SKILL.md
$2a
if (error) return ;
if (loading && !data) return ;
if (!data?.items.length) return ;
return ;
// WRONG - Shows spinner even when we have cached data
if (loading) return <LoadingState />; // Flashes on refetch!
### Loading State Decision Tree
Is there an error?
→ Yes: Show error state with retry option
→ No: Continue
Is it loading AND we have no data?
→ Yes: Show loading indicator (spinner/skeleton)
→ No: Continue
Do we have data?
→ Yes, with items: Show the data
→ Yes, but empty: Show empty state
→ No: Show loading (fallback)
### Skeleton vs Spinner
Use Skeleton When
Use Spinner When
Known content shape
Unknown content shape
List/card layouts
Modal actions
Initial page load
Button submissions
Content placeholders
Inline operations
## Error Handling Patterns
### The Error Handling Hierarchy
- Inline error (field-level) → Form validation errors
- Toast notification → Recoverable errors, user can retry
- Error banner → Page-level errors, data still partially usable
- Full error screen → Unrecoverable, needs user action
### Always Show Errors
**CRITICAL: Never swallow errors silently.**
// CORRECT - Error always surfaced to user
const [createItem, { loading }] = useCreateItemMutation({
onCompleted: () => {
toast.success({ title: 'Item created' });
},
onError: (error) => {
console.error('createItem failed:', error);
toast.error({ title: 'Failed to create item' });
},
});
// WRONG - Error silently caught, user has no idea
const [createItem] = useCreateItemMutation({
onError: (error) => {
console.error(error); // User sees nothing!
},
});
### Error State Component Pattern
interface ErrorStateProps {
error: Error;
onRetry?: () => void;
title?: string;
}
const ErrorState = ({ error, onRetry, title }: ErrorStateProps) => (
<div className="error-state">
<Icon name="exclamation-circle" />
<h3>{title ?? 'Something went wrong'}</h3>
<p>{error.message}</p>
{onRetry && (
<Button onClick={onRetry}>Try Again</Button>
)}
</div>
);
## Button State Patterns
### Button Loading State
<Button
onClick={handleSubmit}
isLoading={isSubmitting}
disabled={!isValid || isSubmitting}
>
Submit
</Button>
### Disable During Operations
**CRITICAL: Always disable triggers during async operations.**
// CORRECT - Button disabled while loading
<Button
disabled={isSubmitting}
isLoading={isSubmitting}
onClick={handleSubmit}
>
Submit
</Button>
// WRONG - User can tap multiple times
<Button onClick={handleSubmit}>
{isSubmitting ? 'Submitting...' : 'Submit'}
</Button>
## Empty States
### Empty State Requirements
Every list/collection MUST have an empty state:
// WRONG - No empty state
return <FlatList data={items} />;
// CORRECT - Explicit empty state
return (
<FlatList
data={items}
ListEmptyComponent={<EmptyState />}
/>
);
### Contextual Empty States
// Search with no results
<EmptyState
icon="search"
title="No results found"
description="Try different search terms"
/>
// List with no items yet
<EmptyState
icon="plus-circle"
title="No items yet"
description="Create your first item"
action={{ label: 'Create Item', onClick: handleCreate }}
/>
## Form Submission Pattern
const MyForm = () => {
const [submit, { loading }] = useSubmitMutation({
onCompleted: handleSuccess,
onError: handleError,
});
const handleSubmit = async () => {
if (!isValid) {
toast.error({ title: 'Please fix errors' });
return;
}
await submit({ variables: { input: values } });
};
return (
<form>
<Input
value={values.name}
onChange={handleChange('name')}
error={touched.name ? errors.name : undefined}
/>
<Button
type="submit"
onClick={handleSubmit}
disabled={!isValid || loading}
isLoading={loading}
>
Submit
</Button>
</form>
);
};
## Anti-Patterns
### Loading States
// WRONG - Spinner when data exists (causes flash)
if (loading) return <Spinner />;
// CORRECT - Only show loading without data
if (loading && !data) return <Spinner />;
### Error Handling
// WRONG - Error swallowed
try {
await mutation();
} catch (e) {
console.log(e); // User has no idea!
}
// CORRECT - Error surfaced
onError: (error) => {
console.error('operation failed:', error);
toast.error({ title: 'Operation failed' });
}
### Button States
// WRONG - Button not disabled during submission
<Button onClick={submit}>Submit</Button>
// CORRECT - Disabled and shows loading
<Button onClick={submit} disabled={loading} isLoading={loading}>
Submit
</Button>