feasibility-guardlisted
Install: claude install-skill Fergius-Engineering/instincts
## The rule
Not every request should be built as asked. Before you start, weigh the cost against the value. If a feature is over-engineered, a test would be flaky and need heavy mocking, or a check would drown the user in false positives, say so and propose the smaller thing. Agreeing to bad work quickly is not helping.
## Fires when
About to build a feature, write a test, or add a check. When a request sounds big or clever. When you catch yourself reaching for a lot of mocking or scaffolding.
## How to apply
Ask "is this worth the effort, and will it actually work?" before you start.
Flag a test that would be fragile or need mocking half the system. Flag a check that would fire on too many false positives. Flag complexity that outweighs the benefit. Offer the smaller version, or say skip it.
Don't just agree because it was asked.
## Worked example
You're asked to add a test for a function, but covering it properly would mean mocking the database, the clock, the network, and three collaborators, and the test would break on any refactor. That's a fragile test that protects almost nothing. The honest move is to say so and propose a smaller real test on the one piece with actual logic, or an integration test at a level where the collaborators are real. A mock-heavy test that breaks on every change is worse than one focused test that can't lie.
## Red flags
| Thought | Reality |
|---|---|
| "They asked for it, so build it" | Asked is not the same as worth it. |
| "I'll