build.rs — Protobuf Compilation

The build script runs before the Rust compiler and is responsible for compiling all .proto files into Rust code. It does this in several steps:

1. Collect proto files Recursively scans the src-tauri/proto/ directory for .proto files. Only files that are inside a components/ subdirectory are included — this is a deliberate filter to exclude top-level or organisational proto files.

2. Patch proto files Each .proto file is copied to a temporary directory inside OUT_DIR and patched to inject package packets; as the second line. This ensures all generated types end up in a single packets Rust module, regardless of how the source .proto files are organised. The patching is idempotent — it won't inject the package line twice if it is already present.

3. Compile with prost The patched files are compiled using prost_build. A type attribute is applied globally:

rust

config.type_attribute(".", "#[derive(serde::Serialize)]");

This means every generated message struct and enum automatically derives serde::Serialize, so they can be passed directly as Tauri event payloads without any manual wrapper types.

4. protoc The protoc compiler binary is sourced from protoc-bin-vendored, so no system installation of protoc is required.

For future developers: if you add new .proto files, place them inside a components/ subdirectory under src-tauri/proto/ and they will be picked up automatically on the next build.