feat(kpa1500): enable toggle + separate configuration window (FR-AMP-01)

CHANGELOG.md

@@ -10,6 +10,19 @@ during the 0.4.0 release, so earlier detail lives in the git history and in the
 change ledgers under [`docs/test/test-strategy.md`](docs/test/test-strategy.md)
 and [`docs/requirements/system-requirements.md`](docs/requirements/system-requirements.md).
 
+## [Unreleased]
+
+### Added
+
+- **KPA1500 amplifier support (opt-in).** A new **KPA1500** section in Settings
+  with an enable toggle and a **Configuration…** button that opens a separate
+  window for the amplifier's connection — host, port (default 1500) and poll
+  interval. Off by default; your settings are saved. This first step wires the
+  connection to the amp's own Ethernet control server (a second link alongside
+  the K4); live amplifier metering and control follow in a later release. Only
+  the KPA1500 is supported — the KPA500 and KAT500 have no network interface of
+  their own.
+
 ## [0.9.0] — 2026-07-27
 
 ### Added

app/src/main.rs

@@ -80,6 +80,17 @@ fn diag_window_settings() -> iced::window::Settings {
     }
 }
 
+/// The detached KPA1500 configuration window (FR-AMP-01): a small fixed dialog
+/// for the amplifier's host/port/poll settings.
+fn kpa1500_window_settings() -> iced::window::Settings {
+    iced::window::Settings {
+        size: iced::Size::new(420.0, 320.0),
+        resizable: false,
+        icon: app_icon(),
+        ..Default::default()
+    }
+}
+
 struct App {
     // connection form
     host: String,
@@ -205,6 +216,15 @@ struct App {
     main_window: iced::window::Id,
     diag_window: Option<iced::window::Id>,
     diag_enabled: bool,
+    // KPA1500 amplifier support (FR-AMP-01): an opt-in toggle plus a detached
+    // configuration window (host/port/poll) for the amp's own Ethernet CAT
+    // server. The window id is present only while the dialog is open; the
+    // enable flag and the connection settings persist.
+    kpa1500_config_window: Option<iced::window::Id>,
+    kpa1500_enabled: bool,
+    kpa1500_host: String,
+    kpa1500_port: String,
+    kpa1500_poll: String,
     // Diagnostics log: show/hide + follow-newest (auto-scroll).
     show_log: bool,
     log_autoscroll: bool,
@@ -757,6 +777,12 @@ enum Message {
     ToggleDiagWindow,
     WindowOpened,
     WindowClosed(iced::window::Id),
+    // KPA1500 amplifier support (FR-AMP-01).
+    ToggleKpa1500,
+    ToggleKpa1500Window,
+    Kpa1500HostChanged(String),
+    Kpa1500PortChanged(String),
+    Kpa1500PollChanged(String),
     ToggleLogAutoscroll,
     LogFilterChanged(String),
     /// A text-editor action from the read-only log view (selection/scroll; edits
@@ -881,6 +907,10 @@ impl App {
         let auto_update_check = prefs.auto_update_check;
         let diag_enabled = prefs.diagnostics_window;
         let tooltips = prefs.tooltips;
+        let kpa1500_enabled = prefs.kpa1500_enabled;
+        let kpa1500_host = prefs.kpa1500_host.clone();
+        let kpa1500_port = prefs.kpa1500_port.to_string();
+        let kpa1500_poll = prefs.kpa1500_poll_ms.to_string();
 
         // Open the main window; the daemon starts with none (FR-DIAG-04).
         let (main_window, open_main) = iced::window::open(iced::window::Settings {
@@ -994,6 +1024,12 @@ impl App {
             main_window,
             diag_window,
             diag_enabled,
+            // The config window opens on demand, not at start-up.
+            kpa1500_config_window: None,
+            kpa1500_enabled,
+            kpa1500_host,
+            kpa1500_port,
+            kpa1500_poll,
             show_log: false,
             log_autoscroll: true,
             log_refresh_div: 0,
@@ -1353,6 +1389,22 @@ impl App {
                     ptt_toggle: self.ptt_toggle,
                     mode_aware_ui: self.mode_aware_ui,
                     auto_update_check: self.auto_update_check,
+                    kpa1500_enabled: self.kpa1500_enabled,
+                    kpa1500_host: self.kpa1500_host.clone(),
+                    // An empty or out-of-range field falls back to the default
+                    // rather than persisting a value the amp can't use.
+                    kpa1500_port: self
+                        .kpa1500_port
+                        .parse::<u16>()
+                        .ok()
+                        .filter(|p| *p != 0)
+                        .unwrap_or(1500),
+                    kpa1500_poll_ms: self
+                        .kpa1500_poll
+                        .parse::<u16>()
+                        .ok()
+                        .filter(|ms| *ms >= 50)
+                        .unwrap_or(500),
                     kpod_enabled: self.kpod_enabled,
                     kpod_buttons: self.kpod_buttons.clone(),
                     ..Default::default()
@@ -2126,6 +2178,13 @@ impl App {
                         return iced::window::close(id);
                     }
                 }
+                // ESC in the KPA1500 config window closes that window (FR-AMP-01).
+                if is_esc && self.kpa1500_config_window == Some(window) {
+                    if let Some(id) = self.kpa1500_config_window.take() {
+                        self.save_config();
+                        return iced::window::close(id);
+                    }
+                }
                 // ESC dismisses an open modal (Settings / About, FR-UI-23) or
                 // cancels an in-progress hotkey capture, before other key handling.
                 if matches!(
@@ -2428,6 +2487,38 @@ impl App {
                     self.diag_enabled = false;
                     self.save_config();
                 }
+                if Some(id) == self.kpa1500_config_window {
+                    // Closing the config window persists whatever was edited;
+                    // the enable toggle and settings survive independently.
+                    self.kpa1500_config_window = None;
+                    self.save_config();
+                }
+            }
+            // KPA1500 support (FR-AMP-01): the enable toggle, the detached
+            // configuration window, and its host/port/poll fields.
+            Message::ToggleKpa1500 => {
+                self.kpa1500_enabled = !self.kpa1500_enabled;
+                self.save_config();
+            }
+            Message::ToggleKpa1500Window => {
+                if let Some(id) = self.kpa1500_config_window.take() {
+                    self.save_config();
+                    return iced::window::close(id);
+                }
+                let (id, open) = iced::window::open(kpa1500_window_settings());
+                self.kpa1500_config_window = Some(id);
+                return open.map(|_| Message::WindowOpened);
+            }
+            Message::Kpa1500HostChanged(v) => {
+                self.kpa1500_host = v.trim().to_string();
+            }
+            Message::Kpa1500PortChanged(v) => {
+                // Keep only digits so the field can never hold an unparseable
+                // port; an empty field falls back to the default on save.
+                self.kpa1500_port = v.chars().filter(char::is_ascii_digit).take(5).collect();
+            }
+            Message::Kpa1500PollChanged(v) => {
+                self.kpa1500_poll = v.chars().filter(char::is_ascii_digit).take(5).collect();
             }
             Message::ToggleLogAutoscroll => {
                 self.log_autoscroll = !self.log_autoscroll;
@@ -5957,10 +6048,88 @@ impl App {
             .into()
     }
 
+    /// The detached KPA1500 configuration window body (FR-AMP-01): the enable
+    /// toggle plus the amplifier's connection settings. Editing a field updates
+    /// its buffer; closing the window (Done / ESC / the window control) persists
+    /// via `save_config`. Telemetry and control land in a later change — this
+    /// window is the enable + connection surface.
+    fn kpa1500_config_view(&self) -> Element<'_, Message> {
+        set_active_theme(self.effective_theme());
+        let dim = role_color(ui::ColorRole::Inactive);
+        let label = |t: &'static str| Text::new(t).size(12).width(Length::Fixed(72.0));
+        let host_row = Row::new()
+            .spacing(8)
+            .align_y(Alignment::Center)
+            .push(label("Host"))
+            .push(
+                TextInput::new("IP or hostname", &self.kpa1500_host)
+                    .on_input(Message::Kpa1500HostChanged)
+                    .size(13)
+                    .width(Length::Fixed(210.0)),
+            );
+        let port_row = Row::new()
+            .spacing(8)
+            .align_y(Alignment::Center)
+            .push(label("Port"))
+            .push(
+                TextInput::new("1500", &self.kpa1500_port)
+                    .on_input(Message::Kpa1500PortChanged)
+                    .size(13)
+                    .width(Length::Fixed(90.0)),
+            );
+        let poll_row = Row::new()
+            .spacing(8)
+            .align_y(Alignment::Center)
+            .push(label("Poll (ms)"))
+            .push(
+                TextInput::new("500", &self.kpa1500_poll)
+                    .on_input(Message::Kpa1500PollChanged)
+                    .size(13)
+                    .width(Length::Fixed(90.0)),
+            );
+        let col = Column::new()
+            .spacing(12)
+            .push(Text::new("KPA1500 Amplifier").size(16))
+            .push(
+                Text::new(
+                    "Connects to the amplifier's own Ethernet remote-control \
+                     server — a second link alongside the K4.",
+                )
+                .size(11)
+                .color(dim),
+            )
+            .push(small_btn_pair(
+                self.kpa1500_enabled,
+                "Support: ON",
+                "Support: OFF",
+                Message::ToggleKpa1500,
+            ))
+            .push(host_row)
+            .push(port_row)
+            .push(poll_row)
+            .push(
+                Container::new(
+                    Row::new()
+                        .push(horizontal_space())
+                        .push(small_btn("Done", Message::ToggleKpa1500Window)),
+                )
+                .width(Length::Fill)
+                .padding([8, 0]),
+            );
+        Container::new(col)
+            .style(panel_style)
+            .padding(16)
+            .width(Length::Fill)
+            .height(Length::Fill)
+            .into()
+    }
+
     /// Per-window title (daemon).
     fn title(&self, window: iced::window::Id) -> String {
         if Some(window) == self.diag_window {
             "K4 Remote — Diagnostics".into()
+        } else if Some(window) == self.kpa1500_config_window {
+            "K4 Remote — KPA1500".into()
         } else {
             "K4 Remote".into()
         }
@@ -5973,6 +6142,10 @@ impl App {
         if Some(window) == self.diag_window {
             return self.diag_window_view();
         }
+        // The detached KPA1500 configuration window (FR-AMP-01).
+        if Some(window) == self.kpa1500_config_window {
+            return self.kpa1500_config_view();
+        }
         let dim = role_color(ui::ColorRole::Inactive);
 
         // Header band: title, link state, status line, the A / B / A+B view
@@ -7202,6 +7375,19 @@ impl App {
             .push(self.backup_section_view())
             .push(Text::new("K-Pod function switches").size(12).color(dim))
             .push(self.kpod_buttons_view())
+            .push(Text::new("KPA1500 amplifier").size(12).color(dim))
+            .push(
+                Row::new()
+                    .spacing(8)
+                    .align_y(Alignment::Center)
+                    .push(small_btn_pair(
+                        self.kpa1500_enabled,
+                        "Support: ON",
+                        "Support: OFF",
+                        Message::ToggleKpa1500,
+                    ))
+                    .push(small_btn("Configuration…", Message::ToggleKpa1500Window)),
+            )
             .push(
                 Container::new(
                     Row::new()

crates/k4-config/src/lib.rs

@@ -121,6 +121,22 @@ pub struct Prefs {
     /// is found.
     #[serde(default = "default_true")]
     pub auto_update_check: bool,
+    /// Enable KPA1500 linear-amplifier support (FR-AMP-01). Default off
+    /// (opt-in). When on, the app talks to the amp over its **own** Ethernet
+    /// CAT server — a second connection alongside the K4 link, not the K4's
+    /// one-way `EC` passthrough. Host/port/poll are set in the separate
+    /// KPA1500 configuration window.
+    #[serde(default)]
+    pub kpa1500_enabled: bool,
+    /// KPA1500 remote-head host (IP or hostname). Empty until configured.
+    #[serde(default)]
+    pub kpa1500_host: String,
+    /// KPA1500 remote-head TCP command-server port. Default 1500.
+    #[serde(default = "default_kpa1500_port")]
+    pub kpa1500_port: u16,
+    /// KPA1500 telemetry poll interval, milliseconds. Default 500.
+    #[serde(default = "default_kpa1500_poll_ms")]
+    pub kpa1500_poll_ms: u16,
     /// Enable the Elecraft K-Pod USB control surface. Default off (opt-in); the
     /// app runs normally whether or not a K-Pod is attached.
     #[serde(default)]
@@ -344,6 +360,16 @@ fn default_true() -> bool {
     true
 }
 
+/// The KPA1500's TCP command-server port (its remote-head interface).
+fn default_kpa1500_port() -> u16 {
+    1500
+}
+
+/// Default KPA1500 telemetry poll interval, milliseconds.
+fn default_kpa1500_poll_ms() -> u16 {
+    500
+}
+
 impl Default for Prefs {
     fn default() -> Self {
         Self {
@@ -366,6 +392,10 @@ impl Default for Prefs {
             ptt_toggle: true,
             mode_aware_ui: true,
             auto_update_check: true,
+            kpa1500_enabled: false,
+            kpa1500_host: String::new(),
+            kpa1500_port: 1500,
+            kpa1500_poll_ms: 500,
             kpod_enabled: false,
             kpod_buttons: default_kpod_buttons(),
         }

crates/k4-config/tests/config.rs

@@ -267,3 +267,38 @@ fn fr_ui_upd_02_auto_update_check_defaults_on_and_persists() {
     let back: Prefs = toml::from_str(&toml).expect("deserialize");
     assert!(!back.auto_update_check, "opt-out is remembered");
 }
+
+/// KPA1500 support is opt-in (default off) with a sensible default port/poll,
+/// and the enable flag plus the connection settings survive a save/load
+/// round-trip so the operator configures the amp once.
+/// trace: FR-AMP-01
+#[test]
+fn fr_amp_01_kpa1500_defaults_off_and_persists() {
+    let def = Prefs::default();
+    assert!(!def.kpa1500_enabled, "default opt-in: support is off");
+    assert_eq!(def.kpa1500_port, 1500, "the amp's command-server port");
+    assert_eq!(def.kpa1500_poll_ms, 500);
+    assert!(def.kpa1500_host.is_empty());
+
+    // A configured amp round-trips through TOML unchanged.
+    let prefs = Prefs {
+        kpa1500_enabled: true,
+        kpa1500_host: "192.168.1.50".into(),
+        kpa1500_port: 1500,
+        kpa1500_poll_ms: 250,
+        ..Default::default()
+    };
+    let toml = toml::to_string(&prefs).expect("serialize");
+    let back: Prefs = toml::from_str(&toml).expect("deserialize");
+    assert!(back.kpa1500_enabled);
+    assert_eq!(back.kpa1500_host, "192.168.1.50");
+    assert_eq!(back.kpa1500_port, 1500);
+    assert_eq!(back.kpa1500_poll_ms, 250);
+
+    // A config written before this feature (no KPA fields) loads with the
+    // opt-in default off — never surprising an upgrader with an amp link.
+    let legacy = "tune_step_hz = 100";
+    let old: Prefs = toml::from_str(legacy).expect("legacy config");
+    assert!(!old.kpa1500_enabled);
+    assert_eq!(old.kpa1500_port, 1500);
+}