RAG: run ingestion in-process thread sharing warm embedder + compute lock

tests/python/test_rag_embeddings.py

@@ -0,0 +1,55 @@
+"""RAG embedder compute-lock wiring (no GPU / real model needed)."""
+
+import sys
+from pathlib import Path
+
+import numpy as np
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+STUDIO_BACKEND = REPO_ROOT / "studio" / "backend"
+if str(STUDIO_BACKEND) not in sys.path:
+    sys.path.insert(0, str(STUDIO_BACKEND))
+
+
+class _FakeModel:
+    """Records whether the shared compute lock was held during each call."""
+
+    def __init__(self, lock) -> None:
+        self._lock = lock
+        self.encode_held: bool | None = None
+        self.tokenize_held: bool | None = None
+
+    def encode(self, texts, **_kw):
+        self.encode_held = self._lock.locked()
+        return np.zeros((len(texts), 3), dtype = "float32")
+
+    def tokenize(self, _texts):
+        self.tokenize_held = self._lock.locked()
+        return {"input_ids": np.zeros((1, 5), dtype = "int64")}
+
+
+def test_encode_holds_compute_lock_then_releases(monkeypatch):
+    from core.rag import embeddings
+
+    fake = _FakeModel(embeddings._compute_lock)
+    monkeypatch.setattr(embeddings, "get_embedder", lambda *a, **k: fake)
+
+    out = embeddings.encode(["hello"])
+
+    assert fake.encode_held is True
+    assert embeddings._compute_lock.locked() is False
+    assert out.shape == (1, 3)
+
+
+def test_token_counter_holds_compute_lock_then_releases(monkeypatch):
+    from core.rag import embeddings
+
+    fake = _FakeModel(embeddings._compute_lock)
+    monkeypatch.setattr(embeddings, "get_embedder", lambda *a, **k: fake)
+
+    counter = embeddings.token_counter()
+    n = counter("hello world")
+
+    assert fake.tokenize_held is True
+    assert n == 5
+    assert embeddings._compute_lock.locked() is False