fix: clear price to null when a comparison finds no merchant offer

Several memory sticks (e.g. Crucial CT8G48C40U5, Patriot Signature Line,
Kingston FURY Beast) kept displaying their pc-builder.io catalog price
("€35.99", "€39.99"...) even after clicking "Compare prices" and getting
"No live price found, using catalog price" - an unconfirmed number was
being shown as if it were still valid, which is misleading given
pc-builder.io's catalog is known to go stale (see the earlier RTX 5070
€128 vs €66.89 case).

New clearPriceIfNoOffers(): when ScrapedPartsController#compare finds
zero offers across all 7 supported merchants, the part's price/priceSource
are reset to null, regardless of whether the price previously came from
the pc-builder.io catalog or an earlier verified merchant match - per
explicit product decision, an empty comparison always wins over keeping a
possibly-stale number around.

- ScrapedPartsController#compare now calls clearPriceIfNoOffers() in the
  empty-offers branch, and returns the resulting price in the JSON
  response so the frontend can mirror it exactly
- NewPartSearch.vue: comparePrices() now sets part.price from the
  response's `price` field (mirroring exactly what the backend just
  persisted) instead of only updating it on a cheaper find; removed the
  now-inaccurate "using catalog price €X" message since that price no
  longer exists once compared with no result
- 3 new tests for clearPriceIfNoOffers: clears an unverified
  pc-builder.io price, also clears a previously-verified merchant price
  when no longer confirmed, and is a no-op when there was no price to
  begin with

Verified end-to-end against the reported Crucial CT8G48C40U5 example:
price went from 35.99 (pc-builder.io) to null after a real comparison
found zero matching offers on any merchant.

app/controllers/scraped_parts_controller.ts

@@ -2,7 +2,11 @@ import type { HttpContext } from '@adonisjs/core/http'
 import vine from '@vinejs/vine'
 import ScrapedPart from '#models/scraped_part'
 import ComponentType from '#models/component_type'
-import { ensureFreshCategory, updatePriceIfCheaper } from '#services/part_scraper_service'
+import {
+  ensureFreshCategory,
+  updatePriceIfCheaper,
+  clearPriceIfNoOffers,
+} from '#services/part_scraper_service'
 import { findCheapestOffers } from '#services/merchant_price_service'
 
 const SEARCH_RESULTS_LIMIT = 150
@@ -76,6 +80,11 @@ export default class ScrapedPartsController {
    * (or no price was known yet), it's persisted as the new default price
    * (see updatePriceIfCheaper) — so this comparison benefits every future
    * search/import for this part, not just the current user.
+   *
+   * If NO merchant confirms a price at all, the part's price is cleared
+   * to null (see clearPriceIfNoOffers) rather than silently keeping a
+   * pc-builder.io catalog price the user just explicitly asked to verify
+   * and that no longer checks out anywhere.
    */
   async compare({ request, auth, response }: HttpContext) {
     await auth.authenticate()
@@ -91,8 +100,10 @@ export default class ScrapedPartsController {
 
     if (offers.length > 0) {
       await updatePriceIfCheaper(part, offers[0])
+    } else {
+      await clearPriceIfNoOffers(part)
     }
 
-    return response.json({ offers })
+    return response.json({ offers, price: part.price })
   }
 }

app/services/part_scraper_service.ts

@@ -415,12 +415,34 @@ async function updatePriceIfCheaper(
   await part.save()
 }
 
+/**
+ * Clears a part's price when a live comparison found no matching offer on
+ * any supported merchant (see ScrapedPartsController#compare), regardless
+ * of where the price previously came from (pc-builder.io catalog or an
+ * earlier verified merchant match). The pc-builder.io catalog price this
+ * part started with is frequently stale (see shouldKeepExistingPrice's
+ * doc for a confirmed example: pc-builder.io showed €128 for a CPU
+ * actually selling for €66.89) — once a user explicitly asks to verify a
+ * price and no merchant confirms it anymore, keeping the old number
+ * around is misleading, so it's dropped to null instead of silently
+ * falling back to "using catalog price €X".
+ */
+async function clearPriceIfNoOffers(part: ScrapedPart): Promise<void> {
+  if (part.price === null) return
+
+  part.price = null
+  part.priceSource = null
+  part.priceCheckedAt = DateTime.now()
+  await part.save()
+}
+
 export {
   scrapeAllCategories,
   scrapeComponentType,
   ensureFreshCategory,
   isCategoryStale,
   updatePriceIfCheaper,
+  clearPriceIfNoOffers,
   shouldKeepExistingPrice,
   CATEGORY_CONFIG,
   CATEGORY_SLUGS,

inertia/pages/widgets/NewPartSearch.vue

@@ -62,21 +62,20 @@ async function comparePrices(part: ScrapedPart) {
     }
     const data = await response.json()
     offers[part.id] = data.offers ?? []
+
+    // The backend already persists this exact value server-side (see
+    // ScrapedPartsController#compare): the cheapest offer's price when
+    // one was found (updatePriceIfCheaper), or null when no merchant
+    // confirmed a price at all (clearPriceIfNoOffers) — an unverified
+    // pc-builder.io catalog price is not kept around just because the
+    // comparison came back empty. Mirror that here on the locally held
+    // result so the display (e.g. "€979.95" or "No price yet") reflects
+    // it immediately, instead of the initial search-result price sticking
+    // around until the user re-runs the search from scratch.
+    part.price = data.price ?? null
+
     if (offers[part.id].length === 0) {
       compareErrors[part.id] = true
-      return
-    }
-
-    // The backend already persists the cheapest offer found as this
-    // part's new best-known price when it beats the catalog price (see
-    // ScrapedPartsController#compare / updatePriceIfCheaper). Mirror that
-    // here on the locally held result so the displayed catalog price
-    // (e.g. "€979.95") reflects it immediately, instead of staying stuck
-    // at whatever price the initial search returned until the user
-    // re-runs the search from scratch.
-    const cheapest = offers[part.id][0]
-    if (part.price === null || cheapest.price < part.price) {
-      part.price = cheapest.price
     }
   } catch {
     compareErrors[part.id] = true
@@ -185,10 +184,7 @@ function importPart(part: ScrapedPart) {
             </a>
           </template>
 
-          <span v-if="compareErrors[part.id] && part.price !== null" class="text-xs text-gray-400">
-            No live price found, using catalog price €{{ part.price.toFixed(2) }}
-          </span>
-          <span v-else-if="compareErrors[part.id]" class="text-xs text-gray-400">
+          <span v-if="compareErrors[part.id]" class="text-xs text-gray-400">
             No price found on any merchant for this part.
           </span>
         </div>

tests/functional/scraped_parts.spec.ts

@@ -7,6 +7,7 @@ import {
   isCategoryStale,
   ensureFreshCategory,
   updatePriceIfCheaper,
+  clearPriceIfNoOffers,
   shouldKeepExistingPrice,
   CACHE_TTL_HOURS,
 } from '#services/part_scraper_service'
@@ -217,6 +218,53 @@ test.group('Best-known-price persistence', () => {
   })
 })
 
+test.group('clearPriceIfNoOffers', () => {
+  test('clears an unverified pc-builder.io catalog price when no merchant confirms it', async ({
+    assert,
+  }) => {
+    // Regression: memory sticks kept showing pc-builder.io catalog prices
+    // (e.g. €35.99) even though comparing prices found no matching offer
+    // on any merchant ("No live price found, using catalog price €35.99")
+    // — an unconfirmed number should not be displayed as if it were still
+    // valid.
+    const type = await createType('Memory-clear-1')
+    const part = await createScrapedPart(type.id, 'ZZZ-Test-Clear-A', 'clear-a-p1', 35.99)
+
+    await clearPriceIfNoOffers(part)
+    await part.refresh()
+
+    assert.isNull(part.price)
+    assert.isNull(part.priceSource)
+  })
+
+  test('also clears a price previously verified by a merchant if no longer confirmed', async ({
+    assert,
+  }) => {
+    const type = await createType('Memory-clear-2')
+    const part = await createScrapedPart(type.id, 'ZZZ-Test-Clear-B', 'clear-b-p1', 50)
+    part.priceSource = 'LDLC'
+    await part.save()
+
+    await clearPriceIfNoOffers(part)
+    await part.refresh()
+
+    assert.isNull(part.price)
+    assert.isNull(part.priceSource)
+  })
+
+  test('is a no-op when the part already has no price', async ({ assert }) => {
+    const type = await createType('Memory-clear-3')
+    const part = await createScrapedPart(type.id, 'ZZZ-Test-Clear-C', 'clear-c-p1', null)
+    const originalCheckedAt = part.priceCheckedAt
+
+    await clearPriceIfNoOffers(part)
+    await part.refresh()
+
+    assert.isNull(part.price)
+    assert.equal(part.priceCheckedAt, originalCheckedAt)
+  })
+})
+
 test.group('Catalog refresh price protection (shouldKeepExistingPrice)', () => {
   test('an unverified pc-builder.io price is NOT protected and gets overwritten', ({ assert }) => {
     // Regression test: a GPU had price=431.17 from a previous pc-builder.io