The anatomy of a requirement nobody wrote down
Unwritten requirements share a life cycle. Knowing it makes them findable in advance.
Requirements that go missing are not the obscure ones. They are usually the ones everyone in the room already agreed on, which is precisely why nobody wrote them down.
The life cycle
- Stated once, in conversation, by someone close to the customer
- Agreed immediately, so it generates no argument and no artefact
- Assumed thereafter, and referenced obliquely — 'obviously we handle that'
- Discovered in implementation, when it is expensive
Consensus is the risk factor
Disagreement produces documentation. Somebody writes the counter-argument down. Agreement produces nothing, so the requirements least likely to survive in writing are the ones nobody thought to defend.
Where to look
In the sentences that begin 'obviously', 'of course' and 'we'd never'. In the interview moment where the customer describes their environment rather than their need. And in whatever the last incident taught you, which is the most reliably unwritten requirement of all.
Stop writing PRDs without understanding the product.
Anchor reads your interviews, tickets and docs first — then writes, citing every line.
