/godot-master

NEVER Do (Expert Anti-Patterns)

Design & Player Experience

• NEVER punish experimentation; strictly provide Undo/Reset functionality to allow risk-free hypothesis testing.
• NEVER require pixel-perfect input for logic puzzles; strictly use Grid Snapping or large, forgiving hitboxes.
• NEVER allow undetected Soft-Locks (unsolvable states); strictly notify the player or provide immediate backtracking.
• NEVER hide the rules of the world; strictly ensure visual feedback is instant and unambiguous (e.g., powered wires must glow).
• NEVER skip the Non-Verbal Tutorial phase; strictly introduce mechanics in isolation before combining them.

Grid Logic & State

• NEVER use floating-point numbers (Vector2) for grid coordinates; strictly use Vector2i to prevent precision drift.
• NEVER use _process() for grid-state or win-condition validation; strictly trigger checks only when a piece moves.
• NEVER rely on the SceneTree structure as the source of truth; strictly maintain grid data in a separate script/dictionary.
• NEVER modify a Dictionary or Array size while iterating over it; strictly use a copy or a separate queue for modifications.
• NEVER calculate heavy recursive solvers in _process(); strictly cache results or use threaded workers for solve-checks.
• NEVER ignore diagonal rules in pathfinding; strictly configure AStarGrid2D.diagonal_mode correctly.

Architecture & Performance

• NEVER ship dual undo authorities; strictly use Godot's built-in UndoRedo via puzzle_undo_manager.gd — do not also maintain a hand-rolled Command stack.
• NEVER intermingle "do" and "undo" logic in the same function; strictly maintain separation for predictable rollbacks.
• NEVER use exact floating-point equality (==); strictly use is_equal_approx() for spatial constraints.
• NEVER use load() for resetting large rooms dynamically; strictly use ResourceLoader.load_threaded_request().
• NEVER leave Tween objects unreferenced; strictly kill active tweens before starting new movement on the same object.

🛠 Expert Components (scripts/)

MANDATORY reads before implementing the matching system:

1. puzzle_undo_manager.gd — sole undo authority (UndoRedo)
2. grid_manager.gd — Vector2i grid as truth
3. puzzle_state_validator.gd — soft-lock / win checks on commit

Original Expert Patterns

• puzzle_undo_manager.gd - Godot UndoRedo wrapper for move do/undo (golden path).

Modular Components

• grid_manager.gd - Vector2i board state decoupled from SceneTree.
• grid_tween_mover.gd - Kill-before-recreate Tweens for piece moves.
• puzzle_state_validator.gd - Win / soft-lock validation after commits.
• grid_input_manager.gd - Snapped grid input.
• match_three_logic.gd - Match-3 resolve / cascade helpers.
• puzzle_pathfinder.gd - AStarGrid2D hints (diagonal_mode).
• puzzle_saver.gd - Level / snapshot serialization.
• puzzle_validator.gd - Broader solvability checks.
• puzzle_history.gd - Thin UndoRedo action helpers (complements undo manager).
• tile_animator.gd - Tile juice without owning state.
• shuffle_bag.gd - Fair random piece bags.
• perspective_overlay.gd - Perspective / overlay puzzles.
• sleepy_block.gd - Timed / sleeping block mechanic sample.

Do NOT load command_undo_redo.gd — legacy hand-rolled Command stack superseded by UndoRedo.

Core Loop

1. Observe → 2. Hypothesize → 3. Commit move → 4. Validate → 5. Undo/Reset if needed

Decision Trees

Genre → scripts

Undo authority

Skill Chain

Common Pitfalls

MANDATORY for depth beyond decision trees and script catalog: puzzle-elite-implementations.md. Do NOT Load on first-pass wiring — use bundled scripts/ first.

Architecture Overview

1. Command Pattern (Undo System)

Essential for puzzle games. Never punish testing.

## Godot-Specific Tips

*   **Tweens**: Use `create_tween()` for all grid movements. It feels much better than instant snapping.
*   **Custom Resources**: Store level data (layout, starting positions) in `.tres` files for easy editing in the Inspector.
*   **Signals**: Use signals like `state_changed` to update UI/Visuals decoupled from the logic.

---

## Reference

> Progressive disclosure: open Official Documentation links only when researching a specific API;
> load Related Skills when routing work to a peer domain — do not preload the whole lattice.

### Official Documentation
- [UndoRedo](https://docs.godotengine.org/en/stable/classes/class_undoredo.html) — Built-in action history for do/undo/redo so puzzle experimentation does not require a hand-rolled command stack.
- [AStarGrid2D](https://docs.godotengine.org/en/stable/classes/class_astargrid2d.html) — Uniform-grid pathfinding (`diagonal_mode`, `jumping_enabled`) for hints and reachability on Sokoban-style boards.
- [Tween](https://docs.godotengine.org/en/stable/classes/class_tween.html) — Interruptible `create_tween()` motion for cell-to-cell feedback while logical `Vector2i` state updates immediately.
- [Using TileMaps](https://docs.godotengine.org/en/stable/tutorials/2d/using_tilemaps.html) — TileMapLayer workflows for painting walls/targets while keeping puzzle truth in a separate grid dictionary.
- [Saving games](https://docs.godotengine.org/en/stable/tutorials/io/saving_games.html) — Persist level progress, stars, and mid-puzzle snapshots without relying on scene reload as save.
- [Using InputEvent](https://docs.godotengine.org/en/stable/tutorials/inputs/inputevent.html) — Device-agnostic click/drag/action routing for forgiving grid selection and move commits.
- [Resources](https://docs.godotengine.org/en/stable/tutorials/scripting/resources.html) — Store layouts and starting piece sets as `.tres`/`Resource` data editable in the Inspector.
- [Physics introduction](https://docs.godotengine.org/en/stable/tutorials/physics/physics_introduction.html) — RigidBody sleep, layers, and integration hooks for physics-driven puzzle pieces.
- [Idle and Physics Processing](https://docs.godotengine.org/en/stable/tutorials/scripting/idle_and_physics_processing.html) — Why win/soft-lock checks belong on move commits, not every `_process` frame.
- [Data preferences](https://docs.godotengine.org/en/stable/tutorials/best_practices/data_preferences.html) — Prefer integer grid keys (`Vector2i`) and explicit dictionaries over SceneTree-as-truth.
- [Runtime file loading and saving](https://docs.godotengine.org/en/stable/tutorials/io/runtime_file_loading_and_saving.html) — `FileAccess`/`user://` patterns for custom level JSON and editor export packs.
- [JSON](https://docs.godotengine.org/en/stable/classes/class_json.html) — Serialize compact puzzle boards when splitting `Vector2` fields for portable level files.

### Related Skills

#### Prerequisites
- [godot-input-handling](input-handling.md) — Buffered InputEvent/action maps so grid clicks and directional moves stay device-agnostic and forgiving.
- [godot-signal-architecture](signal-architecture.md) — Safe `state_changed` / `level_complete` wiring so UI and VFX stay decoupled from grid truth.
- [godot-project-foundations](project-foundations.md) — Autoload/project layout baselines before stacking undo managers, savers, and level packs.

#### Complements
- [godot-tweening](tweening.md) — Deeper Tween composition when cell moves, match clears, and resets need interruptible juice without logic races.
- [godot-save-load-systems](save-load-systems.md) — Progress ownership, versioning, and threaded loads beyond per-level JSON snapshots.
- [godot-tilemap-mastery](tilemap-mastery.md) — TileMapLayer painting, custom data, and terrain patterns that visualize walls while scripts own solvability.
- [godot-navigation-pathfinding](navigation-pathfinding.md) — Broader Navigation/A* stacks when puzzle hints outgrow a single `AStarGrid2D` region.
- [godot-2d-physics](2d-physics.md) — RigidBody sleep, layers, and queries for physics puzzles that still need deterministic settle/win checks.
- [godot-state-machine-advanced](state-machine-advanced.md) — Phase FSMs (observe → move → resolve → win) when puzzles mix animation locks with input gates.
- [godot-camera-systems](camera-systems.md) — Camera2D/3D framing and unproject helpers for perspective/world-space puzzle overlays.
- [godot-ui-containers](ui-containers.md) — Minimal undo/reset HUD layouts that stay non-intrusive during non-verbal tutorials.

#### Downstream / consumers
- [godot-monte-carlo-balancer](monte-carlo-balancer.md) — Sample solvability, move-count distributions, and soft-lock rates so level packs stay fair as mechanics combine.
- [godot-procedural-generation](procedural-generation.md) — Generate candidate boards that still pass this skill's validators, undo constraints, and win-condition contracts.
- [godot-genre-roguelike](genre-roguelike.md) — Consumes grid/undo patterns when dungeon runs embed discrete puzzle rooms or locked-door logic.

#### Master
- [godot-master](../SKILL.md) — Library router and mirrored module entry for discovering this genre skill beside sibling domains.