feat(core): add embedded v2 session runtime and tool foundation (#30632)

packages/core/src/schema.ts

@@ -1,4 +1,12 @@
 import { Option, Schema, SchemaGetter } from "effect"
+import { Hash } from "./util/hash"
+
+export type ExternalID = {
+  readonly namespace: string
+  readonly key: string
+}
+
+export const externalID = (prefix: string, input: ExternalID) => `${prefix}_${Hash.sha256(JSON.stringify([input.namespace, input.key]))}`
 
 /**
  * Integer greater than zero.