From 93884aae1e81b17914ce8415626ebe7ed8995109 Mon Sep 17 00:00:00 2001
From: vitali87 <eheva87@gmail.com>
Date: Sun, 30 Aug 2026 15:10:27 +0100
Subject: [PATCH] fix: only warn about truncation when the stop reason is
 max_tokens

Every non-tool_use stop reason was logged as 'LLM output truncated',
mislabelling end_turn/stop_sequence responses that carried a complete
tool block.
---
 pr_split/logs.py           |  1 +
 pr_split/planner/client.py |  5 ++++-
 tests/test_client.py       | 19 +++++++++++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/pr_split/logs.py b/pr_split/logs.py
index 3f61cd4..7ae7350 100644
--- a/pr_split/logs.py
+++ b/pr_split/logs.py
@@ -41,6 +41,7 @@
     "LLM output truncated (stop_reason: {stop_reason}), keys in partial output: {keys}"
 )
 LLM_OUTPUT_INCOMPLETE = "LLM output incomplete (status: {status}, reason: {reason})"
+LLM_UNEXPECTED_STOP = "LLM stopped with stop_reason={stop_reason} (keys in tool input: {keys})"
 CHUNK_RETRY = "Chunk {index}/{total} failed (attempt {attempt}), retrying: {error}"
 INVALID_HUNK_INDEX = (
     "Group '{group}': invalid hunk index {index} for {file} (max: {max}), skipping"
diff --git a/pr_split/planner/client.py b/pr_split/planner/client.py
index ed02b96..738e91d 100644
--- a/pr_split/planner/client.py
+++ b/pr_split/planner/client.py
@@ -142,9 +142,12 @@ def _call_anthropic(system: str, user: str, *, settings: Settings) -> RawToolOut
             if isinstance(block, BetaToolUseBlock) and isinstance(block.input, dict):
                 keys = list(block.input.keys())
                 break
-        logger.warning(logs.LLM_OUTPUT_TRUNCATED.format(stop_reason=stop_reason, keys=keys))
         if stop_reason == "max_tokens":
+            logger.warning(logs.LLM_OUTPUT_TRUNCATED.format(stop_reason=stop_reason, keys=keys))
             raise LLMError(ErrorMsg.LLM_OUTPUT_TRUNCATED(detail=f"stop_reason={stop_reason}"))
+        # Any other stop reason is not a truncation; if a tool block is
+        # present the plan is complete, otherwise the loop below reports it.
+        logger.debug(logs.LLM_UNEXPECTED_STOP.format(stop_reason=stop_reason, keys=keys))
     for block in response.content:
         if isinstance(block, BetaToolUseBlock) and block.name == SPLIT_TOOL_NAME:
             return RawToolOutput(groups=_extract_raw_output(block.input))
diff --git a/tests/test_client.py b/tests/test_client.py
index 36e13be..9d9be1a 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -1064,3 +1064,22 @@ def test_failed_status_falls_back_to_error_code(self, mock_cls: MagicMock) -> No
         )
         with pytest.raises(LLMError, match="response failed: rate_limit_exceeded"):
             _call_openai("sys", "usr", settings=_make_settings(Provider.OPENAI))
+
+
+class TestTruncationWarningScope:
+    @patch("pr_split.planner.client.logger")
+    @patch("pr_split.planner.client.anthropic.Anthropic")
+    def test_end_turn_with_tool_block_does_not_warn_truncated(
+        self, mock_cls: MagicMock, mock_logger: MagicMock
+    ) -> None:
+        from anthropic.types.beta import BetaToolUseBlock
+
+        block = BetaToolUseBlock(
+            id="tu_1", type="tool_use", name=SPLIT_TOOL_NAME, input={"groups": _SAMPLE_RAW_GROUPS}
+        )
+        mock_cls.return_value.beta.messages.create.return_value = SimpleNamespace(
+            stop_reason="end_turn", content=[block]
+        )
+        result = _call_anthropic("sys", "usr", settings=_make_settings(Provider.ANTHROPIC))
+        assert result["groups"] == _SAMPLE_RAW_GROUPS
+        assert not any("truncated" in str(c.args[0]) for c in mock_logger.warning.call_args_list)