feat: block direct MCP imports and unsanctioned keychain access (Closes #558)

Require a sanctioned MCP daemon (or pytest) before get_auth_header and
keychain credential fill so raw shell imports cannot bypass preflight gates.

tests/test_mcp_daemon_guard.py

@@ -0,0 +1,67 @@
+"""Tests for sanctioned MCP daemon guards (#558)."""
+
+from __future__ import annotations
+
+import os
+import unittest
+from unittest.mock import patch
+
+import mcp_daemon_guard
+import gitea_auth
+
+
+class TestMcpDaemonGuard(unittest.TestCase):
+    def test_unsanctioned_blocks_mutation_runtime(self):
+        env = {k: v for k, v in os.environ.items() if k not in {
+            mcp_daemon_guard.SANCTIONED_DAEMON_ENV,
+            mcp_daemon_guard.ALLOW_DIRECT_IMPORT_ENV,
+            "PYTEST_CURRENT_TEST",
+        }}
+        with patch.dict(os.environ, env, clear=True):
+            with self.assertRaises(mcp_daemon_guard.UnsanctionedRuntimeError):
+                mcp_daemon_guard.assert_sanctioned_mutation_runtime("test")
+
+    def test_pytest_allows_runtime(self):
+        # Running under pytest already sets PYTEST_CURRENT_TEST.
+        mcp_daemon_guard.assert_sanctioned_mutation_runtime("pytest")
+
+    def test_mark_sanctioned_allows(self):
+        env = {k: v for k, v in os.environ.items() if k != "PYTEST_CURRENT_TEST"}
+        env[mcp_daemon_guard.SANCTIONED_DAEMON_ENV] = "1"
+        with patch.dict(os.environ, env, clear=True):
+            mcp_daemon_guard.assert_sanctioned_mutation_runtime("daemon")
+
+    def test_keychain_blocked_without_sanction(self):
+        env = {
+            k: v
+            for k, v in os.environ.items()
+            if k
+            not in {
+                mcp_daemon_guard.SANCTIONED_DAEMON_ENV,
+                mcp_daemon_guard.ALLOW_DIRECT_IMPORT_ENV,
+                mcp_daemon_guard.ALLOW_KEYCHAIN_CLI_ENV,
+                "PYTEST_CURRENT_TEST",
+            }
+        }
+        with patch.dict(os.environ, env, clear=True):
+            with self.assertRaises(mcp_daemon_guard.UnsanctionedRuntimeError):
+                mcp_daemon_guard.assert_keychain_access_allowed()
+
+    def test_get_auth_header_blocked_when_unsanctioned(self):
+        env = {
+            k: v
+            for k, v in os.environ.items()
+            if k
+            not in {
+                mcp_daemon_guard.SANCTIONED_DAEMON_ENV,
+                mcp_daemon_guard.ALLOW_DIRECT_IMPORT_ENV,
+                "PYTEST_CURRENT_TEST",
+            }
+        }
+        with patch.dict(os.environ, env, clear=True):
+            with self.assertRaises(mcp_daemon_guard.UnsanctionedRuntimeError):
+                gitea_auth.get_auth_header("gitea.prgs.cc")
+
+
+if __name__ == "__main__":
+    unittest.main()