fix: post-process BlockNote serializer to remove extra blank lines

blocksToMarkdownLossy() inserts blank lines between every block, making
tight lists loose and polluting git history. Add compactMarkdown() that
collapses inter-list-item blanks and excessive blank line runs while
preserving code blocks and intentional paragraph spacing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/hooks/useEditorTabSwap.ts

@@ -3,6 +3,7 @@ import { useCallback, useEffect, useRef } from 'react'
 import type { useCreateBlockNote } from '@blocknote/react'
 import type { VaultEntry } from '../types'
 import { splitFrontmatter, preProcessWikilinks, injectWikilinks, restoreWikilinksInBlocks } from '../utils/wikilinks'
+import { compactMarkdown } from '../utils/compact-markdown'
 
 interface Tab {
   entry: VaultEntry
@@ -111,7 +112,7 @@ export function useEditorTabSwap({ tabs, activeTabPath, editor, onContentChange,
     // Convert blocks → markdown, restoring wikilinks first
     const blocks = editor.document
     const restored = restoreWikilinksInBlocks(blocks)
-    const bodyMarkdown = editor.blocksToMarkdownLossy(restored as typeof blocks)
+    const bodyMarkdown = compactMarkdown(editor.blocksToMarkdownLossy(restored as typeof blocks))
 
     // Reconstruct full file: frontmatter + body (which now includes H1 if present)
     const [frontmatter] = splitFrontmatter(tab.content)

src/utils/compact-markdown.test.ts

@@ -0,0 +1,102 @@
+import { describe, it, expect } from 'vitest'
+import { compactMarkdown } from './compact-markdown'
+
+describe('compactMarkdown', () => {
+  it('collapses blank lines between bullet list items (tight list)', () => {
+    const input = '* Item one\n\n* Item two\n\n* Item three\n'
+    expect(compactMarkdown(input)).toBe('* Item one\n* Item two\n* Item three\n')
+  })
+
+  it('collapses blank lines between dash list items', () => {
+    const input = '- Item one\n\n- Item two\n\n- Item three\n'
+    expect(compactMarkdown(input)).toBe('- Item one\n- Item two\n- Item three\n')
+  })
+
+  it('collapses blank lines between numbered list items', () => {
+    const input = '1. First\n\n2. Second\n\n3. Third\n'
+    expect(compactMarkdown(input)).toBe('1. First\n2. Second\n3. Third\n')
+  })
+
+  it('removes extra blank line after heading', () => {
+    const input = '## Personal\n\n* Back on track\n\n* Good health\n'
+    expect(compactMarkdown(input)).toBe('## Personal\n\n* Back on track\n* Good health\n')
+  })
+
+  it('preserves single blank line between heading and content', () => {
+    const input = '## Title\n\nSome paragraph text.\n'
+    expect(compactMarkdown(input)).toBe('## Title\n\nSome paragraph text.\n')
+  })
+
+  it('collapses multiple blank lines after heading to one', () => {
+    const input = '## Title\n\n\n\nSome paragraph text.\n'
+    expect(compactMarkdown(input)).toBe('## Title\n\nSome paragraph text.\n')
+  })
+
+  it('preserves blank lines between paragraphs', () => {
+    const input = 'First paragraph.\n\nSecond paragraph.\n'
+    expect(compactMarkdown(input)).toBe('First paragraph.\n\nSecond paragraph.\n')
+  })
+
+  it('preserves blank lines inside fenced code blocks', () => {
+    const input = '```\nline one\n\nline two\n\nline three\n```\n'
+    expect(compactMarkdown(input)).toBe('```\nline one\n\nline two\n\nline three\n```\n')
+  })
+
+  it('preserves blank lines inside fenced code blocks with language', () => {
+    const input = '```js\nconst a = 1\n\nconst b = 2\n```\n'
+    expect(compactMarkdown(input)).toBe('```js\nconst a = 1\n\nconst b = 2\n```\n')
+  })
+
+  it('does not add trailing blank lines', () => {
+    const input = '## Title\n\nText.\n\n\n'
+    expect(compactMarkdown(input)).toBe('## Title\n\nText.\n')
+  })
+
+  it('handles the exact bug scenario from the issue', () => {
+    const input = '## Personal\n\n* Back on track with Flavia\n\n* Good health vitals in place\n\n'
+    expect(compactMarkdown(input)).toBe('## Personal\n\n* Back on track with Flavia\n* Good health vitals in place\n')
+  })
+
+  it('handles heading followed immediately by list (no blank line)', () => {
+    const input = '## Title\n* Item one\n\n* Item two\n'
+    expect(compactMarkdown(input)).toBe('## Title\n* Item one\n* Item two\n')
+  })
+
+  it('handles mixed content: heading, paragraph, list', () => {
+    const input = '# Title\n\nSome intro.\n\n* Item one\n\n* Item two\n\nConclusion.\n'
+    expect(compactMarkdown(input)).toBe('# Title\n\nSome intro.\n\n* Item one\n* Item two\n\nConclusion.\n')
+  })
+
+  it('preserves empty input', () => {
+    expect(compactMarkdown('')).toBe('')
+  })
+
+  it('preserves single line', () => {
+    expect(compactMarkdown('Hello\n')).toBe('Hello\n')
+  })
+
+  it('collapses 3+ consecutive blank lines to one blank line', () => {
+    const input = 'Paragraph one.\n\n\n\nParagraph two.\n'
+    expect(compactMarkdown(input)).toBe('Paragraph one.\n\nParagraph two.\n')
+  })
+
+  it('handles list after code block', () => {
+    const input = '```\ncode\n```\n\n* Item one\n\n* Item two\n'
+    expect(compactMarkdown(input)).toBe('```\ncode\n```\n\n* Item one\n* Item two\n')
+  })
+
+  it('handles nested list items', () => {
+    const input = '* Parent\n\n  * Child one\n\n  * Child two\n'
+    expect(compactMarkdown(input)).toBe('* Parent\n  * Child one\n  * Child two\n')
+  })
+
+  it('handles checklist items', () => {
+    const input = '* [ ] Todo one\n\n* [ ] Todo two\n\n* [x] Done\n'
+    expect(compactMarkdown(input)).toBe('* [ ] Todo one\n* [ ] Todo two\n* [x] Done\n')
+  })
+
+  it('handles blockquotes normally', () => {
+    const input = '> Quote line one\n\n> Quote line two\n'
+    expect(compactMarkdown(input)).toBe('> Quote line one\n\n> Quote line two\n')
+  })
+})

src/utils/compact-markdown.ts

@@ -0,0 +1,82 @@
+/**
+ * Post-process BlockNote's blocksToMarkdownLossy output to produce
+ * standard-convention Markdown:
+ * - Tight lists (no blank lines between consecutive list items)
+ * - No runs of 3+ blank lines (collapsed to one blank line)
+ * - No trailing blank lines
+ * - Code block content is never modified
+ */
+export function compactMarkdown(md: string): string {
+  if (!md) return md
+
+  const lines = md.split('\n')
+  const result: string[] = []
+  let inCodeBlock = false
+
+  for (let i = 0; i < lines.length; i++) {
+    const line = lines[i]
+
+    // Track fenced code blocks — never modify content inside them
+    if (line.trimStart().startsWith('```')) {
+      inCodeBlock = !inCodeBlock
+      result.push(line)
+      continue
+    }
+
+    if (inCodeBlock) {
+      result.push(line)
+      continue
+    }
+
+    // Skip blank lines that sit between two list items (tight list rule)
+    if (line.trim() === '') {
+      if (isBlankBetweenListItems(lines, i)) continue
+      // Collapse runs of 3+ blank lines to a single blank line
+      if (isExcessiveBlankLine(lines, i)) continue
+      result.push(line)
+      continue
+    }
+
+    result.push(line)
+  }
+
+  // Trim trailing blank lines, keep exactly one trailing newline
+  while (result.length > 0 && result[result.length - 1].trim() === '') {
+    result.pop()
+  }
+  if (result.length > 0) result.push('')
+
+  return result.join('\n')
+}
+
+const LIST_RE = /^(\s*)([-*+]|\d+\.)\s/
+
+/** True if this blank line sits between two list items (including nested) */
+function isBlankBetweenListItems(lines: string[], idx: number): boolean {
+  const prev = findPrevNonBlank(lines, idx)
+  const next = findNextNonBlank(lines, idx)
+  if (prev === null || next === null) return false
+  return LIST_RE.test(lines[prev]) && LIST_RE.test(lines[next])
+}
+
+/** True if this blank line is part of a run of 2+ consecutive blank lines
+ *  (i.e. would create 3+ newlines in a row — collapse to just one blank line) */
+function isExcessiveBlankLine(lines: string[], idx: number): boolean {
+  // Keep the first blank line in a run, skip subsequent ones
+  if (idx > 0 && lines[idx - 1].trim() === '') return true
+  return false
+}
+
+function findPrevNonBlank(lines: string[], idx: number): number | null {
+  for (let i = idx - 1; i >= 0; i--) {
+    if (lines[i].trim() !== '') return i
+  }
+  return null
+}
+
+function findNextNonBlank(lines: string[], idx: number): number | null {
+  for (let i = idx + 1; i < lines.length; i++) {
+    if (lines[i].trim() !== '') return i
+  }
+  return null
+}