A BPT Exception is an event thrown by a role when the work received does not match what was asked for.

It is not a defect report. A defect says the thing is broken. An exception says the thing was asked for wrongly, or understood wrongly, somewhere upstream — and that the asking is what has to be revisited.

The cascade

Exceptions travel against the flow of work, from the domain that catches the mismatch back towards the domain that caused it.

flowchart LR
    T(Technology) -->|Exception| P(Products)
    P -->|Exception| B(Business)
  1. Technology catches it first. Engineering is where a mismatch becomes undeniable: what was specified cannot be built, or what was built cannot do what was asked. The exception goes back to Products with the full account of what happened.
  2. Products reviews. Products either resolves it inside its own domain — the specification was wrong and Products owns the specification — or it cannot, and the exception continues.
  3. Business is the final arbiter. An exception that reaches Business has arrived at the top accountable domain, where the product decision originated. There is nowhere further for it to go.
IMPORTANT
An exception propagates with the full trace back: through the Products decisions, all the way to the Business decisions that started it.

Why the trace matters

Without the trace, every failure looks like a Technology failure, because Technology is where it surfaced. The organization then fixes the symptom, at the cheapest place to blame and the most expensive place to change.

With the trace, the true origin is visible — and it frequently sits outside Technology altogether: a business decision whose reasoning nobody recorded, an initiative scoped against an assumption that has since been disproven.

That is why an exception reaching Business must land on something: the Business Decision Record that holds the why. Without it the cascade ends at a decision nobody can explain, and the exercise proves nothing.

BPT Agility

Backtracking is built into the operating model rather than bolted on as escalation. That is what makes the loop agile in the only sense that matters at scale: expensive mistakes are discovered at their source, while there is still something to correct.

NOTE
An exception is an event like any other in the loop. It is exchanged through the domain interfaces and recorded in the domain repositories — not carried by email.