Add MCP server

srv/Cargo.toml

@@ -9,6 +9,9 @@ serde_json = "1.0.145"
 inkopslista-lib = { path = "../lib" }
 sqlite = "0.37.0"
 clap = { version = "4.6.6", features = ["derive", "env"] }
-axum = { version = "0.8.9", features = ["http1"] }
+axum = { version = "0.8.9", features = ["http1", "http2", "tokio"] }
 tower-http = { version = "0.7.0", features = ["fs", "trace", "compression-gzip"] }
 tokio = { version = "1.53.1", features = ["full"] }
+rmcp = { version = "3.1.2", features = ["server", "macros", "schemars", "transport-streamable-http-server", "transport-streamable-http-server-session"] }
+tracing = "0.1.44"
+tracing-subscriber = { version = "0.3.23", features = ["env-filter"] }

srv/src/main.rs

@@ -9,6 +9,10 @@ use std::net::SocketAddr;
 use std::path::PathBuf;
 use std::sync::Arc;
 use tower_http::services::ServeDir;
+use tower_http::trace::TraceLayer;
+use tracing::Level;
+
+mod mcp;
 
 /// The directory where the web files for the gui is stored.
 fn www_path() -> &'static std::path::Path {
@@ -116,6 +120,8 @@ struct Opt {
     bind: SocketAddr,
     #[clap(long, env = "DB_PATH")]
     db_path: PathBuf,
+    #[clap(long, env = "RUST_LOG", default_value = "debug")]
+    log_level: String,
     #[clap(long, env = "NUM_DAYS", default_value = "5")]
     num_days: u32,
 }
@@ -123,6 +129,11 @@ struct Opt {
 #[tokio::main]
 async fn main() {
     let opt = Opt::parse();
+
+    tracing_subscriber::fmt()
+        .with_env_filter(tracing_subscriber::EnvFilter::new(&opt.log_level))
+        .init();
+
     let db = sqlite::Connection::open_thread_safe(opt.db_path).unwrap();
     db.execute(include_str!("db/init.sql"))
         .expect("unable to initialize database");
@@ -135,8 +146,17 @@ async fn main() {
         .route("/api/favorites", get(get_favorites))
         .route("/api/favorites/{item}/category", put(put_category))
         .fallback_service(ServeDir::new(www_path()))
+        .nest_service("/mcp", mcp::service(db.clone()))
+        .layer(
+            TraceLayer::new_for_http()
+                .make_span_with(tower_http::trace::DefaultMakeSpan::new().level(Level::INFO))
+                .on_request(tower_http::trace::DefaultOnRequest::new().level(Level::INFO))
+                .on_response(tower_http::trace::DefaultOnResponse::new().level(Level::INFO)),
+        )
         .with_state(db);
 
     let listener = tokio::net::TcpListener::bind(opt.bind).await.unwrap();
+    tracing::info!("Listening on http://{}", opt.bind);
+
     axum::serve(listener, app).await.unwrap();
 }

srv/src/mcp.rs

@@ -0,0 +1,89 @@
+//! MCP routes
+
+use axum::Json;
+use axum::extract::{Path, State};
+use inkopslista_lib::ItemData;
+use rmcp::handler::server::wrapper::Parameters;
+use rmcp::transport::streamable_http_server::session::local::LocalSessionManager;
+use rmcp::transport::streamable_http_server::tower::{
+    StreamableHttpServerConfig, StreamableHttpService,
+};
+use rmcp::{schemars, tool, tool_router};
+use serde::Deserialize;
+use sqlite::ConnectionThreadSafe;
+use std::fmt::Write;
+use std::sync::Arc;
+
+#[derive(Debug, Deserialize, schemars::JsonSchema)]
+struct PutParams {
+    /// The name of the shopping-list item,
+    item: String,
+    /// The number of items to buy.
+    #[serde(default = "default_amount")]
+    amount: i64,
+    /// Whether the item has been checked off.
+    #[serde(default)]
+    checked: bool,
+}
+
+fn default_amount() -> i64 {
+    1
+}
+
+#[derive(Clone)]
+pub struct McpServer {
+    db: Arc<ConnectionThreadSafe>,
+}
+
+#[tool_router(server_handler)]
+impl McpServer {
+    #[tool(description = "Read the entire shopping list")]
+    async fn list(&self) -> String {
+        // TODO: don't call the HTTP request handlers. Split the DB stuff out instead.
+        let db = State(self.db.clone());
+        let items = crate::get_list(db).await.0;
+        let mut out = String::new();
+        for item in items {
+            _ = writeln!(
+                &mut out,
+                "- [{checked}] {n}x {name}",
+                checked = if item.data.checked { "x" } else { " " },
+                n = item.data.amount,
+                name = item.name,
+            );
+        }
+        out
+    }
+
+    #[tool(description = "Put an item onto the shopping list.")]
+    async fn put(&self, Parameters(params): Parameters<PutParams>) -> String {
+        // TODO: don't call the HTTP request handlers. Split the DB stuff out instead.
+        let db = State(self.db.clone());
+        let data = ItemData {
+            amount: params.amount,
+            checked: params.checked,
+        };
+        crate::put_list(db, Path(params.item), Json(data)).await;
+        "Ok".to_string()
+    }
+}
+
+/// Create an MCP service that can be plugged into axum
+pub fn service(
+    db: Arc<ConnectionThreadSafe>,
+) -> StreamableHttpService<McpServer, LocalSessionManager> {
+    // TODO: tower_http::auth::add_authorization
+    let config = StreamableHttpServerConfig::default()
+        .with_legacy_session_mode(true)
+        .with_json_response(false)
+        .disable_allowed_hosts()
+        .disable_allowed_origins();
+
+    let server = McpServer { db };
+
+    StreamableHttpService::new(
+        move || Ok(server.clone()),
+        LocalSessionManager::default().into(),
+        config,
+    )
+}