feat(evidence): add Qdrant BM25 vector in place

2026-08-24 18:01:46 +02:00
parent ae0976a4aa
commit 0e9add09a9
11 changed files with 320 additions and 14 deletions
@@ -58,6 +58,20 @@ tht --installation <absolute>/thothii-installation.yaml workspace vector rebuild
  performs the guarded rebuild; rebuild state is written before deletion and the
  collection is verified after recreation. No prefix matching or global Qdrant
  mutation is performed.
+
+## Additive BM25 for Evidence
+
+- Only `workspace preprocess evidence` (and the Evidence portion of `workspace preprocess run`)
+  may add the named sparse vector `bm25` with Qdrant modifier `idf`.
+- The upgrade uses Qdrant's additive named-vector operation. It preserves the existing unnamed
+  dense vector and never deletes, renames, or rebuilds the shared collection.
+- Session readiness remains read-only with respect to BM25. Schema, Memory, and solved-question
+  records therefore continue to use their existing dense-only points during and after an Evidence
+  upgrade.
+- A missing `bm25` is added and reread before Evidence preprocessing starts. An existing definition
+  other than `modifier: idf` fails as `semantic_index_incompatible` without any collection mutation.
+  If a later Evidence candidate fails, the compatible additive schema remains in place; it does not
+  make the dense-only records unavailable.
 ```

 ## Curated FK annotations (P5)