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/src/cli/experimental/cli.ts

@@ -0,0 +1,16 @@
+import { Command } from "./command.ts";
+import { type ClientCommandContext, clientCommand } from "./commands/client.ts";
+import { type ServerCommandContext, serverCommand } from "./commands/server.ts";
+
+interface ExperimentalCommandGroup {
+	readonly command: "experimental";
+}
+
+export type CliContext = ServerCommandContext & ClientCommandContext;
+
+const experimentalCommand = new Command<ExperimentalCommandGroup, CliContext>("experimental").build(() => ({
+	ok: false,
+	errors: ["Expected experimental command: server or client"],
+}));
+
+export const cli = experimentalCommand.command(serverCommand).command(clientCommand);