fix: hide legacy title chrome for frontmatter titles

src/utils/noteTitle.test.ts

@@ -1,5 +1,11 @@
 import { describe, expect, it } from 'vitest'
-import { deriveDisplayTitleState, extractH1TitleFromContent, filenameStemToTitle } from './noteTitle'
+import {
+  contentDefinesDisplayTitle,
+  deriveDisplayTitleState,
+  extractFrontmatterTitleFromContent,
+  extractH1TitleFromContent,
+  filenameStemToTitle,
+} from './noteTitle'
 
 describe('filenameStemToTitle', () => {
   it('converts kebab-case filenames into title case', () => {
@@ -23,10 +29,32 @@ describe('extractH1TitleFromContent', () => {
   })
 })
 
+describe('extractFrontmatterTitleFromContent', () => {
+  it('extracts the frontmatter title when present', () => {
+    const content = '---\ntitle: Legacy Title\nstatus: Active\n---\n## Body'
+    expect(extractFrontmatterTitleFromContent(content)).toBe('Legacy Title')
+  })
+
+  it('returns null when the frontmatter title is missing', () => {
+    expect(extractFrontmatterTitleFromContent('---\nstatus: Active\n---\n## Body')).toBeNull()
+  })
+})
+
+describe('contentDefinesDisplayTitle', () => {
+  it('returns true when the document title comes from frontmatter', () => {
+    const content = '---\ntitle: Spring 2026\n---\n## Goals'
+    expect(contentDefinesDisplayTitle(content)).toBe(true)
+  })
+
+  it('returns false when title still comes from the filename', () => {
+    expect(contentDefinesDisplayTitle('Body only')).toBe(false)
+  })
+})
+
 describe('deriveDisplayTitleState', () => {
   it('prefers H1 over frontmatter title and filename', () => {
     const content = '---\ntitle: Legacy Title\n---\n# Updated Title\n\nBody'
-    expect(deriveDisplayTitleState(content, 'legacy-title.md', 'Legacy Title')).toEqual({
+    expect(deriveDisplayTitleState({ content, filename: 'legacy-title.md', frontmatterTitle: 'Legacy Title' })).toEqual({
       title: 'Updated Title',
       hasH1: true,
     })
@@ -34,14 +62,22 @@ describe('deriveDisplayTitleState', () => {
 
   it('falls back to frontmatter title when no H1 is present', () => {
     const content = '---\ntitle: Legacy Title\n---\nBody'
-    expect(deriveDisplayTitleState(content, 'legacy-title.md', 'Legacy Title')).toEqual({
+    expect(deriveDisplayTitleState({ content, filename: 'legacy-title.md', frontmatterTitle: 'Legacy Title' })).toEqual({
       title: 'Legacy Title',
       hasH1: false,
     })
   })
 
+  it('reads the frontmatter title from content when no explicit title is passed', () => {
+    const content = '---\ntitle: Spring 2026\n---\n## Goals'
+    expect(deriveDisplayTitleState({ content, filename: 'spring-2026.md' })).toEqual({
+      title: 'Spring 2026',
+      hasH1: false,
+    })
+  })
+
   it('falls back to filename title when there is no H1 or frontmatter title', () => {
-    expect(deriveDisplayTitleState('Body only', 'renamed-note.md')).toEqual({
+    expect(deriveDisplayTitleState({ content: 'Body only', filename: 'renamed-note.md' })).toEqual({
       title: 'Renamed Note',
       hasH1: false,
     })

src/utils/noteTitle.ts

@@ -1,5 +1,22 @@
+import { parseFrontmatter } from './frontmatter'
 import { splitFrontmatter } from './wikilinks'
 
+interface ResolvedContentTitle {
+  source: 'h1' | 'frontmatter'
+  title: string
+}
+
+interface DisplayTitleInput {
+  content: string
+  filename: string
+  frontmatterTitle?: string | null
+}
+
+interface DisplayTitleState {
+  title: string
+  hasH1: boolean
+}
+
 function replaceWikilinkAliases(text: string): string {
   return text.replace(/\[\[[^|\]]+\|([^\]]+)\]\]/g, '$1')
 }
@@ -49,20 +66,46 @@ export function extractH1TitleFromContent(content: string): string | null {
   return null
 }
 
-export function deriveDisplayTitleState(
-  content: string,
-  filename: string,
-  frontmatterTitle?: string | null,
-): { title: string, hasH1: boolean } {
+export function extractFrontmatterTitleFromContent(content: string): string | null {
+  const title = parseFrontmatter(content).title
+  if (typeof title !== 'string') return null
+  const trimmed = title.trim()
+  return trimmed || null
+}
+
+function resolveContentTitle(content: string, frontmatterTitle?: string | null): ResolvedContentTitle | null {
   const h1Title = extractH1TitleFromContent(content)
   if (h1Title) {
-    return { title: h1Title, hasH1: true }
+    return { title: h1Title, source: 'h1' }
   }
 
-  const trimmedFrontmatterTitle = frontmatterTitle?.trim()
-  if (trimmedFrontmatterTitle) {
-    return { title: trimmedFrontmatterTitle, hasH1: false }
+  const resolvedFrontmatterTitle = frontmatterTitle?.trim() || extractFrontmatterTitleFromContent(content)
+  if (resolvedFrontmatterTitle) {
+    return { title: resolvedFrontmatterTitle, source: 'frontmatter' }
   }
 
-  return { title: filenameStemToTitle(filename), hasH1: false }
+  return null
+}
+
+export function contentDefinesDisplayTitle(content: string): boolean {
+  return resolveContentTitle(content) !== null
+}
+
+export function deriveDisplayTitleState({
+  content,
+  filename,
+  frontmatterTitle,
+}: DisplayTitleInput): DisplayTitleState {
+  const resolvedTitle = resolveContentTitle(content, frontmatterTitle)
+  if (resolvedTitle) {
+    return {
+      title: resolvedTitle.title,
+      hasH1: resolvedTitle.source === 'h1',
+    }
+  }
+
+  return {
+    title: filenameStemToTitle(filename),
+    hasH1: false,
+  }
 }