Environment lanes existed as seeded rows (production/preview/development)
with a per-service environment label, but there was no way to list,
create, or delete them. Adds the management surface and the switcher:
- GET /projects/:id/environments with live service counts (sqlc)
- POST /projects/:id/environments — lowercase dns-label names, 1-50
chars, unique per project (409 on dupe)
- DELETE /environments/:id — refuses while it holds services (409)
- Workspace service list gains env filter chips with counts plus an
inline "+ env" creator
- CLI: containr environments list|create|delete (--yes on delete);
MCP: containr_environments_list/create/delete (delete needs confirm)
- OpenAPI: new Environments tag + ProjectEnvironment schema
Live-verified: list counts, name validation, dupe 409, empty delete,
non-empty 409, CLI list.
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Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>