We used an AI agent to add a fraud flag to a COBOL banking system (without rewriting it)

COBOL still runs a huge portion of the banking world — but making even small changes to legacy systems can be painful.

We put together a short demo showing how we enhanced a COBOL-based banking system by adding a fraud warning flag for transactions over $10,000 — without rewriting the system or breaking existing logic.

In the video, we walk through:

• Setting up a structured workflow (Zenflow environment)
• Defining clear validation tasks
• Running an AI agent to implement the change
• Reviewing and testing the results

The interesting part wasn’t just “AI writes code” — it was the structured validation and controlled execution. Instead of prompting and hoping for the best, the workflow enforces guardrails around how changes are made.

Curious what folks here think:

• Would you trust an AI-assisted workflow on legacy financial systems?
• How are you handling modernization where full rewrites aren’t realistic?
• Anyone here actively working with COBOL in production?

Happy to share the demo link if anyone’s interested.