fix: 修复笔记 YAML 标签保存与索引重建一致性

backend/app/knowledge/parser.py

@@ -20,7 +20,6 @@ from app.errors import ApiError
 from app.textutils import count_tokens
 
 _HEADING_RE = re.compile(r"^(#{1,6})[ \t]+(.*?)\s*$")
-_FRONTMATTER_KEY_RE = re.compile(r"^([A-Za-z0-9_-]+)\s*:\s*(.*)$")
 _FENCE_RE = re.compile(r"^[ \t]{0,3}(`{3,}|~{3,})(?:[^`]*)$")
 
 
@@ -261,16 +260,29 @@ def _embedding_policy(markdown: str) -> bool:
     return value.value.lower() in {"true", "yes", "on"}
 
 
-def _extract_frontmatter(markdown: str) -> dict[str, str]:
+def _extract_frontmatter(markdown: str) -> dict[str, str | list[str]]:
-    """极简 frontmatter 解析，只提取 key: value 行。"""
+    """Read YAML scalars and tag sequences without constructing arbitrary objects."""
     header = _frontmatter(markdown)
     if header is None:
         return {}
-    meta: dict[str, str] = {}
+    try:
-    for line in header[0].splitlines():
+        node = yaml.compose(header[0], Loader=yaml.SafeLoader)
-        m = _FRONTMATTER_KEY_RE.match(line)
+    except yaml.YAMLError as exc:
-        if m:
+        raise ApiError(422, "INVALID_EMBEDDING_POLICY", "Frontmatter YAML 无效，无法确认本地索引策略。") from exc
-            meta[m.group(1).lower()] = m.group(2).strip()
+    meta: dict[str, str | list[str]] = {}
+    if not isinstance(node, yaml.MappingNode):
+        return meta  # The policy validation below handles unsupported documents.
+    for key, value in node.value:
+        if not isinstance(key, yaml.ScalarNode):
+            continue
+        name = key.value.lower()
+        if name not in {"title", "tags"}:
+            continue
+        if isinstance(value, yaml.ScalarNode):
+            # Keep lexical values: YAML 1.1 would otherwise turn tags like on/yes into booleans.
+            meta[name] = "" if value.tag == "tag:yaml.org,2002:null" else value.value
+        elif name == "tags" and isinstance(value, yaml.SequenceNode):
+            meta[name] = [item.value for item in value.value if isinstance(item, yaml.ScalarNode)]
     return meta
 
 
@@ -282,10 +294,10 @@ def _first_heading(markdown: str) -> str | None:
     return None
 
 
-def _parse_tags(raw: str | None) -> list[str]:
+def _parse_tags(raw: str | list[str] | None) -> list[str]:
+    if isinstance(raw, list):
+        return raw
     if not raw:
         return []
     raw = raw.strip()
-    if raw.startswith("[") and raw.endswith("]"):
+    return [t.strip() for t in raw.split(",") if t.strip()]
-        raw = raw[1:-1]
-    return [t.strip().strip("'\"") for t in raw.split(",") if t.strip()]

backend/tests/test_note_metadata.py

@@ -0,0 +1,46 @@
+import asyncio
+from datetime import datetime, timezone
+
+import pytest
+
+from app.contracts import IndexRebuildRequest
+from app.knowledge.parser import parse_note
+from app.services import index_service, note_service
+
+
+@pytest.mark.parametrize(('header', 'expected'), [
+    ('tags:\n- python\n- rust', ['python', 'rust']),
+    ('tags:\n  - python\n  - rust', ['python', 'rust']),
+    ('"tags": ["a,b", "quote\\\"tag", "path\\\\tag"] # comment', ['a,b', 'quote"tag', 'path\\tag']),
+    ('tags: [on, yes, "true", "001"]', ['on', 'yes', 'true', '001']),
+    ('tags: python, rust', ['python', 'rust']),
+    ('tags: []', []),
+    ('tags: null', []),
+])
+def test_yaml_tags_are_parsed_as_complete_values(header, expected):
+    now = datetime.now(timezone.utc)
+    note = parse_note(
+        markdown=f'---\ntitle: "Demo: YAML"\n{header}\n---\n# Body',
+        file_path='demo.md', folder='', created_at=now, updated_at=now,
+    )
+    assert note.tags == expected
+    assert note.title == 'Demo: YAML'
+
+
+def test_saved_metadata_survives_full_index_rebuild():
+    async def scenario():
+        note = await note_service.create_note(title='Demo', markdown='# Body', folder=None, tags=['old'])
+        for tags, yaml_tags in [
+            (['python', 'a,b', 'on'], '\n  - python\n  - a,b\n  - on'),
+            ([], ' []'),
+        ]:
+            markdown = f'---\ntitle: "Demo: updated"\ntags:{yaml_tags}\n---\n# Body\n'
+            saved = await note_service.update_note(note.note_id, markdown=markdown, tags=tags)
+            assert saved.tags == tags
+            job = await index_service.rebuild(IndexRebuildRequest())
+            assert job.status == 'completed'
+            restored = await note_service.get_note(note.note_id)
+            assert restored.tags == tags
+            assert restored.title == 'Demo: updated'
+            assert restored.markdown == markdown
+    asyncio.run(scenario())

frontend/package.json

@@ -41,7 +41,8 @@
     "pinia": "^4.0.0",
     "shiki": "^4.4.3",
     "vue": "^3.5.0",
-    "vue-router": "^5.0.0"
+    "vue-router": "^5.0.0",
+    "yaml": "^2.9.0"
   },
   "devDependencies": {
     "@types/node": "^22.0.0",

frontend/pnpm-lock.yaml

@@ -100,14 +100,17 @@ importers:
         version: 3.5.42(typescript@5.9.3)
       vue-router:
         specifier: ^5.0.0
-        version: 5.3.0(@vue/compiler-sfc@3.5.42)(esbuild@0.25.12)(pinia@4.0.3(@vue/devtools-api@8.2.1)(typescript@5.9.3)(vue@3.5.42(typescript@5.9.3)))(rollup@4.63.1)(vite@6.4.3(@types/node@22.20.1))(vue@3.5.42(typescript@5.9.3))
+        version: 5.3.0(@vue/compiler-sfc@3.5.42)(esbuild@0.25.12)(pinia@4.0.3(@vue/devtools-api@8.2.1)(typescript@5.9.3)(vue@3.5.42(typescript@5.9.3)))(rollup@4.63.1)(vite@6.4.3(@types/node@22.20.1)(yaml@2.9.0))(vue@3.5.42(typescript@5.9.3))
+      yaml:
+        specifier: ^2.9.0
+        version: 2.9.0
     devDependencies:
       '@types/node':
         specifier: ^22.0.0
         version: 22.20.1
       '@vitejs/plugin-vue':
         specifier: ^5.0.0
-        version: 5.2.4(vite@6.4.3(@types/node@22.20.1))(vue@3.5.42(typescript@5.9.3))
+        version: 5.2.4(vite@6.4.3(@types/node@22.20.1)(yaml@2.9.0))(vue@3.5.42(typescript@5.9.3))
       '@vue/test-utils':
         specifier: ^2.5.0
         version: 2.5.0(@vue/compiler-dom@3.5.42)(@vue/server-renderer@3.5.42)(vue@3.5.42(typescript@5.9.3))
@@ -119,10 +122,10 @@ importers:
         version: 5.9.3
       vite:
         specifier: ^6.0.0
-        version: 6.4.3(@types/node@22.20.1)
+        version: 6.4.3(@types/node@22.20.1)(yaml@2.9.0)
       vitest:
         specifier: ^4.1.11
-        version: 4.1.11(@types/node@22.20.1)(happy-dom@20.11.15)(vite@6.4.3(@types/node@22.20.1))
+        version: 4.1.11(@types/node@22.20.1)(happy-dom@20.11.15)(vite@6.4.3(@types/node@22.20.1)(yaml@2.9.0))
       vue-tsc:
         specifier: ^2.0.0
         version: 2.2.12(typescript@5.9.3)
@@ -2150,6 +2153,11 @@ packages:
       utf-8-validate:
         optional: true
 
+  yaml@2.9.0:
+    resolution: {integrity: sha512-2AvhNX3mb8zd6Zy7INTtSpl1F15HW6Wnqj0srWlkKLcpYl/gMIMJiyuGq2KeI2YFxUPjdlB+3Lc10seMLtL4cA==}
+    engines: {node: '>= 14.6'}
+    hasBin: true
+
   zwitch@2.0.4:
     resolution: {integrity: sha512-bXE4cR/kVZhKZX/RjPEflHaKVhUVl85noU3v6b8apfQEc1x4A+zBxjZ4lN8LqGd6WZ3dl98pY4o717VFmoPp+A==}
 
@@ -3259,9 +3267,9 @@ snapshots:
       d3-selection: 3.0.0
       d3-transition: 3.0.1(d3-selection@3.0.0)
 
-  '@vitejs/plugin-vue@5.2.4(vite@6.4.3(@types/node@22.20.1))(vue@3.5.42(typescript@5.9.3))':
+  '@vitejs/plugin-vue@5.2.4(vite@6.4.3(@types/node@22.20.1)(yaml@2.9.0))(vue@3.5.42(typescript@5.9.3))':
     dependencies:
-      vite: 6.4.3(@types/node@22.20.1)
+      vite: 6.4.3(@types/node@22.20.1)(yaml@2.9.0)
       vue: 3.5.42(typescript@5.9.3)
 
   '@vitest/expect@4.1.11':
@@ -3273,13 +3281,13 @@ snapshots:
       chai: 6.2.2
       tinyrainbow: 3.1.1
 
-  '@vitest/mocker@4.1.11(vite@6.4.3(@types/node@22.20.1))':
+  '@vitest/mocker@4.1.11(vite@6.4.3(@types/node@22.20.1)(yaml@2.9.0))':
     dependencies:
       '@vitest/spy': 4.1.11
       estree-walker: 3.0.3
       magic-string: 0.30.21
     optionalDependencies:
-      vite: 6.4.3(@types/node@22.20.1)
+      vite: 6.4.3(@types/node@22.20.1)(yaml@2.9.0)
 
   '@vitest/pretty-format@4.1.11':
     dependencies:
@@ -4680,7 +4688,7 @@ snapshots:
       pathe: 2.0.3
       picomatch: 4.0.7
 
-  unplugin@3.3.0(esbuild@0.25.12)(rollup@4.63.1)(vite@6.4.3(@types/node@22.20.1)):
+  unplugin@3.3.0(esbuild@0.25.12)(rollup@4.63.1)(vite@6.4.3(@types/node@22.20.1)(yaml@2.9.0)):
     dependencies:
       '@jridgewell/remapping': 2.3.5
       picomatch: 4.0.7
@@ -4688,7 +4696,7 @@ snapshots:
     optionalDependencies:
       esbuild: 0.25.12
       rollup: 4.63.1
-      vite: 6.4.3(@types/node@22.20.1)
+      vite: 6.4.3(@types/node@22.20.1)(yaml@2.9.0)
 
   uuid@14.0.2: {}
 
@@ -4702,7 +4710,7 @@ snapshots:
       '@types/unist': 3.0.3
       vfile-message: 4.0.3
 
-  vite@6.4.3(@types/node@22.20.1):
+  vite@6.4.3(@types/node@22.20.1)(yaml@2.9.0):
     dependencies:
       esbuild: 0.25.12
       fdir: 6.5.0(picomatch@4.0.7)
@@ -4713,11 +4721,12 @@ snapshots:
     optionalDependencies:
       '@types/node': 22.20.1
       fsevents: 2.3.3
+      yaml: 2.9.0
 
-  vitest@4.1.11(@types/node@22.20.1)(happy-dom@20.11.15)(vite@6.4.3(@types/node@22.20.1)):
+  vitest@4.1.11(@types/node@22.20.1)(happy-dom@20.11.15)(vite@6.4.3(@types/node@22.20.1)(yaml@2.9.0)):
     dependencies:
       '@vitest/expect': 4.1.11
-      '@vitest/mocker': 4.1.11(vite@6.4.3(@types/node@22.20.1))
+      '@vitest/mocker': 4.1.11(vite@6.4.3(@types/node@22.20.1)(yaml@2.9.0))
       '@vitest/pretty-format': 4.1.11
       '@vitest/runner': 4.1.11
       '@vitest/snapshot': 4.1.11
@@ -4734,7 +4743,7 @@ snapshots:
       tinyexec: 1.3.0
       tinyglobby: 0.2.17
       tinyrainbow: 3.1.1
-      vite: 6.4.3(@types/node@22.20.1)
+      vite: 6.4.3(@types/node@22.20.1)(yaml@2.9.0)
       why-is-node-running: 2.3.0
     optionalDependencies:
       '@types/node': 22.20.1
@@ -4746,7 +4755,7 @@ snapshots:
 
   vue-component-type-helpers@3.3.11: {}
 
-  vue-router@5.3.0(@vue/compiler-sfc@3.5.42)(esbuild@0.25.12)(pinia@4.0.3(@vue/devtools-api@8.2.1)(typescript@5.9.3)(vue@3.5.42(typescript@5.9.3)))(rollup@4.63.1)(vite@6.4.3(@types/node@22.20.1))(vue@3.5.42(typescript@5.9.3)):
+  vue-router@5.3.0(@vue/compiler-sfc@3.5.42)(esbuild@0.25.12)(pinia@4.0.3(@vue/devtools-api@8.2.1)(typescript@5.9.3)(vue@3.5.42(typescript@5.9.3)))(rollup@4.63.1)(vite@6.4.3(@types/node@22.20.1)(yaml@2.9.0))(vue@3.5.42(typescript@5.9.3)):
     dependencies:
       '@vue-macros/common': 3.1.4(vue@3.5.42(typescript@5.9.3))
       '@vue/devtools-api': 8.2.1
@@ -4762,13 +4771,13 @@ snapshots:
       picomatch: 4.0.7
       scule: 1.3.0
       tinyglobby: 0.2.17
-      unplugin: 3.3.0(esbuild@0.25.12)(rollup@4.63.1)(vite@6.4.3(@types/node@22.20.1))
+      unplugin: 3.3.0(esbuild@0.25.12)(rollup@4.63.1)(vite@6.4.3(@types/node@22.20.1)(yaml@2.9.0))
       unplugin-utils: 0.3.2
       vue: 3.5.42(typescript@5.9.3)
     optionalDependencies:
       '@vue/compiler-sfc': 3.5.42
       pinia: 4.0.3(@vue/devtools-api@8.2.1)(typescript@5.9.3)(vue@3.5.42(typescript@5.9.3))
-      vite: 6.4.3(@types/node@22.20.1)
+      vite: 6.4.3(@types/node@22.20.1)(yaml@2.9.0)
     transitivePeerDependencies:
       - '@farmfe/core'
       - '@rspack/core'
@@ -4808,4 +4817,6 @@ snapshots:
 
   ws@8.21.3: {}
 
+  yaml@2.9.0: {}
+
   zwitch@2.0.4: {}

frontend/src/features/editor/noteMetadata.spec.ts

@@ -1,4 +1,5 @@
 import { expect, it } from 'vitest'
+import { parseDocument } from 'yaml'
 import { splitNoteMetadata, updateMetadataTags } from './noteMetadata'
 
 it('renders legacy properties and saves real frontmatter without losing other fields', () => {
@@ -8,7 +9,6 @@ it('renders legacy properties and saves real frontmatter without losing other fi
   expect(metadata.body).toBe('\n# 正文\n')
   const prefix = updateMetadataTags(metadata, ['编程', '学习', '学习'])
   expect(prefix).toContain('embedding_local_only: true')
-  expect(prefix).toContain('tags: ["编程","学习"]')
   expect(prefix.startsWith('---\n')).toBe(true)
   expect(splitNoteMetadata(prefix + metadata.body)!.tags).toEqual(['编程', '学习'])
 })
@@ -16,3 +16,39 @@ it('renders legacy properties and saves real frontmatter without losing other fi
 it('does not mistake ordinary Markdown for metadata', () => {
   expect(splitNoteMetadata('---\nA paragraph\n---\n')).toBeNull()
 })
+
+it.each(['- python\n- rust', '  - python\n  - rust', '[python, rust]'])('replaces the complete YAML tag list: %s', (list) => {
+  const metadata = splitNoteMetadata(`---\ntitle: Demo\ntags:\n${list.startsWith('[') ? '  ' : ''}${list}\nextra:\n  enabled: true # keep this\n---\n# Body\n`)!
+  expect(metadata.tags).toEqual(['python', 'rust'])
+  const prefix = updateMetadataTags(metadata, [...metadata.tags, 'new'])
+  const updated = splitNoteMetadata(prefix + metadata.body)!
+  expect(updated.tags).toEqual(['python', 'rust', 'new'])
+  expect(updated.body).toBe('# Body\n')
+  const document = parseDocument(updated.yaml)
+  expect(document.errors).toEqual([])
+  expect(document.toJS().extra).toEqual({ enabled: true })
+  expect(prefix).toContain('# keep this')
+  expect(splitNoteMetadata(updateMetadataTags(updated, []))!.tags).toEqual([])
+})
+
+it('preserves quoted commas, escapes, multiline titles and nested properties', () => {
+  const tags = ['a,b', 'quote"tag', 'path\\tag', 'true']
+  const metadata = splitNoteMetadata(`---\ntitle: |\n  A multiline\n  title\ntags: ${JSON.stringify(tags)}\nextra: {count: 2, enabled: false}\n---\n正文`)!
+  expect(metadata.tags).toEqual(tags)
+  const updated = splitNoteMetadata(updateMetadataTags(metadata, tags) + metadata.body)!
+  expect(updated.tags).toEqual(tags)
+  expect(updated.title).toBe(metadata.title)
+  expect(parseDocument(updated.yaml).toJS().extra).toEqual({ count: 2, enabled: false })
+})
+
+it('preserves document encoding markers and tag anchors', () => {
+  const metadata = splitNoteMetadata('\uFEFF---\r\ntitle: Demo\r\ntags: &labels [python]\r\nrelated: *labels\r\n---\r\nBody')!
+  const prefix = updateMetadataTags(metadata, ['rust'])
+  expect(prefix.startsWith('\uFEFF---\r\n')).toBe(true)
+  expect(prefix.replace(/\r\n/g, '')).not.toContain('\n')
+  expect(parseDocument(splitNoteMetadata(prefix)!.yaml).toJS().related).toEqual(['rust'])
+})
+
+it.each(['tags: [broken', 'tags: [one]\ntags: [two]', 'tags: {nested: value}', 'tags: [1, true]', 'tags: [&label python]\nother: *label'])('leaves invalid or unsupported tag data in source mode: %s', (yaml) => {
+  expect(splitNoteMetadata(`---\ntitle: Demo\n${yaml}\n---\nBody`)).toBeNull()
+})

frontend/src/features/editor/noteMetadata.ts

@@ -1,23 +1,2 @@
-// TODO(desktop): 第三阶段顶部「段落 → 导入为笔记属性」复用属性解析边界，
+export { splitNoteMetadata, updateMetadataTags } from '@/utils/noteMetadata'
-// 补齐无损 YAML、冲突合并与可撤销事务；见 docs/contracts/Tauri-Rust桌面客户端需求说明-第三阶段.md。
+export type { NoteMetadata } from '@/utils/noteMetadata'
-export interface NoteMetadata { prefix: string; yaml: string; body: string; title: string; tags: string[] }
-
-export function splitNoteMetadata(source: string): NoteMetadata | null {
-  const match = source.match(/^\uFEFF?(---|\*\*\*)[ \t]*\r?\n([\s\S]*?)\r?\n(?:-{3,}|\.\.\.)[ \t]*(?:\r?\n|$)/)
-  if (!match) return null
-  const yaml = match[2]!
-  // Only recognize metadata with explicit fields, not ordinary thematic breaks.
-  const title = yaml.match(/^title:[ \t]*(.*)$/m)?.[1]?.trim() ?? ''
-  const rawTags = yaml.match(/^tags:[ \t]*(.*)$/m)?.[1]?.trim()
-  if (!title && rawTags === undefined) return null
-  // Complex YAML values remain editable in source mode, never partially rewritten.
-  if (/^(?:[|>]|\{)/.test(title) || (rawTags === '' && /^\s+-\s/m.test(yaml))) return null
-  const tags = rawTags?.replace(/^\[|\]$/g, '').split(',').map(tag => tag.trim().replace(/^['"]|['"]$/g, '')).filter(Boolean) ?? []
-  return { prefix: match[0], yaml, body: source.slice(match[0].length), title: title.replace(/^['"]|['"]$/g, ''), tags }
-}
-
-export function updateMetadataTags(metadata: NoteMetadata, tags: string[]): string {
-  const line = `tags: ${JSON.stringify([...new Set(tags)])}`
-  const yaml = /^tags:/m.test(metadata.yaml) ? metadata.yaml.replace(/^tags:.*$/m, () => line) : `${metadata.yaml}\n${line}`
-  return `---\n${yaml.trim()}\n---\n`
-}

frontend/src/services/workspaceService.spec.ts

@@ -50,6 +50,25 @@ afterEach(() => {
 })
 
 describe('workspaceService backend adapter', () => {
+  it.each([
+    ['tags:\n- python\n- rust', { tags: ['python', 'rust'] }],
+    ['tags: []', { tags: [] }],
+    ['tags:', { tags: [] }],
+    ['tags: ["a,b", rust]', { tags: ['a,b', 'rust'] }],
+    ['title: Demo', {}],
+    ['tags: [broken', {}],
+  ])('saves explicit metadata tags with the same Markdown snapshot: %s', async (yaml, tagPayload) => {
+    const fetchMock = vi.mocked(fetch)
+    fetchMock.mockImplementation(async (input) => String(input) === '/api/workspace/open'
+      ? jsonResponse(workspaceSnapshot) : jsonResponse({}))
+    await workspaceService.openVault('C:\\data\\vault')
+    const markdown = `---\n${yaml}\n---\n# Body\n`
+    await workspaceService.saveFileContent('/课程/操作系统.md', markdown)
+    const patchCall = fetchMock.mock.calls.find(([, init]) => init?.method === 'PATCH')
+    expect(String(patchCall?.[0])).toBe('/api/notes/note-os')
+    expect(JSON.parse(String(patchCall?.[1]?.body))).toEqual({ markdown, ...tagPayload })
+  })
+
   it('opens the configured Vault and reads/saves Markdown through Note API', async () => {
     const fetchMock = vi.mocked(fetch)
     fetchMock.mockImplementation(async (input, init) => {

frontend/src/services/workspaceService.ts

@@ -9,6 +9,7 @@ import type {
 import apiClient from './apiClient'
 import { t } from '@/i18n'
 import * as noteService from './noteService'
+import { splitNoteMetadata } from '@/utils/noteMetadata'
 
 /** Web 联调只连接 AI Core 配置的单一 Vault；多 Vault 选择由 Tauri Host 接管。 */
 export interface VaultInfo {
@@ -122,7 +123,12 @@ export async function getNoteId(filePath: string): Promise<string> {
 }
 
 export async function saveFileContent(filePath: string, content: string): Promise<void> {
-  await noteService.updateNote(await requireNoteId(filePath), { markdown: content })
+  const metadata = splitNoteMetadata(content)
+  await noteService.updateNote(await requireNoteId(filePath), {
+    markdown: content,
+    // Explicit [] clears the index; absent tags retain API-managed tags.
+    ...(metadata?.hasTags ? { tags: metadata.tags } : {}),
+  })
 }
 
 export async function createFile(

frontend/src/utils/noteMetadata.ts

@@ -0,0 +1,54 @@
+import { isMap, isScalar, isSeq, parseDocument } from 'yaml'
+
+export interface NoteMetadata {
+  prefix: string
+  yaml: string
+  body: string
+  title: string
+  tags: string[]
+  hasTags: boolean
+}
+
+function parseProperties(yaml: string) {
+  const document = parseDocument(yaml)
+  // Unsupported YAML stays available in source mode without partial rewriting.
+  if (document.errors.length || document.warnings.length || !isMap(document.contents)) return null
+  return document
+}
+
+export function splitNoteMetadata(source: string): NoteMetadata | null {
+  const match = source.match(/^\uFEFF?(---|\*\*\*)[ \t]*\r?\n([\s\S]*?)\r?\n(?:-{3,}|\.\.\.)[ \t]*(?:\r?\n|$)/)
+  if (!match) return null
+  const yaml = match[2]!
+  const document = parseProperties(yaml)
+  if (!document || (!document.has('title') && !document.has('tags'))) return null
+  const title = document.get('title') ?? ''
+  if (typeof title !== 'string') return null
+  const tagNode = document.get('tags', true)
+  let tags: string[] = []
+  if (isSeq(tagNode)) {
+    // Do not remove anchored list items that other properties may reference.
+    if (!tagNode.items.every(item => isScalar(item) && typeof item.value === 'string' && !item.anchor)) return null
+    tags = tagNode.items.map(item => (item as { value: string }).value)
+  } else if (isScalar(tagNode)) {
+    if (typeof tagNode.value === 'string') tags = tagNode.value.split(',').map(tag => tag.trim()).filter(Boolean)
+    else if (tagNode.value !== null) return null
+  } else if (tagNode !== undefined) return null
+  return { prefix: match[0], yaml, body: source.slice(match[0].length), title, tags, hasTags: document.has('tags') }
+}
+
+export function updateMetadataTags(metadata: NoteMetadata, tags: string[]): string {
+  const document = parseProperties(metadata.yaml)
+  if (!document) throw new Error('Invalid note metadata')
+  const previous = document.get('tags', true)
+  const replacement = document.createNode([...new Set(tags)])
+  if (isScalar(previous) || isSeq(previous)) {
+    replacement.anchor = previous.anchor
+    replacement.comment = previous.comment
+    replacement.commentBefore = previous.commentBefore
+  }
+  document.set('tags', replacement)
+  const newline = metadata.prefix.includes('\r\n') ? '\r\n' : '\n'
+  const prefix = `---\n${document.toString()}---\n`.replace(/\n/g, newline)
+  return (metadata.prefix.startsWith('\uFEFF') ? '\uFEFF' : '') + prefix
+}