diff --git a/src/ad_seller/services/catalog_service.py b/src/ad_seller/services/catalog_service.py
index 06a80c3..c6dd60d 100644
--- a/src/ad_seller/services/catalog_service.py
+++ b/src/ad_seller/services/catalog_service.py
@@ -392,11 +392,15 @@ def build_static_product_catalog() -> dict[str, Any]:
     """Build a fresh catalog dict from ``DEFAULT_PRODUCT_CONFIGS`` (uncached).
 
     Returns ``{"products": {product_id: ProductDefinition}, "inventory_types": [...]}``
-    with newly generated product IDs.
+    with deterministic product IDs derived from each config's name, so every
+    process (and every uvicorn worker) serves the same ids. Random per-process
+    ids meant a list-then-get across two workers, or across a restart, could
+    404 on an id the server itself had just returned (issue #34).
     """
     products: dict[str, Any] = {}
     for cfg in DEFAULT_PRODUCT_CONFIGS:
-        product_def = product_from_config(cfg, f"prod-{uuid.uuid4().hex[:8]}")
+        stable = uuid.uuid5(uuid.NAMESPACE_URL, f"ad-seller-product:{cfg['name']}")
+        product_def = product_from_config(cfg, f"prod-{stable.hex[:8]}")
         products[product_def.product_id] = product_def
 
     inventory_types = sorted({p.inventory_type for p in products.values()})
diff --git a/tests/unit/test_csv_catalog_coherence.py b/tests/unit/test_csv_catalog_coherence.py
index 3a5aa5b..53fed0c 100644
--- a/tests/unit/test_csv_catalog_coherence.py
+++ b/tests/unit/test_csv_catalog_coherence.py
@@ -215,6 +215,16 @@ def test_default_mode_ids_stay_uuid_shaped_and_stable(self, default_mode):
         second = catalog_service.get_static_product_catalog()
         assert list(first["products"].keys()) == list(second["products"].keys())
 
+    def test_default_mode_ids_survive_cache_reset(self, default_mode):
+        # Proxy for multi-worker and restart behavior (issue #34): each uvicorn
+        # worker builds its own catalog cache, so ids must be deterministic
+        # across independent builds, not merely stable within one cache.
+        first = catalog_service.get_static_product_catalog()
+        catalog_service.reset_catalog_cache()
+        second = catalog_service.get_static_product_catalog()
+        assert list(first["products"].keys()) == list(second["products"].keys())
+        assert len(set(first["products"])) == len(catalog_service.DEFAULT_PRODUCT_CONFIGS)
+
 
 # =============================================================================
 # API surface — CSV mode