feat: add configurable multilingual embedding model support

mempalace/cli.py

@@ -33,7 +33,7 @@
 import argparse
 from pathlib import Path
 
-from .config import MempalaceConfig
+from .config import MempalaceConfig, get_embedding_function
 
 
 def cmd_init(args):
@@ -175,8 +175,9 @@ def cmd_repair(args):
 
     # Try to read existing drawers
     try:
+        ef = get_embedding_function()
         client = chromadb.PersistentClient(path=palace_path)
-        col = client.get_collection("mempalace_drawers")
+        col = client.get_collection("mempalace_drawers", embedding_function=ef)
         total = col.count()
         print(f"  Drawers found: {total}")
     except Exception as e:
@@ -213,7 +214,7 @@ def cmd_repair(args):
 
     print("  Rebuilding collection...")
     client.delete_collection("mempalace_drawers")
-    new_col = client.create_collection("mempalace_drawers")
+    new_col = client.create_collection("mempalace_drawers", embedding_function=ef)
 
     filed = 0
     for i in range(0, len(all_ids), batch_size):
@@ -287,8 +288,9 @@ def cmd_compress(args):
 
     # Connect to palace
     try:
+        ef = get_embedding_function()
         client = chromadb.PersistentClient(path=palace_path)
-        col = client.get_collection("mempalace_drawers")
+        col = client.get_collection("mempalace_drawers", embedding_function=ef)
     except Exception:
         print(f"\n  No palace found at {palace_path}")
         print("  Run: mempalace init <dir> then mempalace mine <dir>")
@@ -359,7 +361,9 @@ def cmd_compress(args):
     # Store compressed versions (unless dry-run)
     if not args.dry_run:
         try:
-            comp_col = client.get_or_create_collection("mempalace_compressed")
+            comp_col = client.get_or_create_collection(
+                "mempalace_compressed", embedding_function=ef
+            )
             for doc_id, compressed, meta, stats in compressed_entries:
                 comp_meta = dict(meta)
                 comp_meta["compression_ratio"] = round(stats["ratio"], 1)

mempalace/config.py

@@ -5,10 +5,13 @@
 """
 
 import json
+import logging
 import os
 import re
 from pathlib import Path
 
+logger = logging.getLogger("mempalace")
+
 
 # ── Input validation ──────────────────────────────────────────────────────────
 # Shared sanitizers for wing/room/entity names. Prevents path traversal,
@@ -197,6 +200,14 @@ def init(self):
                 pass
         return self._config_file
 
+    @property
+    def embedding_model(self):
+        """Configured embedding model name, or None for ChromaDB default."""
+        env_val = os.environ.get("MEMPALACE_EMBEDDING_MODEL")
+        if env_val:
+            return env_val
+        return self._file_config.get("embedding_model", None)
+
     def save_people_map(self, people_map):
         """Write people_map.json to config directory.
 
@@ -207,3 +218,46 @@ def save_people_map(self, people_map):
         with open(self._people_map_file, "w") as f:
             json.dump(people_map, f, indent=2)
         return self._people_map_file
+
+
+# ── Embedding function singleton ─────────────────────────────────────────────
+
+_embedding_function = None
+_embedding_function_resolved = False
+
+
+def get_embedding_function(config=None):
+    """Return the configured ChromaDB embedding function, or None for default.
+
+    Checks MEMPALACE_EMBEDDING_MODEL env var first, then config.json
+    ``embedding_model`` key.  When a model name is found, attempts to import
+    ``SentenceTransformerEmbeddingFunction`` from chromadb.  If
+    sentence-transformers is not installed the import will fail and we fall
+    back to None (ChromaDB's built-in default), logging a warning.
+
+    The result is cached so the function is only resolved once per process.
+    """
+    global _embedding_function, _embedding_function_resolved
+    if _embedding_function_resolved:
+        return _embedding_function
+
+    _embedding_function_resolved = True
+
+    cfg = config or MempalaceConfig()
+    model_name = cfg.embedding_model
+    if not model_name:
+        return None
+
+    try:
+        from chromadb.utils.embedding_functions import SentenceTransformerEmbeddingFunction
+
+        _embedding_function = SentenceTransformerEmbeddingFunction(model_name=model_name)
+        logger.info("Using embedding model: %s", model_name)
+    except Exception:
+        logger.warning(
+            "sentence-transformers not installed — falling back to ChromaDB default. "
+            "Install with: pip install mempalace[multilingual]"
+        )
+        _embedding_function = None
+
+    return _embedding_function

mempalace/layers.py

@@ -23,7 +23,7 @@
 
 import chromadb
 
-from .config import MempalaceConfig
+from .config import MempalaceConfig, get_embedding_function
 
 
 # ---------------------------------------------------------------------------
@@ -92,7 +92,9 @@ def generate(self) -> str:
         """Pull top drawers from ChromaDB and format as compact L1 text."""
         try:
             client = chromadb.PersistentClient(path=self.palace_path)
-            col = client.get_collection("mempalace_drawers")
+            col = client.get_collection(
+                "mempalace_drawers", embedding_function=get_embedding_function()
+            )
         except Exception:
             return "## L1 — No palace found. Run: mempalace mine <dir>"
 
@@ -197,7 +199,9 @@ def retrieve(self, wing: str = None, room: str = None, n_results: int = 10) -> s
         """Retrieve drawers filtered by wing and/or room."""
         try:
             client = chromadb.PersistentClient(path=self.palace_path)
-            col = client.get_collection("mempalace_drawers")
+            col = client.get_collection(
+                "mempalace_drawers", embedding_function=get_embedding_function()
+            )
         except Exception:
             return "No palace found."
 
@@ -261,7 +265,9 @@ def search(self, query: str, wing: str = None, room: str = None, n_results: int
         """Semantic search, returns compact result text."""
         try:
             client = chromadb.PersistentClient(path=self.palace_path)
-            col = client.get_collection("mempalace_drawers")
+            col = client.get_collection(
+                "mempalace_drawers", embedding_function=get_embedding_function()
+            )
         except Exception:
             return "No palace found."
 
@@ -317,7 +323,9 @@ def search_raw(
         """Return raw dicts instead of formatted text."""
         try:
             client = chromadb.PersistentClient(path=self.palace_path)
-            col = client.get_collection("mempalace_drawers")
+            col = client.get_collection(
+                "mempalace_drawers", embedding_function=get_embedding_function()
+            )
         except Exception:
             return []
 
@@ -438,7 +446,9 @@ def status(self) -> dict:
         # Count drawers
         try:
             client = chromadb.PersistentClient(path=self.palace_path)
-            col = client.get_collection("mempalace_drawers")
+            col = client.get_collection(
+                "mempalace_drawers", embedding_function=get_embedding_function()
+            )
             count = col.count()
             result["total_drawers"] = count
         except Exception:

mempalace/mcp_server.py

@@ -26,7 +26,7 @@
 from datetime import datetime
 from pathlib import Path
 
-from .config import MempalaceConfig, sanitize_name, sanitize_content
+from .config import MempalaceConfig, sanitize_name, sanitize_content, get_embedding_function
 from .version import __version__
 from .searcher import search_memories
 from .palace_graph import traverse, find_tunnels, graph_stats
@@ -116,11 +116,16 @@ def _get_collection(create=False):
     """Return the ChromaDB collection, caching the client between calls."""
     global _collection_cache
     try:
+        ef = get_embedding_function()
         client = _get_client()
         if create:
-            _collection_cache = client.get_or_create_collection(_config.collection_name)
+            _collection_cache = client.get_or_create_collection(
+                _config.collection_name, embedding_function=ef
+            )
         elif _collection_cache is None:
-            _collection_cache = client.get_collection(_config.collection_name)
+            _collection_cache = client.get_collection(
+                _config.collection_name, embedding_function=ef
+            )
         return _collection_cache
     except Exception:
         return None

mempalace/miner.py

@@ -17,6 +17,7 @@
 
 import chromadb
 
+from .config import get_embedding_function
 from .palace import SKIP_DIRS, get_collection, file_already_mined
 
 READABLE_EXTENSIONS = {
@@ -51,8 +52,8 @@
     "package-lock.json",
 }
 
-CHUNK_SIZE = 800  # chars per drawer
-CHUNK_OVERLAP = 100  # overlap between chunks
+CHUNK_SIZE = 450  # chars per drawer
+CHUNK_OVERLAP = 50  # overlap between chunks
 MIN_CHUNK_SIZE = 50  # skip tiny chunks
 MAX_FILE_SIZE = 10 * 1024 * 1024  # 10 MB — skip files larger than this
 
@@ -615,8 +616,9 @@ def mine(
 def status(palace_path: str):
     """Show what's been filed in the palace."""
     try:
+        ef = get_embedding_function()
         client = chromadb.PersistentClient(path=palace_path)
-        col = client.get_collection("mempalace_drawers")
+        col = client.get_collection("mempalace_drawers", embedding_function=ef)
     except Exception:
         print(f"\n  No palace found at {palace_path}")
         print("  Run: mempalace init <dir> then mempalace mine <dir>")

mempalace/palace.py

@@ -7,6 +7,8 @@
 import os
 import chromadb
 
+from .config import get_embedding_function
+
 SKIP_DIRS = {
     ".git",
     "node_modules",
@@ -41,11 +43,12 @@ def get_collection(palace_path: str, collection_name: str = "mempalace_drawers")
         os.chmod(palace_path, 0o700)
     except (OSError, NotImplementedError):
         pass
+    ef = get_embedding_function()
     client = chromadb.PersistentClient(path=palace_path)
     try:
-        return client.get_collection(collection_name)
+        return client.get_collection(collection_name, embedding_function=ef)
     except Exception:
-        return client.create_collection(collection_name)
+        return client.create_collection(collection_name, embedding_function=ef)
 
 
 def file_already_mined(collection, source_file: str, check_mtime: bool = False) -> bool:

mempalace/palace_graph.py

@@ -16,16 +16,17 @@
 """
 
 from collections import defaultdict, Counter
-from .config import MempalaceConfig
+from .config import MempalaceConfig, get_embedding_function
 
 import chromadb
 
 
 def _get_collection(config=None):
     config = config or MempalaceConfig()
     try:
+        ef = get_embedding_function()
         client = chromadb.PersistentClient(path=config.palace_path)
-        return client.get_collection(config.collection_name)
+        return client.get_collection(config.collection_name, embedding_function=ef)
     except Exception:
         return None
 

mempalace/searcher.py

@@ -11,6 +11,8 @@
 
 import chromadb
 
+from .config import get_embedding_function
+
 logger = logging.getLogger("mempalace_mcp")
 
 
@@ -24,8 +26,9 @@ def search(query: str, palace_path: str, wing: str = None, room: str = None, n_r
     Optionally filter by wing (project) or room (aspect).
     """
     try:
+        ef = get_embedding_function()
         client = chromadb.PersistentClient(path=palace_path)
-        col = client.get_collection("mempalace_drawers")
+        col = client.get_collection("mempalace_drawers", embedding_function=ef)
     except Exception:
         print(f"\n  No palace found at {palace_path}")
         print("  Run: mempalace init <dir> then mempalace mine <dir>")
@@ -98,8 +101,9 @@ def search_memories(
     Used by the MCP server and other callers that need data.
     """
     try:
+        ef = get_embedding_function()
         client = chromadb.PersistentClient(path=palace_path)
-        col = client.get_collection("mempalace_drawers")
+        col = client.get_collection("mempalace_drawers", embedding_function=ef)
     except Exception as e:
         logger.error("No palace found at %s: %s", palace_path, e)
         return {

pyproject.toml

@@ -39,6 +39,7 @@ mempalace = "mempalace:main"
 
 [project.optional-dependencies]
 dev = ["pytest>=7.0", "pytest-cov>=4.0", "ruff>=0.4.0", "psutil>=5.9"]
+multilingual = ["sentence-transformers>=3.0"]
 spellcheck = ["autocorrect>=2.0"]
 
 [dependency-groups]