diff --git a/Cargo.lock b/Cargo.lock
index 43dc217..f7b1a4a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -36,6 +36,15 @@ dependencies = [
  "serde_json",
 ]
 
+[[package]]
+name = "gg-g_counter"
+version = "0.0.1"
+dependencies = [
+ "nebkor-maelstrom",
+ "rand",
+ "serde_json",
+]
+
 [[package]]
 name = "gg-uid"
 version = "0.0.1"
diff --git a/Cargo.toml b/Cargo.toml
index d331696..bb1b15b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,5 +1,5 @@
 [workspace]
-members = ["gg-echo", "gg-uid", "gg-broadcast", "nebkor-maelstrom"]
+members = ["gg-echo", "gg-uid", "gg-broadcast", "nebkor-maelstrom", "gg-g_counter"]
 resolver = "2"
 
 [workspace.package]
@@ -9,3 +9,5 @@ license-file = "LICENSE.md"
 
 [workspace.dependencies]
 serde_json = "1"
+rand = "0.8"
+
diff --git a/gg-broadcast/Cargo.toml b/gg-broadcast/Cargo.toml
index 60f714d..a713c61 100644
--- a/gg-broadcast/Cargo.toml
+++ b/gg-broadcast/Cargo.toml
@@ -8,4 +8,4 @@ license-file.workspace = true
 [dependencies]
 serde_json.workspace = true
 nebkor-maelstrom = { path = "../nebkor-maelstrom" }
-rand = "0.8.5"
+rand.workspace = true
diff --git a/gg-g_counter/Cargo.toml b/gg-g_counter/Cargo.toml
new file mode 100644
index 0000000..eb83a0d
--- /dev/null
+++ b/gg-g_counter/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "gg-g_counter"
+edition = "2021"
+version.workspace = true
+authors.workspace = true
+license-file.workspace = true
+
+[dependencies]
+serde_json.workspace = true
+nebkor-maelstrom = { path = "../nebkor-maelstrom" }
+rand.workspace = true
+
diff --git a/gg-g_counter/src/main.rs b/gg-g_counter/src/main.rs
new file mode 100644
index 0000000..cad704a
--- /dev/null
+++ b/gg-g_counter/src/main.rs
@@ -0,0 +1,78 @@
+use std::{
+    collections::{HashMap, HashSet},
+    io::BufRead,
+    sync::{mpsc::channel, Arc, Mutex},
+    thread,
+    time::Duration,
+};
+
+use nebkor_maelstrom::{mk_payload, mk_stdin, protocol::Payload, Body, Message, Node, Runner};
+use rand::Rng;
+
+fn main() {
+    let out = std::io::stdout();
+
+    let node = Counter;
+    let node = Arc::new(Mutex::new(node));
+
+    let runner = Runner::new(node, out);
+    let runner = &runner;
+
+    let (i, extra_input, rx) = mk_stdin();
+    let init = thread::spawn(move || {
+        thread::sleep(Duration::from_millis(101));
+        extra_input
+            .send(Message {
+                body: Body::from_type("kv_init"),
+                ..Default::default()
+            })
+            .unwrap();
+    });
+
+    runner.run(rx);
+    init.join().unwrap();
+    i.join().unwrap();
+}
+
+const KEY: &str = "COUNTER";
+
+#[derive(Clone, Default)]
+struct Counter;
+
+impl Node for Counter {
+    fn handle(&mut self, runner: &Runner, req: &Message) {
+        let typ = req.body.typ.as_str();
+        let frm = req.src.as_str();
+        let nid = runner.node_id();
+        let nid = nid.as_str();
+        let msg_id = req.body.msg_id;
+
+        match typ {
+            "kv_init" => {
+                let mut nodes = runner.nodes().to_vec();
+                nodes.sort_unstable();
+                if nodes[0] == nid {
+                    let payload = mk_payload(&[
+                        ("key", KEY.into()),
+                        ("from", 0i64.into()),
+                        ("to", 0i64.into()),
+                        ("create_if_not_exists", true.into()),
+                    ]);
+                    let body = Body::from_type("cas").with_payload(payload);
+                    runner.send("seq-kv", body);
+                }
+            }
+            "add" => {
+                let mut h = |msg: &Message| {
+                    let irt = msg_id;
+                    let body = Body::from_type("add_ok").with_in_reply_to(irt);
+                    runner.send(frm, body);
+                };
+            }
+            "read" => {}
+            _ => {
+                eprintln!("unknown type: {req:?}");
+            }
+        }
+    }
+}
diff --git a/nebkor-maelstrom/src/kv.rs b/nebkor-maelstrom/src/kv.rs
new file mode 100644
index 0000000..10296aa
--- /dev/null
+++ b/nebkor-maelstrom/src/kv.rs
@@ -0,0 +1,28 @@
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+
+use crate::Body;
+
+#[derive(Debug, Default, Clone)]
+pub struct Kv {
+    pub service: String,
+}
+
+impl Kv {
+    pub fn new(service: &str) -> Self {
+        Kv {
+            service: service.to_string(),
+        }
+    }
+    pub fn read(&self, key: &str) -> Body {
+        todo!()
+    }
+
+    pub fn write(&self, key: &str, val: Value, create: bool) -> Body {
+        todo!()
+    }
+
+    pub fn cas(&self, val: Value) -> Body {
+        todo!()
+    }
+}
diff --git a/nebkor-maelstrom/src/lib.rs b/nebkor-maelstrom/src/lib.rs
index f6c929a..f7df692 100644
--- a/nebkor-maelstrom/src/lib.rs
+++ b/nebkor-maelstrom/src/lib.rs
@@ -1,15 +1,23 @@
 use std::{
-    io::{Stdout, Write},
+    any::Any,
+    collections::HashMap,
+    io::{BufRead, Stdout, Write},
     sync::{
         atomic::{AtomicU64, AtomicUsize, Ordering},
+        mpsc::{channel, Receiver, Sender},
         Arc, Mutex, OnceLock,
     },
+    thread::{self, JoinHandle},
 };
 
 pub mod protocol;
-pub use protocol::{Body, Message};
+pub use protocol::{Body, Message, Payload};
+use serde_json::Value;
+
+pub mod kv;
 
 pub type DynNode = Arc<Mutex<dyn Node>>;
+pub type Handler = Box<dyn FnMut(&Message)>;
 
 pub trait Node {
     fn handle(&mut self, runner: &Runner, msg: &Message);
@@ -22,6 +30,7 @@ pub struct Runner {
     nodes: OnceLock<Vec<String>>,
     steps: AtomicUsize,
     output: Arc<Mutex<Stdout>>,
+    handlers: Arc<Mutex<HashMap<u64, Handler>>>,
 }
 
 impl Runner {
@@ -33,24 +42,42 @@ impl Runner {
             node_id: OnceLock::new(),
             steps: AtomicUsize::new(0),
             output: Arc::new(Mutex::new(output)),
+            handlers: Default::default(),
         }
     }
 
-    pub fn run(&self, input: std::sync::mpsc::Receiver<Message>) {
+    pub fn run(&self, input: Receiver<Message>) {
         for msg in input.iter() {
-            self.steps.fetch_add(1, Ordering::SeqCst);
             let typ = &msg.body.typ;
             if let "init" = typ.as_str() {
                 self.init(&msg);
                 let body = Body::from_type("init_ok");
                 self.reply(&msg, body);
             } else {
+                let irt = msg.body.in_reply_to;
+                {
+                    let mut g = self.handlers.lock().unwrap();
+                    if let Some(mut h) = g.remove(&irt) {
+                        h(&msg);
+                    }
+                }
                 let mut n = self.node.lock().unwrap();
                 n.handle(self, &msg);
             }
         }
     }
 
+    pub fn rpc(&self, dest: &str, body: Body, handler: Handler) {
+        let mut body = body;
+        let msg_id = self.next_msg_id();
+        body.msg_id = msg_id;
+        {
+            let mut g = self.handlers.lock().unwrap();
+            g.insert(msg_id, handler);
+        }
+        self.send(dest, body);
+    }
+
     pub fn node_id(&self) -> String {
         self.node_id.get().cloned().unwrap_or_default()
     }
@@ -125,3 +152,30 @@ impl Runner {
         out.flush().unwrap();
     }
 }
+
+/// Feeds lines from stdin to the MPSC Sender, so that the Receiver can be used
+/// in the Runner::run() method. Clone the Sender if you want to inject messages
+/// into the Runner. Join the handle after `run()`.
+pub fn mk_stdin() -> (JoinHandle<()>, Sender<Message>, Receiver<Message>) {
+    let stdin = std::io::stdin();
+    let (tx, rx) = channel();
+    let xtra_input = tx.clone();
+
+    let join = thread::spawn(move || {
+        let g = stdin.lock();
+        for line in g.lines().map_while(Result::ok) {
+            if let Ok(msg) = serde_json::from_str(&line) {
+                tx.send(msg).unwrap();
+            }
+        }
+    });
+
+    (join, xtra_input, rx)
+}
+
+pub fn mk_payload(payload: &[(&str, Value)]) -> Payload {
+    payload
+        .iter()
+        .map(|p| (p.0.to_string(), p.1.clone()))
+        .collect()
+}