tenant_filter(model, account_id) is the canonical app-layer tenant
scoping expression. Every query on a tenant table must use it.
build_tree_access_filter and build_step_visibility_filter updated
to call tenant_filter() internally for the account_id match.
get_tenant_context is a FastAPI dependency that returns account_id
or raises 403 if the user has no account — prevents raw access to
current_user.account_id and centralises the null check.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
3c0374378c