feat: persist MCP workflow proof and decision lock across daemons (Closes #559)

Share review-workflow-load and review-decision-lock state across MCP
daemon process pools via a user-private durable store keyed by profile
identity (not host-global /tmp), with TTL and fail-closed profile checks.

tests/test_mcp_session_state.py

@@ -0,0 +1,207 @@
+"""Tests for durable MCP session state shared across daemon processes (#559)."""
+
+from __future__ import annotations
+
+import os
+import tempfile
+import unittest
+from pathlib import Path
+from unittest.mock import patch
+
+sys_path_root = str(Path(__file__).resolve().parent.parent)
+import sys
+
+if sys_path_root not in sys.path:
+    sys.path.insert(0, sys_path_root)
+
+import mcp_session_state
+import review_workflow_load
+import mcp_server
+
+
+class TestMcpSessionStateStore(unittest.TestCase):
+    def setUp(self):
+        self._tmpdir = tempfile.TemporaryDirectory()
+        self.state_dir = self._tmpdir.name
+        self._env = patch.dict(
+            os.environ,
+            {
+                mcp_session_state.STATE_DIR_ENV: self.state_dir,
+                mcp_session_state.SESSION_PROFILE_LOCK_ENV: "prgs-reviewer",
+                "GITEA_MCP_PROFILE": "prgs-reviewer",
+            },
+            clear=False,
+        )
+        self._env.start()
+
+    def tearDown(self):
+        self._env.stop()
+        self._tmpdir.cleanup()
+
+    def test_round_trip_same_identity(self):
+        saved = mcp_session_state.save_state(
+            kind=mcp_session_state.KIND_WORKFLOW_LOAD,
+            payload={"loaded": True, "workflow_hash": "abc123def456"},
+            remote="prgs",
+            org="Scaled-Tech-Consulting",
+            repo="Gitea-Tools",
+        )
+        self.assertIsNotNone(saved)
+        self.assertEqual(saved["workflow_hash"], "abc123def456")
+        self.assertIn("recorded_at", saved)
+
+        loaded = mcp_session_state.load_state(
+            kind=mcp_session_state.KIND_WORKFLOW_LOAD,
+            remote="prgs",
+            org="Scaled-Tech-Consulting",
+            repo="Gitea-Tools",
+        )
+        self.assertIsNotNone(loaded)
+        self.assertEqual(loaded["workflow_hash"], "abc123def456")
+        self.assertEqual(loaded["profile_identity"], "prgs-reviewer")
+
+    def test_profile_mismatch_returns_none(self):
+        mcp_session_state.save_state(
+            kind=mcp_session_state.KIND_DECISION_LOCK,
+            payload={"final_review_decision_ready": True, "remote": "prgs"},
+            remote="prgs",
+        )
+        with patch.dict(
+            os.environ,
+            {mcp_session_state.SESSION_PROFILE_LOCK_ENV: "prgs-author"},
+            clear=False,
+        ):
+            loaded = mcp_session_state.load_state(
+                kind=mcp_session_state.KIND_DECISION_LOCK,
+                remote="prgs",
+            )
+        self.assertIsNone(loaded)
+
+    def test_clear_removes_file(self):
+        mcp_session_state.save_state(
+            kind=mcp_session_state.KIND_WORKFLOW_LOAD,
+            payload={"loaded": True},
+            remote="prgs",
+        )
+        path = mcp_session_state.state_file_path(
+            kind=mcp_session_state.KIND_WORKFLOW_LOAD,
+            remote="prgs",
+            profile_identity="prgs-reviewer",
+            state_dir=self.state_dir,
+        )
+        self.assertTrue(os.path.exists(path))
+        mcp_session_state.clear_state(
+            kind=mcp_session_state.KIND_WORKFLOW_LOAD,
+            remote="prgs",
+            profile_identity="prgs-reviewer",
+        )
+        self.assertFalse(os.path.exists(path))
+
+    def test_files_are_private_mode(self):
+        mcp_session_state.save_state(
+            kind=mcp_session_state.KIND_WORKFLOW_LOAD,
+            payload={"loaded": True},
+            remote="prgs",
+        )
+        path = mcp_session_state.state_file_path(
+            kind=mcp_session_state.KIND_WORKFLOW_LOAD,
+            remote="prgs",
+            profile_identity="prgs-reviewer",
+            state_dir=self.state_dir,
+        )
+        mode = os.stat(path).st_mode & 0o777
+        self.assertEqual(mode, 0o600)
+
+
+class TestWorkflowLoadCrossProcess(unittest.TestCase):
+    def setUp(self):
+        self._tmpdir = tempfile.TemporaryDirectory()
+        self._env = patch.dict(
+            os.environ,
+            {
+                mcp_session_state.STATE_DIR_ENV: self._tmpdir.name,
+                mcp_session_state.SESSION_PROFILE_LOCK_ENV: "prgs-reviewer",
+                "GITEA_MCP_PROFILE": "prgs-reviewer",
+                "GITEA_MCP_REMOTE": "prgs",
+            },
+            clear=False,
+        )
+        self._env.start()
+        review_workflow_load.clear_review_workflow_load()
+
+    def tearDown(self):
+        review_workflow_load.clear_review_workflow_load()
+        self._env.stop()
+        self._tmpdir.cleanup()
+
+    def test_different_pid_same_profile_accepted(self):
+        root = str(Path(__file__).resolve().parent.parent)
+        recorded = review_workflow_load.record_review_workflow_load(root)
+        self.assertTrue(recorded["loaded"])
+
+        # Simulate another daemon process: clear memory, keep durable file,
+        # and change apparent PID identity only (profile remains the same).
+        review_workflow_load._REVIEW_WORKFLOW_LOAD = None
+        status = review_workflow_load.workflow_load_status(root)
+        self.assertTrue(status["workflow_load_proof_present"])
+        self.assertTrue(
+            status["workflow_load_valid"],
+            msg=status.get("reasons"),
+        )
+
+    def test_profile_mismatch_blocks(self):
+        root = str(Path(__file__).resolve().parent.parent)
+        review_workflow_load.record_review_workflow_load(root)
+        review_workflow_load._REVIEW_WORKFLOW_LOAD = None
+        with patch.dict(
+            os.environ,
+            {mcp_session_state.SESSION_PROFILE_LOCK_ENV: "prgs-author"},
+            clear=False,
+        ):
+            # Durable load uses active identity; mismatched profile key misses.
+            status = review_workflow_load.workflow_load_status(root)
+        self.assertFalse(status["workflow_load_proof_present"])
+
+
+class TestDecisionLockCrossProcess(unittest.TestCase):
+    def setUp(self):
+        self._tmpdir = tempfile.TemporaryDirectory()
+        self._env = patch.dict(
+            os.environ,
+            {
+                mcp_session_state.STATE_DIR_ENV: self._tmpdir.name,
+                mcp_session_state.SESSION_PROFILE_LOCK_ENV: "prgs-reviewer",
+            },
+            clear=False,
+        )
+        self._env.start()
+        mcp_server._save_review_decision_lock(None)
+        review_workflow_load.clear_review_workflow_load()
+
+    def tearDown(self):
+        mcp_server._save_review_decision_lock(None)
+        review_workflow_load.clear_review_workflow_load()
+        self._env.stop()
+        self._tmpdir.cleanup()
+
+    def test_decision_lock_survives_memory_clear(self):
+        with patch.object(mcp_server, "get_profile", return_value={
+            "profile_name": "prgs-reviewer",
+        }):
+            mcp_server.init_review_decision_lock("prgs", "review_pr", force=True)
+            lock = mcp_server._load_review_decision_lock()
+            self.assertIsNotNone(lock)
+            self.assertEqual(lock["remote"], "prgs")
+            self.assertFalse(lock["final_review_decision_ready"])
+
+            # New process: memory empty, durable state remains.
+            mcp_server._REVIEW_DECISION_LOCK = None
+            restored = mcp_server._load_review_decision_lock()
+            self.assertIsNotNone(restored)
+            self.assertEqual(restored["remote"], "prgs")
+            reasons = mcp_server._review_decision_session_reasons(restored)
+            self.assertEqual(reasons, [])
+
+
+if __name__ == "__main__":
+    unittest.main()