diff --git a/src-tauri/src/extension_server.rs b/src-tauri/src/extension_server.rs
index f06c9c4..a48bbab 100644
--- a/src-tauri/src/extension_server.rs
+++ b/src-tauri/src/extension_server.rs
@@ -203,7 +203,15 @@ async fn ping_handler(
         None => return Err(StatusCode::FORBIDDEN),
     };
 
-    if verify_signature(signature, timestamp_str, &body, &state.pairing_token).is_err() {
+    let timestamp = match verify_signature(signature, timestamp_str, &body, &state.pairing_token) {
+        Ok(timestamp) => timestamp,
+        Err(_) => return Err(StatusCode::FORBIDDEN),
+    };
+
+    // Discovery probes are authenticated requests too. Claim the verified
+    // signature before signing a proof so a captured /ping signature cannot
+    // be replayed with arbitrary client nonces during its validity window.
+    if !claim_request(signature, timestamp, &state.replay_cache) {
         return Err(StatusCode::FORBIDDEN);
     }
 
diff --git a/src/components/SpeedLimiterView.test.ts b/src/components/SpeedLimiterView.test.ts
index 176d3f5..e4a7cc8 100644
--- a/src/components/SpeedLimiterView.test.ts
+++ b/src/components/SpeedLimiterView.test.ts
@@ -1,5 +1,9 @@
 import { describe, expect, it } from 'vitest';
-import { displayValueFromPresetBase, presetBaseFromDisplayValue } from './SpeedLimiterView';
+import {
+  convertSpeedValue,
+  displayValueFromPresetBase,
+  presetBaseFromDisplayValue,
+} from './SpeedLimiterView';
 
 describe('SpeedLimiterView speed conversions', () => {
   it('converts KB/s and MB/s using binary units consistently', () => {
@@ -8,4 +12,12 @@ describe('SpeedLimiterView speed conversions', () => {
     expect(presetBaseFromDisplayValue(5, 'MB/s')).toBe(5);
     expect(displayValueFromPresetBase(5, 'MB/s')).toBe(5);
   });
+
+  it('round-trips non-MiB-aligned presets through the integer KiB backend value', () => {
+    const presetBase = presetBaseFromDisplayValue(1500, 'KB/s');
+
+    expect(displayValueFromPresetBase(presetBase, 'KB/s')).toBe(1500);
+    expect(convertSpeedValue(1500, 'KB/s', 'MB/s')).toBe(1500 / 1024);
+    expect(convertSpeedValue(convertSpeedValue(1500, 'KB/s', 'MB/s'), 'MB/s', 'KB/s')).toBe(1500);
+  });
 });
diff --git a/src/components/SpeedLimiterView.tsx b/src/components/SpeedLimiterView.tsx
index fdf8307..9d81b23 100644
--- a/src/components/SpeedLimiterView.tsx
+++ b/src/components/SpeedLimiterView.tsx
@@ -8,12 +8,28 @@ type SpeedUnit = 'KB/s' | 'MB/s';
 
 const MAX_LIMIT_KIB = 10_485_760;
 const MAX_LIMIT_MB = 10240;
+const KIB_PER_MIB = 1024;
+
+export function speedValueToKiB(value: number, unit: SpeedUnit): number {
+  const numericValue = Number.isFinite(value) ? value : 1;
+  const valueKiB = unit === 'MB/s' ? numericValue * KIB_PER_MIB : numericValue;
+  return Math.max(1, Math.min(MAX_LIMIT_KIB, Math.round(valueKiB)));
+}
+
+export function speedValueFromKiB(valueKiB: number, unit: SpeedUnit): number {
+  const normalizedKiB = Math.max(1, Math.min(MAX_LIMIT_KIB, Math.round(valueKiB)));
+  return unit === 'MB/s' ? normalizedKiB / KIB_PER_MIB : normalizedKiB;
+}
+
+export function convertSpeedValue(value: number, fromUnit: SpeedUnit, toUnit: SpeedUnit): number {
+  return speedValueFromKiB(speedValueToKiB(value, fromUnit), toUnit);
+}
 
 export function parseLimit(limit: string, fallback: number): { value: number; unit: SpeedUnit } {
   const match = limit.trim().match(/^(\d+(?:\.\d+)?)\s*([km]?)b?(?:\/s)?$/i);
   const valueKiB = match
-    ? Math.max(1, Math.round(Number(match[1]) * (match[2].toLowerCase() === 'm' ? 1024 : 1)))
-    : fallback;
+    ? speedValueToKiB(Number(match[1]) * (match[2].toLowerCase() === 'm' ? KIB_PER_MIB : 1), 'KB/s')
+    : speedValueToKiB(fallback, 'KB/s');
 
   return valueKiB >= 1024 && valueKiB % 1024 === 0
     ? { value: valueKiB / 1024, unit: 'MB/s' }
@@ -24,17 +40,17 @@ function sanitizePresetValues(values: number[]): number[] {
   const cleaned = values
     .map(value => Number(value))
     .filter(value => Number.isFinite(value) && value > 0)
-    .map(value => Math.min(MAX_LIMIT_MB, Math.round(value * 100) / 100));
+    .map(value => speedValueFromKiB(speedValueToKiB(value, 'MB/s'), 'MB/s'));
 
   return Array.from(new Set(cleaned)).sort((a, b) => a - b);
 }
 
 export function presetBaseFromDisplayValue(value: number, unit: SpeedUnit): number {
-  return unit === 'MB/s' ? value : value / 1024;
+  return speedValueFromKiB(speedValueToKiB(value, unit), 'MB/s');
 }
 
 export function displayValueFromPresetBase(value: number, unit: SpeedUnit): number {
-  return unit === 'MB/s' ? value : Math.round(value * 1024);
+  return speedValueFromKiB(speedValueToKiB(value, 'MB/s'), unit);
 }
 
 function formatPresetValue(value: number): string {
@@ -75,7 +91,7 @@ export default function SpeedLimiterView() {
     if (savingRef.current) return;
     savingRef.current = true;
     const numericValue = Math.max(1, Math.min(Number(value) || 1, unit === 'MB/s' ? 10240 : MAX_LIMIT_KIB));
-    const valueKiB = Math.min(MAX_LIMIT_KIB, Math.round(unit === 'MB/s' ? numericValue * 1024 : numericValue));
+    const valueKiB = speedValueToKiB(numericValue, unit);
     setIsSaving(true);
     try {
       await setGlobalSpeedLimit(enabled ? `${valueKiB}K` : '');
@@ -127,6 +143,13 @@ export default function SpeedLimiterView() {
     });
   };
 
+  const changeUnit = (nextUnit: SpeedUnit) => {
+    if (nextUnit === unit) return;
+    setValue(convertSpeedValue(value, unit, nextUnit));
+    setCustomPresetValue(convertSpeedValue(customPresetValue, unit, nextUnit));
+    setUnit(nextUnit);
+  };
+
   return (
     <div className="flex-1 flex h-full flex-col overflow-hidden bg-main-bg">
       <WindowDragRegion />
@@ -169,6 +192,7 @@ export default function SpeedLimiterView() {
             <input
               type="number"
               min="1"
+              step="any"
               value={value}
               disabled={!enabled || isSaving}
               onChange={event => setValue(Math.max(1, Number(event.target.value) || 1))}
@@ -180,7 +204,7 @@ export default function SpeedLimiterView() {
                   key={option}
                   type="button"
                   disabled={!enabled || isSaving}
-                  onClick={() => setUnit(option)}
+                  onClick={() => changeUnit(option)}
                   className={`rounded px-3 py-1.5 text-[12px] font-medium ${
                     unit === option ? 'bg-accent text-white' : 'text-text-secondary hover:bg-item-hover'
                   }`}
@@ -228,6 +252,7 @@ export default function SpeedLimiterView() {
               <input
                 type="number"
                 min="1"
+                step="any"
                 value={customPresetValue}
                 disabled={!enabled || isSaving}
                 onChange={event => setCustomPresetValue(Math.max(1, Number(event.target.value) || 1))}