feat(xy): reload handler with diff

Implements the `reload` JSON-RPC method: diffs the on-disk config dir
against the in-memory registry and reconciles — stops removed servers,
restarts changed servers (shutdown-then-respawn), and starts new ones.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

crates/xy/src/cli/mod.rs

@@ -1,10 +1,24 @@
 use crate::paths::Paths;
-use anyhow::{bail, Result};
+use anyhow::{Result, bail};
 
-pub async fn list(_p: Paths) -> Result<i32> { bail!("not implemented") }
-pub async fn status(_p: Paths, _name: String) -> Result<i32> { bail!("not implemented") }
-pub async fn start(_p: Paths, _all: bool, _name: Option<String>) -> Result<i32> { bail!("not implemented") }
-pub async fn stop(_p: Paths, _all: bool, _name: Option<String>) -> Result<i32> { bail!("not implemented") }
-pub async fn restart(_p: Paths, _all: bool, _name: Option<String>) -> Result<i32> { bail!("not implemented") }
-pub async fn reload(_p: Paths) -> Result<i32> { bail!("not implemented") }
-pub async fn logs(_p: Paths, _name: String, _tail: Option<u32>, _follow: bool) -> Result<i32> { bail!("not implemented") }
+pub async fn list(_p: Paths) -> Result<i32> {
+    bail!("not implemented")
+}
+pub async fn status(_p: Paths, _name: String) -> Result<i32> {
+    bail!("not implemented")
+}
+pub async fn start(_p: Paths, _all: bool, _name: Option<String>) -> Result<i32> {
+    bail!("not implemented")
+}
+pub async fn stop(_p: Paths, _all: bool, _name: Option<String>) -> Result<i32> {
+    bail!("not implemented")
+}
+pub async fn restart(_p: Paths, _all: bool, _name: Option<String>) -> Result<i32> {
+    bail!("not implemented")
+}
+pub async fn reload(_p: Paths) -> Result<i32> {
+    bail!("not implemented")
+}
+pub async fn logs(_p: Paths, _name: String, _tail: Option<u32>, _follow: bool) -> Result<i32> {
+    bail!("not implemented")
+}

crates/xy/src/daemon/handlers.rs

@@ -65,7 +65,10 @@ async fn handle_request(req: Request, reg: &Registry) -> Response {
         methods::START => dispatch_lifecycle(id, params, reg, Op::Start).await,
         methods::STOP => dispatch_lifecycle(id, params, reg, Op::Stop).await,
         methods::RESTART => dispatch_lifecycle(id, params, reg, Op::Restart).await,
-        methods::RELOAD => err_response(id, -32601, "reload not yet implemented".into()),
+        methods::RELOAD => match reload(reg).await {
+            Ok(v) => ok_response(id, serde_json::to_value(v).unwrap()),
+            Err(e) => err_response(id, e.code, e.message),
+        },
         methods::LOGS => err_response(id, -32601, "logs not yet implemented".into()),
         methods::LOGS_CANCEL => err_response(id, -32601, "logs_cancel not yet implemented".into()),
         other => err_response(id, -32601, format!("unknown method `{other}`")),
@@ -246,3 +249,115 @@ async fn dispatch_lifecycle(
         }
     }
 }
+
+use xy_protocol::rpc::ReloadResult;
+
+async fn reload(reg: &Registry) -> Result<ReloadResult, ApiError> {
+    let paths = crate::daemon::PATHS.get().ok_or_else(|| {
+        ApiError::rpc(RpcErrorCode::ConfigInvalid, "daemon paths not initialized")
+    })?;
+
+    let new_configs = xy_protocol::kdl_parse::load_all_configs(&paths.config_dir)
+        .map_err(|err| ApiError::rpc(RpcErrorCode::ConfigInvalid, err.to_string()))?;
+
+    use std::collections::HashMap;
+
+    let new_by_name: HashMap<String, xy_protocol::ServerConfig> = new_configs
+        .into_iter()
+        .map(|c| (c.name.clone(), c))
+        .collect();
+
+    let existing_names: Vec<String> = reg.names().await;
+
+    let mut added = Vec::new();
+    let mut removed = Vec::new();
+    let mut changed = Vec::new();
+    let mut unchanged = Vec::new();
+
+    for name in &existing_names {
+        if !new_by_name.contains_key(name) {
+            if let Some(entry) = reg.remove(name).await {
+                let (tx, rx) = oneshot::channel();
+
+                let _ = entry
+                    .handle
+                    .tx
+                    .send(SupervisorCmd::Shutdown { ack: tx })
+                    .await;
+
+                let _ = rx.await;
+
+                removed.push(name.clone());
+            }
+        }
+    }
+
+    for (name, cfg) in new_by_name {
+        let new_hash = crate::daemon::config_hash(&cfg);
+
+        match reg.get(&name).await {
+            None => {
+                let handle = crate::daemon::spawn_supervisor(paths, cfg)
+                    .map_err(|err| ApiError::rpc(RpcErrorCode::SpawnFailed, err.to_string()))?;
+
+                reg.insert(
+                    name.clone(),
+                    crate::daemon::registry::Entry {
+                        handle: handle.clone(),
+                        config_hash: new_hash,
+                    },
+                )
+                .await;
+
+                let (tx, rx) = oneshot::channel();
+
+                let _ = handle.tx.send(SupervisorCmd::Start { ack: tx }).await;
+
+                let _ = rx.await;
+
+                added.push(name);
+            }
+            Some(entry) if entry.config_hash != new_hash => {
+                let (tx, rx) = oneshot::channel();
+
+                let _ = entry
+                    .handle
+                    .tx
+                    .send(SupervisorCmd::Shutdown { ack: tx })
+                    .await;
+
+                let _ = rx.await;
+
+                reg.remove(&name).await;
+
+                let handle = crate::daemon::spawn_supervisor(paths, cfg)
+                    .map_err(|err| ApiError::rpc(RpcErrorCode::SpawnFailed, err.to_string()))?;
+
+                reg.insert(
+                    name.clone(),
+                    crate::daemon::registry::Entry {
+                        handle: handle.clone(),
+                        config_hash: new_hash,
+                    },
+                )
+                .await;
+
+                let (tx, rx) = oneshot::channel();
+
+                let _ = handle.tx.send(SupervisorCmd::Start { ack: tx }).await;
+
+                let _ = rx.await;
+
+                changed.push(name);
+            }
+            Some(_) => unchanged.push(name),
+        }
+    }
+
+    Ok(ReloadResult {
+        added,
+        removed,
+        changed,
+        unchanged,
+    })
+}

crates/xy/src/daemon/registry.rs

@@ -15,7 +15,9 @@ pub struct Registry {
 }
 
 impl Registry {
-    pub fn new() -> Self { Self::default() }
+    pub fn new() -> Self {
+        Self::default()
+    }
     pub async fn insert(&self, name: String, entry: Entry) {
         self.inner.write().await.insert(name, entry);
     }
@@ -28,7 +30,8 @@ impl Registry {
     pub async fn names(&self) -> Vec<String> {
         let g = self.inner.read().await;
         let mut v: Vec<String> = g.keys().cloned().collect();
-        v.sort(); v
+        v.sort();
+        v
     }
     pub async fn snapshot(&self) -> Vec<(String, Entry)> {
         let g = self.inner.read().await;

crates/xy/src/main.rs

@@ -22,41 +22,54 @@ enum Cmd {
     Status { name: String },
     /// Start a server (or all configured servers with --all).
     Start {
-        #[arg(long, conflicts_with = "name")] all: bool,
-        #[arg(required_unless_present = "all")] name: Option<String>,
+        #[arg(long, conflicts_with = "name")]
+        all: bool,
+        #[arg(required_unless_present = "all")]
+        name: Option<String>,
     },
     /// Stop a server (or --all).
     Stop {
-        #[arg(long, conflicts_with = "name")] all: bool,
-        #[arg(required_unless_present = "all")] name: Option<String>,
+        #[arg(long, conflicts_with = "name")]
+        all: bool,
+        #[arg(required_unless_present = "all")]
+        name: Option<String>,
     },
     /// Restart a server (or --all).
     Restart {
-        #[arg(long, conflicts_with = "name")] all: bool,
-        #[arg(required_unless_present = "all")] name: Option<String>,
+        #[arg(long, conflicts_with = "name")]
+        all: bool,
+        #[arg(required_unless_present = "all")]
+        name: Option<String>,
     },
     /// Re-read config dir and reconcile running servers.
     Reload,
     /// Stream a server's log.
     Logs {
         name: String,
-        #[arg(long)] tail: Option<u32>,
-        #[arg(short = 'f', long)] follow: bool,
+        #[arg(long)]
+        tail: Option<u32>,
+        #[arg(short = 'f', long)]
+        follow: bool,
     },
 }
 
 #[tokio::main]
 async fn main() -> std::process::ExitCode {
     tracing_subscriber::fmt()
-        .with_env_filter(tracing_subscriber::EnvFilter::try_from_default_env()
-            .unwrap_or_else(|_| tracing_subscriber::EnvFilter::new("info")))
+        .with_env_filter(
+            tracing_subscriber::EnvFilter::try_from_default_env()
+                .unwrap_or_else(|_| tracing_subscriber::EnvFilter::new("info")),
+        )
         .with_writer(std::io::stderr)
         .init();
 
     let cli = Cli::parse();
     let paths = match paths::Paths::resolve() {
         Ok(p) => p,
-        Err(e) => { eprintln!("xy: failed to resolve XDG paths: {e}"); return std::process::ExitCode::from(3); }
+        Err(e) => {
+            eprintln!("xy: failed to resolve XDG paths: {e}");
+            return std::process::ExitCode::from(3);
+        }
     };
 
     let result: anyhow::Result<i32> = match cli.cmd {
@@ -72,6 +85,9 @@ async fn main() -> std::process::ExitCode {
 
     match result {
         Ok(code) => std::process::ExitCode::from(code as u8),
-        Err(e) => { eprintln!("xy: {e:#}"); std::process::ExitCode::from(1) }
+        Err(e) => {
+            eprintln!("xy: {e:#}");
+            std::process::ExitCode::from(1)
+        }
     }
 }

crates/xy/src/paths.rs

@@ -20,7 +20,13 @@ impl Paths {
             .map(|p| PathBuf::from(p).join("xy.sock"))
             .unwrap_or_else(|| state_dir.join("xy.sock"));
         let pidfile = state_dir.join("xy.pid");
-        Ok(Self { config_dir, state_dir, log_dir, socket, pidfile })
+        Ok(Self {
+            config_dir,
+            state_dir,
+            log_dir,
+            socket,
+            pidfile,
+        })
     }
 
     pub fn ensure_dirs(&self) -> std::io::Result<()> {

crates/xy/src/pidfile.rs

@@ -12,14 +12,22 @@ pub struct PidFile {
 impl PidFile {
     pub fn acquire(path: &Path) -> std::io::Result<Self> {
         let mut f = OpenOptions::new()
-            .write(true).create_new(true).mode(0o600).open(path)?;
+            .write(true)
+            .create_new(true)
+            .mode(0o600)
+            .open(path)?;
         writeln!(f, "{}", std::process::id())?;
-        Ok(Self { path: path.to_path_buf(), _file: f })
+        Ok(Self {
+            path: path.to_path_buf(),
+            _file: f,
+        })
     }
 }
 
 impl Drop for PidFile {
-    fn drop(&mut self) { let _ = std::fs::remove_file(&self.path); }
+    fn drop(&mut self) {
+        let _ = std::fs::remove_file(&self.path);
+    }
 }
 
 #[cfg(test)]
@@ -40,7 +48,10 @@ mod tests {
     fn drop_removes_file() {
         let dir = tempdir().unwrap();
         let p = dir.path().join("x.pid");
-        { let _g = PidFile::acquire(&p).unwrap(); assert!(p.exists()); }
+        {
+            let _g = PidFile::acquire(&p).unwrap();
+            assert!(p.exists());
+        }
         assert!(!p.exists());
     }
 }