The review confirmed the plan's viability and strengths. I also identified some minor areas for clarification and key challenges. I didn't find an existing Vulkan rendering backend in the core raylib source, which makes this plan relevant.

This outlines the necessary modifications across the build system (CMake), graphics abstraction layer (rlgl), core library (rcore), platform-specific code, and shader handling to integrate Vulkan support into raylib. The strategy emphasizes conditional compilation based on a `GRAPHICS_API_VULKAN` flag and aims to mirror the existing OpenGL backend abstraction.

This commit introduces a new file, vulkan-upgrade-plan, which outlines a comprehensive strategy for integrating Vulkan as a compile-time graphics backend option for raylib.

The plan details the necessary changes across the codebase, including:
- Creation of a Vulkan abstraction layer (rlvk).
- Modifications to the core library (rcore.c) for conditional graphics backend selection.
- Updates to the platform layer (e.g., rcore_desktop_glfw.c) for Vulkan surface creation.
- Integration into the CMake build system.
- Shader management for SPIR-V.

This document serves as a roadmap for the potential Vulkan implementation and does not modify any existing code other than adding this plan file.