POST /v1/groups is authorized for any GROUP_MANAGER, because a conditional 'manage' rule passes the route guard #1468

Summary

POST /v1/groups is authorized for any GROUP_MANAGER, so a group manager can create arbitrary new groups.

Why

apps/api/src/auth/ability.factory.ts grants a group manager:

ability.can('manage', 'Group', { id: { in: groupIds } });

JwtAuthGuard evaluates @RouteAccess against the subject type only (ability.can(action, subject) with a subject name, not a row), and CASL ignores a rule's conditions for a type-level check. So the condition is invisible to the guard:

can('create', 'Group') => true      can('create', 'User') => false
can('update', 'Group') => true      can('manage', 'all')  => false
can('delete', 'Group') => true

(Confirmed by building that exact rule set with @casl/prisma and calling can directly.)

Every sibling route survives this because the service re-checks against real rows — accessibleQuery(ability, ...) in the Prisma where, i.e. Layer 2 in .agents/docs/architecture/auth-and-permissions.md. GroupsService.create is the exception: it takes no ability parameter at all, and a create has no existing row to scope against, so nothing narrows it.

Repro

POST /v1/groups with a group manager's access token → 201.

Also reachable through the UI: /admin/groups/create renders for a group manager (no route-level role check exists — see the companion issue), so the form submits successfully and redirects to the group list.

Impact

Bounded, but real. The created group is instance-wide, is connected to every non-repo instrument, occupies the unique-name space, and appears in every admin's group list.

It is not a data-access escalation: permissions are frozen into the JWT at login, so the creator is not a member of the group they just created and cannot read anything through it.

Suggested fix

Either:

1. Narrow @RouteAccess on GroupsController.create to { action: 'manage', subject: 'all' }, matching who the UI intends to expose it to and the sibling PATCH /v1/setup; or
2. Give GroupsService.create an { ability } parameter and check the payload with forcedAppSubject('Group', ...), the way files.service.ts does.

(1) is smaller and matches existing convention. Worth a unit test in src/auth/__tests__/ability.factory.test.ts asserting the deny case either way.

Notes

Found while writing the Playwright suite (branch e2e-tests). testing/src/specs/authorization.spec.ts now has a server-side authorization block asserting the whole family of privileged requests is refused for non-admin roles; POST /v1/groups is deliberately excluded from that table so the suite does not lock in this behaviour. Add it back when this is fixed.