fix: make code block height content-aware

tests/e2e/presenter.spec.ts

@@ -261,14 +261,14 @@ test('presenter advances animations, switches notes, shows timing, and syncs the
   await presenter.getByTitle('Go to next slide').click()
   await expect(page.getByRole('heading', { name: '内容优先' })).toBeVisible()
   await expect(presenter.getByText('依次介绍四个核心能力')).toBeVisible()
-  await expect(presenter.getByText('2 / 8', { exact: true })).toBeVisible()
+  await expect(presenter.getByText('2 / 9', { exact: true })).toBeVisible()
 
   await presenter.getByTitle('Go to next slide').click()
   await expect(presenter.getByText('1/4', { exact: true })).toBeVisible()
   await expect(page).toHaveURL(/#\/2\?clicks=1$/)
 })
 
-test('table and code controls adjust font size while code fills the available height', async ({ page }) => {
+test('table and code controls adjust font size while code uses smart height', async ({ page }) => {
   await page.goto('/getting-started/#/7')
   const table = page.locator('.slidev-layout table').first()
   const tablePreset = table.locator('..').locator('..')
@@ -311,15 +311,8 @@ test('table and code controls adjust font size while code fills the available he
   await expect.poll(() => code.evaluate(element => Number.parseFloat(getComputedStyle(element).fontSize))).toBe(initialCodeSize)
 
   await expect.poll(() => code.evaluate((element) => {
-    const region = element.closest('.easy-two-cols-grid > div')!
-    const layout = element.closest('.slidev-layout') as HTMLElement
-    const scale = layout.getBoundingClientRect().height / layout.clientHeight
-    const contentBottom = Math.min(
-      region.getBoundingClientRect().bottom - Number.parseFloat(getComputedStyle(region).paddingBottom) * scale,
-      layout.getBoundingClientRect().bottom - Number.parseFloat(getComputedStyle(layout).paddingBottom) * scale,
-    )
-    return Math.abs(contentBottom - element.getBoundingClientRect().bottom) / scale
-  })).toBeLessThanOrEqual(3)
+    return element.scrollHeight - element.clientHeight
+  })).toBeGreaterThan(0)
   const overflow = await code.evaluate(element => ({
     horizontal: getComputedStyle(element).overflowX,
     lineHeight: Number.parseFloat(getComputedStyle(element).lineHeight),
@@ -365,16 +358,46 @@ test('table and code controls adjust font size while code fills the available he
   await layout.evaluate((element) => {
     element.classList.remove('easy-code-height-sm', 'easy-code-height-md', 'easy-code-height-lg')
   })
+  await expect.poll(() => code.evaluate(element => element.scrollHeight - element.clientHeight)).toBeGreaterThan(0)
+})
+
+test('auto-height code keeps its natural height and reserves room for following content', async ({ page }) => {
+  await page.goto('/getting-started/#/8')
+  const layout = page.locator('.slidev-page-8 .slidev-layout')
+  const code = layout.locator('pre').first()
+  const following = layout.getByRole('heading', { name: '代码之后的正文仍保留在内容区内' })
+
+  await expect(following).toBeVisible()
   await expect.poll(() => code.evaluate((element) => {
-    const region = element.closest('.easy-two-cols-grid > div')!
-    const layout = element.closest('.slidev-layout') as HTMLElement
-    const scale = layout.getBoundingClientRect().height / layout.clientHeight
-    const contentBottom = Math.min(
-      region.getBoundingClientRect().bottom - Number.parseFloat(getComputedStyle(region).paddingBottom) * scale,
-      layout.getBoundingClientRect().bottom - Number.parseFloat(getComputedStyle(layout).paddingBottom) * scale,
-    )
-    return Math.abs(contentBottom - element.getBoundingClientRect().bottom) / scale
-  })).toBeLessThanOrEqual(3)
+    const layoutElement = element.closest('.slidev-layout') as HTMLElement
+    const scale = layoutElement.getBoundingClientRect().height / layoutElement.clientHeight
+    return Math.abs(element.getBoundingClientRect().height / scale - element.scrollHeight)
+  })).toBeLessThanOrEqual(1)
+  const bounds = await layout.evaluate((element) => {
+    const codeElement = element.querySelector('pre')!
+    const followingElement = Array.from(element.querySelectorAll('h3')).find(item => item.textContent?.includes('代码之后的正文'))!
+    return {
+      codeBottom: codeElement.getBoundingClientRect().bottom,
+      followingBottom: followingElement.getBoundingClientRect().bottom,
+      followingTop: followingElement.getBoundingClientRect().top,
+      layoutBottom: element.getBoundingClientRect().bottom - Number.parseFloat(getComputedStyle(element).paddingBottom),
+    }
+  })
+  expect(bounds.codeBottom).toBeLessThan(bounds.followingTop)
+  expect(bounds.followingBottom).toBeLessThanOrEqual(bounds.layoutBottom + 1)
+
+  await code.evaluate((element) => {
+    element.textContent = Array.from({ length: 40 }, (_, index) => `line ${index + 1}: a deliberately long code sample`).join('\n')
+  })
+  await expect.poll(() => code.evaluate(element => element.scrollHeight - element.clientHeight)).toBeGreaterThan(100)
+  const longContentBounds = await layout.evaluate((element) => {
+    const followingElement = Array.from(element.querySelectorAll('h3')).find(item => item.textContent?.includes('代码之后的正文'))!
+    return {
+      followingBottom: followingElement.getBoundingClientRect().bottom,
+      layoutBottom: element.getBoundingClientRect().bottom - Number.parseFloat(getComputedStyle(element).paddingBottom),
+    }
+  })
+  expect(longContentBounds.followingBottom).toBeLessThanOrEqual(longContentBounds.layoutBottom + 1)
 })
 
 test('image fullscreen preserves layout and table scaling stays out of non-interactive routes', async ({ page }) => {
@@ -601,7 +624,7 @@ test('stacked image layouts constrain wide images by available height', async ({
 
 test('sample slides stay inside the 4:3 canvas', async ({ page }) => {
   await page.goto('/getting-started/#/1')
-  for (let slide = 1; slide <= 8; slide += 1) {
+  for (let slide = 1; slide <= 9; slide += 1) {
     const layout = page.locator('.slidev-layout').first()
     await expect(layout).toBeVisible()
     const box = await layout.boundingBox()