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/codemode/examples/cloudflare/agent/src/index.ts

@@ -0,0 +1,50 @@
+// A Worker whose Durable Object runs codemode the way an agent session would: tools run here, in the
+// session object, and scripts run in the separately deployed pi-codemode-sandbox Worker.
+//
+//   curl -X POST http://localhost:8787 --data 'const n = await tools.count({ add: 2 }); text("n=" + n); return n'
+import type { CodemodeSandboxDurableObject } from "@earendil-works/pi-codemode/cloudflare";
+// The portable entry has no QuickJS module: the WebAssembly lives only in the sandbox Worker.
+import { type CodemodeTool, RemoteCodemodeSandbox } from "@earendil-works/pi-codemode/portable";
+import { DurableObject } from "cloudflare:workers";
+
+interface Env {
+	SESSION: DurableObjectNamespace<Session>;
+	CODEMODE_SANDBOX: DurableObjectNamespace<CodemodeSandboxDurableObject>;
+}
+
+export class Session extends DurableObject<Env> {
+	private counter = 0;
+
+	async runCodemode(code: string) {
+		const tools: CodemodeTool[] = [
+			{
+				name: "count",
+				description: "Adds to a counter kept in the session and returns the new value",
+				execute: (args) => {
+					this.counter += (args as { add: number }).add;
+					return this.counter;
+				},
+			},
+		];
+		// Before: new CodemodeSandbox({ tools, timeoutMs: 60_000 })
+		const sandbox = new RemoteCodemodeSandbox({
+			tools,
+			timeoutMs: 60_000,
+			// One sandbox instance per session keeps a session's scripts together and apart from others.
+			remote: () => this.env.CODEMODE_SANDBOX.getByName(this.ctx.id.toString()),
+		});
+		try {
+			return await sandbox.execute(code);
+		} finally {
+			await sandbox.close();
+		}
+	}
+}
+
+export default {
+	async fetch(request, env) {
+		if (request.method !== "POST") return new Response("POST a script\n", { status: 405 });
+		const result = await env.SESSION.getByName("demo").runCodemode(await request.text());
+		return Response.json(result);
+	},
+} satisfies ExportedHandler<Env>;