epix_engine

Audit and implement Bevy API parity for an epix_engine module. Use when syncing a C++ module with its Bevy counterpart; when checking which Bevy APIs are missing, different, or intentionally skipped; when implementing a Rust-to-C++ API translation. Produces a documentation/tmp/BEVY_MATCH_STATUS.md tracker and implements missing APIs in the correct module files.

Interactively debug source code — set breakpoints, step through execution line by line, inspect live variable state, evaluate expressions against the running program, and navigate the call stack to trace root causes. Use when a program crashes, raises unexpected exceptions, produces wrong output, when you need to understand how execution reached a certain state, or when print-statement debugging isn't revealing enough.

Use when writing or modifying code with our custom WebGPU C++ wrapper (libs/webgpu-wrapper/). Covers SmallVec struct array fields, callback lifetime and ref-count rules, and enum value style. Apply whenever creating or modifying wgpu:: handles, descriptors, callbacks, feature/format lists, or any wgpu:: API calls.

Write, register, and debug Slang shaders in epix_engine. Use when authoring .slang shader files, wiring them into the ShaderCache/ShaderLoader pipeline, adding preprocessor defs variants, resolving import errors, or diagnosing Slang compile failures. Covers entry points, module declarations, VFS import rules, and C++ integration API.

Write or update documentation for an epix_engine module. Use when adding docs for a new or existing module; when auditing a module for missing docs; when documenting unimplemented or partially implemented features. Produces a documentation/<module>/ folder with separate files: quick.md, one .md per feature, and todo.md.

Explore and understand engine-internal epix_engine modules before writing code that depends on them. Use when looking up the API of an engine module (epix_core, epix_render, epix_assets, epix_shader, etc.); when unsure how to use an engine system; when finding the right exported types or functions. Follows public-interface-first order: docs → module interfaces → examples → implementation.

Learn and use a third-party C++ library by reading its public interface and documentation. Use when integrating, using, or debugging a third-party dependency; when looking up API usage of a library; when a new library needs to be explored before writing code that depends on it. Do NOT read library implementation (.cpp) files unless a compilation error explicitly requires it.