ACI-044: The Suite Has a Blast Radius

Thesis

A test suite reaches past its assertions. It can bill a live model, migrate the project's own data or leave processes running while no assertion notices, and its green covers only what its fixtures vary and the tests someone chose to run. Force the isolated, deterministic setting in the test helper, where nobody has to remember it, and choose the tests from what the change can reach.

Story

In June 2026 a work package in Lamplight, an Elixir application built around a language model, removed some duplicate embedding code. Its coverage note said the embedding service's key was "never set in this repo". It was false. A gitignored config file held a real key, the config loader injected it into every development and test run, and no search of the repository could see it. After the change, every memory or training record a test created made a live, billed call. No assertion noticed; the only symptom was three runs in five failing on connection-pool contention. A separate verification agent traced the cause (Lamplight@ae8c3a00b, 2026-06-11). The repair gave the tests an offline, deterministic embedding model, tests on the stored vector, and one that fails if the seam is reverted to the live service.