diff --git a/apps/api/src/__tests__/Database.spec.ts b/apps/api/src/__tests__/Database.spec.ts
new file mode 100644
index 0000000..158accb
--- /dev/null
+++ b/apps/api/src/__tests__/Database.spec.ts
@@ -0,0 +1,70 @@
+import { Database } from '../modules/Database';
+import { QueryOperators } from '@zoneless/shared-types';
+
+describe('Database', () => {
+  let db: Database;
+  let find: jest.Mock;
+
+  beforeEach(() => {
+    db = new Database();
+    const query = {
+      sort: jest.fn().mockReturnThis(),
+      limit: jest.fn().mockReturnThis(),
+      lean: jest.fn().mockReturnThis(),
+      exec: jest.fn().mockResolvedValue([]),
+    };
+    find = jest.fn().mockReturnValue(query);
+    jest
+      .spyOn(db as unknown as { GetModel: () => unknown }, 'GetModel')
+      .mockReturnValue({ find });
+  });
+
+  describe('Query', () => {
+    it('should combine range conditions on the same field', async () => {
+      await db.Query({
+        collection: 'Charges',
+        method: 'READ',
+        parameters: [
+          { key: 'created', operator: QueryOperators['>='], value: 1010 },
+          { key: 'created', operator: QueryOperators['<='], value: 1020 },
+          { key: 'account', operator: QueryOperators['=='], value: 'acct_1' },
+        ],
+      });
+
+      expect(find).toHaveBeenCalledWith({
+        created: { $gte: 1010, $lte: 1020 },
+        account: 'acct_1',
+      });
+    });
+
+    it('should keep range conditions when paginating with startAfter', async () => {
+      await db.Query({
+        collection: 'Charges',
+        method: 'READ',
+        parameters: [
+          { key: 'created', operator: QueryOperators['>'], value: 1000 },
+          { key: 'created', operator: QueryOperators['<'], value: 1030 },
+        ],
+        orderBy: [{ key: 'created', direction: 'desc' }],
+        startAfter: 1025,
+      });
+
+      expect(find).toHaveBeenLastCalledWith({
+        created: { $gt: 1000, $lt: 1025 },
+      });
+    });
+
+    it('should replace an equality condition on the same field', async () => {
+      await db.Query({
+        collection: 'Charges',
+        method: 'READ',
+        parameters: [
+          { key: 'status', operator: QueryOperators['=='], value: 'pending' },
+          { key: 'status', operator: QueryOperators['=='], value: 'succeeded' },
+        ],
+      });
+
+      expect(find).toHaveBeenCalledWith({ status: 'succeeded' });
+    });
+  });
+});
diff --git a/apps/api/src/modules/Database.ts b/apps/api/src/modules/Database.ts
index 7880426..ad594a4 100644
--- a/apps/api/src/modules/Database.ts
+++ b/apps/api/src/modules/Database.ts
@@ -257,15 +257,19 @@ export class Database {
     const model = this.GetModel(options.collection);
 
     // Build MongoDB filter from parameters
-    let filter: Record<string, unknown> = {};
+    const filter: Record<string, unknown> = {};
     if (options.parameters) {
       for (const param of options.parameters) {
-        const paramFilter = this.BuildFilter(
+        const condition = this.BuildFilter(
           param.key,
           param.operator,
           param.value
-        );
-        filter = { ...filter, ...paramFilter };
+        )[param.key];
+        const existing = filter[param.key];
+        filter[param.key] =
+          this.IsOperatorObject(existing) && this.IsOperatorObject(condition)
+            ? { ...existing, ...condition }
+            : condition;
       }
     }
 
@@ -435,6 +439,15 @@ export class Database {
     }
   }
 
+  private IsOperatorObject(value: unknown): value is Record<string, unknown> {
+    return (
+      typeof value === 'object' &&
+      value !== null &&
+      !Array.isArray(value) &&
+      Object.keys(value).every((key) => key.startsWith('$'))
+    );
+  }
+
   /**
    * Pre-create all known collections and their indexes so that concurrent
    * requests on a fresh database don't race to implicitly create them.