docs: a classifier key shown as set may still not work

The controller can only see that the leaf exists, so a key under the wrong field name or a deleted latest version still shows as set.

docs/2-handbook/swarm/services.md

@@ -353,7 +353,8 @@ below). Set `deploy.review-classifier.enable` directly to override either way.
 The operator sets the key of the runtime the swarm settings choose in the
 swarm UI: the **classifier settings** card on `/jobs` takes a key for the
 chosen runtime and shows whether one exists and when it changed, never the
-key. You can also write the same two keys in the secret store's UI under the
+key. "Set" means a key was written, not that it works: a run with a bad key
+still fails. You can also write the same two keys in the secret store's UI under the
 OIDC login, field `api_key`:
 
 - the API key runtime's Anthropic key at

docs/4-implementation/swarm/review-classifier.md

@@ -309,6 +309,10 @@ the key. Every error is problem+json: **400** for a body that isn't this shape,
 a runtime that isn't one of the two or a refused key, **401** for no
 `Remote-User`, **503** when the store is unreachable or refuses.
 
+`set` means the leaf's metadata exists. It doesn't mean the key works: a leaf
+written by hand under another field name, or one whose latest version was
+deleted, still shows as set, because the controller can't read a value to check.
+
 The classifier reads the leaf on every run, so a new key applies from the next
 run. The operator can still write the leaves in the secret store's UI
 ([`services.md`](../../2-handbook/swarm/services.md#review-classifier)).