feat: implement persistent audit logging for import/export operations with Prometheus metrics

tests/test_import_parsing.py

@@ -1,12 +1,14 @@
 from __future__ import annotations
 
 from io import BytesIO
+from textwrap import dedent
 
 import pandas as pd
 import pytest
 
 from services.importers import ImportResult, load_project_imports, load_scenario_imports
 from schemas.imports import ProjectImportRow, ScenarioImportRow
+from models.project import MiningOperationType
 
 
 def test_load_project_imports_from_csv() -> None:
@@ -76,3 +78,65 @@ def test_import_errors_include_row_numbers() -> None:
     assert error.row_number == 2
     assert error.field == "name"
     assert "required" in error.message
+
+
+def test_project_import_handles_missing_columns() -> None:
+    csv_content = "name\nProject Only\n"
+    stream = BytesIO(csv_content.encode("utf-8"))
+
+    result = load_project_imports(stream, "projects.csv")
+
+    assert result.rows == []
+    assert len(result.errors) == 1
+    error = result.errors[0]
+    assert error.row_number == 2
+    assert error.field == "operation_type"
+
+
+def test_project_import_rejects_invalid_operation_type() -> None:
+    csv_content = "name,operation_type\nProject X,unknown\n"
+    stream = BytesIO(csv_content.encode("utf-8"))
+
+    result = load_project_imports(stream, "projects.csv")
+
+    assert len(result.rows) == 0
+    assert len(result.errors) == 1
+    error = result.errors[0]
+    assert error.row_number == 2
+    assert error.field == "operation_type"
+
+
+def test_scenario_import_flags_invalid_dates() -> None:
+    csv_content = dedent(
+        """
+        project_name,name,status,start_date,end_date
+        Project A,Scenario Reverse,Draft,2025-12-31,2025-01-01
+        """
+    ).strip()
+    stream = BytesIO(csv_content.encode("utf-8"))
+
+    result = load_scenario_imports(stream, "scenarios.csv")
+
+    assert len(result.rows) == 0
+    assert len(result.errors) == 1
+    error = result.errors[0]
+    assert error.row_number == 2
+    assert error.field is None
+
+
+def test_scenario_import_handles_large_dataset() -> None:
+    buffer = BytesIO()
+    df = pd.DataFrame(
+        {
+            "project_name": ["Project"] * 500,
+            "name": [f"Scenario {i}" for i in range(500)],
+            "status": ["draft"] * 500,
+        }
+    )
+    df.to_csv(buffer, index=False)
+    buffer.seek(0)
+
+    result = load_scenario_imports(buffer, "bulk.csv")
+
+    assert len(result.rows) == 500
+    assert len(result.rows) == 500