Implement Studio root and placement capabilities on the replica graph (WI-10)

src/execution-world/ports.ts

@@ -2,6 +2,7 @@
  * operation/port schema by the coordinator, not trusted because this header parsed. */
 export const transactionPortAbi = "quixos-transaction-ports-v1";
 export type PortAction =
+  | { kind: "reflection"; selector: string }
   | { kind: "state"; primitive: "read" | "write" | "edit" }
   | { kind: "edge"; primitive: "resolve" | "disconnect" }
   | { kind: "edge"; primitive: "connect"; key: string }
@@ -75,7 +76,9 @@ export function checkPortInvocation(value: unknown): PortInvocation {
             identifier(action.operationId)
           : action.kind === "creation"
             ? exact(["kind", "key"]) && identifier(action.key)
-            : action.kind === "query" && exact(["kind"]);
+            : action.kind === "reflection"
+              ? exact(["kind", "selector"]) && identifier(action.selector)
+              : action.kind === "query" && exact(["kind"]);
   if (!valid) throw new Error("Invalid port action");
   return { ...fields, action: { ...action } } as unknown as PortInvocation;
 }