Fix PR #689: Add changelog attribution, coding-agent changelog, fix test types, add provider to test suites

- Fix ai/CHANGELOG.md: add PR link and author attribution
- Add coding-agent/CHANGELOG.md entry for vercel-ai-gateway provider
- Fix model-resolver.test.ts: use anthropic-messages API type to match generated models
- Add vercel-ai-gateway to test suites: tokens, abort, empty, context-overflow, unicode-surrogate, tool-call-without-result, image-tool-result, total-tokens, image-limits

packages/ai/test/total-tokens.test.ts

@@ -348,6 +348,29 @@ describe("totalTokens field", () => {
 		);
 	});
 
+	// =========================================================================
+	// Vercel AI Gateway
+	// =========================================================================
+
+	describe.skipIf(!process.env.AI_GATEWAY_API_KEY)("Vercel AI Gateway", () => {
+		it(
+			"google/gemini-2.5-flash - should return totalTokens equal to sum of components",
+			{ retry: 3, timeout: 60000 },
+			async () => {
+				const llm = getModel("vercel-ai-gateway", "google/gemini-2.5-flash");
+
+				console.log(`\nVercel AI Gateway / ${llm.id}:`);
+				const { first, second } = await testTotalTokensWithCache(llm, { apiKey: process.env.AI_GATEWAY_API_KEY });
+
+				logUsage("First request", first);
+				logUsage("Second request", second);
+
+				assertTotalTokensEqualsComponents(first);
+				assertTotalTokensEqualsComponents(second);
+			},
+		);
+	});
+
 	// =========================================================================
 	// OpenRouter - Multiple backend providers
 	// =========================================================================