chore: clean diagnostics and prepare for designer structural refactor (stub legacy useActiveStudy)

src/hooks/useSelectedStudyDetails.ts

@@ -0,0 +1,123 @@
+import { useCallback, useMemo } from "react";
+import { api } from "~/trpc/react";
+import { useStudyContext } from "~/lib/study-context";
+
+/**
+ * useSelectedStudyDetails
+ *
+ * Strongly typed unified source of truth for the currently selected study.
+ *
+ * Provides a single hook to retrieve:
+ * - selected study id
+ * - lightweight summary counts
+ * - role + createdAt
+ * - loading / fetching flags
+ * - mutation helpers
+ */
+
+interface StudyRelatedEntity {
+  id: string;
+}
+
+interface StudyMember {
+  id: string;
+  userId?: string;
+  role?: string;
+}
+
+interface StudyDetails {
+  id: string;
+  name: string;
+  description: string | null;
+  status: string;
+  experiments?: StudyRelatedEntity[];
+  participants?: StudyRelatedEntity[];
+  members?: StudyMember[];
+  userRole?: string;
+  createdAt?: Date;
+}
+
+export interface StudySummary {
+  id: string;
+  name: string;
+  description: string;
+  status: string;
+  experimentCount: number;
+  participantCount: number;
+  memberCount: number;
+  userRole?: string;
+  createdAt?: Date;
+}
+
+export interface UseSelectedStudyDetailsReturn {
+  studyId: string | null;
+  study: StudySummary | null;
+  isLoading: boolean;
+  isFetching: boolean;
+  refetch: () => Promise<unknown>;
+  setStudyId: (id: string | null) => void;
+  clearStudy: () => void;
+  hasStudy: boolean;
+}
+
+export function useSelectedStudyDetails(): UseSelectedStudyDetailsReturn {
+  const { selectedStudyId, setSelectedStudyId } = useStudyContext();
+
+  const { data, isLoading, isFetching, refetch } = api.studies.get.useQuery(
+    { id: selectedStudyId ?? "" },
+    {
+      enabled: !!selectedStudyId,
+      refetchOnWindowFocus: false,
+      staleTime: 5 * 60 * 1000,
+    },
+  );
+
+  const study: StudySummary | null = useMemo(() => {
+    if (!data || !selectedStudyId) return null;
+
+    // data is inferred from tRPC; we defensively narrow array fields
+    const typed = data as StudyDetails;
+
+    const experiments = Array.isArray(typed.experiments)
+      ? typed.experiments
+      : [];
+    const participants = Array.isArray(typed.participants)
+      ? typed.participants
+      : [];
+    const members = Array.isArray(typed.members) ? typed.members : [];
+
+    return {
+      id: typed.id,
+      name: typed.name ?? "Unnamed Study",
+      description: typed.description ?? "",
+      status: typed.status ?? "active",
+      experimentCount: experiments.length,
+      participantCount: participants.length,
+      memberCount: members.length,
+      userRole: typed.userRole,
+      createdAt: typed.createdAt,
+    };
+  }, [data, selectedStudyId]);
+
+  const setStudyId = useCallback(
+    (id: string | null) => {
+      void setSelectedStudyId(id);
+    },
+    [setSelectedStudyId],
+  );
+
+  const clearStudy = useCallback(() => {
+    void setSelectedStudyId(null);
+  }, [setSelectedStudyId]);
+
+  return {
+    studyId: selectedStudyId,
+    study,
+    isLoading,
+    isFetching,
+    refetch,
+    setStudyId,
+    clearStudy,
+    hasStudy: !!study,
+  };
+}