Set or remove a custom deployment's environment variables

Edits the deployment's own variables. Send set (an object to upsert; keys are upper-cased) and/or unset (a list of names to remove), or replace to declare the whole set at once. At least one of them is required.

Platform-managed keys are ignored in set and cannot be unset — the response lists any you passed under ignored_keys rather than failing the call. A value equal to the mask token means "leave this one alone", so a read-modify-write round trip does not destroy secrets the read masked.

Each value is one line of valid UTF-8 text, at most 32 KiB, with no control characters. $ and # are refused with 400: the app's environment file is read verbatim, where $ triggers variable substitution and # starts a comment. Names starting with COMPOSE_ or DOCKER_ are refused too, because they steer the container engine itself.

Saving does not restart anything: new values reach the container on the next deploy. Call POST /platform/deployments/custom/{id}/redeploy to apply them now — that keeps the same domain and port.