Add server side token counting to API

src/lmstudio/async_api.py

@@ -96,6 +96,7 @@
 )
 from ._kv_config import TLoadConfig, TLoadConfigDict, parse_server_config
 from ._sdk_models import (
+    EmbeddingRpcCountTokensParameter,
     EmbeddingRpcEmbedStringParameter,
     EmbeddingRpcTokenizeParameter,
     LlmApplyPromptTemplateOpts,
@@ -733,6 +734,18 @@ async def _get_context_length(self, model_specifier: AnyModelSpecifier) -> int:
         raw_model_info = await self._get_api_model_info(model_specifier)
         return int(raw_model_info.get("contextLength", -1))
 
+    async def _count_tokens(
+        self, model_specifier: AnyModelSpecifier, input: str
+    ) -> int:
+        params = EmbeddingRpcCountTokensParameter._from_api_dict(
+            {
+                "specifier": _model_spec_to_api_dict(model_specifier),
+                "inputString": input,
+            }
+        )
+        response = await self.remote_call("countTokens", params)
+        return int(response["tokenCount"])
+
     # Private helper method to allow the main API to easily accept iterables
     async def _tokenize_text(
         self, model_specifier: AnyModelSpecifier, input: str
@@ -748,7 +761,6 @@ async def _tokenize_text(
 
     # Alas, type hints don't properly support distinguishing str vs Iterable[str]:
     #     https://github.com/python/typing/issues/256
-    @sdk_public_api_async()
     async def _tokenize(
         self, model_specifier: AnyModelSpecifier, input: str | Iterable[str]
     ) -> Sequence[int] | Sequence[Sequence[int]]:
@@ -1191,6 +1203,11 @@ async def tokenize(
         """Tokenize the input string(s) using this model."""
         return await self._session._tokenize(self.identifier, input)
 
+    @sdk_public_api_async()
+    async def count_tokens(self, input: str) -> int:
+        """Report the number of tokens needed for the input string using this model."""
+        return await self._session._count_tokens(self.identifier, input)
+
     @sdk_public_api_async()
     async def get_context_length(self) -> int:
         """Get the context length of this model."""

src/lmstudio/sync_api.py

@@ -124,6 +124,7 @@
 )
 from ._kv_config import TLoadConfig, TLoadConfigDict, parse_server_config
 from ._sdk_models import (
+    EmbeddingRpcCountTokensParameter,
     EmbeddingRpcEmbedStringParameter,
     EmbeddingRpcTokenizeParameter,
     LlmApplyPromptTemplateOpts,
@@ -902,6 +903,16 @@ def _get_context_length(self, model_specifier: AnyModelSpecifier) -> int:
         raw_model_info = self._get_api_model_info(model_specifier)
         return int(raw_model_info.get("contextLength", -1))
 
+    def _count_tokens(self, model_specifier: AnyModelSpecifier, input: str) -> int:
+        params = EmbeddingRpcCountTokensParameter._from_api_dict(
+            {
+                "specifier": _model_spec_to_api_dict(model_specifier),
+                "inputString": input,
+            }
+        )
+        response = self.remote_call("countTokens", params)
+        return int(response["tokenCount"])
+
     # Private helper method to allow the main API to easily accept iterables
     def _tokenize_text(
         self, model_specifier: AnyModelSpecifier, input: str
@@ -1353,6 +1364,11 @@ def tokenize(
         """Tokenize the input string(s) using this model."""
         return self._session._tokenize(self.identifier, input)
 
+    @sdk_public_api()
+    def count_tokens(self, input: str) -> int:
+        """Report the number of tokens needed for the input string using this model."""
+        return self._session._count_tokens(self.identifier, input)
+
     @sdk_public_api()
     def get_context_length(self) -> int:
         """Get the context length of this model."""

tests/async/test_embedding_async.py

@@ -63,11 +63,15 @@ async def test_tokenize_async(model_id: str, caplog: LogCap) -> None:
 
     caplog.set_level(logging.DEBUG)
     async with AsyncClient() as client:
-        session = client.embedding
-        response = await session._tokenize(model_id, input=text)
+        model = await client.embedding.model(model_id)
+        num_tokens = await model.count_tokens(text)
+        response = await model.tokenize(text)
     logging.info(f"Tokenization response: {response}")
     assert response
     assert isinstance(response, list)
+    # Ensure token count and tokenization are consistent
+    # (embedding models add extra start/end markers during actual tokenization)
+    assert len(response) == num_tokens + 2
     # the response should be deterministic if we set constant seed
     # so we can also check the value if desired
 
@@ -80,8 +84,8 @@ async def test_tokenize_list_async(model_id: str, caplog: LogCap) -> None:
 
     caplog.set_level(logging.DEBUG)
     async with AsyncClient() as client:
-        session = client.embedding
-        response = await session._tokenize(model_id, input=text)
+        model = await client.embedding.model(model_id)
+        response = await model.tokenize(text)
     logging.info(f"Tokenization response: {response}")
     assert response
     assert isinstance(response, list)
@@ -142,6 +146,10 @@ async def test_invalid_model_request_async(caplog: LogCap) -> None:
             with pytest.raises(LMStudioModelNotFoundError) as exc_info:
                 await model.embed("Some text")
             check_sdk_error(exc_info, __file__)
+        with anyio.fail_after(30):
+            with pytest.raises(LMStudioModelNotFoundError) as exc_info:
+                await model.count_tokens("Some text")
+            check_sdk_error(exc_info, __file__)
         with anyio.fail_after(30):
             with pytest.raises(LMStudioModelNotFoundError) as exc_info:
                 await model.tokenize("Some text")

tests/async/test_llm_async.py

@@ -2,12 +2,18 @@
 
 import logging
 
+import anyio
 import pytest
 from pytest import LogCaptureFixture as LogCap
 
-from lmstudio import AsyncClient, LlmLoadModelConfig, history
+from lmstudio import (
+    AsyncClient,
+    LlmLoadModelConfig,
+    LMStudioModelNotFoundError,
+    history,
+)
 
-from ..support import EXPECTED_LLM, EXPECTED_LLM_ID
+from ..support import EXPECTED_LLM, EXPECTED_LLM_ID, check_sdk_error
 
 
 @pytest.mark.asyncio
@@ -52,10 +58,14 @@ async def test_tokenize_async(model_id: str, caplog: LogCap) -> None:
 
     caplog.set_level(logging.DEBUG)
     async with AsyncClient() as client:
-        response = await client.llm._tokenize(model_id, input=text)
+        model = await client.llm.model(model_id)
+        num_tokens = await model.count_tokens(text)
+        response = await model.tokenize(text)
     logging.info(f"Tokenization response: {response}")
     assert response
     assert isinstance(response, list)
+    # Ensure token count and tokenization are consistent
+    assert len(response) == num_tokens
 
 
 @pytest.mark.asyncio
@@ -66,7 +76,8 @@ async def test_tokenize_list_async(model_id: str, caplog: LogCap) -> None:
 
     caplog.set_level(logging.DEBUG)
     async with AsyncClient() as client:
-        response = await client.llm._tokenize(model_id, input=text)
+        model = await client.llm.model(model_id)
+        response = await model.tokenize(text)
     logging.info(f"Tokenization response: {response}")
     assert response
     assert isinstance(response, list)
@@ -109,3 +120,33 @@ async def test_get_model_info_async(model_id: str, caplog: LogCap) -> None:
         response = await client.llm.get_model_info(model_id)
     logging.info(f"Model config response: {response}")
     assert response
+
+
+@pytest.mark.asyncio
+@pytest.mark.lmstudio
+async def test_invalid_model_request_async(caplog: LogCap) -> None:
+    caplog.set_level(logging.DEBUG)
+    async with AsyncClient() as client:
+        # Deliberately create an invalid model handle
+        model = client.llm._create_handle("No such model")
+        # This should error rather than timing out,
+        # but avoid any risk of the client hanging...
+        with anyio.fail_after(30):
+            with pytest.raises(LMStudioModelNotFoundError) as exc_info:
+                await model.complete("Some text")
+            check_sdk_error(exc_info, __file__)
+        with anyio.fail_after(30):
+            with pytest.raises(LMStudioModelNotFoundError) as exc_info:
+                await model.respond("Some text")
+            check_sdk_error(exc_info, __file__)
+        with anyio.fail_after(30):
+            with pytest.raises(LMStudioModelNotFoundError) as exc_info:
+                await model.count_tokens("Some text")
+        with anyio.fail_after(30):
+            with pytest.raises(LMStudioModelNotFoundError) as exc_info:
+                await model.tokenize("Some text")
+            check_sdk_error(exc_info, __file__)
+        with anyio.fail_after(30):
+            with pytest.raises(LMStudioModelNotFoundError) as exc_info:
+                await model.get_context_length()
+            check_sdk_error(exc_info, __file__)

tests/sync/test_embedding_sync.py

@@ -67,11 +67,15 @@ def test_tokenize_sync(model_id: str, caplog: LogCap) -> None:
 
     caplog.set_level(logging.DEBUG)
     with Client() as client:
-        session = client.embedding
-        response = session._tokenize(model_id, input=text)
+        model = client.embedding.model(model_id)
+        num_tokens = model.count_tokens(text)
+        response = model.tokenize(text)
     logging.info(f"Tokenization response: {response}")
     assert response
     assert isinstance(response, list)
+    # Ensure token count and tokenization are consistent
+    # (embedding models add extra start/end markers during actual tokenization)
+    assert len(response) == num_tokens + 2
     # the response should be deterministic if we set constant seed
     # so we can also check the value if desired
 
@@ -83,8 +87,8 @@ def test_tokenize_list_sync(model_id: str, caplog: LogCap) -> None:
 
     caplog.set_level(logging.DEBUG)
     with Client() as client:
-        session = client.embedding
-        response = session._tokenize(model_id, input=text)
+        model = client.embedding.model(model_id)
+        response = model.tokenize(text)
     logging.info(f"Tokenization response: {response}")
     assert response
     assert isinstance(response, list)
@@ -141,6 +145,10 @@ def test_invalid_model_request_sync(caplog: LogCap) -> None:
             with pytest.raises(LMStudioModelNotFoundError) as exc_info:
                 model.embed("Some text")
             check_sdk_error(exc_info, __file__)
+        with nullcontext():
+            with pytest.raises(LMStudioModelNotFoundError) as exc_info:
+                model.count_tokens("Some text")
+            check_sdk_error(exc_info, __file__)
         with nullcontext():
             with pytest.raises(LMStudioModelNotFoundError) as exc_info:
                 model.tokenize("Some text")

tests/sync/test_llm_sync.py

@@ -8,13 +8,19 @@
 """Test non-inference methods on LLMs."""
 
 import logging
+from contextlib import nullcontext
 
 import pytest
 from pytest import LogCaptureFixture as LogCap
 
-from lmstudio import Client, LlmLoadModelConfig, history
+from lmstudio import (
+    Client,
+    LlmLoadModelConfig,
+    LMStudioModelNotFoundError,
+    history,
+)
 
-from ..support import EXPECTED_LLM, EXPECTED_LLM_ID
+from ..support import EXPECTED_LLM, EXPECTED_LLM_ID, check_sdk_error
 
 
 @pytest.mark.lmstudio
@@ -55,10 +61,14 @@ def test_tokenize_sync(model_id: str, caplog: LogCap) -> None:
 
     caplog.set_level(logging.DEBUG)
     with Client() as client:
-        response = client.llm._tokenize(model_id, input=text)
+        model = client.llm.model(model_id)
+        num_tokens = model.count_tokens(text)
+        response = model.tokenize(text)
     logging.info(f"Tokenization response: {response}")
     assert response
     assert isinstance(response, list)
+    # Ensure token count and tokenization are consistent
+    assert len(response) == num_tokens
 
 
 @pytest.mark.lmstudio
@@ -68,7 +78,8 @@ def test_tokenize_list_sync(model_id: str, caplog: LogCap) -> None:
 
     caplog.set_level(logging.DEBUG)
     with Client() as client:
-        response = client.llm._tokenize(model_id, input=text)
+        model = client.llm.model(model_id)
+        response = model.tokenize(text)
     logging.info(f"Tokenization response: {response}")
     assert response
     assert isinstance(response, list)
@@ -108,3 +119,32 @@ def test_get_model_info_sync(model_id: str, caplog: LogCap) -> None:
         response = client.llm.get_model_info(model_id)
     logging.info(f"Model config response: {response}")
     assert response
+
+
+@pytest.mark.lmstudio
+def test_invalid_model_request_sync(caplog: LogCap) -> None:
+    caplog.set_level(logging.DEBUG)
+    with Client() as client:
+        # Deliberately create an invalid model handle
+        model = client.llm._create_handle("No such model")
+        # This should error rather than timing out,
+        # but avoid any risk of the client hanging...
+        with nullcontext():
+            with pytest.raises(LMStudioModelNotFoundError) as exc_info:
+                model.complete("Some text")
+            check_sdk_error(exc_info, __file__)
+        with nullcontext():
+            with pytest.raises(LMStudioModelNotFoundError) as exc_info:
+                model.respond("Some text")
+            check_sdk_error(exc_info, __file__)
+        with nullcontext():
+            with pytest.raises(LMStudioModelNotFoundError) as exc_info:
+                model.count_tokens("Some text")
+        with nullcontext():
+            with pytest.raises(LMStudioModelNotFoundError) as exc_info:
+                model.tokenize("Some text")
+            check_sdk_error(exc_info, __file__)
+        with nullcontext():
+            with pytest.raises(LMStudioModelNotFoundError) as exc_info:
+                model.get_context_length()
+            check_sdk_error(exc_info, __file__)