diff --git a/tests/test_autofix_validation.py b/tests/test_autofix_validation.py
new file mode 100644
index 00000000..d81dfdcd
--- /dev/null
+++ b/tests/test_autofix_validation.py
@@ -0,0 +1,162 @@
+"""Test file with intentional issues to validate autofix system.
+
+This file contains:
+1. Black formatting violations
+2. Ruff lint errors
+3. Mypy type errors
+4. Failing tests
+5. Actual useful test coverage
+
+Purpose: Validate the full autofix pipeline handles all failure modes.
+"""
+
+# --- BLACK VIOLATION: Bad formatting ---
+
+# --- RUFF VIOLATIONS ---
+# F401: unused import
+import os
+
+from adapters.base import connect_db, get_adapter
+
+# E501: line too long
+VERY_LONG_STRING_THAT_VIOLATES_LINE_LENGTH = "This is a very long string that definitely exceeds the maximum line length limit of 88 characters that ruff and black enforce by default"
+
+
+# --- MYPY TYPE ERROR ---
+def bad_type_annotation(x: int) -> str:
+    return x  # Returns int, claims str
+
+
+def missing_return_type(value):
+    """Function missing type annotations."""
+    return value * 2
+
+
+# --- BLACK VIOLATION: Inconsistent spacing ---
+def poorly_formatted_function(arg1, arg2, arg3):
+    """This function has poor formatting."""
+    result = arg1 + arg2 + arg3
+    if result > 10:
+        return result
+    else:
+        return result * 2
+
+
+class BadlyFormattedClass:
+    """Class with formatting issues."""
+
+    def __init__(self, name: str, value: int):
+        self.name = name
+        self.value = value
+
+    def compute(self, multiplier: int) -> int:
+        return self.value * multiplier
+
+
+# --- ACTUAL USEFUL COVERAGE TESTS ---
+
+
+def test_connect_db_sqlite_default():
+    """Test connect_db returns valid SQLite connection."""
+    # Clear env vars to force SQLite path
+    old_url = os.environ.pop("DB_URL", None)
+    old_path = os.environ.pop("DB_PATH", None)
+
+    try:
+        conn = connect_db(":memory:")
+        assert conn is not None
+        # Verify it's a working connection
+        cursor = conn.cursor()
+        cursor.execute("SELECT 1")
+        result = cursor.fetchone()
+        assert result == (1,)
+        conn.close()
+    finally:
+        if old_url:
+            os.environ["DB_URL"] = old_url
+        if old_path:
+            os.environ["DB_PATH"] = old_path
+
+
+def test_connect_db_with_timeout():
+    """Test connect_db accepts timeout parameter."""
+    conn = connect_db(":memory:", connect_timeout=5.0)
+    assert conn is not None
+    conn.close()
+
+
+def test_get_adapter_edgar():
+    """Test that edgar adapter can be loaded."""
+    try:
+        adapter = get_adapter("edgar")
+        assert adapter is not None
+        # Verify it has expected protocol methods
+        assert (
+            hasattr(adapter, "list_new_filings")
+            or callable(getattr(adapter, "list_new_filings", None)) is False
+        )
+    except ModuleNotFoundError:
+        # Adapter module may not exist yet
+        pass
+
+
+def test_get_adapter_invalid():
+    """Test get_adapter raises for unknown adapter."""
+    try:
+        get_adapter("nonexistent_adapter_xyz")
+        assert False, "Should have raised"
+    except (ModuleNotFoundError, ImportError):
+        pass  # Expected
+
+
+# --- INTENTIONALLY FAILING TESTS ---
+
+
+def test_intentional_failure_assertion():
+    """This test intentionally fails with an assertion error."""
+    expected = 42
+    actual = 41
+    assert actual == expected, f"Expected {expected} but got {actual}"
+
+
+def test_intentional_failure_exception():
+    """This test intentionally raises an exception."""
+    data = {"key": "value"}
+    # This will raise KeyError
+    result = data["nonexistent_key"]
+
+
+def test_intentional_failure_type_error():
+    """This test intentionally causes a TypeError."""
+    value = "not a number"
+    # This will raise TypeError
+    result = value + 5
+
+
+# --- RUFF VIOLATIONS: More lint issues ---
+
+
+# W293: whitespace on blank line
+def function_with_trailing_whitespace():
+    """Has trailing whitespace."""
+    x = 1
+
+    y = 2
+    return x + y
+
+
+# E711: comparison to None
+def bad_none_comparison(value):
+    if value == None:
+        return "empty"
+    return "full"
+
+
+# E712: comparison to True
+def bad_bool_comparison(flag):
+    if flag == True:
+        return "yes"
+    return "no"
+
+
+# Autofix retest - 2025-12-29T05:30:11Z