Add category filters and live search to parts page

- Filter chips for in-use categories with OR semantics; "All" chip shown
  when nothing is selected.
- Search input filters as the user types (150 ms debounce, replaceState
  so back-button stays useful).
- Fix sort indicators: the `arrow()` helper read `sort`/`dir` from a
  plain function, which Svelte's static dep tracking doesn't trace —
  the ▲/▼ never updated on client-side sorts. Made it a reactive `$:`
  declaration.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/i18n/en.json

@@ -68,6 +68,7 @@
     "active": "Active",
     "search_placeholder": "Search by SKU, name, or barcode…",
     "no_results": "No parts match your search.",
+    "all": "All",
     "recent_movements": "Recent movements",
     "initial_quantity": "Initial quantity",
     "errors": {

src/lib/i18n/tg.json

@@ -68,6 +68,7 @@
     "active": "Фаъол",
     "search_placeholder": "Ҷустуҷӯ аз рӯи SKU, ном ё штрих-код…",
     "no_results": "Ҳеҷ қисм мувофиқат намекунад.",
+    "all": "Ҳама",
     "recent_movements": "Ҳаракатҳои охирин",
     "initial_quantity": "Шумораи аввала",
     "errors": {

src/lib/server/parts.js

@@ -6,7 +6,7 @@ const SORTABLE = new Set([
   'sale_price', 'cost_price', 'reorder_level', 'updated_at'
 ]);
 
-export function listParts({ q = '', sort = 'sku', dir = 'asc' } = {}) {
+export function listParts({ q = '', sort = 'sku', dir = 'asc', categoryIds = [] } = {}) {
   const db = getDb();
   const col = SORTABLE.has(sort) ? sort : 'sku';
   const order = dir === 'desc' ? 'DESC' : 'ASC';
@@ -17,6 +17,11 @@ export function listParts({ q = '', sort = 'sku', dir = 'asc' } = {}) {
     where.push(`(p.sku LIKE @q OR p.name_en LIKE @q OR p.name_tg LIKE @q OR p.barcode LIKE @q)`);
     params.q = `%${q.trim()}%`;
   }
+  if (categoryIds && categoryIds.length) {
+    const placeholders = categoryIds.map((_, i) => `@cat${i}`).join(',');
+    where.push(`p.category_id IN (${placeholders})`);
+    categoryIds.forEach((id, i) => { params[`cat${i}`] = id; });
+  }
   const whereSql = where.length ? `WHERE ${where.join(' AND ')}` : '';
 
   const sql = `
@@ -48,6 +53,17 @@ export function listCategories() {
     .all();
 }
 
+// Categories that have at least one part — used to build the filter chips on
+// the parts list so we don't offer empty options.
+export function categoriesWithParts() {
+  return getDb().prepare(`
+    SELECT c.* FROM categories c
+    JOIN parts p ON p.category_id = c.id
+    GROUP BY c.id
+    ORDER BY c.sort_order, c.name_en
+  `).all();
+}
+
 export function createPart(input) {
   const db = getDb();
   const stmt = db.prepare(`

src/routes/parts/+page.server.js

@@ -1,8 +1,17 @@
-import { listParts } from '$lib/server/parts.js';
+import { listParts, categoriesWithParts } from '$lib/server/parts.js';
 
 export function load({ url }) {
   const q    = url.searchParams.get('q')    ?? '';
   const sort = url.searchParams.get('sort') ?? 'sku';
   const dir  = url.searchParams.get('dir')  ?? 'asc';
-  return { parts: listParts({ q, sort, dir }), q, sort, dir };
+  const cat  = url.searchParams.get('category') ?? '';
+  const categoryIds = cat
+    .split(',')
+    .map((s) => Number(s))
+    .filter((n) => Number.isInteger(n) && n > 0);
+  return {
+    parts: listParts({ q, sort, dir, categoryIds }),
+    categories: categoriesWithParts(),
+    q, sort, dir, categoryIds,
+  };
 }

src/routes/parts/+page.svelte

@@ -4,33 +4,55 @@
 
   export let data;
   $: lang = $locale;
-  $: ({ parts, q, sort, dir } = data);
+  $: ({ parts, categories, q, sort, dir, categoryIds } = data);
 
   let search = data.q;
+  let searchTimer = null;
 
-  function applySearch(e) {
-    e?.preventDefault?.();
+  $: selectedSet = new Set(categoryIds);
+
+  function navigate({ qNext = search, sortNext = sort, dirNext = dir, catsNext = categoryIds } = {}) {
     const params = new URLSearchParams();
-    if (search) params.set('q', search);
-    if (sort && sort !== 'sku') params.set('sort', sort);
-    if (dir && dir !== 'asc') params.set('dir', dir);
-    goto('/parts' + (params.toString() ? '?' + params.toString() : ''));
+    if (qNext) params.set('q', qNext);
+    if (catsNext.length) params.set('category', catsNext.join(','));
+    if (sortNext && sortNext !== 'sku') params.set('sort', sortNext);
+    if (dirNext && dirNext !== 'asc') params.set('dir', dirNext);
+    const target = '/parts' + (params.toString() ? '?' + params.toString() : '');
+    goto(target, { replaceState: true, keepFocus: true, noScroll: true });
+  }
+
+  function onSearchInput() {
+    clearTimeout(searchTimer);
+    searchTimer = setTimeout(() => navigate({ qNext: search }), 150);
+  }
+
+  function clearSearch() {
+    clearTimeout(searchTimer);
+    search = '';
+    navigate({ qNext: '' });
+  }
+
+  function toggleCategory(id) {
+    const next = selectedSet.has(id)
+      ? categoryIds.filter((c) => c !== id)
+      : [...categoryIds, id];
+    navigate({ catsNext: next });
+  }
+
+  function clearCategories() {
+    navigate({ catsNext: [] });
   }
 
   function sortBy(col) {
     let nextDir = 'asc';
     if (sort === col && dir === 'asc') nextDir = 'desc';
-    const params = new URLSearchParams();
-    if (search) params.set('q', search);
-    params.set('sort', col);
-    params.set('dir', nextDir);
-    goto('/parts?' + params.toString());
+    navigate({ sortNext: col, dirNext: nextDir });
   }
 
-  function arrow(col) {
-    if (sort !== col) return '';
-    return dir === 'asc' ? '▲' : '▼';
-  }
+  // Reactive so the header indicators refresh when `sort` / `dir` change.
+  // A plain function declaration wouldn't — Svelte tracks reactive deps via
+  // static analysis and doesn't look inside function bodies.
+  $: arrow = (col) => (sort === col ? (dir === 'asc' ? '▲' : '▼') : '');
 </script>
 
 <div class="page-head">
@@ -38,18 +60,38 @@
   <a class="add-btn" href="/parts/new">+ {$t('nav.new_part')}</a>
 </div>
 
-<form class="search" on:submit={applySearch}>
+<div class="search">
   <input type="search"
          bind:value={search}
+         on:input={onSearchInput}
          placeholder={$t('parts.search_placeholder')} />
-  <button type="submit">{$t('common.search')}</button>
   {#if search}
-    <button type="button" class="secondary"
-      on:click={() => { search = ''; applySearch(); }}>
+    <button type="button" class="secondary" on:click={clearSearch}>
       {$t('common.clear')}
     </button>
   {/if}
-</form>
+</div>
+
+{#if categories.length > 0}
+  <div class="filters" role="group" aria-label={$t('parts.category')}>
+    <button type="button"
+            class="chip"
+            class:active={categoryIds.length === 0}
+            aria-pressed={categoryIds.length === 0}
+            on:click={clearCategories}>
+      {$t('parts.all')}
+    </button>
+    {#each categories as c}
+      <button type="button"
+              class="chip"
+              class:active={selectedSet.has(c.id)}
+              aria-pressed={selectedSet.has(c.id)}
+              on:click={() => toggleCategory(c.id)}>
+        {localized(c, 'name', lang)}
+      </button>
+    {/each}
+  </div>
+{/if}
 
 {#if parts.length === 0}
   <p class="muted card">{$t('parts.no_results')}</p>
@@ -104,9 +146,34 @@
   .search {
     display: flex;
     gap: 0.5rem;
-    margin: 0.5rem 0 1rem;
+    margin: 0.5rem 0 0.75rem;
   }
   .search input { flex: 1; }
+  .filters {
+    display: flex;
+    flex-wrap: wrap;
+    gap: 0.4rem;
+    margin: 0 0 1rem;
+  }
+  .chip {
+    background: #fff;
+    color: #1d2330;
+    border: 1px solid #c8cfdc;
+    padding: 0.3rem 0.75rem;
+    border-radius: 999px;
+    font-size: 0.85rem;
+    font-weight: 500;
+    line-height: 1.2;
+    cursor: pointer;
+    transition: background 0.1s, border-color 0.1s, color 0.1s;
+  }
+  .chip:hover { background: #f0f2f6; }
+  .chip.active {
+    background: #006a4e;
+    color: #fff;
+    border-color: #006a4e;
+  }
+  .chip.active:hover { background: #00553e; border-color: #00553e; }
   .th-btn {
     background: transparent;
     color: inherit;