Reversal

Reverse completed M-Pesa transactions by initiating a reversal request and handling asynchronous result notifications.

User Stories

• As a fintech product owner, I want to programmatically reverse M-Pesa transactions so that I can handle customer requests efficiently.
• As an integrations developer, I want a simple client and clear webhook callbacks so I can implement reliable end-to-end flows with minimal boilerplate.
• As a billing operations engineer, I want result and timeout notifications with acknowledgements so I can reconcile transactions and trigger retries or alerts when needed.
• As a reseller partner, I want a tested SDK and examples so I can onboard quickly and reduce integration defects.

Parameters Definition

Parameter	Type	Description
Initiatorrequired str	String	Name of the initiating user (must be pre-approved by Safaricom).
SecurityCredentialrequired str	String	Encrypted credential of the user (base64 encoded).
TransactionIDrequired str	String	Unique M-Pesa transaction ID to reverse.
Amountrequired float	Float	Amount to reverse (should match original transaction).
ReceiverPartyrequired int	Integer	Party receiving the reversed funds (shortcode or MSISDN).
ResultURLrequired str	String	HTTPS endpoint that will receive the result notification.
QueueTimeOutURLrequired str	String	HTTPS endpoint that will receive timeout notifications.
Remarksrequired str	String	Reason for the reversal (<= 100 characters).
Occasion str	String	Optional additional information (<= 100 characters).
OriginatorConversationID str	String	Unique identifier for the conversation (returned in response).
ConversationID str	String	Unique conversation ID assigned by M-Pesa (returned in response).
ResponseCode str	String	Status code of the reversal request (returned in response).
ResponseDescription str	String	Description of the reversal request status (returned in response).

Overview

Reversal allows you to cancel or reverse a previously completed M-Pesa transaction. It is an asynchronous operation with callbacks for results and timeouts.

💡Implementation Options

• Use the MpesaClient facade for simple and safe integration: it manages authentication, header injection and returns typed Pydantic models.
• Use the Direct API (Reversal service + TokenManager + HttpClient) if you need full control over request/response handling, middleware, or custom error behaviors.

💡Why use MpesaClient

The facade handles token retrieval and attaches Authorization headers so you can call high-level operations like initiating a reversal with minimal boilerplate.

Quick Setup

Python

# Example: initiate a reversal using the high-level client
from mpesakit import MpesaClient

client = MpesaClient(consumer_key="...", consumer_secret="...", environment="sandbox")

resp = client.reversal.reverse(
  initiator="TestInit610",
  security_credential="encrypted_credential",
  transaction_id="LKXXXX1234",
  amount=100,
  receiver_party=600610,
  result_url="https://your.example/result",
  queue_timeout_url="https://your.example/timeout",
  remarks="Wrong recipient",
  occasion="Refund"
)

if resp.is_successful():
  print("Reversal initiated successfully")
else:
  print("Reversal failed:", resp.ResponseDescription)

💡Notes

• The facade returns typed Pydantic models (e.g., ReversalResponse) for ergonomic access to fields and helpers like is_successful().
• Authentication tokens are handled transparently by the client.

Webhook Handling (Result & Timeout)

Python

# Example: simple FastAPI endpoints for Reversal Result and Timeout
from fastapi import FastAPI, Request, HTTPException
from mpesakit.reversal import ReversalResultCallback, ReversalResultCallbackResponse, ReversalTimeoutCallback, ReversalTimeoutCallbackResponse
from mpesakit.security.ip_whitelist import is_mpesa_ip_allowed

app = FastAPI()

@app.post("/reversal/result")
async def reversal_result(request: Request):
  payload = await request.json()
  caller_ip = (request.headers.get("x-forwarded-for") or request.client.host).split(",")[0].strip()
  if not is_mpesa_ip_allowed(caller_ip):
      raise HTTPException(status_code=403, detail="forbidden")

  data = ReversalResultCallback(**payload)  # will validate incoming fields
  # process the result (update database, notify user, etc.)
  ack = ReversalResultCallbackResponse()
  return ack.model_dump(mode="json")


@app.post("/reversal/timeout")
async def reversal_timeout(request: Request):
  payload = await request.json()
  caller_ip = (request.headers.get("x-forwarded-for") or request.client.host).split(",")[0].strip()
  if not is_mpesa_ip_allowed(caller_ip):
      raise HTTPException(status_code=403, detail="forbidden")

  # process timeout notification (log, retry logic, etc.)
  ack = ReversalTimeoutCallbackResponse()
  return ack.model_dump(mode="json")

💡Important behavior

• Result and timeout endpoints should return acknowledgements (ResultCode 0). This confirms receipt to Safaricom.
• Process the actual reversal result asynchronously based on the data in the result callback.

Responses & Helpers

Example Reversal Success Response

{
  "OriginatorConversationID": "71840-27539181-07",
  "ConversationID": "AG_20210709_12346c8e6f8858d7b70a",
  "ResponseCode": "0",
  "ResponseDescription": "Accept the service request successfully."
}

💡Response Handling

• ReversalResponse provides is_successful() which validates the ResponseCode for easy success checks.
• The SDK normalizes minor provider response typos (e.g., 'OriginatorCoversationID') so fields are accessible reliably.

Error Handling

Python

# Handle errors when calling the service
try:
  resp = client.reversal.reverse(...)
except Exception as exc:
  # The underlying HTTP client may raise exceptions on network errors; log and retry as appropriate
  print("Reversal failed:", exc)

💡Notes

• HTTP or network errors raised by the HttpClient bubble up; wrap calls in try/except for robust production behavior.
• Tests exercise error flows to ensure exceptions propagate when the HTTP client fails.

Testing & Expected Behaviors

• Reversal:

  • The service posts to /mpesa/reversal/v1/request with Authorization header set via TokenManager.
  • Responses are returned as ReversalResponse instances.
  • The implementation tolerates a common provider typo ("OriginatorCoversationID") and maps it to OriginatorConversationID.

• Validation:

  • Incoming payloads are validated against ReversalResultCallback and ReversalTimeoutCallback. Missing required fields or invalid formats will raise validation errors.
  • Use the provided response schemas for acknowledgements; invalid codes are rejected by the model validator.

Next Steps

💡What's Next?

• Implement robust webhook handlers for result and timeout notifications. Log and persist notifications to support reconciliation.
• Add observability and retry strategies around reversal calls and webhook processing to handle transient failures.

Related Documentation

• 📡 Webhook Setup Guide - Best practices for building reliable endpoints
• 🏗️ Production Setup - Go-live checklist, security and monitoring