[fix](trx-core): expose rig min tuning step and align UI tuning

Add min_freq_step_hz to RigCapabilities, set backend values, and make HTTP frontend parse suffix-less frequency input using the selected unit while snapping set/jog frequencies to rig step granularity.

Co-authored-by: Codex <codex@openai.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>

src/trx-client/src/remote_client.rs

@@ -371,6 +371,7 @@ mod tests {
                 model: "Dummy".to_string(),
                 revision: "1".to_string(),
                 capabilities: RigCapabilities {
+                    min_freq_step_hz: 1,
                     supported_bands: vec![Band {
                         low_hz: 7_000_000,
                         high_hz: 7_200_000,

src/trx-client/trx-frontend/trx-frontend-http-json/src/server.rs

@@ -294,6 +294,7 @@ mod tests {
                 model: "Dummy".to_string(),
                 revision: "1".to_string(),
                 capabilities: RigCapabilities {
+                    min_freq_step_hz: 1,
                     supported_bands: vec![Band {
                         low_hz: 14_000_000,
                         high_hz: 14_350_000,

src/trx-client/trx-frontend/trx-frontend-http/assets/web/app.js

@@ -45,6 +45,7 @@ let sigMeasuring = false;
 let sigSamples = [];
 let lastFreqHz = null;
 let jogStep = loadSetting("jogStep", 1000);
+let minFreqStepHz = 1;
 const VFO_COLORS = ["var(--accent-green)", "var(--accent-yellow)"];
 function vfoColor(idx) {
   if (idx < VFO_COLORS.length) return VFO_COLORS[idx];
@@ -89,9 +90,9 @@ function formatFreq(hz) {
 
 function formatFreqForStep(hz, step) {
   if (!Number.isFinite(hz)) return "--";
-  if (step === 1_000_000) return (hz / 1_000_000).toFixed(6);
+  if (step >= 1_000_000) return (hz / 1_000_000).toFixed(6);
-  if (step === 1_000) return (hz / 1_000).toFixed(3);
+  if (step >= 1_000) return (hz / 1_000).toFixed(3);
-  if (step === 1) return String(Math.round(hz));
+  if (step >= 1) return String(Math.round(hz));
   return formatFreq(hz);
 }
 
@@ -116,11 +117,11 @@ function parseFreqInput(val, defaultStep) {
     num *= 1_000;
   } else if (!unit) {
     // Use currently selected input unit when user omits suffix.
-    if (defaultStep === 1_000_000) {
+    if (defaultStep >= 1_000_000) {
       num *= 1_000_000;
-    } else if (defaultStep === 1_000) {
+    } else if (defaultStep >= 1_000) {
       num *= 1_000;
-    } else if (defaultStep === 1) {
+    } else if (defaultStep >= 1) {
       // already Hz
     } else {
       // Fallback heuristic.
@@ -136,6 +137,54 @@ function parseFreqInput(val, defaultStep) {
   return Math.round(num);
 }
 
+function normalizeMinFreqStep(cap) {
+  const val = Number(cap && cap.min_freq_step_hz);
+  if (!Number.isFinite(val) || val < 1) return 1;
+  return Math.round(val);
+}
+
+function alignFreqToRigStep(hz) {
+  if (!Number.isFinite(hz)) return hz;
+  const step = Math.max(1, minFreqStepHz);
+  return Math.round(hz / step) * step;
+}
+
+function updateJogStepSupport(cap) {
+  const nextMinStep = normalizeMinFreqStep(cap);
+  minFreqStepHz = nextMinStep;
+
+  const stepRoot = document.getElementById("jog-step");
+  if (!stepRoot) return;
+  const buttons = Array.from(stepRoot.querySelectorAll("button[data-step]"));
+  if (buttons.length === 0) return;
+
+  buttons.forEach((btn) => {
+    const base = Number(btn.dataset.baseStep || btn.dataset.step);
+    if (Number.isFinite(base) && base > 0) {
+      btn.dataset.baseStep = String(Math.round(base));
+      btn.dataset.step = String(Math.max(Math.round(base), minFreqStepHz));
+    }
+  });
+
+  const steps = buttons
+    .map((btn) => Number(btn.dataset.step))
+    .filter((s) => Number.isFinite(s) && s > 0);
+  if (steps.length === 0) return;
+
+  const current = Number(jogStep);
+  const desired =
+    Number.isFinite(current) && current >= minFreqStepHz ? current : Math.max(steps[0], minFreqStepHz);
+
+  jogStep = steps.reduce((best, s) => (Math.abs(s - desired) < Math.abs(best - desired) ? s : best), steps[0]);
+  saveSetting("jogStep", jogStep);
+
+  buttons.forEach((btn) => {
+    btn.classList.toggle("active", Number(btn.dataset.step) === jogStep);
+  });
+
+  refreshFreqDisplay();
+}
+
 function normalizeMode(modeVal) {
   if (typeof modeVal === "string") return modeVal;
   if (modeVal && typeof modeVal === "object") {
@@ -256,6 +305,7 @@ function render(update) {
     }
   }
   if (update.info && update.info.capabilities) {
+    updateJogStepSupport(update.info.capabilities);
     updateSupportedBands(update.info.capabilities);
   }
   if (update.status && update.status.freq && typeof update.status.freq.hz === "number") {
@@ -572,7 +622,8 @@ pttBtn.addEventListener("click", async () => {
 });
 
 freqBtn.addEventListener("click", async () => {
-  const parsed = parseFreqInput(freqEl.value, jogStep);
+  const parsedRaw = parseFreqInput(freqEl.value, jogStep);
+  const parsed = alignFreqToRigStep(parsedRaw);
   if (parsed === null) {
     showHint("Freq missing", 1500);
     return;
@@ -612,7 +663,7 @@ const jogStepEl = document.getElementById("jog-step");
 async function jogFreq(direction) {
   if (lastLocked) { showHint("Locked", 1500); return; }
   if (lastFreqHz === null) return;
-  const newHz = lastFreqHz + direction * jogStep;
+  const newHz = alignFreqToRigStep(lastFreqHz + direction * jogStep);
   if (!freqAllowed(newHz)) {
     showHint("Out of supported bands", 1500);
     return;
@@ -679,7 +730,7 @@ window.addEventListener("mouseup", () => {
 jogStepEl.addEventListener("click", (e) => {
   const btn = e.target.closest("button[data-step]");
   if (!btn) return;
-  jogStep = parseInt(btn.dataset.step, 10);
+  jogStep = Math.max(parseInt(btn.dataset.step, 10), minFreqStepHz);
   jogStepEl.querySelectorAll("button").forEach((b) => b.classList.remove("active"));
   btn.classList.add("active");
   saveSetting("jogStep", jogStep);
@@ -687,9 +738,17 @@ jogStepEl.addEventListener("click", (e) => {
 });
 
 // Restore active jog step button from saved setting
-jogStepEl.querySelectorAll("button").forEach((b) => {
+{
-  b.classList.toggle("active", parseInt(b.dataset.step, 10) === jogStep);
+  const buttons = Array.from(jogStepEl.querySelectorAll("button[data-step]"));
-});
+  const active =
+    buttons.find((b) => parseInt(b.dataset.step, 10) === jogStep) ||
+    buttons.find((b) => parseInt(b.dataset.step, 10) === 1000) ||
+    buttons[0];
+  if (active) {
+    jogStep = parseInt(active.dataset.step, 10);
+    buttons.forEach((b) => b.classList.toggle("active", b === active));
+  }
+}
 
 modeBtn.addEventListener("click", async () => {
   const mode = modeEl.value || "";

src/trx-client/trx-frontend/trx-frontend-http/src/api.rs

@@ -614,6 +614,7 @@ impl From<RigInfoPlaceholder> for RigInfo {
             model: "Rig".to_string(),
             revision: "".to_string(),
             capabilities: RigCapabilities {
+                min_freq_step_hz: 1,
                 supported_bands: vec![],
                 supported_modes: vec![],
                 num_vfos: 0,

src/trx-core/src/rig/controller/handlers.rs

@@ -542,6 +542,7 @@ mod tests {
                     model: "Mock".to_string(),
                     revision: "1.0".to_string(),
                     capabilities: RigCapabilities {
+                        min_freq_step_hz: 1,
                         supported_bands: vec![],
                         supported_modes: vec![],
                         num_vfos: 2,
@@ -595,6 +596,7 @@ mod tests {
                     model: "Mock".to_string(),
                     revision: "1.0".to_string(),
                     capabilities: RigCapabilities {
+                        min_freq_step_hz: 1,
                         supported_bands: vec![],
                         supported_modes: vec![],
                         num_vfos: 2,

src/trx-core/src/rig/controller/machine.rs

@@ -439,6 +439,7 @@ mod tests {
             model: "Mock".to_string(),
             revision: "1.0".to_string(),
             capabilities: RigCapabilities {
+                min_freq_step_hz: 1,
                 supported_bands: vec![],
                 supported_modes: vec![],
                 num_vfos: 2,

src/trx-core/src/rig/mod.rs

@@ -39,6 +39,8 @@ pub struct RigInfo {
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct RigCapabilities {
+    #[serde(default = "default_min_freq_step_hz")]
+    pub min_freq_step_hz: u64,
     pub supported_bands: Vec<Band>,
     pub supported_modes: Vec<RigMode>,
     pub num_vfos: usize,
@@ -51,6 +53,10 @@ pub struct RigCapabilities {
     pub split: bool,
 }
 
+fn default_min_freq_step_hz() -> u64 {
+    1
+}
+
 /// Common interface for rig backends.
 pub trait Rig {
     fn info(&self) -> &RigInfo;

src/trx-server/src/listener.rs

@@ -344,6 +344,7 @@ mod tests {
             model: "Dummy".to_string(),
             revision: "1".to_string(),
             capabilities: RigCapabilities {
+                min_freq_step_hz: 1,
                 supported_bands: vec![Band {
                     low_hz: 7_000_000,
                     high_hz: 7_200_000,

src/trx-server/trx-backend/src/dummy.rs

@@ -37,6 +37,7 @@ impl DummyRig {
                 model: "dummy".to_string(),
                 revision: "1.0".to_string(),
                 capabilities: RigCapabilities {
+                    min_freq_step_hz: 1,
                     supported_bands: vec![
                         Band {
                             low_hz: 1_800_000,

src/trx-server/trx-backend/trx-backend-ft450d/src/lib.rs

@@ -36,6 +36,7 @@ impl Ft450d {
             model: "FT-450D".to_string(),
             revision: "".to_string(),
             capabilities: RigCapabilities {
+                min_freq_step_hz: 10,
                 supported_bands: vec![
                     // Transmit-capable amateur bands (HF + 6m)
                     Band {

src/trx-server/trx-backend/trx-backend-ft817/src/lib.rs

@@ -37,6 +37,7 @@ impl Ft817 {
             model: "FT-817".to_string(),
             revision: "".to_string(),
             capabilities: RigCapabilities {
+                min_freq_step_hz: 10,
                 supported_bands: vec![
                     // Transmit-capable amateur bands
                     Band {