Follow-up to PR #778 — `collection_exists()` is also denied by Qdrant
Cloud on a collection-scoped JWT, so the multi-tenant fix needs to go
one step further: use `get_collection(name)` (the underlying GET
`/collections/{name}` call) and treat a 404 `UnexpectedResponse` as
the "doesn't exist" signal. That endpoint is the only existence-probe
Qdrant permits on a collection-scoped JWT — listing or probing
collection metadata cluster-wide is a tenant-isolation boundary by
design.
Hit during Astrolabe Cloud smoke17 with the post-#778 image:
qdrant_client.http.exceptions.UnexpectedResponse: 403 (Forbidden)
raw response: {"error":"forbidden"}
File "qdrant_client.py", line 84, in get_qdrant_client
collection_present = await _qdrant_client.collection_exists(...)
Folds the existence check into the same `get_collection()` call that
already runs immediately afterward for dimension validation, so the
new path is also one fewer round-trip on the happy path.
Cold-start (collection genuinely missing) behavior is unchanged: 404
→ `collection_info` is None → fall through to `create_collection()`.
Whether `create_collection` succeeds is an orthogonal concern (managed
multi-tenant setups pre-provision collections externally; admin-key
single-tenant setups can create on the fly).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
