docs: add ux guidelines

docs/UX.md

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+# Comprehensive UX Practices for Web Applications
+
+## Introduction
+
+This document consolidates many of the most important practical UX principles for modern web applications.
+
+---
+
+# 1. Core UX Principles
+
+## 1.1 Visibility of System Status
+
+Users should always understand:
+
+* What the system is doing
+* Whether an action succeeded
+* Whether work is still in progress
+* Whether an error occurred
+
+### Good Practices
+
+* Show loading indicators immediately
+* Show success confirmations after important actions
+* Show inline validation messages
+* Display progress for long-running tasks
+* Use skeleton loading states instead of blank screens
+* Prevent silent failures
+* Avoid ambiguous UI states
+
+### Bad Practices
+
+* Buttons with no feedback after clicking
+* Infinite spinners without explanation
+* Hidden background operations
+* Saving without visible confirmation
+
+---
+
+## 1.2 Predictability and Consistency
+
+Users build mental models quickly.
+
+Breaking established expectations increases cognitive load and causes mistakes.
+
+### Good Practices
+
+* Use consistent layouts
+* Keep interaction patterns stable
+* Reuse common UI conventions
+* Keep naming and terminology consistent
+* Use standard keyboard shortcuts
+* Make similar components behave similarly
+
+### Bad Practices
+
+* Different button styles for identical actions
+* Inconsistent navigation behavior
+* Custom controls that ignore platform conventions
+* Unexpected modal behavior
+
+---
+
+## 1.3 Recognition Over Recall
+
+Interfaces should minimize memory requirements.
+
+Users should recognize options instead of remembering information.
+
+### Good Practices
+
+* Show recent searches
+* Use autocomplete
+* Display contextual hints
+* Preserve previously entered values
+* Use visible labels
+* Keep important actions visible
+
+### Bad Practices
+
+* Placeholder-only labels
+* Hidden functionality
+* Requiring users to remember previous state
+* Removing useful context during workflows
+
+---
+
+## 1.4 Error Prevention
+
+Preventing mistakes is better than handling mistakes.
+
+### Good Practices
+
+* Disable impossible actions
+* Validate input early
+* Warn before destructive operations
+* Use constrained input formats
+* Use safe defaults
+* Prefer undo over confirmation dialogs
+
+### Bad Practices
+
+* Destructive actions near common actions
+* Easy accidental deletion
+* Poor validation timing
+* Irreversible operations without recovery
+
+---
+
+# 2. Input and Form UX
+
+Forms are one of the most important and failure-prone areas in web applications.
+
+---
+
+## 2.1 Input Focus Behavior
+
+### Good Practices
+
+* Autofocus the primary field when appropriate
+* Preserve focus during rerenders
+* Preserve cursor position
+* Support keyboard-first workflows
+* Use logical tab ordering
+
+### Auto-Selecting Input Text
+
+Auto-selecting text on focus is context-dependent.
+
+### Good Use Cases
+
+* Quantity fields
+* Rename dialogs
+* Editable defaults
+* Quick replacement workflows
+* Temporary values users often replace entirely
+
+### Bad Use Cases
+
+* Long textareas
+* Complex text editing
+* Fields users commonly partially edit
+* Rich text editing
+
+### Principle
+
+Only auto-select when full replacement is more likely than partial editing.
+
+---
+
+## 2.2 Labels and Placeholders
+
+### Good Practices
+
+* Always use visible labels
+* Use placeholders only as supplementary examples
+* Keep labels visible after typing
+* Associate labels correctly for accessibility
+
+### Bad Practices
+
+* Placeholder-only forms
+* Ambiguous labels
+* Labels that disappear during editing
+
+---
+
+## 2.3 Validation
+
+### Recommended Validation Timing
+
+| Validation Type     | Timing    |
+| ------------------- | --------- |
+| Format validation   | Immediate |
+| Semantic validation | On blur   |
+| Server validation   | On submit |
+
+### Good Practices
+
+* Show errors near the relevant field
+* Explain how to fix issues
+* Preserve entered values after errors
+* Validate incrementally
+* Use clear language
+
+### Bad Practices
+
+* Generic “Invalid input” messages
+* Clearing form data after errors
+* Delayed validation surprises
+* Validation that interrupts typing
+
+---
+
+## 2.4 Input Types
+
+### Good Practices
+
+Use appropriate HTML input types:
+
+* `email`
+* `tel`
+* `number`
+* `date`
+* `password`
+* `search`
+
+### Benefits
+
+* Better mobile keyboards
+* Native validation
+* Improved accessibility
+* Better autofill support
+
+---
+
+## 2.5 Form Submission
+
+### Good Practices
+
+* Enter submits forms when expected
+* Escape cancels dialogs
+* Show loading states during submission
+* Prevent duplicate submissions
+* Preserve draft state
+* Allow keyboard submission
+
+### Bad Practices
+
+* Disabled submit buttons without explanation
+* Hidden validation failures
+* Silent submission failures
+
+---
+
+## 2.6 Dropdowns and Selection UX
+
+### Good Practices
+
+* Use radio buttons for small option sets
+* Use searchable selects for large datasets
+* Prefer autocomplete for many options
+* Show selected state clearly
+
+### Bad Practices
+
+* Massive unsearchable dropdowns
+* Nested dropdown hierarchies
+* Multi-select controls without search
+
+---
+
+# 3. Navigation UX
+
+---
+
+## 3.1 Orientation
+
+Users should always know:
+
+* Where they are
+* How they got there
+* What they can do next
+* How to go back
+
+### Good Practices
+
+* Highlight active navigation
+* Use breadcrumbs when helpful
+* Use meaningful page titles
+* Preserve navigation consistency
+
+---
+
+## 3.2 Navigation Structure
+
+### Good Practices
+
+* Keep hierarchy shallow
+* Group related actions
+* Use descriptive names
+* Keep primary actions stable
+
+### Bad Practices
+
+* Deep nesting
+* Ambiguous navigation labels
+* Constantly moving actions
+
+---
+
+## 3.3 URL Design
+
+### Good Practices
+
+* Use readable URLs
+* Make URLs shareable
+* Preserve app state in URLs when useful
+* Support browser history correctly
+
+### Bad Practices
+
+* Opaque generated URLs
+* Broken back button behavior
+* Losing state during navigation
+
+---
+
+# 4. Interaction Design
+
+---
+
+## 4.1 Click Targets
+
+### Good Practices
+
+* Large clickable areas
+* Adequate spacing between actions
+* Clear hover/focus states
+* Touch-friendly sizing
+
+### Bad Practices
+
+* Tiny clickable regions
+* Overlapping interactive elements
+* Hidden hit areas
+
+---
+
+## 4.2 Feedback
+
+Every interaction should produce feedback.
+
+### Good Practices
+
+* Hover states
+* Active states
+* Loading indicators
+* Success states
+* Error states
+* Optimistic updates when appropriate
+
+### Bad Practices
+
+* Dead-feeling interfaces
+* Invisible processing
+* Delayed reactions
+
+---
+
+## 4.3 Destructive Actions
+
+### Good Practices
+
+* Require confirmation for dangerous actions
+* Prefer undo systems
+* Visually distinguish destructive buttons
+* Separate destructive actions spatially
+
+### Bad Practices
+
+* Immediate irreversible deletion
+* Dangerous actions near common actions
+* Ambiguous destructive wording
+
+---
+
+## 4.4 Modal UX
+
+### Good Practices
+
+* Trap keyboard focus
+* Support Escape to close
+* Restore focus after closing
+* Prevent background interaction
+* Keep modal purpose focused
+
+### Bad Practices
+
+* Nested modals
+* Full workflows inside modals
+* Losing unsaved work accidentally
+
+---
+
+# 5. Performance UX
+
+Performance is a UX feature.
+
+Users interpret slowness as unreliability.
+
+---
+
+## 5.1 Perceived Performance
+
+### Good Practices
+
+* Show immediate visual response
+* Use optimistic UI updates
+* Preload likely next content
+* Stream content progressively
+* Use skeleton loaders
+
+### Bad Practices
+
+* Blank screens during loading
+* Long blocking operations
+* Frozen interfaces
+
+---
+
+## 5.2 Layout Stability
+
+### Good Practices
+
+* Prevent layout shift
+* Reserve image dimensions
+* Avoid moving buttons during loading
+* Keep skeletons aligned with final layout
+
+### Bad Practices
+
+* Jumping content
+* Shifting controls
+* Reflow-heavy rendering
+
+---
+
+## 5.3 Responsiveness
+
+### Good Practices
+
+* Keep UI interactive during async operations
+* Avoid blocking the main thread
+* Debounce expensive operations
+* Virtualize large lists
+
+### Bad Practices
+
+* UI freezes
+* Excessive rerenders
+* Laggy typing experiences
+
+---
+
+# 6. Accessibility
+
+Accessibility improves usability for everyone.
+
+---
+
+## 6.1 Keyboard Accessibility
+
+### Good Practices
+
+* Full keyboard navigation
+* Visible focus indicators
+* Logical tab order
+* Keyboard shortcuts for power users
+
+### Bad Practices
+
+* Mouse-only workflows
+* Hidden focus state
+* Keyboard traps
+
+---
+
+## 6.2 Semantic HTML
+
+### Good Practices
+
+* Use proper semantic elements
+* Use buttons for actions
+* Use links for navigation
+* Use headings correctly
+
+### Bad Practices
+
+* Clickable divs without accessibility support
+* Fake buttons
+* Missing semantic structure
+
+---
+
+## 6.3 Visual Accessibility
+
+### Good Practices
+
+* Sufficient color contrast
+* Support reduced motion
+* Avoid color-only communication
+* Use scalable typography
+
+### Bad Practices
+
+* Tiny text
+* Low contrast interfaces
+* Flashing animations
+
+---
+
+## 6.4 Screen Reader Support
+
+### Good Practices
+
+* Proper labels
+* Meaningful alt text
+* ARIA only when necessary
+* Correct live regions for updates
+
+### Bad Practices
+
+* Unlabeled controls
+* Excessive ARIA misuse
+* Non-announced state changes
+
+---
+
+# 7. Enterprise Application UX
+
+Enterprise UX differs significantly from marketing-oriented consumer interfaces.
+
+Power users often prioritize efficiency over visual minimalism.
+
+---
+
+## 7.1 Dense Information Design
+
+### Good Practices
+
+* Efficient data density
+* Resizable tables
+* Sticky headers
+* Multi-column layouts
+* High information throughput
+
+### Bad Practices
+
+* Excessive whitespace
+* Oversimplified dashboards
+* Hidden operational controls
+
+---
+
+## 7.2 Table UX
+
+### Good Practices
+
+* Sorting
+* Filtering
+* Column resizing
+* Pagination or virtualization
+* Keyboard navigation
+* Export functionality
+* Persistent user preferences
+
+### Bad Practices
+
+* Non-sortable enterprise tables
+* Horizontal scrolling nightmares
+* Missing filtering
+
+---
+
+## 7.3 Power User Workflows
+
+### Good Practices
+
+* Keyboard shortcuts
+* Bulk actions
+* Batch editing
+* Command palettes
+* State persistence
+* Fast navigation
+
+### Bad Practices
+
+* Forced wizard workflows
+* Excessive confirmations
+* Repetitive manual work
+
+---
+
+# 8. Mobile UX
+
+---
+
+## 8.1 Touch Design
+
+### Good Practices
+
+* Large touch targets
+* Thumb-friendly layouts
+* Avoid hover dependencies
+* Mobile-friendly spacing
+
+### Bad Practices
+
+* Tiny controls
+* Hover-only interactions
+* Precision-dependent gestures
+
+---
+
+## 8.2 Mobile Forms
+
+### Good Practices
+
+* Mobile keyboard optimization
+* Minimal typing
+* Autofill support
+* Step-by-step flows when necessary
+
+### Bad Practices
+
+* Long complex forms
+* Tiny input fields
+* Excessive required typing
+
+---
+
+# 9. Cognitive Psychology and UX
+
+---
+
+## 9.1 Hick’s Law
+
+More choices increase decision time.
+
+### Applications
+
+* Reduce unnecessary options
+* Group related actions
+* Prioritize primary actions
+
+---
+
+## 9.2 Fitts’s Law
+
+Closer and larger targets are easier to use.
+
+### Applications
+
+* Large primary buttons
+* Edge/corner placement for important actions