Implement slice S3 of the §22 three-tier refactor: the four-layer
most-permissive scope-role resolver (§B.2) over {owner, contributor}
grants at {global, project, collection}, with the §22.5 visibility gate
enforced at the collection grain.
- migration 030: memberships.scope_type += 'global' (the global RFC
Contributor tier; sentinel scope_id '*').
- auth.effective_scope_role folds global → project → collection,
most-permissive, no negative override; can_read_collection /
can_contribute_in_collection / is_collection_superuser /
can_create_collection gate reads, writes, admin, and create.
- collection-grain visibility: a gated collection is hidden from the
public (404, omitted from the directory) yet visible+listed for a
scope-role holder; a collection may be set only as strict or stricter
than its project (public < unlisted < gated), validated at create and
clamped at the mirror.
- entry-scoped authority (mark-reviewed, graduate, branch read/contribute,
PR/discussion/contribution moderation) re-pointed from the project grain
to the entry's collection.
- create-collection authority widened to a project/global-scope grant
holder (§B.1), not only a deployment owner/admin.
Keystone reconciliation (session 0076): a plain granted account is a
granted *account*, not a write-everywhere global role; the implicit-public
write baseline is grandfathered onto the migration-seeded `default`
collection only, so the N=1 deployment loses no capability. Reinterprets
§B.1/§B.3 literally — flagged for the SPEC merge (S6).
Completes @S3 (C1.1–C1.8). Tests: test_s3_scope_roles_vertical.py (8 C.1
scenarios + visibility/strictness), test_migration_030_global_scope.py.
Full backend suite 493 passed.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>