Merge branch 'master' into tokens-payment

# Conflicts:
#	src/backend/taler-merchant-httpd_private-post-orders.c
#	src/backenddb/Makefile.am
#	src/backenddb/merchant-0006.sql
#	src/backenddb/pg_insert_token_family_key.c

32 files changed, 1526 insertions, 429 deletions

diff --git a/src/backend/Makefile.am b/src/backend/Makefile.am
index dbc7cde8..cce7faec 100644
--- a/src/backend/Makefile.am
+++ b/src/backend/Makefile.am
@@ -37,6 +37,8 @@ taler_merchant_httpd_SOURCES = \
     taler-merchant-httpd_mhd.h \
   taler-merchant-httpd_private-delete-account-ID.c \
     taler-merchant-httpd_private-delete-account-ID.h \
+  taler-merchant-httpd_private-delete-categories-ID.c \
+    taler-merchant-httpd_private-delete-categories-ID.h \
   taler-merchant-httpd_private-delete-instances-ID.c \
     taler-merchant-httpd_private-delete-instances-ID.h \
   taler-merchant-httpd_private-delete-instances-ID-token.c \
@@ -59,12 +61,18 @@ taler_merchant_httpd_SOURCES = \
     taler-merchant-httpd_private-get-accounts.h \
   taler-merchant-httpd_private-get-accounts-ID.c \
     taler-merchant-httpd_private-get-accounts-ID.h \
+  taler-merchant-httpd_private-get-categories.c \
+    taler-merchant-httpd_private-get-categories.h \
+  taler-merchant-httpd_private-get-categories-ID.c \
+    taler-merchant-httpd_private-get-categories-ID.h \
   taler-merchant-httpd_private-get-instances.c \
     taler-merchant-httpd_private-get-instances.h \
   taler-merchant-httpd_private-get-instances-ID.c \
     taler-merchant-httpd_private-get-instances-ID.h \
   taler-merchant-httpd_private-get-instances-ID-kyc.c \
     taler-merchant-httpd_private-get-instances-ID-kyc.h \
+  taler-merchant-httpd_private-get-pos.c \
+    taler-merchant-httpd_private-get-pos.h \
   taler-merchant-httpd_private-get-products.c \
     taler-merchant-httpd_private-get-products.h \
   taler-merchant-httpd_private-get-products-ID.c \
@@ -93,6 +101,8 @@ taler_merchant_httpd_SOURCES = \
     taler-merchant-httpd_private-get-webhooks-ID.h \
   taler-merchant-httpd_private-patch-accounts-ID.c \
     taler-merchant-httpd_private-patch-accounts-ID.h \
+  taler-merchant-httpd_private-patch-categories-ID.c \
+    taler-merchant-httpd_private-patch-categories-ID.h \
   taler-merchant-httpd_private-patch-instances-ID.c \
     taler-merchant-httpd_private-patch-instances-ID.h \
   taler-merchant-httpd_private-patch-orders-ID-forget.c \
@@ -109,6 +119,8 @@ taler_merchant_httpd_SOURCES = \
     taler-merchant-httpd_private-patch-webhooks-ID.h \
   taler-merchant-httpd_private-post-account.c \
     taler-merchant-httpd_private-post-account.h \
+  taler-merchant-httpd_private-post-categories.c \
+    taler-merchant-httpd_private-post-categories.h \
   taler-merchant-httpd_private-post-instances.c \
     taler-merchant-httpd_private-post-instances.h \
   taler-merchant-httpd_private-post-instances-ID-auth.c \
diff --git a/src/backend/taler-merchant-exchange.c b/src/backend/taler-merchant-exchange.c
index 7945cb50..72566e9b 100644
--- a/src/backend/taler-merchant-exchange.c
+++ b/src/backend/taler-merchant-exchange.c
@@ -32,8 +32,8 @@
  * long-polling and do not want to wake up too often.
  */
 #define EXCHANGE_TIMEOUT GNUNET_TIME_relative_multiply ( \
-    GNUNET_TIME_UNIT_MINUTES, \
-    30)
+          GNUNET_TIME_UNIT_MINUTES, \
+          30)
 
 /**
  * How many inquiries do we process concurrently at most.
@@ -1154,7 +1154,8 @@ find_work (void *cls)
       return;
     }
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-                "No open inquiries found, waiting for notification to resume\n");
+                "No open inquiries found, waiting for notification to resume\n")
+    ;
   }
 }
 
@@ -1215,7 +1216,7 @@ run (void *cls,
   {
     GNUNET_break (0);
     GNUNET_SCHEDULER_shutdown ();
-    global_ret = EXIT_NO_RESTART;
+    global_ret = EXIT_FAILURE;
     return;
   }
   if (NULL ==
@@ -1233,7 +1234,7 @@ run (void *cls,
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                 "Failed to connect to database\n");
     GNUNET_SCHEDULER_shutdown ();
-    global_ret = EXIT_NO_RESTART;
+    global_ret = EXIT_FAILURE;
     return;
   }
   {
diff --git a/src/backend/taler-merchant-httpd.c b/src/backend/taler-merchant-httpd.c
index 95ba9bf1..a7c1cbb4 100644
--- a/src/backend/taler-merchant-httpd.c
+++ b/src/backend/taler-merchant-httpd.c
@@ -34,6 +34,7 @@
 #include "taler-merchant-httpd_get-templates-ID.h"
 #include "taler-merchant-httpd_mhd.h"
 #include "taler-merchant-httpd_private-delete-account-ID.h"
+#include "taler-merchant-httpd_private-delete-categories-ID.h"
 #include "taler-merchant-httpd_private-delete-instances-ID.h"
 #include "taler-merchant-httpd_private-delete-instances-ID-token.h"
 #include "taler-merchant-httpd_private-delete-products-ID.h"
@@ -45,9 +46,12 @@
 #include "taler-merchant-httpd_private-delete-webhooks-ID.h"
 #include "taler-merchant-httpd_private-get-accounts.h"
 #include "taler-merchant-httpd_private-get-accounts-ID.h"
+#include "taler-merchant-httpd_private-get-categories.h"
+#include "taler-merchant-httpd_private-get-categories-ID.h"
 #include "taler-merchant-httpd_private-get-instances.h"
 #include "taler-merchant-httpd_private-get-instances-ID.h"
 #include "taler-merchant-httpd_private-get-instances-ID-kyc.h"
+#include "taler-merchant-httpd_private-get-pos.h"
 #include "taler-merchant-httpd_private-get-products.h"
 #include "taler-merchant-httpd_private-get-products-ID.h"
 #include "taler-merchant-httpd_private-get-orders.h"
@@ -62,6 +66,7 @@
 #include "taler-merchant-httpd_private-get-webhooks.h"
 #include "taler-merchant-httpd_private-get-webhooks-ID.h"
 #include "taler-merchant-httpd_private-patch-accounts-ID.h"
+#include "taler-merchant-httpd_private-patch-categories-ID.h"
 #include "taler-merchant-httpd_private-patch-instances-ID.h"
 #include "taler-merchant-httpd_private-patch-orders-ID-forget.h"
 #include "taler-merchant-httpd_private-patch-otp-devices-ID.h"
@@ -70,6 +75,7 @@
 #include "taler-merchant-httpd_private-patch-token-families-SLUG.h"
 #include "taler-merchant-httpd_private-patch-webhooks-ID.h"
 #include "taler-merchant-httpd_private-post-account.h"
+#include "taler-merchant-httpd_private-post-categories.h"
 #include "taler-merchant-httpd_private-post-instances.h"
 #include "taler-merchant-httpd_private-post-instances-ID-auth.h"
 #include "taler-merchant-httpd_private-post-instances-ID-token.h"
@@ -932,6 +938,52 @@ url_handler (void *cls,
       .method = MHD_HTTP_METHOD_GET,
       .handler = &TMH_private_get_instances_ID_kyc,
     },
+    /* GET /pos: */
+    {
+      .url_prefix = "/pos",
+      .method = MHD_HTTP_METHOD_GET,
+      .handler = &TMH_private_get_pos
+    },
+    /* GET /categories: */
+    {
+      .url_prefix = "/categories",
+      .method = MHD_HTTP_METHOD_GET,
+      .handler = &TMH_private_get_categories
+    },
+    /* POST /categories: */
+    {
+      .url_prefix = "/categories",
+      .method = MHD_HTTP_METHOD_POST,
+      .handler = &TMH_private_post_categories,
+      /* allow category data of up to 8 kb, that should be plenty */
+      .max_upload = 1024 * 8
+    },
+    /* GET /categories/$ID: */
+    {
+      .url_prefix = "/categories/",
+      .method = MHD_HTTP_METHOD_GET,
+      .have_id_segment = true,
+      .allow_deleted_instance = true,
+      .handler = &TMH_private_get_categories_ID
+    },
+    /* DELETE /categories/$ID: */
+    {
+      .url_prefix = "/categories/",
+      .method = MHD_HTTP_METHOD_DELETE,
+      .have_id_segment = true,
+      .allow_deleted_instance = true,
+      .handler = &TMH_private_delete_categories_ID
+    },
+    /* PATCH /categories/$ID/: */
+    {
+      .url_prefix = "/categories/",
+      .method = MHD_HTTP_METHOD_PATCH,
+      .have_id_segment = true,
+      .allow_deleted_instance = true,
+      .handler = &TMH_private_patch_categories_ID,
+      /* allow category data of up to 8 kb, that should be plenty */
+      .max_upload = 1024 * 8
+    },
     /* GET /products: */
     {
       .url_prefix = "/products",
@@ -949,7 +1001,7 @@ url_handler (void *cls,
          in the code... */
       .max_upload = 1024 * 1024 * 8
     },
-    /* GET /products/$ID/: */
+    /* GET /products/$ID: */
     {
       .url_prefix = "/products/",
       .method = MHD_HTTP_METHOD_GET,
diff --git a/src/backend/taler-merchant-httpd_config.c b/src/backend/taler-merchant-httpd_config.c
index 3777904f..10f0cd39 100644
--- a/src/backend/taler-merchant-httpd_config.c
+++ b/src/backend/taler-merchant-httpd_config.c
@@ -42,7 +42,7 @@
  * #MERCHANT_PROTOCOL_CURRENT and #MERCHANT_PROTOCOL_AGE in
  * merchant_api_config.c!
  */
-#define MERCHANT_PROTOCOL_VERSION "14:0:10"
+#define MERCHANT_PROTOCOL_VERSION "16:0:12"
 
 
 /**
@@ -82,14 +82,20 @@ MH_handler_config (struct TMH_RequestHandler *rh,
                    struct TMH_HandlerContext *hc)
 {
   static struct MHD_Response *response;
+  static struct GNUNET_TIME_Absolute a;
 
   (void) rh;
   (void) hc;
+  if ( (GNUNET_TIME_absolute_is_past (a)) &&
+       (NULL != response) )
+  {
+    MHD_destroy_response (response);
+    response = NULL;
+  }
   if (NULL == response)
   {
     json_t *specs = json_object ();
     json_t *exchanges = json_array ();
-    struct GNUNET_TIME_Absolute a;
     struct GNUNET_TIME_Timestamp km;
     char dat[128];
 
diff --git a/src/backend/taler-merchant-httpd_contract.h b/src/backend/taler-merchant-httpd_contract.h
index 006d0205..6389cc70 100644
--- a/src/backend/taler-merchant-httpd_contract.h
+++ b/src/backend/taler-merchant-httpd_contract.h
@@ -367,7 +367,7 @@ struct TALER_MerchantContractTokenFamily
 };
 
 /**
- * Struct to hold contract terms in v0 and v1 format. v0 contracts are mdoelled
+ * Struct to hold contract terms in v0 and v1 format. v0 contracts are modelled
  * as a v1 contract with a single choice and no inputs and outputs. Use the
  * version field to explicitly differentiate between v0 and v1 contracts.
  */
diff --git a/src/backend/taler-merchant-httpd_mhd.c b/src/backend/taler-merchant-httpd_mhd.c
index e96acca5..0bb22b35 100644
--- a/src/backend/taler-merchant-httpd_mhd.c
+++ b/src/backend/taler-merchant-httpd_mhd.c
@@ -59,6 +59,7 @@ TMH_MHD_test_html_desired (struct MHD_Connection *connection)
   bool ret = false;
   const char *accept;
 
+  // FIXME: use TALER_MHD_check_accept here!
   accept = MHD_lookup_connection_value (connection,
                                         MHD_HEADER_KIND,
                                         MHD_HTTP_HEADER_ACCEPT);
diff --git a/src/backend/taler-merchant-httpd_private-delete-categories-ID.c b/src/backend/taler-merchant-httpd_private-delete-categories-ID.c
new file mode 100644
index 00000000..892dbd9c
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_private-delete-categories-ID.c
@@ -0,0 +1,92 @@
+/*
+  This file is part of TALER
+  (C) 2024 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU Affero General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file taler-merchant-httpd_private-delete-categories-ID.c
+ * @brief implement DELETE /private/categories/$ID
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "taler-merchant-httpd_private-delete-categories-ID.h"
+#include <taler/taler_json_lib.h>
+
+
+/**
+ * Handle a DELETE "/categories/$ID" request.
+ *
+ * @param rh context of the handler
+ * @param connection the MHD connection to handle
+ * @param[in,out] hc context with further information about the request
+ * @return MHD result code
+ */
+MHD_RESULT
+TMH_private_delete_categories_ID (
+  const struct TMH_RequestHandler *rh,
+  struct MHD_Connection *connection,
+  struct TMH_HandlerContext *hc)
+{
+  struct TMH_MerchantInstance *mi = hc->instance;
+  enum GNUNET_DB_QueryStatus qs;
+  unsigned long long cnum;
+  char dummy;
+
+  (void) rh;
+  GNUNET_assert (NULL != mi);
+  GNUNET_assert (NULL != hc->infix);
+  if (1 != sscanf (hc->infix,
+                   "%llu%c",
+                   &cnum,
+                   &dummy))
+  {
+    GNUNET_break_op (0);
+    return TALER_MHD_reply_with_error (connection,
+                                       MHD_HTTP_BAD_REQUEST,
+                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                       "category_id must be a number");
+  }
+  qs = TMH_db->delete_category (TMH_db->cls,
+                                mi->settings.id,
+                                cnum);
+  switch (qs)
+  {
+  case GNUNET_DB_STATUS_HARD_ERROR:
+    return TALER_MHD_reply_with_error (connection,
+                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                       TALER_EC_GENERIC_DB_STORE_FAILED,
+                                       "delete_category");
+  case GNUNET_DB_STATUS_SOFT_ERROR:
+    GNUNET_break (0);
+    return TALER_MHD_reply_with_error (connection,
+                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                       TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
+                                       "delete_category");
+  case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
+    return TALER_MHD_reply_with_error (connection,
+                                       MHD_HTTP_NOT_FOUND,
+                                       TALER_EC_MERCHANT_GENERIC_CATEGORY_UNKNOWN,
+                                       hc->infix);
+  case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
+    return TALER_MHD_reply_static (connection,
+                                   MHD_HTTP_NO_CONTENT,
+                                   NULL,
+                                   NULL,
+                                   0);
+  }
+  GNUNET_assert (0);
+  return MHD_NO;
+}
+
+
+/* end of taler-merchant-httpd_private-delete-categories-ID.c */
diff --git a/src/backend/taler-merchant-httpd_private-delete-categories-ID.h b/src/backend/taler-merchant-httpd_private-delete-categories-ID.h
new file mode 100644
index 00000000..b17eed49
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_private-delete-categories-ID.h
@@ -0,0 +1,42 @@
+/*
+  This file is part of TALER
+  (C) 2024 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU Affero General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file taler-merchant-httpd_private-delete-categories-ID.h
+ * @brief implement DELETE /private/categories/$ID/
+ * @author Christian Grothoff
+ */
+#ifndef TALER_MERCHANT_HTTPD_PRIVATE_DELETE_CATEGORIES_ID_H
+#define TALER_MERCHANT_HTTPD_PRIVATE_DELETE_CATEGORIES_ID_H
+
+#include "taler-merchant-httpd.h"
+
+
+/**
+ * Handle a DELETE "/categories/$ID" request.
+ *
+ * @param rh context of the handler
+ * @param connection the MHD connection to handle
+ * @param[in,out] hc context with further information about the request
+ * @return MHD result code
+ */
+MHD_RESULT
+TMH_private_delete_categories_ID (
+  const struct TMH_RequestHandler *rh,
+  struct MHD_Connection *connection,
+  struct TMH_HandlerContext *hc);
+
+/* end of taler-merchant-httpd_private-delete-categories-ID.h */
+#endif
diff --git a/src/backend/taler-merchant-httpd_private-delete-otp-devices-ID.c b/src/backend/taler-merchant-httpd_private-delete-otp-devices-ID.c
index b147b84f..ff9ad2ef 100644
--- a/src/backend/taler-merchant-httpd_private-delete-otp-devices-ID.c
+++ b/src/backend/taler-merchant-httpd_private-delete-otp-devices-ID.c
@@ -61,7 +61,7 @@ TMH_private_delete_otp_devices_ID (const struct TMH_RequestHandler *rh,
   case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
     return TALER_MHD_reply_with_error (connection,
                                        MHD_HTTP_NOT_FOUND,
-                                       TALER_EC_MERCHANT_GENERIC_TEMPLATE_UNKNOWN,
+                                       TALER_EC_MERCHANT_GENERIC_OTP_DEVICE_UNKNOWN,
                                        hc->infix);
   case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
     return TALER_MHD_reply_static (connection,
diff --git a/src/backend/taler-merchant-httpd_private-delete-products-ID.c b/src/backend/taler-merchant-httpd_private-delete-products-ID.c
index 7d314785..23b6de3c 100644
--- a/src/backend/taler-merchant-httpd_private-delete-products-ID.c
+++ b/src/backend/taler-merchant-httpd_private-delete-products-ID.c
@@ -59,22 +59,30 @@ TMH_private_delete_products_ID (const struct TMH_RequestHandler *rh,
                                        TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
                                        "delete_product (soft)");
   case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
-    /* check if deletion must have failed because of locks by
-       checking if the product exists */
-    qs = TMH_db->lookup_product (TMH_db->cls,
-                                 mi->settings.id,
-                                 hc->infix,
-                                 NULL);
-    if (GNUNET_DB_STATUS_HARD_ERROR == qs)
-      return TALER_MHD_reply_with_error (connection,
-                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                         TALER_EC_GENERIC_DB_STORE_FAILED,
-                                         "lookup_product");
-    if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
-      return TALER_MHD_reply_with_error (connection,
-                                         MHD_HTTP_NOT_FOUND,
-                                         TALER_EC_MERCHANT_GENERIC_PRODUCT_UNKNOWN,
-                                         hc->infix);
+    {
+      size_t num_categories = 0;
+      uint64_t *categories = NULL;
+
+      /* check if deletion must have failed because of locks by
+         checking if the product exists */
+      qs = TMH_db->lookup_product (TMH_db->cls,
+                                   mi->settings.id,
+                                   hc->infix,
+                                   NULL,
+                                   &num_categories,
+                                   &categories);
+      if (GNUNET_DB_STATUS_HARD_ERROR == qs)
+        return TALER_MHD_reply_with_error (connection,
+                                           MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                           TALER_EC_GENERIC_DB_STORE_FAILED,
+                                           "lookup_product");
+      if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
+        return TALER_MHD_reply_with_error (connection,
+                                           MHD_HTTP_NOT_FOUND,
+                                           TALER_EC_MERCHANT_GENERIC_PRODUCT_UNKNOWN,
+                                           hc->infix);
+      GNUNET_free (categories);
+    }
     return TALER_MHD_reply_with_error (
       connection,
       MHD_HTTP_CONFLICT,
diff --git a/src/backend/taler-merchant-httpd_private-get-categories-ID.c b/src/backend/taler-merchant-httpd_private-get-categories-ID.c
new file mode 100644
index 00000000..02ef3495
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_private-get-categories-ID.c
@@ -0,0 +1,119 @@
+/*
+  This file is part of TALER
+  (C) 2022-2024 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU Affero General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file taler-merchant-httpd_private-get-categories-ID.c
+ * @brief implement GET /private/categories/$ID
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "taler-merchant-httpd_private-get-categories-ID.h"
+#include <taler/taler_json_lib.h>
+
+
+/**
+ * Handle a GET "/private/categories/$ID" request.
+ *
+ * @param rh context of the handler
+ * @param connection the MHD connection to handle
+ * @param[in,out] hc context with further information about the request
+ * @return MHD result code
+ */
+MHD_RESULT
+TMH_private_get_categories_ID (
+  const struct TMH_RequestHandler *rh,
+  struct MHD_Connection *connection,
+  struct TMH_HandlerContext *hc)
+{
+  struct TMH_MerchantInstance *mi = hc->instance;
+  enum GNUNET_DB_QueryStatus qs;
+  unsigned long long cnum;
+  char dummy;
+  struct TALER_MERCHANTDB_CategoryDetails cd;
+
+  GNUNET_assert (NULL != mi);
+  GNUNET_assert (NULL != hc->infix);
+  if (1 != sscanf (hc->infix,
+                   "%llu%c",
+                   &cnum,
+                   &dummy))
+  {
+    GNUNET_break_op (0);
+    return TALER_MHD_reply_with_error (connection,
+                                       MHD_HTTP_BAD_REQUEST,
+                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                       "category_id must be a number");
+  }
+
+  qs = TMH_db->select_category (TMH_db->cls,
+                                mi->settings.id,
+                                cnum,
+                                &cd);
+  if (0 > qs)
+  {
+    GNUNET_break (0);
+    return TALER_MHD_reply_with_error (connection,
+                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                       TALER_EC_GENERIC_DB_FETCH_FAILED,
+                                       "select_category");
+  }
+  if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
+  {
+    return TALER_MHD_reply_with_error (connection,
+                                       MHD_HTTP_NOT_FOUND,
+                                       TALER_EC_MERCHANT_GENERIC_CATEGORY_UNKNOWN,
+                                       hc->infix);
+  }
+  {
+    MHD_RESULT ret;
+    json_t *products;
+
+    products = json_array ();
+    GNUNET_assert (NULL != products);
+    for (unsigned int i = 0; i<cd.num_products; i++)
+    {
+      const struct TALER_MERCHANTDB_ProductSummary *product
+        = &cd.products[i];
+      json_t *jprod;
+
+      jprod = GNUNET_JSON_PACK (
+        GNUNET_JSON_pack_string ("product_id",
+                                 product->product_id),
+        GNUNET_JSON_pack_string ("description",
+                                 product->description),
+        GNUNET_JSON_pack_object_steal ("description_i18n",
+                                       product->description_i18n));
+      GNUNET_assert (0 ==
+                     json_array_append_new (products,
+                                            jprod));
+    }
+
+    ret = TALER_MHD_REPLY_JSON_PACK (
+      connection,
+      MHD_HTTP_OK,
+      GNUNET_JSON_pack_string ("name",
+                               cd.category_name),
+      GNUNET_JSON_pack_allow_null (
+        GNUNET_JSON_pack_object_incref ("name_i18n",
+                                        cd.category_name_i18n)),
+      GNUNET_JSON_pack_array_steal ("products",
+                                    products));
+    TALER_MERCHANTDB_category_details_free (&cd);
+    return ret;
+  }
+}
+
+
+/* end of taler-merchant-httpd_private-get-categories-ID.c */
diff --git a/src/backend/taler-merchant-httpd_private-get-categories-ID.h b/src/backend/taler-merchant-httpd_private-get-categories-ID.h
new file mode 100644
index 00000000..c0226659
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_private-get-categories-ID.h
@@ -0,0 +1,42 @@
+/*
+  This file is part of TALER
+  (C) 2024 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU Affero General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file taler-merchant-httpd_private-get-categories-ID.h
+ * @brief implement GET /private/categories/$ID/
+ * @author Christian Grothoff
+ */
+#ifndef TALER_MERCHANT_HTTPD_PRIVATE_GET_CATEGORIES_ID_H
+#define TALER_MERCHANT_HTTPD_PRIVATE_GET_CATEGORIES_ID_H
+
+#include "taler-merchant-httpd.h"
+
+
+/**
+ * Handle a GET "/private/categories/$ID" request.
+ *
+ * @param rh context of the handler
+ * @param connection the MHD connection to handle
+ * @param[in,out] hc context with further information about the request
+ * @return MHD result code
+ */
+MHD_RESULT
+TMH_private_get_categories_ID (
+  const struct TMH_RequestHandler *rh,
+  struct MHD_Connection *connection,
+  struct TMH_HandlerContext *hc);
+
+/* end of taler-merchant-httpd_private-get-categories-ID.h */
+#endif
diff --git a/src/backend/taler-merchant-httpd_private-get-categories.c b/src/backend/taler-merchant-httpd_private-get-categories.c
new file mode 100644
index 00000000..8ebccb2b
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_private-get-categories.c
@@ -0,0 +1,93 @@
+/*
+  This file is part of TALER
+  (C) 2024 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU Affero General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file taler-merchant-httpd_private-get-categories.c
+ * @brief implement GET /categories
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "taler-merchant-httpd_private-get-categories.h"
+
+
+/**
+ * Add category details to our JSON array.
+ *
+ * @param cls a `json_t *` JSON array to build
+ * @param category_id ID of the category
+ * @param category_name name of the category
+ * @param category_name_i18n translations of the @a category_name
+ * @param product_count number of products in the category
+ */
+static void
+add_category (void *cls,
+              uint64_t category_id,
+              const char *category_name,
+              const json_t *category_name_i18n,
+              uint64_t product_count)
+{
+  json_t *pa = cls;
+
+  GNUNET_assert (
+    0 ==
+    json_array_append_new (
+      pa,
+      GNUNET_JSON_PACK (
+        GNUNET_JSON_pack_uint64 (
+          "category_id",
+          category_id),
+        GNUNET_JSON_pack_string (
+          "name",
+          category_name),
+        GNUNET_JSON_pack_object_incref (
+          "name_i18n",
+          (json_t *) category_name_i18n),
+        GNUNET_JSON_pack_uint64 (
+          "product_count",
+          product_count))));
+}
+
+
+MHD_RESULT
+TMH_private_get_categories (const struct TMH_RequestHandler *rh,
+                            struct MHD_Connection *connection,
+                            struct TMH_HandlerContext *hc)
+{
+  json_t *pa;
+  enum GNUNET_DB_QueryStatus qs;
+
+  pa = json_array ();
+  GNUNET_assert (NULL != pa);
+  qs = TMH_db->lookup_categories (TMH_db->cls,
+                                  hc->instance->settings.id,
+                                  &add_category,
+                                  pa);
+  if (0 > qs)
+  {
+    GNUNET_break (0);
+    json_decref (pa);
+    return TALER_MHD_reply_with_error (connection,
+                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                       TALER_EC_GENERIC_DB_FETCH_FAILED,
+                                       NULL);
+  }
+  return TALER_MHD_REPLY_JSON_PACK (connection,
+                                    MHD_HTTP_OK,
+                                    GNUNET_JSON_pack_array_steal ("categories",
+                                                                  pa));
+}
+
+
+/* end of taler-merchant-httpd_private-get-categories.c */
diff --git a/src/backend/taler-merchant-httpd_private-get-categories.h b/src/backend/taler-merchant-httpd_private-get-categories.h
new file mode 100644
index 00000000..68eed05e
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_private-get-categories.h
@@ -0,0 +1,42 @@
+/*
+  This file is part of TALER
+  (C) 2024 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU Affero General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file taler-merchant-httpd_private-get-categories.h
+ * @brief implement GET /private/categories
+ * @author Christian Grothoff
+ */
+#ifndef TALER_MERCHANT_HTTPD_PRIVATE_GET_CATEGORIES_H
+#define TALER_MERCHANT_HTTPD_PRIVATE_GET_CATEGORIES_H
+
+#include "taler-merchant-httpd.h"
+
+
+/**
+ * Handle a GET "/private/categories" request.
+ *
+ * @param rh context of the handler
+ * @param connection the MHD connection to handle
+ * @param[in,out] hc context with further information about the request
+ * @return MHD result code
+ */
+MHD_RESULT
+TMH_private_get_categories (
+  const struct TMH_RequestHandler *rh,
+  struct MHD_Connection *connection,
+  struct TMH_HandlerContext *hc);
+
+/* end of taler-merchant-httpd_private-get-categories.h */
+#endif
diff --git a/src/backend/taler-merchant-httpd_private-get-instances-ID-kyc.c b/src/backend/taler-merchant-httpd_private-get-instances-ID-kyc.c
index 8a338e7d..0382b742 100644
--- a/src/backend/taler-merchant-httpd_private-get-instances-ID-kyc.c
+++ b/src/backend/taler-merchant-httpd_private-get-instances-ID-kyc.c
@@ -684,7 +684,7 @@ kyc_with_exchange (void *cls,
     keys,
     ekr->exchange_kyc_serial,
     &h_payto,
-    ekr->kc->mi->settings.ut,
+    1, /* FIXME: this will go away! */
     GNUNET_TIME_absolute_get_remaining (kc->timeout),
     &exchange_check_cb,
     ekr);
diff --git a/src/backend/taler-merchant-httpd_private-get-instances-ID.c b/src/backend/taler-merchant-httpd_private-get-instances-ID.c
index adc99c39..c8cd2c12 100644
--- a/src/backend/taler-merchant-httpd_private-get-instances-ID.c
+++ b/src/backend/taler-merchant-httpd_private-get-instances-ID.c
@@ -79,7 +79,7 @@ get_instances_ID (struct TMH_MerchantInstance *mi,
                              mi->settings.name),
     GNUNET_JSON_pack_string (
       "user_type",
-      TALER_KYCLOGIC_kyc_user_type2s (mi->settings.ut)),
+      "business"),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_string ("website",
                                mi->settings.website)),
diff --git a/src/backend/taler-merchant-httpd_private-get-instances.c b/src/backend/taler-merchant-httpd_private-get-instances.c
index 50b5c0c2..0220d4df 100644
--- a/src/backend/taler-merchant-httpd_private-get-instances.c
+++ b/src/backend/taler-merchant-httpd_private-get-instances.c
@@ -76,7 +76,7 @@ add_instance (void *cls,
                                               mi->settings.name),
                      GNUNET_JSON_pack_string (
                        "user_type",
-                       TALER_KYCLOGIC_kyc_user_type2s (mi->settings.ut)),
+                       "business"),
                      GNUNET_JSON_pack_allow_null (
                        GNUNET_JSON_pack_string ("website",
                                                 mi->settings.website)),
diff --git a/src/backend/taler-merchant-httpd_private-get-pos.c b/src/backend/taler-merchant-httpd_private-get-pos.c
new file mode 100644
index 00000000..4c14b6ae
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_private-get-pos.c
@@ -0,0 +1,148 @@
+/*
+  This file is part of TALER
+  (C) 2019, 2020, 2021, 2024 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU Affero General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file taler-merchant-httpd_private-get-pos.c
+ * @brief implement GET /private/pos
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "taler-merchant-httpd_private-get-pos.h"
+
+
+/**
+ * Closure for add_product().
+ */
+struct Context
+{
+  /**
+   * JSON array of products we are building.
+   */
+  json_t *pa;
+
+  /**
+   * JSON array of categories we are building.
+   */
+  json_t *ca;
+
+};
+
+
+/**
+ * Add product details to our JSON array.
+ *
+ * @param ctx a `struct Context` with JSON arrays to build
+ * @param product_id ID of the product
+ */
+static void
+add_product (void *cls,
+             uint64_t product_serial,
+             const char *product_id,
+             const struct TALER_MERCHANTDB_ProductDetails *pd,
+             size_t num_categories,
+             const uint64_t *categories)
+{
+  struct Context *ctx = cls;
+  json_t *pa = ctx->pa;
+  json_t *cata;
+
+  cata = json_array ();
+  GNUNET_assert (NULL != cata);
+  for (size_t i = 0; i<num_categories; i++)
+    GNUNET_assert (
+      0 == json_array_append_new (
+        cata,
+        json_integer (categories[i])));
+  GNUNET_assert (
+    0 ==
+    json_array_append_new (
+      pa,
+      GNUNET_JSON_PACK (
+        GNUNET_JSON_pack_string ("description",
+                                 pd->description),
+        GNUNET_JSON_pack_object_incref ("description_i18n",
+                                        (json_t *) pd->description_i18n),
+        GNUNET_JSON_pack_string ("unit",
+                                 pd->unit),
+        TALER_JSON_pack_amount ("price",
+                                &pd->price),
+        GNUNET_JSON_pack_allow_null (
+          GNUNET_JSON_pack_string ("image",
+                                   pd->image)),
+        GNUNET_JSON_pack_array_steal ("categories",
+                                      cata),
+        GNUNET_JSON_pack_allow_null (
+          GNUNET_JSON_pack_array_incref ("taxes",
+                                         (json_t *) pd->taxes)),
+        (INT64_MAX == pd->total_stock)
+        ? GNUNET_JSON_pack_int64 ("total_stock",
+                                  pd->total_stock)
+        : GNUNET_JSON_pack_allow_null (
+          GNUNET_JSON_pack_string ("total_stock",
+                                   NULL)),
+        GNUNET_JSON_pack_uint64 ("minimum_age",
+                                 pd->minimum_age),
+        GNUNET_JSON_pack_uint64 ("product_serial",
+                                 product_serial),
+        GNUNET_JSON_pack_string ("product_id",
+                                 product_id))));
+}
+
+
+MHD_RESULT
+TMH_private_get_pos (const struct TMH_RequestHandler *rh,
+                     struct MHD_Connection *connection,
+                     struct TMH_HandlerContext *hc)
+{
+  struct Context ctx;
+  enum GNUNET_DB_QueryStatus qs;
+
+  ctx.pa = json_array ();
+  GNUNET_assert (NULL != ctx.pa);
+  ctx.ca = json_array ();
+  GNUNET_assert (NULL != ctx.ca);
+  GNUNET_assert (
+    0 == json_array_append_new (
+      ctx.ca,
+      GNUNET_JSON_PACK (
+        GNUNET_JSON_pack_uint64 ("id",
+                                 0),
+        GNUNET_JSON_pack_string ("name",
+                                 "default"))));
+  qs = TMH_db->lookup_all_products (TMH_db->cls,
+                                    hc->instance->settings.id,
+                                    &add_product,
+                                    &ctx);
+  if (0 > qs)
+  {
+    GNUNET_break (0);
+    json_decref (ctx.pa);
+    json_decref (ctx.ca);
+    return TALER_MHD_reply_with_error (connection,
+                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                       TALER_EC_GENERIC_DB_FETCH_FAILED,
+                                       NULL);
+  }
+  return TALER_MHD_REPLY_JSON_PACK (
+    connection,
+    MHD_HTTP_OK,
+    GNUNET_JSON_pack_array_steal ("categories",
+                                  ctx.ca),
+    GNUNET_JSON_pack_array_steal ("products",
+                                  ctx.pa));
+}
+
+
+/* end of taler-merchant-httpd_private-get-pos.c */
diff --git a/src/backend/taler-merchant-httpd_private-get-pos.h b/src/backend/taler-merchant-httpd_private-get-pos.h
new file mode 100644
index 00000000..ce266823
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_private-get-pos.h
@@ -0,0 +1,41 @@
+/*
+  This file is part of TALER
+  (C) 2024 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU Affero General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file taler-merchant-httpd_private-get-pos.h
+ * @brief implement GET /pos
+ * @author Christian Grothoff
+ */
+#ifndef TALER_MERCHANT_HTTPD_PRIVATE_GET_POS_H
+#define TALER_MERCHANT_HTTPD_PRIVATE_GET_POS_H
+
+#include "taler-merchant-httpd.h"
+
+
+/**
+ * Handle a GET "/pos" request.
+ *
+ * @param rh context of the handler
+ * @param connection the MHD connection to handle
+ * @param[in,out] hc context with further information about the request
+ * @return MHD result code
+ */
+MHD_RESULT
+TMH_private_get_pos (const struct TMH_RequestHandler *rh,
+                     struct MHD_Connection *connection,
+                     struct TMH_HandlerContext *hc);
+
+/* end of taler-merchant-httpd_private-get-pos.h */
+#endif
diff --git a/src/backend/taler-merchant-httpd_private-get-products-ID.c b/src/backend/taler-merchant-httpd_private-get-products-ID.c
index 1406349f..0729b1df 100644
--- a/src/backend/taler-merchant-httpd_private-get-products-ID.c
+++ b/src/backend/taler-merchant-httpd_private-get-products-ID.c
@@ -32,19 +32,25 @@
  * @return MHD result code
  */
 MHD_RESULT
-TMH_private_get_products_ID (const struct TMH_RequestHandler *rh,
-                             struct MHD_Connection *connection,
-                             struct TMH_HandlerContext *hc)
+TMH_private_get_products_ID (
+  const struct TMH_RequestHandler *rh,
+  struct MHD_Connection *connection,
+  struct TMH_HandlerContext *hc)
 {
   struct TMH_MerchantInstance *mi = hc->instance;
   struct TALER_MERCHANTDB_ProductDetails pd = { 0 };
   enum GNUNET_DB_QueryStatus qs;
+  size_t num_categories = 0;
+  uint64_t *categories = NULL;
+  json_t *jcategories;
 
   GNUNET_assert (NULL != mi);
   qs = TMH_db->lookup_product (TMH_db->cls,
                                mi->settings.id,
                                hc->infix,
-                               &pd);
+                               &pd,
+                               &num_categories,
+                               &categories);
   if (0 > qs)
   {
     GNUNET_break (0);
@@ -60,6 +66,16 @@ TMH_private_get_products_ID (const struct TMH_RequestHandler *rh,
                                        TALER_EC_MERCHANT_GENERIC_PRODUCT_UNKNOWN,
                                        hc->infix);
   }
+  jcategories = json_array ();
+  GNUNET_assert (NULL != jcategories);
+  for (size_t i = 0; i<num_categories; i++)
+  {
+    GNUNET_assert (0 ==
+                   json_array_append_new (jcategories,
+                                          json_integer (categories[i])));
+  }
+  GNUNET_free (categories);
+
   {
     MHD_RESULT ret;
 
@@ -72,12 +88,16 @@ TMH_private_get_products_ID (const struct TMH_RequestHandler *rh,
                                      pd.description_i18n),
       GNUNET_JSON_pack_string ("unit",
                                pd.unit),
+      GNUNET_JSON_pack_array_steal ("categories",
+                                    jcategories),
       TALER_JSON_pack_amount ("price",
                               &pd.price),
-      GNUNET_JSON_pack_string ("image",
-                               pd.image),
-      GNUNET_JSON_pack_array_steal ("taxes",
-                                    pd.taxes),
+      GNUNET_JSON_pack_allow_null (
+        GNUNET_JSON_pack_string ("image",
+                                 pd.image)),
+      GNUNET_JSON_pack_allow_null (
+        GNUNET_JSON_pack_array_steal ("taxes",
+                                      pd.taxes)),
       GNUNET_JSON_pack_int64 ("total_stock",
                               (INT64_MAX == pd.total_stock)
                               ? -1LL
@@ -86,8 +106,9 @@ TMH_private_get_products_ID (const struct TMH_RequestHandler *rh,
                                pd.total_sold),
       GNUNET_JSON_pack_uint64 ("total_lost",
                                pd.total_lost),
-      GNUNET_JSON_pack_object_steal ("address",
-                                     pd.address),
+      GNUNET_JSON_pack_allow_null (
+        GNUNET_JSON_pack_object_steal ("address",
+                                       pd.address)),
       GNUNET_JSON_pack_allow_null (
         GNUNET_JSON_pack_timestamp ("next_restock",
                                     (pd.next_restock))),
diff --git a/src/backend/taler-merchant-httpd_private-patch-categories-ID.c b/src/backend/taler-merchant-httpd_private-patch-categories-ID.c
new file mode 100644
index 00000000..1aa489cf
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_private-patch-categories-ID.c
@@ -0,0 +1,120 @@
+/*
+  This file is part of TALER
+  (C) 2024 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as
+  published by the Free Software Foundation; either version 3,
+  or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public
+  License along with TALER; see the file COPYING.  If not,
+  see <http://www.gnu.org/licenses/>
+*/
+
+/**
+ * @file taler-merchant-httpd_private-patch-categories-ID.c
+ * @brief implementing PATCH /categories/$ID request handling
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "taler-merchant-httpd_private-patch-categories-ID.h"
+#include "taler-merchant-httpd_helper.h"
+#include <taler/taler_json_lib.h>
+
+
+MHD_RESULT
+TMH_private_patch_categories_ID (const struct TMH_RequestHandler *rh,
+                                 struct MHD_Connection *connection,
+                                 struct TMH_HandlerContext *hc)
+{
+  struct TMH_MerchantInstance *mi = hc->instance;
+  unsigned long long cnum;
+  char dummy;
+  const char *category_name;
+  const json_t *category_name_i18n;
+  struct GNUNET_JSON_Specification spec[] = {
+    GNUNET_JSON_spec_string ("name",
+                             &category_name),
+    GNUNET_JSON_spec_object_const ("name_i18n",
+                                   &category_name_i18n),
+    GNUNET_JSON_spec_end ()
+  };
+  enum GNUNET_DB_QueryStatus qs;
+
+  GNUNET_assert (NULL != mi);
+  GNUNET_assert (NULL != hc->infix);
+  if (1 != sscanf (hc->infix,
+                   "%llu%c",
+                   &cnum,
+                   &dummy))
+  {
+    GNUNET_break_op (0);
+    return TALER_MHD_reply_with_error (connection,
+                                       MHD_HTTP_BAD_REQUEST,
+                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                       "category_id must be a number");
+  }
+
+  {
+    enum GNUNET_GenericReturnValue res;
+
+    res = TALER_MHD_parse_json_data (connection,
+                                     hc->request_body,
+                                     spec);
+    if (GNUNET_OK != res)
+      return (GNUNET_NO == res)
+             ? MHD_YES
+             : MHD_NO;
+  }
+
+  qs = TMH_db->update_category (TMH_db->cls,
+                                mi->settings.id,
+                                cnum,
+                                category_name,
+                                category_name_i18n);
+  {
+    MHD_RESULT ret = MHD_NO;
+
+    switch (qs)
+    {
+    case GNUNET_DB_STATUS_HARD_ERROR:
+      GNUNET_break (0);
+      ret = TALER_MHD_reply_with_error (connection,
+                                        MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                        TALER_EC_GENERIC_DB_STORE_FAILED,
+                                        "update_category");
+      break;
+    case GNUNET_DB_STATUS_SOFT_ERROR:
+      GNUNET_break (0);
+      ret = TALER_MHD_reply_with_error (connection,
+                                        MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                        TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
+                                        "unexpected serialization problem");
+      break;
+    case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
+      ret = TALER_MHD_reply_with_error (connection,
+                                        MHD_HTTP_NOT_FOUND,
+                                        TALER_EC_MERCHANT_GENERIC_CATEGORY_UNKNOWN,
+                                        category_name);
+      break;
+    case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
+      ret = TALER_MHD_reply_static (connection,
+                                    MHD_HTTP_NO_CONTENT,
+                                    NULL,
+                                    NULL,
+                                    0);
+      break;
+    }
+    GNUNET_JSON_parse_free (spec);
+    return ret;
+  }
+}
+
+
+/* end of taler-merchant-httpd_private-patch-categories-ID.c */
diff --git a/src/backend/taler-merchant-httpd_private-patch-categories-ID.h b/src/backend/taler-merchant-httpd_private-patch-categories-ID.h
new file mode 100644
index 00000000..c88290a8
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_private-patch-categories-ID.h
@@ -0,0 +1,45 @@
+/*
+  This file is part of TALER
+  (C) 2024 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as
+  published by the Free Software Foundation; either version 3,
+  or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public
+  License along with TALER; see the file COPYING.  If not,
+  see <http://www.gnu.org/licenses/>
+*/
+
+/**
+ * @file taler-merchant-httpd_private-patch-categories-ID.h
+ * @brief implementing PATCH /private/categories/$ID request handling
+ * @author Christian Grothoff
+ */
+#ifndef TALER_MERCHANT_HTTPD_PRIVATE_PATCH_CATEGORIES_ID_H
+#define TALER_MERCHANT_HTTPD_PRIVATE_PATCH_CATEGORIES_ID_H
+
+#include "taler-merchant-httpd.h"
+
+
+/**
+ * PATCH descriptions of an existing product category.
+ *
+ * @param rh context of the handler
+ * @param connection the MHD connection to handle
+ * @param[in,out] hc context with further information about the request
+ * @return MHD result code
+ */
+MHD_RESULT
+TMH_private_patch_categories_ID (
+  const struct TMH_RequestHandler *rh,
+  struct MHD_Connection *connection,
+  struct TMH_HandlerContext *hc);
+
+#endif
diff --git a/src/backend/taler-merchant-httpd_private-patch-instances-ID.c b/src/backend/taler-merchant-httpd_private-patch-instances-ID.c
index 027d5869..70df009e 100644
--- a/src/backend/taler-merchant-httpd_private-patch-instances-ID.c
+++ b/src/backend/taler-merchant-httpd_private-patch-instances-ID.c
@@ -64,17 +64,12 @@ patch_instances_ID (struct TMH_MerchantInstance *mi,
 {
   struct TALER_MERCHANTDB_InstanceSettings is;
   const char *name;
-  const char *uts = "business";
   struct TMH_WireMethod *wm_head = NULL;
   struct TMH_WireMethod *wm_tail = NULL;
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_string ("name",
                              &name),
     GNUNET_JSON_spec_mark_optional (
-      GNUNET_JSON_spec_string ("user_type",
-                               &uts),
-      NULL),
-    GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_string ("website",
                                (const char **) &is.website),
       NULL),
@@ -115,19 +110,6 @@ patch_instances_ID (struct TMH_MerchantInstance *mi,
              ? MHD_YES
              : MHD_NO;
   }
-  if (NULL == uts)
-    uts = "business";
-  if (GNUNET_OK !=
-      TALER_KYCLOGIC_kyc_user_type_from_string (uts,
-                                                &is.ut))
-  {
-    GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "user_type");
-  }
   if (! TMH_location_object_valid (is.address))
   {
     GNUNET_break_op (0);
@@ -185,7 +167,6 @@ patch_instances_ID (struct TMH_MerchantInstance *mi,
     /* Check for equality of settings */
     if (! ( (0 == strcmp (mi->settings.name,
                           name)) &&
-            (mi->settings.ut == is.ut) &&
             ((mi->settings.email == is.email) ||
              (NULL != is.email && NULL != mi->settings.email &&
               0 == strcmp (mi->settings.email,
@@ -240,7 +221,6 @@ giveup:
   json_decref (mi->settings.jurisdiction);
   is.id = mi->settings.id;
   mi->settings = is;
-  // mi->settings.user_type = (enum TALER_KYCLOGIC_KycUserType) is.user_type;
   mi->settings.address = json_incref (mi->settings.address);
   mi->settings.jurisdiction = json_incref (mi->settings.jurisdiction);
   mi->settings.name = GNUNET_strdup (name);
diff --git a/src/backend/taler-merchant-httpd_private-patch-products-ID.c b/src/backend/taler-merchant-httpd_private-patch-products-ID.c
index 7bc327cd..6e50cced 100644
--- a/src/backend/taler-merchant-httpd_private-patch-products-ID.c
+++ b/src/backend/taler-merchant-httpd_private-patch-products-ID.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  (C) 2020 Taler Systems SA
+  (C) 2020-2024 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify
   it under the terms of the GNU Affero General Public License as
@@ -29,76 +29,6 @@
 
 
 /**
- * How often do we retry the simple INSERT database transaction?
- */
-#define MAX_RETRIES 3
-
-
-/**
- * Determine the cause of the PATCH failure in more detail and report.
- *
- * @param connection connection to report on
- * @param instance_id instance we are processing
- * @param product_id ID of the product to patch
- * @param pd product details we failed to set
- */
-static MHD_RESULT
-determine_cause (struct MHD_Connection *connection,
-                 const char *instance_id,
-                 const char *product_id,
-                 const struct TALER_MERCHANTDB_ProductDetails *pd)
-{
-  struct TALER_MERCHANTDB_ProductDetails pdx;
-  enum GNUNET_DB_QueryStatus qs;
-
-  qs = TMH_db->lookup_product (TMH_db->cls,
-                               instance_id,
-                               product_id,
-                               &pdx);
-  switch (qs)
-  {
-  case GNUNET_DB_STATUS_HARD_ERROR:
-    GNUNET_break (0);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                       TALER_EC_GENERIC_DB_FETCH_FAILED,
-                                       NULL);
-  case GNUNET_DB_STATUS_SOFT_ERROR:
-    GNUNET_break (0);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                       TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
-                                       "unexpected serialization problem");
-  case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_NOT_FOUND,
-                                       TALER_EC_MERCHANT_GENERIC_PRODUCT_UNKNOWN,
-                                       product_id);
-  case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
-    break; /* do below */
-  }
-
-  {
-    enum TALER_ErrorCode ec;
-
-    ec = TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE;
-    if (pdx.total_lost > pd->total_lost)
-      ec = TALER_EC_MERCHANT_PRIVATE_PATCH_PRODUCTS_TOTAL_LOST_REDUCED;
-    if (pdx.total_sold > pd->total_sold)
-      ec = TALER_EC_MERCHANT_PRIVATE_PATCH_PRODUCTS_TOTAL_SOLD_REDUCED;
-    if (pdx.total_stock > pd->total_stock)
-      ec = TALER_EC_MERCHANT_PRIVATE_PATCH_PRODUCTS_TOTAL_STOCKED_REDUCED;
-    TALER_MERCHANTDB_product_details_free (&pdx);
-    GNUNET_break (TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE != ec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_CONFLICT,
-                                       ec,
-                                       NULL);
-  }
-}
-
-
-/**
  * PATCH configuration of an existing instance, given its configuration.
  *
  * @param rh context of the handler
@@ -107,13 +37,15 @@ determine_cause (struct MHD_Connection *connection,
  * @return MHD result code
  */
 MHD_RESULT
-TMH_private_patch_products_ID (const struct TMH_RequestHandler *rh,
-                               struct MHD_Connection *connection,
-                               struct TMH_HandlerContext *hc)
+TMH_private_patch_products_ID (
+  const struct TMH_RequestHandler *rh,
+  struct MHD_Connection *connection,
+  struct TMH_HandlerContext *hc)
 {
   struct TMH_MerchantInstance *mi = hc->instance;
   const char *product_id = hc->infix;
   struct TALER_MERCHANTDB_ProductDetails pd = {0};
+  const json_t *categories = NULL;
   int64_t total_stock;
   enum GNUNET_DB_QueryStatus qs;
   struct GNUNET_JSON_Specification spec[] = {
@@ -135,6 +67,10 @@ TMH_private_patch_products_ID (const struct TMH_RequestHandler *rh,
       GNUNET_JSON_spec_json ("taxes",
                              &pd.taxes),
       NULL),
+    GNUNET_JSON_spec_mark_optional (
+      GNUNET_JSON_spec_array_const ("categories",
+                                    &categories),
+      NULL),
     GNUNET_JSON_spec_int64 ("total_stock",
                             &total_stock),
     GNUNET_JSON_spec_mark_optional (
@@ -155,6 +91,15 @@ TMH_private_patch_products_ID (const struct TMH_RequestHandler *rh,
       NULL),
     GNUNET_JSON_spec_end ()
   };
+  MHD_RESULT ret;
+  size_t num_cats = 0;
+  uint64_t *cats = NULL;
+  bool no_instance;
+  ssize_t no_cat;
+  bool no_product;
+  bool lost_reduced;
+  bool sold_reduced;
+  bool stock_reduced;
 
   pd.total_sold = 0; /* will be ignored anyway */
   GNUNET_assert (NULL != mi);
@@ -173,11 +118,11 @@ TMH_private_patch_products_ID (const struct TMH_RequestHandler *rh,
   if (total_stock < -1)
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "total_stock");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "total_stock");
+    goto cleanup;
   }
   if (-1 == total_stock)
     pd.total_stock = INT64_MAX;
@@ -189,23 +134,45 @@ TMH_private_patch_products_ID (const struct TMH_RequestHandler *rh,
   if (! TMH_location_object_valid (pd.address))
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "address");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "address");
+    goto cleanup;
+  }
+  num_cats = json_array_size (categories);
+  cats = GNUNET_new_array (num_cats,
+                           uint64_t);
+  {
+    size_t idx;
+    json_t *val;
+
+    json_array_foreach (categories, idx, val)
+    {
+      if (! json_is_integer (val))
+      {
+        GNUNET_break_op (0);
+        ret = TALER_MHD_reply_with_error (connection,
+                                          MHD_HTTP_BAD_REQUEST,
+                                          TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                          "categories");
+        goto cleanup;
+      }
+      cats[idx] = json_integer_value (val);
+    }
   }
+
   if (NULL == pd.description_i18n)
     pd.description_i18n = json_object ();
 
   if (! TALER_JSON_check_i18n (pd.description_i18n))
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "description_i18n");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "description_i18n");
+    goto cleanup;
   }
 
   if (NULL == pd.taxes)
@@ -214,74 +181,143 @@ TMH_private_patch_products_ID (const struct TMH_RequestHandler *rh,
   if (! TMH_taxes_array_valid (pd.taxes))
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "taxes");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "taxes");
+    goto cleanup;
   }
+
   if (NULL == pd.image)
     pd.image = "";
   if (! TMH_image_data_url_valid (pd.image))
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "image");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "image");
+    goto cleanup;
   }
+
   if ( (pd.total_stock < pd.total_sold + pd.total_lost) ||
        (pd.total_sold + pd.total_lost < pd.total_sold) /* integer overflow */)
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (
+    ret = TALER_MHD_reply_with_error (
       connection,
       MHD_HTTP_BAD_REQUEST,
       TALER_EC_MERCHANT_PRIVATE_PATCH_PRODUCTS_TOTAL_LOST_EXCEEDS_STOCKS,
       NULL);
+    goto cleanup;
   }
+
   qs = TMH_db->update_product (TMH_db->cls,
                                mi->settings.id,
                                product_id,
-                               &pd);
+                               &pd,
+                               num_cats,
+                               cats,
+                               &no_instance,
+                               &no_cat,
+                               &no_product,
+                               &lost_reduced,
+                               &sold_reduced,
+                               &stock_reduced);
+  switch (qs)
   {
-    MHD_RESULT ret = MHD_NO;
+  case GNUNET_DB_STATUS_HARD_ERROR:
+    GNUNET_break (0);
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                      TALER_EC_GENERIC_DB_STORE_FAILED,
+                                      NULL);
+    goto cleanup;
+  case GNUNET_DB_STATUS_SOFT_ERROR:
+    GNUNET_break (0);
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                      TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
+                                      "unexpected serialization problem");
+    goto cleanup;
+  case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
+    GNUNET_break (0);
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                      TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
+                                      "unexpected problem in stored procedure");
+    goto cleanup;
+  case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
+    break;
+  }
 
-    switch (qs)
-    {
-    case GNUNET_DB_STATUS_HARD_ERROR:
-      GNUNET_break (0);
-      ret = TALER_MHD_reply_with_error (connection,
-                                        MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                        TALER_EC_GENERIC_DB_STORE_FAILED,
-                                        NULL);
-      break;
-    case GNUNET_DB_STATUS_SOFT_ERROR:
-      GNUNET_break (0);
-      ret = TALER_MHD_reply_with_error (connection,
-                                        MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                        TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
-                                        "unexpected serialization problem");
-      break;
-    case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
-      ret = determine_cause (connection,
-                             mi->settings.id,
-                             product_id,
-                             &pd);
-      break;
-    case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
-      ret = TALER_MHD_reply_static (connection,
-                                    MHD_HTTP_NO_CONTENT,
-                                    NULL,
-                                    NULL,
-                                    0);
-      break;
-    }
-    GNUNET_JSON_parse_free (spec);
-    return ret;
+  if (no_instance)
+  {
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_NOT_FOUND,
+                                      TALER_EC_MERCHANT_GENERIC_INSTANCE_UNKNOWN,
+                                      mi->settings.id);
+    goto cleanup;
+  }
+  if (-1 != no_cat)
+  {
+    char cats[24];
+
+    GNUNET_snprintf (cats,
+                     sizeof (cats),
+                     "%llu",
+                     (unsigned long long) no_cat);
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_NOT_FOUND,
+                                      TALER_EC_MERCHANT_GENERIC_CATEGORY_UNKNOWN,
+                                      cats);
+    goto cleanup;
+  }
+  if (no_product)
+  {
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_NOT_FOUND,
+                                      TALER_EC_MERCHANT_GENERIC_PRODUCT_UNKNOWN,
+                                      product_id);
+    goto cleanup;
+  }
+  if (lost_reduced)
+  {
+    ret = TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_CONFLICT,
+      TALER_EC_MERCHANT_PRIVATE_PATCH_PRODUCTS_TOTAL_LOST_REDUCED,
+      NULL);
+    goto cleanup;
+  }
+  if (sold_reduced)
+  {
+    ret = TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_CONFLICT,
+      TALER_EC_MERCHANT_PRIVATE_PATCH_PRODUCTS_TOTAL_SOLD_REDUCED,
+      NULL);
+    goto cleanup;
+  }
+  if (stock_reduced)
+  {
+    ret = TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_CONFLICT,
+      TALER_EC_MERCHANT_PRIVATE_PATCH_PRODUCTS_TOTAL_STOCKED_REDUCED,
+      NULL);
+    goto cleanup;
   }
+  /* success! */
+  ret = TALER_MHD_reply_static (connection,
+                                MHD_HTTP_NO_CONTENT,
+                                NULL,
+                                NULL,
+                                0);
+cleanup:
+  GNUNET_free (cats);
+  GNUNET_JSON_parse_free (spec);
+  return ret;
 }
 
 
diff --git a/src/backend/taler-merchant-httpd_private-post-categories.c b/src/backend/taler-merchant-httpd_private-post-categories.c
new file mode 100644
index 00000000..675de765
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_private-post-categories.c
@@ -0,0 +1,170 @@
+/*
+  This file is part of TALER
+  (C) 2024 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as
+  published by the Free Software Foundation; either version 3,
+  or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public
+  License along with TALER; see the file COPYING.  If not,
+  see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file taler-merchant-httpd_private-post-categories.c
+ * @brief implementing POST /private/categories request handling
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "taler-merchant-httpd_private-post-categories.h"
+#include "taler-merchant-httpd_helper.h"
+#include <taler/taler_json_lib.h>
+
+
+/**
+ * How often do we retry the simple INSERT database transaction?
+ */
+#define MAX_RETRIES 3
+
+
+MHD_RESULT
+TMH_private_post_categories (const struct TMH_RequestHandler *rh,
+                             struct MHD_Connection *connection,
+                             struct TMH_HandlerContext *hc)
+{
+  struct TMH_MerchantInstance *mi = hc->instance;
+  const char *category_name;
+  const json_t *category_name_i18n;
+  uint64_t category_id;
+  struct GNUNET_JSON_Specification spec[] = {
+    GNUNET_JSON_spec_string ("name",
+                             &category_name),
+    GNUNET_JSON_spec_object_const ("name_i18n",
+                                   &category_name_i18n),
+    GNUNET_JSON_spec_end ()
+  };
+  enum GNUNET_DB_QueryStatus qs;
+
+  GNUNET_assert (NULL != mi);
+  {
+    enum GNUNET_GenericReturnValue res;
+
+    res = TALER_MHD_parse_json_data (connection,
+                                     hc->request_body,
+                                     spec);
+    if (GNUNET_OK != res)
+    {
+      GNUNET_break_op (0);
+      return (GNUNET_NO == res)
+             ? MHD_YES
+             : MHD_NO;
+    }
+  }
+
+  /* finally, interact with DB until no serialization error */
+  for (unsigned int i = 0; i<MAX_RETRIES; i++)
+  {
+    json_t *xcategory_name_i18n;
+
+    if (GNUNET_OK !=
+        TMH_db->start (TMH_db->cls,
+                       "POST /categories"))
+    {
+      GNUNET_break (0);
+      GNUNET_JSON_parse_free (spec);
+      return TALER_MHD_reply_with_error (connection,
+                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                         TALER_EC_GENERIC_DB_START_FAILED,
+                                         NULL);
+    }
+    qs = TMH_db->select_category_by_name (TMH_db->cls,
+                                          mi->settings.id,
+                                          category_name,
+                                          &xcategory_name_i18n,
+                                          &category_id);
+    switch (qs)
+    {
+    case GNUNET_DB_STATUS_HARD_ERROR:
+      /* Clean up and fail hard */
+      GNUNET_break (0);
+      TMH_db->rollback (TMH_db->cls);
+      GNUNET_JSON_parse_free (spec);
+      return TALER_MHD_reply_with_error (connection,
+                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                         TALER_EC_GENERIC_DB_FETCH_FAILED,
+                                         NULL);
+    case GNUNET_DB_STATUS_SOFT_ERROR:
+      /* restart transaction */
+      goto retry;
+    case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
+      /* Good, we can proceed! */
+      break;
+    case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
+      /* idempotency check: is etp == tp? */
+      {
+        bool eq;
+
+        eq = (1 == json_equal (xcategory_name_i18n,
+                               category_name_i18n));
+        json_decref (xcategory_name_i18n);
+        TMH_db->rollback (TMH_db->cls);
+        GNUNET_JSON_parse_free (spec);
+        return eq
+          ? TALER_MHD_REPLY_JSON_PACK (connection,
+                                       MHD_HTTP_OK,
+                                       GNUNET_JSON_pack_uint64 ("category_id",
+                                                                category_id))
+          : TALER_MHD_reply_with_error (connection,
+                                        MHD_HTTP_CONFLICT,
+                                        TALER_EC_MERCHANT_PRIVATE_POST_CATEGORIES_CONFLICT_CATEGORY_EXISTS,
+                                        category_name);
+      }
+    } /* end switch (qs) */
+
+    qs = TMH_db->insert_category (TMH_db->cls,
+                                  mi->settings.id,
+                                  category_name,
+                                  category_name_i18n,
+                                  &category_id);
+    if (GNUNET_DB_STATUS_HARD_ERROR == qs)
+    {
+      TMH_db->rollback (TMH_db->cls);
+      break;
+    }
+    if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs)
+    {
+      qs = TMH_db->commit (TMH_db->cls);
+      if (GNUNET_DB_STATUS_SOFT_ERROR != qs)
+        break;
+    }
+retry:
+    GNUNET_assert (GNUNET_DB_STATUS_SOFT_ERROR == qs);
+    TMH_db->rollback (TMH_db->cls);
+  } /* for RETRIES loop */
+  GNUNET_JSON_parse_free (spec);
+  if (qs < 0)
+  {
+    GNUNET_break (0);
+    return TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_INTERNAL_SERVER_ERROR,
+      (GNUNET_DB_STATUS_SOFT_ERROR == qs)
+      ? TALER_EC_GENERIC_DB_SOFT_FAILURE
+      : TALER_EC_GENERIC_DB_COMMIT_FAILED,
+      NULL);
+  }
+  return TALER_MHD_REPLY_JSON_PACK (
+    connection,
+    MHD_HTTP_OK,
+    GNUNET_JSON_pack_uint64 ("category_id",
+                             category_id));
+}
+
+
+/* end of taler-merchant-httpd_private-post-categories.c */
diff --git a/src/backend/taler-merchant-httpd_private-post-categories.h b/src/backend/taler-merchant-httpd_private-post-categories.h
new file mode 100644
index 00000000..a8431059
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_private-post-categories.h
@@ -0,0 +1,45 @@
+/*
+  This file is part of TALER
+  (C) 2024 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as
+  published by the Free Software Foundation; either version 3,
+  or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public
+  License along with TALER; see the file COPYING.  If not,
+  see <http://www.gnu.org/licenses/>
+*/
+
+/**
+ * @file taler-merchant-httpd_private-post-categories.h
+ * @brief implementing POST /categories request handling
+ * @author Christian Grothoff
+ */
+#ifndef TALER_MERCHANT_HTTPD_PRIVATE_POST_CATEGORIES_H
+#define TALER_MERCHANT_HTTPD_PRIVATE_POST_CATEGORIES_H
+
+#include "taler-merchant-httpd.h"
+
+
+/**
+ * Generate a product category.
+ *
+ * @param rh context of the handler
+ * @param connection the MHD connection to handle
+ * @param[in,out] hc context with further information about the request
+ * @return MHD result code
+ */
+MHD_RESULT
+TMH_private_post_categories (
+  const struct TMH_RequestHandler *rh,
+  struct MHD_Connection *connection,
+  struct TMH_HandlerContext *hc);
+
+#endif
diff --git a/src/backend/taler-merchant-httpd_private-post-instances.c b/src/backend/taler-merchant-httpd_private-post-instances.c
index a4cf884d..f56e7098 100644
--- a/src/backend/taler-merchant-httpd_private-post-instances.c
+++ b/src/backend/taler-merchant-httpd_private-post-instances.c
@@ -103,20 +103,6 @@ TMH_private_post_instances (const struct TMH_RequestHandler *rh,
              ? MHD_YES
              : MHD_NO;
   }
-  if (NULL == uts)
-    uts = "business";
-  if (GNUNET_OK !=
-      TALER_KYCLOGIC_kyc_user_type_from_string (uts,
-                                                &is.ut))
-  {
-    GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "user_type");
-  }
-
   {
     enum GNUNET_GenericReturnValue ret;
 
diff --git a/src/backend/taler-merchant-httpd_private-post-orders.c b/src/backend/taler-merchant-httpd_private-post-orders.c
index e8332c70..a2e3b493 100644
--- a/src/backend/taler-merchant-httpd_private-post-orders.c
+++ b/src/backend/taler-merchant-httpd_private-post-orders.c
@@ -960,6 +960,8 @@ execute_order (struct OrderContext *oc)
     struct TALER_MERCHANTDB_ProductDetails pd;
     MHD_RESULT ret;
     const struct InventoryProduct *ip;
+    size_t num_categories = 0;
+    uint64_t *categories = NULL;
 
     ip = &oc->parse_request.inventory_products[
       oc->execute_order.out_of_stock_index];
@@ -970,10 +972,13 @@ execute_order (struct OrderContext *oc)
       TMH_db->cls,
       oc->hc->instance->settings.id,
       ip->product_id,
-      &pd);
+      &pd,
+      &num_categories,
+      &categories);
     switch (qs)
     {
     case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
+      GNUNET_free (categories);
       GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                   "Order creation failed: product out of stock\n");
       ret = TALER_MHD_REPLY_JSON_PACK (
@@ -1337,6 +1342,7 @@ get_exchange_keys (void *cls,
                                         rx);
 }
 
+
 /**
  * Get rounded time interval. @a start is calculated by rounding
  * @a ts down to the nearest multiple of @a precision. @a end is
@@ -1449,9 +1455,7 @@ set_token_family (struct OrderContext *oc,
   struct TALER_MERCHANTDB_TokenFamilyKeyDetails key_details;
   struct TALER_MerchantContractTokenFamily *family = NULL;
   enum GNUNET_DB_QueryStatus qs;
-  // TODO: make this configurable. This is the granularity of token
-  //       expiration dates. This should be stored in the
-  //       database along the token family.
+  /* TODO: Implement rounding duration of token family and use this here. */
   struct GNUNET_TIME_Relative precision = GNUNET_TIME_UNIT_MONTHS;
   struct GNUNET_TIME_Timestamp min_valid_after;
   struct GNUNET_TIME_Timestamp max_valid_after;
@@ -1694,6 +1698,7 @@ set_token_family (struct OrderContext *oc,
   return GNUNET_OK;
 }
 
+
 /**
  * Serialize order into @a oc->serialize_order.contract,
  * ready to be stored in the database. Upon success, continue
@@ -1712,16 +1717,16 @@ serialize_order (struct OrderContext *oc)
 
   merchant = GNUNET_JSON_PACK (
     GNUNET_JSON_pack_string ("name",
-                              settings->name),
+                             settings->name),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_string ("website",
-                                settings->website)),
+                               settings->website)),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_string ("email",
-                                settings->email)),
+                               settings->email)),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_string ("logo",
-                                settings->logo)));
+                               settings->logo)));
   GNUNET_assert (NULL != merchant);
   {
     json_t *loca;
@@ -1733,7 +1738,7 @@ serialize_order (struct OrderContext *oc)
       loca = json_deep_copy (loca);
       GNUNET_assert (NULL != loca);
       GNUNET_assert (0 ==
-                      json_object_set_new (merchant,
+                     json_object_set_new (merchant,
                                           "address",
                                           loca));
     }
@@ -1748,7 +1753,7 @@ serialize_order (struct OrderContext *oc)
       juri = json_deep_copy (juri);
       GNUNET_assert (NULL != juri);
       GNUNET_assert (0 ==
-                      json_object_set_new (merchant,
+                     json_object_set_new (merchant,
                                           "jurisdiction",
                                           juri));
     }
@@ -1855,10 +1860,10 @@ serialize_order (struct OrderContext *oc)
 
     json_t *jchoice = GNUNET_JSON_PACK (
       GNUNET_JSON_pack_array_incref ("inputs",
-                                      inputs),
+                                     inputs),
       GNUNET_JSON_pack_array_incref ("outputs",
-                                      outputs)
-    );
+                                     outputs)
+      );
 
     GNUNET_assert (0 == json_array_append (choices, jchoice));
   }
@@ -1879,7 +1884,8 @@ serialize_order (struct OrderContext *oc)
                                oc->parse_order.fulfillment_message)),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_object_incref ("fulfillment_message_i18n",
-                                      oc->parse_order.fulfillment_message_i18n)),
+                                      oc->parse_order.fulfillment_message_i18n))
+    ,
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_string ("fulfillment_url",
                                oc->parse_order.fulfillment_url)),
@@ -1961,6 +1967,7 @@ serialize_order (struct OrderContext *oc)
   oc->phase++;
 }
 
+
 /**
  * Set max_fee in @a oc based on STEFAN value if
  * not yet present. Upon success, continue
@@ -1996,6 +2003,7 @@ set_max_fee (struct OrderContext *oc)
   oc->phase++;
 }
 
+
 /**
  * Set list of acceptable exchanges in @a oc. Upon success, continue
  * processing with set_max_fee().
@@ -2119,7 +2127,7 @@ parse_order (struct OrderContext *oc)
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_array_const ("choices",
-                                   &oc->parse_order.choices),
+                                    &oc->parse_order.choices),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       TALER_JSON_spec_web_url ("merchant_base_url",
@@ -2185,7 +2193,7 @@ parse_order (struct OrderContext *oc)
                      ret);
     return;
   }
-  if (NULL == version || 0 == strcmp("0", version))
+  if (NULL == version || 0 == strcmp ("0", version))
   {
     oc->parse_order.version = TALER_MCV_V0;
 
@@ -2200,11 +2208,11 @@ parse_order (struct OrderContext *oc)
       return;
     }
   }
-  else if (0 == strcmp("1", version))
+  else if (0 == strcmp ("1", version))
   {
     oc->parse_order.version = TALER_MCV_V1;
 
-    if (! json_is_array(oc->parse_order.choices))
+    if (! json_is_array (oc->parse_order.choices))
     {
       GNUNET_break_op (0);
       GNUNET_JSON_parse_free (spec);
@@ -2237,9 +2245,9 @@ parse_order (struct OrderContext *oc)
     return;
   }
   if ( (! no_fee) &&
-      (GNUNET_OK !=
-       TALER_amount_cmp_currency (&oc->parse_order.brutto,
-                                  &oc->parse_order.max_fee)) )
+       (GNUNET_OK !=
+        TALER_amount_cmp_currency (&oc->parse_order.brutto,
+                                   &oc->parse_order.max_fee)) )
   {
     GNUNET_break_op (0);
     GNUNET_JSON_parse_free (spec);
@@ -2516,6 +2524,7 @@ parse_order (struct OrderContext *oc)
   oc->phase++;
 }
 
+
 /**
  * Parse contract choices. Upon success, continue
  * processing with merge_inventory().
@@ -2606,7 +2615,7 @@ parse_choices (struct OrderContext *oc)
             GNUNET_JSON_spec_uint32 ("count",
                                      &input.details.token.count),
             NULL),
-          GNUNET_JSON_spec_end()
+          GNUNET_JSON_spec_end ()
         };
 
         if (GNUNET_OK !=
@@ -2665,7 +2674,8 @@ parse_choices (struct OrderContext *oc)
       size_t idx;
       json_array_foreach ((json_t *) joutputs, idx, joutput)
       {
-        struct TALER_MerchantContractOutput output = { .details.token.count = 1 };
+        struct TALER_MerchantContractOutput output = { .details.token.count = 1}
+        ;
         const char *kind;
         const char *ierror_name;
         unsigned int ierror_line;
@@ -2682,14 +2692,14 @@ parse_choices (struct OrderContext *oc)
             GNUNET_JSON_spec_uint32 ("count",
                                      &output.details.token.count),
             NULL),
-          GNUNET_JSON_spec_end()
+          GNUNET_JSON_spec_end ()
         };
 
         if (GNUNET_OK !=
             GNUNET_JSON_parse (joutput,
-                              ispec,
-                              &ierror_name,
-                              &ierror_line))
+                               ispec,
+                               &ierror_name,
+                               &ierror_line))
         {
           GNUNET_JSON_parse_free (spec);
           GNUNET_JSON_parse_free (ispec);
@@ -2744,6 +2754,7 @@ parse_choices (struct OrderContext *oc)
   oc->phase++;
 }
 
+
 /**
  * Process the @a payment_target and add the details of how the
  * order could be paid to @a order. On success, continue
@@ -2809,11 +2820,15 @@ merge_inventory (struct OrderContext *oc)
         = &oc->parse_request.inventory_products[i];
       struct TALER_MERCHANTDB_ProductDetails pd;
       enum GNUNET_DB_QueryStatus qs;
+      size_t num_categories = 0;
+      uint64_t *categories = NULL;
 
       qs = TMH_db->lookup_product (TMH_db->cls,
                                    oc->hc->instance->settings.id,
                                    ip->product_id,
-                                   &pd);
+                                   &pd,
+                                   &num_categories,
+                                   &categories);
       if (qs <= 0)
       {
         enum TALER_ErrorCode ec = TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE;
@@ -2848,6 +2863,7 @@ merge_inventory (struct OrderContext *oc)
                           ip->product_id);
         return;
       }
+      GNUNET_free (categories);
       oc->parse_order.minimum_age
         = GNUNET_MAX (oc->parse_order.minimum_age,
                       pd.minimum_age);
diff --git a/src/backend/taler-merchant-httpd_private-post-products-ID-lock.c b/src/backend/taler-merchant-httpd_private-post-products-ID-lock.c
index 184f1d28..844b2ec8 100644
--- a/src/backend/taler-merchant-httpd_private-post-products-ID-lock.c
+++ b/src/backend/taler-merchant-httpd_private-post-products-ID-lock.c
@@ -29,9 +29,10 @@
 
 
 MHD_RESULT
-TMH_private_post_products_ID_lock (const struct TMH_RequestHandler *rh,
-                                   struct MHD_Connection *connection,
-                                   struct TMH_HandlerContext *hc)
+TMH_private_post_products_ID_lock (
+  const struct TMH_RequestHandler *rh,
+  struct MHD_Connection *connection,
+  struct TMH_HandlerContext *hc)
 {
   struct TMH_MerchantInstance *mi = hc->instance;
   const char *product_id = hc->infix;
@@ -75,35 +76,48 @@ TMH_private_post_products_ID_lock (const struct TMH_RequestHandler *rh,
   switch (qs)
   {
   case GNUNET_DB_STATUS_HARD_ERROR:
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                       TALER_EC_GENERIC_DB_STORE_FAILED,
-                                       NULL);
+    return TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_INTERNAL_SERVER_ERROR,
+      TALER_EC_GENERIC_DB_STORE_FAILED,
+      NULL);
   case GNUNET_DB_STATUS_SOFT_ERROR:
     GNUNET_break (0);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                       TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
-                                       "Serialization error for single-statment request");
+    return TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_INTERNAL_SERVER_ERROR,
+      TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
+      "Serialization error for single-statment request");
   case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
-    qs = TMH_db->lookup_product (TMH_db->cls,
-                                 mi->settings.id,
-                                 product_id,
-                                 NULL);
-    if (GNUNET_DB_STATUS_HARD_ERROR == qs)
-      return TALER_MHD_reply_with_error (connection,
-                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                         TALER_EC_GENERIC_DB_STORE_FAILED,
-                                         "lookup_product");
-    if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
-      return TALER_MHD_reply_with_error (connection,
-                                         MHD_HTTP_NOT_FOUND,
-                                         TALER_EC_MERCHANT_GENERIC_PRODUCT_UNKNOWN,
-                                         product_id);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_GONE,
-                                       TALER_EC_MERCHANT_PRIVATE_POST_PRODUCTS_LOCK_INSUFFICIENT_STOCKS,
-                                       product_id);
+    {
+      size_t num_categories = 0;
+      uint64_t *categories = NULL;
+
+      qs = TMH_db->lookup_product (TMH_db->cls,
+                                   mi->settings.id,
+                                   product_id,
+                                   NULL,
+                                   &num_categories,
+                                   &categories);
+      if (GNUNET_DB_STATUS_HARD_ERROR == qs)
+        return TALER_MHD_reply_with_error (
+          connection,
+          MHD_HTTP_INTERNAL_SERVER_ERROR,
+          TALER_EC_GENERIC_DB_STORE_FAILED,
+          "lookup_product");
+      if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
+        return TALER_MHD_reply_with_error (
+          connection,
+          MHD_HTTP_NOT_FOUND,
+          TALER_EC_MERCHANT_GENERIC_PRODUCT_UNKNOWN,
+          product_id);
+      GNUNET_free (categories);
+    }
+    return TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_GONE,
+      TALER_EC_MERCHANT_PRIVATE_POST_PRODUCTS_LOCK_INSUFFICIENT_STOCKS,
+      product_id);
   case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
     return TALER_MHD_reply_static (connection,
                                    MHD_HTTP_NO_CONTENT,
diff --git a/src/backend/taler-merchant-httpd_private-post-products.c b/src/backend/taler-merchant-httpd_private-post-products.c
index 3cad91a9..3edc0c16 100644
--- a/src/backend/taler-merchant-httpd_private-post-products.c
+++ b/src/backend/taler-merchant-httpd_private-post-products.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  (C) 2020 Taler Systems SA
+  (C) 2020-2024 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify
   it under the terms of the GNU Affero General Public License as
@@ -28,50 +28,6 @@
 #include <taler/taler_json_lib.h>
 
 
-/**
- * How often do we retry the simple INSERT database transaction?
- */
-#define MAX_RETRIES 3
-
-
-/**
- * Check if the two products are identical.
- *
- * @param p1 product to compare
- * @param p2 other product to compare
- * @return true if they are 'equal', false if not or of payto_uris is not an array
- */
-static bool
-products_equal (const struct TALER_MERCHANTDB_ProductDetails *p1,
-                const struct TALER_MERCHANTDB_ProductDetails *p2)
-{
-  return ( (0 == strcmp (p1->description,
-                         p2->description)) &&
-           (1 == json_equal (p1->description_i18n,
-                             p2->description_i18n)) &&
-           (0 == strcmp (p1->unit,
-                         p2->unit)) &&
-           (GNUNET_OK ==
-            TALER_amount_cmp_currency (&p1->price,
-                                       &p2->price)) &&
-           (0 == TALER_amount_cmp (&p1->price,
-                                   &p2->price)) &&
-           (1 == json_equal (p1->taxes,
-                             p2->taxes)) &&
-           (p1->total_stock == p2->total_stock) &&
-           (p1->total_sold == p2->total_sold) &&
-           (p1->total_lost == p2->total_lost) &&
-           (p1->minimum_age == p2->minimum_age) &&
-           (0 == strcmp (p1->image,
-                         p2->image)) &&
-           (1 == json_equal (p1->address,
-                             p2->address)) &&
-           (GNUNET_TIME_timestamp_cmp (p1->next_restock,
-                                       ==,
-                                       p2->next_restock) ) );
-}
-
-
 MHD_RESULT
 TMH_private_post_products (const struct TMH_RequestHandler *rh,
                            struct MHD_Connection *connection,
@@ -79,9 +35,9 @@ TMH_private_post_products (const struct TMH_RequestHandler *rh,
 {
   struct TMH_MerchantInstance *mi = hc->instance;
   struct TALER_MERCHANTDB_ProductDetails pd = { 0 };
+  const json_t *categories = NULL;
   const char *product_id;
   int64_t total_stock;
-  enum GNUNET_DB_QueryStatus qs;
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_string ("product_id",
                              &product_id),
@@ -103,6 +59,10 @@ TMH_private_post_products (const struct TMH_RequestHandler *rh,
       GNUNET_JSON_spec_json ("taxes",
                              &pd.taxes),
       NULL),
+    GNUNET_JSON_spec_mark_optional (
+      GNUNET_JSON_spec_array_const ("categories",
+                                    &categories),
+      NULL),
     GNUNET_JSON_spec_int64 ("total_stock",
                             &total_stock),
     GNUNET_JSON_spec_mark_optional (
@@ -119,6 +79,13 @@ TMH_private_post_products (const struct TMH_RequestHandler *rh,
       NULL),
     GNUNET_JSON_spec_end ()
   };
+  size_t num_cats = 0;
+  uint64_t *cats = NULL;
+  bool conflict;
+  bool no_instance;
+  ssize_t no_cat;
+  enum GNUNET_DB_QueryStatus qs;
+  MHD_RESULT ret;
 
   GNUNET_assert (NULL != mi);
   {
@@ -138,13 +105,33 @@ TMH_private_post_products (const struct TMH_RequestHandler *rh,
   if (total_stock < -1)
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "total_stock");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "total_stock");
+    goto cleanup;
   }
+  num_cats = json_array_size (categories);
+  cats = GNUNET_new_array (num_cats,
+                           uint64_t);
+  {
+    size_t idx;
+    json_t *val;
 
+    json_array_foreach (categories, idx, val)
+    {
+      if (! json_is_integer (val))
+      {
+        GNUNET_break_op (0);
+        ret = TALER_MHD_reply_with_error (connection,
+                                          MHD_HTTP_BAD_REQUEST,
+                                          TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                          "categories");
+        goto cleanup;
+      }
+      cats[idx] = json_integer_value (val);
+    }
+  }
 
   if (-1 == total_stock)
     pd.total_stock = INT64_MAX;
@@ -162,31 +149,31 @@ TMH_private_post_products (const struct TMH_RequestHandler *rh,
   if (! TMH_taxes_array_valid (pd.taxes))
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "taxes");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "taxes");
+    goto cleanup;
   }
 
   if (! TMH_location_object_valid (pd.address))
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "address");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "address");
+    goto cleanup;
   }
 
   if (! TALER_JSON_check_i18n (pd.description_i18n))
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "description_i18n");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "description_i18n");
+    goto cleanup;
   }
 
   if (NULL == pd.image)
@@ -194,110 +181,88 @@ TMH_private_post_products (const struct TMH_RequestHandler *rh,
   if (! TMH_image_data_url_valid (pd.image))
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "image");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "image");
+    goto cleanup;
   }
 
-  /* finally, interact with DB until no serialization error */
-  for (unsigned int i = 0; i<MAX_RETRIES; i++)
+  qs = TMH_db->insert_product (TMH_db->cls,
+                               mi->settings.id,
+                               product_id,
+                               &pd,
+                               num_cats,
+                               cats,
+                               &no_instance,
+                               &conflict,
+                               &no_cat);
+  switch (qs)
   {
-    /* Test if an product of this id is known */
-    struct TALER_MERCHANTDB_ProductDetails epd;
-
-    if (GNUNET_OK !=
-        TMH_db->start (TMH_db->cls,
-                       "/post products"))
-    {
-      GNUNET_break (0);
-      GNUNET_JSON_parse_free (spec);
-      return TALER_MHD_reply_with_error (connection,
-                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                         TALER_EC_GENERIC_DB_START_FAILED,
-                                         NULL);
-    }
-    qs = TMH_db->lookup_product (TMH_db->cls,
-                                 mi->settings.id,
-                                 product_id,
-                                 &epd);
-    switch (qs)
-    {
-    case GNUNET_DB_STATUS_HARD_ERROR:
-      /* Clean up and fail hard */
-      GNUNET_break (0);
-      TMH_db->rollback (TMH_db->cls);
-      GNUNET_JSON_parse_free (spec);
-      return TALER_MHD_reply_with_error (connection,
-                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                         TALER_EC_GENERIC_DB_FETCH_FAILED,
-                                         NULL);
-    case GNUNET_DB_STATUS_SOFT_ERROR:
-      /* restart transaction */
-      goto retry;
-    case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
-      /* Good, we can proceed! */
-      break;
-    case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
-      /* idempotency check: is epd == pd? */
-      {
-        bool eq;
-
-        eq = products_equal (&pd,
-                             &epd);
-        TALER_MERCHANTDB_product_details_free (&epd);
-        TMH_db->rollback (TMH_db->cls);
-        GNUNET_JSON_parse_free (spec);
-        return eq
-          ? TALER_MHD_reply_static (connection,
-                                    MHD_HTTP_NO_CONTENT,
-                                    NULL,
-                                    NULL,
-                                    0)
-          : TALER_MHD_reply_with_error (connection,
-                                        MHD_HTTP_CONFLICT,
-                                        TALER_EC_MERCHANT_PRIVATE_POST_PRODUCTS_CONFLICT_PRODUCT_EXISTS,
-                                        product_id);
-      }
-    } /* end switch (qs) */
-
-    qs = TMH_db->insert_product (TMH_db->cls,
-                                 mi->settings.id,
-                                 product_id,
-                                 &pd);
-    if (GNUNET_DB_STATUS_HARD_ERROR == qs)
-    {
-      TMH_db->rollback (TMH_db->cls);
-      break;
-    }
-    if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs)
-    {
-      qs = TMH_db->commit (TMH_db->cls);
-      if (GNUNET_DB_STATUS_SOFT_ERROR != qs)
-        break;
-    }
-retry:
-    GNUNET_assert (GNUNET_DB_STATUS_SOFT_ERROR == qs);
-    TMH_db->rollback (TMH_db->cls);
-  } /* for RETRIES loop */
-  GNUNET_JSON_parse_free (spec);
-  if (qs < 0)
-  {
-    GNUNET_break (0);
-    return TALER_MHD_reply_with_error (
+  case GNUNET_DB_STATUS_HARD_ERROR:
+  case GNUNET_DB_STATUS_SOFT_ERROR:
+    ret = TALER_MHD_reply_with_error (
       connection,
       MHD_HTTP_INTERNAL_SERVER_ERROR,
       (GNUNET_DB_STATUS_SOFT_ERROR == qs)
       ? TALER_EC_GENERIC_DB_SOFT_FAILURE
       : TALER_EC_GENERIC_DB_COMMIT_FAILED,
       NULL);
+    goto cleanup;
+  case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
+    ret = TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_INTERNAL_SERVER_ERROR,
+      TALER_EC_GENERIC_DB_INVARIANT_FAILURE,
+      NULL);
+    goto cleanup;
+  case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
+    break;
   }
-  return TALER_MHD_reply_static (connection,
-                                 MHD_HTTP_NO_CONTENT,
-                                 NULL,
-                                 NULL,
-                                 0);
+  if (no_instance)
+  {
+    ret = TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_NOT_FOUND,
+      TALER_EC_MERCHANT_GENERIC_INSTANCE_UNKNOWN,
+      mi->settings.id);
+    goto cleanup;
+  }
+  if (conflict)
+  {
+    ret = TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_CONFLICT,
+      TALER_EC_MERCHANT_PRIVATE_POST_PRODUCTS_CONFLICT_PRODUCT_EXISTS,
+      product_id);
+    goto cleanup;
+  }
+  if (-1 != no_cat)
+  {
+    char nocats[24];
+
+    GNUNET_break_op (0);
+    TMH_db->rollback (TMH_db->cls);
+    GNUNET_snprintf (nocats,
+                     sizeof (nocats),
+                     "%llu",
+                     (unsigned long long) no_cat);
+    ret = TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_NOT_FOUND,
+      TALER_EC_MERCHANT_GENERIC_CATEGORY_UNKNOWN,
+      nocats);
+    goto cleanup;
+  }
+  ret = TALER_MHD_reply_static (connection,
+                                MHD_HTTP_NO_CONTENT,
+                                NULL,
+                                NULL,
+                                0);
+cleanup:
+  GNUNET_JSON_parse_free (spec);
+  GNUNET_free (cats);
+  return ret;
 }
 
 
diff --git a/src/backend/taler-merchant-webhook.c b/src/backend/taler-merchant-webhook.c
index 80db78fd..1d17843e 100644
--- a/src/backend/taler-merchant-webhook.c
+++ b/src/backend/taler-merchant-webhook.c
@@ -506,7 +506,7 @@ run (void *cls,
   {
     GNUNET_break (0);
     GNUNET_SCHEDULER_shutdown ();
-    global_ret = EXIT_NO_RESTART;
+    global_ret = EXIT_FAILURE;
     return;
   }
   if (NULL ==
@@ -524,7 +524,7 @@ run (void *cls,
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                 "Failed to connect to database\n");
     GNUNET_SCHEDULER_shutdown ();
-    global_ret = EXIT_NO_RESTART;
+    global_ret = EXIT_FAILURE;
     return;
   }
   {
diff --git a/src/backend/taler-merchant-wirewatch.c b/src/backend/taler-merchant-wirewatch.c
index 17eb7a0a..bba101e3 100644
--- a/src/backend/taler-merchant-wirewatch.c
+++ b/src/backend/taler-merchant-wirewatch.c
@@ -641,7 +641,7 @@ run (void *cls,
   {
     GNUNET_break (0);
     GNUNET_SCHEDULER_shutdown ();
-    global_ret = EXIT_NO_RESTART;
+    global_ret = EXIT_FAILURE;
     return;
   }
   if (NULL ==
@@ -659,7 +659,7 @@ run (void *cls,
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                 "Failed to connect to database\n");
     GNUNET_SCHEDULER_shutdown ();
-    global_ret = EXIT_NO_RESTART;
+    global_ret = EXIT_FAILURE;
     return;
   }
   {