idx].meta?.frontmatterValue
+      ? escapeValue(tokens[idx].content)
+      : textRule(tokens, idx, options, env, self)
+}
+
+function frontmatterExpressions(md: MarkdownItAsync, state: StateCore): void {
+  const { frontmatter } = state.env as MarkdownEnv
+  if (!frontmatter || !state.src.includes('{{')) return
+
+  // the runtime `$frontmatter` is the frontmatter after the JSON round-trip
+  // into `__pageData` (see `injectPageDataCode`), so resolve against the
+  // same view of the data - dates become ISO strings and non-JSON values
+  // are dropped
+  let data: unknown
+  let failed = false
+  const resolve: Resolve = (rawExpr) => {
+    const expr = rawExpr.trim()
+    if (!expr.startsWith('$frontmatter')) return undefined
+    const path = expr.slice('$frontmatter'.length)
+    if (!pathRE.test(path)) return undefined
+
+    if (data === undefined && !failed) {
+      try {
+        data = JSON.parse(JSON.stringify(frontmatter))
+      } catch {
+        failed = true
+      }
+    }
+    if (failed) return undefined
+
+    let value = data
+    for (const m of path.matchAll(segmentRE)) {
+      const key = (m[1] ?? m[2] ?? m[3] ?? m[4])!
+      // a missing key may still be provided by `transformPageData`, and a
+      // path through a non-object would throw at runtime - leave both alone
+      if (
+        value === null ||
+        typeof value !== 'object' ||
+        !Object.hasOwn(value, key)
+      ) {
+        return undefined
+      }
+      value = (value as Record<string, unknown>)[key]
+    }
+    return display(value)
+  }
+
+  let skipLevel: number | null = null
+  for (const token of state.tokens) {
+    if (skipLevel !== null) {
+      if (token.nesting === -1 && token.level === skipLevel) skipLevel = null
+    } else if (token.type === 'html_block') {
+      // a raw html block can open a `v-pre` scope spanning the markdown
+      // after it; that cannot be delimited without parsing the html, so
+      // leave the rest of the page to the runtime
+      if (vPreRE.test(token.content)) return
+    } else if (
+      token.nesting === 1 &&
+      (token.type === 'container_v-pre_open' || hasVPre(token))
+    ) {
+      skipLevel = token.level
+    } else if (token.type === 'inline' && token.children) {
+      processInline(md, state, token, resolve)
+    }
+  }
+}
+
+function processInline(
+  md: MarkdownItAsync,
+  state: StateCore,
+  inline: Token,
+  resolve: Resolve
+): void {
+  const children = inline.children!
+
+  let out: Token[] | undefined
+  let skipLevel: number | null = null
+  let preTag: string | undefined
+  let preDepth = 0
+
+  for (let i = 0; i < children.length; i++) {
+    const child = children[i]
+    let replacement: Token[] | undefined
+    if (skipLevel !== null) {
+      if (child.nesting === -1 && child.level === skipLevel) skipLevel = null
+    } else if (child.type === 'html_inline') {
+      // track raw inline `v-pre` elements the way Vue scopes them
+      const [, closing, tag] = htmlTagRE.exec(child.content) ?? []
+      if (preTag) {
+        if (tag === preTag) preDepth += closing ? -1 : 1
+        if (!preDepth) preTag = undefined
+      } else if (
+        vPreOpenRE.test(child.content) &&
+        !child.content.endsWith('/>')
+      ) {
+        preTag = tag
+        preDepth = 1
+      }
+    } else if (preTag) {
+      // inside a raw v-pre element - leave everything to the runtime
+    } else if (child.nesting === 1 && hasVPre(child)) {
+      skipLevel = child.level
+    } else if (child.type === 'text' && child.content.includes('{{')) {
+      replacement = replaceInterpolations(state, child, resolve)
+    } else if (child.type === 'link_open' || child.type === 'image') {
+      resolveDest(md, child, child.type === 'image' ? 'src' : 'href', resolve)
+    }
+    if (replacement && !out) out = children.slice(0, i)
+    if (out) out.push(...(replacement ?? [child]))
+  }
+  if (out) inline.children = out
+}
+
+// splits a text token around its resolved interpolations; the values become
+// text tokens marked as `frontmatterValue` so extraction (anchors, headers,
+// toc, search) sees them as plain text while the renderer applies value
+// escaping
+function replaceInterpolations(
+  state: StateCore,
+  token: Token,
+  resolve: Resolve
+): Token[] | undefined {
+  const src = token.content
+  let out: Token[] | undefined
+  let lastIndex = 0
+
+  for (const m of src.matchAll(interpolationRE)) {
+    const value = resolve(m[1])
+    if (value === undefined) continue
+    out ??= []
+    if (m.index > lastIndex) {
+      out.push(textToken(state, token, src.slice(lastIndex, m.index)))
+    }
+    const valueToken = textToken(state, token, value)
+    valueToken.meta = { frontmatterValue: true }
+    out.push(valueToken)
+    lastIndex = m.index + m[0].length
+  }
+
+  if (out && lastIndex < src.length) {
+    out.push(textToken(state, token, src.slice(lastIndex)))
+  }
+  return out
+}
+
+// resolves interpolations in a link href or image src, making
+// `[text]({{$frontmatter.link}})` a real link (#2240, #2099); the resolved
+// destination goes through the same normalization and validation a literal
+// one would
+function resolveDest(
+  md: MarkdownItAsync,
+  token: Token,
+  attr: string,
+  resolve: Resolve
+): void {
+  const url = token.attrGet(attr)
+  if (!url) return
+
+  let changed = false
+  const resolved = url.replace(destInterpolationRE, (match, rawExpr) => {
+    let expr = rawExpr as string
+    try {
+      expr = decodeURIComponent(expr)
+    } catch {}
+    const value = resolve(expr)
+    if (value === undefined) return match
+    changed = true
+    return value
+  })
+  if (!changed) return
+
+  const normalized = md.normalizeLink(resolved)
+  if (md.validateLink(normalized)) token.attrSet(attr, normalized)
+}
+
+function textToken(state: StateCore, from: Token, content: string): Token {
+  const token = new state.Token('text', '', 0)
+  token.content = content
+  token.level = from.level
+  return token
+}
+
+// whitespace the Vue template compiler's default `condense` mode would not
+// read back verbatim: any [\t\n\r\f], runs of spaces, or edge spaces that
+// could merge with adjacent whitespace
+const unstableWhitespaceRE = /[\t\n\r\f]|^ | $| {2}/
+
+// mirrors Vue's `toDisplayString`, restricted to values that inline
+// losslessly: non-empty primitive text that survives the template
+// compiler's whitespace condensing. Anything else - including `null`, which
+// renders as an empty string but is also the classic "filled in later by
+// `transformPageData`" placeholder - stays on the runtime.
+function display(value: unknown): string | undefined {
+  if (value == null || typeof value === 'object') return undefined
+  const text = typeof value === 'string' ? value : String(value)
+  return text === '' || unstableWhitespaceRE.test(text) ? undefined : text
+}
+
+// entity-encode the value so the Vue template compiler reads back exactly
+// this text: html syntax must not be parsed as markup, entity look-alikes
+// must survive the compiler's decoding, and `{` must never reach the
+// compiler as a possible interpolation start
+function escapeValue(value: string): string {
+  return value
+    .replace(/&/g, '&amp;')
+    .replace(/</g, '&lt;')
+    .replace(/>/g, '&gt;')
+    .replace(/\{/g, '&#123;')
+    .replace(/\}/g, '&#125;')
+}
+
+function hasVPre(token: Token): boolean {
+  return token.attrGet('v-pre') !== null
+}