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7d3b88b | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 | """Embedding generation for semantic memory retrieval.
Uses sentence-transformers to produce dense vector embeddings.
The model is loaded lazily on first call to avoid startup overhead.
"""
from __future__ import annotations
import logging
import threading
from typing import Any
logger = logging.getLogger(__name__)
# ── Constants ──────────────────────────────────────────────────────────────
MODEL_NAME = "all-MiniLM-L6-v2"
EMBEDDING_DIM = 384 # output dimension of all-MiniLM-L6-v2
# ── Lazy model loading ────────────────────────────────────────────────────
_model: Any = None
_model_lock = threading.Lock()
def is_available() -> bool:
"""Check whether sentence-transformers is installed."""
try:
import sentence_transformers # noqa: F401
return True
except ImportError:
return False
def _load_model() -> Any:
"""Load the sentence-transformer model (thread-safe, lazy)."""
global _model
if _model is not None:
return _model
with _model_lock:
# Double-check after acquiring lock
if _model is not None:
return _model
from sentence_transformers import SentenceTransformer
logger.info("[EMBEDDING] Loading model: %s …", MODEL_NAME)
_model = SentenceTransformer(MODEL_NAME)
logger.info("[EMBEDDING] Model loaded (dim=%d)", EMBEDDING_DIM)
return _model
def get_embedding(text: str) -> list[float]:
"""Generate a dense vector embedding for the given text.
Args:
text: The input text to embed.
Returns:
A list of floats (length == EMBEDDING_DIM).
Raises:
ValueError: If the input text is empty.
RuntimeError: If encoding fails.
"""
if not text or not text.strip():
raise ValueError("Cannot generate embedding for empty text")
try:
model = _load_model()
vector = model.encode(text, show_progress_bar=False, normalize_embeddings=True)
return vector.tolist()
except Exception as exc:
logger.error("[EMBEDDING] Encoding failed: %s", exc)
raise RuntimeError(f"Embedding generation failed: {exc}") from exc
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