refactor: make workspace descriptors schema v3 only

backend/src/workspaces/bindings.ts

@@ -9,6 +9,7 @@ import {
   type VectorTransport,
   type WorkspaceDescriptor,
 } from "./schema.js";
+import type { DeprecatedV2Descriptor } from "./deprecated-v2-descriptor.js";
 
 export interface ResolvedEvidenceBinding {
   values: Record<string, string>;
@@ -85,7 +86,7 @@ function requiredSuffixes(
   const required = REQUIRED_SUFFIXES[role][transport] ?? [];
   const diagnostic = role === "DWH"
     ? workspace.diagnostics?.dwh_rest
-    : workspace.diagnostics?.vector_rest?.metadata;
+    : (workspace as unknown as DeprecatedV2Descriptor).diagnostics?.vector_rest?.metadata;
   return transport === "rest_api" && diagnostic?.auth === "none"
     ? required.filter((suffix) => suffix !== "API_KEY_FILE")
     : required;
@@ -107,14 +108,13 @@ export function resolveBinding(
   }
 
   const contract = buildInstallationContract(descriptor);
+  const legacy = descriptor as unknown as DeprecatedV2Descriptor;
   const variables = contract.variables.filter((variable) => variable.role === role);
   const transportVariable = variables.find((variable) => variable.suffix === "TRANSPORT");
   const supported = role === "DWH"
     ? descriptor.dwh.supported_transports
     : role === "VECTOR"
-      ? ("supported_transports" in descriptor.semantic_index.vector_store
-        ? descriptor.semantic_index.vector_store.supported_transports
-        : [])
+      ? legacy.semantic_index.vector_store.supported_transports
       : ["rest_api"] as const;
   const selectedValue = transportVariable ? env[transportVariable.name] : undefined;
   const selectedTransport = isTransport(selectedValue) ? selectedValue : supported[0];