---
phase: 21-chat-window-fixes
plan: 01
subsystem: state-management
tags: [redux, memory-leak, chat, cleanup]

# Dependency graph
requires:
  - phase: 19-audit-and-discovery
    provides: "CHAT-02 and CHAT-03 memory leak identification"
provides:
  - "Bounded chat message storage (MAX_MESSAGES = 500 per channel)"
  - "Chat state cleanup on session leave (clearAllMessages action)"
  - "Memory leak prevention for chat feature"
affects:
  - "22-session-screen-cleanup"
  - "23-verification-and-testing"

# Tech tracking
tech-stack:
  added: []
  patterns:
    - "Bounded Redux array storage with slice(-MAX_MESSAGES)"
    - "State cleanup dispatched before session state clear"

key-files:
  created: []
  modified:
    - "jam-ui/src/store/features/sessionChatSlice.js"
    - "jam-ui/src/components/client/JKSessionScreen.js"

key-decisions:
  - "MAX_MESSAGES = 500 per channel (sufficient for long sessions)"
  - "Clear chat state before session state for proper cleanup order"
  - "Preserve lastReadAt across sessions for UX continuity"

patterns-established:
  - "Bounded array pattern: slice(-MAX) after push/merge to cap growth"
  - "State cleanup pattern: dispatch cleanup before parent state clear"

# Metrics
duration: 2min
completed: 2026-02-08
---

# Phase 21 Plan 01: Chat State Cleanup Summary

**Bounded chat message storage (500 per channel) with clearAllMessages action to prevent unbounded memory growth**

## Performance

- **Duration:** 2 min
- **Started:** 2026-02-08T15:20:26Z
- **Completed:** 2026-02-08T15:22:39Z
- **Tasks:** 2
- **Files modified:** 2

## Accomplishments
- Added MAX_MESSAGES = 500 constant to bound chat message arrays
- Applied slice(-MAX_MESSAGES) in all 3 message-adding reducers
- Created clearAllMessages action for session leave cleanup
- Integrated clearAllMessages dispatch in both leave paths

## Task Commits

Each task was committed atomically:

1. **Task 1: Add MAX_MESSAGES limit to sessionChatSlice.js** - `f1189af67` (feat)
2. **Task 2: Add clearAllMessages action and dispatch on session leave** - `5407f1959` (feat)

## Files Created/Modified
- `jam-ui/src/store/features/sessionChatSlice.js` - Added MAX_MESSAGES constant, slice bounds in 3 reducers, clearAllMessages action
- `jam-ui/src/components/client/JKSessionScreen.js` - Import and dispatch clearAllMessages in handleLeaveSubmit and cleanup useEffect

## Decisions Made
- **MAX_MESSAGES = 500**: Sufficient for long sessions while bounding memory. Average chat rate doesn't approach this in normal use.
- **Preserve lastReadAt**: Keeps unread badge accurate across sessions for UX continuity.
- **Clear before session state**: clearAllMessages dispatched before clearSession to ensure proper cleanup order.

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered

None - pre-existing Prettier formatting errors in both files are not related to this change and were not addressed (out of scope).

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness
- Chat memory leak fixes complete (CHAT-02 and CHAT-03 addressed)
- CHAT-01 was verified OK in Phase 19 audit
- Ready for Phase 22 (Session Screen Cleanup) or Phase 23 (Verification)

---
*Phase: 21-chat-window-fixes*
*Completed: 2026-02-08*
