diff --git a/tests/conftest.py b/tests/conftest.py
index 433ca9a..18be2f3 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -3,6 +3,26 @@
 
 import pytest
 
+
+@pytest.fixture(autouse=True)
+def _no_ambient_operator_tokens(monkeypatch):
+    """Never let a developer's real envs.json reach a test process.
+
+    `adclaw/__init__.py` calls `load_envs_into_environ()` at import time, so
+    whatever is saved in Settings > Environments on this machine becomes
+    ambient environment for every test in the suite — not just the ones
+    that opted in. Most campaign tests deliberately exercise the
+    *unauthenticated* path (MASKANX_OPERATOR_TOKENS unset), so once a real
+    operator token is configured for actual use, require_operator starts
+    demanding a header those tests never send, and they fail with 401
+    instead of the status the test is actually about. 28 tests broke this
+    way the first time a real token was set.
+
+    A test that wants a token still gets one: its own monkeypatch.setenv
+    runs after this fixture in the same test and overrides it.
+    """
+    monkeypatch.delenv("MASKANX_OPERATOR_TOKENS", raising=False)
+
 from adclaw.memory_agent.embeddings import FakeEmbeddingPipeline
 from adclaw.memory_agent.models import AOMConfig
 from adclaw.memory_agent.store import MemoryStore