diff --git a/packages/ai/CHANGELOG.md b/packages/ai/CHANGELOG.md
index 00fefb699..44d4e5284 100644
--- a/packages/ai/CHANGELOG.md
+++ b/packages/ai/CHANGELOG.md
@@ -9,6 +9,7 @@
 
 ### Fixed
 
+- Fixed Vercel AI Gateway replaying unsigned thinking as assistant text ([#9676](https://github.com/earendil-works/pi/issues/9676)).
 - Fixed Google Generative AI and Vertex AI using unsupported thinking levels when reasoning is omitted or when model capabilities differ within a Gemini family ([#9455](https://github.com/earendil-works/pi/issues/9455)).
 - Fixed Anthropic-compatible relays breaking signed thinking replay when they report a different response model, while preserving fallback pricing ([#9188](https://github.com/earendil-works/pi/issues/9188)).
 - Fixed Amazon Bedrock one-hour cache writes being priced at the five-minute rate ([#9457](https://github.com/earendil-works/pi/issues/9457)).
diff --git a/packages/ai/scripts/generate-models.ts b/packages/ai/scripts/generate-models.ts
index da85a69b8..b1dfcf10f 100644
--- a/packages/ai/scripts/generate-models.ts
+++ b/packages/ai/scripts/generate-models.ts
@@ -1306,6 +1306,7 @@ async function fetchAiGatewayModels(): Promise<Model<any>[]> {
 				provider: "vercel-ai-gateway",
 				reasoning: tags.includes("reasoning"),
 				input,
+				compat: { allowEmptySignature: true },
 				cost: {
 					input: inputCost,
 					output: outputCost,
diff --git a/packages/ai/test/anthropic-empty-thinking-signature-compat.test.ts b/packages/ai/test/anthropic-empty-thinking-signature-compat.test.ts
index 8f393ac57..4811e895d 100644
--- a/packages/ai/test/anthropic-empty-thinking-signature-compat.test.ts
+++ b/packages/ai/test/anthropic-empty-thinking-signature-compat.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { getModel, streamSimple } from "../src/compat.ts";
+import { getModel, getModels, streamSimple } from "../src/compat.ts";
 import type { AssistantMessage, Context, Model } from "../src/types.ts";
 
 interface AnthropicPayload {
@@ -97,6 +97,13 @@ describe("Anthropic empty thinking signature compat", () => {
 		expect(assistant?.content).toEqual([{ type: "thinking", thinking: "internal reasoning", signature: "" }]);
 	});
 
+	// Regression for #9676: Vercel AI Gateway emits unsigned thinking for translated models.
+	it("allows empty thinking signatures for every Vercel AI Gateway model", () => {
+		const models = getModels("vercel-ai-gateway");
+		expect(models.length).toBeGreaterThan(0);
+		expect(models.every((model) => model.compat?.allowEmptySignature === true)).toBe(true);
+	});
+
 	// Regression for #9323: Fireworks emits unsigned thinking that must survive replay.
 	it.each([
 		"accounts/fireworks/models/deepseek-v4-flash-0731",