refactoring app name to spacetris and new icon

cooperate_mode_plan.md

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+# Spacetris — COOPERATE Mode (Two-Player Co-Op)  
+## VS Code Copilot AI Agent Prompt
+
+> Implement a new **COOPERATE** play mode for Spacetris.  
+> This is a **two-player cooperative mode** with a shared board and synchronized line clears.
+
+---
+
+## 1. Mode Overview
+
+### Mode Name
+- **COOPERATE**
+
+### Core Concept
+- Two players play **together**, not versus.
+- One shared game board with **double width**.
+- Each player is responsible for **their own half** of the board.
+- A line clears **only when BOTH halves of the same row are full**.
+
+---
+
+## 2. Grid Layout
+
+- Grid width: **20 columns**
+- Grid height: **standard height** (same as Endless/Challenge)
+- Column ownership:
+  - Player 1 → columns `0–9` (left half)
+  - Player 2 → columns `10–19` (right half)
+
+### Visual Requirements
+- Draw a **vertical divider line** between columns 9 and 10.
+- Divider should be subtle but always visible.
+
+---
+
+## 3. Line Clear Rule (Critical)
+
+A row clears **only if**:
+- Player 1 half of the row is completely filled
+- AND Player 2 half of the row is completely filled
+
+If only one side is filled:
+- The row **does NOT clear**
+- Provide visual feedback:
+  - Glow or pulse on the completed half
+  - Optional hint on the incomplete half
+
+---
+
+## 4. Player Mechanics
+
+### Piece Streams
+- Each player has their **own active piece**
+- Each player has their **own NEXT queue**
+- Both queues use the **same RNG seed** for fairness
+
+### Controls
+- Player 1 controls only the left half
+- Player 2 controls only the right half
+- Players cannot move or rotate pieces into the other player’s half
+
+---
+
+## 5. Gravity & Timing
+
+- Gravity applies globally (same speed for both)
+- Lock delay is handled **per player**
+- One player locking does NOT block the other player
+
+---
+
+## 6. Failure Conditions
+
+Recommended:
+- Game over occurs only when **both players top out**
+
+Alternative (optional):
+- If either player tops out → shared loss
+
+---
+
+## 7. Scoring System
+
+- Score is **shared**
+- Line clears grant:
+  - Base score
+  - Cooperative bonus if both halves complete simultaneously
+  - Combo bonus for consecutive cooperative clears
+
+No competitive scoring between players.
+
+---
+
+## 8. UI / HUD Requirements
+
+- Two NEXT panels (one per player)
+- Shared score display
+- Shared level display
+- Visual feedback for:
+  - Half-filled rows
+  - Successful cooperative clears
+
+Optional:
+- SYNC meter for advanced cooperative mechanics (future)
+
+---
+
+## 9. Data Model Suggestions
+
+```cpp
+enum class PlayerSide {
+    Left,
+    Right
+};
+
+struct PlayerState {
+    PlayerSide side;
+    ActivePiece piece;
+    bool isAlive;
+};
+
+struct Cell {
+    bool occupied;
+    PlayerSide owner;
+};
+````
+
+---
+
+## 10. Line Clear Algorithm (Guidance)
+
+When checking for full rows:
+
+1. For each row:
+
+   * Check columns `0–9` for full (Player 1)
+   * Check columns `10–19` for full (Player 2)
+2. Only if **both are full**, mark row for clearing
+3. Clear row normally and apply gravity to both halves
+4. Update shared score and combos
+
+---
+
+## 11. Constraints
+
+* COOPERATE is a separate play mode
+* Do NOT reuse versus or garbage mechanics
+* Focus on clarity, fairness, and readability
+* Keep implementation modular (easy to expand later)
+
+---
+
+## 12. Acceptance Criteria
+
+* Two players can play simultaneously on one board
+* Each player fills only their half
+* Lines clear only when both halves are filled
+* Visual feedback clearly shows cooperative dependency
+* Mode integrates cleanly into the main menu
+
+---
+
+## 13. Optional Future Hooks (Do Not Implement Now)
+
+* Assist blocks
+* Shared power-ups
+* Cross-half interactions
+* Online co-op
+
+---
+
+## Short Summary for the Agent
+
+Implement a two-player COOPERATE mode with a 20-column board split into two halves. Each player fills their half independently. A line clears only when both halves of the same row are full. Score, level, and progress are shared. Add clear visual feedback and a divider between player halves.