fix: make new note editor immediately interactive

Extract heading-stripping logic into `extractEditorBody` — fixes a bug
where the regex failed to strip the title heading from newly created
notes (because `splitFrontmatter` left a leading newline that the
regex didn't account for).

Add a fast path in `doSwap` for empty body content: when the body is
empty (common case for new notes), skip the potentially-async
`tryParseMarkdownToBlocks` pipeline entirely and apply a single empty
paragraph block synchronously. This eliminates the multi-second delay
caused by BlockNote's async markdown parser initialization.

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

src/hooks/useEditorTabSwap.test.ts

@@ -0,0 +1,54 @@
+import { describe, it, expect } from 'vitest'
+import { extractEditorBody } from './useEditorTabSwap'
+
+describe('extractEditorBody', () => {
+  it('strips frontmatter and title heading from new note content (double newline)', () => {
+    const content = '---\ntitle: Untitled note\ntype: Note\nstatus: Active\n---\n\n# Untitled note\n\n'
+    expect(extractEditorBody(content)).toBe('')
+  })
+
+  it('strips frontmatter and title heading from content with single newline', () => {
+    const content = '---\ntitle: Test\n---\n# Test\n\nBody text here.'
+    expect(extractEditorBody(content)).toBe('Body text here.')
+  })
+
+  it('preserves body content after the heading', () => {
+    const content = '---\ntitle: My Note\ntype: Note\n---\n\n# My Note\n\nFirst paragraph.\n\nSecond paragraph.'
+    expect(extractEditorBody(content)).toBe('First paragraph.\n\nSecond paragraph.')
+  })
+
+  it('handles content without frontmatter', () => {
+    const content = '# Just a Heading\n\nSome body text.'
+    expect(extractEditorBody(content)).toBe('Some body text.')
+  })
+
+  it('handles content without frontmatter or heading', () => {
+    const content = 'Just plain text.'
+    expect(extractEditorBody(content)).toBe('Just plain text.')
+  })
+
+  it('handles completely empty content', () => {
+    expect(extractEditorBody('')).toBe('')
+  })
+
+  it('handles frontmatter-only content', () => {
+    const content = '---\ntitle: Empty\n---\n'
+    expect(extractEditorBody(content)).toBe('')
+  })
+
+  it('preserves wikilinks in body', () => {
+    const content = '---\ntitle: Test\n---\n\n# Test\n\nSee [[Other Note]] for details.'
+    expect(extractEditorBody(content)).toBe('See [[Other Note]] for details.')
+  })
+
+  it('does not strip heading that is not at the start of body', () => {
+    const content = '---\ntitle: Test\n---\n\nSome intro text.\n\n# A Heading\n\nMore text.'
+    expect(extractEditorBody(content)).toBe('Some intro text.\n\n# A Heading\n\nMore text.')
+  })
+
+  it('returns empty for buildNoteContent output', () => {
+    // Exactly what buildNoteContent('My Project', 'Project', 'Active') produces
+    const content = '---\ntitle: My Project\ntype: Project\nstatus: Active\n---\n\n# My Project\n\n'
+    expect(extractEditorBody(content)).toBe('')
+  })
+})

src/hooks/useEditorTabSwap.ts

@@ -15,6 +15,13 @@ interface UseEditorTabSwapOptions {
   onContentChange?: (path: string, content: string) => void
 }
 
+/** Strip the YAML frontmatter and the title heading (# ...) from raw file
+ *  content, returning only the body that should appear in the editor. */
+export function extractEditorBody(rawFileContent: string): string {
+  const [, rawBody] = splitFrontmatter(rawFileContent)
+  return rawBody.trimStart().replace(/^# [^\n]*\n?/, '').trimStart()
+}
+
 /**
  * Manages the tab content-swap machinery for the BlockNote editor.
  *
@@ -151,10 +158,19 @@ export function useEditorTabSwap({ tabs, activeTabPath, editor, onContentChange
         return
       }
 
-      const [, rawBody] = splitFrontmatter(tab.content)
-      const body = rawBody.replace(/^# [^\n]*\n?/, '').trimStart()
+      const body = extractEditorBody(tab.content)
       const preprocessed = preProcessWikilinks(body)
 
+      // Fast path: empty body (e.g. newly created notes). Skip the
+      // potentially-async markdown parser and set a single empty paragraph
+      // so the editor is immediately interactive.
+      if (!preprocessed.trim()) {
+        const emptyDoc = [{ type: 'paragraph', content: [] }]
+        cache.set(targetPath, emptyDoc)
+        applyBlocks(emptyDoc)
+        return
+      }
+
       try {
         const result = editor.tryParseMarkdownToBlocks(preprocessed)
         // eslint-disable-next-line @typescript-eslint/no-explicit-any -- BlockNote block arrays