The Powerduck Blog

API engineering, from the spec out

Product updates, engineering notes, and guides for designing, debugging, testing, mocking, and serving MCP tools from one OpenAPI spec.

Browse the guides
release-notes 1 min read

Powerduck 1.4.0

This release adds unsigned Windows x64 and ia32 NSIS installers, improves document retry and MCP configuration handling, and fixes startup and stability issues.

Read article
AI Agents 5 min read

Your Agent Says Tests Pass. On Your Laptop. Not on CI.

An agent that runs tests locally and reports green is telling the truth — but only on its machine, where the .env, the local DB, and the cached node_modules exist. CI runs a clean checkout. The gap shows up in your pipeline.

Read article
ai 4 min read

The Test That Survives Its Own Implementation

When you ask an AI agent to add tests, it writes tests that pass on the first run. That's the problem. The sanity check is cheaper than you think: delete the implementation and see which tests still go green.

Read article
AI Agents 4 min read

Your Agent Leaves a Trail of Orphaned Dev Servers When It Says Done

An agent that says 'done' after starting a dev server, a watcher, or a docker compose stack often leaves those processes running in the background. By the next task, your machine is a graveyard of half-finished services.

Read article
ai 2 min read

Your agent runs the tests that are fast. The slow ones tell the truth.

When you tell an agent to 'run the tests,' it runs the subset that finishes in under thirty seconds. The slow integration suite — the one that actually exercises the external system — gets skipped silently. Here's the cheap habit that catches it.

Read article
ai 3 min read

Treat CLAUDE.md like a migration script, not a README

Instruction files used to be docs humans skimmed. Now they are runtime input an agent trusts literally. The rot that didn't matter in a README will derail your next agent run.

Read article