diff --git a/tests/test_driver_upload.py b/tests/test_driver_upload.py
index bce9a88..ceb00a0 100644
--- a/tests/test_driver_upload.py
+++ b/tests/test_driver_upload.py
@@ -160,3 +160,99 @@ def test_unused_files_in_response(client: TestClient) -> None:
     assert resp.status_code == 200
     # Response should indicate unused files (count or the word "unused")
     assert "unused" in resp.text.lower()
+
+
+# ---------------------------------------------------------------------------
+# Regression + OOB contract tests (Wave 0 additions -- Task 1 of 09-01)
+# ---------------------------------------------------------------------------
+
+
+def _make_driver_zip_with_cat(
+    inf_content: str = SAMPLE_INF,
+    inf_name: str = "sample.inf",
+) -> bytes:
+    """Build a ZIP with an .inf and a .cat file (has_cat_file=True)."""
+    buf = io.BytesIO()
+    with zipfile.ZipFile(buf, "w", compression=zipfile.ZIP_DEFLATED) as zf:
+        zf.writestr(inf_name, inf_content.encode("utf-8"))
+        zf.writestr(inf_name.replace(".inf", ".cat"), b"fake-cat-content")
+    return buf.getvalue()
+
+
+def _make_bom_driver_zip() -> bytes:
+    """Build a ZIP with a UTF-16 LE BOM-encoded .inf (encoding edge case)."""
+    bom_inf_text = (
+        "[Version]\r\nSignature=\"$Windows NT$\"\r\nClass=Printer\r\n\r\n"
+        "[Manufacturer]\r\n%MFG%=Models,NTamd64\r\n\r\n"
+        "[Models.NTamd64]\r\n%DRIVER_NAME%=Install,{ABCD1234-0000-0000-0000-000000000001}\r\n\r\n"
+        "[Strings]\r\nMFG=\"BOM Manufacturer\"\r\nDRIVER_NAME=\"BOM LaserJet 9000\"\r\n"
+    )
+    bom_inf_bytes = b"\xff\xfe" + bom_inf_text.encode("utf-16-le")
+    buf = io.BytesIO()
+    with zipfile.ZipFile(buf, "w", compression=zipfile.ZIP_DEFLATED) as zf:
+        zf.writestr("driver.inf", bom_inf_bytes)
+        zf.writestr("driver.cat", b"fake-catalog")
+    return buf.getvalue()
+
+
+@pytest.mark.parametrize(
+    "zip_bytes_fn, label",
+    [
+        (lambda: _make_driver_zip(extra_files={"sample.cat": b"cat"}), "plain_utf8_inf"),
+        (_make_bom_driver_zip, "bom_utf16le_inf"),
+    ],
+)
+def test_upload_500_regression(client: TestClient, zip_bytes_fn, label: str) -> None:
+    """POST /drivers/upload with a valid driver ZIP MUST return 200, never 500."""
+    zip_bytes = zip_bytes_fn()
+    resp = client.post(
+        "/drivers/upload",
+        files={"file": ("driver.zip", zip_bytes, "application/zip")},
+    )
+    assert resp.status_code != 500, f"[{label}] Upload returned HTTP 500:\n{resp.text}"
+    assert resp.status_code == 200, f"[{label}] Expected 200, got {resp.status_code}:\n{resp.text}"
+
+
+def test_upload_returns_oob_when_called_from_form(client: TestClient) -> None:
+    """POST /drivers/upload with caller=printer_form must return OOB swap markup."""
+    zip_bytes = _make_driver_zip_with_cat()
+    resp = client.post(
+        "/drivers/upload",
+        files={"file": ("driver.zip", zip_bytes, "application/zip")},
+        data={"caller": "printer_form"},
+    )
+    assert resp.status_code == 200, f"Expected 200, got {resp.status_code}:\n{resp.text}"
+    assert 'hx-swap-oob="true"' in resp.text, "Response missing hx-swap-oob attribute"
+    assert 'id="printer-form-driver-select"' in resp.text, "Response missing OOB select id"
+
+
+def test_upload_oob_autoselects_new_driver(client: TestClient) -> None:
+    """POST /drivers/upload with caller=printer_form must auto-select the new driver."""
+    import re
+
+    from imptune.db.models import Driver
+
+    zip_bytes = _make_driver_zip_with_cat()
+    resp = client.post(
+        "/drivers/upload",
+        files={"file": ("driver.zip", zip_bytes, "application/zip")},
+        data={"caller": "printer_form"},
+    )
+    assert resp.status_code == 200, f"Expected 200, got {resp.status_code}:\n{resp.text}"
+    sha = hashlib.sha256(zip_bytes).hexdigest()
+    driver = Driver.get(Driver.sha256 == sha)
+    new_id = driver.id
+    assert f'value="{new_id}"' in resp.text, f"Driver id={new_id} not found in OOB response"
+    pattern = rf'<option\s+value="{new_id}"\s+selected'
+    assert re.search(pattern, resp.text), f"New driver (id={new_id}) not marked as selected"
+
+
+def test_upload_no_oob_from_standalone_drivers_page(client: TestClient) -> None:
+    """POST /drivers/upload WITHOUT caller field must NOT contain hx-swap-oob."""
+    zip_bytes = _make_driver_zip_with_cat()
+    resp = client.post(
+        "/drivers/upload",
+        files={"file": ("driver.zip", zip_bytes, "application/zip")},
+    )
+    assert resp.status_code == 200, f"Expected 200, got {resp.status_code}:\n{resp.text}"
+    assert "hx-swap-oob" not in resp.text, "Standalone upload should NOT return OOB fragments"