Placeholder draft — clear and finalise before launch.

The demo went well. Almost too well. A tier-1 bank, a room full of senior stakeholders, and a prototype that answered the kind of question their teams spend hours chasing. People leaned forward. Someone said the word “transformational”. Six months later the same system was quietly switched off.

This is the story of what happened in between, and why I now believe the demo was the least important thing in the room that day.

What the demo proved — and what it didn’t

A demo proves a path is possible. It does not prove the path is operable. Those are different claims, and the gap between them is where most enterprise pilots die.

The prototype handled the happy path beautifully because we built it to. What it never had to do was survive a Monday morning: stale data, an upstream system mid-migration, a compliance reviewer who needed to see why it answered the way it did, and a support team who had never been told it existed.

The three things that were missing

When I trace back why it stalled, it always comes down to the same three gaps — the ones I now refuse to start a build without.

  1. Success criteria nobody had written down. Everyone “knew” what good looked like. No two people agreed when you asked them to write it in a sentence.
  2. No evaluation harness. We could tell the system was impressive. We could not tell whether it was better on Tuesday than it had been on Monday.
  3. No named owner. There was an enthusiastic sponsor. There was no one whose week got measurably harder when it broke — so when it broke, nothing happened.

What I’d change

Less of the demo, earlier. More of the boring scaffolding, sooner. Write the success criteria with the person paying, in the first week, before a line of the real system exists. Stand up the evaluation harness before the model is any good, so you can watch it get good. And find the owner before you find the architecture.

None of that is glamorous. All of it is what separates a pilot that survives from a demo that gets applause and then gets switched off.