docs(changelog): note the Chroma embedding-vector fix under 3.7.0

CHANGELOG.md

@@ -24,6 +24,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ### Bug Fixes
 
+- **Mining works again on the default Chroma backend.** Once Chroma began declaring `requires_explicit_embeddings`, every write started routing through `EmbeddingCollection`, whose `_embed_texts` built rows with `list(ndarray)` — that unpacks into `np.float32` *scalars*, which chromadb rejects outright (`Expected embeddings to be a list of floats or ints, a list of lists, a numpy array, or a list of numpy arrays`). `mine`, and every other write against a default palace, aborted on the first drawer. Vectors now convert to real Python floats. The suite was structurally blind to this: conftest's autouse embedding fixture replaces `_embed_texts` itself for every module outside `test_embedding` / `test_embeddinggemma`, so the defective function was never executed under test — the regression tests therefore live in `test_embedding.py`, where that stub does not apply. (#2187)
 - **ChatGPT data exports are parsed instead of stored as raw JSON.** A real `conversations.json` is a top-level array of conversations, which no parser claimed, so `mine --mode convos` chunked the raw JSON and lost every speaker turn while reporting success. Each conversation now normalizes to its own transcript, as Claude.ai privacy exports already do, so per-conversation dedup survives a re-export. The ChatGPT parser also type-checks its nested shapes, so an unrelated array carrying a `mapping` key is declined instead of raising. (#2160)
 - **Local backends enforce process-lifetime single-writer ownership.** File-backed and unknown backends require one writer owner for the full process lifetime (daemon holds the lease until workers exit; writable MCP HTTP acquires ownership before bind and refuses startup when blocked). Read-only MCP may coexist; `sqlite_exact` opens genuine query-only/immutable readers; remote Milvus/Zilliz remain multi-process. Addresses multi-writer SQLite/WAL corruption from MCP HTTP + daemon + mine topologies. (#2079, #2045)
 - **Chroma HNSW write defaults match chromadb** (`batch_size=100` / `sync_threshold=1000`) instead of the old 2/2 bloat guard that rewrote segments thousands of times on large mines. (#2107, #2106)