diff --git a/frontend/pshared/lib/config/common.dart b/frontend/pshared/lib/config/common.dart
index c6b47267..a19eed48 100644
--- a/frontend/pshared/lib/config/common.dart
+++ b/frontend/pshared/lib/config/common.dart
@@ -2,8 +2,10 @@ import 'package:flutter/material.dart';
 
 
 class CommonConstants {
-  static String apiProto = 'https';
-  static String apiHost = 'app.sendico.io';
+  // static String apiProto = 'https';
+  // static String apiHost = 'app.sendico.io';
+  static String apiProto = 'http';
+  static String apiHost = 'localhost:3000';
   static String apiEndpoint = '/api/v1';
   static String amplitudeSecret = 'c3d75b3e2520d708440acbb16b923e79';
   static String amplitudeServerZone = 'EU';
diff --git a/frontend/pshared/lib/models/resources.dart b/frontend/pshared/lib/models/resources.dart
index e0fcd182..ead33148 100644
--- a/frontend/pshared/lib/models/resources.dart
+++ b/frontend/pshared/lib/models/resources.dart
@@ -15,6 +15,10 @@ enum ResourceType {
   @JsonValue('automations')
   automations,
 
+  /// Tracks changes made to resources
+  @JsonValue('callbacks')
+  callbacks,
+
   /// Tracks changes made to resources
   @JsonValue('changes')
   changes,
diff --git a/interface/api/payments/by_quote.yaml b/interface/api/payments/by_quote.yaml
index e779215e..9ee59cd6 100644
--- a/interface/api/payments/by_quote.yaml
+++ b/interface/api/payments/by_quote.yaml
@@ -1,7 +1,7 @@
 post:
   tags: [Payments]
   summary: Initiate payment using quote reference
-  description: Executes one payment from an existing quote reference (`quoteRef` required, `intent` forbidden).
+  description: Executes one payment from an existing quote reference.
   operationId: paymentsInitiateByQuote
   security:
     - bearerAuth: []
@@ -12,14 +12,7 @@ post:
     content:
       application/json:
         schema:
-          allOf:
-            - $ref: ./request/payment.yaml#/components/schemas/InitiatePaymentRequest
-            - type: object
-              required:
-                - quoteRef
-              not:
-                required:
-                  - intent
+          $ref: ./request/payment.yaml#/components/schemas/InitiatePaymentByQuoteRequest
   responses:
     '200':
       description: Payment initiated by quote
diff --git a/interface/api/payments/documents_act.yaml b/interface/api/payments/documents_act.yaml
new file mode 100644
index 00000000..41eefaf4
--- /dev/null
+++ b/interface/api/payments/documents_act.yaml
@@ -0,0 +1,55 @@
+get:
+  tags: [Payments]
+  summary: Download act document by payment reference
+  description: Returns the billing act document as binary content.
+  operationId: paymentsGetActDocument
+  security:
+    - bearerAuth: []
+  parameters:
+    - $ref: ../parameters/organizations_ref.yaml#/components/parameters/OrganizationsRef
+    - name: payment_ref
+      in: query
+      required: false
+      description: Payment reference for which to fetch the act document.
+      schema:
+        type: string
+    - name: paymentRef
+      in: query
+      required: false
+      description: Alias of `payment_ref`.
+      schema:
+        type: string
+  responses:
+    '200':
+      description: Act document file
+      content:
+        application/pdf:
+          schema:
+            type: string
+            format: binary
+        application/octet-stream:
+          schema:
+            type: string
+            format: binary
+    '400':
+      $ref: ../response/operation.yaml#/components/responses/BadRequest
+    '401':
+      $ref: ../response/operation.yaml#/components/responses/Unauthorized
+    '403':
+      $ref: ../response/operation.yaml#/components/responses/Forbidden
+    '404':
+      $ref: ../response/operation.yaml#/components/responses/NotFound
+    '412':
+      description: Precondition failed
+      content:
+        application/json:
+          schema:
+            $ref: ../response/response.yaml#/components/schemas/ErrorResponse
+    '500':
+      $ref: ../response/operation.yaml#/components/responses/InternalServerError
+    '503':
+      description: Upstream service unavailable
+      content:
+        application/json:
+          schema:
+            $ref: ../response/response.yaml#/components/schemas/ErrorResponse
diff --git a/interface/api/payments/list.yaml b/interface/api/payments/list.yaml
index 3a26d51d..e01a5c91 100644
--- a/interface/api/payments/list.yaml
+++ b/interface/api/payments/list.yaml
@@ -17,6 +17,12 @@ get:
       description: Filter by quotation reference used for execution.
       schema:
         type: string
+    - name: quote_ref
+      in: query
+      required: false
+      description: Alias of `quotation_ref`.
+      schema:
+        type: string
     - name: created_from
       in: query
       required: false
@@ -24,6 +30,13 @@ get:
       schema:
         type: string
         format: date-time
+    - name: createdFrom
+      in: query
+      required: false
+      description: Alias of `created_from`.
+      schema:
+        type: string
+        format: date-time
     - name: created_to
       in: query
       required: false
@@ -31,6 +44,13 @@ get:
       schema:
         type: string
         format: date-time
+    - name: createdTo
+      in: query
+      required: false
+      description: Alias of `created_to`.
+      schema:
+        type: string
+        format: date-time
     - $ref: ../parameters/state.yaml#/components/parameters/State
     - $ref: ../parameters/states.yaml#/components/parameters/States
     - $ref: ../parameters/filter_states.yaml#/components/parameters/FilterStates
diff --git a/interface/api/payments/registry.yaml b/interface/api/payments/registry.yaml
new file mode 100644
index 00000000..42d796d7
--- /dev/null
+++ b/interface/api/payments/registry.yaml
@@ -0,0 +1,30 @@
+get:
+  tags: [Payments]
+  summary: Get discovery registry snapshot for payments dependencies
+  description: Returns the latest discovery lookup payload used by payments integrations.
+  operationId: paymentsRegistryList
+  security:
+    - bearerAuth: []
+  parameters:
+    - $ref: ../parameters/organizations_ref.yaml#/components/parameters/OrganizationsRef
+  responses:
+    '200':
+      description: Discovery registry payload
+      content:
+        application/json:
+          schema:
+            allOf:
+              - $ref: ../response/response.yaml#/components/schemas/BaseResponse
+              - type: object
+                properties:
+                  data:
+                    type: object
+                    additionalProperties: true
+    '400':
+      $ref: ../response/operation.yaml#/components/responses/BadRequest
+    '401':
+      $ref: ../response/operation.yaml#/components/responses/Unauthorized
+    '403':
+      $ref: ../response/operation.yaml#/components/responses/Forbidden
+    '500':
+      $ref: ../response/operation.yaml#/components/responses/InternalServerError
diff --git a/interface/api/payments/registry_refresh.yaml b/interface/api/payments/registry_refresh.yaml
new file mode 100644
index 00000000..4719af70
--- /dev/null
+++ b/interface/api/payments/registry_refresh.yaml
@@ -0,0 +1,32 @@
+get:
+  tags: [Payments]
+  summary: Get latest discovery refresh event for payments dependencies
+  description: Returns the latest refresh event consumed by the payments API.
+  operationId: paymentsRegistryRefreshGet
+  security:
+    - bearerAuth: []
+  parameters:
+    - $ref: ../parameters/organizations_ref.yaml#/components/parameters/OrganizationsRef
+  responses:
+    '200':
+      description: Discovery refresh payload
+      content:
+        application/json:
+          schema:
+            allOf:
+              - $ref: ../response/response.yaml#/components/schemas/BaseResponse
+              - type: object
+                properties:
+                  data:
+                    type:
+                      - object
+                      - 'null'
+                    additionalProperties: true
+    '400':
+      $ref: ../response/operation.yaml#/components/responses/BadRequest
+    '401':
+      $ref: ../response/operation.yaml#/components/responses/Unauthorized
+    '403':
+      $ref: ../response/operation.yaml#/components/responses/Forbidden
+    '500':
+      $ref: ../response/operation.yaml#/components/responses/InternalServerError
diff --git a/interface/api/payments/request/payment.yaml b/interface/api/payments/request/payment.yaml
index a93eb217..ac5df516 100644
--- a/interface/api/payments/request/payment.yaml
+++ b/interface/api/payments/request/payment.yaml
@@ -120,3 +120,16 @@ components:
             quoteRef:
               description: Reference to a previously generated multi-quote.
               type: string
+
+    InitiatePaymentByQuoteRequest:
+      description: Request payload to initiate one payment from an existing quote reference.
+      allOf:
+        - $ref: ./payment.yaml#/components/schemas/PaymentBase
+        - type: object
+          additionalProperties: false
+          required:
+            - quoteRef
+          properties:
+            quoteRef:
+              description: Reference to a previously generated quote to execute.
+              type: string