Refactoring Code with Lovable Without Losing Functionality

Why refactoring in Lovable risks breaking existing functionality

Refactoring means changing how code is organized without changing what it does. In a traditional IDE, a developer can carefully rename variables, extract components, and move files while running tests after each change. In Lovable, the AI makes all these changes at once based on your prompt — and it does not run tests between steps. The biggest risk is that the AI interprets 'refactor' as permission to rewrite broadly. When you ask it to extract a component, it may also rename variables, change prop interfaces, or restructure adjacent files to match its preferred pattern. These cascading changes can break functionality in subtle ways that are not immediately visible — a form might stop validating, a button might lose its click handler, or routing might silently break. Lovable also has the '70% problem' — the AI gets most of the refactor right but misses edge cases, error handlers, or conditional logic that existed in the original code. A component that handled loading, error, and empty states might get refactored into one that only handles the success case.

• AI rewrites too broadly — it changes adjacent files and components that were not mentioned in the prompt
• Edge case logic dropped — error handling, loading states, and conditional branches are removed during restructuring
• Import paths broken — renaming or moving files breaks import statements in files that reference them
• Props interface changed — the refactored component has different props than what parent components pass
• State management disrupted — lifting or moving state changes which components re-render and when

Error messages you might see

Before you start

• A working Lovable project with features you want to restructure
• A clear list of what you want to change and what must stay the same
• GitHub connected for backup (strongly recommended before any refactoring)
• Version history available with a recent working version to revert to if needed

How to fix it

// Jumping straight into refactoring without analysis
// Agent Mode prompt: "Refactor my dashboard page"
// Result: AI changes 8 files, breaks 3 features

// Using Plan Mode to analyze first (1 credit, no code changes)
// Plan Mode prompt:
// "I want to extract the user profile card from
//  @src/pages/Dashboard.tsx into a separate
//  @src/components/UserProfileCard.tsx component.
//  Analyze:
//  1. What props does the extracted component need?
//  2. What state from Dashboard does it depend on?
//  3. Which other files reference this UI section?
//  4. What could break during this extraction?
//  Do not modify any code — just give me the analysis."

// No AGENTS.md — the AI has no constraints during refactoring

// Add to AGENTS.md before refactoring:
//
// ## Refactoring Constraints
//
// During the current refactoring:
// - DO NOT modify: src/App.tsx, src/integrations/*, vite.config.ts
// - PRESERVE all form validation logic exactly as-is
// - PRESERVE all error handling and loading states
// - PRESERVE all RLS policies and Supabase query filters
// - PRESERVE the existing prop interfaces unless explicitly asked to change them
// - After extracting a component, update ALL import statements in ALL files
//   that referenced the original code
// - Test the affected features after each change before proceeding

// Single massive refactoring prompt — high risk of breaking things
// "Refactor the entire Dashboard page: extract the sidebar into
//  its own component, move the chart section to a separate file,
//  rename all the state variables to follow camelCase convention,
//  and restructure the grid layout to use CSS Grid instead of flexbox"

// Sequential incremental prompts — each one is verifiable
//
// Prompt 1:
// "Extract the sidebar JSX from @src/pages/Dashboard.tsx into
//  a new @src/components/DashboardSidebar.tsx component.
//  Pass the navigation items as a prop. Update the import
//  in Dashboard.tsx. Do not change anything else."
// → Test sidebar navigation still works
//
// Prompt 2:
// "Extract the chart section from @src/pages/Dashboard.tsx into
//  @src/components/RevenueChart.tsx. Pass the chart data as a prop.
//  Keep the data fetching in Dashboard.tsx."
// → Test chart still displays correctly
//
// Prompt 3:
// "In @src/pages/Dashboard.tsx, replace the flexbox layout
//  with CSS Grid: grid-cols-1 md:grid-cols-[250px_1fr].
//  Keep all existing content and components unchanged."
// → Test layout on both mobile and desktop

Complete code example

1# Safe Refactoring Protocol
2
3## Before Any Refactoring
4
51. List ALL files that will be affected by the change
62. List ALL features that must continue working after the change
73. Identify ALL import statements that reference the files being changed
84. Confirm the plan with the user before executing
9
10## During Refactoring
11
121. Change ONE component or file at a time
132. After each change, verify:
14   - No broken imports (Module not found errors)
15   - No missing props (TypeScript type errors)
16   - No dropped functionality (features still work in preview)
173. Update ALL import paths in ALL files that reference moved/renamed files
184. Preserve ALL:
19   - Error handling (try/catch, error states)
20   - Loading states (loading spinners, skeleton screens)
21   - Null/undefined guards (optional chaining, fallback values)
22   - Form validation logic
23   - Authentication checks
24   - RLS policies and Supabase query filters
25
26## After Refactoring
27
281. Run a TypeScript check to catch any type errors
292. Test all pages that use the refactored components
303. Check browser console for any new warnings or errors
31
32## Never During Refactoring
33
34- Never rewrite a component from scratch — modify the existing code
35- Never change prop interfaces without updating all parent components
36- Never remove error handling, even if it 'simplifies' the code
37- Never combine multiple refactoring steps into a single task

Best practices to prevent this

• Always use Plan Mode to analyze the impact of a refactoring before executing it in Agent Mode
• Add preservation rules to AGENTS.md listing files and features that must not change during the refactoring
• Refactor one component at a time — never ask the AI to refactor an entire page or multiple files at once
• Test in the live preview after every single refactoring step — catch breaks immediately, not after stacking more changes
• If a refactoring step breaks something, revert using version history instead of trying to fix the break
• Keep error handling, loading states, and validation logic intact — these are the most commonly dropped pieces during refactoring
• Connect to GitHub before refactoring — it provides a commit-level backup for every change the AI makes
• Use specific file references with @ syntax to limit the scope of each refactoring prompt

Still stuck?

Copy one of these prompts to get a personalized, step-by-step explanation.

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