ci: add cargo fmt check to CI

.github/workflows/preview.yml

@@ -15,6 +15,12 @@ jobs:
     steps:
     - uses: actions/checkout@v4
 
+    - name: Check formatting
+      run: cargo fmt -- --check
+
+    - name: Lint
+      run: cargo clippy -- -D warnings
+
     - name: Run tests
       run: cargo test --verbose
 

AGENTS.md

@@ -42,8 +42,16 @@ cargo test get_empty_array
 cargo test get_not_empty_array
 ```
 
-### Git commits
-Always run cargo fmt before commiting changes
+### Pre-commit checklist
+Always run these before committing:
+```bash
+cargo fmt            # Format code
+cargo clippy -- -D warnings  # Lint (must pass with zero warnings)
+cargo test           # Run tests
+```
+
+### Rust version
+The project pins its Rust version in `rust-toolchain.toml`. Rustup handles this automatically — no manual version management needed. The toolchain file also ensures `rustfmt` and `clippy` components are installed.
 
 ## Code Structure
 

rust-toolchain.toml

@@ -1,2 +1,3 @@
 [toolchain]
 channel = "1.93.0"
+components = ["rustfmt", "clippy"]

src/rest/v4/activity.rs

@@ -10,9 +10,12 @@ use actix_web::web::Query;
 use regex::Regex;
 use serde::Deserialize;
 use serde::Serialize;
+use std::sync::LazyLock;
 use time::Duration;
 use time::OffsetDateTime;
 
+static TIP_RE: LazyLock<Regex> = LazyLock::new(|| Regex::new(r"(lightning:[^)]+)").unwrap());
+
 const EVENT_TYPE_CREATE: &str = "place_added";
 const EVENT_TYPE_UPDATE: &str = "place_updated";
 const EVENT_TYPE_DELETE: &str = "place_deleted";
@@ -83,8 +86,7 @@ pub async fn get(
 
         let element_name = element.name(None);
 
-        let re = Regex::new(r"(lightning:[^)]+)").unwrap();
-        let user_tip = re
+        let user_tip = TIP_RE
             .captures(&osm_user.osm_data.description)
             .map(|c| c[1].to_string());