fix(python): give each JinaEmbeddings instance its own session (#4547)

`JinaEmbeddings` stores its `requests` session in a `ClassVar`. The
first instance builds the session with its own API key, and every later
instance reuses that session. So a second instance with a different
`api_key` sends the first instance's key.

## Fix

The session is now a per-instance `cached_property`, the same pattern
`OpenAIEmbeddings` uses for `_openai_client`. `_init_client` and the
`ClassVar` are gone.

An instance with no `api_key` and no `JINA_API_KEY` now raises the
missing-key error. Before, it reused the session of an earlier instance
and sent that instance's key.

## Tests

`test_jina_embeddings_use_their_own_api_key` creates two instances with
different keys through the registry. It stubs `requests.Session.post`
and records the `Authorization` header of each request.

- On `main`, the test fails because both requests send `Bearer key-a`.
With the fix, it passes.
- `test_embeddings.py`: 18 passed, 8 skipped.
- An instance still pickles after the session exists, and
`safe_model_dump()` still returns only `api_key`.
- On pydantic 2.7.4, the minimum version, a model with the same
`cached_property` gets one session per instance and leaves it out of
`model_dump()`.
- `ruff format --check` and `ruff check` (0.9.9) pass on the changed
files.
- I did not build the native extension. I ran the tests against the
lancedb 0.40.0 wheel with the changed file copied over it. In that
wheel, `embeddings/jinaai.py` is byte-identical to `main` before this
change.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

python/python/lancedb/embeddings/jinaai.py

@@ -5,9 +5,10 @@
 import os
 import io
 import base64
+from functools import cached_property
 from urllib.parse import urlparse
 from pathlib import Path
-from typing import TYPE_CHECKING, ClassVar, List, Union, Optional, Any, Dict
+from typing import TYPE_CHECKING, List, Union, Optional, Any, Dict
 
 import numpy as np
 import pyarrow as pa
@@ -51,7 +52,6 @@ class JinaEmbeddings(EmbeddingFunction):
 
     name: str = "jina-clip-v1"
     api_key: Optional[str] = None
-    _session: ClassVar = None
 
     def ndims(self):
         # TODO: fix hardcoding
@@ -206,8 +206,7 @@ class JinaEmbeddings(EmbeddingFunction):
         texts: list[str] or np.ndarray (of str)
             The texts to embed
         """
-        self._init_client()
-        resp = JinaEmbeddings._session.post(  # type: ignore
+        resp = self._session.post(
             API_URL, json={"input": input, "model": self.name}
         ).json()
         if "data" not in resp:
@@ -220,14 +219,15 @@ class JinaEmbeddings(EmbeddingFunction):
 
         return [result["embedding"] for result in sorted_embeddings]
 
-    def _init_client(self):
+    @cached_property
+    def _session(self):
         import requests
 
-        if JinaEmbeddings._session is None:
-            if self.api_key is None and os.environ.get("JINA_API_KEY") is None:
-                api_key_not_found_help("jina")
-            api_key = self.api_key or os.environ.get("JINA_API_KEY")
-            JinaEmbeddings._session = requests.Session()
-            JinaEmbeddings._session.headers.update(
-                {"Authorization": f"Bearer {api_key}", "Accept-Encoding": "identity"}
-            )
+        if self.api_key is None and os.environ.get("JINA_API_KEY") is None:
+            api_key_not_found_help("jina")
+        api_key = self.api_key or os.environ.get("JINA_API_KEY")
+        session = requests.Session()
+        session.headers.update(
+            {"Authorization": f"Bearer {api_key}", "Accept-Encoding": "identity"}
+        )
+        return session

python/python/tests/test_embeddings.py

@@ -1053,3 +1053,28 @@ def test_jina_generate_image_input_dict_local_path(tmp_path):
         image_dict = JinaEmbeddings._generate_image_input_dict(image)
         assert "image" in image_dict
         assert isinstance(image_dict["image"], str) and len(image_dict["image"]) > 0
+
+
+def test_jina_embeddings_use_their_own_api_key(monkeypatch):
+    """Each JinaEmbeddings instance must send its own API key."""
+    pytest.importorskip("requests")
+    monkeypatch.delenv("JINA_API_KEY", raising=False)
+    registry = get_registry()
+    registry.set_var("jina_key_a", "key-a")
+    registry.set_var("jina_key_b", "key-b")
+    func_a = registry.get("jina").create(api_key="$var:jina_key_a")
+    func_b = registry.get("jina").create(api_key="$var:jina_key_b")
+
+    sent = []
+
+    def fake_post(session, url, json=None, **kwargs):
+        sent.append(session.headers["Authorization"])
+        response = MagicMock()
+        response.json.return_value = {"data": [{"index": 0, "embedding": [0.0]}]}
+        return response
+
+    with patch("requests.Session.post", fake_post):
+        func_a.compute_source_embeddings(["hello"])
+        func_b.compute_source_embeddings(["hello"])
+
+    assert sent == ["Bearer key-a", "Bearer key-b"]