`_slim_canvas` filtered `n["data"]`, the React Flow shape the frontend store
holds. `GET /api/v1/canvas` has never sent that: a node is reported flat, so
the filter matched nothing and `get_canvas` returned an id and a node type per
node — no label, no address, no services. The three tests covering it fed a
hand-built nested payload, so they passed against a shape the backend does not
produce.
Fold `data` over the node and read both, so either form slims the same way.
`type` leaves `NODE_KEEP` — flat it is the node type, not a device fact, and it
is already reported as `node_type`; `parentId` becomes `parent_id`, the key the
API uses, normalized from either spelling.
The new tests are built on a full `NodeResponse` copied from a real response,
and the backend now pins that wire shape from its side so the two move together.
ha-relevant: no
Pouzor
d40f73b85c