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

src/capability-model/execution.ts

@@ -67,15 +67,10 @@ export function validateExecutionContracts(workspace: WorkspaceRevision): Capabi
           );
           const selected = requirement.operations;
           if (requirement.receiver === "input") {
-            if (
-              entry.execution?.kind !== "snapshot" ||
-              entry.execution.targets.length !== 1 ||
-              entry.execution.targets[0] !== "server" ||
-              !selected?.length
-            )
+            if (!entry.execution || entry.execution.kind === "remote" || !selected?.length)
               fail(
                 portPath,
-                "Reference-selected reads currently require a server-only snapshot and an explicit selection; local acquisition of dynamic inputs is not implemented",
+                "Reference-selected reads require a portable snapshot or transaction and an explicit selection",
               );
             for (const id of selected ?? []) {
               const operation = contract && operations(id, contract);
@@ -108,6 +103,9 @@ export function validateExecutionContracts(workspace: WorkspaceRevision): Capabi
             fail(portPath, "Portable operations require a local query dependency");
         } else if (requirement.kind === "creation") {
           if (entry.execution.kind !== "transaction") fail(portPath, "Object creation requires transaction execution");
+        } else if (requirement.kind === "reflection") {
+          if (requirement.selectors.some((selector) => selector !== "presentations"))
+            fail(portPath, "Only checked presentation metadata is portable");
         } else if (requirement.kind !== "interface")
           fail(portPath, `Portable execution does not support ${requirement.kind} dependencies`);
       }

src/capability-model/validation.ts

@@ -1065,7 +1065,10 @@ const validatePackages = (
               !port.requirement.selectors.length ||
               new Set(port.requirement.selectors).size !== port.requirement.selectors.length ||
               port.requirement.selectors.some(
-                (kind) => !["active", "atoms", "interfaces", "conformances", "queries", "indexes"].includes(kind),
+                (kind) =>
+                  !["active", "atoms", "interfaces", "conformances", "queries", "indexes", "presentations"].includes(
+                    kind,
+                  ),
               )
             )
               issue(issues, "invalid-dependency-binding", portPath, "Reflection requires distinct supported selectors");