ENGINEERING // ANDREW CARR
BLACK BOX
Engineering notes and the systems I run. Every claim demoable.
TRANSMITTING · 3 ENTRIES
Credentials Never Reach the Model
Publishing the WorkPulse MCP server: fourteen tools over a real invoicing API, two credential domains that never mix, batch rollback for every bulk write, and Streamable HTTP behind OAuth.
WorkPulse is the business-management app I run my own consulting through: clients, projects, time, invoices, expenses, pay periods. It has a REST API. For most of this year I've had a small MCP server sitting on top of that API so Claude Code and Claude Desktop can do the boring parts — "create an expense for $127.50 at Office Depot on the 20th, deductible" — without me tabbing into a form. Today I split it out of the private monorepo and published it.
READ →What an AI Facade Has to Actually Do
You do not govern generated code by reading it. Four things a real AI facade has to do — schema boundary, deterministic repair with receipts, fixtures that referee, an audit trail with no exceptions — each demoable against a Go binary in my closet.
I promised myself this post couldn't be written until it was true. It's true now — every claim below is a curl command against a Go binary running on a box in my closet.
READ →APR 3361
The number that started the whole containment project — and what it looks like today when the same mistake hits the facade.
Last month a local model read a credit-card statement and returned this:
READ →