knowledge-interview

Knowledge interview

Getting what isn't written down.

Why this exists

The most valuable source in a legacy organization is a person who has been there nine years. They know why the retry count is three, which customer the special case exists for, what broke in 2021, and which of the four services named payments-* actually processes payments. None of it is written down, and much of it cannot be derived from the code at any cost.

You will get forty minutes of their time, probably once.

The default failure is going in with a vague "can you walk me through the system?" and getting a forty-minute monologue that is genuinely interesting and answers none of your actual questions. The second failure is subtler: treating everything they say as fact. People misremember, describe intended rather than actual behavior, and confidently explain systems that changed underneath them two years ago.

When this applies

• Before or after meeting someone who knows a system you don't
• Repeated [unverified] gaps that only a person can close
• Handover conversations, in either direction
• Business rules with no written source
• Limited time with a busy expert

When it doesn't

• The code answers it — read the code, don't spend the person's goodwill
• You need a decision rather than knowledge — that's a different conversation
• Formal requirements gathering with a stakeholder — that's requirements-to-spec

Prerequisites

• .fde/02-system-map.md and any [unverified] gaps from other artifacts — these are your question list
• .fde/02b-ownership.md — so you're asking the right person

Procedure

1. Exhaust the code first

Never spend an expert's time on something you could have grepped. It's the fastest way to be deprioritized, and it wastes the scarcest resource in the engagement.

Go in having read the code. The questions that survive that filter are the good ones — the whys, the history, the things not written down.

Signal that you've done the work: "I traced the refund path as far as the event publish at OrderService:132 and couldn't find the consumer — is it in another service?" That question demonstrates preparation, is easy to answer, and gets you a better forty minutes than "how do refunds work?"