feat: YOLO toggle inline layout; yoloLabel/yoloDescription configurable via config.json

src/components/UnitInput.svelte

@@ -1,16 +1,6 @@
 <script lang="ts">
   /**
-   * UnitInput — uncontrolled numeric input with one-way push to parent.
-   *
-   * The input owns its own DOM value. We only push changes upward via onchange.
-   * We deliberately do NOT set value={value} on the input element — that would
-   * cause Svelte to re-render the input on every parent state update, resetting
-   * the cursor position and stealing focus mid-typing.
-   *
-   * The parent can pass a new `value` prop if it needs to imperatively set the
-   * input (e.g. Ctrl+click adopts a converted value). We detect that via $effect
-   * and update the DOM node directly, only when the value actually differs from
-   * what's currently in the input.
+   * UnitInput — controlled numeric input.
    */
 
   let {
@@ -21,18 +11,6 @@
     onchange: (v: number) => void;
   } = $props();
 
-  let inputEl = $state<HTMLInputElement | null>(null);
-
-  // Sync parent-driven value changes into the DOM — but only when the parent
-  // is actually setting a new value (e.g. Ctrl+click), not on every keystroke.
-  $effect(() => {
-    if (!inputEl) return;
-    const current = parseFloat(inputEl.value);
-    if (isNaN(current) || current !== value) {
-      inputEl.value = String(value);
-    }
-  });
-
   function handleInput(e: Event) {
     const input = e.currentTarget as HTMLInputElement;
     const parsed = parseFloat(input.value);
@@ -43,9 +21,9 @@
 </script>
 
 <input
-  bind:this={inputEl}
   type="number"
   step="any"
+  value={value}
   oninput={handleInput}
   aria-label="Input value"
 />

src/lib/server/data.ts

@@ -11,6 +11,10 @@ export interface AppConfig {
   adminPath: string;
   passwordHash: string;
   sessionSecret: string;
+  /** Label shown next to the YOLO mode toggle. Defaults to "YOLO mode". */
+  yoloLabel?: string;
+  /** Description shown inline after the label. Defaults to "(cross-group conversions)". */
+  yoloDescription?: string;
 }
 
 /** Read units.json synchronously. Returns parsed UnitsData. */

src/routes/+page.server.ts

@@ -1,10 +1,13 @@
-import { loadData } from '$lib/server/data';
+import { loadData, loadConfig } from '$lib/server/data';
 import type { PageServerLoad } from './$types';
 
 export const load: PageServerLoad = () => {
   const data = loadData();
+  const config = loadConfig();
   return {
     units: data.units,
-    groups: data.groups
+    groups: data.groups,
+    yoloLabel: config.yoloLabel ?? 'YOLO mode',
+    yoloDescription: config.yoloDescription ?? '(cross-group conversions)'
   };
 };

src/routes/+page.svelte

@@ -14,10 +14,12 @@
    * Supports same-group and cross-group (YOLO) conversions.
    */
 
-  let { data }: { data: { units: Unit[]; groups: Group[] } } = $props();
+  let { data }: { data: { units: Unit[]; groups: Group[]; yoloLabel: string; yoloDescription: string } } = $props();
 
   let units: Unit[] = $derived(data.units);
   let groups: Group[] = $derived(data.groups);
+  let yoloLabel: string = $derived(data.yoloLabel);
+  let yoloDescription: string = $derived(data.yoloDescription);
 
   // ── Reactive state ──────────────────────────────────────────────────────────
   let inputValue = $state<number>(1);
@@ -94,6 +96,8 @@
   );
 
   // ── URL sync ────────────────────────────────────────────────────────────────
+  // Use history.replaceState directly — goto() triggers a SvelteKit navigation
+  // which re-renders the page and steals focus from the input on every keystroke.
   $effect(() => {
     if (!browser) return;
     const params = new URLSearchParams();
@@ -104,7 +108,7 @@
     }
     const next = params.toString();
     if (next !== window.location.search.slice(1)) {
-      goto(`?${next}`, { replaceState: true, noScroll: true });
+      history.replaceState(history.state, '', `?${next}`);
     }
   });
 
@@ -176,7 +180,10 @@
 <div class="yolo-toggle-row">
   <label class="yolo-label">
     <input type="checkbox" bind:checked={yoloMode} role="switch" />
-    YOLO mode <small>(cross-group conversions)</small>
+    <span class="yolo-label-text">{yoloLabel}</span>
+    {#if yoloDescription}
+      <small class="yolo-desc">{yoloDescription}</small>
+    {/if}
   </label>
 </div>
 
@@ -198,17 +205,24 @@
 <style>
   .yolo-toggle-row {
     margin-bottom: 1rem;
-    display: flex;
-    align-items: center;
-    gap: 0.5rem;
   }
 
   .yolo-label {
-    display: flex;
+    display: inline-flex;
     align-items: center;
     gap: 0.5rem;
     cursor: pointer;
     user-select: none;
+    white-space: nowrap;
+  }
+
+  .yolo-label-text {
+    font-weight: 500;
+  }
+
+  .yolo-desc {
+    color: var(--pico-muted-color);
+    white-space: nowrap;
   }
 
   .yolo-marker {