feat: enforce live-namespace block in review/merge state machine (#543 AC5)

The namespace health check (05fdcee) classified a false-ready namespace but
only returned an advisory blocks_merge_workflow flag; nothing in the merge
gate consumed it. Wire it in so a broken live namespace hard-blocks merge.

- review_merge_state_machine.assess_workflow_blockers: add live_namespace_broken
  blocker (registered-in-FastMCP but not callable-through-namespace).
- assess_state_advancement: forward **blocker_kwargs so can_approve/can_merge/
  workflow_status honor the full blocker set (also fixes latent drop of
  mcp_reconnect_failed/stale_capability_state through those paths).
- gitea_assess_review_merge_state_machine tool: accept live_namespace_broken and
  thread it through all state-machine calls.
- Tests: prove can_merge/workflow_status/tool block on live_namespace_broken even
  with every review state + pre-merge gate satisfied; bridge classify verdict.
- Docs: enforcement section wiring blocks_merge_workflow -> live_namespace_broken.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

docs/mcp-namespace-health.md

@@ -52,3 +52,25 @@ The read-only `gitea_assess_mcp_namespace_health` tool can classify probe
 evidence supplied by a client. It intentionally distinguishes
 `required_tool_registered=true` from `required_tool_callable=false`; the latter
 must block reviewer and merger workflows until the live namespace is repaired.
+
+## Enforcement in the review/merge state machine
+
+The block is not advisory. Feed the `blocks_merge_workflow` verdict from
+`gitea_assess_mcp_namespace_health` into
+`gitea_assess_review_merge_state_machine` as `live_namespace_broken`:
+
+```text
+health  = gitea_assess_mcp_namespace_health(namespace="gitea-merger", ...)
+state   = gitea_assess_review_merge_state_machine(
+              state_completion=...,
+              pre_merge_gates=...,
+              live_namespace_broken=health["blocks_merge_workflow"],
+          )
+# state["merge"]["allowed"] is False whenever the live namespace is broken,
+# even when every review state and pre-merge gate is otherwise satisfied.
+```
+
+When `live_namespace_broken=True`, `assess_workflow_blockers`,
+`can_approve`, `can_merge`, and `workflow_status` all fail closed. This is the
+guard that stops a merge from proceeding on a false-ready namespace, as in the
+PR #418 halt that motivated this work (#543).

gitea_mcp_server.py

@@ -7792,40 +7792,45 @@ def gitea_assess_review_merge_state_machine(
     pre_merge_gates: dict[str, bool] | None = None,
     infra_stop: bool = False,
     capability_blocked: bool = False,
+    live_namespace_broken: bool = False,
     recovery_handoff_text: str | None = None,
     final_report_text: str | None = None,
 ) -> dict:
-    """Read-only: assess enforced PR review/merge workflow state (#290)."""
+    """Read-only: assess enforced PR review/merge workflow state (#290).
+
+    ``live_namespace_broken`` fails review/merge closed when the live MCP
+    namespace call path is unusable even though the tool is registered in
+    FastMCP (#543 AC5). Supply the ``blocks_merge_workflow`` verdict from
+    ``gitea_assess_mcp_namespace_health``.
+    """
     completion = state_completion or {}
-    blockers = review_merge_state_machine.assess_workflow_blockers(
+    blocker_kwargs = {
-        infra_stop=infra_stop,
+        "infra_stop": infra_stop,
-        capability_blocked=capability_blocked,
+        "capability_blocked": capability_blocked,
-    )
+        "live_namespace_broken": live_namespace_broken,
+    }
+    blockers = review_merge_state_machine.assess_workflow_blockers(**blocker_kwargs)
     result = {
         "workflow": review_merge_state_machine.workflow_status(
             completion,
-            infra_stop=infra_stop,
+            **blocker_kwargs,
-            capability_blocked=capability_blocked,
         ),
         "blockers": blockers,
         "approve": review_merge_state_machine.can_approve(
             completion,
-            infra_stop=infra_stop,
+            **blocker_kwargs,
-            capability_blocked=capability_blocked,
         ),
         "merge": review_merge_state_machine.can_merge(
             completion,
             pre_merge_gates=pre_merge_gates,
-            infra_stop=infra_stop,
+            **blocker_kwargs,
-            capability_blocked=capability_blocked,
         ),
     }
     if target_state:
         result["advancement"] = review_merge_state_machine.assess_state_advancement(
             completion,
             target_state=target_state,
-            infra_stop=infra_stop,
+            **blocker_kwargs,
-            capability_blocked=capability_blocked,
         )
     if recovery_handoff_text is not None:
         result["recovery_handoff"] = (

review_merge_state_machine.py

@@ -93,8 +93,16 @@ def assess_workflow_blockers(
     capability_blocked: bool = False,
     mcp_reconnect_failed: bool = False,
     stale_capability_state: bool = False,
+    live_namespace_broken: bool = False,
 ) -> dict[str, Any]:
-    """Return hard blockers that forbid all PR queue work (#290 AC3)."""
+    """Return hard blockers that forbid all PR queue work (#290 AC3).
+
+    ``live_namespace_broken`` fails the merge/review path closed when the live
+    MCP namespace call path is unusable (e.g. ``client is closing: EOF``) even
+    though the tool is registered in FastMCP (#543 AC5). Feed it the
+    ``blocks_merge_workflow`` verdict from
+    ``mcp_namespace_health.classify_namespace_probe``.
+    """
     reasons: list[str] = []
     if infra_stop:
         reasons.append("infra_stop is active; PR selection/review/merge is forbidden")
@@ -104,6 +112,12 @@ def assess_workflow_blockers(
         reasons.append("MCP reconnect failed; stale session state cannot be reused")
     if stale_capability_state:
         reasons.append("stale MCP capability state detected after reconnect failure")
+    if live_namespace_broken:
+        reasons.append(
+            "live MCP namespace call path is broken (registered in FastMCP but "
+            "not callable through the namespace); repair the namespace before "
+            "review/merge"
+        )
     return {
         "block": bool(reasons),
         "reasons": reasons,
@@ -118,16 +132,19 @@ def assess_state_advancement(
     state_completion: dict[str, bool] | None,
     *,
     target_state: str,
-    infra_stop: bool = False,
+    **blocker_kwargs,
-    capability_blocked: bool = False,
 ) -> dict[str, Any]:
-    """Fail closed when *target_state* is requested before upstream gates pass."""
+    """Fail closed when *target_state* is requested before upstream gates pass.
+
+    Forwards every blocker flag (``infra_stop``, ``capability_blocked``,
+    ``mcp_reconnect_failed``, ``stale_capability_state``,
+    ``live_namespace_broken``) to :func:`assess_workflow_blockers` so
+    ``can_approve``/``can_merge`` honor the full blocker set, not just
+    infra_stop/capability_blocked (#543 AC5).
+    """
     completion = dict(state_completion or {})
     target = _clean(target_state).upper()
-    blockers = assess_workflow_blockers(
+    blockers = assess_workflow_blockers(**blocker_kwargs)
-        infra_stop=infra_stop,
-        capability_blocked=capability_blocked,
-    )
     reasons = list(blockers["reasons"])
 
     try:

tests/test_mcp_namespace_health.py

@@ -2,6 +2,7 @@ import unittest
 
 import gitea_mcp_server
 import mcp_namespace_health
+import review_merge_state_machine as rmsm
 
 
 class TestMcpNamespaceHealth(unittest.TestCase):
@@ -81,5 +82,74 @@ class TestMcpNamespaceHealth(unittest.TestCase):
         self.assertEqual(result["diagnostics"]["process_pid"], 9876)
 
 
+class TestLiveNamespaceBlocksMerge(unittest.TestCase):
+    """AC5: a broken live namespace must hard-block the review/merge state machine."""
+
+    def _merge_ready_completion(self):
+        # Completion through PRE_MERGE_RECHECK is the state where a clean merge
+        # is otherwise allowed (see test_merge_allowed_with_pre_merge_gates).
+        idx = rmsm.REVIEW_MERGE_STATES.index("PRE_MERGE_RECHECK")
+        return {state: True for state in rmsm.REVIEW_MERGE_STATES[: idx + 1]}
+
+    def _all_gates(self):
+        return {gate: True for gate in rmsm._PRE_MERGE_REQUIRED_GATES}
+
+    def test_assess_workflow_blockers_flags_live_namespace_broken(self):
+        clean = rmsm.assess_workflow_blockers()
+        self.assertFalse(clean["block"])
+
+        broken = rmsm.assess_workflow_blockers(live_namespace_broken=True)
+        self.assertTrue(broken["block"])
+        self.assertTrue(any("namespace" in r.lower() for r in broken["reasons"]))
+
+    def test_can_merge_blocks_even_when_all_gates_pass(self):
+        # Without the namespace blocker a fully-complete workflow can merge...
+        allowed = rmsm.can_merge(
+            self._merge_ready_completion(), pre_merge_gates=self._all_gates()
+        )
+        self.assertTrue(allowed["allowed"])
+
+        # ...but a broken live namespace overrides every satisfied gate.
+        blocked = rmsm.can_merge(
+            self._merge_ready_completion(),
+            pre_merge_gates=self._all_gates(),
+            live_namespace_broken=True,
+        )
+        self.assertTrue(blocked["block"])
+        self.assertFalse(blocked["allowed"])
+
+    def test_workflow_status_forwards_namespace_blocker(self):
+        status = rmsm.workflow_status(
+            self._merge_ready_completion(), live_namespace_broken=True
+        )
+        self.assertFalse(status["merge_allowed"])
+        self.assertFalse(status["approve_allowed"])
+
+    def test_server_tool_blocks_merge_on_live_namespace_broken(self):
+        result = gitea_mcp_server.gitea_assess_review_merge_state_machine(
+            state_completion=self._merge_ready_completion(),
+            pre_merge_gates=self._all_gates(),
+            live_namespace_broken=True,
+        )
+        self.assertTrue(result["blockers"]["block"])
+        self.assertFalse(result["merge"]["allowed"])
+
+    def test_classify_verdict_bridges_into_merge_block(self):
+        # The classify verdict is the intended feed for live_namespace_broken.
+        verdict = mcp_namespace_health.classify_namespace_probe(
+            "gitea-merger",
+            registered_tools=["gitea_whoami", "gitea_adopt_merger_pr_lease"],
+            probe_result={"success": False, "error": "client is closing: EOF"},
+            process={"pid": 555, "profile": "prgs-merger"},
+        )
+        self.assertTrue(verdict["blocks_merge_workflow"])
+        blocked = rmsm.can_merge(
+            self._merge_ready_completion(),
+            pre_merge_gates=self._all_gates(),
+            live_namespace_broken=verdict["blocks_merge_workflow"],
+        )
+        self.assertFalse(blocked["allowed"])
+
+
 if __name__ == "__main__":
     unittest.main()