fix: clean up rust cache action

README.md

@@ -4,7 +4,7 @@ Reusable Gitea Actions for Rust projects.
 
 ## actions/rust-cache
 
-Composite action that installs a Rust toolchain and caches cargo/crate dependencies.
+Composite action that restores Rust build caches, installs a Rust toolchain, and saves updated cargo/rustup/target caches after the job.
 
 ### Usage
 
@@ -18,7 +18,8 @@ jobs:
       - name: Setup Rust + Cache
         uses: https://git.ericxliu.me/eric/actions-rust/.gitea/actions/rust-cache@main
         with:
-          toolchain: stable  # optional, defaults to stable
+          toolchain: stable      # optional, defaults to stable
+          cache-prefix: rust     # optional, defaults to rust
 
       - run: cargo build --release
       - run: cargo test
@@ -26,14 +27,15 @@ jobs:
 
 ### What it does
 
-1. **Cache restore** — Restores `~/.cargo/registry`, `~/.cargo/git`, `~/.rustup/toolchains`, and `target/` using Gitea's native `actions/cache`.
-2. **Rust install** — Runs `rustup` to install or verify the requested toolchain.
-3. **PATH setup** — Appends `$HOME/.cargo/bin` to `$GITHUB_PATH` so cargo/rustc are available in subsequent steps.
+1. **Cache key** — Hashes root/workspace `Cargo.toml`, `Cargo.lock`, and `rust-toolchain*` files without relying on `hashFiles()`.
+2. **Cache restore/save** — Restores `~/.cargo/registry`, `~/.cargo/git`, `~/.rustup/toolchains`, and `target/` using Gitea's native `actions/cache`. The cache action saves updated paths in its post step after later build/test steps have populated them.
+3. **Rust install** — Runs `rustup` with the minimal profile to install or verify the requested toolchain.
+4. **PATH setup** — Appends `$HOME/.cargo/bin` to `$GITHUB_PATH` so cargo/rustc are available in subsequent steps.
 
 ### Cache key format
 
 ```
-rust-linux-{hash(Cargo.lock)}{hash(Cargo.toml)}
+{cache-prefix}-{runner.os}-{runner.arch}-{toolchain}-{hash(manifests/toolchain files)}
 ```
 
 Warm builds run in ~40–60s vs ~3min for a cold build.