Replace trajectory audit with isolated prefix scoring

tests/test_evidence.py

@@ -1,6 +1,11 @@
 """Tests for prompt-only trajectory compaction."""
 
-from swe_data_processing.evidence import compact_text, compact_trajectory
+from swe_data_processing.evidence import (
+    BOUNDARY_BLOCK_TURNS,
+    build_trajectory_blocks,
+    compact_text,
+    compact_trajectory,
+)
 
 
 def test_compact_text_preserves_short_values() -> None:
@@ -36,3 +41,33 @@ def test_compact_trajectory_prioritizes_test_observations() -> None:
     compacted, metadata = compact_trajectory(trajectory, signals)
     assert compacted[2]["content"] == long_content
     assert 3 in metadata["important_turn_ids"]
+
+
+def test_boundary_blocks_preserve_absolute_turns_without_overlap() -> None:
+    trajectory = [
+        {"turn_id": turn, "role": "assistant", "content": f"turn {turn}"}
+        for turn in range(1, BOUNDARY_BLOCK_TURNS + 3)
+    ]
+    blocks, metadata = build_trajectory_blocks(trajectory, {})
+    assert len(blocks) == 2
+    assert blocks[0]["start_turn"] == 1
+    assert blocks[0]["end_turn"] == BOUNDARY_BLOCK_TURNS
+    assert blocks[1]["start_turn"] == BOUNDARY_BLOCK_TURNS + 1
+    assert blocks[1]["end_turn"] == BOUNDARY_BLOCK_TURNS + 2
+    turn_ids = [
+        message["turn_id"] for block in blocks for message in block["messages"]
+    ]
+    assert turn_ids == list(range(1, BOUNDARY_BLOCK_TURNS + 3))
+    assert metadata["block_count"] == 2
+
+
+def test_boundary_block_keeps_immediate_tool_result_with_assistant() -> None:
+    trajectory = [
+        {"turn_id": turn, "role": "user", "content": f"turn {turn}"}
+        for turn in range(1, BOUNDARY_BLOCK_TURNS + 2)
+    ]
+    trajectory[BOUNDARY_BLOCK_TURNS - 1]["role"] = "assistant"
+    trajectory[BOUNDARY_BLOCK_TURNS]["role"] = "tool"
+    blocks, _ = build_trajectory_blocks(trajectory, {})
+    assert blocks[0]["end_turn"] == BOUNDARY_BLOCK_TURNS + 1
+    assert len(blocks) == 1