chore(vendor): import pi 0.85.1

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: d981de1229ef899957bbe968bc8dcda02a21f477

third_party/pi/packages/coding-agent/test/suite/regressions/5998-blocked-tool-terminate.test.ts

@@ -0,0 +1,53 @@
+import type { AgentTool } from "@earendil-works/pi-agent-core";
+import { fauxAssistantMessage, fauxToolCall } from "@earendil-works/pi-ai";
+import { Type } from "typebox";
+import { afterEach, describe, expect, it } from "vitest";
+import { createHarness, getAssistantTexts, type Harness } from "../harness.ts";
+
+describe("#5998 blocked tool termination", () => {
+	const harnesses: Harness[] = [];
+
+	afterEach(() => {
+		while (harnesses.length > 0) {
+			harnesses.pop()?.cleanup();
+		}
+	});
+
+	it("lets a tool_call handler terminate the run after blocking execution", async () => {
+		const echoTool: AgentTool = {
+			name: "echo",
+			label: "Echo",
+			description: "Echo text back",
+			parameters: Type.Object({ text: Type.String() }),
+			execute: async () => {
+				throw new Error("tool should have been blocked");
+			},
+		};
+		const harness = await createHarness({
+			tools: [echoTool],
+			extensionFactories: [
+				(pi) => {
+					pi.on("tool_call", async () => ({
+						block: true,
+						reason: "Blocked by terminating policy",
+						terminate: true,
+					}));
+				},
+			],
+		});
+		harnesses.push(harness);
+		harness.setResponses([
+			fauxAssistantMessage([fauxToolCall("echo", { text: "hello" })], { stopReason: "toolUse" }),
+			fauxAssistantMessage("should not run"),
+		]);
+
+		await harness.session.prompt("hi");
+
+		expect(harness.getPendingResponseCount()).toBe(1);
+		expect(getAssistantTexts(harness)).not.toContain("should not run");
+		expect(harness.eventsOfType("tool_execution_end")[0]?.result).toHaveProperty("terminate", true);
+		expect(
+			harness.session.messages.find((message) => message.role === "toolResult" && message.isError),
+		).toBeDefined();
+	});
+});