feat: sort-alpha button per group, settings in header, sortPosition pin

- ⇅ button on each group header: sorts units alpha (labelPlural + symbol tiebreak) via order API
- ⚙ Settings moved to admin-header alongside Log out
- Unit type gets sortPosition?: number (1-based, optional)
- Converter sort: partitions pinned/floating, inserts pins at requested slots
  Pins > length append at end; gaps fill naturally with floating items
- Admin unit form: Force position number input

data/units.json

@@ -7,7 +7,7 @@
       "symbol": "dl",
       "group": "dickloads",
       "toBase": 1,
-      "description": "See {pound:description}. Let's also look at {us-oil-bbl}."
+      "description": "The basic unit of measurement for all weights and masses worldwide."
     },
     {
       "id": "pound",
@@ -16,25 +16,26 @@
       "symbol": "lb",
       "group": "dickloads",
       "toBase": 0.038,
-      "description": "My description is {dickload:description}"
+      "description": "Avoirdupois pounds, as used in the USA."
     },
     {
       "id": "us-oil-bbl",
-      "label": "oil barrel (US)",
+      "label": "barrel",
-      "labelPlural": "oil barrels (US)",
+      "labelPlural": "barrels",
-      "symbol": "us oil bbl",
+      "symbol": "bbl us oil",
       "group": "dickloads",
       "toBase": 13.3192584,
       "description": "Weight is based on pure water at 4 degrees celsius.",
       "hidden": false
     },
     {
-      "id": "hogshead",
+      "id": "imperial-hogshead",
       "label": "hogshead",
       "labelPlural": "hogsheads",
-      "symbol": "hhd",
+      "symbol": "hhd imperial",
       "group": "dickloads",
-      "toBase": 38
+      "toBase": 27.420633296,
+      "description": "The hogshead as understood by residents of Old Blighty."
     },
     {
       "id": "short-ton",
@@ -108,26 +109,34 @@
       "id": "us-fluid-bbl",
       "label": "barrel",
       "labelPlural": "barrels",
-      "symbol": "us fluid bbl",
+      "symbol": "bbl us fluid",
       "group": "dickloads",
       "toBase": 9.9894438
     },
     {
       "id": "us-dry-bbl",
-      "label": "dry barrel",
+      "label": "barrel",
-      "labelPlural": "dry barrels",
+      "labelPlural": "barrels",
-      "symbol": "us dry bbl",
+      "symbol": "bbl us dry",
       "group": "dickloads",
-      "toBase": 1
+      "toBase": 9.6864954123
     },
     {
       "id": "us-hogshead",
-      "label": "hogshead (US)",
+      "label": "hogshead",
-      "labelPlural": "hogsheads (US)",
+      "labelPlural": "hogsheads",
-      "symbol": "us hhd",
+      "symbol": "hhd us",
       "group": "dickloads",
       "toBase": 19.9788876,
       "description": "Equal to two US fluid barrels."
+    },
+    {
+      "id": "imperial-barrel",
+      "label": "barrel",
+      "labelPlural": "barrels",
+      "symbol": "bbl imperial",
+      "group": "dickloads",
+      "toBase": 13.710316648
     }
   ],
   "groups": [

src/lib/types.ts

@@ -30,6 +30,14 @@ export interface Unit {
 
   /** If true, this unit is excluded from automatic rendering in the converter. */
   hidden?: boolean;
+
+  /**
+   * Optional fixed display position (1-based) within the group's rendered list.
+   * Pinned units are inserted at their requested slot after floating units are ordered.
+   * If position > total units, the unit is appended at the end in ascending sortPosition order.
+   * Ties are broken by the group's natural sort order.
+   */
+  sortPosition?: number;
 }
 
 /** A group of units sharing a base unit and a universal scale factor. */

src/routes/+page.svelte

@@ -152,13 +152,29 @@
     for (const group of groups) {
       const items = byGroup.get(group.id);
       if (items?.length) {
-        const sorted = group.sortOrder === 'alpha'
+        // Base order: alpha or defined
+        const base = group.sortOrder === 'alpha'
           ? [...items].sort((a, b) => {
               const labelCmp = a.unit.labelPlural.localeCompare(b.unit.labelPlural);
               return labelCmp !== 0 ? labelCmp : a.unit.symbol.localeCompare(b.unit.symbol);
             })
-          : items;
+          : [...items];
-        sections.push({ groupLabel: group.label, alwaysShowLabel: group.alwaysShowLabel ?? false, items: sorted });
+
+        // Partition into pinned (sortPosition set) and floating
+        const pinned = base.filter((r) => r.unit.sortPosition != null)
+          .sort((a, b) => (a.unit.sortPosition ?? 0) - (b.unit.sortPosition ?? 0));
+        const floating = base.filter((r) => r.unit.sortPosition == null);
+
+        // Insert pinned units at their requested 1-based positions
+        // Position > length → append at end in sortPosition order
+        const result: typeof base = [...floating];
+        for (const p of pinned) {
+          const pos = Math.max(1, p.unit.sortPosition ?? 1);
+          const insertAt = Math.min(pos - 1, result.length);
+          result.splice(insertAt, 0, p);
+        }
+
+        sections.push({ groupLabel: group.label, alwaysShowLabel: group.alwaysShowLabel ?? false, items: result });
       }
     }
     const orphaned = byGroup.get(null);

src/routes/admin/+page.svelte

@@ -638,6 +638,20 @@
     formError = null;
   }
 
+  async function sortGroupAlpha(group: Group) {
+    const units = unitsData.units.filter((u) => u.group === group.id);
+    const sorted = [...units].sort((a, b) => {
+      const cmp = a.labelPlural.localeCompare(b.labelPlural);
+      return cmp !== 0 ? cmp : a.symbol.localeCompare(b.symbol);
+    });
+    const res = await fetch(`${api}/order`, {
+      method: 'PUT',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ units: { [group.id]: sorted.map((u) => u.id) } })
+    });
+    if (res.ok) await loadData();
+  }
+
   function closeDeleteGroup() { deleteGroupTarget = null; }
 
   async function confirmDeleteGroup() {
@@ -683,7 +697,10 @@
 
 <div class="admin-header">
   <h2>Admin</h2>
-  <button class="outline secondary logout-btn" onclick={logout}>Log out</button>
+  <div class="admin-header-actions">
+    <button class="outline secondary" onclick={() => { selectedItem = { type: 'settings', id: 'settings' }; }}>⚙ Settings</button>
+    <button class="outline secondary logout-btn" onclick={logout}>Log out</button>
+  </div>
 </div>
 
 <div class="admin-panels">
@@ -800,6 +817,7 @@
           </button>
 
           <!-- Delete only — edit is via click on name -->
+          <button class="plain icon-btn" title="Sort alphabetically" onclick={() => sortGroupAlpha(group)}>⇅</button>
           <button class="plain icon-btn" title="Delete group" onclick={() => openDeleteGroup(group)}>🗑</button>
         </div>
 
@@ -900,7 +918,6 @@
     <div class="tree-footer">
       <button onclick={() => startNewUnit()}>+ Add Unit</button>
       <button class="outline" onclick={startNewGroup}>+ Add Group</button>
-      <button class="outline secondary" onclick={() => { selectedItem = { type: 'settings', id: 'settings' }; }}>⚙ Settings</button>
     </div>
   </aside>
 
@@ -960,6 +977,10 @@
         Description <small class="muted">(optional — shown as tooltip in converter)</small>
         <textarea bind:value={unitForm.description} placeholder="e.g. A unit based on…" rows="2"></textarea>
       </label>
+      <label>
+        Force position <small class="muted">(optional — pin this unit to a specific slot in the group)</small>
+        <input type="number" bind:value={unitForm.sortPosition} min="1" step="1" placeholder="e.g. 3" />
+      </label>
       <label class="checkbox-label">
         <input type="checkbox" bind:checked={unitForm.hidden} />
         <span>Don't show on front end</span>
@@ -1134,6 +1155,11 @@
     margin-bottom: 1.5rem;
   }
   .admin-header h2 { margin: 0; }
+  .admin-header-actions {
+    display: flex;
+    gap: 0.5rem;
+    align-items: center;
+  }
 
   .admin-panels {
     display: grid;