diff --git a/.idea/.gitignore b/.idea/.gitignore
new file mode 100644
index 00000000..ab1f4164
--- /dev/null
+++ b/.idea/.gitignore
@@ -0,0 +1,10 @@
+# Default ignored files
+/shelf/
+/workspace.xml
+# Ignored default folder with query files
+/queries/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml
+# Editor-based HTTP Client requests
+/httpRequests/
diff --git a/.idea/group-2-threaded-project-petshop.iml b/.idea/group-2-threaded-project-petshop.iml
new file mode 100644
index 00000000..d6ebd480
--- /dev/null
+++ b/.idea/group-2-threaded-project-petshop.iml
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$" />
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/.idea/misc.xml b/.idea/misc.xml
new file mode 100644
index 00000000..4b151abf
--- /dev/null
+++ b/.idea/misc.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectRootManager" version="2">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/modules.xml b/.idea/modules.xml
new file mode 100644
index 00000000..e9d7459a
--- /dev/null
+++ b/.idea/modules.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/.idea/group-2-threaded-project-petshop.iml" filepath="$PROJECT_DIR$/.idea/group-2-threaded-project-petshop.iml" />
+    </modules>
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/vcs.xml b/.idea/vcs.xml
new file mode 100644
index 00000000..35eb1ddf
--- /dev/null
+++ b/.idea/vcs.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="" vcs="Git" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/android/.idea/gradle.xml b/android/.idea/gradle.xml
index cdbc250c..02c4aa5e 100644
--- a/android/.idea/gradle.xml
+++ b/android/.idea/gradle.xml
@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
+  <component name="GradleMigrationSettings" migrationVersion="1" />
   <component name="GradleSettings">
     <option name="linkedExternalProjectsSettings">
       <GradleProjectSettings>
diff --git a/android/.idea/misc.xml b/android/.idea/misc.xml
index 74dd639e..b2c751a3 100644
--- a/android/.idea/misc.xml
+++ b/android/.idea/misc.xml
@@ -1,4 +1,3 @@
-<?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ExternalStorageConfigurationManager" enabled="true" />
   <component name="ProjectRootManager" version="2" languageLevel="JDK_21" default="true" project-jdk-name="jbr-21" project-jdk-type="JavaSDK">
diff --git a/android/.idea/vcs.xml b/android/.idea/vcs.xml
new file mode 100644
index 00000000..6c0b8635
--- /dev/null
+++ b/android/.idea/vcs.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$/.." vcs="Git" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/android/app/src/main/java/com/example/petstoremobile/adapters/SaleAdapter.java b/android/app/src/main/java/com/example/petstoremobile/adapters/SaleAdapter.java
new file mode 100644
index 00000000..d5a73e42
--- /dev/null
+++ b/android/app/src/main/java/com/example/petstoremobile/adapters/SaleAdapter.java
@@ -0,0 +1,78 @@
+package com.example.petstoremobile.adapters;
+
+import android.graphics.Color;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.TextView;
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
+import com.example.petstoremobile.R;
+import com.example.petstoremobile.models.Sale;
+import java.util.List;
+
+public class SaleAdapter extends RecyclerView.Adapter<SaleAdapter.SaleViewHolder> {
+
+    private List<Sale> saleList;
+    private OnSaleClickListener saleClickListener;
+
+    public interface OnSaleClickListener {
+        void onSaleClick(int position);
+    }
+
+    public SaleAdapter(List<Sale> saleList, OnSaleClickListener saleClickListener) {
+        this.saleList = saleList;
+        this.saleClickListener = saleClickListener;
+    }
+
+    public static class SaleViewHolder extends RecyclerView.ViewHolder {
+        TextView tvSaleId, tvItemName, tvEmployeeName, tvSaleDate, tvTotal, tvPaymentMethod, tvRefundBadge;
+
+        public SaleViewHolder(@NonNull View v) {
+            super(v);
+            tvSaleId = v.findViewById(R.id.tvSaleId);
+            tvItemName = v.findViewById(R.id.tvSaleItemName);
+            tvEmployeeName = v.findViewById(R.id.tvSaleEmployee);
+            tvSaleDate = v.findViewById(R.id.tvSaleDate);
+            tvTotal = v.findViewById(R.id.tvSaleTotal);
+            tvPaymentMethod = v.findViewById(R.id.tvSalePayment);
+            tvRefundBadge = v.findViewById(R.id.tvRefundBadge);
+        }
+    }
+
+    @NonNull
+    @Override
+    public SaleViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_sale, parent, false);
+        return new SaleViewHolder(v);
+    }
+
+    @Override
+    public void onBindViewHolder(@NonNull SaleViewHolder holder, int position) {
+        Sale sale = saleList.get(position);
+
+        holder.tvSaleId.setText("ID: " + sale.getSaleId());
+        holder.tvItemName.setText(sale.getItemName());
+        holder.tvEmployeeName.setText("By: " + sale.getEmployeeName());
+        holder.tvSaleDate.setText(sale.getSaleDate());
+        holder.tvTotal.setText("$" + String.format("%.2f", sale.getTotal()));
+        holder.tvPaymentMethod.setText(sale.getPaymentMethod());
+
+        // Show refund badge if it's a refund
+        if (sale.isRefund()) {
+            holder.tvRefundBadge.setVisibility(View.VISIBLE);
+            holder.tvRefundBadge.setBackgroundColor(Color.parseColor("#F44336"));
+            holder.tvTotal.setTextColor(Color.parseColor("#F44336"));
+        } else {
+            holder.tvRefundBadge.setVisibility(View.GONE);
+            holder.tvTotal.setTextColor(Color.parseColor("#4CAF50"));
+        }
+
+        holder.itemView.setOnClickListener(v -> saleClickListener.onSaleClick(position));
+    }
+
+    @Override
+    public int getItemCount() {
+        return saleList.size();
+    }
+}
diff --git a/android/app/src/main/java/com/example/petstoremobile/api/SaleApi.java b/android/app/src/main/java/com/example/petstoremobile/api/SaleApi.java
new file mode 100644
index 00000000..55d1eef8
--- /dev/null
+++ b/android/app/src/main/java/com/example/petstoremobile/api/SaleApi.java
@@ -0,0 +1,33 @@
+package com.example.petstoremobile.api;
+
+import com.example.petstoremobile.dtos.PageResponse;
+import com.example.petstoremobile.dtos.SaleDTO;
+
+import retrofit2.Call;
+import retrofit2.http.Body;
+import retrofit2.http.DELETE;
+import retrofit2.http.GET;
+import retrofit2.http.POST;
+import retrofit2.http.PUT;
+import retrofit2.http.Path;
+import retrofit2.http.Query;
+
+public interface SaleApi {
+
+    @GET("api/v1/sales")
+    Call<PageResponse<SaleDTO>> getAllSales(
+            @Query("page") int page,
+            @Query("size") int size);
+
+    @GET("api/v1/sales/{id}")
+    Call<SaleDTO> getSaleById(@Path("id") Long id);
+
+    @POST("api/v1/sales")
+    Call<SaleDTO> createSale(@Body SaleDTO sale);
+
+    @PUT("api/v1/sales/{id}")
+    Call<SaleDTO> updateSale(@Path("id") Long id, @Body SaleDTO sale);
+
+    @DELETE("api/v1/sales/{id}")
+    Call<Void> deleteSale(@Path("id") Long id);
+}
\ No newline at end of file
diff --git a/android/app/src/main/java/com/example/petstoremobile/dtos/SaleDTO.java b/android/app/src/main/java/com/example/petstoremobile/dtos/SaleDTO.java
new file mode 100644
index 00000000..2cdb625f
--- /dev/null
+++ b/android/app/src/main/java/com/example/petstoremobile/dtos/SaleDTO.java
@@ -0,0 +1,82 @@
+package com.example.petstoremobile.dtos;
+
+public class SaleDTO {
+
+    private Long saleId;
+
+    private Long productId;
+    private String productName;
+
+    private Integer quantity;
+    private Double price;
+    private Double totalAmount;
+
+    private String saleDate;
+    private String customerName;
+
+    public SaleDTO() {}
+
+    public Long getSaleId() {
+        return saleId;
+    }
+
+    public void setSaleId(Long saleId) {
+        this.saleId = saleId;
+    }
+
+    public Long getProductId() {
+        return productId;
+    }
+
+    public void setProductId(Long productId) {
+        this.productId = productId;
+    }
+
+    public String getProductName() {
+        return productName;
+    }
+
+    public void setProductName(String productName) {
+        this.productName = productName;
+    }
+
+    public Integer getQuantity() {
+        return quantity;
+    }
+
+    public void setQuantity(Integer quantity) {
+        this.quantity = quantity;
+    }
+
+    public Double getPrice() {
+        return price;
+    }
+
+    public void setPrice(Double price) {
+        this.price = price;
+    }
+
+    public Double getTotalAmount() {
+        return totalAmount;
+    }
+
+    public void setTotalAmount(Double totalAmount) {
+        this.totalAmount = totalAmount;
+    }
+
+    public String getSaleDate() {
+        return saleDate;
+    }
+
+    public void setSaleDate(String saleDate) {
+        this.saleDate = saleDate;
+    }
+
+    public String getCustomerName() {
+        return customerName;
+    }
+
+    public void setCustomerName(String customerName) {
+        this.customerName = customerName;
+    }
+}
\ No newline at end of file
diff --git a/android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/SaleFragment.java b/android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/SaleFragment.java
new file mode 100644
index 00000000..544cd378
--- /dev/null
+++ b/android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/SaleFragment.java
@@ -0,0 +1,130 @@
+package com.example.petstoremobile.fragments.listfragments;
+
+import android.os.Bundle;
+import androidx.fragment.app.Fragment;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
+import android.text.Editable;
+import android.text.TextWatcher;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.EditText;
+import com.example.petstoremobile.R;
+import com.example.petstoremobile.adapters.SaleAdapter;
+import com.example.petstoremobile.fragments.ListFragment;
+import com.example.petstoremobile.fragments.listfragments.detailfragments.RefundDetailFragment;
+import com.example.petstoremobile.models.Sale;
+import java.util.ArrayList;
+import java.util.List;
+
+public class SaleFragment extends Fragment implements SaleAdapter.OnSaleClickListener {
+
+    private List<Sale> saleList = new ArrayList<>();
+    private List<Sale> filteredList = new ArrayList<>();
+    private SaleAdapter adapter;
+    private SwipeRefreshLayout swipeRefreshLayout;
+    private EditText etSearch;
+
+    @Override
+    public View onCreateView(LayoutInflater inflater, ViewGroup container,
+                             Bundle savedInstanceState) {
+        View view = inflater.inflate(R.layout.fragment_sale, container, false);
+
+        setupRecyclerView(view);
+        loadSaleData(); 
+        setupSearch(view);
+        setupSwipeRefresh(view);
+
+        return view;
+    }
+
+    private void setupSearch(View view) {
+        etSearch = view.findViewById(R.id.etSearchSale);
+        etSearch.addTextChangedListener(new TextWatcher() {
+            @Override
+            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
+            }
+
+            @Override
+            public void onTextChanged(CharSequence s, int start, int before, int count) {
+                filterSales(s.toString());
+            }
+
+            @Override
+            public void afterTextChanged(Editable s) {
+            }
+        });
+    }
+
+    private void filterSales(String query) {
+        filteredList.clear();
+        if (query.isEmpty()) {
+            filteredList.addAll(saleList);
+        } else {
+            String lower = query.toLowerCase();
+            for (Sale s : saleList) {
+                if (s.getItemName().toLowerCase().contains(lower)
+                        || s.getEmployeeName().toLowerCase().contains(lower)
+                        || s.getSaleDate().toLowerCase().contains(lower)
+                        || s.getPaymentMethod().toLowerCase().contains(lower)
+                        || String.valueOf(s.getSaleId()).contains(lower)) {
+                    filteredList.add(s);
+                }
+            }
+        }
+        adapter.notifyDataSetChanged();
+    }
+
+    private void setupSwipeRefresh(View view) {
+        swipeRefreshLayout = view.findViewById(R.id.swipeRefreshSale);
+        swipeRefreshLayout.setOnRefreshListener(() -> {
+            loadSaleData();
+            swipeRefreshLayout.setRefreshing(false);
+        });
+    }
+
+    // When a sale row is clicked, open the refund screen for that sale
+    @Override
+    public void onSaleClick(int position) {
+        Sale sale = filteredList.get(position);
+        RefundDetailFragment refundFragment = new RefundDetailFragment();
+        Bundle args = new Bundle();
+        args.putInt("saleId", sale.getSaleId());
+        args.putString("saleDate", sale.getSaleDate());
+        args.putString("employeeName", sale.getEmployeeName());
+        args.putDouble("total", sale.getTotal());
+        args.putString("paymentMethod", sale.getPaymentMethod());
+        refundFragment.setArguments(args);
+        refundFragment.setSaleFragment(this);
+
+        ListFragment listFragment = (ListFragment) getParentFragment();
+        if (listFragment != null)
+            listFragment.loadFragment(refundFragment);
+    }
+
+    public void reloadSales() {
+        loadSaleData();
+    }
+
+    // TODO: Replace with actual API call - GET v1/sales
+    private void loadSaleData() {
+        saleList.clear();
+        saleList.add(new Sale(1, "2026-03-01", "John Smith", "Premium Dog Food", 2, 45.99, 91.98, "Card", false));
+        saleList.add(new Sale(2, "2026-03-02", "Jane Doe", "Cat Toy Bundle", 1, 19.99, 19.99, "Cash", false));
+        saleList.add(new Sale(3, "2026-03-03", "John Smith", "Pet Shampoo", 3, 12.99, 38.97, "Card", false));
+        saleList.add(new Sale(4, "2026-03-04", "Jane Doe", "Dog Bed - Large", 1, 89.99, 89.99, "Cash", true));
+        filteredList.clear();
+        filteredList.addAll(saleList);
+        if (adapter != null)
+            adapter.notifyDataSetChanged();
+    }
+
+    private void setupRecyclerView(View view) {
+        RecyclerView recyclerView = view.findViewById(R.id.recyclerViewSales);
+        adapter = new SaleAdapter(filteredList, this);
+        recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
+        recyclerView.setAdapter(adapter);
+    }
+}
diff --git a/android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/PurchaseOrderDetailFragment.java b/android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/PurchaseOrderDetailFragment.java
new file mode 100644
index 00000000..47dae4d8
--- /dev/null
+++ b/android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/PurchaseOrderDetailFragment.java
@@ -0,0 +1,55 @@
+package com.example.petstoremobile.fragments.listfragments.detailfragments;
+
+import android.graphics.Color;
+import android.os.Bundle;
+import android.view.*;
+import android.widget.*;
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import com.example.petstoremobile.R;
+import com.example.petstoremobile.fragments.ListFragment;
+
+public class PurchaseOrderDetailFragment extends Fragment {
+
+    private TextView tvId, tvSupplier, tvDate, tvStatus;
+    private Button btnBack;
+
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
+                             Bundle savedInstanceState) {
+        View view = inflater.inflate(R.layout.fragment_purchase_order_detail, container, false);
+
+        tvId       = view.findViewById(R.id.tvPODetailId);
+        tvSupplier = view.findViewById(R.id.tvPODetailSupplier);
+        tvDate     = view.findViewById(R.id.tvPODetailDate);
+        tvStatus   = view.findViewById(R.id.tvPODetailStatus);
+        btnBack    = view.findViewById(R.id.btnPOBack);
+
+        Bundle a = getArguments();
+        if (a != null) {
+            tvId.setText("PO #" + a.getLong("purchaseOrderId"));
+            tvSupplier.setText(a.getString("supplierName"));
+            tvDate.setText(a.getString("orderDate"));
+
+            String status = a.getString("status", "");
+            tvStatus.setText(status);
+            switch (status) {
+                case "Completed":
+                    tvStatus.setTextColor(Color.parseColor("#4CAF50")); break;
+                case "Pending":
+                    tvStatus.setTextColor(Color.parseColor("#FF9800")); break;
+                case "Cancelled":
+                    tvStatus.setTextColor(Color.parseColor("#F44336")); break;
+                default:
+                    tvStatus.setTextColor(Color.parseColor("#9E9E9E")); break;
+            }
+        }
+
+        btnBack.setOnClickListener(v -> {
+            ListFragment lf = (ListFragment) getParentFragment();
+            if (lf != null) lf.getChildFragmentManager().popBackStack();
+        });
+
+        return view;
+    }
+}
diff --git a/android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/RefundDetailFragment.java b/android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/RefundDetailFragment.java
new file mode 100644
index 00000000..55c0561e
--- /dev/null
+++ b/android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/RefundDetailFragment.java
@@ -0,0 +1,135 @@
+package com.example.petstoremobile.fragments.listfragments.detailfragments;
+
+import android.os.Bundle;
+import androidx.fragment.app.Fragment;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ArrayAdapter;
+import android.widget.Button;
+import android.widget.EditText;
+import android.widget.Spinner;
+import android.widget.TextView;
+import android.widget.Toast;
+import com.example.petstoremobile.R;
+import com.example.petstoremobile.fragments.ListFragment;
+import com.example.petstoremobile.fragments.listfragments.SaleFragment;
+import com.example.petstoremobile.utils.ActivityLogger;
+import com.example.petstoremobile.utils.InputValidator;
+
+public class RefundDetailFragment extends Fragment {
+
+    private EditText etRefundSaleId, etRefundReason;
+    private TextView tvSaleInfo;
+    private Spinner spinnerRefundPayment;
+    private Button btnLoadSale, btnProcessRefund, btnBack;
+    private int saleId;
+    private SaleFragment saleFragment;
+
+    public void setSaleFragment(SaleFragment fragment) {
+        this.saleFragment = fragment;
+    }
+
+    @Override
+    public View onCreateView(LayoutInflater inflater, ViewGroup container,
+                             Bundle savedInstanceState) {
+        View view = inflater.inflate(R.layout.fragment_refund_detail, container, false);
+
+        initViews(view);
+        setupSpinner();
+        handleArguments();
+
+        btnBack.setOnClickListener(v -> goBack());
+        btnLoadSale.setOnClickListener(v -> loadSaleDetails());
+        btnProcessRefund.setOnClickListener(v -> processRefund());
+
+        return view;
+    }
+
+    private void loadSaleDetails() {
+        String idText = etRefundSaleId.getText().toString().trim();
+        if (idText.isEmpty()) {
+            Toast.makeText(getContext(), "Enter a Sale ID", Toast.LENGTH_SHORT).show();
+            return;
+        }
+
+        try {
+            int id = Integer.parseInt(idText);
+            // TODO: Replace with actual API call - GET v1/sales/{id}
+            // For now show placeholder info
+            tvSaleInfo.setText("Sale ID: " + id + " loaded. Enter reason and payment method to process refund.");
+            tvSaleInfo.setTextColor(getResources().getColor(android.R.color.holo_green_dark));
+        } catch (NumberFormatException e) {
+            Toast.makeText(getContext(), "Invalid Sale ID", Toast.LENGTH_SHORT).show();
+        }
+    }
+
+    private void processRefund() {
+        if (!InputValidator.isNotEmpty(etRefundSaleId, "Sale ID"))
+            return;
+        if (!InputValidator.isNotEmpty(etRefundReason, "Refund Reason"))
+            return;
+
+        String idText = etRefundSaleId.getText().toString().trim();
+        String reason = etRefundReason.getText().toString().trim();
+        String payment = spinnerRefundPayment.getSelectedItem().toString();
+
+        try {
+            int id = Integer.parseInt(idText);
+            // TODO: Replace with actual API call - POST v1/refunds
+            ActivityLogger.log(requireContext(), "Processed refund for Sale ID: " + id + " - Reason: " + reason);
+            Toast.makeText(getContext(), "Refund processed for Sale ID: " + id, Toast.LENGTH_SHORT).show();
+            if (saleFragment != null)
+                saleFragment.reloadSales();
+            goBack();
+        } catch (NumberFormatException e) {
+            Toast.makeText(getContext(), "Invalid Sale ID", Toast.LENGTH_SHORT).show();
+        }
+    }
+
+    private void handleArguments() {
+        if (getArguments() != null && getArguments().containsKey("saleId")) {
+            saleId = getArguments().getInt("saleId");
+            etRefundSaleId.setText(String.valueOf(saleId));
+            String info = "Sale Date: " + getArguments().getString("saleDate")
+                    + " | Employee: " + getArguments().getString("employeeName")
+                    + " | Total: $" + String.format("%.2f", getArguments().getDouble("total"))
+                    + " | Payment: " + getArguments().getString("paymentMethod");
+            tvSaleInfo.setText(info);
+            tvSaleInfo.setTextColor(getResources().getColor(android.R.color.holo_green_dark));
+
+            // Pre-select payment method
+            String payment = getArguments().getString("paymentMethod");
+            ArrayAdapter<String> adapter = (ArrayAdapter<String>) spinnerRefundPayment.getAdapter();
+            if (adapter != null && payment != null) {
+                int pos = adapter.getPosition(payment);
+                if (pos >= 0)
+                    spinnerRefundPayment.setSelection(pos);
+            }
+        }
+    }
+
+    private void goBack() {
+        ListFragment listFragment = (ListFragment) getParentFragment();
+        if (listFragment != null)
+            listFragment.getChildFragmentManager().popBackStack();
+    }
+
+    private void initViews(View view) {
+        etRefundSaleId = view.findViewById(R.id.etRefundSaleId);
+        etRefundReason = view.findViewById(R.id.etRefundReason);
+        tvSaleInfo = view.findViewById(R.id.tvSaleInfo);
+        spinnerRefundPayment = view.findViewById(R.id.spinnerRefundPayment);
+        btnLoadSale = view.findViewById(R.id.btnLoadSale);
+        btnProcessRefund = view.findViewById(R.id.btnProcessRefund);
+        btnBack = view.findViewById(R.id.btnRefundBack);
+    }
+
+    private void setupSpinner() {
+        ArrayAdapter<String> adapter = new ArrayAdapter<>(requireContext(),
+                android.R.layout.simple_spinner_item,
+                new String[] { "Cash", "Card", "Debit" });
+        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
+        spinnerRefundPayment.setAdapter(adapter);
+    }
+}
diff --git a/android/app/src/main/java/com/example/petstoremobile/models/Sale.java b/android/app/src/main/java/com/example/petstoremobile/models/Sale.java
new file mode 100644
index 00000000..ce305d58
--- /dev/null
+++ b/android/app/src/main/java/com/example/petstoremobile/models/Sale.java
@@ -0,0 +1,62 @@
+package com.example.petstoremobile.models;
+
+public class Sale {
+    private int saleId;
+    private String saleDate;
+    private String employeeName;
+    private String itemName;
+    private int quantity;
+    private double unitPrice;
+    private double total;
+    private String paymentMethod;
+    private boolean isRefund;
+
+    public Sale(int saleId, String saleDate, String employeeName, String itemName,
+                int quantity, double unitPrice, double total, String paymentMethod, boolean isRefund) {
+        this.saleId = saleId;
+        this.saleDate = saleDate;
+        this.employeeName = employeeName;
+        this.itemName = itemName;
+        this.quantity = quantity;
+        this.unitPrice = unitPrice;
+        this.total = total;
+        this.paymentMethod = paymentMethod;
+        this.isRefund = isRefund;
+    }
+
+    public int getSaleId() {
+        return saleId;
+    }
+
+    public String getSaleDate() {
+        return saleDate;
+    }
+
+    public String getEmployeeName() {
+        return employeeName;
+    }
+
+    public String getItemName() {
+        return itemName;
+    }
+
+    public int getQuantity() {
+        return quantity;
+    }
+
+    public double getUnitPrice() {
+        return unitPrice;
+    }
+
+    public double getTotal() {
+        return total;
+    }
+
+    public String getPaymentMethod() {
+        return paymentMethod;
+    }
+
+    public boolean isRefund() {
+        return isRefund;
+    }
+}
diff --git a/android/app/src/main/res/layout/fragment_refund_detail.xml b/android/app/src/main/res/layout/fragment_refund_detail.xml
new file mode 100644
index 00000000..1f88c910
--- /dev/null
+++ b/android/app/src/main/res/layout/fragment_refund_detail.xml
@@ -0,0 +1,154 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical"
+    android:background="@color/background_grey">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="56dp"
+        android:background="@color/primary_dark"
+        android:gravity="center_vertical"
+        android:paddingStart="16dp"
+        android:paddingEnd="16dp"
+        android:orientation="horizontal">
+
+        <TextView
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="Process Refund"
+            android:textColor="@color/white"
+            android:textSize="20sp"
+            android:textStyle="bold"/>
+
+    </LinearLayout>
+
+    <ScrollView
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            android:padding="24dp">
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:orientation="vertical"
+                android:background="@drawable/rounded_card"
+                android:padding="16dp"
+                android:layout_marginBottom="16dp">
+
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Sale ID"
+                    android:textColor="@color/text_dark"
+                    android:textSize="12sp"
+                    android:layout_marginBottom="4dp"/>
+
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:orientation="horizontal">
+
+                    <EditText
+                        android:id="@+id/etRefundSaleId"
+                        android:layout_width="0dp"
+                        android:layout_height="wrap_content"
+                        android:layout_weight="1"
+                        android:hint="Enter Sale ID"
+                        android:inputType="number"
+                        android:layout_marginEnd="8dp"
+                        android:layout_marginBottom="16dp"/>
+
+                    <Button
+                        android:id="@+id/btnLoadSale"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="Load"
+                        android:backgroundTint="@color/primary_medium"
+                        android:textColor="@color/white"/>
+
+                </LinearLayout>
+
+                <TextView
+                    android:id="@+id/tvSaleInfo"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:text="Load a sale to see details"
+                    android:textColor="#888888"
+                    android:textSize="13sp"
+                    android:layout_marginBottom="16dp"/>
+
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Refund Reason"
+                    android:textColor="@color/text_dark"
+                    android:textSize="12sp"
+                    android:layout_marginBottom="4dp"/>
+
+                <EditText
+                    android:id="@+id/etRefundReason"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:hint="Enter reason for refund"
+                    android:inputType="textMultiLine"
+                    android:lines="3"
+                    android:layout_marginBottom="16dp"/>
+
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Payment Method"
+                    android:textColor="@color/text_dark"
+                    android:textSize="12sp"
+                    android:layout_marginBottom="4dp"/>
+
+                <Spinner
+                    android:id="@+id/spinnerRefundPayment"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"/>
+
+            </LinearLayout>
+
+        </LinearLayout>
+
+    </ScrollView>
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="horizontal"
+        android:background="@color/white"
+        android:padding="16dp">
+
+        <Button
+            android:id="@+id/btnRefundBack"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:layout_marginEnd="8dp"
+            android:text="Back"
+            android:backgroundTint="@color/primary_medium"
+            android:textColor="@color/white"/>
+
+        <Button
+            android:id="@+id/btnProcessRefund"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:layout_marginStart="8dp"
+            android:text="Process Refund"
+            android:backgroundTint="@color/accent_coral"
+            android:textColor="@color/white"/>
+
+    </LinearLayout>
+
+</LinearLayout>
diff --git a/android/app/src/main/res/layout/fragment_sale.xml b/android/app/src/main/res/layout/fragment_sale.xml
new file mode 100644
index 00000000..14f81258
--- /dev/null
+++ b/android/app/src/main/res/layout/fragment_sale.xml
@@ -0,0 +1,40 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.coordinatorlayout.widget.CoordinatorLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="@color/background_grey">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:orientation="vertical">
+
+        <EditText
+            android:id="@+id/etSearchSale"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_margin="8dp"
+            android:hint="Search by item, employee or date..."
+            android:inputType="text"
+            android:drawableStart="@android:drawable/ic_menu_search"
+            android:drawablePadding="8dp"
+            android:background="@android:color/white"
+            android:padding="12dp"/>
+
+        <androidx.swiperefreshlayout.widget.SwipeRefreshLayout
+            android:id="@+id/swipeRefreshSale"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent">
+
+            <androidx.recyclerview.widget.RecyclerView
+                android:id="@+id/recyclerViewSales"
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                android:padding="8dp"/>
+
+        </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
+
+    </LinearLayout>
+
+</androidx.coordinatorlayout.widget.CoordinatorLayout>
diff --git a/android/app/src/main/res/layout/item_sale.xml b/android/app/src/main/res/layout/item_sale.xml
new file mode 100644
index 00000000..296fdded
--- /dev/null
+++ b/android/app/src/main/res/layout/item_sale.xml
@@ -0,0 +1,104 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:orientation="vertical"
+    android:paddingStart="16dp"
+    android:paddingEnd="16dp"
+    android:paddingTop="16dp"
+    android:paddingBottom="16dp"
+    android:background="@color/white">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="horizontal"
+        android:gravity="center_vertical">
+
+        <TextView
+            android:id="@+id/tvSaleItemName"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:textColor="@color/text_dark"
+            android:textSize="18sp"
+            android:textStyle="bold"
+            android:ellipsize="end"
+            android:maxLines="1"
+            android:text="Item Name"/>
+
+        <TextView
+            android:id="@+id/tvRefundBadge"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:paddingStart="8dp"
+            android:paddingEnd="8dp"
+            android:paddingTop="3dp"
+            android:paddingBottom="3dp"
+            android:text="REFUND"
+            android:textColor="@color/white"
+            android:textSize="11sp"
+            android:visibility="gone"/>
+
+    </LinearLayout>
+
+    <TextView
+        android:id="@+id/tvSaleEmployee"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="4dp"
+        android:textColor="#888888"
+        android:textSize="13sp"
+        android:text="By: Employee"/>
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="horizontal"
+        android:layout_marginTop="8dp"
+        android:gravity="center_vertical">
+
+        <TextView
+            android:id="@+id/tvSaleId"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:textColor="#888888"
+            android:textSize="12sp"
+            android:text="ID: 0"/>
+
+        <TextView
+            android:id="@+id/tvSaleDate"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:textColor="#888888"
+            android:textSize="12sp"
+            android:text="Date"/>
+
+        <TextView
+            android:id="@+id/tvSalePayment"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:textColor="#888888"
+            android:textSize="12sp"
+            android:layout_marginEnd="8dp"
+            android:text="Cash"/>
+
+        <TextView
+            android:id="@+id/tvSaleTotal"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:textSize="16sp"
+            android:textStyle="bold"
+            android:text="$0.00"/>
+
+    </LinearLayout>
+
+    <View
+        android:layout_width="match_parent"
+        android:layout_height="1dp"
+        android:background="#F0F0F0"
+        android:layout_marginTop="12dp"/>
+
+</LinearLayout>
diff --git a/backend/petshop-api.postman_collection.json b/backend/petshop-api.postman_collection.json
index d95a5b86..e8be58ef 100644
--- a/backend/petshop-api.postman_collection.json
+++ b/backend/petshop-api.postman_collection.json
@@ -1,6 +1,6 @@
 {
   "info": {
-    "name": "PetShop API Complete Collection",
+    "name": "PetShop  Complete Collection",
     "_postman_id": "petshop-api-complete-v1",
     "description": "Complete API collection with all 95+ verified endpoints",
     "schema": "https://schema.getpostman.com/json/collection/v2.1.0/collection.json"