A feature can be complete on both sides and unreachable in the middle

A client-side command and its server route had both been merged and were individually correct, yet the feature 404d on every deployment. Three independent gaps sat between them: the server flag defaulted off by design, the deployment file listed container environment variables as an explicit allow-list so setting the flag externally never reached the process, and no volume was declared so anything the route did write would vanish on the next image pull. None of the three is a bug in either component, and unit tests on both sides pass regardless. When a feature is reported as not working despite the code being present, check the config path end to end: is the switch reachable, does the value actually arrive in the process, and does what it produces survive a restart. The allow-list trap in particular is silent -- the variable interpolates fine in the deployment file and simply never appears in the container.