diff --git a/app/src/app/api/compositions/route.ts b/app/src/app/api/compositions/route.ts
index 3688b99..83411d3 100644
--- a/app/src/app/api/compositions/route.ts
+++ b/app/src/app/api/compositions/route.ts
@@ -9,7 +9,10 @@ export async function GET(request: NextRequest) {
   const projectId = request.nextUrl.searchParams.get('project_id');
   if (!projectId)
     return NextResponse.json({ success: false, error: 'project_id required' }, { status: 400 });
-  if (!(await ownsProject(supabase, projectId, userId))) {
+  const ownership = await ownsProject(supabase, projectId, userId);
+  if (ownership.error)
+    return NextResponse.json({ success: false, error: ownership.error }, { status: 500 });
+  if (!ownership.owns) {
     return NextResponse.json({ success: false, error: 'Not found' }, { status: 404 });
   }
 
@@ -37,7 +40,10 @@ export async function POST(request: NextRequest) {
     );
   }
 
-  if (!(await ownsProject(supabase, parsed.data.project_id, userId))) {
+  const ownership = await ownsProject(supabase, parsed.data.project_id, userId);
+  if (ownership.error)
+    return NextResponse.json({ success: false, error: ownership.error }, { status: 500 });
+  if (!ownership.owns) {
     return NextResponse.json({ success: false, error: 'Not found' }, { status: 404 });
   }
 
diff --git a/app/src/app/api/figures/[id]/route.ts b/app/src/app/api/figures/[id]/route.ts
index 9b48e23..3a30d30 100644
--- a/app/src/app/api/figures/[id]/route.ts
+++ b/app/src/app/api/figures/[id]/route.ts
@@ -17,7 +17,10 @@ export async function PATCH(request: NextRequest, context: RouteContext) {
       { status: 400 },
     );
   }
-  if (!(await ownsFigure(supabase, id, userId))) {
+  const ownership = await ownsFigure(supabase, id, userId);
+  if (ownership.error)
+    return NextResponse.json({ success: false, error: ownership.error }, { status: 500 });
+  if (!ownership.owns) {
     return NextResponse.json({ success: false, error: 'Not found' }, { status: 404 });
   }
 
@@ -36,7 +39,10 @@ export async function DELETE(_request: NextRequest, context: RouteContext) {
   const { id } = await context.params;
   const { supabase, userId } = await getApiClient();
 
-  if (!(await ownsFigure(supabase, id, userId))) {
+  const ownership = await ownsFigure(supabase, id, userId);
+  if (ownership.error)
+    return NextResponse.json({ success: false, error: ownership.error }, { status: 500 });
+  if (!ownership.owns) {
     return NextResponse.json({ success: false, error: 'Not found' }, { status: 404 });
   }
 
diff --git a/app/src/app/api/figures/route.ts b/app/src/app/api/figures/route.ts
index 7678c8e..a8bc449 100644
--- a/app/src/app/api/figures/route.ts
+++ b/app/src/app/api/figures/route.ts
@@ -9,7 +9,10 @@ export async function GET(request: NextRequest) {
   const projectId = request.nextUrl.searchParams.get('project_id');
   if (!projectId)
     return NextResponse.json({ success: false, error: 'project_id required' }, { status: 400 });
-  if (!(await ownsProject(supabase, projectId, userId))) {
+  const ownership = await ownsProject(supabase, projectId, userId);
+  if (ownership.error)
+    return NextResponse.json({ success: false, error: ownership.error }, { status: 500 });
+  if (!ownership.owns) {
     return NextResponse.json({ success: false, error: 'Not found' }, { status: 404 });
   }
 
@@ -34,7 +37,10 @@ export async function POST(request: NextRequest) {
       { status: 400 },
     );
   }
-  if (!(await ownsProject(supabase, parsed.data.project_id, userId))) {
+  const ownership = await ownsProject(supabase, parsed.data.project_id, userId);
+  if (ownership.error)
+    return NextResponse.json({ success: false, error: ownership.error }, { status: 500 });
+  if (!ownership.owns) {
     return NextResponse.json({ success: false, error: 'Not found' }, { status: 404 });
   }
 
diff --git a/app/src/app/api/surfaces/route.ts b/app/src/app/api/surfaces/route.ts
index 1168ba5..df00243 100644
--- a/app/src/app/api/surfaces/route.ts
+++ b/app/src/app/api/surfaces/route.ts
@@ -9,7 +9,10 @@ export async function GET(request: NextRequest) {
   const projectId = request.nextUrl.searchParams.get('project_id');
   if (!projectId)
     return NextResponse.json({ success: false, error: 'project_id required' }, { status: 400 });
-  if (!(await ownsProject(supabase, projectId, userId))) {
+  const ownership = await ownsProject(supabase, projectId, userId);
+  if (ownership.error)
+    return NextResponse.json({ success: false, error: ownership.error }, { status: 500 });
+  if (!ownership.owns) {
     return NextResponse.json({ success: false, error: 'Not found' }, { status: 404 });
   }
 
@@ -35,7 +38,10 @@ export async function POST(request: NextRequest) {
     );
   }
 
-  if (!(await ownsProject(supabase, parsed.data.project_id, userId))) {
+  const ownership = await ownsProject(supabase, parsed.data.project_id, userId);
+  if (ownership.error)
+    return NextResponse.json({ success: false, error: ownership.error }, { status: 500 });
+  if (!ownership.owns) {
     return NextResponse.json({ success: false, error: 'Not found' }, { status: 404 });
   }
 
diff --git a/app/src/lib/api/ownership.test.ts b/app/src/lib/api/ownership.test.ts
index bd99bc6..1aed7a0 100644
--- a/app/src/lib/api/ownership.test.ts
+++ b/app/src/lib/api/ownership.test.ts
@@ -12,7 +12,7 @@ import { ownsProject, ownsFigure } from './ownership';
 type Row = Record<string, string>;
 type SupabaseArg = Parameters<typeof ownsProject>[0];
 
-function fakeSupabase(tables: Record<string, Row[]>): SupabaseArg {
+function fakeSupabase(tables: Record<string, Row[]>, failTable?: string): SupabaseArg {
   const client = {
     from(table: string) {
       const filters: Row = {};
@@ -23,6 +23,9 @@ function fakeSupabase(tables: Record<string, Row[]>): SupabaseArg {
           return builder;
         },
         maybeSingle: async () => {
+          if (table === failTable) {
+            return { data: null, error: { message: `${table} query failed` } };
+          }
           const rows = tables[table] ?? [];
           const match = rows.find((row) =>
             Object.entries(filters).every(([column, value]) => row[column] === value),
@@ -46,34 +49,67 @@ const db = {
 
 describe('ownsProject', () => {
   it('accepts the owner', async () => {
-    expect(await ownsProject(fakeSupabase(db), 'project-a', OWNER)).toBe(true);
+    expect(await ownsProject(fakeSupabase(db), 'project-a', OWNER)).toEqual({
+      owns: true,
+      error: null,
+    });
   });
 
   it('refuses someone else holding a real project id', async () => {
-    expect(await ownsProject(fakeSupabase(db), 'project-a', STRANGER)).toBe(false);
+    expect(await ownsProject(fakeSupabase(db), 'project-a', STRANGER)).toEqual({
+      owns: false,
+      error: null,
+    });
   });
 
   it('refuses an id that does not exist', async () => {
-    expect(await ownsProject(fakeSupabase(db), 'project-nope', OWNER)).toBe(false);
+    expect(await ownsProject(fakeSupabase(db), 'project-nope', OWNER)).toEqual({
+      owns: false,
+      error: null,
+    });
+  });
+
+  it('surfaces a query failure instead of silently reporting not-owned', async () => {
+    const result = await ownsProject(fakeSupabase(db, 'projects'), 'project-a', OWNER);
+    expect(result.owns).toBe(false);
+    expect(result.error).not.toBeNull();
   });
 });
 
 describe('ownsFigure', () => {
   it("accepts a figure inside the caller's own project", async () => {
-    expect(await ownsFigure(fakeSupabase(db), 'figure-a', OWNER)).toBe(true);
+    expect(await ownsFigure(fakeSupabase(db), 'figure-a', OWNER)).toEqual({
+      owns: true,
+      error: null,
+    });
   });
 
   it("refuses a figure inside somebody else's project", async () => {
-    expect(await ownsFigure(fakeSupabase(db), 'figure-a', STRANGER)).toBe(false);
+    expect(await ownsFigure(fakeSupabase(db), 'figure-a', STRANGER)).toEqual({
+      owns: false,
+      error: null,
+    });
   });
 
   it('refuses a figure that does not exist', async () => {
-    expect(await ownsFigure(fakeSupabase(db), 'figure-nope', OWNER)).toBe(false);
+    expect(await ownsFigure(fakeSupabase(db), 'figure-nope', OWNER)).toEqual({
+      owns: false,
+      error: null,
+    });
   });
 
   it('refuses an orphaned figure rather than defaulting to allow', async () => {
     const orphan = { projects: db.projects, figures: [{ id: 'figure-orphan' }] };
-    expect(await ownsFigure(fakeSupabase(orphan), 'figure-orphan', OWNER)).toBe(false);
+    expect(await ownsFigure(fakeSupabase(orphan), 'figure-orphan', OWNER)).toEqual({
+      owns: false,
+      error: null,
+    });
+  });
+
+  it('surfaces a figure-query failure instead of silently reporting not-owned', async () => {
+    const result = await ownsFigure(fakeSupabase(db, 'figures'), 'figure-a', OWNER);
+    expect(result.owns).toBe(false);
+    expect(result.error).not.toBeNull();
   });
 });
 
diff --git a/app/src/lib/api/ownership.ts b/app/src/lib/api/ownership.ts
index eb76a04..855ac8d 100644
--- a/app/src/lib/api/ownership.ts
+++ b/app/src/lib/api/ownership.ts
@@ -15,32 +15,36 @@ import type { getApiClient } from '@/lib/supabase/api-client';
 
 type ApiSupabase = Awaited<ReturnType<typeof getApiClient>>['supabase'];
 
+export type OwnershipResult = { owns: boolean; error: string | null };
+
 export async function ownsProject(
   supabase: ApiSupabase,
   projectId: string,
   userId: string,
-): Promise<boolean> {
-  const { data } = await supabase
+): Promise<OwnershipResult> {
+  const { data, error } = await supabase
     .from('projects')
     .select('id')
     .eq('id', projectId)
     .eq('user_id', userId)
     .maybeSingle();
 
-  return Boolean(data);
+  if (error) return { owns: false, error: error.message };
+  return { owns: Boolean(data), error: null };
 }
 
 export async function ownsFigure(
   supabase: ApiSupabase,
   figureId: string,
   userId: string,
-): Promise<boolean> {
-  const { data } = await supabase
+): Promise<OwnershipResult> {
+  const { data, error } = await supabase
     .from('figures')
     .select('project_id')
     .eq('id', figureId)
     .maybeSingle();
 
-  if (!data?.project_id) return false;
+  if (error) return { owns: false, error: error.message };
+  if (!data?.project_id) return { owns: false, error: null };
   return ownsProject(supabase, data.project_id, userId);
 }