fix: report an Anthropic token-count failure as an LLM error instead of an SDK traceback

Author: vitali87

pr_split/exceptions.py

@@ -18,6 +18,7 @@ class ErrorMsg(StrEnum):
     MERGE_CONFLICT = "Groups '{a}' and '{b}' modify overlapping regions in '{file}'"
     NO_PLAN = "No split plan found; run 'pr-split split' first"
     LLM_PARSE_ERROR = "Failed to parse LLM response: {detail}"
+    LLM_TOKEN_COUNT_FAILED = "Could not count prompt tokens with the LLM API: {detail}"
     BRANCH_CREATE_FAILED = "Failed to create branch '{branch}': {detail}"
     PR_CREATE_FAILED = "Failed to create PR for group '{group}': {detail}"
     MERGE_FAILED = "Merge of '{source}' into '{target}' failed: {detail}"

pr_split/planner/client.py

@@ -90,12 +90,18 @@ def _extract_raw_output(block_input: dict[str, object]) -> list[_RawGroup]:
 
 def _count_tokens_anthropic(system: str, user: str, *, settings: Settings) -> int:
     client = anthropic.Anthropic(api_key=settings.api_key)
-    response = client.messages.count_tokens(
-        model=settings.model,
-        system=system,
-        messages=[{"role": "user", "content": user}],
-        tools=[_ANTHROPIC_TOOL_DEF],
-    )
+    # This is the first API call of a run, so a bad key, a network blip or a
+    # rate limit surfaces here; it must be an LLMError like every other
+    # provider failure rather than an SDK traceback.
+    try:
+        response = client.messages.count_tokens(
+            model=settings.model,
+            system=system,
+            messages=[{"role": "user", "content": user}],
+            tools=[_ANTHROPIC_TOOL_DEF],
+        )
+    except anthropic.APIError as exc:
+        raise LLMError(ErrorMsg.LLM_TOKEN_COUNT_FAILED(detail=str(exc))) from exc
     return response.input_tokens
 
 

tests/test_client.py

@@ -4,6 +4,7 @@
 from types import SimpleNamespace
 from unittest.mock import MagicMock, patch
 
+import anthropic
 import pytest
 
 from pr_split.config import Settings
@@ -547,6 +548,16 @@ def test_returns_input_tokens(self, mock_cls: MagicMock) -> None:
         assert result == 42
         mock_client.messages.count_tokens.assert_called_once()
 
+    @patch("pr_split.planner.client.anthropic.Anthropic")
+    def test_api_failure_is_an_llm_error(self, mock_cls: MagicMock) -> None:
+        mock_client = mock_cls.return_value
+        mock_client.messages.count_tokens.side_effect = anthropic.APIConnectionError(
+            request=MagicMock()
+        )
+        settings = _make_settings(Provider.ANTHROPIC)
+        with pytest.raises(LLMError, match="Could not count prompt tokens"):
+            _count_tokens_anthropic("sys", "usr", settings=settings)
+
 
 # ---------------------------------------------------------------------------
 # _count_tokens_openai