Add warning for smart placement

packages/wrangler/src/__tests__/deploy.test.ts

@@ -4446,6 +4446,47 @@ addEventListener('fetch', event => {});`
 			`);
 		});
 
+		it("should warn when using smart placement with Worker first", async () => {
+			const assets = [
+				{ filePath: ".assetsignore", content: "*.bak\nsub-dir" },
+				{ filePath: "file-1.txt", content: "Content of file-1" },
+				{ filePath: "file-2.bak", content: "Content of file-2" },
+				{ filePath: "file-3.txt", content: "Content of file-3" },
+				{ filePath: "sub-dir/file-4.bak", content: "Content of file-4" },
+				{ filePath: "sub-dir/file-5.txt", content: "Content of file-5" },
+			];
+			writeAssets(assets, "assets");
+			writeWranglerConfig({
+				assets: {
+					directory: "assets",
+					experimental_serve_directly: false,
+				},
+				placement: {
+					mode: "smart",
+				},
+			});
+			const bodies: AssetManifest[] = [];
+			await mockAUSRequest(bodies);
+			mockSubDomainRequest();
+			mockUploadWorkerRequest({
+				expectedAssets: {
+					jwt: "<<aus-completion-token>>",
+					config: {
+						serve_directly: true,
+					},
+				},
+				expectedType: "none",
+			});
+
+			await runWrangler("deploy");
+
+			expect(std.warn).toMatchInlineSnapshot(`
+				"▲ [WARNING] Using assets with smart placement enabled may result in poor performance.
+
+				"
+			`);
+		});
+
 		it("should warn if experimental_serve_directly=false but no binding is provided", async () => {
 			const assets = [
 				{ filePath: ".assetsignore", content: "*.bak\nsub-dir" },

packages/wrangler/src/assets.ts

@@ -444,6 +444,16 @@ export function validateAssetsArgsAndConfig(
 		);
 	}
 
+	// Smart placement turned on when using assets
+	if (
+		config?.placement?.mode === "smart" &&
+		config?.assets?.experimental_serve_directly === false
+	) {
+		logger.warn(
+			"Using assets with smart placement enabled may result in poor performance."
+		);
+	}
+
 	// User Worker ahead of assets, but no assets binding provided
 	if (
 		"legacy" in args