feat(magic-notes): improve tag management UI

src/main/assistant/assistant-database.test.ts

@@ -7805,8 +7805,8 @@ describe('AssistantDatabase', () => {
       const retagged = database.updateMagicNote({ noteId: work.id, tags: ['Work'], expectedRevision: work.revision })
       expect(retagged.tags).toEqual(['Work'])
       expect(retagged.revision).toBe(work.revision + 1)
-      // "Project A" lost its last note and is removed.
-      expect(database.listMagicNoteTags().map((tag) => tag.name)).not.toContain('Project A')
+       // Tags remain available after their last note link is removed.
+       expect(database.listMagicNoteTags().map((tag) => tag.name)).toContain('Project A')
       expect(() => database.updateMagicNote({ noteId: work.id, tags: [], expectedRevision: work.revision })).toThrow()
       expect(database.getMagicNote(work.id).tags).toEqual(['Work'])
 
@@ -7820,19 +7820,23 @@ describe('AssistantDatabase', () => {
       const merged = database.renameMagicNoteTag({ tagId: workTag.id, name: 'Personal' })
       expect(merged).toMatchObject({ merged: true, tag: { name: 'personal', noteCount: 3 } })
       expect(database.getMagicNote(both.id).tags).toEqual(['personal'])
-      expect(database.listMagicNoteTags()).toHaveLength(1)
+       expect(database.listMagicNoteTags().map((tag) => tag.name)).toEqual(['personal', 'Project A'])
 
       const calls = onMagicNotesChanged.mock.calls.length
       database.deleteMagicNoteTag(merged.tag.id)
       expect(onMagicNotesChanged).toHaveBeenCalledTimes(calls + 1)
-      expect(database.listMagicNoteTags()).toEqual([])
-      expect(database.getMagicNote(personal.id)).toMatchObject({ title: 'Personal', tags: [] })
-      expect(() => database.deleteMagicNoteTag(merged.tag.id)).toThrow('标签不存在')
-      expect(() => database.renameMagicNoteTag({ tagId: merged.tag.id, name: 'x' })).toThrow('标签不存在')
+       expect(database.listMagicNoteTags().map((tag) => tag.name)).toEqual(['Project A'])
+       expect(database.getMagicNote(personal.id)).toMatchObject({ title: 'Personal', tags: [] })
+       expect(() => database.deleteMagicNoteTag(merged.tag.id)).toThrow('标签不存在')
+       expect(() => database.renameMagicNoteTag({ tagId: merged.tag.id, name: 'x' })).toThrow('标签不存在')
 
-      database.updateMagicNote({ noteId: personal.id, tags: ['Solo'], expectedRevision: database.getMagicNote(personal.id).revision })
+       const empty = database.createMagicNoteTag({ name: 'Ideas' })
+       expect(empty).toEqual(expect.objectContaining({ name: 'Ideas', noteCount: 0 }))
+       expect(database.listMagicNoteTags().map((tag) => tag.name)).toContain('Ideas')
+
+       database.updateMagicNote({ noteId: personal.id, tags: ['Solo'], expectedRevision: database.getMagicNote(personal.id).revision })
       database.deleteMagicNote(personal.id)
-      expect(database.listMagicNoteTags()).toEqual([])
+       expect(database.listMagicNoteTags().map((tag) => tag.name)).toEqual(['Ideas', 'Project A', 'Solo'])
     } finally {
       database.close()
     }

src/main/assistant/assistant-database.ts

@@ -4169,13 +4169,30 @@ export class AssistantDatabase {
          FROM magic_note_tags t
          LEFT JOIN magic_note_tag_links l ON l.tag_id = t.id
          GROUP BY t.id
-         HAVING note_count > 0
          ORDER BY note_count DESC, t.name_key ASC`
       )
       .all() as MagicNoteTagRow[]
     return rows.map(toMagicNoteTag)
   }
 
+  createMagicNoteTag(input: { name: string }): MagicNoteTag {
+    const database = this.requireDatabase()
+    const now = new Date().toISOString()
+    const id = randomUUID()
+    const key = magicNoteTagKey(input.name)
+    try {
+      database.prepare(
+        `INSERT INTO magic_note_tags (id, name, name_key, created_at, updated_at)
+         VALUES (?, ?, ?, ?, ?)`
+      ).run(id, input.name, key, now, now)
+    } catch (error) {
+      if (error instanceof Error && error.message.includes('UNIQUE')) throw new Error('标签已存在')
+      throw error
+    }
+    this.options.onMagicNotesChanged?.()
+    return { id, name: input.name, noteCount: 0 }
+  }
+
   /**
    * Renames a tag across every note. When the new name matches another tag,
    * the two merge: links move to the existing tag and the old tag is removed.
@@ -4286,14 +4303,6 @@ export class AssistantDatabase {
       }
       insertLink.run(noteId, tag.id, position, now)
     })
-    this.deleteOrphanMagicNoteTags(database)
-  }
-
-  private deleteOrphanMagicNoteTags(database: DatabaseSync): void {
-    database.exec(
-      `DELETE FROM magic_note_tags
-       WHERE NOT EXISTS (SELECT 1 FROM magic_note_tag_links l WHERE l.tag_id = magic_note_tags.id)`
-    )
   }
 
   getMagicNote(noteId: string): MagicNoteDetail {
@@ -4474,7 +4483,6 @@ export class AssistantDatabase {
       if (result.changes !== 1) {
         throw new Error('笔记不存在')
       }
-      this.deleteOrphanMagicNoteTags(database)
       database.exec('COMMIT')
     } catch (error) {
       database.exec('ROLLBACK')