fix: pipeline LLM 全失败时明确报错而非静默输出空 IR - Closes #15

- step1: 所有 LLM 调用返回空 function_units 时抛出 RuntimeError
- step1: main() 在 _quick_validate 未通过时 sys.exit(1)
- step2: function_units 为空时提前报错终止
- step3: fragments 为空时提前报错终止
- test: test_step1 捕获 SystemExit, test_step2_5/step3 空数据改为 skip

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

skills/ir_generation_skill/tests/test_step1.py

@@ -376,10 +376,13 @@ def _load_si_and_doc():
     """Try to load semantic_index.json and the input document. Returns (si, doc) or (None, None)."""
     try:
         si = config.load_json(config.SEMANTIC_INDEX_JSON)
-        doc = config.load_input_document()
-        return si, doc
     except FileNotFoundError:
         return None, None
+    try:
+        doc = config.load_input_document()
+    except (FileNotFoundError, SystemExit):
+        return None, None
+    return si, doc
 
 
 def test_step1_unit_ids():

skills/ir_generation_skill/tests/test_step2_5.py

@@ -160,6 +160,8 @@ def test_step2_5_path_enumeration():
         path_data = config.load_json(config.PATH_ENUM_JSON)
     except FileNotFoundError:
         pytest.skip("path_enumeration.json not found — run step2_5_branch_coverage.py first")
+    if path_data.get("total_paths", 0) == 0:
+        pytest.skip("path_enumeration.json has 0 paths — pipeline may have failed upstream")
     errors = check_path_enumeration(path_data)
     assert not errors, f"path enumeration errors: {errors}"
 

skills/ir_generation_skill/tests/test_step3.py

@@ -235,11 +235,14 @@ import pytest  # noqa: E402
 
 
 def _load_ir_final_or_skip():
-    """Load ir_final.json or return None."""
+    """Load ir_final.json. Returns None if file missing or rules empty (failed pipeline)."""
     try:
-        return config.load_json(config.IR_FINAL_JSON)
+        data = config.load_json(config.IR_FINAL_JSON)
     except FileNotFoundError:
         return None
+    if not data.get("rules"):
+        return None  # Skip: pipeline produced empty results
+    return data
 
 
 def _load_audit_report_or_skip():