Phase 1 Data Model: data_source → knowledge_base inheritance

The "data model" here is the OpenFGA authorization model (object types, relations, derived permissions, and the tuples that wire them). No application database schema changes.

Object types & relations

knowledge_base (parent — unchanged)

Relation	Type	Meaning
owner	direct: user, service_account	Creator/owner of the KB.
reader	direct: user, user:*, service_account, team#member, team#admin, external_group#member, slack_channel, webex_space	Can read/search. user:* = public.
ingestor	direct: user, service_account, team#member, team#admin, external_group#member	Can ingest/update content.
manager	direct: user, service_account, team#admin, organization#admin	Can administer/delete.
auditor	direct: user, service_account, team#admin	Read audit.
can_read	reader or can_ingest or can_manage or owner	Derived.
can_ingest	ingestor or can_manage or owner	Derived.
can_manage	manager or owner	Derived.

Grants are written here. This is the single source of truth for who-can-do-what on a datasource.

data_source (component — CHANGED)

Relation	Type	Meaning
parent_kb (new)	direct: knowledge_base	Wires this datasource to its KB for inheritance. Exactly one per datasource (1:1 today).
owner	direct: user, service_account	Direct component owner (rare).
reader	direct: user, user:*, service_account, team#member, team#admin, external_group#member	Direct component read (rare; usually inherited).
ingestor	direct: user, service_account, team#member, team#admin, external_group#member	Component-only ingest (the reason the type exists — Story 3).
manager	direct: user, service_account, team#admin, organization#admin	Direct component manage (rare).
auditor	direct: user, service_account, team#admin	Read audit.
can_read	reader or can_manage or owner or **can_read from parent_kb**	Derived; inherits KB read.
can_ingest	ingestor or can_manage or owner or **can_ingest from parent_kb**	Derived; inherits KB ingest.
can_delete	can_manage	Derived (unchanged).
can_manage	manager or owner or **can_manage from parent_kb**	Derived; inherits KB manage.
can_discover, can_use, can_write, can_audit	unchanged derivations	—

Only the three can_* derivations gain a ... from parent_kb branch and the new parent_kb relation is added. Direct relations are retained verbatim so component-only grants and any non-KB-backed datasource still work.

Relationships

user / team#member / team#admin / external_group#member / user:*
        │  (reader | ingestor | manager | owner)   ← grants written HERE
        ▼
   knowledge_base:<id>
        ▲
        │  parent_kb            ← one structural tuple per datasource
   data_source:<id>
        │  can_read / can_ingest / can_manage  = direct ∪ (inherited from parent_kb)
        ▼
   enforced by: BFF data_source#read filter + RAG server inject_kb_filter

Tuples

Structural (new, one per datasource):

data_source:<id>  parent_kb  knowledge_base:<id>

Access (written on the KB — unchanged shapes):

team:<slug>#member  reader     knowledge_base:<id>
team:<slug>#member  ingestor   knowledge_base:<id>
team:<slug>#admin   manager    knowledge_base:<id>
user:<sub>          owner      knowledge_base:<id>
user:*              reader     knowledge_base:<id>      # public (inherited by the datasource)

Component-only (optional, direct on data_source — Story 3):

team:<slug>#member  ingestor   data_source:<id>          # ingest without KB read

Validation / invariants

• INV-1: Each data_source:<id> has exactly one parent_kb edge (1:1 with its KB) after backfill. Datasources with no KB (none today) simply have no edge and rely on direct tuples.
• INV-2: data_source:<id>#can_read ⊇ knowledge_base:<id>#can_read (inheritance never narrows KB access).
• INV-3: A direct ingestor on data_source:<id> with no KB read grant yields can_ingest = true, can_read = false (component-only ingest is expressible — Story 3).
• INV-4: Removing a KB-level grant removes the inherited datasource permission with no separate data_source delete (FR-008).
• INV-5: Backfill is additive + idempotent; running it twice changes nothing (US2).

State transitions

Event	Tuple effect
Datasource created	Write data_source:<id> parent_kb knowledge_base:<id> (replaces the old access dual-write).
Team granted KB read/ingest/admin	Write KB grant only; datasource access follows by inheritance.
Team grant revoked	Delete KB grant only; inherited datasource access disappears.
Datasource made public	Write user:* reader knowledge_base:<id> (inherited).
Datasource un-published	Delete user:* reader knowledge_base:<id>.
Datasource deleted	Delete parent_kb edge + any direct data_source tuples (FR-010).