Tray UI: start hidden, fixed window, grid layout, traffic + peers

Reworks the tray window per feedback and fills it in.

- Starts hidden in the tray (no window on launch); the window opens from the
  menu. On macOS the app now uses the Accessory activation policy, so it lives
  in the menu bar with no Dock icon (via a winit event-loop hook, pinned to
  eframe's winit). Fixed, non-resizable 360x600 window; the layout targets it.
- Tidied layout: top bar (title + refresh), a bottom panel with the join form
  and the action banner, and a scrolling list of network tiles between them.
  Labels and values sit on two-column grids so they align; the join name and
  secret inputs are the same fixed width.
- A ⟳ button beside the secret generates a fresh random secret
  (NetworkSecret::generate), for creating a network.
- Each network tile shows id, range, this device's address, peers
  (connected/known), the active and broadcast switches, a Leave button, and a
  collapsing "peers (N)" section with a formatted per-peer table (short key,
  address, handshake age, tx/rx packets, rate).
- Traffic: a new sampler turns the agent's cumulative packet counters into a
  packets-per-second rate per network and per peer, from the deltas between
  snapshots (the snapshot now carries a generation and timestamp so each
  refresh is sampled once). The network tile shows the current rate and a small
  hand-drawn sparkline of recent rates (no extra dependency).

Note: rates are packets/s — the report has no byte counters yet; bytes would
need an agent change. Builds and is clippy-clean (-D warnings) on macOS; the UI
has not been run in this headless session.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Cargo.lock

@@ -200,6 +200,12 @@ dependencies = [
  "rustversion",
 ]
 
+[[package]]
+name = "arrayref"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "76a2e8124351fda1ef8aaaa3bbd7ebbcb486bbcd4225aca0aa0d84bb2db8fecb"
+
 [[package]]
 name = "arrayvec"
 version = "0.7.8"
@@ -5175,6 +5181,19 @@ version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 
+[[package]]
+name = "sctk-adwaita"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6277f0217056f77f1d8f49f2950ac6c278c0d607c45f5ee99328d792ede24ec"
+dependencies = [
+ "ab_glyph",
+ "log",
+ "memmap2",
+ "smithay-client-toolkit 0.19.2",
+ "tiny-skia",
+]
+
 [[package]]
 name = "security-framework"
 version = "3.7.0"
@@ -5575,6 +5594,12 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
 
+[[package]]
+name = "strict-num"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6637bab7722d379c8b41ba849228d680cc12d0a45ba1fa2b48f2a30577a06731"
+
 [[package]]
 name = "strsim"
 version = "0.11.1"
@@ -5849,6 +5874,31 @@ dependencies = [
  "time-core",
 ]
 
+[[package]]
+name = "tiny-skia"
+version = "0.11.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "83d13394d44dae3207b52a326c0c85a8bf87f1541f23b0d143811088497b09ab"
+dependencies = [
+ "arrayref",
+ "arrayvec",
+ "bytemuck",
+ "cfg-if",
+ "log",
+ "tiny-skia-path",
+]
+
+[[package]]
+name = "tiny-skia-path"
+version = "0.11.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c9e7fc0c2e86a30b117d0462aa261b72b7a99b7ebd7deb3a14ceda95c5bdc93"
+dependencies = [
+ "arrayref",
+ "bytemuck",
+ "strict-num",
+]
+
 [[package]]
 name = "tinystr"
 version = "0.8.4"
@@ -6274,6 +6324,7 @@ dependencies = [
  "tracing-subscriber",
  "tray-icon",
  "tsunagi",
+ "winit",
 ]
 
 [[package]]
@@ -7365,6 +7416,7 @@ dependencies = [
  "raw-window-handle",
  "redox_syscall 0.4.1",
  "rustix 0.38.44",
+ "sctk-adwaita",
  "smithay-client-toolkit 0.19.2",
  "smol_str",
  "tracing",

crates/tsunagi-tray/Cargo.toml

@@ -25,5 +25,10 @@ tokio = { version = "1.53", features = ["rt", "rt-multi-thread", "sync", "time",
 tracing.workspace = true
 tracing-subscriber.workspace = true
 
+# macOS only: set the app's activation policy to Accessory so it lives in the
+# menu bar with no Dock icon. Pinned to eframe's winit so the types unify.
+[target.'cfg(target_os = "macos")'.dependencies]
+winit = "0.30"
+
 [lints]
 workspace = true

crates/tsunagi-tray/src/agent.rs

@@ -9,7 +9,7 @@
 
 use std::path::PathBuf;
 use std::sync::{Arc, Mutex};
-use std::time::Duration;
+use std::time::{Duration, Instant};
 
 use eframe::egui;
 use tokio::sync::mpsc;
@@ -43,6 +43,11 @@ pub(crate) struct Snapshot {
     pub last_action: Option<Result<String, String>>,
     /// Whether a command is currently being executed.
     pub busy: bool,
+    /// Bumped each time `status` is refreshed, so the UI can tell new data from
+    /// a repaint of the same data and sample traffic rates only on change.
+    pub generation: u64,
+    /// When this status was read, for computing rates between refreshes.
+    pub at: Option<Instant>,
 }
 
 /// Handle the UI holds: send commands, read the latest snapshot.
@@ -121,6 +126,8 @@ async fn refresh(socket: &std::path::Path, shared: &Arc<Mutex<Snapshot>>, ctx: &
     {
         let mut guard = lock(shared);
         guard.status = Some(status);
+        guard.generation = guard.generation.wrapping_add(1);
+        guard.at = Some(Instant::now());
     }
     ctx.request_repaint();
 }

crates/tsunagi-tray/src/app.rs

@@ -5,6 +5,7 @@ use std::time::Duration;
 use eframe::egui;
 
 use crate::agent::{AgentClient, resolve_socket};
+use crate::stats::Traffic;
 use crate::tray::{Action, Tray};
 use crate::ui::{self, JoinForm};
 
@@ -13,6 +14,11 @@ pub(crate) struct App {
     agent: AgentClient,
     tray: Tray,
     join: JoinForm,
+    /// Traffic rates derived from successive snapshots.
+    traffic: Traffic,
+    /// The snapshot generation last folded into `traffic`, so each refresh is
+    /// sampled exactly once rather than on every repaint.
+    sampled: u64,
     /// Set when the user chose Quit, so the next close actually exits instead
     /// of hiding to the tray.
     quitting: bool,
@@ -31,6 +37,8 @@ impl App {
             agent,
             tray,
             join: JoinForm::default(),
+            traffic: Traffic::default(),
+            sampled: 0,
             quitting: false,
         })
     }
@@ -58,7 +66,14 @@ impl eframe::App for App {
         }
 
         let snapshot = self.agent.snapshot();
-        ui::draw(ctx, &self.agent, &mut self.join, &snapshot);
+        // Fold each fresh status into the traffic rates exactly once.
+        if snapshot.generation != self.sampled
+            && let (Some(Ok(report)), Some(at)) = (&snapshot.status, snapshot.at)
+        {
+            self.traffic.observe(report, at);
+            self.sampled = snapshot.generation;
+        }
+        ui::draw(ctx, &self.agent, &mut self.join, &snapshot, &self.traffic);
 
         // Keep ticking so fresh status and tray actions are picked up even when
         // nothing else requests a repaint.

crates/tsunagi-tray/src/main.rs

@@ -11,6 +11,7 @@
 
 mod agent;
 mod app;
+mod stats;
 mod tray;
 mod ui;
 
@@ -28,14 +29,28 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         .build()?;
     let handle = runtime.handle().clone();
 
-    let options = eframe::NativeOptions {
+    #[cfg_attr(not(target_os = "macos"), expect(unused_mut))]
+    let mut options = eframe::NativeOptions {
+        // A fixed, small window; the whole layout targets this size.
         viewport: egui::ViewportBuilder::default()
             .with_title("tsunagi")
-            .with_inner_size([380.0, 540.0])
+            .with_inner_size([360.0, 600.0])
-            .with_min_inner_size([320.0, 360.0]),
+            .with_resizable(false)
+            // Start hidden: the app lives in the tray and the window opens from
+            // the menu.
+            .with_visible(false),
         ..Default::default()
     };
 
+    // macOS: live in the menu bar with no Dock icon (tray-only).
+    #[cfg(target_os = "macos")]
+    {
+        options.event_loop_builder = Some(Box::new(|builder| {
+            use winit::platform::macos::{ActivationPolicy, EventLoopBuilderExtMacOS};
+            builder.with_activation_policy(ActivationPolicy::Accessory);
+        }));
+    }
+
     eframe::run_native(
         "tsunagi",
         options,

crates/tsunagi-tray/src/stats.rs

@@ -0,0 +1,89 @@
+//! Traffic rates derived from successive status snapshots.
+//!
+//! The agent reports cumulative packet counters, not rates. The GUI samples
+//! them each time a fresh snapshot arrives and turns the deltas into a
+//! packets-per-second rate plus a short rolling history for a sparkline. One
+//! series per key: a network total, and each peer within it.
+
+use std::collections::{HashMap, VecDeque};
+use std::time::Instant;
+
+use tsunagi::ipc::StatusReport;
+
+/// How many rate samples to keep for a sparkline.
+const HISTORY: usize = 48;
+
+/// One series' rolling rate.
+#[derive(Default)]
+pub(crate) struct Series {
+    last: Option<(Instant, u64)>,
+    /// Most recent packets-per-second (tx + rx).
+    pub rate: f32,
+    /// Recent rates, oldest first, for a sparkline.
+    pub history: VecDeque<f32>,
+}
+
+impl Series {
+    fn sample(&mut self, now: Instant, total: u64) {
+        if let Some((then, previous)) = self.last {
+            let dt = now.saturating_duration_since(then).as_secs_f32();
+            if dt > 0.0 {
+                let delta = total.saturating_sub(previous) as f32;
+                self.rate = delta / dt;
+                self.history.push_back(self.rate);
+                while self.history.len() > HISTORY {
+                    self.history.pop_front();
+                }
+            }
+        }
+        self.last = Some((now, total));
+    }
+}
+
+/// All traffic series, keyed by a stable string.
+#[derive(Default)]
+pub(crate) struct Traffic {
+    series: HashMap<String, Series>,
+}
+
+impl Traffic {
+    /// Folds a fresh snapshot into the rates. Call once per new generation.
+    pub(crate) fn observe(&mut self, report: &StatusReport, now: Instant) {
+        for network in &report.networks {
+            let Some(overlay) = &network.overlay else {
+                continue;
+            };
+            let mut net_total = 0u64;
+            for peer in &overlay.peers {
+                let total = peer.tx_packets.saturating_add(peer.rx_packets);
+                net_total = net_total.saturating_add(total);
+                self.series
+                    .entry(peer_key(&network.network_id, &peer.public_key))
+                    .or_default()
+                    .sample(now, total);
+            }
+            self.series
+                .entry(net_key(&network.network_id))
+                .or_default()
+                .sample(now, net_total);
+        }
+    }
+
+    /// The network-total series, if sampled.
+    pub(crate) fn network(&self, network_id: &str) -> Option<&Series> {
+        self.series.get(&net_key(network_id))
+    }
+
+    /// One peer's series, if sampled.
+    pub(crate) fn peer(&self, network_id: &str, public_key: &str) -> Option<&Series> {
+        self.series.get(&peer_key(network_id, public_key))
+    }
+}
+
+fn net_key(network_id: &str) -> String {
+    format!("net:{network_id}")
+}
+
+fn peer_key(network_id: &str, public_key: &str) -> String {
+    format!("peer:{network_id}:{public_key}")
+}

crates/tsunagi-tray/src/ui.rs

@@ -1,15 +1,27 @@
 //! The window contents, drawn from the latest agent snapshot.
 //!
-//! Pure rendering: the current state comes from the snapshot, and a change to a
+//! Pure rendering: state comes from the snapshot and the traffic sampler, and a
-//! switch or a button sends a [`Command`] to the worker. egui is immediate
+//! change to a switch or a button sends a [`Command`] to the worker. The layout
-//! mode, so the switches reflect the agent's state and only a user change
+//! targets one fixed, small window, so everything is laid out on a grid and the
-//! dispatches a command.
+//! peer list hides behind a collapsing header.
+
+use std::collections::VecDeque;
 
 use eframe::egui;
 
-use tsunagi::ipc::{NetworkReport, StatusReport};
+use tsunagi::identity::NetworkSecret;
+use tsunagi::ipc::{NetworkReport, OverlayPeerReport, StatusReport};
 
 use crate::agent::{AgentClient, Command, Snapshot};
+use crate::stats::Traffic;
+
+/// Width of the value column's input fields, so name and secret line up.
+const INPUT_WIDTH: f32 = 208.0;
+/// Accent used for the traffic sparkline.
+const ACCENT: egui::Color32 = egui::Color32::from_rgb(0x2f, 0x80, 0xd8);
+const OK: egui::Color32 = egui::Color32::from_rgb(0x3c, 0xb0, 0x4a);
+const WARN: egui::Color32 = egui::Color32::from_rgb(0xd9, 0x9a, 0x00);
+const BAD: egui::Color32 = egui::Color32::from_rgb(0xd0, 0x4a, 0x3c);
 
 /// Join form state, kept across frames.
 #[derive(Default)]
@@ -24,8 +36,10 @@ pub(crate) fn draw(
     agent: &AgentClient,
     join: &mut JoinForm,
     snapshot: &Snapshot,
+    traffic: &Traffic,
 ) {
-    egui::CentralPanel::default().show(ctx, |ui| {
+    egui::TopBottomPanel::top("top").show(ctx, |ui| {
+        ui.add_space(4.0);
         ui.horizontal(|ui| {
             ui.heading("tsunagi");
             ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
@@ -37,89 +51,129 @@ pub(crate) fn draw(
                 }
             });
         });
+        ui.add_space(4.0);
+    });
 
-        match &snapshot.status {
+    egui::TopBottomPanel::bottom("bottom").show(ctx, |ui| {
-            None => {
+        if let Some(action) = &snapshot.last_action {
-                ui.add_space(8.0);
+            ui.add_space(4.0);
-                ui.label("Connecting to the agent…");
+            match action {
-            }
+                Ok(message) => ui.colored_label(OK, message),
-            Some(Err(error)) => draw_unreachable(ui, agent, error),
+                Err(error) => ui.colored_label(BAD, error),
-            Some(Ok(report)) => {
+            };
-                draw_header(ui, report);
+        }
-                ui.separator();
+        ui.add_space(4.0);
-                egui::ScrollArea::vertical().show(ui, |ui| {
+        draw_join(ui, agent, join);
+        ui.add_space(4.0);
+    });
+
+    egui::CentralPanel::default().show(ctx, |ui| match &snapshot.status {
+        None => {
+            ui.add_space(8.0);
+            ui.label("Connecting to the agent…");
+        }
+        Some(Err(error)) => draw_unreachable(ui, agent, error),
+        Some(Ok(report)) => {
+            draw_header(ui, report);
+            ui.separator();
+            egui::ScrollArea::vertical()
+                .auto_shrink([false, false])
+                .show(ui, |ui| {
                     if report.networks.is_empty() {
-                        ui.label("No networks yet. Join one below.");
+                        ui.add_space(6.0);
+                        ui.weak("No networks yet — join one below.");
                     }
                     for network in &report.networks {
-                        draw_network(ui, agent, network);
+                        draw_network(ui, agent, traffic, network);
                     }
                 });
-                ui.separator();
-                draw_join(ui, agent, join);
-            }
-        }
-
-        if let Some(action) = &snapshot.last_action {
-            ui.add_space(6.0);
-            match action {
-                Ok(message) => ui.colored_label(egui::Color32::from_rgb(0x3c, 0xb0, 0x4a), message),
-                Err(error) => ui.colored_label(egui::Color32::from_rgb(0xd0, 0x4a, 0x3c), error),
-            };
         }
     });
 }
 
-/// The "agent cannot be reached" state, with the socket it tried.
+/// The "agent cannot be reached" state, naming the socket it tried.
 fn draw_unreachable(ui: &mut egui::Ui, agent: &AgentClient, error: &str) {
     ui.add_space(8.0);
-    ui.colored_label(
+    ui.colored_label(BAD, "The agent is not reachable.");
-        egui::Color32::from_rgb(0xd0, 0x4a, 0x3c),
-        "The agent is not reachable.",
-    );
-    ui.add_space(4.0);
-    ui.label(format!("socket: {}", agent.socket().display()));
-    ui.label(error);
     ui.add_space(6.0);
-    ui.label(
+    kv(ui, "socket", &agent.socket().display().to_string());
+    ui.add_space(4.0);
+    ui.weak(error);
+    ui.add_space(6.0);
+    ui.weak(
         "Start the agent, or check that this user may open its control socket \
          (its group, mode 0660).",
     );
 }
 
-/// The device line: id, hostname, cache health.
+/// The device line.
 fn draw_header(ui: &mut egui::Ui, report: &StatusReport) {
     ui.add_space(4.0);
-    ui.label(format!("device  {}", short(&report.endpoint_id)));
+    egui::Grid::new("device")
-    ui.label(format!("host    {}", report.hostname));
+        .num_columns(2)
+        .spacing([10.0, 3.0])
+        .show(ui, |ui| {
+            kv_row(ui, "device", &short(&report.endpoint_id));
+            kv_row(ui, "host", &report.hostname);
+        });
     if !report.cache_healthy {
-        ui.colored_label(
+        ui.colored_label(WARN, "cache unavailable");
-            egui::Color32::from_rgb(0xd9, 0x9a, 0x00),
-            "cache unavailable",
-        );
     }
 }
 
-/// One network: name, range, this device's address, switches, peers, leave.
+/// One network tile.
-fn draw_network(ui: &mut egui::Ui, agent: &AgentClient, network: &NetworkReport) {
+fn draw_network(
+    ui: &mut egui::Ui,
+    agent: &AgentClient,
+    traffic: &Traffic,
+    network: &NetworkReport,
+) {
     ui.add_space(6.0);
-    ui.group(|ui| {
+    egui::Frame::group(ui.style()).show(ui, |ui| {
         ui.horizontal(|ui| {
             ui.strong(network.name.as_str());
             ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
-                if ui.button("Leave").clicked() {
+                if ui.small_button("Leave").clicked() {
                     agent.send(Command::Leave {
                         network_id: network.network_id.clone(),
                     });
                 }
             });
         });
-        ui.label(format!("id     {}", short(&network.network_id)));
+
-        if let Some(range) = &network.range {
+        let overlay = network.overlay.as_ref();
-            ui.label(format!("range  {range}"));
+        let address = overlay.and_then(|o| o.address.as_ref());
-        }
+        let series = traffic.network(&network.network_id);
-        if let Some(address) = network.overlay.as_ref().and_then(|o| o.address.as_ref()) {
+
-            ui.label(format!("addr   {address}"));
+        egui::Grid::new(("net", &network.network_id))
+            .num_columns(2)
+            .spacing([10.0, 3.0])
+            .show(ui, |ui| {
+                kv_row(ui, "id", &short(&network.network_id));
+                if let Some(range) = &network.range {
+                    kv_row(ui, "range", range);
+                }
+                if let Some(address) = address {
+                    kv_row(ui, "addr", address);
+                }
+                kv_row(
+                    ui,
+                    "peers",
+                    &format!(
+                        "{} connected · {} known",
+                        network.peers.len(),
+                        network.members.len()
+                    ),
+                );
+                if let Some(series) = series {
+                    kv_row(ui, "traffic", &rate(series.rate));
+                }
+            });
+
+        if let Some(series) = series
+            && series.history.len() >= 2
+        {
+            sparkline(ui, &series.history);
         }
 
         ui.horizontal(|ui| {
@@ -139,26 +193,81 @@ fn draw_network(ui: &mut egui::Ui, agent: &AgentClient, network: &NetworkReport)
             }
         });
 
-        let connected = network.peers.len();
+        if let Some(overlay) = overlay
-        let known = network.members.len();
+            && !overlay.peers.is_empty()
-        ui.label(format!("peers  {connected} connected · {known} known"));
+        {
+            egui::CollapsingHeader::new(format!("peers ({})", overlay.peers.len()))
+                .id_salt(("peers", &network.network_id))
+                .show(ui, |ui| {
+                    draw_peers(ui, traffic, &network.network_id, &overlay.peers);
+                });
+        }
     });
 }
 
-/// The join form: name + secret + button.
+/// The per-peer table inside a network's collapsing header.
+fn draw_peers(ui: &mut egui::Ui, traffic: &Traffic, network_id: &str, peers: &[OverlayPeerReport]) {
+    egui::Grid::new(("peertable", network_id))
+        .num_columns(5)
+        .striped(true)
+        .spacing([10.0, 3.0])
+        .show(ui, |ui| {
+            for header in ["peer", "address", "age", "tx/rx", "rate"] {
+                ui.weak(header);
+            }
+            ui.end_row();
+
+            for peer in peers {
+                ui.monospace(short(&peer.public_key));
+                ui.label(peer.address.clone().unwrap_or_else(|| "—".into()));
+                ui.label(match peer.handshake_secs_ago {
+                    Some(secs) => format!("{secs}s"),
+                    None => "—".into(),
+                });
+                ui.label(format!("{}/{}", peer.tx_packets, peer.rx_packets));
+                let pps = traffic
+                    .peer(network_id, &peer.public_key)
+                    .map_or(0.0, |series| series.rate);
+                ui.label(rate(pps));
+                ui.end_row();
+            }
+        });
+}
+
+/// The join form: aligned name and secret, a generate button, and Join.
 fn draw_join(ui: &mut egui::Ui, agent: &AgentClient, join: &mut JoinForm) {
-    ui.add_space(4.0);
+    ui.label("Join or create a network");
-    ui.label("Join a network");
+    egui::Grid::new("join")
-    ui.horizontal(|ui| {
+        .num_columns(2)
-        ui.label("name");
+        .spacing([8.0, 6.0])
-        ui.text_edit_singleline(&mut join.name);
+        .show(ui, |ui| {
-    });
+            ui.label("name");
-    ui.horizontal(|ui| {
+            ui.add(egui::TextEdit::singleline(&mut join.name).desired_width(INPUT_WIDTH));
-        ui.label("secret");
+            ui.end_row();
-        ui.add(egui::TextEdit::singleline(&mut join.secret).password(true));
+
-    });
+            ui.label("secret");
+            ui.horizontal(|ui| {
+                ui.add(
+                    egui::TextEdit::singleline(&mut join.secret)
+                        .desired_width(INPUT_WIDTH - 26.0)
+                        .password(true),
+                );
+                if ui
+                    .button("⟳")
+                    .on_hover_text("Generate a new random secret")
+                    .clicked()
+                {
+                    join.secret = NetworkSecret::generate().encode().as_str().to_owned();
+                }
+            });
+            ui.end_row();
+        });
+
     let ready = !join.name.trim().is_empty() && !join.secret.trim().is_empty();
-    if ui.add_enabled(ready, egui::Button::new("Join")).clicked() {
+    if ui
+        .add_enabled(ready, egui::Button::new("Join / create"))
+        .clicked()
+    {
         agent.send(Command::Join {
             name: join.name.trim().to_string(),
             secret: join.secret.trim().to_string(),
@@ -167,6 +276,55 @@ fn draw_join(ui: &mut egui::Ui, agent: &AgentClient, join: &mut JoinForm) {
     }
 }
 
+/// A small filled-ish line chart of recent rates, drawn with the painter.
+fn sparkline(ui: &mut egui::Ui, history: &VecDeque<f32>) {
+    let width = ui.available_width();
+    let (rect, _) = ui.allocate_exact_size(egui::vec2(width, 26.0), egui::Sense::hover());
+    let painter = ui.painter_at(rect);
+    let peak = history.iter().copied().fold(1.0_f32, f32::max);
+    let count = history.len();
+    if count < 2 {
+        return;
+    }
+    let points: Vec<egui::Pos2> = history
+        .iter()
+        .enumerate()
+        .map(|(i, value)| {
+            let x = rect.left() + rect.width() * (i as f32 / (count - 1) as f32);
+            let y = rect.bottom() - (rect.height() - 2.0) * (value / peak);
+            egui::pos2(x, y)
+        })
+        .collect();
+    painter.add(egui::Shape::line(
+        points,
+        egui::Stroke::new(1.5_f32, ACCENT),
+    ));
+}
+
+/// A key/value label pair outside a grid.
+fn kv(ui: &mut egui::Ui, key: &str, value: &str) {
+    ui.horizontal(|ui| {
+        ui.weak(key);
+        ui.monospace(value);
+    });
+}
+
+/// A key/value row inside a two-column grid.
+fn kv_row(ui: &mut egui::Ui, key: &str, value: &str) {
+    ui.weak(key);
+    ui.label(value);
+    ui.end_row();
+}
+
+/// Formats a packets-per-second rate.
+fn rate(pps: f32) -> String {
+    if pps >= 1000.0 {
+        format!("{:.1}k pkt/s", pps / 1000.0)
+    } else {
+        format!("{pps:.0} pkt/s")
+    }
+}
+
 /// A short, readable prefix of a long identifier (char-safe, no panic).
 fn short(id: &str) -> String {
     const KEEP: usize = 12;