refactor: scope postcode cache to place names, DB is authoritative for postcodes

app/Services/PostcodeService.php

@@ -26,7 +26,16 @@ class PostcodeService
     public function resolve(string $query): ?LocationResult
     {
         $query = trim($query);
-        $cacheKey = 'postcode:'.strtolower(preg_replace('/\s+/', '', $query));
+
+        if ($this->isFullPostcode($query)) {
+            return $this->lookupLocalPostcode($query) ?? $this->lookupPostcode($query);
+        }
+
+        if ($this->isOutcode($query)) {
+            return $this->lookupLocalOutcode($query) ?? $this->lookupOutcode($query);
+        }
+
+        $cacheKey = 'place:'.strtolower(preg_replace('/\s+/', '', $query));
 
         $cached = Cache::get($cacheKey);
 
@@ -34,11 +43,7 @@ class PostcodeService
             return $cached;
         }
 
-        $result = match (true) {
+        $result = $this->lookupPlace($query);
-            $this->isFullPostcode($query) => $this->lookupLocalPostcode($query) ?? $this->lookupPostcode($query),
-            $this->isOutcode($query) => $this->lookupLocalOutcode($query) ?? $this->lookupOutcode($query),
-            default => $this->lookupPlace($query),
-        };
 
         if ($result !== null) {
             Cache::put($cacheKey, $result, self::CACHE_TTL);

tests/Unit/Services/PostcodeServiceTest.php

@@ -134,23 +134,41 @@ it('returns null when place name yields no results', function (): void {
 
 // --- Caching ---
 
-it('caches a successful resolution for 30 days', function (): void {
+it('caches a successful place resolution for 30 days', function (): void {
     Http::fake([
-        '*/outcodes/PE7' => Http::response([
+        '*/places*' => Http::response([
+            'status' => 200,
+            'result' => [[
+                'name_1' => 'Manchester',
+                'latitude' => 53.480957,
+                'longitude' => -2.237428,
+            ]],
+        ]),
+    ]);
+
+    $this->service->resolve('Manchester');
+    $this->service->resolve('Manchester');
+
+    Http::assertSentCount(1);
+    expect(Cache::get('place:manchester'))->toBeInstanceOf(LocationResult::class);
+});
+
+it('does not cache postcode resolutions in the Cache store (DB is the cache)', function (): void {
+    Http::fake([
+        '*/postcodes/SW1A1AA' => Http::response([
             'status' => 200,
             'result' => [
-                'outcode' => 'PE7',
+                'postcode' => 'SW1A 1AA',
-                'latitude' => 52.536397,
+                'latitude' => 51.501009,
-                'longitude' => -0.210181,
+                'longitude' => -0.141588,
             ],
         ]),
     ]);
 
-    $this->service->resolve('PE7');
+    $this->service->resolve('SW1A 1AA');
-    $this->service->resolve('PE7');
 
-    Http::assertSentCount(1);
+    expect(Cache::get('postcode:sw1a1aa'))->toBeNull()
-    expect(Cache::get('postcode:pe7'))->toBeInstanceOf(LocationResult::class);
+        ->and(Postcode::find('SW1A1AA'))->not->toBeNull();
 });
 
 it('does not cache failed lookups', function (): void {