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/fixtures/keyed-service.ts

@@ -0,0 +1,9 @@
+import { type Context, defineService, type ReplicatedState } from "@earendil-works/chord";
+
+export interface KeyedProbe {
+	readonly state: ReplicatedState<{ value: string }>;
+	replace(value: string, context: Context): Promise<void>;
+	wait(context: Context): Promise<void>;
+}
+
+export const KeyedProbe = defineService<KeyedProbe>("test.keyed-probe");