Tests: Reorganize test suite into functional subdirectories

- Categorized scripts into tests/unit/, tests/integration/, tests/e2e/, and tests/tools/.
- Adopted consistent naming prefixes (test_unit_*, test_int_*, test_e2e_*, tool_*).
- Renamed conftest_mock.py to mock_config_helper.py for clarity.
- Updated test_int_boot_diagnosis.py with sys.path setup for root-level execution.

tests/unit/test_unit_payload_sanitization.py

@@ -0,0 +1,104 @@
+import sys
+import os
+from unittest.mock import MagicMock
+
+# --- Environment Setup ---
+sys.modules['redis'] = MagicMock()
+sys.modules['sqlalchemy'] = MagicMock()
+sys.modules['app.config'] = MagicMock()
+sys.modules['html2text'] = MagicMock()
+sys.modules['app.log'] = MagicMock()
+sys.modules['app.lib_general'] = MagicMock()
+
+# Mock app.db_sql
+mock_db_sql = MagicMock()
+# Mock ID resolution: abc -> 123
+mock_db_sql.redis_lookup_id_random.side_effect = lambda record_id_random, table_name: 123 if record_id_random == 'abc' else None
+sys.modules['app.db_sql'] = mock_db_sql
+
+# Add project root to path
+sys.path.append(os.getcwd())
+
+from app.lib_api_crud_v3 import sanitize_payload
+from pydantic import BaseModel, Field, ValidationError
+from typing import Optional, List, ClassVar
+
+class MockModel(BaseModel):
+    id: Optional[int]
+    name: str = Field(None, min_length=3)
+    account_id: Optional[int]
+    
+    fields_to_exclude_from_db: ClassVar[List[str]] = ['computed_field']
+
+def test_permissive_update():
+    print("--- Testing Permissive Update (ignore_extra=True) ---")
+    payload = {
+        "name": "Test",
+        "extra_field": "Should be removed",
+        "computed_field": "Should be removed"
+    }
+    sanitize_payload(payload, MockModel, ignore_extra=True)
+    print(f"Sanitized Payload: {payload}")
+    
+    assert "extra_field" not in payload
+    assert "computed_field" not in payload
+    assert payload["name"] == "Test"
+    print("✅ Permissive update stripping works.")
+
+def test_strict_update():
+    print("\n--- Testing Strict Update (ignore_extra=False) ---")
+    payload = {
+        "name": "Test",
+        "extra_field": "Should be removed",
+        "computed_field": "Should be removed"
+    }
+    sanitize_payload(payload, MockModel, ignore_extra=False)
+    print(f"Sanitized Payload: {payload}")
+    
+    assert "extra_field" in payload
+    assert "computed_field" not in payload
+    print("✅ Strict update correctly preserves unknown fields (waiting for DB error) but strips excluded fields.")
+
+def test_id_resolution():
+    print("\n--- Testing ID Resolution ---")
+    payload = {
+        "name": "Test",
+        "account_id_random": "abc"
+    }
+    sanitize_payload(payload, MockModel)
+    print(f"Sanitized Payload: {payload}")
+    
+    assert payload.get("account_id") == 123
+    assert "account_id_random" not in payload
+    print("✅ ID resolution (account_id_random -> account_id) works.")
+
+def test_structured_validation_errors():
+    print("\n--- Testing Structured Validation Errors ---")
+    payload = {
+        "name": "a" # Too short
+    }
+    try:
+        MockModel(**payload)
+    except ValidationError as e:
+        structured_errors = {err['loc'][-1]: err['msg'] for err in e.errors()}
+        print(f"Structured Errors: {structured_errors}")
+        assert "name" in structured_errors
+        # Pydantic 1.x error message
+        assert "at least 3 characters" in structured_errors["name"]
+        print("✅ Structured validation errors work.")
+
+if __name__ == "__main__":
+    try:
+        test_permissive_update()
+        test_strict_update()
+        test_id_resolution()
+        test_structured_validation_errors()
+        print("\n🎉 All local logic tests passed!")
+    except AssertionError as e:
+        print(f"\n❌ Test failed: {e}")
+        sys.exit(1)
+    except Exception as e:
+        print(f"\n💥 An error occurred: {e}")
+        import traceback
+        traceback.print_exc()
+        sys.exit(1)