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+---
+name: vespera-api-development
+description: Guide for developing fully automated OpenAPI/Axum APIs using the Vespera framework.
+---
+
+# Vespera API Development
+
+Vespera is a fully automated OpenAPI engine for Axum with zero-config route and schema discovery.
+It allows you to write Axum APIs and automatically generate OpenAPI 3.1 specifications.
+
+## Instructions
+
+### 1. Project Setup
+Add `vespera` to your dependencies:
+```toml
+[dependencies]
+vespera = "0.1.0"
+axum = "0.8"
+tokio = { version = "1", features = ["full"] }
+serde = { version = "1", features = ["derive"] }
+```
+
+### 2. Main Application
+Use the `vespera!` macro in `main.rs` to initialize the app. This macro automatically scans your routes.
+
+```rust
+use vespera::vespera;
+
+#[tokio::main]
+async fn main() {
+    // Basic initialization
+    let app = vespera!(
+        openapi = "openapi.json", // Optional: Generate OpenAPI spec
+        title = "My API",         // Optional: API Title
+        version = "1.0.0",        // Optional: API Version
+        docs_url = "/docs"        // Optional: Serve Swagger UI
+    );
+
+    let listener = tokio::net::TcpListener::bind("0.0.0.0:3000").await.unwrap();
+    axum::serve(listener, app).await.unwrap();
+}
+```
+
+### 3. Route Handlers
+Define routes in modules (e.g., `src/routes/`). Use the `#[vespera::route]` attribute.
+
+```rust
+use axum::{Json, Path, State};
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize)]
+pub struct User {
+    pub id: u32,
+    pub name: String,
+}
+
+// GET /users/{id}
+#[vespera::route(path = "/{id}")] // Defaults to GET if not specified
+pub async fn get_user(Path(id): Path<u32>) -> Json<User> {
+    Json(User { id, name: "Alice".into() })
+}
+
+// POST /users
+#[vespera::route(post)]
+pub async fn create_user(Json(user): Json<User>) -> Json<User> {
+    Json(user)
+}
+```
+
+### 5. Error Handling
+Vespera supports `Result<T, E>` return types. It automatically documents both the success capability (200 OK) and the error responses in the OpenAPI spec.
+
+```rust
+use axum::http::StatusCode;
+
+#[derive(Serialize, Deserialize, Schema)]
+pub struct ErrorResponse {
+    pub message: String,
+}
+
+// Result<Json<Success>, Json<Error>>
+#[vespera::route(get, path = "/may-fail")]
+pub async fn may_fail() -> Result<Json<User>, Json<ErrorResponse>> {
+    Err(Json(ErrorResponse { message: "Something went wrong".to_string() }))
+}
+
+// Result<Json<Success>, (StatusCode, Json<Error>)>
+#[vespera::route(get, path = "/not-found")]
+pub async fn not_found_example() -> Result<Json<User>, (StatusCode, Json<ErrorResponse>)> {
+    Err((
+        StatusCode::NOT_FOUND,
+        Json(ErrorResponse { message: "User not found".to_string() })
+    ))
+}
+```
+
+### 4. File Structure
+The file structure in `src/routes` maps to URL paths:
+- `src/routes/users.rs` -> `/users`
+- `src/routes/admin/stats.rs` -> `/admin/stats`
+
+## Guidelines
+- Always use `vespera!` macro instead of manually building `Router::new()`.
+- Use `#[vespera::route]` for all handlers to ensure they are picked up by the OpenAPI generator.
+- `dir` parameter in `vespera!` defaults to `"routes"`.
+- Handlers and schemas are automatically imported.