fix(mcp): a profile only adopts a shared connection whose credentials match its own config

_same_server_route compared config_fingerprint alone, which by design excludes
env/headers/auth (so the schema cache survives a token rotation). Profile B with the
same URL but different headers/env therefore adopted profile A's live connection and
called tools as A. _connection_identity = route fingerprint + env + headers + auth mode,
used by both the adopt and the stale-removal checks.

Also collapses the three writers of _server_tool_scopes to two: the adoption loop
re-implemented in mcp_tool_discovery._select_new_servers is dropped —
register_connected_into_current_scope (which runs first in register_mcp_servers) is
the single adopter, and _register_candidates records scope for freshly registered tools.

tests/gateway/test_multiplex_mcp_discovery.py

@@ -126,7 +126,8 @@ async def test_reload_mcp_reports_a_shared_server_to_a_non_owner_profile(
         get_or_create_session=MagicMock(side_effect=RuntimeError("skip transcript")),
     )
 
-    live_server = SimpleNamespace(session=object(), _config={})
+    live_server = SimpleNamespace(session=object(), _config={}, _tools=[], tool_timeout=30,
+                                  initialize_result=None, _registered_tool_names=[])
     monkeypatch.setattr(mcp_tool, "_servers", {"shared": live_server})
     monkeypatch.setattr(mcp_tool, "_server_scope_keys", {"shared": launch_scope})
     monkeypatch.setattr(mcp_tool, "_server_tool_scopes", {"shared": {launch_scope}}, raising=False)
@@ -136,7 +137,8 @@ async def test_reload_mcp_reports_a_shared_server_to_a_non_owner_profile(
     monkeypatch.setattr(mcp_tool, "_mcp_registry_scope", lambda: worker_scope)
 
     def fake_discover() -> list[str]:
-        _mcp_discovery._select_new_servers({"shared": {}})
+        from tools import mcp_tool_registration as _mcp_registration
+        _mcp_registration.register_connected_into_current_scope({"shared": {}})
         return ["mcp__shared__tool"]
 
     monkeypatch.setattr(_mcp_lifecycle, "shutdown_mcp_servers", lambda **_kwargs: None)
@@ -157,11 +159,18 @@ async def test_reload_mcp_reports_a_shared_server_to_a_non_owner_profile(
     assert mcp_tool._server_tool_scopes["shared"] == {launch_scope, worker_scope}
 
 
-def test_scope_visibility_rejects_a_foreign_server_route(
-    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+@pytest.mark.parametrize("worker_cfg", [
+    {"url": "https://worker.example/mcp"},                                   # different route
+    {"url": "https://default.example/mcp", "headers": {"Authorization": "Bearer worker"}},  # same route, other credentials
+    {"url": "https://default.example/mcp", "env": {"API_TOKEN": "worker"}},
+])
+def test_scope_visibility_rejects_a_foreign_or_differently_authenticated_route(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch, worker_cfg: dict
 ) -> None:
+    """A profile may only see a live connection whose route AND credentials match its own config;
+    otherwise it would call tools as the owning profile's identity."""
     from tools import mcp_tool
-    from tools import mcp_tool_discovery as _mcp_discovery
+    from tools import mcp_tool_registration as _mcp_registration
 
     worker_scope = hermes_home_key(tmp_path / "worker")
     launch_scope = hermes_home_key(tmp_path / "default")
@@ -169,13 +178,9 @@ def test_scope_visibility_rejects_a_foreign_server_route(
     monkeypatch.setattr(mcp_tool, "_servers", {"shared": live_server})
     monkeypatch.setattr(mcp_tool, "_server_scope_keys", {"shared": launch_scope})
     monkeypatch.setattr(mcp_tool, "_server_tool_scopes", {"shared": {launch_scope}}, raising=False)
-    monkeypatch.setattr(mcp_tool, "_server_connecting", set())
-    monkeypatch.setattr(mcp_tool, "_server_connect_errors", {})
-    monkeypatch.setattr(mcp_tool, "_lazy_server_configs", {})
     monkeypatch.setattr(mcp_tool, "_mcp_registry_scope", lambda: worker_scope)
 
-    _mcp_discovery._select_new_servers({"shared": {"url": "https://worker.example/mcp"}})
-
+    assert _mcp_registration.register_connected_into_current_scope({"shared": worker_cfg}) == 0
     assert mcp_tool._server_tool_scopes["shared"] == {launch_scope}
 
 

tools/mcp_tool_discovery.py

@@ -247,19 +247,6 @@ def _select_new_servers(servers: Dict[str, dict]) -> Dict[str, dict]:
         for srv_name in new_servers:
             _core._server_scope_keys[srv_name] = current_scope
             _core._server_connect_errors.pop(srv_name, None)
-        # A shared connection can already be owned by another profile. Record the current
-        # profile's visibility separately so its scoped reload sees the connection without
-        # moving teardown ownership away from the profile that opened it.
-        if current_scope is not None:
-            from tools.mcp_schema_cache import config_fingerprint
-            for srv_name, srv_cfg in servers.items():
-                if not _enabled(srv_cfg):
-                    continue
-                server = _core._servers.get(srv_name)
-                if (server is not None and getattr(server, "session", None) is not None
-                        and config_fingerprint(getattr(server, "_config", {}) or {})
-                        == config_fingerprint(srv_cfg)):
-                    _core._server_tool_scopes.setdefault(srv_name, set()).add(current_scope)
         # Track which servers opt-in to parallel tool calls (idempotent).
         for srv_name, srv_cfg in servers.items():
             if _parse_boolish(srv_cfg.get("supports_parallel_tool_calls", False), default=False):

tools/mcp_tool_registration.py

@@ -3,6 +3,7 @@ include/exclude filtering, trust-tier metadata capture, utility-tool selection,
 resolution and the schema-cache write-through. Both entry points (``_register_server_tools``
 live, ``_register_from_cache_sync`` lazy) build ``_Candidate`` records for ``_register_candidates``."""
 
+import json
 import logging
 import threading
 from dataclasses import dataclass
@@ -376,10 +377,22 @@ def _server_enabled(config: dict) -> bool:
     return _parse_boolish(config.get("enabled", True), default=True)
 
 
-def _same_server_route(server: Any, config: dict) -> bool:
+def _connection_identity(config: dict) -> tuple:
+    """What makes one live connection reusable for another profile: the route fingerprint PLUS
+    everything that authenticates it (``config_fingerprint`` deliberately excludes credentials so
+    the schema cache survives a token rotation). Two profiles pointing at the same URL with different
+    headers/env/auth are two identities; borrowing across them would call tools as the other user."""
     from tools.mcp_schema_cache import config_fingerprint
 
-    return config_fingerprint(getattr(server, "_config", {}) or {}) == config_fingerprint(config)
+    def _frozen(value):
+        return json.dumps(value or {}, sort_keys=True, default=str)
+
+    return (config_fingerprint(config), _frozen(config.get("env")), _frozen(config.get("headers")),
+            (config.get("auth") or "").lower().strip())
+
+
+def _same_server_route(server: Any, config: dict) -> bool:
+    return _connection_identity(getattr(server, "_config", {}) or {}) == _connection_identity(config)
 
 
 def register_connected_into_current_scope(servers: dict) -> int:
@@ -405,8 +418,6 @@ def _register_connected_into_current_scope(servers: dict) -> int:
     if scope is None:
         return 0
 
-    from tools.mcp_schema_cache import config_fingerprint
-
     with _core._lock:
         stale = []
         for name, scopes in _core._server_tool_scopes.items():
@@ -415,8 +426,7 @@ def _register_connected_into_current_scope(servers: dict) -> int:
             server = _core._servers.get(name)
             config = servers.get(name)
             if (config is None or not _server_enabled(config) or server is None
-                    or getattr(server, "session", None) is None
-                    or config_fingerprint(getattr(server, "_config", {}) or {}) != config_fingerprint(config)):
+                    or getattr(server, "session", None) is None or not _same_server_route(server, config)):
                 stale.append(name)
     for name in stale:
         _remove_server_scope(name, scope)
@@ -429,6 +439,9 @@ def _register_connected_into_current_scope(servers: dict) -> int:
             server = _core._servers.get(name)
         if server is None or getattr(server, "session", None) is None or not _same_server_route(server, config):
             continue
+        # Visibility for this profile: the owner keeps teardown, this scope sees the connection.
+        with _core._lock:
+            _core._server_tool_scopes.setdefault(name, set()).add(scope)
         if registry.get_tool_names_for_toolset(f"mcp-{name}"):
             continue
         candidates = _tool_candidates(name, server._tools, _make_tool_filter(name, config), server.tool_timeout)