---
phase: 32-state-update-optimization
plan: 03
subsystem: ui
tags: [react, performance, state-colocation, memo]

# Dependency graph
requires:
  - phase: 32-state-update-optimization
    provides: Research identifying loading state re-renders as performance issue
provides:
  - Self-contained JKResyncButton component with colocated loading state
  - Self-contained JKVideoButton component with colocated loading state
  - Simplified JKSessionScreen without video/resync loading state
affects: [future button components, state colocation patterns]

# Tech tracking
tech-stack:
  added: []
  patterns:
    - "State colocation: Loading state lives in component that uses it"
    - "React.memo wrapper on self-contained components"
    - "PropTypes for component documentation"

key-files:
  created:
    - jam-ui/src/components/client/JKResyncButton.js
    - jam-ui/src/components/client/JKVideoButton.js
  modified:
    - jam-ui/src/components/client/JKSessionScreen.js

key-decisions:
  - "Colocated loading state in button components to prevent parent re-renders"
  - "memo() wrapper on both buttons for render optimization"
  - "Preserved original behavior: 10-second video timeout, silent resync success"

patterns-established:
  - "Button components with internal loading state pattern"
  - "Parent passes callbacks, child manages UI state"
  - "displayName for React DevTools debugging"

# Metrics
duration: 3min
completed: 2026-03-05
---

# Phase 32 Plan 03: Loading State Colocation Summary

**Extracted video and resync buttons with colocated loading state using React.memo, eliminating parent re-renders**

## Performance

- **Duration:** 3 minutes
- **Started:** 2026-03-05T19:33:34Z
- **Completed:** 2026-03-05T19:36:40Z
- **Tasks:** 3
- **Files modified:** 3

## Accomplishments
- Created self-contained JKResyncButton with local loading state
- Created self-contained JKVideoButton with local loading state
- Removed videoLoading and resyncLoading state from JKSessionScreen
- Loading state changes no longer trigger parent re-renders
- Simplified JKSessionScreen by 91 lines of code

## Task Commits

Each task was committed atomically:

1. **Task 1: Create JKResyncButton component** - `e35bed21e` (feat)
2. **Task 2: Create JKVideoButton component** - `207598940` (feat)
3. **Task 3: Refactor JKSessionScreen to use extracted components** - `f5bd1b1cd` (refactor)

## Files Created/Modified

**Created:**
- `jam-ui/src/components/client/JKResyncButton.js` - Self-contained resync button with colocated loading state, memo wrapper, error handling
- `jam-ui/src/components/client/JKVideoButton.js` - Self-contained video button with colocated loading state, memo wrapper, 10-second timeout

**Modified:**
- `jam-ui/src/components/client/JKSessionScreen.js` - Uses new button components, removed videoLoading/resyncLoading state, removed handleVideoClick/handleResync functions, removed unused icon imports (-91 lines)

## Decisions Made

**1. State colocation over prop drilling**
- Loading state lives in the button component that uses it
- Parent doesn't need to know about loading state
- Prevents parent re-renders when loading state changes
- Follows Kent C. Dodds state colocation principle

**2. memo() wrapper on both components**
- Prevents re-renders from parent prop stability
- Combined with colocated state = zero parent impact
- displayName added for React DevTools debugging

**3. Preserved original behavior**
- Video button: 10-second loading timeout (prevents multiple clicks)
- Resync button: Silent success, toast on error
- Same error handling logic as original implementation
- Same permission checks (canVideo, upgrade prompt)

**4. PropTypes for documentation**
- Documents expected props for maintainability
- Runtime validation in development mode

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered

None - straightforward extraction of button components with colocated state.

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness

**Ready for:**
- Phase 32 Plan 04: Debounce optimization (remove debounce recreation)
- Further state colocation opportunities in other components

**Performance impact:**
- Eliminates 2 state updates triggering JKSessionScreen re-renders
- Button loading states isolated to individual components
- Part of comprehensive re-render reduction strategy (Phase 32)

**Pattern established:**
- Self-contained button components with local state
- Can be replicated for other buttons with loading states
- Example: record button, broadcast button, attach button

---
*Phase: 32-state-update-optimization*
*Completed: 2026-03-05*
