# NPC Behavior Implementation Plan - Changes Summary

**Date**: November 9, 2025  
**Status**: All planning documents updated to v2.0 (Post-Review)

---

## Overview

All NPC behavior planning documents have been updated based on the comprehensive review in `PLAN_REVIEW_AND_RECOMMENDATIONS.md`. This document summarizes the changes applied.

---

## Critical Issues Fixed

### 1. ✅ Animation Creation Timing (CRITICAL)

**Issue**: Plan said to create animations in Phase 3, but they must be created during sprite setup.

**Fix Applied**:
- **IMPLEMENTATION_PLAN.md**: Added Phase 0 with animation prerequisites
- Moved animation creation requirement BEFORE Phase 1
- Added specific frame numbers for walk and idle animations
- Clarified animations created in `npc-sprites.js`, not later

**Files Modified**:
- `IMPLEMENTATION_PLAN.md`: Phase 0 added, animation section rewritten
- `README.md`: Phase 0 added to workflow
- `QUICK_REFERENCE.md`: Added troubleshooting for missing animations

---

### 2. ✅ Integration Point Corrected (CRITICAL)

**Issue**: Plan said to register behaviors in `game.js`, but they must be registered per-room in `rooms.js`.

**Fix Applied**:
- **IMPLEMENTATION_PLAN.md**: 
  - Removed incorrect `game.js` registration loop
  - Added `rooms.js` integration section
  - Updated `game.js` to only initialize manager (not register behaviors)
  - Added code for registering in `createNPCSpritesForRoom()`

**Files Modified**:
- `IMPLEMENTATION_PLAN.md`: Integration points section rewritten
- `README.md`: Updated integration checklist

---

### 3. ✅ RoomId Storage Added (HIGH)

**Issue**: NPCs need `roomId` property for patrol bounds, but it wasn't being stored.

**Fix Applied**:
- **IMPLEMENTATION_PLAN.md**: Added scenario initialization section
- Added code to set `npc.roomId = roomId` during room initialization
- Updated patrol behavior to use stored roomId

**Files Modified**:
- `IMPLEMENTATION_PLAN.md`: Added section 4 to Integration Points
- `README.md`: Added to Phase 0 checklist

---

### 4. ✅ Validation Added (HIGH)

**Issue**: Missing validation for sprite references, roomId, and patrol bounds.

**Fix Applied**:
- **IMPLEMENTATION_PLAN.md**: 
  - Added sprite validation in constructor
  - Added roomId validation in constructor
  - Added patrol bounds validation in parseConfig()
  
**Code Added**:
```javascript
// Sprite validation
if (!this.sprite || !this.sprite.body) {
  throw new Error(`❌ Invalid sprite provided for NPC ${npcId}`);
}

// Patrol bounds validation (auto-expand if needed)
if (!inBoundsX || !inBoundsY) {
  console.warn(`⚠️ Expanding patrol bounds...`);
  // Auto-expand logic
}
```

**Files Modified**:
- `IMPLEMENTATION_PLAN.md`: Constructor and parseConfig() updated
- `README.md`: Added validation to checklist

---

### 5. ✅ Depth Updates Explicit (HIGH)

**Issue**: Plan mentioned `updateDepth()` but didn't show when to call it.

**Fix Applied**:
- **IMPLEMENTATION_PLAN.md**: Added explicit `updateDepth()` call in update loop
- Added comment explaining it's critical for Y-sorting
- Showed full update() method implementation

**Files Modified**:
- `IMPLEMENTATION_PLAN.md`: update() method rewritten

---

### 6. ✅ Collision Configuration Clarified (MEDIUM)

**Issue**: Plan incorrectly suggested NPCs should match player collision (15x10).

**Fix Applied**:
- **IMPLEMENTATION_PLAN.md**: Added "Important Notes" section
- Documented that NPCs use 18x10 intentionally (wider for patrol)
- Explained why it's different from player (15x10)
- Added warning: "Do not match player collision"

**Files Modified**:
- `IMPLEMENTATION_PLAN.md`: Added Important Notes section
- `QUICK_REFERENCE.md`: Added Design Notes section
- `README.md`: Added to Key Design Decisions

---

### 7. ✅ Personal Space Wall Collision (MEDIUM)

**Issue**: Personal space backing had no wall detection, causing stuck NPCs.

**Fix Applied**:
- **IMPLEMENTATION_PLAN.md**: Updated `maintainPersonalSpace()` algorithm
- Changed from velocity-based to position-based movement
- Added collision detection by checking if position changed

**Code Changed**:
```javascript
// OLD: Used velocity (could push through walls)
this.sprite.body.setVelocity(moveX * moveSpeed, moveY * moveSpeed);

// NEW: Uses position with collision check
const oldX = this.sprite.x;
const oldY = this.sprite.y;
this.sprite.setPosition(this.sprite.x + backX, this.sprite.y + backY);

if (this.sprite.x === oldX && this.sprite.y === oldY) {
  // Blocked by wall - just face player
  this.facePlayer(playerPos);
}
```

**Files Modified**:
- `IMPLEMENTATION_PLAN.md`: Personal space algorithm rewritten
- `QUICK_REFERENCE.md`: Added wall collision troubleshooting

---

### 8. ✅ Animation Fallback Strategy (MEDIUM)

**Issue**: No fallback if walk animations missing.

**Fix Applied**:
- **IMPLEMENTATION_PLAN.md**: Added fallback logic to playAnimation()
- Falls back to idle animation if walk doesn't exist
- Added console warnings for missing animations

**Files Modified**:
- `IMPLEMENTATION_PLAN.md`: playAnimation() rewritten
- `QUICK_REFERENCE.md`: Added troubleshooting

---

### 9. ✅ Event Emission Added (ENHANCEMENT)

**Issue**: No events emitted when NPC behavior changes.

**Fix Applied**:
- **IMPLEMENTATION_PLAN.md**: Added event emission to setHostile()
- Emits `npc_hostile_changed` event for other systems

**Files Modified**:
- `IMPLEMENTATION_PLAN.md`: setHostile() method updated

---

## Documentation Updates

### IMPLEMENTATION_PLAN.md (v2.0)
- ✅ Added Phase 0: Pre-Implementation Prerequisites
- ✅ Renumbered phases (Phase 3 → Phase 2, etc.)
- ✅ Removed incorrect Phase 3 "Animations"
- ✅ Updated all integration points
- ✅ Added constructor validation
- ✅ Added parseConfig() validation
- ✅ Rewrote personal space algorithm
- ✅ Added animation fallback
- ✅ Added event emission
- ✅ Added Important Notes section
- ✅ Updated risk assessment with status
- ✅ Updated all code examples
- ✅ Added v2.0 status footer

### QUICK_REFERENCE.md (v2.0)
- ✅ Added troubleshooting for missing animations
- ✅ Added troubleshooting for wall collisions
- ✅ Added troubleshooting for roomId errors
- ✅ Added troubleshooting for collision issues
- ✅ Added Design Notes section (personal space philosophy)
- ✅ Added Design Notes section (collision differences)
- ✅ Updated debug mode section
- ✅ Added v2.0 status footer

### README.md (v2.0)
- ✅ Added warning to read review first
- ✅ Added Phase 0 to workflow
- ✅ Added PLAN_REVIEW_AND_RECOMMENDATIONS.md to document index
- ✅ Updated all phase numbers
- ✅ Added Phase 0 to integration checklist
- ✅ Added validation items to checklist
- ✅ Updated Known Limitations section
- ✅ Added Key Design Decision #6 (collision boxes)
- ✅ Added contributing guidelines (read review first)
- ✅ Updated file locations
- ✅ Added version history
- ✅ Added v2.0 status footer

### TECHNICAL_SPEC.md
- ⚠️ **NOT UPDATED** - Marked as needing updates in README
- Review recommended updates to this file in detail
- Should be updated before Phase 1 implementation

---

## Phase Structure Changes

### Old Phase Structure (v1.0)
1. Phase 1: Core Infrastructure
2. Phase 2: Face Player
3. **Phase 3: Animations** ← REMOVED (moved to Phase 0)
4. Phase 4: Patrol Behavior
5. Phase 5: Personal Space
6. Phase 6: Ink Integration
7. Phase 7: Hostile Behavior
8. Phase 8: Documentation & Testing

### New Phase Structure (v2.0)
0. **Phase 0: Pre-Implementation Prerequisites** ← NEW (MANDATORY)
1. Phase 1: Core Infrastructure (+ validation)
2. Phase 2: Face Player
3. Phase 3: Patrol Behavior (animations already created)
4. Phase 4: Personal Space (+ wall collision)
5. Phase 5: Ink Integration
6. Phase 6: Hostile Behavior (+ event emission)
7. Phase 7: Polish & Debug (+ fallback + depth + debug viz)
8. Phase 8: Documentation & Testing

**Key Change**: Animations MUST be created in Phase 0 before any behavior implementation.

---

## Integration Changes

### Old Integration (WRONG)
```javascript
// In game.js create() - WRONG APPROACH
for (const [npcId, npcData] of window.npcManager.npcs) {
  window.npcBehaviorManager.registerBehavior(npcId, npcData._sprite, npcData.behavior);
}
```

**Problem**: NPCs registered to manager before sprites created.

### New Integration (CORRECT)
```javascript
// In game.js create() - Only initialize manager
window.npcBehaviorManager = new NPCBehaviorManager(this, window.npcManager);

// In rooms.js createNPCSpritesForRoom() - Register per sprite
if (window.npcBehaviorManager && npc.behavior) {
  window.npcBehaviorManager.registerBehavior(npc.id, sprite, npc.behavior);
}
```

**Fix**: Behaviors registered as sprites are created, per-room.

---

## Code Examples Added

### 1. Patrol Bounds Validation
Full code added to parseConfig() for auto-expanding bounds.

### 2. Constructor Validation
Full code added for sprite and roomId validation.

### 3. Personal Space Wall Collision
Full code added for position-based backing with collision check.

### 4. Animation Fallback
Full code added for graceful degradation when animations missing.

### 5. Event Emission
Full code added for hostile state change events.

### 6. Depth Updates
Full code added showing explicit updateDepth() call in update loop.

---

## New Sections Added

### IMPLEMENTATION_PLAN.md
- Phase 0: Pre-Implementation Prerequisites (complete with frame numbers)
- Integration Points section 3: rooms.js Integration
- Integration Points section 4: Scenario Initialization - Add RoomId
- Important Notes section (collision configuration)

### QUICK_REFERENCE.md
- Troubleshooting: Walk Animations Not Playing
- Troubleshooting: NPC Backs Into Wall and Gets Stuck
- Troubleshooting: NPC Collision Box Issues
- Troubleshooting: RoomId Missing Errors
- Design Notes: Personal Space Philosophy
- Design Notes: NPC Collision vs Player Collision

### README.md
- Document Index: PLAN_REVIEW_AND_RECOMMENDATIONS.md
- Implementation Workflow: Phase 0 section
- Integration Checklist: Phase 0 subsection
- Known Limitations: Animation fallback item
- Key Design Decisions: Why are NPC collision boxes wider?
- Contributing: Read review first guideline
- Version History section

---

## Files Modified

1. ✅ `PLAN_REVIEW_AND_RECOMMENDATIONS.md` - Created (comprehensive review)
2. ✅ `IMPLEMENTATION_PLAN.md` - Updated to v2.0 (13 major changes)
3. ✅ `QUICK_REFERENCE.md` - Updated to v2.0 (7 sections added)
4. ✅ `README.md` - Updated to v2.0 (9 sections modified)
5. ⚠️ `TECHNICAL_SPEC.md` - Needs updates (marked in README)
6. ✅ `CHANGES_SUMMARY.md` - Created (this file)

---

## Action Items for Implementation

### Before Starting Phase 1:
- [ ] Read `PLAN_REVIEW_AND_RECOMMENDATIONS.md` completely
- [ ] Implement Phase 0 prerequisite #1: Modify `npc-sprites.js`
  - Add walk animations for 5 directions
  - Add idle animations for 5 directions
  - Use frame numbers from IMPLEMENTATION_PLAN.md Phase 0
- [ ] Implement Phase 0 prerequisite #2: Add roomId to NPCs
  - Modify scenario initialization in `rooms.js`
- [ ] Verify integration points are correct
- [ ] Get sign-off on corrected plans
- [ ] Update `TECHNICAL_SPEC.md` (optional, but recommended)

### During Implementation:
- Follow updated IMPLEMENTATION_PLAN.md v2.0 phase structure
- Use validation patterns from updated constructor
- Use collision detection for personal space
- Add event emission for state changes
- Add animation fallback strategy
- Call updateDepth() explicitly in update loop

---

## Success Metrics

### Before Review
- **Estimated Success Rate**: 25% (critical issues would cause failure)

### After Review
- **Estimated Success Rate**: 95% (with Phase 0 completed)

**Key Improvements**:
1. Animation timing fixed → eliminates silent failures
2. Integration point fixed → behaviors actually register
3. Validation added → catches configuration errors early
4. Wall collision added → prevents stuck NPCs
5. Documentation clarified → reduces confusion

---

## Summary

All planning documents have been updated to address the critical issues identified in the review. The implementation is now **ready to proceed** once Phase 0 prerequisites are completed.

**Key Takeaway**: Phase 0 is **mandatory** - do not start Phase 1 without completing animation creation and roomId initialization.

---

**Document Created**: November 9, 2025  
**Review Applied**: PLAN_REVIEW_AND_RECOMMENDATIONS.md  
**Documents Updated**: 4 (IMPLEMENTATION_PLAN, QUICK_REFERENCE, README, this summary)  
**Critical Issues Fixed**: 9  
**Ready for Implementation**: ✅ (after Phase 0)
