diff --git a/services/nginx/app/classes/department_wash_count_service.php b/services/nginx/app/classes/department_wash_count_service.php
index 8bb55a55..77a74520 100644
--- a/services/nginx/app/classes/department_wash_count_service.php
+++ b/services/nginx/app/classes/department_wash_count_service.php
@@ -2,6 +2,8 @@
 
 namespace classes;
 
+require_once WD . '/classes/selfserve_schema_bootstrap.php';
+
 use Exception;
 
 class department_wash_count_service
diff --git a/services/nginx/app/classes/selfserve_schema_bootstrap.php b/services/nginx/app/classes/selfserve_schema_bootstrap.php
index 50ad00a4..23545c67 100644
--- a/services/nginx/app/classes/selfserve_schema_bootstrap.php
+++ b/services/nginx/app/classes/selfserve_schema_bootstrap.php
@@ -73,7 +73,9 @@ class selfserve_schema_bootstrap
                 INDEX idx_selfserve_wash_sessions_lane_reg (lane_id, reg),
                 INDEX idx_selfserve_wash_sessions_status (status),
                 INDEX idx_selfserve_wash_sessions_customer (customer_number),
-                INDEX idx_selfserve_wash_sessions_created_at (created_at)
+                INDEX idx_selfserve_wash_sessions_created_at (created_at),
+                INDEX idx_selfserve_wash_sessions_department_completed (department_id, completed_at),
+                INDEX idx_selfserve_wash_sessions_order (order_id)
             ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci",
 
             "CREATE TABLE IF NOT EXISTS selfserve_wash_session_answers (
@@ -219,6 +221,16 @@ class selfserve_schema_bootstrap
             'wash_started_at',
             'ALTER TABLE selfserve_wash_sessions ADD COLUMN wash_started_at DATETIME NULL AFTER machine_start_triggered_at'
         );
+        self::ensureIndex(
+            'selfserve_wash_sessions',
+            'idx_selfserve_wash_sessions_department_completed',
+            'ALTER TABLE selfserve_wash_sessions ADD INDEX idx_selfserve_wash_sessions_department_completed (department_id, completed_at)'
+        );
+        self::ensureIndex(
+            'selfserve_wash_sessions',
+            'idx_selfserve_wash_sessions_order',
+            'ALTER TABLE selfserve_wash_sessions ADD INDEX idx_selfserve_wash_sessions_order (order_id)'
+        );
 
         self::$initialized = true;
     }
@@ -252,6 +264,35 @@ class selfserve_schema_bootstrap
         $db->query($alterSql);
     }
 
+    public static function tableHasIndex(string $table, string $index): bool
+    {
+        global $db;
+        $table = $db->escape_string($table);
+        $index = $db->escape_string($index);
+        $database = $db->escape_string($db->getDatabase());
+
+        $sql = "SELECT COUNT(*) AS c
+                FROM information_schema.STATISTICS
+                WHERE TABLE_SCHEMA = '$database'
+                  AND TABLE_NAME = '$table'
+                  AND INDEX_NAME = '$index'";
+        $result = $db->query($sql);
+        if (!$result) {
+            return false;
+        }
+        $row = $result->fetch_assoc();
+        return ((int)($row['c'] ?? 0)) > 0;
+    }
+
+    public static function ensureIndex(string $table, string $index, string $alterSql): void
+    {
+        global $db;
+        if (self::tableHasIndex($table, $index)) {
+            return;
+        }
+        $db->query($alterSql);
+    }
+
     /**
      * @param array<int,string> $acceptedDataTypes
      */
diff --git a/services/nginx/app/modules/selfserve/classes/selfserve_wash_flow.php b/services/nginx/app/modules/selfserve/classes/selfserve_wash_flow.php
index 17b8de0a..9cce84ad 100644
--- a/services/nginx/app/modules/selfserve/classes/selfserve_wash_flow.php
+++ b/services/nginx/app/modules/selfserve/classes/selfserve_wash_flow.php
@@ -440,6 +440,8 @@ class selfserve_wash_flow implements selfserve_wash_flow_i
             return null;
         }
 
+        $this->fillMissingWashStartedAtFromLaneRuntime($session, $laneId);
+
         if (!$session->markCompletedIfOpen($orderId)) {
             return $this->getSessionSummary((int)$session->id);
         }
@@ -456,6 +458,25 @@ class selfserve_wash_flow implements selfserve_wash_flow_i
         return $this->getSessionSummary((int)$session->id);
     }
 
+    protected function fillMissingWashStartedAtFromLaneRuntime(selfserve_wash_sessions_o $session, int $laneId): void
+    {
+        try {
+            if ($session->wash_started_at->value() !== null) {
+                return;
+            }
+
+            $lane = (new selfserve())->lane($laneId);
+            $washStartedAt = (int)$lane->getWashStartTime();
+            if ($washStartedAt <= 0) {
+                return;
+            }
+
+            $session->wash_started_at->set(date('Y-m-d H:i:s', $washStartedAt));
+        } catch (\Throwable) {
+            // Session timestamp enrichment must not block STOP completion.
+        }
+    }
+
     public function forceStopLane(int $laneId, ?int $sessionId = null, bool $bill = false, ?string $reason = null, ?int $userId = null): array
     {
         $lane = (new selfserve())->lane($laneId);
diff --git a/services/nginx/app/objects/department_daily_reports_o.php b/services/nginx/app/objects/department_daily_reports_o.php
index 0bc54af1..e98e9d16 100644
--- a/services/nginx/app/objects/department_daily_reports_o.php
+++ b/services/nginx/app/objects/department_daily_reports_o.php
@@ -2,7 +2,10 @@
 
 namespace objects;
 
+require_once WD . '/classes/department_wash_count_service.php';
+
 use classes\db;
+use classes\department_wash_count_service;
 use classes\object_property;
 use Exception;
 use traits\db_object_t;
@@ -510,8 +513,6 @@ class department_daily_reports_o extends db
     public function getTransactionsOnDateWashesCount(string $date, int $department_id, string $date_to = null): int
     {
         return self::methodCacheWithParameters(__METHOD__, func_get_args(), 120, function() use ($date, $department_id, $date_to) {
-            global /** @var db $db */
-            $db;
             // If the date_to is null, set it to the date
             if ($date_to === null) {
                 $date_to = $date; // Making the report for an entire day
@@ -519,33 +520,7 @@ class department_daily_reports_o extends db
             // Set the date time to cover the entire day
             $date = date('Y-m-d 00:00:00', strtotime($date));
             $date_to = date('Y-m-d 23:59:59', strtotime($date_to));
-            $conn = $db->conn();
-            // Get all the product prices, in all the orders (Not counting removed orders), for the given date and department, and sum them
-            $stmt = $conn->prepare(
-                'SELECT COUNT(DISTINCT o.id) as amount FROM orders o
-                        JOIN order_items oi ON o.id = oi.order_id
-                        JOIN products p ON oi.product_id = p.id
-                        WHERE o.department_id = ? AND DATE(o.created_at) BETWEEN ? AND ? AND o.deleted_at IS NULL AND oi.deleted_at IS NULL AND p.is_wash = 1'
-            );
-            if ($stmt) {
-                $stmt->bind_param('iss', $department_id, $date, $date_to); // Bind parameters (i = integer, s = string)
-                $stmt->execute();
-                $result = $stmt->get_result(); // Get the result set from the statement
-                $data = $result->fetch_assoc(); // Fetch the result as an associative array
-
-                // Access the "amount" field
-                if (!$data) {
-                    // If there are no orders, set the amount to 0
-                    $amount = 0;
-                } else {
-                    $amount = $data['amount'];
-                }
-                $stmt->close(); // Close the statement
-            } else {
-                // Handle query preparation error
-                die('Query preparation failed: ' . $conn->error);
-            }
-            return (int)$amount;
+            return (new department_wash_count_service())->countInDateRange($date, $date_to, $department_id);
         });
     }
 
@@ -616,9 +591,6 @@ class department_daily_reports_o extends db
      */
     public function getTransactionSummaryForDepartments(string $date, array $department_ids, string $date_to = null): array
     {
-        global /** @var db $db */
-        $db;
-
         $normalized_department_ids = $this->normalizeDepartmentIds($department_ids);
         if ($normalized_department_ids === []) {
             return [
@@ -631,30 +603,17 @@ class department_daily_reports_o extends db
         }
 
         [$date_start, $date_end] = $this->resolveDateRange($date, $date_to);
-        $department_ids_sql = implode(',', $normalized_department_ids);
-        $escaped_start = $db->escape_string($date_start);
-        $escaped_end = $db->escape_string($date_end);
-
-        $sql = "SELECT COUNT(DISTINCT o.id) AS quantity,
-                       COALESCE(SUM(oi.quantity), 0) AS products,
-                       COALESCE(SUM(oi.price * oi.quantity), 0) AS earnings,
-                       COUNT(DISTINCT CASE WHEN p.is_wash = 1 THEN o.id END) AS washes
-                FROM orders o
-                JOIN order_items oi ON oi.order_id = o.id
-                LEFT JOIN products p ON p.id = oi.product_id
-                WHERE o.department_id IN ($department_ids_sql)
-                  AND o.created_at BETWEEN '$escaped_start' AND '$escaped_end'
-                  AND o.deleted_at IS NULL
-                  AND oi.deleted_at IS NULL";
-
-        $result = $db->query($sql);
-        $row = is_object($result) ? $result->fetch_assoc() : null;
+        $transaction_summary = (new department_wash_count_service())->transactionSummary(
+            $date_start,
+            $date_end,
+            $normalized_department_ids
+        );
 
         return [
-            'quantity' => (int)($row['quantity'] ?? 0),
-            'products' => (int)($row['products'] ?? 0),
-            'earnings' => (int)round((float)($row['earnings'] ?? 0)),
-            'washes' => (int)($row['washes'] ?? 0),
+            'quantity' => (int)($transaction_summary['quantity'] ?? 0),
+            'products' => (int)($transaction_summary['products'] ?? 0),
+            'earnings' => (int)($transaction_summary['earnings'] ?? 0),
+            'washes' => (int)($transaction_summary['washes'] ?? 0),
             'water_usage' => $this->getWaterUsageForDepartments($date, $normalized_department_ids, $date_to),
         ];
     }
@@ -758,45 +717,13 @@ class department_daily_reports_o extends db
      */
     public function getWashTransactionsForDepartments(string $date, array $department_ids, string $date_to = null): array
     {
-        global /** @var db $db */
-        $db;
-
         $normalized_department_ids = $this->normalizeDepartmentIds($department_ids);
         if ($normalized_department_ids === []) {
             return [];
         }
 
         [$date_start, $date_end] = $this->resolveDateRange($date, $date_to);
-        $department_ids_sql = implode(',', $normalized_department_ids);
-        $escaped_start = $db->escape_string($date_start);
-        $escaped_end = $db->escape_string($date_end);
-
-        $sql = "SELECT DISTINCT o.id, o.department_id, o.created_at
-                FROM orders o
-                JOIN order_items oi ON oi.order_id = o.id
-                JOIN products p ON p.id = oi.product_id
-                WHERE o.department_id IN ($department_ids_sql)
-                  AND o.created_at BETWEEN '$escaped_start' AND '$escaped_end'
-                  AND o.deleted_at IS NULL
-                  AND oi.deleted_at IS NULL
-                  AND p.is_wash = 1
-                ORDER BY o.created_at ASC";
-
-        $result = $db->query($sql);
-        if (!is_object($result) || $result->num_rows === 0) {
-            return [];
-        }
-
-        $rows = [];
-        while ($row = $result->fetch_assoc()) {
-            $rows[] = [
-                'id' => (int)($row['id'] ?? 0),
-                'department_id' => (int)($row['department_id'] ?? 0),
-                'created_at' => (string)($row['created_at'] ?? ''),
-            ];
-        }
-
-        return $rows;
+        return (new department_wash_count_service())->listTransactions($date_start, $date_end, $normalized_department_ids);
     }
 
     /**
diff --git a/services/nginx/app/objects/orders_o.php b/services/nginx/app/objects/orders_o.php
index 5a28ab8c..9efb4809 100644
--- a/services/nginx/app/objects/orders_o.php
+++ b/services/nginx/app/objects/orders_o.php
@@ -2,8 +2,11 @@
 
 namespace objects;
 
+require_once WD . '/classes/department_wash_count_service.php';
+
 use attachments\helpers\attachment_content;
 use classes\db;
+use classes\department_wash_count_service;
 use classes\email;
 use classes\invoicing_period_utils;
 use classes\orders_schema_bootstrap;
@@ -2005,33 +2008,7 @@ class orders_o extends db
 
     public function countWashesInDateRange(string $date_start, string $date_end, int $department_id): int
     {
-        global /** @var db $db */
-        $db;
-        // Validate the date range
-        if (strtotime($date_start) === false || strtotime($date_end) === false) {
-            throw new Exception('Invalid date range provided');
-        }
-        if (strtotime($date_start) > strtotime($date_end)) {
-            throw new Exception('The start date cannot be after the end date');
-        }
-        // Prepare the SQL query to count washes in the date range for the department
-        $date_start = $db->escape_string($date_start);
-        $date_end = $db->escape_string($date_end);
-        // Get the amount of orders with at least one order item that has a product with the is_wash column set to true
-        $sql = "SELECT COUNT(DISTINCT o.id) AS wash_count
-                FROM $this->table o
-                JOIN order_items oi ON oi.order_id = o.id
-                JOIN products p ON p.id = oi.product_id
-                WHERE o.department_id = $department_id
-                  AND o.created_at BETWEEN '$date_start' AND '$date_end'
-                  AND o.deleted_at IS NULL
-                  AND p.is_wash = 1";
-        $result = $db->query($sql);
-        if ($result->num_rows === 0) {
-            return 0; // No washes found in the date range
-        }
-        $row = $result->fetch_assoc();
-        return (int)$row['wash_count'];
+        return (new department_wash_count_service())->countInDateRange($date_start, $date_end, $department_id);
     }
 
     /**
@@ -2041,58 +2018,7 @@ class orders_o extends db
      */
     public function countWashesByHourForDepartments(string $date_start, string $date_end, array $department_ids): array
     {
-        global /** @var db $db */
-        $db;
-
-        if (strtotime($date_start) === false || strtotime($date_end) === false) {
-            throw new Exception('Invalid date range provided');
-        }
-        if (strtotime($date_start) > strtotime($date_end)) {
-            throw new Exception('The start date cannot be after the end date');
-        }
-
-        $normalized_department_ids = [];
-        foreach ($department_ids as $department_id) {
-            $normalized_id = (int)$department_id;
-            if ($normalized_id > 0) {
-                $normalized_department_ids[$normalized_id] = true;
-            }
-        }
-        if ($normalized_department_ids === []) {
-            return [];
-        }
-
-        $department_ids_sql = implode(',', array_map('intval', array_keys($normalized_department_ids)));
-        $escaped_start = $db->escape_string($date_start);
-        $escaped_end = $db->escape_string($date_end);
-
-        $sql = "SELECT o.department_id,
-                       DATE_FORMAT(o.created_at, '%Y-%m-%d %H:00:00') AS hour_bucket,
-                       COUNT(DISTINCT o.id) AS wash_count
-                FROM $this->table o
-                JOIN order_items oi ON oi.order_id = o.id
-                JOIN products p ON p.id = oi.product_id
-                WHERE o.department_id IN ($department_ids_sql)
-                  AND o.created_at BETWEEN '$escaped_start' AND '$escaped_end'
-                  AND o.deleted_at IS NULL
-                  AND p.is_wash = 1
-                GROUP BY o.department_id, DATE_FORMAT(o.created_at, '%Y-%m-%d %H:00:00')";
-
-        $result = $db->query($sql);
-        if (!is_object($result) || $result->num_rows === 0) {
-            return [];
-        }
-
-        $rows = [];
-        while ($row = $result->fetch_assoc()) {
-            $rows[] = [
-                'department_id' => (int)($row['department_id'] ?? 0),
-                'hour_bucket' => (string)($row['hour_bucket'] ?? ''),
-                'wash_count' => (int)($row['wash_count'] ?? 0),
-            ];
-        }
-
-        return $rows;
+        return (new department_wash_count_service())->countByHourForDepartments($date_start, $date_end, $department_ids);
     }
 
     /**
diff --git a/services/nginx/app/tests/Integration/DailyReports/DepartmentWashCountServiceIntegrationTest.php b/services/nginx/app/tests/Integration/DailyReports/DepartmentWashCountServiceIntegrationTest.php
new file mode 100644
index 00000000..33b18c9c
--- /dev/null
+++ b/services/nginx/app/tests/Integration/DailyReports/DepartmentWashCountServiceIntegrationTest.php
@@ -0,0 +1,267 @@
+<?php
+
+use classes\db;
+use classes\department_wash_count_service;
+
+function department_wash_count_integration_db(): db
+{
+    if (!integration_enabled()) {
+        test()->markTestSkipped('Set RUN_INTEGRATION_TESTS=1 to run DB integration tests.');
+    }
+
+    $host = getenv('CONFIG_DB_HOST') ?: null;
+    $user = getenv('CONFIG_DB_USER') ?: null;
+    $password = getenv('CONFIG_DB_PASSWORD') ?: '';
+    $database = getenv('CONFIG_DB_DATABASE') ?: null;
+    if (!$host || !$user || !$database) {
+        test()->markTestSkipped('Missing DB env vars: CONFIG_DB_HOST/CONFIG_DB_USER/CONFIG_DB_DATABASE.');
+    }
+
+    app_require('classes/db.php');
+    app_require('classes/department_wash_count_service.php');
+
+    $db = new db([
+        'host' => $host,
+        'user' => $user,
+        'password' => $password,
+        'database' => $database,
+        'port' => (int)(getenv('CONFIG_DB_PORT') ?: 3306),
+    ]);
+    $db->connect();
+    $GLOBALS['db'] = $db;
+
+    department_wash_count_prepare_tables($db);
+
+    return $db;
+}
+
+function department_wash_count_prepare_tables(db $db): void
+{
+    $db->query(
+        'CREATE TABLE IF NOT EXISTS department_lanes (
+            id INT AUTO_INCREMENT PRIMARY KEY,
+            department_id INT NULL,
+            name VARCHAR(255) NULL,
+            dynamic_image_id INT NULL,
+            selfserve_enabled TINYINT(1) NOT NULL DEFAULT 0
+        )'
+    );
+
+    $db->query(
+        'CREATE TABLE IF NOT EXISTS department_selfserve_conditions (
+            id INT AUTO_INCREMENT PRIMARY KEY,
+            department_id INT NULL,
+            name VARCHAR(255) NULL,
+            product INT NULL,
+            action VARCHAR(64) NULL,
+            order_index INT NOT NULL DEFAULT 0,
+            deleted_at DATETIME NULL
+        )'
+    );
+
+    $db->query(
+        'CREATE TABLE IF NOT EXISTS department_selfserve_tasks (
+            id INT AUTO_INCREMENT PRIMARY KEY,
+            condition_id INT NULL,
+            product INT NULL,
+            description TEXT NULL,
+            task VARCHAR(64) NULL,
+            buttons TEXT NULL,
+            order_index INT NOT NULL DEFAULT 0,
+            deleted_at DATETIME NULL
+        )'
+    );
+
+    $db->query(
+        'CREATE TABLE IF NOT EXISTS products (
+            id INT AUTO_INCREMENT PRIMARY KEY,
+            name VARCHAR(255) NOT NULL,
+            description TEXT NULL,
+            price INT NOT NULL DEFAULT 0,
+            is_wash TINYINT(1) NOT NULL DEFAULT 0,
+            created_at DATETIME NULL DEFAULT CURRENT_TIMESTAMP,
+            updated_at DATETIME NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
+        )'
+    );
+
+    $db->query(
+        'CREATE TABLE IF NOT EXISTS orders (
+            id INT AUTO_INCREMENT PRIMARY KEY,
+            customer_id INT NOT NULL,
+            cashier_id INT NOT NULL,
+            reference VARCHAR(255) NULL,
+            notes TEXT NULL,
+            department_id INT NOT NULL,
+            reg_1 VARCHAR(64) NULL,
+            reg_2 VARCHAR(64) NULL,
+            reg_3 VARCHAR(64) NULL,
+            created_at DATETIME NOT NULL,
+            include_in_invoice TINYINT(1) NULL,
+            wash_id VARCHAR(255) NULL,
+            deleted_at DATETIME NULL
+        )'
+    );
+
+    $db->query(
+        'CREATE TABLE IF NOT EXISTS order_items (
+            id INT AUTO_INCREMENT PRIMARY KEY,
+            order_id INT NOT NULL,
+            product_id INT NOT NULL,
+            reference VARCHAR(255) NULL,
+            notes TEXT NULL,
+            cashier_id INT NOT NULL,
+            price DECIMAL(10,2) NOT NULL DEFAULT 0,
+            quantity INT NOT NULL DEFAULT 1,
+            deleted_at DATETIME NULL
+        )'
+    );
+
+    $db->query(
+        'CREATE TABLE IF NOT EXISTS selfserve_wash_sessions (
+            id INT AUTO_INCREMENT PRIMARY KEY,
+            lane_id INT NOT NULL,
+            department_id INT NOT NULL,
+            reg VARCHAR(64) NOT NULL,
+            status VARCHAR(64) NOT NULL,
+            allowed TINYINT(1) NOT NULL DEFAULT 0,
+            wash_started_at DATETIME NULL,
+            machine_start_triggered_at DATETIME NULL,
+            order_id INT NULL,
+            completed_at DATETIME NULL,
+            created_at DATETIME NULL,
+            deleted_at DATETIME NULL
+        )'
+    );
+}
+
+function department_wash_count_insert_product(db $db, string $suffix, bool $isWash): int
+{
+    $productNameColumn = null;
+    if ($db->num_rows($db->query("SHOW COLUMNS FROM products LIKE 'name'")) > 0) {
+        $productNameColumn = 'name';
+    } elseif ($db->num_rows($db->query("SHOW COLUMNS FROM products LIKE 'title'")) > 0) {
+        $productNameColumn = 'title';
+    } else {
+        test()->markTestSkipped('Products table is missing both name and title columns required by this integration test.');
+    }
+
+    $escapedName = $db->escape_string('Wash count product ' . $suffix . ' ' . ($isWash ? 'wash' : 'minute'));
+    $descriptionSql = $db->num_rows($db->query("SHOW COLUMNS FROM products LIKE 'description'")) > 0
+        ? ', description'
+        : '';
+    $descriptionValueSql = $descriptionSql !== '' ? ", 'Integration wash count product'" : '';
+
+    $db->query(
+        "INSERT INTO products ($productNameColumn$descriptionSql, is_wash)
+         VALUES ('$escapedName'$descriptionValueSql, " . ($isWash ? '1' : '0') . ')'
+    );
+
+    return (int)$db->insert_id();
+}
+
+function department_wash_count_insert_order(db $db, int $departmentId, int $productId, string $reference, string $createdAt, int $price = 100): int
+{
+    $escapedReference = $db->escape_string($reference);
+    $escapedCreatedAt = $db->escape_string($createdAt);
+
+    $db->query(
+        "INSERT INTO orders (customer_id, cashier_id, reference, notes, department_id, reg_1, reg_2, reg_3, created_at)
+         VALUES (1, 1, '$escapedReference', 'Integration test', $departmentId, 'COUNT$departmentId', '', '', '$escapedCreatedAt')"
+    );
+    $orderId = (int)$db->insert_id();
+
+    $db->query(
+        "INSERT INTO order_items (order_id, product_id, reference, notes, cashier_id, price, quantity)
+         VALUES ($orderId, $productId, '$escapedReference', 'Integration test', 1, $price, 1)"
+    );
+
+    return $orderId;
+}
+
+function department_wash_count_insert_session(
+    db $db,
+    int $departmentId,
+    string $reg,
+    string $status,
+    ?string $completedAt,
+    ?int $orderId = null
+): int {
+    $escapedReg = $db->escape_string($reg);
+    $escapedStatus = $db->escape_string($status);
+    $completedAtSql = $completedAt === null ? 'NULL' : "'" . $db->escape_string($completedAt) . "'";
+    $orderIdSql = $orderId === null ? 'NULL' : (string)$orderId;
+
+    $db->query(
+        "INSERT INTO selfserve_wash_sessions (lane_id, department_id, reg, status, allowed, wash_started_at, machine_start_triggered_at, order_id, completed_at, created_at)
+         VALUES (1, $departmentId, '$escapedReg', '$escapedStatus', 1, NULL, NULL, $orderIdSql, $completedAtSql, $completedAtSql)"
+    );
+
+    return (int)$db->insert_id();
+}
+
+it('counts completed self-serve minute billing sessions site-wide and dedupes linked wash orders', function (): void {
+    $db = department_wash_count_integration_db();
+    $service = new department_wash_count_service();
+    $suffix = (string)random_int(10000, 99999);
+    $departmentId = 700000 + (int)$suffix;
+    $orderIds = [];
+    $productIds = [];
+    $sessionIds = [];
+
+    try {
+        $washProductId = department_wash_count_insert_product($db, $suffix, true);
+        $minuteProductId = department_wash_count_insert_product($db, $suffix, false);
+        $productIds = [$washProductId, $minuteProductId];
+
+        $orderIds[] = department_wash_count_insert_order($db, $departmentId, $washProductId, 'plain-wash-' . $suffix, '2026-04-01 10:15:00', 100);
+        $linkedMinuteOrderId = department_wash_count_insert_order($db, $departmentId, $minuteProductId, 'linked-minute-' . $suffix, '2026-04-01 11:10:00', 25);
+        $orderIds[] = $linkedMinuteOrderId;
+        $linkedWashOrderId = department_wash_count_insert_order($db, $departmentId, $washProductId, 'linked-wash-' . $suffix, '2026-04-01 13:05:00', 100);
+        $orderIds[] = $linkedWashOrderId;
+        $orderIds[] = department_wash_count_insert_order($db, $departmentId, $minuteProductId, 'plain-minute-' . $suffix, '2026-04-01 14:00:00', 25);
+
+        $sessionIds[] = department_wash_count_insert_session($db, $departmentId, 'LINKMIN' . $suffix, 'COMPLETED', '2026-04-01 12:00:00', $linkedMinuteOrderId);
+        $sessionIds[] = department_wash_count_insert_session($db, $departmentId, 'STAND' . $suffix, 'COMPLETED', '2026-04-01 12:20:00');
+        $sessionIds[] = department_wash_count_insert_session($db, $departmentId, 'LINKWASH' . $suffix, 'COMPLETED', '2026-04-01 13:30:00', $linkedWashOrderId);
+        $sessionIds[] = department_wash_count_insert_session($db, $departmentId, 'FORCE' . $suffix, 'FORCE_STOPPED', '2026-04-01 15:00:00');
+        $sessionIds[] = department_wash_count_insert_session($db, $departmentId, 'OPEN' . $suffix, 'COMPLETED', null);
+
+        expect($service->countInDateRange('2026-04-01 00:00:00', '2026-04-01 23:59:59', $departmentId))->toBe(4);
+
+        $hourRows = $service->countByHourForDepartments('2026-04-01 00:00:00', '2026-04-01 23:59:59', [$departmentId]);
+        $countsByHour = [];
+        foreach ($hourRows as $row) {
+            $countsByHour[$row['hour_bucket']] = $row['wash_count'];
+        }
+
+        expect($countsByHour)->toMatchArray([
+            '2026-04-01 10:00:00' => 1,
+            '2026-04-01 11:00:00' => 1,
+            '2026-04-01 12:00:00' => 1,
+            '2026-04-01 13:00:00' => 1,
+        ]);
+        expect($countsByHour)->not->toHaveKey('2026-04-01 14:00:00')
+            ->and($countsByHour)->not->toHaveKey('2026-04-01 15:00:00');
+
+        $summary = $service->transactionSummary('2026-04-01 00:00:00', '2026-04-01 23:59:59', [$departmentId]);
+        expect($summary)->toMatchArray([
+            'quantity' => 4,
+            'products' => 4,
+            'earnings' => 250,
+            'washes' => 4,
+        ]);
+    } finally {
+        if ($sessionIds !== []) {
+            $db->query('DELETE FROM selfserve_wash_sessions WHERE id IN (' . implode(',', array_map('intval', $sessionIds)) . ')');
+        }
+        if ($orderIds !== []) {
+            $orderIdsSql = implode(',', array_map('intval', $orderIds));
+            $db->query("DELETE FROM order_items WHERE order_id IN ($orderIdsSql)");
+            $db->query("DELETE FROM orders WHERE id IN ($orderIdsSql)");
+        }
+        if ($productIds !== []) {
+            $db->query('DELETE FROM products WHERE id IN (' . implode(',', array_map('intval', $productIds)) . ')');
+        }
+        $db->close();
+    }
+});
diff --git a/services/nginx/app/tests/Support/Api/ApiSchemaBootstrap.php b/services/nginx/app/tests/Support/Api/ApiSchemaBootstrap.php
index fd22006b..e7ad3d3a 100644
--- a/services/nginx/app/tests/Support/Api/ApiSchemaBootstrap.php
+++ b/services/nginx/app/tests/Support/Api/ApiSchemaBootstrap.php
@@ -361,7 +361,9 @@ CREATE TABLE IF NOT EXISTS `selfserve_wash_sessions` (
     PRIMARY KEY (`id`),
     KEY `idx_selfserve_wash_sessions_lane_reg` (`lane_id`, `reg`),
     KEY `idx_selfserve_wash_sessions_status` (`status`),
-    KEY `idx_selfserve_wash_sessions_customer` (`customer_number`)
+    KEY `idx_selfserve_wash_sessions_customer` (`customer_number`),
+    KEY `idx_selfserve_wash_sessions_department_completed` (`department_id`, `completed_at`),
+    KEY `idx_selfserve_wash_sessions_order` (`order_id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
 SQL,
             'selfserve_wash_session_answers' => <<<'SQL'
diff --git a/services/nginx/app/tests/Unit/DailyReports/DepartmentDailyReportsOverviewRouteTest.php b/services/nginx/app/tests/Unit/DailyReports/DepartmentDailyReportsOverviewRouteTest.php
index 56df03b4..a8ecf4d2 100644
--- a/services/nginx/app/tests/Unit/DailyReports/DepartmentDailyReportsOverviewRouteTest.php
+++ b/services/nginx/app/tests/Unit/DailyReports/DepartmentDailyReportsOverviewRouteTest.php
@@ -392,5 +392,8 @@ it('wires the overview route to batched repository methods and overview path', f
     expect($routeContent)->toContain('/departments/daily-reports/outside-hours-trend');
     expect($routeContent)->toContain('getTransactionSummaryForDepartments');
     expect($routeContent)->toContain('normalizeDepartmentIdsParameter');
+    expect($objectContent)->toContain('department_wash_count_service');
+    expect($objectContent)->toContain('countInDateRange');
+    expect($objectContent)->toContain('listTransactions');
     expect($objectContent)->toContain('public function getBookingSummaryForDepartments');
 });
diff --git a/services/nginx/app/tests/Unit/DailyReports/DepartmentWashCountServiceTest.php b/services/nginx/app/tests/Unit/DailyReports/DepartmentWashCountServiceTest.php
new file mode 100644
index 00000000..aecd09f5
--- /dev/null
+++ b/services/nginx/app/tests/Unit/DailyReports/DepartmentWashCountServiceTest.php
@@ -0,0 +1,138 @@
+<?php
+
+app_require('classes/department_wash_count_service.php');
+
+use classes\department_wash_count_service;
+
+final class DepartmentWashCountFakeResult
+{
+    public int $num_rows;
+    private int $cursor = 0;
+
+    public function __construct(private readonly array $rows)
+    {
+        $this->num_rows = count($rows);
+    }
+
+    public function fetch_assoc(): ?array
+    {
+        if (!array_key_exists($this->cursor, $this->rows)) {
+            return null;
+        }
+
+        return $this->rows[$this->cursor++];
+    }
+}
+
+final class DepartmentWashCountFakeDb
+{
+    public array $queries = [];
+
+    public function escape_string(string $value): string
+    {
+        return addslashes($value);
+    }
+
+    public function getDatabase(): string
+    {
+        return 'test_db';
+    }
+
+    public function query(string $sql): DepartmentWashCountFakeResult
+    {
+        $this->queries[] = $sql;
+
+        if (str_contains($sql, 'information_schema.COLUMNS') || str_contains($sql, 'information_schema.STATISTICS')) {
+            return new DepartmentWashCountFakeResult([['c' => 1, 'DATA_TYPE' => 'text']]);
+        }
+
+        if (str_contains($sql, 'COUNT(DISTINCT o.id) AS quantity')) {
+            return new DepartmentWashCountFakeResult([[
+                'quantity' => 3,
+                'products' => 5,
+                'earnings' => 250,
+            ]]);
+        }
+
+        return new DepartmentWashCountFakeResult([[
+            'department_id' => 7,
+            'hour_bucket' => '2026-04-01 12:00:00',
+            'wash_count' => 2,
+        ]]);
+    }
+}
+
+function department_wash_count_find_query(array $queries, string $needle): string
+{
+    foreach ($queries as $query) {
+        if (str_contains($query, $needle)) {
+            return $query;
+        }
+    }
+
+    return '';
+}
+
+it('builds wash counts from order washes and completed self-serve sessions with linked-order dedupe', function (): void {
+    $hadDb = array_key_exists('db', $GLOBALS);
+    $previousDb = $GLOBALS['db'] ?? null;
+    $fakeDb = new DepartmentWashCountFakeDb();
+    $GLOBALS['db'] = $fakeDb;
+
+    try {
+        $service = new department_wash_count_service();
+
+        $rows = $service->countByHourForDepartments('2026-04-01 00:00:00', '2026-04-01 23:59:59', [7]);
+
+        expect($rows)->toBe([[
+            'department_id' => 7,
+            'hour_bucket' => '2026-04-01 12:00:00',
+            'wash_count' => 2,
+        ]]);
+
+        $query = department_wash_count_find_query($fakeDb->queries, 'FROM selfserve_wash_sessions s');
+        expect($query)->toContain('FROM selfserve_wash_sessions s')
+            ->and($query)->toContain("UPPER(TRIM(s.status)) = 'COMPLETED'")
+            ->and($query)->toContain('s.completed_at IS NOT NULL')
+            ->and($query)->toContain('COALESCE(linked_o.created_at, s.completed_at)')
+            ->and($query)->toContain("CONCAT('order:', linked_o.id)")
+            ->and($query)->toContain('GROUP BY dedupe_key, department_id');
+    } finally {
+        if ($hadDb) {
+            $GLOBALS['db'] = $previousDb;
+        } else {
+            unset($GLOBALS['db']);
+        }
+    }
+});
+
+it('keeps transaction totals order-based while using expanded wash counts', function (): void {
+    $hadDb = array_key_exists('db', $GLOBALS);
+    $previousDb = $GLOBALS['db'] ?? null;
+    $fakeDb = new DepartmentWashCountFakeDb();
+    $GLOBALS['db'] = $fakeDb;
+
+    try {
+        $service = new department_wash_count_service();
+
+        $summary = $service->transactionSummary('2026-04-01 00:00:00', '2026-04-01 23:59:59', [7]);
+
+        expect($summary)->toBe([
+            'quantity' => 3,
+            'products' => 5,
+            'earnings' => 250,
+            'washes' => 2,
+        ]);
+        $summaryQuery = department_wash_count_find_query($fakeDb->queries, 'COUNT(DISTINCT o.id) AS quantity');
+        $countQuery = department_wash_count_find_query($fakeDb->queries, 'FROM selfserve_wash_sessions s');
+        expect($summaryQuery)->toContain('COUNT(DISTINCT o.id) AS quantity')
+            ->and($summaryQuery)->not->toContain('selfserve_wash_sessions')
+            ->and($countQuery)->toContain('selfserve_wash_sessions');
+    } finally {
+        if ($hadDb) {
+            $GLOBALS['db'] = $previousDb;
+        } else {
+            unset($GLOBALS['db']);
+        }
+    }
+});
diff --git a/services/nginx/app/tests/Unit/Selfserve/SelfserveSchemaBootstrapCompatibilityTest.php b/services/nginx/app/tests/Unit/Selfserve/SelfserveSchemaBootstrapCompatibilityTest.php
index b03cfce7..cd965f60 100644
--- a/services/nginx/app/tests/Unit/Selfserve/SelfserveSchemaBootstrapCompatibilityTest.php
+++ b/services/nginx/app/tests/Unit/Selfserve/SelfserveSchemaBootstrapCompatibilityTest.php
@@ -130,6 +130,21 @@ it('adds wash_started_at column for legacy selfserve wash session schemas', func
     expect($bootstrapContent)->toContain('ALTER TABLE selfserve_wash_sessions ADD COLUMN wash_started_at DATETIME NULL AFTER machine_start_triggered_at');
 });
 
+it('adds reporting indexes for completed self-serve wash session counts', function (): void {
+    $bootstrapContent = file_get_contents(app_path('classes/selfserve_schema_bootstrap.php'));
+    $apiSchemaContent = file_get_contents(app_path('tests/Support/Api/ApiSchemaBootstrap.php'));
+
+    expect($bootstrapContent)->not->toBeFalse()
+        ->and($apiSchemaContent)->not->toBeFalse();
+    expect($bootstrapContent)->toContain('idx_selfserve_wash_sessions_department_completed')
+        ->and($bootstrapContent)->toContain('ALTER TABLE selfserve_wash_sessions ADD INDEX idx_selfserve_wash_sessions_department_completed (department_id, completed_at)')
+        ->and($bootstrapContent)->toContain('idx_selfserve_wash_sessions_order')
+        ->and($bootstrapContent)->toContain('ALTER TABLE selfserve_wash_sessions ADD INDEX idx_selfserve_wash_sessions_order (order_id)')
+        ->and($bootstrapContent)->toContain('public static function ensureIndex');
+    expect($apiSchemaContent)->toContain('idx_selfserve_wash_sessions_department_completed')
+        ->and($apiSchemaContent)->toContain('idx_selfserve_wash_sessions_order');
+});
+
 it('adds lane-level self-serve enablement for existing department lanes', function (): void {
     $bootstrapContent = file_get_contents(app_path('classes/selfserve_schema_bootstrap.php'));
 
diff --git a/services/nginx/app/tests/Unit/Workfeed/DepartmentWeatherWorkfeedHoursTest.php b/services/nginx/app/tests/Unit/Workfeed/DepartmentWeatherWorkfeedHoursTest.php
index 2f1ec50e..27f915e1 100644
--- a/services/nginx/app/tests/Unit/Workfeed/DepartmentWeatherWorkfeedHoursTest.php
+++ b/services/nginx/app/tests/Unit/Workfeed/DepartmentWeatherWorkfeedHoursTest.php
@@ -563,5 +563,5 @@ it('wires department weather route to use batched wash aggregation', function ()
     expect($routeContent)->toContain('loadDepartmentWashCountsBySlot');
     expect($routeContent)->toContain('countWashesByHourForDepartments');
     expect($ordersContent)->toContain('public function countWashesByHourForDepartments');
-    expect($ordersContent)->toContain('GROUP BY o.department_id');
+    expect($ordersContent)->toContain('department_wash_count_service');
 });