diff --git a/apps/web/src/app/(authenticated)/knowledge/[slug]/page.tsx b/apps/web/src/app/(authenticated)/knowledge/[slug]/page.tsx
index 9f508b5..c01e85d 100644
--- a/apps/web/src/app/(authenticated)/knowledge/[slug]/page.tsx
+++ b/apps/web/src/app/(authenticated)/knowledge/[slug]/page.tsx
@@ -256,7 +256,13 @@ export default function EntryPage(): ReactElement {
   }
 
   if (!entry) {
-    return null;
+    return (
+      <div className="max-w-4xl mx-auto p-6">
+        <div className="p-4 bg-gray-50 dark:bg-gray-900/20 border border-gray-200 dark:border-gray-800 rounded-md">
+          <p className="text-sm text-gray-800 dark:text-gray-200">Entry not found</p>
+        </div>
+      </div>
+    );
   }
 
   return (
diff --git a/apps/web/src/app/(authenticated)/knowledge/new/page.tsx b/apps/web/src/app/(authenticated)/knowledge/new/page.tsx
index e5c38e3..fa44e1c 100644
--- a/apps/web/src/app/(authenticated)/knowledge/new/page.tsx
+++ b/apps/web/src/app/(authenticated)/knowledge/new/page.tsx
@@ -1,6 +1,6 @@
 "use client";
 
-import type { ReactElement, FormEvent as ReactFormEvent } from "react";
+import type { ReactElement } from "react";
 import React, { useState, useEffect, useCallback } from "react";
 import { useRouter } from "next/navigation";
 import { EntryStatus, Visibility, type KnowledgeTag } from "@mosaic/shared";
@@ -107,7 +107,7 @@ export default function NewEntryPage(): ReactElement {
     }
   };
 
-  const handleSubmit = (e: ReactFormEvent): void => {
+  const handleSubmit = (e: React.SyntheticEvent<HTMLFormElement>): void => {
     e.preventDefault();
     void handleSave();
   };
diff --git a/apps/web/src/app/(authenticated)/layout.tsx b/apps/web/src/app/(authenticated)/layout.tsx
index ae8e89e..da355db 100644
--- a/apps/web/src/app/(authenticated)/layout.tsx
+++ b/apps/web/src/app/(authenticated)/layout.tsx
@@ -6,7 +6,11 @@ import { useAuth } from "@/lib/auth/auth-context";
 import { Navigation } from "@/components/layout/Navigation";
 import type { ReactNode } from "react";
 
-export default function AuthenticatedLayout({ children }: { children: ReactNode }): React.JSX.Element | null {
+export default function AuthenticatedLayout({
+  children,
+}: {
+  children: ReactNode;
+}): React.JSX.Element | null {
   const router = useRouter();
   const { isAuthenticated, isLoading } = useAuth();
 
diff --git a/apps/web/src/app/(authenticated)/settings/workspaces/[id]/page.tsx b/apps/web/src/app/(authenticated)/settings/workspaces/[id]/page.tsx
index f0db3a1..9ff46dd 100644
--- a/apps/web/src/app/(authenticated)/settings/workspaces/[id]/page.tsx
+++ b/apps/web/src/app/(authenticated)/settings/workspaces/[id]/page.tsx
@@ -79,14 +79,16 @@ const mockMembers: WorkspaceMemberWithUser[] = [
   },
 ];
 
-export default function WorkspaceDetailPage({ params }: WorkspaceDetailPageProps): React.JSX.Element {
+export default function WorkspaceDetailPage({
+  params,
+}: WorkspaceDetailPageProps): React.JSX.Element {
   const router = useRouter();
   const [workspace, setWorkspace] = useState<Workspace>(mockWorkspace);
   const [members, setMembers] = useState<WorkspaceMemberWithUser[]>(mockMembers);
   const currentUserId = "user-1"; // TODO: Get from auth context
   const currentUserRole = WorkspaceMemberRole.OWNER; // TODO: Get from API
 
-  const canInvite = currentUserRole === WorkspaceMemberRole.ADMIN;
+  const canInvite = currentUserRole === WorkspaceMemberRole.OWNER || currentUserRole === WorkspaceMemberRole.ADMIN;
 
   const handleUpdateWorkspace = async (name: string): Promise<void> => {
     // TODO: Replace with real API call
diff --git a/apps/web/src/app/(authenticated)/settings/workspaces/page.tsx b/apps/web/src/app/(authenticated)/settings/workspaces/page.tsx
index 82137a9..9f08839 100644
--- a/apps/web/src/app/(authenticated)/settings/workspaces/page.tsx
+++ b/apps/web/src/app/(authenticated)/settings/workspaces/page.tsx
@@ -46,7 +46,7 @@ export default function WorkspacesPage(): ReactElement {
     };
   });
 
-  const handleCreateWorkspace = async (e: React.FormEvent) => {
+  const handleCreateWorkspace = async (e: React.SyntheticEvent<HTMLFormElement>) => {
     e.preventDefault();
     if (!newWorkspaceName.trim()) return;
 
diff --git a/apps/web/src/app/(authenticated)/tasks/page.test.tsx b/apps/web/src/app/(authenticated)/tasks/page.test.tsx
index 02bb527..20bd330 100644
--- a/apps/web/src/app/(authenticated)/tasks/page.test.tsx
+++ b/apps/web/src/app/(authenticated)/tasks/page.test.tsx
@@ -5,7 +5,7 @@ import TasksPage from "./page";
 // Mock the TaskList component
 vi.mock("@/components/tasks/TaskList", () => ({
   TaskList: ({ tasks, isLoading }: { tasks: unknown[]; isLoading: boolean }) => (
-    <div data-testid="task-list">{isLoading ? "Loading" : `${tasks.length} tasks`}</div>
+    <div data-testid="task-list">{isLoading ? "Loading" : `${String(tasks.length)} tasks`}</div>
   ),
 }));
 
diff --git a/apps/web/src/app/settings/workspaces/[id]/teams/[teamId]/page.tsx b/apps/web/src/app/settings/workspaces/[id]/teams/[teamId]/page.tsx
index 5e9fec6..3dd7cce 100644
--- a/apps/web/src/app/settings/workspaces/[id]/teams/[teamId]/page.tsx
+++ b/apps/web/src/app/settings/workspaces/[id]/teams/[teamId]/page.tsx
@@ -52,14 +52,14 @@ export default function TeamDetailPage(): ReactElement {
   const [team] = useState(mockTeamWithMembers);
   const [isLoading] = useState(false);
 
-  const handleUpdateTeam = (data: { name?: string; description?: string }): void => {
+  const handleUpdateTeam = async (data: { name?: string; description?: string }): Promise<void> => {
     // TODO: Replace with real API call
     // await updateTeam(workspaceId, teamId, data);
     console.log("Updating team:", data);
     // TODO: Refetch team data
   };
 
-  const handleDeleteTeam = (): void => {
+  const handleDeleteTeam = async (): Promise<void> => {
     // TODO: Replace with real API call
     // await deleteTeam(workspaceId, teamId);
     console.log("Deleting team");
@@ -68,14 +68,14 @@ export default function TeamDetailPage(): ReactElement {
     router.push(`/settings/workspaces/${workspaceId}/teams`);
   };
 
-  const handleAddMember = (userId: string, role?: TeamMemberRole): void => {
+  const handleAddMember = async (userId: string, role?: TeamMemberRole): Promise<void> => {
     // TODO: Replace with real API call
     // await addTeamMember(workspaceId, teamId, { userId, role });
     console.log("Adding member:", { userId, role });
     // TODO: Refetch team data
   };
 
-  const handleRemoveMember = (userId: string): void => {
+  const handleRemoveMember = async (userId: string): Promise<void> => {
     // TODO: Replace with real API call
     // await removeTeamMember(workspaceId, teamId, userId);
     console.log("Removing member:", userId);
diff --git a/apps/web/src/app/settings/workspaces/[id]/teams/page.tsx b/apps/web/src/app/settings/workspaces/[id]/teams/page.tsx
index be5f2cb..c64a8ee 100644
--- a/apps/web/src/app/settings/workspaces/[id]/teams/page.tsx
+++ b/apps/web/src/app/settings/workspaces/[id]/teams/page.tsx
@@ -107,7 +107,11 @@ export default function TeamsPage(): ReactElement {
       {showCreateModal && (
         <Modal
           isOpen={showCreateModal}
-          onClose={() => !isCreating && setShowCreateModal(false)}
+          onClose={() => {
+            if (!isCreating) {
+              setShowCreateModal(false);
+            }
+          }}
           title="Create New Team"
         >
           <div className="space-y-4">
diff --git a/apps/web/src/components/auth/LogoutButton.tsx b/apps/web/src/components/auth/LogoutButton.tsx
index 84dbcca..67ee894 100644
--- a/apps/web/src/components/auth/LogoutButton.tsx
+++ b/apps/web/src/components/auth/LogoutButton.tsx
@@ -16,7 +16,7 @@ export function LogoutButton({ variant = "secondary", className }: LogoutButtonP
   const handleSignOut = async () => {
     try {
       await signOut();
-    } catch (_error) {
+    } catch (error) {
       console.error("Sign out error:", error);
     } finally {
       router.push("/login");
diff --git a/apps/web/src/components/chat/BackendStatusBanner.tsx b/apps/web/src/components/chat/BackendStatusBanner.tsx
index c3a5f34..ed06099 100644
--- a/apps/web/src/components/chat/BackendStatusBanner.tsx
+++ b/apps/web/src/components/chat/BackendStatusBanner.tsx
@@ -25,7 +25,7 @@ export function BackendStatusBanner() {
     try {
       // NOTE: Implement signOut (see issue #TBD)
       // await signOut();
-    } catch (_error) {
+    } catch (error) {
       // Silently fail - will redirect anyway
       void error;
     }
@@ -63,8 +63,8 @@ export function BackendStatusBanner() {
           />
         </svg>
         <span>
-          {error || "Backend temporarily unavailable."}
-          {retryIn > 0 && <span className="ml-1">Retrying in {retryIn}s...</span>}
+          {_error || "Backend temporarily unavailable."}
+          {_retryIn > 0 && <span className="ml-1">Retrying in {_retryIn}s...</span>}
         </span>
       </div>
       <div className="flex items-center gap-2">
diff --git a/apps/web/src/components/chat/MessageList.tsx b/apps/web/src/components/chat/MessageList.tsx
index 61f4565..023cf03 100644
--- a/apps/web/src/components/chat/MessageList.tsx
+++ b/apps/web/src/components/chat/MessageList.tsx
@@ -122,7 +122,7 @@ function MessageBubble({ message }: { message: Message }) {
                 backgroundColor: "rgb(var(--surface-2))",
                 color: "rgb(var(--text-muted))",
               }}
-              title={`Prompt: ${message.promptTokens?.toLocaleString() || 0} tokens, Completion: ${message.completionTokens?.toLocaleString() || 0} tokens`}
+              title={`Prompt: ${message.promptTokens?.toLocaleString() || "0"} tokens, Completion: ${message.completionTokens?.toLocaleString() || "0"} tokens`}
             >
               {formatTokenCount(message.totalTokens)} tokens
             </span>
diff --git a/apps/web/src/components/dashboard/QuickCaptureWidget.tsx b/apps/web/src/components/dashboard/QuickCaptureWidget.tsx
index 441b3b0..77079c2 100644
--- a/apps/web/src/components/dashboard/QuickCaptureWidget.tsx
+++ b/apps/web/src/components/dashboard/QuickCaptureWidget.tsx
@@ -8,7 +8,7 @@ export function QuickCaptureWidget() {
   const [idea, setIdea] = useState("");
   const router = useRouter();
 
-  const handleSubmit = (e: React.FormEvent) => {
+  const handleSubmit = (e: React.SyntheticEvent<HTMLFormElement>) => {
     e.preventDefault();
     if (!idea.trim()) return;
 
diff --git a/apps/web/src/components/domains/DomainSelector.test.tsx b/apps/web/src/components/domains/DomainSelector.test.tsx
index fa577ec..a048e57 100644
--- a/apps/web/src/components/domains/DomainSelector.test.tsx
+++ b/apps/web/src/components/domains/DomainSelector.test.tsx
@@ -88,7 +88,7 @@ describe("DomainSelector", (): void => {
     const onChange = vi.fn();
     render(<DomainSelector domains={mockDomains} value="domain-1" onChange={onChange} />);
 
-    const select = screen.getByRole("combobox");
+    const select = screen.getByRole("combobox") as HTMLSelectElement;
     expect(select.value).toBe("domain-1");
   });
 
diff --git a/apps/web/src/components/filters/FilterBar.tsx b/apps/web/src/components/filters/FilterBar.tsx
index d1158c6..46d2d9c 100644
--- a/apps/web/src/components/filters/FilterBar.tsx
+++ b/apps/web/src/components/filters/FilterBar.tsx
@@ -50,7 +50,7 @@ export function FilterBar({
   }, [searchValue, debounceMs]);
 
   const handleFilterChange = useCallback(
-    (key: keyof FilterValues, value: any) => {
+    (key: keyof FilterValues, value: FilterValues[keyof FilterValues]) => {
       const newFilters = { ...filters, [key]: value };
       if (!value || (Array.isArray(value) && value.length === 0)) {
         delete newFilters[key];
diff --git a/apps/web/src/components/hud/WidgetGrid.tsx b/apps/web/src/components/hud/WidgetGrid.tsx
index 5571f90..0d81084 100644
--- a/apps/web/src/components/hud/WidgetGrid.tsx
+++ b/apps/web/src/components/hud/WidgetGrid.tsx
@@ -87,9 +87,9 @@ export function WidgetGrid({
     return layoutItem;
   });
 
-  const handleLayoutChange = (layout: readonly any[]) => {
+  const handleLayoutChange = (layout: readonly WidgetPlacement[]) => {
     if (onLayoutChange) {
-      onLayoutChange([...layout] as WidgetPlacement[]);
+      onLayoutChange(layout);
     }
   };
 
diff --git a/apps/web/src/components/kanban/KanbanBoard.test.tsx b/apps/web/src/components/kanban/KanbanBoard.test.tsx
index 51da262..ae2f5f9 100644
--- a/apps/web/src/components/kanban/KanbanBoard.test.tsx
+++ b/apps/web/src/components/kanban/KanbanBoard.test.tsx
@@ -226,8 +226,8 @@ describe("KanbanBoard", (): void => {
       const fetchMock = global.fetch as ReturnType<typeof vi.fn>;
       fetchMock.mockResolvedValueOnce({
         ok: true,
-        json: () => ({ status: TaskStatus.IN_PROGRESS }),
-      } as Response);
+        json: () => Promise.resolve({ status: TaskStatus.IN_PROGRESS }),
+      } as unknown as Response);
 
       render(<KanbanBoard tasks={mockTasks} onStatusChange={mockOnStatusChange} />);
 
diff --git a/apps/web/src/components/kanban/KanbanBoard.tsx b/apps/web/src/components/kanban/KanbanBoard.tsx
index 18d93c5..ce5e516 100644
--- a/apps/web/src/components/kanban/KanbanBoard.tsx
+++ b/apps/web/src/components/kanban/KanbanBoard.tsx
@@ -110,7 +110,7 @@ export function KanbanBoard({ tasks, onStatusChange }: KanbanBoardProps): React.
         if (onStatusChange) {
           onStatusChange(taskId, newStatus);
         }
-      } catch (_error) {
+      } catch (error) {
         console.error("Error updating task status:", error);
         // TODO: Show error toast/notification
       }
diff --git a/apps/web/src/components/knowledge/ImportExportActions.tsx b/apps/web/src/components/knowledge/ImportExportActions.tsx
index 4792f76..77c167f 100644
--- a/apps/web/src/components/knowledge/ImportExportActions.tsx
+++ b/apps/web/src/components/knowledge/ImportExportActions.tsx
@@ -80,7 +80,7 @@ export function ImportExportActions({
       if (result.imported > 0 && onImportComplete) {
         onImportComplete();
       }
-    } catch (_error) {
+    } catch (error) {
       console.error("Import error:", error);
       alert(error instanceof Error ? error.message : "Failed to import file");
       setShowImportDialog(false);
@@ -135,7 +135,7 @@ export function ImportExportActions({
       a.click();
       window.URL.revokeObjectURL(url);
       document.body.removeChild(a);
-    } catch (_error) {
+    } catch (error) {
       console.error("Export error:", error);
       alert("Failed to export entries");
     } finally {
diff --git a/apps/web/src/components/knowledge/LinkAutocomplete.tsx b/apps/web/src/components/knowledge/LinkAutocomplete.tsx
index 2c81ae6..e4a94cb 100644
--- a/apps/web/src/components/knowledge/LinkAutocomplete.tsx
+++ b/apps/web/src/components/knowledge/LinkAutocomplete.tsx
@@ -8,7 +8,7 @@ interface LinkAutocompleteProps {
   /**
    * The textarea element to attach autocomplete to
    */
-  textareaRef: React.RefObject<HTMLTextAreaElement>;
+  textareaRef: React.RefObject<HTMLTextAreaElement | null>;
   /**
    * Callback when a link is selected
    */
@@ -82,7 +82,7 @@ export function LinkAutocomplete({
 
       setResults(searchResults);
       setSelectedIndex(0);
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to search entries:", error);
       setResults([]);
     } finally {
@@ -116,7 +116,7 @@ export function LinkAutocomplete({
       const styles = window.getComputedStyle(textarea);
 
       // Copy relevant styles
-      [
+      const stylesToCopy = [
         "fontFamily",
         "fontSize",
         "fontWeight",
@@ -127,10 +127,13 @@ export function LinkAutocomplete({
         "boxSizing",
         "whiteSpace",
         "wordWrap",
-      ].forEach((prop) => {
-        mirror.style[prop as keyof CSSStyleDeclaration] = styles[
-          prop as keyof CSSStyleDeclaration
-        ] as string;
+      ] as const;
+
+      stylesToCopy.forEach((prop) => {
+        const value = styles.getPropertyValue(prop);
+        if (value) {
+          mirror.style.setProperty(prop, value);
+        }
       });
 
       mirror.style.position = "absolute";
diff --git a/apps/web/src/components/knowledge/__tests__/EntryEditor.test.tsx b/apps/web/src/components/knowledge/__tests__/EntryEditor.test.tsx
index 8b20970..3e9d537 100644
--- a/apps/web/src/components/knowledge/__tests__/EntryEditor.test.tsx
+++ b/apps/web/src/components/knowledge/__tests__/EntryEditor.test.tsx
@@ -31,7 +31,7 @@ describe("EntryEditor", (): void => {
     const content = "# Test Content\n\nThis is a test.";
     render(<EntryEditor {...defaultProps} content={content} />);
 
-    const textarea = screen.getByPlaceholderText(/Write your content here/);
+    const textarea = screen.getByPlaceholderText(/Write your content here/) as HTMLTextAreaElement;
     expect(textarea.value).toBe(content);
   });
 
@@ -112,7 +112,7 @@ describe("EntryEditor", (): void => {
     render(<EntryEditor {...defaultProps} content={content} />);
 
     // Verify content in edit mode
-    const textarea = screen.getByPlaceholderText(/Write your content here/);
+    const textarea = screen.getByPlaceholderText(/Write your content here/) as HTMLTextAreaElement;
     expect(textarea.value).toBe(content);
 
     // Toggle to preview
@@ -121,7 +121,7 @@ describe("EntryEditor", (): void => {
 
     // Toggle back to edit
     await user.click(screen.getByText("Edit"));
-    const textareaAfter = screen.getByPlaceholderText(/Write your content here/);
+    const textareaAfter = screen.getByPlaceholderText(/Write your content here/) as HTMLTextAreaElement;
     expect(textareaAfter.value).toBe(content);
   });
 
diff --git a/apps/web/src/components/knowledge/__tests__/LinkAutocomplete.test.tsx b/apps/web/src/components/knowledge/__tests__/LinkAutocomplete.test.tsx
index f32d1a3..605218f 100644
--- a/apps/web/src/components/knowledge/__tests__/LinkAutocomplete.test.tsx
+++ b/apps/web/src/components/knowledge/__tests__/LinkAutocomplete.test.tsx
@@ -380,7 +380,12 @@ describe("LinkAutocomplete", (): void => {
     const searchPromise = new Promise((resolve) => {
       resolveSearch = resolve;
     });
-    mockApiGet.mockReturnValue(searchPromise as Promise<any>);
+    mockApiGet.mockReturnValue(
+      searchPromise as Promise<{
+        data: unknown[];
+        meta: { total: number; page: number; limit: number; totalPages: number };
+      }>
+    );
 
     render(<LinkAutocomplete textareaRef={textareaRef} onInsert={onInsertMock} />);
 
diff --git a/apps/web/src/components/knowledge/index.ts b/apps/web/src/components/knowledge/index.ts
index a6a0929..f97bfec 100644
--- a/apps/web/src/components/knowledge/index.ts
+++ b/apps/web/src/components/knowledge/index.ts
@@ -7,3 +7,4 @@ export { EntryEditor } from "./EntryEditor";
 export { EntryMetadata } from "./EntryMetadata";
 export { VersionHistory } from "./VersionHistory";
 export { ImportExportActions } from "./ImportExportActions";
+export { StatsDashboard } from "./StatsDashboard";
diff --git a/apps/web/src/components/mindmap/controls/ExportButton.tsx b/apps/web/src/components/mindmap/controls/ExportButton.tsx
index b0d470e..9d9a3c4 100644
--- a/apps/web/src/components/mindmap/controls/ExportButton.tsx
+++ b/apps/web/src/components/mindmap/controls/ExportButton.tsx
@@ -123,9 +123,10 @@ export function ExportButton({ graph, mermaid }: ExportButtonProps) {
       case "mermaid":
         exportAsMermaid();
         break;
-      case "png":
+      case "png": {
         await exportAsPng();
         break;
+      }
       case "svg":
         exportAsSvg();
         break;
diff --git a/apps/web/src/components/mindmap/controls/NodeCreateModal.tsx b/apps/web/src/components/mindmap/controls/NodeCreateModal.tsx
index 6eff98e..a460f50 100644
--- a/apps/web/src/components/mindmap/controls/NodeCreateModal.tsx
+++ b/apps/web/src/components/mindmap/controls/NodeCreateModal.tsx
@@ -26,13 +26,13 @@ export function NodeCreateModal({ onClose, onCreate }: NodeCreateModalProps) {
   const [domain, setDomain] = useState("");
   const [isSubmitting, setIsSubmitting] = useState(false);
 
-  const handleSubmit = async (e: React.FormEvent) => {
+  const handleSubmit = async (e: React.SyntheticEvent<HTMLFormElement>) => {
     e.preventDefault();
     if (!title.trim()) return;
 
     setIsSubmitting(true);
     try {
-      await onCreate({
+      const result = await onCreate({
         title: title.trim(),
         node_type: nodeType,
         content: content.trim() || null,
@@ -43,6 +43,7 @@ export function NodeCreateModal({ onClose, onCreate }: NodeCreateModalProps) {
         domain: domain.trim() || null,
         metadata: {},
       });
+      return result;
     } finally {
       setIsSubmitting(false);
     }
diff --git a/apps/web/src/components/mindmap/hooks/useGraphData.ts b/apps/web/src/components/mindmap/hooks/useGraphData.ts
index 6b1ed76..892fc44 100644
--- a/apps/web/src/components/mindmap/hooks/useGraphData.ts
+++ b/apps/web/src/components/mindmap/hooks/useGraphData.ts
@@ -284,7 +284,7 @@ export function useGraphData(options: UseGraphDataOptions = {}): UseGraphDataRes
   }, [accessToken]);
 
   const fetchMermaid = useCallback(
-    (style: "flowchart" | "mindmap" = "flowchart"): void => {
+    async (style: "flowchart" | "mindmap" = "flowchart"): Promise<void> => {
       if (!graph) {
         setError("No graph data available");
         return;
@@ -356,7 +356,7 @@ export function useGraphData(options: UseGraphDataOptions = {}): UseGraphDataRes
     [graph]
   );
 
-  const fetchStatistics = useCallback((): void => {
+  const fetchStatistics = useCallback(async (): Promise<void> => {
     if (!graph) return;
 
     try {
@@ -577,7 +577,7 @@ export function useGraphData(options: UseGraphDataOptions = {}): UseGraphDataRes
   // Update statistics when graph changes
   useEffect(() => {
     if (graph) {
-      void fetchStatistics();
+      fetchStatistics();
     }
   }, [graph, fetchStatistics]);
 
diff --git a/apps/web/src/components/personalities/PersonalityForm.tsx b/apps/web/src/components/personalities/PersonalityForm.tsx
index cc92519..aad5ff2 100644
--- a/apps/web/src/components/personalities/PersonalityForm.tsx
+++ b/apps/web/src/components/personalities/PersonalityForm.tsx
@@ -56,7 +56,7 @@ export function PersonalityForm({
   });
   const [isSubmitting, setIsSubmitting] = useState(false);
 
-  async function handleSubmit(e: React.FormEvent): Promise<void> {
+  async function handleSubmit(e: React.SyntheticEvent<HTMLFormElement>): Promise<void> {
     e.preventDefault();
     setIsSubmitting(true);
     try {
diff --git a/apps/web/src/components/team/TeamMemberList.tsx b/apps/web/src/components/team/TeamMemberList.tsx
index f906d87..5446268 100644
--- a/apps/web/src/components/team/TeamMemberList.tsx
+++ b/apps/web/src/components/team/TeamMemberList.tsx
@@ -41,7 +41,7 @@ export function TeamMemberList({
       await onAddMember(selectedUserId, selectedRole);
       setSelectedUserId("");
       setSelectedRole(TeamMemberRole.MEMBER);
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to add member:", error);
       alert("Failed to add member. Please try again.");
     } finally {
@@ -53,7 +53,7 @@ export function TeamMemberList({
     setRemovingUserId(userId);
     try {
       await onRemoveMember(userId);
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to remove member:", error);
       alert("Failed to remove member. Please try again.");
     } finally {
diff --git a/apps/web/src/components/team/TeamSettings.tsx b/apps/web/src/components/team/TeamSettings.tsx
index e032ba6..53471de 100644
--- a/apps/web/src/components/team/TeamSettings.tsx
+++ b/apps/web/src/components/team/TeamSettings.tsx
@@ -34,7 +34,7 @@ export function TeamSettings({ team, onUpdate, onDelete }: TeamSettingsProps) {
       }
       await onUpdate(updates);
       setIsEditing(false);
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to update team:", error);
       alert("Failed to update team. Please try again.");
     } finally {
@@ -52,7 +52,7 @@ export function TeamSettings({ team, onUpdate, onDelete }: TeamSettingsProps) {
     setIsDeleting(true);
     try {
       await onDelete();
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to delete team:", error);
       alert("Failed to delete team. Please try again.");
       setIsDeleting(false);
diff --git a/apps/web/src/components/ui/select.tsx b/apps/web/src/components/ui/select.tsx
index 153a15c..810bbd8 100644
--- a/apps/web/src/components/ui/select.tsx
+++ b/apps/web/src/components/ui/select.tsx
@@ -32,7 +32,12 @@ const SelectContext = React.createContext<{
   onValueChange?: (value: string) => void;
   isOpen: boolean;
   setIsOpen: (open: boolean) => void;
-}>({ isOpen: false, setIsOpen: () => {} });
+}>({
+  isOpen: false,
+  setIsOpen: () => {
+    // Default no-op
+  },
+});
 
 export function Select({ value, onValueChange, defaultValue, disabled, children }: SelectProps) {
   const [isOpen, setIsOpen] = React.useState(false);
diff --git a/apps/web/src/components/widgets/QuickCaptureWidget.tsx b/apps/web/src/components/widgets/QuickCaptureWidget.tsx
index 2db62f8..c933cda 100644
--- a/apps/web/src/components/widgets/QuickCaptureWidget.tsx
+++ b/apps/web/src/components/widgets/QuickCaptureWidget.tsx
@@ -11,7 +11,7 @@ export function QuickCaptureWidget({ id: _id, config: _config }: WidgetProps) {
   const [isSubmitting, setIsSubmitting] = useState(false);
   const [recentCaptures, setRecentCaptures] = useState<string[]>([]);
 
-  const handleSubmit = (e: React.FormEvent): void => {
+  const handleSubmit = (e: React.SyntheticEvent<HTMLFormElement>): void => {
     e.preventDefault();
     if (!input.trim() || isSubmitting) return;
 
diff --git a/apps/web/src/components/widgets/__tests__/CalendarWidget.test.tsx b/apps/web/src/components/widgets/__tests__/CalendarWidget.test.tsx
index 5c8f71f..04ceb70 100644
--- a/apps/web/src/components/widgets/__tests__/CalendarWidget.test.tsx
+++ b/apps/web/src/components/widgets/__tests__/CalendarWidget.test.tsx
@@ -15,9 +15,12 @@ describe("CalendarWidget", (): void => {
   });
 
   it("should render loading state initially", (): void => {
-    vi.mocked(global.fetch).mockImplementation(() => new Promise(() => {
-      // Intentionally never resolves to keep loading state
-    }));
+    vi.mocked(global.fetch).mockImplementation(
+      () =>
+        new Promise(() => {
+          // Intentionally never resolves to keep loading state
+        })
+    );
 
     render(<CalendarWidget id="calendar-1" />);
 
@@ -42,8 +45,8 @@ describe("CalendarWidget", (): void => {
 
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => mockEvents,
-    });
+      json: () => Promise.resolve(mockEvents),
+    } as unknown as Response);
 
     render(<CalendarWidget id="calendar-1" />);
 
@@ -56,8 +59,8 @@ describe("CalendarWidget", (): void => {
   it("should handle empty event list", async (): Promise<void> => {
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => [],
-    });
+      json: () => Promise.resolve([]),
+    } as unknown as Response);
 
     render(<CalendarWidget id="calendar-1" />);
 
@@ -91,8 +94,8 @@ describe("CalendarWidget", (): void => {
 
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => mockEvents,
-    });
+      json: () => Promise.resolve(mockEvents),
+    } as unknown as Response);
 
     render(<CalendarWidget id="calendar-1" />);
 
@@ -105,8 +108,8 @@ describe("CalendarWidget", (): void => {
   it("should display current date", async (): Promise<void> => {
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => [],
-    });
+      json: () => Promise.resolve([]),
+    } as unknown as Response);
 
     render(<CalendarWidget id="calendar-1" />);
 
diff --git a/apps/web/src/components/widgets/__tests__/QuickCaptureWidget.test.tsx b/apps/web/src/components/widgets/__tests__/QuickCaptureWidget.test.tsx
index e0457e1..b686975 100644
--- a/apps/web/src/components/widgets/__tests__/QuickCaptureWidget.test.tsx
+++ b/apps/web/src/components/widgets/__tests__/QuickCaptureWidget.test.tsx
@@ -41,8 +41,8 @@ describe("QuickCaptureWidget", (): void => {
     const user = userEvent.setup();
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => ({ success: true }),
-    });
+      json: () => Promise.resolve({ success: true }),
+    } as unknown as Response);
 
     render(<QuickCaptureWidget id="quick-capture-1" />);
 
@@ -66,8 +66,8 @@ describe("QuickCaptureWidget", (): void => {
     const user = userEvent.setup();
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => ({ success: true }),
-    });
+      json: () => Promise.resolve({ success: true }),
+    } as unknown as Response);
 
     render(<QuickCaptureWidget id="quick-capture-1" />);
 
@@ -113,8 +113,8 @@ describe("QuickCaptureWidget", (): void => {
     const user = userEvent.setup();
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => ({ success: true }),
-    });
+      json: () => Promise.resolve({ success: true }),
+    } as unknown as Response);
 
     render(<QuickCaptureWidget id="quick-capture-1" />);
 
@@ -130,8 +130,8 @@ describe("QuickCaptureWidget", (): void => {
     const user = userEvent.setup();
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => ({ success: true }),
-    });
+      json: () => Promise.resolve({ success: true }),
+    } as unknown as Response);
 
     render(<QuickCaptureWidget id="quick-capture-1" />);
 
diff --git a/apps/web/src/components/widgets/__tests__/TasksWidget.test.tsx b/apps/web/src/components/widgets/__tests__/TasksWidget.test.tsx
index 64469bd..0bd04a5 100644
--- a/apps/web/src/components/widgets/__tests__/TasksWidget.test.tsx
+++ b/apps/web/src/components/widgets/__tests__/TasksWidget.test.tsx
@@ -32,8 +32,8 @@ describe("TasksWidget", (): void => {
 
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => mockTasks,
-    });
+      json: () => Promise.resolve(mockTasks),
+    } as unknown as Response);
 
     render(<TasksWidget id="tasks-1" />);
 
@@ -52,8 +52,8 @@ describe("TasksWidget", (): void => {
 
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => mockTasks,
-    });
+      json: () => Promise.resolve(mockTasks),
+    } as unknown as Response);
 
     render(<TasksWidget id="tasks-1" />);
 
@@ -66,8 +66,8 @@ describe("TasksWidget", (): void => {
   it("should handle empty task list", async (): Promise<void> => {
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => [],
-    });
+      json: () => Promise.resolve([]),
+    } as unknown as Response);
 
     render(<TasksWidget id="tasks-1" />);
 
@@ -93,8 +93,8 @@ describe("TasksWidget", (): void => {
 
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => mockTasks,
-    });
+      json: () => Promise.resolve(mockTasks),
+    } as unknown as Response);
 
     render(<TasksWidget id="tasks-1" />);
 
@@ -114,8 +114,8 @@ describe("TasksWidget", (): void => {
 
     vi.mocked(global.fetch).mockResolvedValueOnce({
       ok: true,
-      json: () => mockTasks,
-    });
+      json: () => Promise.resolve(mockTasks),
+    } as unknown as Response);
 
     render(<TasksWidget id="tasks-1" />);
 
diff --git a/apps/web/src/components/widgets/__tests__/WidgetGrid.test.tsx b/apps/web/src/components/widgets/__tests__/WidgetGrid.test.tsx
index 1794d0b..cfaa923 100644
--- a/apps/web/src/components/widgets/__tests__/WidgetGrid.test.tsx
+++ b/apps/web/src/components/widgets/__tests__/WidgetGrid.test.tsx
@@ -10,8 +10,12 @@ import type { WidgetPlacement } from "@mosaic/shared";
 
 // Mock react-grid-layout
 vi.mock("react-grid-layout", () => ({
-  default: ({ children }: any) => <div data-testid="grid-layout">{children}</div>,
-  Responsive: ({ children }: any) => <div data-testid="responsive-grid-layout">{children}</div>,
+  default: ({ children }: { children: React.ReactNode }) => (
+    <div data-testid="grid-layout">{children}</div>
+  ),
+  Responsive: ({ children }: { children: React.ReactNode }) => (
+    <div data-testid="responsive-grid-layout">{children}</div>
+  ),
 }));
 
 describe("WidgetGrid", (): void => {
diff --git a/apps/web/src/components/workspace/InviteMember.tsx b/apps/web/src/components/workspace/InviteMember.tsx
index c3b1b40..bc9c9d3 100644
--- a/apps/web/src/components/workspace/InviteMember.tsx
+++ b/apps/web/src/components/workspace/InviteMember.tsx
@@ -13,7 +13,7 @@ export function InviteMember({ onInvite }: InviteMemberProps) {
   const [isInviting, setIsInviting] = useState(false);
   const [error, setError] = useState<string | null>(null);
 
-  const handleSubmit = async (e: React.FormEvent) => {
+  const handleSubmit = async (e: React.SyntheticEvent<HTMLFormElement>) => {
     e.preventDefault();
     setError(null);
 
@@ -33,7 +33,7 @@ export function InviteMember({ onInvite }: InviteMemberProps) {
       setEmail("");
       setRole(WorkspaceMemberRole.MEMBER);
       alert("Invitation sent successfully!");
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to invite member:", error);
       setError(
         error instanceof Error ? error.message : "Failed to send invitation. Please try again."
diff --git a/apps/web/src/components/workspace/MemberList.tsx b/apps/web/src/components/workspace/MemberList.tsx
index cb1e815..8788399 100644
--- a/apps/web/src/components/workspace/MemberList.tsx
+++ b/apps/web/src/components/workspace/MemberList.tsx
@@ -37,7 +37,7 @@ export function MemberList({
   const handleRoleChange = async (userId: string, newRole: WorkspaceMemberRole) => {
     try {
       await onRoleChange(userId, newRole);
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to change role:", error);
       alert("Failed to change member role");
     }
@@ -50,7 +50,7 @@ export function MemberList({
 
     try {
       await onRemove(userId);
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to remove member:", error);
       alert("Failed to remove member");
     }
diff --git a/apps/web/src/components/workspace/WorkspaceSettings.tsx b/apps/web/src/components/workspace/WorkspaceSettings.tsx
index 7a040b7..0c3c426 100644
--- a/apps/web/src/components/workspace/WorkspaceSettings.tsx
+++ b/apps/web/src/components/workspace/WorkspaceSettings.tsx
@@ -37,7 +37,7 @@ export function WorkspaceSettings({
     try {
       await onUpdate(name);
       setIsEditing(false);
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to update workspace:", error);
       alert("Failed to update workspace");
     } finally {
@@ -49,7 +49,7 @@ export function WorkspaceSettings({
     setIsDeleting(true);
     try {
       await onDelete();
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to delete workspace:", error);
       alert("Failed to delete workspace");
       setIsDeleting(false);
diff --git a/apps/web/src/hooks/__tests__/useLayouts.test.tsx b/apps/web/src/hooks/__tests__/useLayouts.test.tsx
index 2cd955b..997d84a 100644
--- a/apps/web/src/hooks/__tests__/useLayouts.test.tsx
+++ b/apps/web/src/hooks/__tests__/useLayouts.test.tsx
@@ -37,7 +37,7 @@ describe("useLayouts", (): void => {
       { id: "2", name: "Custom", isDefault: false, layout: [] },
     ];
 
-    (global.fetch as any).mockResolvedValueOnce({
+    (global.fetch as ReturnType<typeof vi.fn>).mockResolvedValueOnce({
       ok: true,
       json: () => mockLayouts,
     });
@@ -52,7 +52,7 @@ describe("useLayouts", (): void => {
   });
 
   it("should handle fetch errors", async (): Promise<void> => {
-    (global.fetch as any).mockRejectedValueOnce(new Error("API Error"));
+    (global.fetch as ReturnType<typeof vi.fn>).mockRejectedValueOnce(new Error("API Error"));
 
     const { result } = renderHook(() => useLayouts(), {
       wrapper: createWrapper(),
@@ -64,7 +64,7 @@ describe("useLayouts", (): void => {
   });
 
   it("should show loading state", (): void => {
-    (global.fetch as any).mockImplementation(() => new Promise(() => {}));
+    (global.fetch as ReturnType<typeof vi.fn>).mockImplementation(() => new Promise(() => {}));
 
     const { result } = renderHook(() => useLayouts(), {
       wrapper: createWrapper(),
@@ -87,7 +87,7 @@ describe("useCreateLayout", (): void => {
       layout: [],
     };
 
-    (global.fetch as any).mockResolvedValueOnce({
+    (global.fetch as ReturnType<typeof vi.fn>).mockResolvedValueOnce({
       ok: true,
       json: () => mockLayout,
     });
@@ -108,7 +108,7 @@ describe("useCreateLayout", (): void => {
   });
 
   it("should handle creation errors", async (): Promise<void> => {
-    (global.fetch as any).mockRejectedValueOnce(new Error("API Error"));
+    (global.fetch as ReturnType<typeof vi.fn>).mockRejectedValueOnce(new Error("API Error"));
 
     const { result } = renderHook(() => useCreateLayout(), {
       wrapper: createWrapper(),
@@ -138,7 +138,7 @@ describe("useUpdateLayout", (): void => {
       layout: [{ i: "widget-1", x: 0, y: 0, w: 2, h: 2 }],
     };
 
-    (global.fetch as any).mockResolvedValueOnce({
+    (global.fetch as ReturnType<typeof vi.fn>).mockResolvedValueOnce({
       ok: true,
       json: () => mockLayout,
     });
@@ -160,7 +160,7 @@ describe("useUpdateLayout", (): void => {
   });
 
   it("should handle update errors", async (): Promise<void> => {
-    (global.fetch as any).mockRejectedValueOnce(new Error("API Error"));
+    (global.fetch as ReturnType<typeof vi.fn>).mockRejectedValueOnce(new Error("API Error"));
 
     const { result } = renderHook(() => useUpdateLayout(), {
       wrapper: createWrapper(),
@@ -183,7 +183,7 @@ describe("useDeleteLayout", (): void => {
   });
 
   it("should delete a layout", async (): Promise<void> => {
-    (global.fetch as any).mockResolvedValueOnce({
+    (global.fetch as ReturnType<typeof vi.fn>).mockResolvedValueOnce({
       ok: true,
       json: () => ({ success: true }),
     });
@@ -200,7 +200,7 @@ describe("useDeleteLayout", (): void => {
   });
 
   it("should handle deletion errors", async (): Promise<void> => {
-    (global.fetch as any).mockRejectedValueOnce(new Error("API Error"));
+    (global.fetch as ReturnType<typeof vi.fn>).mockRejectedValueOnce(new Error("API Error"));
 
     const { result } = renderHook(() => useDeleteLayout(), {
       wrapper: createWrapper(),
diff --git a/apps/web/src/hooks/useWebSocket.test.tsx b/apps/web/src/hooks/useWebSocket.test.tsx
index 4abefa8..4de3290 100644
--- a/apps/web/src/hooks/useWebSocket.test.tsx
+++ b/apps/web/src/hooks/useWebSocket.test.tsx
@@ -17,14 +17,14 @@ describe("useWebSocket", (): void => {
     mockSocket = {
       on: vi.fn((event: string, handler: (...args: unknown[]) => void) => {
         eventHandlers[event] = handler;
-        return mockSocket as Socket;
+        return mockSocket;
       }) as unknown as Socket["on"],
       off: vi.fn((event?: string) => {
         if (event && Object.hasOwn(eventHandlers, event)) {
           // eslint-disable-next-line @typescript-eslint/no-dynamic-delete
           delete eventHandlers[event];
         }
-        return mockSocket as Socket;
+        return mockSocket;
       }) as unknown as Socket["off"],
       connect: vi.fn(),
       disconnect: vi.fn(),
diff --git a/apps/web/src/lib/api/client.ts b/apps/web/src/lib/api/client.ts
index f215e84..f1c2eb1 100644
--- a/apps/web/src/lib/api/client.ts
+++ b/apps/web/src/lib/api/client.ts
@@ -40,7 +40,7 @@ export async function apiRequest<T>(endpoint: string, options: RequestInit = {})
       (): ApiError => ({
         code: "UNKNOWN_ERROR",
         message: response.statusText || "An unknown error occurred",
-      }),
+      })
     );
 
     throw new Error(error.message);
diff --git a/apps/web/src/lib/auth/auth-context.tsx b/apps/web/src/lib/auth/auth-context.tsx
index 850b68c..8d9c628 100644
--- a/apps/web/src/lib/auth/auth-context.tsx
+++ b/apps/web/src/lib/auth/auth-context.tsx
@@ -32,7 +32,7 @@ export function AuthProvider({ children }: { children: ReactNode }) {
   const signOut = useCallback(async () => {
     try {
       await apiPost("/auth/sign-out");
-    } catch (_error) {
+    } catch (error) {
       console.error("Sign out error:", error);
     } finally {
       setUser(null);
diff --git a/apps/web/src/lib/hooks/useLayout.ts b/apps/web/src/lib/hooks/useLayout.ts
index 75adb29..aa3a6e0 100644
--- a/apps/web/src/lib/hooks/useLayout.ts
+++ b/apps/web/src/lib/hooks/useLayout.ts
@@ -35,7 +35,7 @@ export function useLayout() {
       if (storedLayoutId) {
         setCurrentLayoutId(storedLayoutId);
       }
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to load layouts from localStorage:", error);
     } finally {
       setIsLoading(false);
@@ -48,7 +48,7 @@ export function useLayout() {
       try {
         localStorage.setItem(STORAGE_KEY, JSON.stringify(layouts));
         localStorage.setItem(`${STORAGE_KEY}-current`, currentLayoutId);
-      } catch (_error) {
+      } catch (error) {
         console.error("Failed to save layouts to localStorage:", error);
       }
     }
@@ -215,7 +215,7 @@ export function useWorkspaceId(): string | null {
       if (stored) {
         setWorkspaceId(stored);
       }
-    } catch (_error) {
+    } catch (error) {
       console.error("Failed to load workspace ID from localStorage:", error);
     }
   }, []);
diff --git a/apps/web/src/providers/ThemeProvider.tsx b/apps/web/src/providers/ThemeProvider.tsx
index c6eaa96..d189b4f 100644
--- a/apps/web/src/providers/ThemeProvider.tsx
+++ b/apps/web/src/providers/ThemeProvider.tsx
@@ -92,8 +92,12 @@ export function ThemeProvider({ children, defaultTheme = "system" }: ThemeProvid
         value={{
           theme: defaultTheme,
           resolvedTheme: "dark",
-          setTheme: (): void => {},
-          toggleTheme: (): void => {},
+          setTheme: (): void => {
+            // No-op during SSR
+          },
+          toggleTheme: (): void => {
+            // No-op during SSR
+          },
         }}
       >
         {children}
diff --git a/apps/web/src/test/setup.d.ts b/apps/web/src/test/setup.d.ts
new file mode 100644
index 0000000..9595cfc
--- /dev/null
+++ b/apps/web/src/test/setup.d.ts
@@ -0,0 +1,13 @@
+/**
+ * Type declarations for test environment
+ */
+
+import type { TestingLibraryMatchers } from "@testing-library/jest-dom/matchers";
+import type { Assertion, AsymmetricMatchersContaining } from "vitest";
+
+declare module "vitest" {
+  // eslint-disable-next-line @typescript-eslint/no-empty-object-type
+  interface Assertion<T = unknown> extends TestingLibraryMatchers<T, void> {}
+  // eslint-disable-next-line @typescript-eslint/no-empty-object-type
+  interface AsymmetricMatchersContaining extends TestingLibraryMatchers<unknown, void> {}
+}
diff --git a/apps/web/tsconfig.json b/apps/web/tsconfig.json
index 7770ae4..a0fc583 100644
--- a/apps/web/tsconfig.json
+++ b/apps/web/tsconfig.json
@@ -8,6 +8,6 @@
     "noUnusedLocals": false,
     "noUnusedParameters": false
   },
-  "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],
+  "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts", "src/test/setup.d.ts"],
   "exclude": ["node_modules"]
 }