fix: close task3 qdrant and config validation gaps

harness/tht/adapters/vector/qdrant.py

@@ -188,6 +188,11 @@ class QdrantVectorStore:
     def existing_hashes(self, collection: str, kinds: list[str]) -> dict[str, str]:
         validate_collection(collection)
         validate_collection_kinds(collection, kinds)
+        if self._collection_lifecycle == "require_existing":
+            # Reconcile only after proving the exact existing collection contract.
+            # This keeps an initial 404 typed and prevents an incompatible empty
+            # collection from appearing healthy merely because there are no records.
+            self._ensure_collection(strict=False)
         points = self._scroll(
             [
                 *self._workspace_filter(),
@@ -209,7 +214,6 @@ class QdrantVectorStore:
 
     def upsert(self, collection: str, records: list[VectorWriteRecord]) -> int:
         validate_collection(collection)
-        self._ensure_collection(strict=True)
         points = []
         for write_record in records:
             validate_collection_kinds(collection, [write_record.record.kind])
@@ -228,6 +232,9 @@ class QdrantVectorStore:
                 }
             )
         try:
+            # Keep the preflight immediately adjacent to the mutation: a registry
+            # collection may disappear after reconciliation has read its hashes.
+            self._ensure_collection(strict=True)
             self._call(
                 "PUT",
                 f"/collections/{self._collection}/points?wait=true",
@@ -249,12 +256,23 @@ class QdrantVectorStore:
             self._semantic_kind_filter(kinds),
             {"key": "record_kind", "match": {"any": sorted(kinds)}},
         ]
+        if self._collection_lifecycle == "require_existing":
+            self._ensure_collection(strict=False)
         before = len(self._scroll(must))
-        self._call(
-            "POST",
-            f"/collections/{self._collection}/points/delete?wait=true",
-            {"filter": {"must": must}},
-        )
+        if self._collection_lifecycle == "require_existing":
+            self._ensure_collection(strict=False)
+        try:
+            self._call(
+                "POST",
+                f"/collections/{self._collection}/points/delete?wait=true",
+                {"filter": {"must": must}},
+            )
+        except VectorTransportError as exc:
+            if self._collection_lifecycle == "require_existing" and exc.status_code == 404:
+                raise SemanticIndexIncompatibleError(
+                    "Qdrant collection disappeared during semantic index deletion"
+                ) from exc
+            raise
         return before
 
     def delete_generation(self, collection: str, generation: str, workspace_id: str) -> int:
@@ -269,14 +287,25 @@ class QdrantVectorStore:
             {"key": "record_kind", "match": {"any": ["evidence"]}},
             {"key": "vector_generation", "match": {"value": generation}},
         ]
+        if self._collection_lifecycle == "require_existing":
+            self._ensure_collection(strict=False)
         before = len(
             self._scroll(must)
         )
-        self._call(
-            "POST",
-            f"/collections/{self._collection}/points/delete?wait=true",
-            {"filter": {"must": must}},
-        )
+        if self._collection_lifecycle == "require_existing":
+            self._ensure_collection(strict=False)
+        try:
+            self._call(
+                "POST",
+                f"/collections/{self._collection}/points/delete?wait=true",
+                {"filter": {"must": must}},
+            )
+        except VectorTransportError as exc:
+            if self._collection_lifecycle == "require_existing" and exc.status_code == 404:
+                raise SemanticIndexIncompatibleError(
+                    "Qdrant collection disappeared during semantic index deletion"
+                ) from exc
+            raise
         return before
 
     def list_evidence_generations(self, collection: str, workspace_id: str) -> list[str]: