chore(vendor): import pi 1.3.0

Imported as a linear vendor commit so forge rebases do not replay the upstream root tree.

git-subtree-dir: third_party/pi

git-subtree-split: 71023aec1546d6d677a65669c5665c0927ce0dd0

third_party/pi/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 {
@@ -97,12 +97,29 @@ describe("Anthropic empty thinking signature compat", () => {
 		expect(assistant?.content).toEqual([{ type: "thinking", thinking: "internal reasoning", signature: "" }]);
 	});
 
-	it.each(["k3"] as const)("allows empty signatures for Kimi Coding %s", async (modelId) => {
-		const model = getModel("kimi-coding", modelId);
-		expect(model.compat?.allowEmptySignature).toBe(true);
+	// 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);
+	});
 
-		const payload = await capturePayload(model, makeContext(" ", "internal reasoning", "kimi-coding", modelId));
-		const assistant = payload.messages?.find((message) => message.role === "assistant");
-		expect(assistant?.content).toEqual([{ type: "thinking", thinking: "internal reasoning", signature: "" }]);
+	// Regression for #9323: Fireworks emits unsigned thinking that must survive replay.
+	it.each([
+		"accounts/fireworks/models/deepseek-v4p1-flash",
+		"accounts/fireworks/models/qwen3p8-max",
+		"accounts/fireworks/models/qwen3p8-2p4t-a95b",
+		"accounts/fireworks/models/nemotron-3-ultra-nvfp4",
+	] as const)("preserves unsigned thinking for Fireworks %s", async (modelId) => {
+		const model = getModel("fireworks", modelId);
+		expect(model.compat?.allowEmptySignature).toBe(true);
+		const context = makeContext("", "internal reasoning", "fireworks", modelId);
+		const assistant = context.messages[1] as AssistantMessage;
+		assistant.content.push({ type: "text", text: "answer" });
+		const payload = await capturePayload(model, context);
+		expect(payload.messages?.find((message) => message.role === "assistant")?.content).toEqual([
+			{ type: "thinking", thinking: "internal reasoning", signature: "" },
+			{ type: "text", text: "answer" },
+		]);
 	});
 });