fix(frontend): save button always disabled on System Prompts page

Root cause: PromptEditor useEffect synced localPrompts back to match prompts after every keystroke, making isDirty() always false.

- Delegate disabled control to parent via hasChanges prop (no local sync)

- Derive currentPrompts synchronously to avoid empty-textarea flash

- Add key={selectedProfile} for clean remount on profile switch

- Update PromptEditor tests for new hasChanges prop

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

frontend/src/components/PromptEditor.tsx

@@ -1,9 +1,10 @@
-import React, { useState, useEffect, useCallback } from 'react'
+import React, { useState } from 'react'
 import { RotateCcw, AlertTriangle } from 'lucide-react'
 
 export interface PromptEditorProps {
   profileName: string
   prompts: Record<string, string>
+  hasChanges: boolean
   isSaving: boolean
   onUpdate: (step: string, template: string) => void
   onSave: () => void
@@ -33,6 +34,7 @@ const findUnknownPlaceholders = (template: string, stepKey: string): string[] =>
 export const PromptEditor: React.FC<PromptEditorProps> = ({
   profileName,
   prompts,
+  hasChanges,
   isSaving,
   onUpdate,
   onSave,
@@ -40,9 +42,9 @@ export const PromptEditor: React.FC<PromptEditorProps> = ({
   onResetAll,
   onCancel,
 }) => {
-  const [localPrompts, setLocalPrompts] = useState<Record<string, string>>({})
+  const [localPrompts, setLocalPrompts] = useState<Record<string, string>>({ ...prompts })
 
-  useEffect(() => {
+  React.useEffect(() => {
     setLocalPrompts({ ...prompts })
   }, [prompts])
 
@@ -63,10 +65,6 @@ export const PromptEditor: React.FC<PromptEditorProps> = ({
     }
   }
 
-  const isDirty = useCallback(() => {
-    return STEPS.some((step) => localPrompts[step.key] !== prompts[step.key])
-  }, [localPrompts, prompts])
-
   return (
     <div className="bg-white rounded-lg border border-gray-200 shadow-sm p-6 space-y-6">
       <div className="flex items-center gap-2 border-b border-gray-200 pb-3">
@@ -136,7 +134,7 @@ export const PromptEditor: React.FC<PromptEditorProps> = ({
         <button
           type="button"
           onClick={onSave}
-          disabled={isSaving || !isDirty()}
+          disabled={isSaving || !hasChanges}
           className="px-4 py-2 bg-blue-600 text-white text-sm font-medium rounded hover:bg-blue-700 focus:outline-none focus:ring-2 focus:ring-blue-500 focus:ring-offset-2 disabled:opacity-50 disabled:cursor-not-allowed disabled:hover:bg-blue-600 transition-all duration-200"
         >
           {isSaving ? 'Saving...' : 'Save Changes'}

frontend/src/pages/SystemPromptsPage.tsx

@@ -50,7 +50,9 @@ export const SystemPromptsPage: React.FC = () => {
       setEditPrompts(profileData.prompts)
       setHasChanges(false)
     }
-  }, [profileData])
+  }, [profileData]) // eslint-disable-line react-hooks/exhaustive-deps
+
+  const currentPrompts = hasChanges ? editPrompts : (profileData?.prompts ?? {})
 
   const handleSelectProfile = (name: string) => {
     if (selectedProfile === name) {
@@ -214,8 +216,10 @@ export const SystemPromptsPage: React.FC = () => {
               <>
                 <PlaceholderDocs />
                 <PromptEditor
+                  key={selectedProfile}
                   profileName={selectedProfile}
-                  prompts={editPrompts}
+                  prompts={currentPrompts}
+                  hasChanges={hasChanges}
                   isSaving={isSaving}
                   onUpdate={handleUpdate}
                   onSave={handleSave}

frontend/src/test/components/PromptEditor.test.tsx

@@ -11,6 +11,7 @@ const mockPrompts: Record<string, string> = {
 const defaultProps = {
   profileName: 'A',
   prompts: mockPrompts,
+  hasChanges: false,
   isSaving: false,
   onUpdate: vi.fn(),
   onSave: vi.fn(),
@@ -85,11 +86,7 @@ describe('PromptEditor', () => {
   })
 
   it('calls onSave when "Save Changes" button is clicked', () => {
-    render(<PromptEditor {...defaultProps} />)
+    render(<PromptEditor {...defaultProps} hasChanges={true} />)
-
-    // The Save button is disabled when not dirty, so we need to change something first
-    const textareas = screen.getAllByRole('textbox')
-    fireEvent.change(textareas[0], { target: { value: 'Modified decompose template' } })
 
     const saveButton = screen.getByRole('button', { name: /save changes/i })
     expect(saveButton).not.toBeDisabled()