Add rebuild --set-embedder to reconcile embedder identity

CHANGELOG.md

@@ -1,9 +1,13 @@
 # Changelog
 ## [Unreleased]
 
+### Added
+
+- `haiku-rag rebuild --set-embedder`: adopt the current embedder identity (provider/name) without re-embedding, when the vector dimension is unchanged.
+
 ### Fixed
 
-- Opening a database no longer writes to it: reads no longer rewrite the stored embedding settings or change the stored version, and the version is never downgraded.
+- Opening a database no longer writes to it: reads no longer rewrite the stored embedding settings or change the stored version, and the version is never downgraded. Embedding provider/name drift (matching `vector_dim`) warns on read-only opens and raises `ConfigMismatchError` on writable opens; reconcile with `rebuild --set-embedder`.
 
 ## [0.54.0] - 2026-06-04
 

docs/cli.md

@@ -373,6 +373,9 @@ haiku-rag rebuild --title-only
 # Run the VLM over already-stored picture bytes and patch descriptions
 # into the docling blob. Skips the docling parse entirely.
 haiku-rag rebuild --descriptions
+
+# Adopt the current embedder identity without re-embedding (same vector dimension)
+haiku-rag rebuild --set-embedder
 ```
 
 **Rebuild modes:**
@@ -384,6 +387,9 @@ haiku-rag rebuild --descriptions
 | Embed only | `--embed-only` | Changed embedding model or vector dimensions |
 | Title only | `--title-only` | Generate titles for documents without one |
 | Descriptions | `--descriptions` | Add VLM picture descriptions to an existing database |
+| Set embedder | `--set-embedder` | Same model, different serving stack (e.g. Ollama to vLLM); vector dimension unchanged |
+
+**`--set-embedder` mode** updates the stored embedding provider/name to match the current config without re-embedding, valid only when the vector dimension is unchanged. Use it when the same model is served by a different stack so the recorded identity stops drifting from the config. A changed vector dimension is rejected; regenerate embeddings with `--embed-only` or a full rebuild instead.
 
 **`--descriptions` mode** runs the configured VLM (`processing.conversion_options.picture_description.model`) over the picture bytes already stored in `document_items.picture_data`, patches each description into the stored docling blob's `pictures[i].meta.description.text`, and re-chunks + re-embeds so chunk text reflects the new descriptions. Requires `processing.pictures: description` in the config. Idempotent: pictures that already carry a description are skipped, so the operation is safe to re-run after a partial failure. The docling parse is skipped entirely. Only the VLM time is paid.
 

haiku_rag_slim/haiku/rag/app.py

@@ -506,6 +506,14 @@ class HaikuRAGApp:  # pragma: no cover
             read_only=self.read_only,
             before=self.before,
         ) as client:
+            if mode == RebuildMode.SET_EMBEDDER:
+                async for _ in client.rebuild_database(mode=mode):
+                    pass
+                self.console.print(
+                    "[bold green]Stored embedder settings updated.[/bold green]"
+                )
+                return
+
             documents = await client.list_documents()
             total_docs = len(documents)
 

haiku_rag_slim/haiku/rag/cli.py

@@ -476,14 +476,23 @@ def rebuild(
             "parse entirely. Requires processing.pictures='description'."
         ),
     ),
+    set_embedder: bool = typer.Option(
+        False,
+        "--set-embedder",
+        help=(
+            "Adopt the current embedder identity without re-embedding, when the "
+            "vector dimension is unchanged. Use after swapping the serving stack "
+            "for the same model (e.g. Ollama to vLLM)."
+        ),
+    ),
 ):
     from haiku.rag.client import RebuildMode
 
-    exclusive = sum([embed_only, rechunk, title_only, descriptions])
+    exclusive = sum([embed_only, rechunk, title_only, descriptions, set_embedder])
     if exclusive > 1:
         typer.echo(
-            "Error: --embed-only, --rechunk, --title-only, and --descriptions "
-            "are mutually exclusive"
+            "Error: --embed-only, --rechunk, --title-only, --descriptions, and "
+            "--set-embedder are mutually exclusive"
         )
         raise typer.Exit(1)
 
@@ -495,6 +504,8 @@ def rebuild(
         mode = RebuildMode.TITLE_ONLY
     elif descriptions:  # pragma: no cover
         mode = RebuildMode.DESCRIPTIONS
+    elif set_embedder:  # pragma: no cover
+        mode = RebuildMode.SET_EMBEDDER
     else:  # pragma: no cover
         mode = RebuildMode.FULL
 

haiku_rag_slim/haiku/rag/client/__init__.py

@@ -49,6 +49,8 @@ class RebuildMode(Enum):
     TITLE_ONLY = "title_only"  # Only generate titles for untitled documents
     DESCRIPTIONS = "descriptions"  # Run the VLM over already-stored picture
     # bytes, patch descriptions into the docling blob, then re-chunk + re-embed.
+    SET_EMBEDDER = "set_embedder"  # Adopt the current embedder identity without
+    # re-embedding, when the vector dimension is unchanged.
 
 
 class HaikuRAG:

haiku_rag_slim/haiku/rag/client/rebuild.py

@@ -72,6 +72,10 @@ async def rebuild_database(
     if mode is None:
         mode = RebuildMode.FULL
 
+    if mode == RebuildMode.SET_EMBEDDER:
+        await _set_embedder(client)
+        return
+
     # Resolve any leftover staging/marker tables from a previously
     # interrupted rebuild. Returns True only when phase 1 was already
     # complete and the current mode is EMBED_ONLY, in which case we resume
@@ -131,6 +135,29 @@ async def rebuild_database(
             logger.warning("Post-rebuild vacuum failed", exc_info=True)
 
 
+async def _set_embedder(client: "HaikuRAG") -> None:
+    """Adopt the current embedder identity without re-embedding.
+
+    Only valid when the vector dimension is unchanged — the stored vectors stay
+    usable, so just the recorded provider/name are updated. A changed dimension
+    requires regenerating every embedding via a full rebuild.
+    """
+    from haiku.rag.store.repositories.settings import ConfigMismatchError
+
+    settings_repo = SettingsRepository(client.store)
+    stored = await settings_repo.get_current_settings()
+    stored_dim = stored.get("embeddings", {}).get("model", {}).get("vector_dim")
+    current_dim = client._config.embeddings.model.vector_dim
+
+    if stored_dim is not None and current_dim != stored_dim:
+        raise ConfigMismatchError(
+            f"Stored vector dimension {stored_dim} differs from current "
+            f"{current_dim}; embeddings must be regenerated. Run 'haiku-rag rebuild'."
+        )
+
+    await settings_repo.save_current_settings()
+
+
 async def _hydrate(
     client: "HaikuRAG", light_docs: list[Document]
 ) -> AsyncGenerator[Document, None]:

tests/test_rebuild.py

@@ -960,3 +960,84 @@ async def test_rebuild_descriptions_raises_when_blob_is_missing(
         with pytest.raises(ValueError, match="rebuild --descriptions requires"):
             async for _ in rag.rebuild_database(mode=RebuildMode.DESCRIPTIONS):
                 pass
+
+
+async def _add_chunk(client: HaikuRAG, vector: list[float]) -> str:
+    """Insert a chunk row directly, bypassing the embedder."""
+    record = client.store.ChunkRecord(
+        id="chunk-1",
+        document_id="doc-1",
+        content="hello",
+        content_fts="hello",
+        metadata="{}",
+        order=0,
+        vector=vector,
+    )
+    await client.store.chunks_table.add([record])
+    return record.id
+
+
+async def _stored_embedding_name(client: HaikuRAG) -> str:
+    from haiku.rag.store.repositories.settings import SettingsRepository
+
+    settings = await SettingsRepository(client.store).get_current_settings()
+    return settings["embeddings"]["model"]["name"]
+
+
+async def test_rebuild_set_embedder_adopts_identity_without_reembedding(temp_db_path):
+    """SET_EMBEDDER updates stored embedder identity and leaves vectors untouched."""
+    from haiku.rag.config import AppConfig
+
+    dim = AppConfig().embeddings.model.vector_dim
+    sentinel = [0.5] * dim
+
+    async with HaikuRAG(temp_db_path, create=True) as client:
+        await _add_chunk(client, sentinel)
+
+    drift = AppConfig()
+    drift.embeddings.model.name = "different-model"
+
+    async with HaikuRAG(temp_db_path, config=drift, skip_validation=True) as client:
+        async for _ in client.rebuild_database(mode=RebuildMode.SET_EMBEDDER):
+            pass
+
+        assert await _stored_embedding_name(client) == "different-model"
+
+        rows = (await client.store.chunks_table.query().to_arrow()).to_pylist()
+        assert len(rows) == 1
+        assert rows[0]["vector"] == pytest.approx(sentinel)
+
+
+async def test_rebuild_set_embedder_works_on_empty_database(temp_db_path):
+    """SET_EMBEDDER reconciles even with no documents (preflight must be bypassed)."""
+    from haiku.rag.app import HaikuRAGApp
+    from haiku.rag.config import AppConfig
+
+    async with HaikuRAG(temp_db_path, create=True):
+        pass
+
+    drift = AppConfig()
+    drift.embeddings.model.name = "different-model"
+
+    app = HaikuRAGApp(db_path=temp_db_path, config=drift)
+    await app.rebuild(mode=RebuildMode.SET_EMBEDDER)
+
+    async with HaikuRAG(temp_db_path, config=drift, skip_validation=True) as client:
+        assert await _stored_embedding_name(client) == "different-model"
+
+
+async def test_rebuild_set_embedder_raises_on_vector_dim_mismatch(temp_db_path):
+    """SET_EMBEDDER refuses when the vector dimension changed — a full rebuild is needed."""
+    from haiku.rag.config import AppConfig
+    from haiku.rag.store.repositories.settings import ConfigMismatchError
+
+    async with HaikuRAG(temp_db_path, create=True):
+        pass
+
+    drift = AppConfig()
+    drift.embeddings.model.vector_dim = 9999
+
+    async with HaikuRAG(temp_db_path, config=drift, skip_validation=True) as client:
+        with pytest.raises(ConfigMismatchError):
+            async for _ in client.rebuild_database(mode=RebuildMode.SET_EMBEDDER):
+                pass