Umbratools_2.md 5.0 replaces shared-tables-plus-RLS with one schema per
organization, because RLS was measured to be unenforceable twice: the
application connects as the table owner so the policies did not apply to it
(gate G2), and one app function was PUBLIC-executable until it was fixed by
hand against one database (defect B4). A model whose correctness depends on a
grant somebody remembers to make is not a boundary.
The classification comes before the SQL because the SQL's blast radius depends
on it, and the obvious reading of "move the tenant tables" is wrong for eight of
the tables carrying an organization_id. Four move: projects, project_authors,
project_publishers, invitations. The other twenty-six stay, each for a reason
read out of the actual columns and foreign keys rather than the table names.
Two findings the plan did not price, both recorded in the classification:
- user_roles cannot move. It is the index that resolves a session to an
organization, so putting it in a tenant schema means finding the tenant by
searching every tenant schema, on the login path. It also holds
platform-scope rows, which have no organization to belong to. So one table
stays shared, and 5.0's "no table is shared between organizations" is not
fully achievable while the session-to-tenant resolution is a table.
- moving projects forces dropping three foreign keys that point at it from
artifacts, jobs and user_roles, because a foreign key cannot name a table
whose schema depends on the row. That is the one place the decision costs a
database-enforced guarantee, and it is written down rather than papered over
with a trigger that would have to rediscover which tenant is meant.
The migration names each tenant schema from the organization id rather than
storing it, so a name cannot disagree with the rows and the rollback can rebuild
the organization_id column from the schema. It is idempotent - verified by
applying it twice - and the rollback is a file that runs rather than a comment
block, because a rollback for a data migration that only exists as a comment is a
rollback nobody runs. Both were applied to the scratch database, rolled back, and
applied again.
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