Architecture diagrams for client work.

The situation

Consulting engagements start with an unfamiliar system and a short assessment window, and the deliverable is frequently a document explaining what the client has. The work is the same as onboarding except compressed and repeated across clients, so anything that shortens the first pass compounds across engagements.

The confidentiality constraint

Client code is under an NDA and running it through a hosted service is often a contract breach regardless of the vendor's security posture, because the agreement names who may process it. A desktop application running a local model keeps the code on your machine, which is a materially different position to be in when the question comes up, and it will.

Repeatable across engagements

Because the tooling is local and the process is the same each time, the first-pass diagram is a routine step rather than a bespoke effort. What varies is the analysis you layer on top, which is the part clients are paying for.

Deliverables that survive handover

Diagrams export as SVG and as Excalidraw scenes, so the client can edit them afterwards in a free tool rather than needing your licence. A deliverable that decays into an image the moment the engagement ends is worth less than one they can maintain.

First pass

Related

• Onboarding Engineers to a Codebase
  The first week is spent building a mental model that somebody already has. A diagram transfers it in an afternoon.
• Documenting Legacy Code
  Including the newest kind of legacy code: what a coding agent wrote for you over several sessions that nobody has looked at as a whole.
• Architecture Review
  Most of the effort in an architecture review goes into producing the diagrams, and most of those diagrams describe the system as remembered rather than as built.
• System Design Interview Preparation
  The diagram is the easy part. Interviews are decided by the tradeoffs you can defend when the interviewer pushes.