feat: Add update_theme functionality with UI support

Backend:
- Add PUT /api/themes/:id endpoint for updating existing themes

Store:
- Add updateTheme method to theme store

MCP:
- Add update_theme tool to modify name, description, or save current variables

UI:
- Add edit button to ThemeListItem (custom themes only)
- Add edit modal with name and description fields
- Support editing from both desktop sidebar and mobile dropdown

CLAUDE.md

@@ -0,0 +1,21 @@
+# Agent UI - Claude Code Guidelines
+
+## Commits
+- NO incluir "Co-Authored-By: Claude" en los commits
+- Commits concisos y descriptivos en inglés
+
+## Proyecto
+- Frontend: Vue 3 + TypeScript + Pinia
+- Backend: Bun + SQLite
+- MCP: @nucleoriofrio/webmcp
+
+## Herramientas MCP dinámicas
+Las herramientas MCP cambian según la página activa:
+- `/canvas` - render_html, render_vue_component, save/load components
+- `/themes` - get_design_tokens, set_theme_variable, save_theme, update_theme, etc.
+- `/components` - gestión de componentes Vue
+
+## Archivos clave
+- `frontend/src/services/tools/` - Herramientas MCP por página
+- `frontend/src/stores/theme.ts` - Store de temas
+- `server/index.ts` - API HTTP y SQLite

frontend/src/components/themes/ThemeListItem.vue

@@ -11,6 +11,7 @@ const emit = defineEmits<{
   delete: [id: string]
   clone: [id: string]
   setDefault: [id: string]
+  edit: [theme: Theme]
 }>()
 
 function getAccentColor(): string {
@@ -48,6 +49,18 @@ function getAccentColor(): string {
         </svg>
       </button>
 
+      <button
+        v-if="!theme.is_system"
+        class="action-btn"
+        @click="emit('edit', theme)"
+        title="Edit theme"
+      >
+        <svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+          <path d="M11 4H4a2 2 0 0 0-2 2v14a2 2 0 0 0 2 2h14a2 2 0 0 0 2-2v-7"/>
+          <path d="M18.5 2.5a2.121 2.121 0 0 1 3 3L12 15l-4 1 1-4 9.5-9.5z"/>
+        </svg>
+      </button>
+
       <button
         class="action-btn"
         @click="emit('clone', theme.id)"

frontend/src/pages/ThemesPage.vue

@@ -16,6 +16,10 @@ const showNewThemeModal = ref(false)
 const showCloneModal = ref(false)
 const cloneSourceId = ref<string | null>(null)
 const cloneName = ref('')
+const showEditModal = ref(false)
+const editingTheme = ref<any>(null)
+const editName = ref('')
+const editDescription = ref('')
 const fileInput = ref<HTMLInputElement | null>(null)
 
 const currentCategoryVariables = computed(() => {
@@ -58,6 +62,26 @@ async function confirmClone() {
   }
 }
 
+function handleEditTheme(theme: any) {
+  editingTheme.value = theme
+  editName.value = theme.name
+  editDescription.value = theme.description || ''
+  showEditModal.value = true
+}
+
+async function confirmEdit() {
+  if (editingTheme.value && editName.value.trim()) {
+    await store.updateTheme(editingTheme.value.id, {
+      name: editName.value.trim(),
+      description: editDescription.value.trim() || undefined
+    })
+    showEditModal.value = false
+    editingTheme.value = null
+    editName.value = ''
+    editDescription.value = ''
+  }
+}
+
 function handleSetDefault(id: string) {
   store.setDefaultTheme(id)
 }
@@ -171,6 +195,7 @@ onMounted(() => {
                   @select="(t) => { handleSelectTheme(t); mobileDropdownOpen = false }"
                   @clone="handleCloneTheme"
                   @setDefault="handleSetDefault"
+                  @edit="handleEditTheme"
                 />
               </div>
               <div v-if="store.userThemes.length > 0" class="dropdown-section">
@@ -184,6 +209,7 @@ onMounted(() => {
                   @delete="handleDeleteTheme"
                   @clone="handleCloneTheme"
                   @setDefault="handleSetDefault"
+                  @edit="handleEditTheme"
                 />
               </div>
             </div>
@@ -208,6 +234,7 @@ onMounted(() => {
             @delete="handleDeleteTheme"
             @clone="handleCloneTheme"
             @setDefault="handleSetDefault"
+            @edit="handleEditTheme"
           />
         </section>
 
@@ -222,6 +249,7 @@ onMounted(() => {
             @delete="handleDeleteTheme"
             @clone="handleCloneTheme"
             @setDefault="handleSetDefault"
+            @edit="handleEditTheme"
           />
         </section>
       </div>
@@ -366,6 +394,33 @@ onMounted(() => {
         </div>
       </div>
     </div>
+
+    <!-- Edit Modal -->
+    <div v-if="showEditModal" class="modal-overlay" @click="showEditModal = false">
+      <div class="modal" @click.stop>
+        <h3>Edit Theme</h3>
+        <div class="form-group">
+          <label>Name</label>
+          <input
+            v-model="editName"
+            type="text"
+            placeholder="Theme name"
+          />
+        </div>
+        <div class="form-group">
+          <label>Description</label>
+          <textarea
+            v-model="editDescription"
+            placeholder="Theme description (optional)"
+            rows="3"
+          ></textarea>
+        </div>
+        <div class="modal-actions">
+          <button class="btn-secondary" @click="showEditModal = false">Cancel</button>
+          <button class="btn-primary" @click="confirmEdit">Save</button>
+        </div>
+      </div>
+    </div>
   </div>
 </template>
 
@@ -820,6 +875,35 @@ onMounted(() => {
   border-color: var(--accent);
 }
 
+.form-group {
+  margin-bottom: 1rem;
+}
+
+.form-group label {
+  display: block;
+  font-size: 0.8rem;
+  font-weight: 500;
+  color: var(--text-secondary);
+  margin-bottom: 0.375rem;
+}
+
+.modal textarea {
+  width: 100%;
+  padding: 0.75rem 1rem;
+  background: var(--bg-primary);
+  border: 1px solid var(--border-color);
+  border-radius: 8px;
+  color: var(--text-primary);
+  font-size: 0.95rem;
+  font-family: inherit;
+  resize: vertical;
+}
+
+.modal textarea:focus {
+  outline: none;
+  border-color: var(--accent);
+}
+
 .modal-actions {
   display: flex;
   gap: 0.75rem;

frontend/src/services/tools/themeTools.ts

@@ -6,6 +6,7 @@ export const THEME_TOOLS = [
   'get_active_theme',
   'set_theme_variable',
   'save_theme',
+  'update_theme',
   'list_themes',
   'switch_theme',
   'set_default_theme',
@@ -212,6 +213,85 @@ export function registerThemeTools() {
     }
   )
 
+  // update_theme
+  registerTool(
+    'update_theme',
+    'Actualiza un tema existente (nombre, descripción o variables)',
+    {
+      type: 'object',
+      properties: {
+        theme: {
+          type: 'string',
+          description: 'Nombre o ID del tema a actualizar'
+        },
+        name: {
+          type: 'string',
+          description: 'Nuevo nombre para el tema (opcional)'
+        },
+        description: {
+          type: 'string',
+          description: 'Nueva descripción para el tema (opcional)'
+        },
+        saveCurrentVariables: {
+          type: 'boolean',
+          description: 'Si es true, guarda las variables actuales (con los cambios de set_theme_variable) en este tema'
+        }
+      },
+      required: ['theme']
+    },
+    async (args: { theme: string; name?: string; description?: string; saveCurrentVariables?: boolean }) => {
+      try {
+        const themeStore = useThemeStore()
+        await themeStore.fetchThemes()
+
+        // Find theme by ID or name
+        const theme = themeStore.themes.find(t =>
+          t.id === args.theme || t.name.toLowerCase() === args.theme.toLowerCase()
+        )
+
+        if (!theme) {
+          const available = themeStore.themes.map(t => t.name).join(', ')
+          return `Tema "${args.theme}" no encontrado.\nDisponibles: ${available}`
+        }
+
+        if (theme.is_system) {
+          return `No se puede modificar "${theme.name}" porque es un tema del sistema. Usa save_theme para crear una copia.`
+        }
+
+        // Build update data
+        const updateData: { name?: string; description?: string; variables?: any } = {}
+
+        if (args.name) {
+          updateData.name = args.name
+        }
+        if (args.description !== undefined) {
+          updateData.description = args.description
+        }
+        if (args.saveCurrentVariables) {
+          const variablesToSave = themeStore.previewTheme || themeStore.activeTheme?.variables
+          if (variablesToSave) {
+            updateData.variables = variablesToSave
+          }
+        }
+
+        if (Object.keys(updateData).length === 0) {
+          return 'No se especificaron cambios. Usa name, description o saveCurrentVariables.'
+        }
+
+        await themeStore.updateTheme(theme.id, updateData)
+
+        const changes = []
+        if (args.name) changes.push(`nombre: "${args.name}"`)
+        if (args.description !== undefined) changes.push('descripción actualizada')
+        if (args.saveCurrentVariables) changes.push('variables guardadas')
+
+        return `Tema "${theme.name}" actualizado:\n  ${changes.join('\n  ')}`
+      } catch (e: any) {
+        return `Error al actualizar tema: ${e.message}`
+      }
+    }
+  )
+
   // list_themes
   registerTool(
     'list_themes',

frontend/src/stores/theme.ts

@@ -138,6 +138,29 @@ export const useThemeStore = defineStore('theme', () => {
     }
   }
 
+  async function updateTheme(id: string, data: { name?: string; description?: string; variables?: ThemeVariables; metadata?: ThemeMetadata }) {
+    saving.value = true
+    try {
+      const res = await fetch(`${API_URL}/api/themes/${id}`, {
+        method: 'PUT',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify(data)
+      })
+      const result = await res.json()
+      if (result.error) {
+        error.value = result.error
+        return null
+      }
+      await fetchThemes()
+      return result
+    } catch (e) {
+      error.value = 'Error updating theme'
+      throw e
+    } finally {
+      saving.value = false
+    }
+  }
+
   async function deleteTheme(id: string) {
     try {
       const res = await fetch(`${API_URL}/api/themes/${id}`, { method: 'DELETE' })
@@ -281,6 +304,7 @@ export const useThemeStore = defineStore('theme', () => {
     fetchThemes,
     fetchDesignTokens,
     saveTheme,
+    updateTheme,
     deleteTheme,
     setDefaultTheme,
     cloneTheme,

server/index.ts

@@ -393,6 +393,47 @@ Bun.serve({
         return Response.json({ success: true }, { headers: corsHeaders })
       }
 
+      // PUT /api/themes/:id - Actualizar un tema existente
+      if (req.method === 'PUT' && !action) {
+        const theme = db.query('SELECT * FROM themes WHERE id = ?').get(id) as any
+        if (!theme) {
+          return Response.json({ error: 'Theme not found' }, { status: 404, headers: corsHeaders })
+        }
+
+        const body = await req.json()
+
+        // Build update query dynamically based on provided fields
+        const updates: string[] = []
+        const values: any[] = []
+
+        if (body.name !== undefined) {
+          updates.push('name = ?')
+          values.push(body.name)
+        }
+        if (body.description !== undefined) {
+          updates.push('description = ?')
+          values.push(body.description)
+        }
+        if (body.variables !== undefined) {
+          updates.push('variables = ?')
+          values.push(JSON.stringify(body.variables))
+        }
+        if (body.metadata !== undefined) {
+          updates.push('metadata = ?')
+          values.push(JSON.stringify(body.metadata))
+        }
+
+        if (updates.length > 0) {
+          updates.push('updated_at = CURRENT_TIMESTAMP')
+          values.push(id)
+
+          const sql = `UPDATE themes SET ${updates.join(', ')} WHERE id = ?`
+          db.run(sql, values)
+        }
+
+        return Response.json({ success: true, id }, { headers: corsHeaders })
+      }
+
       // GET /api/themes/:id - Obtener un tema
       if (req.method === 'GET' && !action) {
         const row = db.query('SELECT * FROM themes WHERE id = ?').get(id) as any