diff --git a/backend/petshop-api.postman_collection.json b/backend/petshop-api.postman_collection.json
index 1068f4e0..3b36221b 100644
--- a/backend/petshop-api.postman_collection.json
+++ b/backend/petshop-api.postman_collection.json
@@ -2,7 +2,7 @@
   "info": {
     "name": "PetShop  Complete Collection",
     "_postman_id": "petshop-api-complete-v1",
-    "description": "Complete API collection with all 95+ verified endpoints",
+    "description": "Complete API collection for all backend endpoints",
     "schema": "https://schema.getpostman.com/json/collection/v2.1.0/collection.json"
   },
   "variable": [
@@ -124,7 +124,11 @@
     },
     {
       "key": "adoptedPetId",
-      "value": "4"
+      "value": "15"
+    },
+    {
+      "key": "employeeId",
+      "value": ""
     }
   ],
   "item": [
@@ -221,6 +225,7 @@
                   "});",
                   "var jsonData = pm.response.json();",
                   "if (jsonData.id !== undefined) pm.collectionVariables.set('userId', jsonData.id);",
+                  "if (jsonData.id !== undefined) pm.collectionVariables.set('customerId', jsonData.id);",
                   "if (jsonData.token) pm.collectionVariables.set('customerToken', jsonData.token);"
                 ]
               }
@@ -659,6 +664,37 @@
             }
           ]
         },
+        {
+          "name": "Dropdown: Pet Species",
+          "request": {
+            "method": "GET",
+            "url": "{{baseUrl}}/api/v1/dropdowns/pet-species",
+            "header": [
+              {
+                "key": "Content-Type",
+                "value": "application/json"
+              },
+              {
+                "key": "Authorization",
+                "value": "Bearer {{staffToken}}",
+                "type": "text"
+              }
+            ]
+          },
+          "event": [
+            {
+              "listen": "test",
+              "script": {
+                "type": "text/javascript",
+                "exec": [
+                  "pm.test('Status code is 200', function () {",
+                  "    pm.response.to.have.status(200);",
+                  "});"
+                ]
+              }
+            }
+          ]
+        },
         {
           "name": "Create Pet",
           "request": {
@@ -723,7 +759,7 @@
             ],
             "body": {
               "mode": "raw",
-              "raw": "{\n  \"petName\": \"Postman Pet Updated\",\n  \"petSpecies\": \"Dog\",\n  \"petBreed\": \"Mixed\",\n  \"petAge\": 3,\n  \"petStatus\": \"Owned\",\n  \"petPrice\": 375.00,\n  \"customerId\": 1\n}",
+              "raw": "{\n  \"petName\": \"Postman Pet Updated\",\n  \"petSpecies\": \"Dog\",\n  \"petBreed\": \"Mixed\",\n  \"petAge\": 3,\n  \"petStatus\": \"Owned\",\n  \"petPrice\": 375.00,\n  \"customerId\": {{customerId}}\n}",
               "options": {
                 "raw": {
                   "language": "json"
@@ -1475,13 +1511,13 @@
               },
               {
                 "key": "Authorization",
-                "value": "Bearer {{staffToken}}",
+                "value": "Bearer {{adminToken}}",
                 "type": "text"
               }
             ],
             "body": {
               "mode": "raw",
-              "raw": "{\n  \"storeId\": 1,\n  \"paymentMethod\": \"Card\",\n  \"customerId\": 1,\n  \"items\": [\n    {\n      \"prodId\": 1,\n      \"quantity\": 2\n    },\n    {\n      \"prodId\": 2,\n      \"quantity\": 1\n    }\n  ],\n  \"isRefund\": false\n}"
+              "raw": "{\n  \"storeId\": {{storeId}},\n  \"paymentMethod\": \"Card\",\n  \"customerId\": {{customerId}},\n  \"items\": [\n    {\n      \"prodId\": 7,\n      \"quantity\": 2\n    },\n    {\n      \"prodId\": 8,\n      \"quantity\": 1\n    }\n  ],\n  \"isRefund\": false\n}"
             }
           },
           "event": [
@@ -1889,6 +1925,37 @@
             }
           ]
         },
+        {
+          "name": "Dropdown: Product Categories",
+          "request": {
+            "method": "GET",
+            "url": "{{baseUrl}}/api/v1/dropdowns/product-categories",
+            "header": [
+              {
+                "key": "Content-Type",
+                "value": "application/json"
+              },
+              {
+                "key": "Authorization",
+                "value": "Bearer {{staffToken}}",
+                "type": "text"
+              }
+            ]
+          },
+          "event": [
+            {
+              "listen": "test",
+              "script": {
+                "type": "text/javascript",
+                "exec": [
+                  "pm.test('Status code is 200', function () {",
+                  "    pm.response.to.have.status(200);",
+                  "});"
+                ]
+              }
+            }
+          ]
+        },
         {
           "name": "Create Category",
           "request": {
@@ -2119,7 +2186,7 @@
           "name": "Check Appointment Availability",
           "request": {
             "method": "GET",
-            "url": "{{baseUrl}}/api/v1/appointments/availability?storeId=1&serviceId=1&date=2026-12-20",
+            "url": "{{baseUrl}}/api/v1/appointments/availability?storeId={{storeId}}&serviceId={{serviceId}}&date=2026-12-20",
             "header": [
               {
                 "key": "Content-Type",
@@ -2150,7 +2217,55 @@
           "name": "List Appointments",
           "request": {
             "method": "GET",
-            "url": "{{baseUrl}}/api/v1/appointments",
+            "url": {
+              "raw": "{{baseUrl}}/api/v1/appointments",
+              "host": [
+                "{{baseUrl}}"
+              ],
+              "path": [
+                "api",
+                "v1",
+                "appointments"
+              ],
+              "query": [
+                {
+                  "key": "q",
+                  "value": "",
+                  "disabled": true,
+                  "description": "optional"
+                },
+                {
+                  "key": "storeId",
+                  "value": "1",
+                  "disabled": true,
+                  "description": "optional"
+                },
+                {
+                  "key": "status",
+                  "value": "Booked",
+                  "disabled": true,
+                  "description": "optional"
+                },
+                {
+                  "key": "date",
+                  "value": "2026-12-20",
+                  "disabled": true,
+                  "description": "optional"
+                },
+                {
+                  "key": "customerId",
+                  "value": "1",
+                  "disabled": true,
+                  "description": "optional"
+                },
+                {
+                  "key": "employeeId",
+                  "value": "1",
+                  "disabled": true,
+                  "description": "optional"
+                }
+              ]
+            },
             "header": [
               {
                 "key": "Content-Type",
@@ -2226,7 +2341,7 @@
             ],
             "body": {
               "mode": "raw",
-              "raw": "{\n  \"customerId\": 1,\n  \"storeId\": 1,\n  \"serviceId\": 1,\n  \"appointmentDate\": \"2026-12-20\",\n  \"appointmentTime\": \"10:00:00\",\n  \"appointmentStatus\": \"Booked\",\n  \"petIds\": [\n    1\n  ],\n  \"employeeId\": 1\n}",
+              "raw": "{\n  \"customerId\": {{customerId}},\n  \"storeId\": {{storeId}},\n  \"serviceId\": {{serviceId}},\n  \"appointmentDate\": \"2026-12-20\",\n  \"appointmentTime\": \"10:00:00\",\n  \"appointmentStatus\": \"Booked\",\n  \"petId\": {{petId}}\n}",
               "options": {
                 "raw": {
                   "language": "json"
@@ -2268,7 +2383,7 @@
             ],
             "body": {
               "mode": "raw",
-              "raw": "{\n  \"customerId\": 1,\n  \"storeId\": 1,\n  \"serviceId\": 1,\n  \"appointmentDate\": \"2026-12-20\",\n  \"appointmentTime\": \"11:00:00\",\n  \"appointmentStatus\": \"Booked\",\n  \"petIds\": [\n    1\n  ],\n  \"employeeId\": 1\n}",
+              "raw": "{\n  \"customerId\": {{customerId}},\n  \"storeId\": {{storeId}},\n  \"serviceId\": {{serviceId}},\n  \"appointmentDate\": \"2026-12-20\",\n  \"appointmentTime\": \"11:00:00\",\n  \"appointmentStatus\": \"Booked\",\n  \"petId\": {{petId}}\n}",
               "options": {
                 "raw": {
                   "language": "json"
@@ -2472,7 +2587,7 @@
             ],
             "body": {
               "mode": "raw",
-              "raw": "{\n  \"petId\": 3,\n  \"customerId\": 1,\n  \"adoptionDate\": \"2026-12-21\",\n  \"adoptionStatus\": \"Pending\",\n  \"employeeId\": 1\n}",
+              "raw": "{\n  \"petId\": {{adoptedPetId}},\n  \"customerId\": {{customerId}},\n  \"adoptionDate\": \"2026-12-21\",\n  \"adoptionStatus\": \"Pending\",\n  \"sourceStoreId\": {{storeId}}\n}",
               "options": {
                 "raw": {
                   "language": "json"
@@ -2514,7 +2629,7 @@
             ],
             "body": {
               "mode": "raw",
-              "raw": "{\n  \"petId\": 3,\n  \"customerId\": 1,\n  \"adoptionDate\": \"2026-12-22\",\n  \"adoptionStatus\": \"Completed\",\n  \"employeeId\": 1\n}",
+              "raw": "{\n  \"petId\": {{adoptedPetId}},\n  \"customerId\": {{customerId}},\n  \"adoptionDate\": \"2026-12-22\",\n  \"adoptionStatus\": \"Completed\",\n  \"sourceStoreId\": {{storeId}}\n}",
               "options": {
                 "raw": {
                   "language": "json"
@@ -2625,7 +2740,7 @@
             ],
             "body": {
               "mode": "raw",
-              "raw": "{\n  \"saleId\": 1,\n  \"reason\": \"Defective product\"\n}",
+              "raw": "{\n  \"saleId\": {{saleId}},\n  \"reason\": \"Defective product\",\n  \"items\": [\n    {\n      \"prodId\": 7,\n      \"quantity\": 1\n    }\n  ]\n}",
               "options": {
                 "raw": {
                   "language": "json"
@@ -3104,6 +3219,46 @@
               }
             }
           ]
+        },
+        {
+          "name": "Update Conversation",
+          "request": {
+            "method": "PUT",
+            "url": "{{baseUrl}}/api/v1/chat/conversations/{{conversationId}}",
+            "header": [
+              {
+                "key": "Content-Type",
+                "value": "application/json"
+              },
+              {
+                "key": "Authorization",
+                "value": "Bearer {{staffToken}}",
+                "type": "text"
+              }
+            ],
+            "body": {
+              "mode": "raw",
+              "raw": "{\n  \"status\": \"CLOSED\"\n}",
+              "options": {
+                "raw": {
+                  "language": "json"
+                }
+              }
+            }
+          },
+          "event": [
+            {
+              "listen": "test",
+              "script": {
+                "type": "text/javascript",
+                "exec": [
+                  "pm.test('Status code is 200', function () {",
+                  "    pm.response.to.have.status(200);",
+                  "});"
+                ]
+              }
+            }
+          ]
         }
       ]
     },
@@ -3762,6 +3917,186 @@
         }
       ]
     },
+    {
+      "name": "Employees",
+      "item": [
+        {
+          "name": "List Employees",
+          "request": {
+            "method": "GET",
+            "url": "{{baseUrl}}/api/v1/employees",
+            "header": [
+              {
+                "key": "Content-Type",
+                "value": "application/json"
+              },
+              {
+                "key": "Authorization",
+                "value": "Bearer {{adminToken}}",
+                "type": "text"
+              }
+            ]
+          },
+          "event": [
+            {
+              "listen": "test",
+              "script": {
+                "type": "text/javascript",
+                "exec": [
+                  "pm.test('Status code is 200', function () {",
+                  "    pm.response.to.have.status(200);",
+                  "});"
+                ]
+              }
+            }
+          ]
+        },
+        {
+          "name": "Get Employee by ID",
+          "request": {
+            "method": "GET",
+            "url": "{{baseUrl}}/api/v1/employees/{{employeeId}}",
+            "header": [
+              {
+                "key": "Content-Type",
+                "value": "application/json"
+              },
+              {
+                "key": "Authorization",
+                "value": "Bearer {{adminToken}}",
+                "type": "text"
+              }
+            ]
+          },
+          "event": [
+            {
+              "listen": "test",
+              "script": {
+                "type": "text/javascript",
+                "exec": [
+                  "pm.test('Status code is 200', function () {",
+                  "    pm.response.to.have.status(200);",
+                  "});"
+                ]
+              }
+            }
+          ]
+        },
+        {
+          "name": "Create Employee",
+          "request": {
+            "method": "POST",
+            "url": "{{baseUrl}}/api/v1/employees",
+            "header": [
+              {
+                "key": "Content-Type",
+                "value": "application/json"
+              },
+              {
+                "key": "Authorization",
+                "value": "Bearer {{adminToken}}",
+                "type": "text"
+              }
+            ],
+            "body": {
+              "mode": "raw",
+              "raw": "{\n  \"username\": \"employee{{$timestamp}}\",\n  \"password\": \"employee123\",\n  \"firstName\": \"Jane\",\n  \"lastName\": \"Smith\",\n  \"email\": \"employee{{$timestamp}}@petshop.com\",\n  \"phone\": \"403-555-0200\",\n  \"role\": \"STAFF\",\n  \"staffRole\": \"GROOMER\",\n  \"primaryStoreId\": 1,\n  \"active\": true\n}",
+              "options": {
+                "raw": {
+                  "language": "json"
+                }
+              }
+            }
+          },
+          "event": [
+            {
+              "listen": "test",
+              "script": {
+                "type": "text/javascript",
+                "exec": [
+                  "pm.test('Status code is 201', function () {",
+                  "    pm.response.to.have.status(201);",
+                  "});",
+                  "var jsonData = pm.response.json();",
+                  "if (jsonData.id) pm.collectionVariables.set('employeeId', jsonData.id);"
+                ]
+              }
+            }
+          ]
+        },
+        {
+          "name": "Update Employee",
+          "request": {
+            "method": "PUT",
+            "url": "{{baseUrl}}/api/v1/employees/{{employeeId}}",
+            "header": [
+              {
+                "key": "Content-Type",
+                "value": "application/json"
+              },
+              {
+                "key": "Authorization",
+                "value": "Bearer {{adminToken}}",
+                "type": "text"
+              }
+            ],
+            "body": {
+              "mode": "raw",
+              "raw": "{\n  \"firstName\": \"Jane\",\n  \"lastName\": \"Smith\",\n  \"email\": \"employee.updated@petshop.com\",\n  \"phone\": \"403-555-0201\",\n  \"role\": \"STAFF\",\n  \"staffRole\": \"VET\",\n  \"primaryStoreId\": 1,\n  \"active\": true\n}",
+              "options": {
+                "raw": {
+                  "language": "json"
+                }
+              }
+            }
+          },
+          "event": [
+            {
+              "listen": "test",
+              "script": {
+                "type": "text/javascript",
+                "exec": [
+                  "pm.test('Status code is 200', function () {",
+                  "    pm.response.to.have.status(200);",
+                  "});"
+                ]
+              }
+            }
+          ]
+        },
+        {
+          "name": "Delete Employee",
+          "request": {
+            "method": "DELETE",
+            "url": "{{baseUrl}}/api/v1/employees/{{employeeId}}",
+            "header": [
+              {
+                "key": "Content-Type",
+                "value": "application/json"
+              },
+              {
+                "key": "Authorization",
+                "value": "Bearer {{adminToken}}",
+                "type": "text"
+              }
+            ]
+          },
+          "event": [
+            {
+              "listen": "test",
+              "script": {
+                "type": "text/javascript",
+                "exec": [
+                  "pm.test('Status code is 204', function () {",
+                  "    pm.response.to.have.status(204);",
+                  "});"
+                ]
+              }
+            }
+          ]
+        }
+      ]
+    },
     {
       "name": "Stores",
       "item": [
@@ -4119,7 +4454,31 @@
           "name": "List Inventory",
           "request": {
             "method": "GET",
-            "url": "{{baseUrl}}/api/v1/inventory",
+            "url": {
+              "raw": "{{baseUrl}}/api/v1/inventory",
+              "host": [
+                "{{baseUrl}}"
+              ],
+              "path": [
+                "api",
+                "v1",
+                "inventory"
+              ],
+              "query": [
+                {
+                  "key": "q",
+                  "value": "",
+                  "disabled": true,
+                  "description": "optional"
+                },
+                {
+                  "key": "storeId",
+                  "value": "1",
+                  "disabled": true,
+                  "description": "optional"
+                }
+              ]
+            },
             "header": [
               {
                 "key": "Content-Type",
@@ -4195,7 +4554,7 @@
             ],
             "body": {
               "mode": "raw",
-              "raw": "{\n  \"prodId\": {{productId}},\n  \"quantity\": 10\n}",
+              "raw": "{\n  \"prodId\": {{productId}},\n  \"quantity\": 10,\n  \"storeId\": {{storeId}}\n}",
               "options": {
                 "raw": {
                   "language": "json"
@@ -4237,7 +4596,7 @@
             ],
             "body": {
               "mode": "raw",
-              "raw": "{\n  \"prodId\": {{productId}},\n  \"quantity\": 12\n}",
+              "raw": "{\n  \"prodId\": {{productId}},\n  \"quantity\": 12,\n  \"storeId\": {{storeId}}\n}",
               "options": {
                 "raw": {
                   "language": "json"
@@ -4308,7 +4667,7 @@
             ],
             "body": {
               "mode": "raw",
-              "raw": "{\n  \"prodId\": {{productId}},\n  \"quantity\": 10\n}",
+              "raw": "{\n  \"prodId\": {{productId}},\n  \"quantity\": 10,\n  \"storeId\": {{storeId}}\n}",
               "options": {
                 "raw": {
                   "language": "json"
@@ -4528,7 +4887,7 @@
               },
               {
                 "key": "Authorization",
-                "value": "Bearer {{staffToken}}",
+                "value": "Bearer {{adminToken}}",
                 "type": "text"
               }
             ]
@@ -4559,7 +4918,7 @@
               },
               {
                 "key": "Authorization",
-                "value": "Bearer {{staffToken}}",
+                "value": "Bearer {{adminToken}}",
                 "type": "text"
               }
             ],
@@ -4622,7 +4981,31 @@
           "name": "List Purchase Orders",
           "request": {
             "method": "GET",
-            "url": "{{baseUrl}}/api/v1/purchase-orders",
+            "url": {
+              "raw": "{{baseUrl}}/api/v1/purchase-orders",
+              "host": [
+                "{{baseUrl}}"
+              ],
+              "path": [
+                "api",
+                "v1",
+                "purchase-orders"
+              ],
+              "query": [
+                {
+                  "key": "q",
+                  "value": "",
+                  "disabled": true,
+                  "description": "optional"
+                },
+                {
+                  "key": "storeId",
+                  "value": "1",
+                  "disabled": true,
+                  "description": "optional"
+                }
+              ]
+            },
             "header": [
               {
                 "key": "Content-Type",
@@ -4689,7 +5072,37 @@
           "name": "List Product Suppliers",
           "request": {
             "method": "GET",
-            "url": "{{baseUrl}}/api/v1/product-suppliers",
+            "url": {
+              "raw": "{{baseUrl}}/api/v1/product-suppliers",
+              "host": [
+                "{{baseUrl}}"
+              ],
+              "path": [
+                "api",
+                "v1",
+                "product-suppliers"
+              ],
+              "query": [
+                {
+                  "key": "q",
+                  "value": "",
+                  "disabled": true,
+                  "description": "optional"
+                },
+                {
+                  "key": "productId",
+                  "value": "{{productId}}",
+                  "disabled": true,
+                  "description": "optional"
+                },
+                {
+                  "key": "supplierId",
+                  "value": "{{supplierId}}",
+                  "disabled": true,
+                  "description": "optional"
+                }
+              ]
+            },
             "header": [
               {
                 "key": "Content-Type",
diff --git a/backend/src/main/java/com/petshop/backend/repository/AdoptionRepository.java b/backend/src/main/java/com/petshop/backend/repository/AdoptionRepository.java
index e3c21776..42f1d578 100644
--- a/backend/src/main/java/com/petshop/backend/repository/AdoptionRepository.java
+++ b/backend/src/main/java/com/petshop/backend/repository/AdoptionRepository.java
@@ -29,9 +29,7 @@ public interface AdoptionRepository extends JpaRepository<Adoption, Long> {
 
     Optional<Adoption> findFirstByPet_IdAndAdoptionStatusOrderByAdoptionDateDesc(Long petId, String adoptionStatus);
 
-    @Query("SELECT CASE WHEN COUNT(a) > 0 THEN true ELSE false END FROM Adoption a WHERE a.pet.id = :petId AND LOWER(a.adoptionStatus) = LOWER(:adoptionStatus) AND a.adoptionId <> :adoptionId")
-    boolean existsByPetPetIdAndAdoptionStatusIgnoreCaseAndAdoptionIdNot(@Param("petId") Long petId, @Param("adoptionStatus") String adoptionStatus, @Param("adoptionId") Long adoptionId);
+    boolean existsByPet_IdAndAdoptionStatusIgnoreCaseAndAdoptionIdNot(Long petId, String adoptionStatus, Long adoptionId);
 
-    @Query("SELECT CASE WHEN COUNT(a) > 0 THEN true ELSE false END FROM Adoption a WHERE a.pet.id = :petId AND LOWER(a.adoptionStatus) = LOWER(:adoptionStatus)")
-    boolean existsByPetPetIdAndAdoptionStatusIgnoreCase(@Param("petId") Long petId, @Param("adoptionStatus") String adoptionStatus);
+    boolean existsByPet_IdAndAdoptionStatusIgnoreCase(Long petId, String adoptionStatus);
 }
diff --git a/backend/src/main/java/com/petshop/backend/service/AdoptionService.java b/backend/src/main/java/com/petshop/backend/service/AdoptionService.java
index ec9ef393..5f76947d 100644
--- a/backend/src/main/java/com/petshop/backend/service/AdoptionService.java
+++ b/backend/src/main/java/com/petshop/backend/service/AdoptionService.java
@@ -199,8 +199,8 @@ public class AdoptionService {
 
     private void validatePetAvailability(Pet pet, Long adoptionId) {
         boolean adoptedElsewhere = adoptionId == null
-                ? adoptionRepository.existsByPetPetIdAndAdoptionStatusIgnoreCase(pet.getPetId(), ADOPTION_STATUS_COMPLETED)
-                : adoptionRepository.existsByPetPetIdAndAdoptionStatusIgnoreCaseAndAdoptionIdNot(pet.getPetId(), ADOPTION_STATUS_COMPLETED, adoptionId);
+                ? adoptionRepository.existsByPet_IdAndAdoptionStatusIgnoreCase(pet.getPetId(), ADOPTION_STATUS_COMPLETED)
+                : adoptionRepository.existsByPet_IdAndAdoptionStatusIgnoreCaseAndAdoptionIdNot(pet.getPetId(), ADOPTION_STATUS_COMPLETED, adoptionId);
         if (adoptedElsewhere) {
             throw new IllegalArgumentException("Selected pet has already been adopted");
         }
@@ -212,7 +212,7 @@ public class AdoptionService {
 
     private void syncPetStatus(Pet pet, String adoptionStatus, Long adoptionId) {
         boolean completedElsewhere = adoptionId != null
-                && adoptionRepository.existsByPetPetIdAndAdoptionStatusIgnoreCaseAndAdoptionIdNot(pet.getPetId(), ADOPTION_STATUS_COMPLETED, adoptionId);
+                && adoptionRepository.existsByPet_IdAndAdoptionStatusIgnoreCaseAndAdoptionIdNot(pet.getPetId(), ADOPTION_STATUS_COMPLETED, adoptionId);
         if (ADOPTION_STATUS_COMPLETED.equalsIgnoreCase(adoptionStatus) || completedElsewhere) {
             pet.setPetStatus(PET_STATUS_ADOPTED);
         } else {