Fix Paystack, Integrate MPesa Rapidly

I have an active code-base that suddenly began rejecting live payments through Paystack. I need the fault isolated and patched, then I want MPesa (Daraja/Safaricom) added as a second gateway—all inside a tight 5-hour window from the moment we start a screen-share session.

Here’s what has to happen:
• Paystack: identify the exact failure point, restore successful charge flows, and confirm webhooks fire with correct status codes.
• MPesa: wire up the STK Push workflow, handle callbacks, store transaction metadata, and surface clear success / error messages in the UI.
• Testing: prove both gateways run side-by-side in sandbox and live mode, then push the working branch to my repo.

I’ll grant direct access to the repo, environment variables, and existing payment components. The project is built with a typical full-stack mix—React on the front, Node/Express and MySQL on the back—so plan on working with JavaScript, REST APIs, and whatever helper libraries you prefer.

If you can demonstrate past Paystack or MPesa integrations and are comfortable debugging quickly while on call with me, jump in; there are many more tasks in this ongoing build once these payments are stable.