diff --git a/src/plugin-sdk/provider-catalog-shared.test.ts b/src/plugin-sdk/provider-catalog-shared.test.ts
index bcb29e8d9d0..1a39fcfc56a 100644
--- a/src/plugin-sdk/provider-catalog-shared.test.ts
+++ b/src/plugin-sdk/provider-catalog-shared.test.ts
@@ -217,4 +217,27 @@ describe("provider-catalog-shared manifest provider configs", () => {
       }),
     ).toThrow("unsupported runtime input document");
   });
+
+  it("rejects manifest catalogs when normalization drops a model row", () => {
+    expect(() =>
+      buildManifestModelProviderConfig({
+        providerId: "example",
+        catalog: {
+          baseUrl: "https://api.example.test/v1",
+          models: [
+            {
+              id: "valid",
+              contextWindow: 1024,
+              maxTokens: 1024,
+            },
+            {
+              id: "",
+              contextWindow: 1024,
+              maxTokens: 1024,
+            },
+          ],
+        },
+      }),
+    ).toThrow("providers.example.models");
+  });
 });
diff --git a/src/plugin-sdk/provider-catalog-shared.ts b/src/plugin-sdk/provider-catalog-shared.ts
index 97e6b0a6e0d..850178720e6 100644
--- a/src/plugin-sdk/provider-catalog-shared.ts
+++ b/src/plugin-sdk/provider-catalog-shared.ts
@@ -32,6 +32,14 @@ export type ConfiguredProviderCatalogEntry = {
   input?: Array<"text" | "image" | "audio" | "video" | "document">;
 };
 
+function countRawManifestCatalogModels(catalog: unknown): number | undefined {
+  if (!catalog || typeof catalog !== "object") {
+    return undefined;
+  }
+  const models = (catalog as { models?: unknown }).models;
+  return Array.isArray(models) ? models.length : undefined;
+}
+
 function cloneManifestCatalogTieredCost(
   tier: ModelCatalogTieredCost,
 ): NonNullable<ModelDefinitionConfig["cost"]["tieredPricing"]>[number] {
@@ -102,6 +110,10 @@ export function buildManifestModelProviderConfig(params: {
   if (!catalog.baseUrl) {
     throw new Error(`Missing modelCatalog.providers.${params.providerId}.baseUrl`);
   }
+  const rawModelCount = countRawManifestCatalogModels(params.catalog);
+  if (rawModelCount !== undefined && rawModelCount !== catalog.models.length) {
+    throw new Error(`Invalid modelCatalog.providers.${params.providerId}.models`);
+  }
   return {
     baseUrl: catalog.baseUrl,
     ...(catalog.api ? { api: catalog.api } : {}),