# Check Ecs > Check if code follows ECS architecture rules defined in CLAUDE.md. Use when writing or reviewing systems, components, resources, or any ECS-related code. Use when this capability is needed. - Skill: `tomevault-io/check-ecs` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/check-ecs` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/check-ecs/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/check-ecs --- # ECS Architecture Compliance Check Check the specified files or recent changes against project ECS rules. this skill is called as ``` /check-ecs ``` Or with file name as arguments ``` /check-ecs file_name ``` MUST use ecs-architecture-checker agent to explore. ## Target If `$ARGUMENTS` is provided, check those files. Otherwise, check recently modified `.rs` files. ## ECS Rules to Verify ### 1. Component Rules (`ecs/component/`) - [ ] Components are **data-only structs** — no impl blocks with logic - [ ] No `fn` methods that perform computation or mutation - [ ] Derive macros only (Debug, Clone, Default, etc.) - [ ] Located in `src/ecs/component/` **Violation example:** ```rust // BAD: Component with logic impl MyComponent { pub fn calculate_something(&self) -> f32 { ... } } ``` ### 2. System Rules (`ecs/systems/`) - [ ] All behavior implemented as **free functions** - [ ] Function naming: `_` (e.g., `camera_rotate`, `animation_update`) - [ ] Takes World/Components/Resources as parameters - [ ] Located in `src/ecs/systems/` **Violation example:** ```rust // BAD: Logic in component file // src/ecs/component/camera.rs impl Camera { pub fn rotate(&mut self, delta: Vector2) { ... } } // GOOD: Logic in system file // src/ecs/systems/camera_systems.rs pub fn camera_rotate(camera: &mut Camera, delta: Vector2) { ... } ``` ### 3. Resource Rules (`ecs/resource/`) - [ ] Resources are **global dynamic state** that changes per frame - [ ] Static configuration should NOT be a resource - [ ] Located in `src/ecs/resource/` ### 4. mod.rs Rules - [ ] `mod.rs` files contain **ONLY module declarations and re-exports** - [ ] No struct/enum definitions in mod.rs - [ ] No function implementations in mod.rs **Violation example:** ```rust // BAD: Definition in mod.rs // src/ecs/component/mod.rs pub struct MyComponent { ... } // GOOD: Only re-exports // src/ecs/component/mod.rs mod my_component; pub use my_component::MyComponent; ``` ### 5. Bones are NOT Entities - [ ] Bones are data within `Skeleton.bones: Vec` - [ ] Bones identified by `BoneId` (u32 index), not `Entity` - [ ] Constraints reference bones via `BoneId` ### 6. EntityBuilder Pattern - [ ] Use existing `EntityBuilder` for entity construction - [ ] No manual component insertion sequences - [ ] Located in `src/ecs/world.rs` ### 7. Layer Boundary Rules ECS business logic MUST live inside `src/ecs/systems/`. Code outside `src/ecs/` (especially `src/platform/`, `src/app/`) must NOT contain ECS domain logic. **Allowed in platform layer** (`src/platform/`): - Reading resources for UI display (`resource::()`, `get_resource::()`) - Sending events to `UIEventQueue` (`ui_events.send(...)`) - Calling a single ECS dispatch entry point (e.g., `run_event_dispatch_phase(...)`) - Platform-specific I/O (file dialogs via `rfd`, window management, imgui frame orchestration) - Handling `DeferredAction` that requires `App`/`GUIData` (model loading, screenshots) **NOT allowed in platform layer**: - Directly calling multiple ECS system functions to process events - Match-dispatching `UIEvent` variants to mutate `World`/`AssetStorage` - Implementing event handler logic inline (e.g., `process_*_events_inline`) - Accessing `resource_mut::()` or `get_component_mut::()` for business logic **Detection patterns** (search in files outside `src/ecs/`): ```rust // Suspicious: multiple resource_mut calls with business logic world.resource_mut::(); world.resource_mut::(); world.get_component_mut::(entity); // Suspicious: match on UIEvent with mutation logic match event { UIEvent::TimelinePlay => { /* logic here */ } UIEvent::Undo => { /* logic here */ } } ``` **Violation example:** ```rust // BAD: ECS logic in platform layer // src/platform/events.rs fn process_timeline_events(events: &[UIEvent], app: &mut App) { let mut timeline = app.data.ecs_world.resource_mut::(); let mut clips = app.data.ecs_world.resource_mut::(); timeline_process_events(events, &mut timeline, &mut clips); } // GOOD: Platform calls single ECS entry point // src/platform/events.rs let (platform_events, deferred) = run_event_dispatch_phase( &mut app.data.ecs_world, &mut app.data.ecs_assets, model_bounds, ); // GOOD: ECS logic in ECS layer // src/ecs/systems/phases/event_dispatch_phase.rs fn dispatch_timeline_events(events: &[UIEvent], world: &mut World) { ... } ``` **Scope**: This rule applies to ALL `.rs` files outside `src/ecs/`, not just recently modified ones. When running `/check-ecs` without arguments, also scan `src/platform/` and `src/app/` for layer violations. ## Check Process 1. Read the target files 2. For each file, verify against applicable rules 3. **If no arguments given**: also scan `src/platform/*.rs` and `src/app/*.rs` for Rule 7 (layer boundary) violations 4. Report violations with file path and line number 5. Suggest corrections ## Output Format ``` ## ECS Check Results ### ✅ Compliant - file.rs: Components are data-only ### ❌ Violations - src/ecs/component/foo.rs:45 - Component has logic method `calculate()` Suggestion: Move to `src/ecs/systems/foo_systems.rs` - src/ecs/component/mod.rs:12 - Struct definition in mod.rs Suggestion: Move to separate file and re-export ``` --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/kodai731) — claim your Tome and manage your conversions.