support /message/count_tokens endpoint

routstr/payment/cost_calculation.py

@@ -36,6 +36,7 @@ class CostDataError(BaseModel):
 async def calculate_cost(
     response_data: dict, max_cost: int, session: AsyncSession
 ) -> CostData | MaxCostData | CostDataError:
+    print(response_data)
     """Calculate the cost of an API request based on token usage.
 
     Args:

routstr/upstream/base.py

@@ -42,6 +42,7 @@ from ..payment.models import (
 from ..payment.price import sats_usd_price
 from ..wallet import recieve_token, send_token
 from . import messages_dispatch
+from .count_tokens import count_tokens_locally
 from .litellm_routing import detect_litellm_prefix
 
 logger = get_logger(__name__)
@@ -2159,6 +2160,12 @@ class BaseUpstreamProvider:
         """
         path = self.normalize_request_path(path, model_obj)
 
+        if (
+            path.endswith("messages/count_tokens")
+            and not self.supports_anthropic_messages
+        ):
+            return count_tokens_locally(request_body, model_obj)
+
         if (
             path.endswith("messages")
             and not path.endswith("count_tokens")
@@ -3357,6 +3364,12 @@ class BaseUpstreamProvider:
 
         request_body = await request.body()
 
+        if (
+            path.endswith("messages/count_tokens")
+            and not self.supports_anthropic_messages
+        ):
+            return count_tokens_locally(request_body, model_obj)
+
         if (
             path.endswith("messages")
             and not path.endswith("count_tokens")

routstr/upstream/count_tokens.py

@@ -0,0 +1,108 @@
+"""Local handling of Anthropic ``/v1/messages/count_tokens`` for upstreams
+that do not natively expose the endpoint.
+
+Most non-Anthropic upstreams (OpenAI-compat, Gemini OpenAI-compat,
+OpenRouter chat-completions, generic providers) return 400/404 when asked
+to ``POST /messages/count_tokens``. Claude Code and other Anthropic SDK
+clients call this endpoint before each turn to size context windows and
+trigger compaction, so a failure breaks the whole chat.
+
+We answer locally. ``litellm.token_counter`` understands the Anthropic
+message shape and the per-model tokenizers, so we prefer it. If it raises
+(unknown model, encoding lookup failure, ...), we fall back to the
+project's own ``estimate_tokens`` heuristic, which is always defined and
+never raises.
+"""
+
+from __future__ import annotations
+
+import json
+from typing import Any
+
+import litellm
+from fastapi.responses import Response
+
+from ..core import get_logger
+from ..payment.helpers import estimate_tokens
+from ..payment.models import Model
+
+logger = get_logger(__name__)
+
+
+def _parse_request_body(request_body: bytes | None) -> dict[str, Any]:
+    if not request_body:
+        return {}
+    try:
+        parsed = json.loads(request_body)
+    except (ValueError, TypeError):
+        return {}
+    return parsed if isinstance(parsed, dict) else {}
+
+
+def _count_with_litellm(model: str, body: dict[str, Any]) -> int:
+    messages = body.get("messages")
+    if not isinstance(messages, list):
+        messages = []
+
+    system = body.get("system")
+    if isinstance(system, str) and system:
+        messages = [{"role": "system", "content": system}, *messages]
+    elif isinstance(system, list):
+        text = "".join(
+            block.get("text", "")
+            for block in system
+            if isinstance(block, dict) and block.get("type") == "text"
+        )
+        if text:
+            messages = [{"role": "system", "content": text}, *messages]
+
+    tools = body.get("tools") if isinstance(body.get("tools"), list) else None
+
+    return int(
+        litellm.token_counter(
+            model=model,
+            messages=messages,
+            tools=tools,
+        )
+    )
+
+
+def count_tokens_locally(
+    request_body: bytes | None,
+    model_obj: Model | None,
+) -> Response:
+    """Return an Anthropic-compatible count_tokens response without
+    touching the upstream. Always returns 200; never raises."""
+    body = _parse_request_body(request_body)
+
+    model_name = ""
+    if model_obj is not None:
+        model_name = model_obj.forwarded_model_id or model_obj.id or ""
+    if not model_name:
+        body_model = body.get("model")
+        if isinstance(body_model, str):
+            model_name = body_model
+
+    input_tokens: int
+    try:
+        input_tokens = _count_with_litellm(model_name, body)
+    except Exception as exc:
+        messages = body.get("messages")
+        fallback_messages = messages if isinstance(messages, list) else []
+        input_tokens = estimate_tokens(fallback_messages)
+        logger.debug(
+            "litellm token_counter failed; using local estimator",
+            extra={
+                "model": model_name,
+                "error": str(exc),
+                "error_type": type(exc).__name__,
+                "estimated_tokens": input_tokens,
+            },
+        )
+
+    payload = {"input_tokens": max(0, int(input_tokens))}
+    return Response(
+        content=json.dumps(payload).encode(),
+        status_code=200,
+        media_type="application/json",
+    )

tests/unit/test_count_tokens_local.py

@@ -0,0 +1,177 @@
+"""Unit tests for the local count_tokens shim.
+
+The shim runs whenever an upstream that does not support Anthropic's
+``/v1/messages`` endpoint is asked for a token count. It must always
+return a 200 JSON ``{"input_tokens": N}`` response and must never raise.
+"""
+
+from __future__ import annotations
+
+import json
+from typing import Any
+from unittest.mock import patch
+
+from routstr.payment.models import Architecture, Model, Pricing
+from routstr.upstream import count_tokens as count_tokens_module
+from routstr.upstream.count_tokens import count_tokens_locally
+
+
+def _make_model(model_id: str = "anthropic/claude-3-5-sonnet") -> Model:
+    pricing = Pricing(prompt=0.000003, completion=0.000015)
+    architecture = Architecture(
+        modality="text",
+        input_modalities=["text"],
+        output_modalities=["text"],
+        tokenizer="cl100k_base",
+        instruct_type=None,
+    )
+    return Model(
+        id=model_id,
+        name=model_id,
+        created=0,
+        description="",
+        context_length=200_000,
+        architecture=architecture,
+        pricing=pricing,
+    )
+
+
+def _body(payload: dict[str, Any]) -> bytes:
+    return json.dumps(payload).encode()
+
+
+def _read_payload(response: Any) -> dict[str, Any]:
+    body = response.body if isinstance(response.body, bytes) else bytes(response.body)
+    return json.loads(body.decode())
+
+
+def test_returns_input_tokens_for_simple_messages() -> None:
+    model = _make_model()
+    request_body = _body(
+        {
+            "model": model.id,
+            "messages": [{"role": "user", "content": "hello world"}],
+        }
+    )
+
+    response = count_tokens_locally(request_body, model)
+
+    assert response.status_code == 200
+    assert response.media_type == "application/json"
+    payload = _read_payload(response)
+    assert "input_tokens" in payload
+    assert isinstance(payload["input_tokens"], int)
+    assert payload["input_tokens"] >= 0
+
+
+def test_falls_back_to_estimator_when_litellm_raises() -> None:
+    model = _make_model()
+    request_body = _body(
+        {
+            "model": model.id,
+            "messages": [{"role": "user", "content": "this is a longer message"}],
+        }
+    )
+
+    with patch.object(
+        count_tokens_module,
+        "_count_with_litellm",
+        side_effect=RuntimeError("boom"),
+    ):
+        response = count_tokens_locally(request_body, model)
+
+    assert response.status_code == 200
+    payload = _read_payload(response)
+    assert payload["input_tokens"] >= 1
+
+
+def test_handles_missing_model_object() -> None:
+    request_body = _body(
+        {
+            "model": "anthropic/claude-3-5-sonnet",
+            "messages": [{"role": "user", "content": "hi"}],
+        }
+    )
+
+    response = count_tokens_locally(request_body, None)
+
+    assert response.status_code == 200
+    payload = _read_payload(response)
+    assert payload["input_tokens"] >= 0
+
+
+def test_handles_empty_request_body() -> None:
+    response = count_tokens_locally(b"", _make_model())
+
+    assert response.status_code == 200
+    payload = _read_payload(response)
+    assert payload["input_tokens"] >= 0
+
+
+def test_handles_malformed_json() -> None:
+    response = count_tokens_locally(b"not-json", _make_model())
+
+    assert response.status_code == 200
+    payload = _read_payload(response)
+    assert payload["input_tokens"] >= 0
+
+
+def test_includes_system_prompt_in_count() -> None:
+    model = _make_model()
+    short = _body(
+        {
+            "model": model.id,
+            "messages": [{"role": "user", "content": "hi"}],
+        }
+    )
+    with_system = _body(
+        {
+            "model": model.id,
+            "system": "You are a helpful assistant with a long preamble " * 10,
+            "messages": [{"role": "user", "content": "hi"}],
+        }
+    )
+
+    short_count = _read_payload(count_tokens_locally(short, model))["input_tokens"]
+    long_count = _read_payload(count_tokens_locally(with_system, model))["input_tokens"]
+
+    assert long_count > short_count
+
+
+def test_supports_anthropic_system_block_list() -> None:
+    model = _make_model()
+    request_body = _body(
+        {
+            "model": model.id,
+            "system": [{"type": "text", "text": "be terse" * 50}],
+            "messages": [{"role": "user", "content": "ok"}],
+        }
+    )
+
+    response = count_tokens_locally(request_body, model)
+
+    payload = _read_payload(response)
+    assert payload["input_tokens"] > 0
+
+
+def test_uses_forwarded_model_id_when_present() -> None:
+    model = _make_model("anthropic/claude-3-5-sonnet")
+    model.forwarded_model_id = "claude-3-5-sonnet-20241022"
+    request_body = _body(
+        {
+            "model": "ignored",
+            "messages": [{"role": "user", "content": "hi"}],
+        }
+    )
+
+    captured: dict[str, Any] = {}
+
+    def _capture(model_name: str, body: dict[str, Any]) -> int:
+        captured["model"] = model_name
+        return 7
+
+    with patch.object(count_tokens_module, "_count_with_litellm", side_effect=_capture):
+        response = count_tokens_locally(request_body, model)
+
+    assert captured["model"] == "claude-3-5-sonnet-20241022"
+    assert _read_payload(response)["input_tokens"] == 7

tests/unit/test_messages_litellm_dispatch.py

@@ -908,7 +908,7 @@ async def test_forward_request_skips_litellm_when_provider_supports_messages() -
 
 
 @pytest.mark.asyncio
-async def test_forward_request_skips_litellm_for_count_tokens() -> None:
+async def test_forward_request_handles_count_tokens_locally() -> None:
     provider = _make_provider()
     key = _make_key()
     model = _make_model()
@@ -923,19 +923,25 @@ async def test_forward_request_skips_litellm_for_count_tokens() -> None:
         with patch.object(
             provider,
             "prepare_request_body",
-            side_effect=RuntimeError("stop here"),
+            side_effect=AssertionError("upstream should not be called"),
         ):
-            with pytest.raises(RuntimeError, match="stop here"):
+            response = await provider.forward_request(
-                await provider.forward_request(
+                request=request,
-                    request=request,
+                path="messages/count_tokens",
-                    path="messages/count_tokens",
+                headers={},
-                    headers={},
+                request_body=_anthropic_request_body(),
-                    request_body=_anthropic_request_body(),
+                key=key,
-                    key=key,
+                max_cost_for_model=10_000,
-                    max_cost_for_model=10_000,
+                session=session,
-                    session=session,
+                model_obj=model,
-                    model_obj=model,
+            )
-                )
+
+    assert response.status_code == 200
+    body = response.body if isinstance(response.body, bytes) else bytes(response.body)
+    payload = json.loads(body.decode())
+    assert "input_tokens" in payload
+    assert isinstance(payload["input_tokens"], int)
+    assert payload["input_tokens"] >= 0
 
 
 # ---------------------------------------------------------------------------
@@ -1010,7 +1016,7 @@ async def test_forward_x_cashu_request_skips_litellm_when_native_messages() -> N
 
 
 @pytest.mark.asyncio
-async def test_forward_x_cashu_request_skips_litellm_for_count_tokens() -> None:
+async def test_forward_x_cashu_request_handles_count_tokens_locally() -> None:
     provider = _make_provider()
     model = _make_model()
     request = _make_request()
@@ -1024,18 +1030,24 @@ async def test_forward_x_cashu_request_skips_litellm_for_count_tokens() -> None:
         with patch.object(
             provider,
             "prepare_request_body",
-            side_effect=RuntimeError("stop here"),
+            side_effect=AssertionError("upstream should not be called"),
         ):
-            with pytest.raises(RuntimeError, match="stop here"):
+            response = await provider.forward_x_cashu_request(
-                await provider.forward_x_cashu_request(
+                request=request,
-                    request=request,
+                path="v1/messages/count_tokens",
-                    path="v1/messages/count_tokens",
+                headers={},
-                    headers={},
+                amount=5_000,
-                    amount=5_000,
+                unit="sat",
-                    unit="sat",
+                max_cost_for_model=10_000,
-                    max_cost_for_model=10_000,
+                model_obj=model,
-                    model_obj=model,
+                mint="https://mint",
-                )
+                payment_token_hash="h",
+            )
+
+    assert response.status_code == 200
+    body = response.body if isinstance(response.body, bytes) else bytes(response.body)
+    payload = json.loads(body.decode())
+    assert "input_tokens" in payload
 
 
 # ---------------------------------------------------------------------------