[Feature]: Life MMO Backend

[evanmcfarland]

Summary

• Implements polling-based multiplayer Game of Life backend
• Creates life1_backend canister with game rooms, placements, and territory tracking
• Adds frontend integration with multiplayer game modal

Changes

• NEW: life1_backend/ - Rust canister for multiplayer game state
• MODIFIED: Cargo.toml - Added life1_backend to workspace
• MODIFIED: dfx.json - Added life1_backend canister config
• MODIFIED: canister_ids.json - Added life1_backend canister ID
• NEW: openhouse_frontend/src/pages/Life.tsx - Game of Life with multiplayer support
• MODIFIED: openhouse_frontend/src/App.tsx - Added /life route

Deployed to mainnet

• Frontend: https://pezw3-laaaa-aaaal-qssoa-cai.icp0.io/life
• Life1 Backend: pijnb-7yaaa-aaaae-qgcuq-cai
• Candid UI: https://a4gq6-oaaaa-aaaab-qaa4q-cai.raw.icp0.io/?id=pijnb-7yaaa-aaaae-qgcuq-cai

Test plan

• Backend deployed and responding to greet call
• Backend can create games (create_game)
• Backend lists games (list_games)
• Frontend builds successfully
• Frontend deployed to mainnet
• Manual test: Create multiplayer game from UI
• Manual test: Join existing game from UI

🤖 Generated with Claude Code

[claude]

Code Review: Life MMO Backend

I've reviewed PR #181 and have feedback organized by priority level.

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CRITICAL ISSUES (P0 - Must Fix)

1. Missing State Persistence (Data Loss on Upgrade)

Location: life1_backend/src/lib.rs:53-56

The canister uses RefCell and HashMap for state storage, which is volatile. All game data will be lost on canister upgrades.

Required Fix: Implement stable memory persistence using ic-stable-structures. Reference dice_backend/src/lib.rs for the correct pattern with StableBTreeMap, pre_upgrade, and post_upgrade hooks.

Impact: Users will lose all game state during canister upgrades.

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2. No Authorization/Access Control

Location: life1_backend/src/lib.rs:217-233

The submit_territory_snapshot function allows any player to overwrite territory data without consensus. A malicious player could submit fraudulent territory counts to claim victory.

Required Fix: Implement consensus mechanism, hash-based verification, or server-side calculation of territory.

Impact: Game integrity is compromised - cheating is trivial.

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3. Unbounded Memory Growth

Location: life1_backend/src/lib.rs:175

The placements vector grows indefinitely with no cleanup. Long-running games will eventually hit canister memory limits.

Required Fix: Cap placements at reasonable limit, archive old placements, or implement pagination.

Impact: Canister will run out of memory and crash.

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IMPORTANT ISSUES (P1 - Should Fix)

4. No Input Validation

Missing validation for:

• Game names: No length limits - could be megabytes
• Pattern names: Unbounded strings
• Coordinates: No bounds checking against grid dimensions
• max_players: Not enforced in join_game

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5. Frontend Integration Incomplete

The frontend has a fully functional single-player Game of Life (845 lines) but no backend integration for multiplayer. Missing polling loop, place_pattern calls, and game creation UI.

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SUGGESTIONS (P2)

• Add tests (no tests currently exist)
• Performance: list_games and get_game clone all data
• Security: Add rate limiting, replay attack protection

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POSITIVE ASPECTS

1. Clean API design with well-structured Candid interface
2. Follows project conventions
3. Good documentation with comprehensive PLAN file
4. Quality frontend single-player implementation

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PRIORITY ACTIONS

Must complete before merge:

1. Implement stable memory persistence (P0 Add Claude Code GitHub Workflow #1)
2. Add territory validation/consensus (P0 [Feature]: Implement Dice Game UI #2)
3. Fix unbounded memory growth (P0 feat: Instant Dice Randomness - Eliminate 3s VRF Delay #3)
4. Add input validation (P1 Feature: Animated 3D Dice Rolling #4)

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Overall Assessment: Needs Work

This PR has a well-designed architecture but critical data persistence and security issues must be resolved before deploying to mainnet.

Consider splitting this PR:

1. Immediate merge: Single-player Life game (frontend only)
2. Follow-up PR: Multiplayer backend after addressing P0/P1 issues

cc @evanmcfarland