test(827): capture Gate0 runtime evidence

docs/compaction-refresh/probes/pi_later_extension.ts

@@ -0,0 +1,8 @@
+import type { ExtensionAPI } from '@earendil-works/pi-coding-agent';
+
+// Deliberately loaded after pi_gate0_extension.ts. The Gate0 extension must
+// observe its argv position and remain CLOSED rather than claiming finality.
+export default function register(pi: ExtensionAPI) {
+  pi.on('context', async (event) => ({ messages: [...event.messages] }));
+  pi.on('before_provider_request', async () => undefined);
+}