per-source polling, initial client state, webhook, preview, client tracking

- per-source poll intervals: spawn task per source with own interval,
  manager re-checks sources every 30s for add/remove
- initial screen update on TCP connect: send layout + widget states
- client tracking: ClientRegistry port, GET /api/clients, dashboard list
- webhook adapter: POST /api/webhook/{source_id} feeds data into projection
- widget preview: GET /api/widgets/{id}/preview returns current state
- serve SPA from Axum: ServeDir + index.html fallback via KFRAME_SPA_DIR
- layout builder delete confirmation with AlertDialog
- form validation: required fields disable save button
- guide page at /guide
- fix architecture: ClientDto to api-types, ClientRegistry + WidgetStateReader
  ports in domain, DataProjection has internal Mutex, no adapter cross-deps
- ESP32: full screen clear on layout change (stale pixel fix)

crates/adapters/tcp-server/src/server.rs

@@ -1,15 +1,27 @@
-use crate::broadcaster::TcpBroadcaster;
+use crate::client_tracker::ClientTracker;
 use crate::error::TcpServerError;
+use domain::{ConfigRepository, WidgetStateReader};
+use protocol::{ServerMessage, WidgetDescriptor, WireDisplayHint, WireLayoutNode, encode};
 use std::sync::Arc;
 use tokio::io::AsyncWriteExt;
 use tokio::net::TcpListener;
 use tokio::sync::broadcast;
-use tracing::{info, warn};
+use tracing::{error, info, warn};
 
-pub async fn run_tcp_server(
+use crate::broadcaster::TcpBroadcaster;
+
+pub async fn run_tcp_server<C, W>(
     addr: &str,
     broadcaster: Arc<TcpBroadcaster>,
-) -> Result<(), TcpServerError> {
+    tracker: Arc<ClientTracker>,
+    config: Arc<C>,
+    widget_states: Arc<W>,
+) -> Result<(), TcpServerError>
+where
+    C: ConfigRepository + Send + Sync + 'static,
+    C::Error: std::fmt::Debug + Send,
+    W: WidgetStateReader + Send + Sync + 'static,
+{
     let listener = TcpListener::bind(addr).await.map_err(TcpServerError::Io)?;
     info!(addr, "TCP server listening");
 
@@ -17,9 +29,21 @@ pub async fn run_tcp_server(
         let (mut socket, peer) = listener.accept().await.map_err(TcpServerError::Io)?;
         info!(%peer, "client connected");
 
+        tracker.add(peer);
+        let tracker = tracker.clone();
         let mut rx = broadcaster.subscribe();
 
+        let initial_frame = build_initial_frame(&*config, &*widget_states).await;
+
         tokio::spawn(async move {
+            if let Some(frame) = initial_frame
+                && socket.write_all(&frame).await.is_err()
+            {
+                info!(%peer, "client disconnected during initial send");
+                tracker.remove(peer);
+                return;
+            }
+
             loop {
                 match rx.recv().await {
                     Ok(frame) => {
@@ -34,6 +58,56 @@ pub async fn run_tcp_server(
                     }
                 }
             }
+            tracker.remove(peer);
         });
     }
 }
+
+async fn build_initial_frame<C, W>(config: &C, widget_states: &W) -> Option<Vec<u8>>
+where
+    C: ConfigRepository,
+    C::Error: std::fmt::Debug,
+    W: WidgetStateReader,
+{
+    let layout = match config.get_layout().await {
+        Ok(Some(l)) => l,
+        Ok(None) => return None,
+        Err(e) => {
+            error!(error = ?e, "failed to fetch layout for initial send");
+            return None;
+        }
+    };
+
+    let widgets = match config.list_widgets().await {
+        Ok(w) => w,
+        Err(e) => {
+            error!(error = ?e, "failed to fetch widgets for initial send");
+            return None;
+        }
+    };
+
+    let wire_layout: WireLayoutNode = (&layout.root).into();
+    let mut wire_widgets = Vec::new();
+    for w in &widgets {
+        if let Some(s) = widget_states.get_widget_state(w.id).await {
+            wire_widgets.push(WidgetDescriptor {
+                id: w.id,
+                display_hint: WireDisplayHint::IconValue,
+                state: (&s).into(),
+            });
+        }
+    }
+
+    let msg = ServerMessage::ScreenUpdate {
+        layout: wire_layout,
+        widgets: wire_widgets,
+    };
+
+    match encode(&msg) {
+        Ok(frame) => Some(frame),
+        Err(e) => {
+            error!(error = %e, "failed to encode initial screen update");
+            None
+        }
+    }
+}