diff --git a/gateway/platform_registry.py b/gateway/platform_registry.py
index f8f99cf155..cd35d032f3 100644
--- a/gateway/platform_registry.py
+++ b/gateway/platform_registry.py
@@ -120,6 +120,16 @@ class PlatformEntry:
     shared_env_prefixes: tuple = ()
 
 
+def core_ships_platform(name: str) -> bool:
+    """*name* is a platform core ships an adapter for: a static ``Platform`` member or a bundled
+    ``plugins/platforms/`` plugin. A user plugin may replace such an adapter but never mark it
+    ``trusted_inbound``: its senders are people, and that flag waives allowlists and pairing."""
+    from gateway.config import Platform
+    value = str(name or "").strip().lower()
+    return value in {Platform[member].value for member in Platform._member_names_} or (
+        value in Platform._scan_bundled_plugin_platforms()[0])
+
+
 class PlatformRegistry:
     """Central registry of platform adapters. Registrations are serialized; concurrent
     lazy lookups share an in-flight event while the loader runs outside the registry lock."""
diff --git a/hermes_cli/plugin_validate.py b/hermes_cli/plugin_validate.py
index b31f97d6fe..131e82f991 100644
--- a/hermes_cli/plugin_validate.py
+++ b/hermes_cli/plugin_validate.py
@@ -206,7 +206,7 @@ options = json.loads(sys.argv[3])
 context_methods = set(options["context_methods"])
 provider_kind = options["kind"] == "model-provider"
 
-recorded = {"tools": [], "hooks": [], "middleware": [], "commands": [], "providers": []}
+recorded = {"tools": [], "hooks": [], "middleware": [], "commands": [], "providers": [], "trusted_inbound": []}
 
 
 class RecordingContext:
@@ -229,6 +229,10 @@ class RecordingContext:
     def register_cli_command(self, name, *args, **kwargs):
         recorded["commands"].append(str(name))
 
+    def register_platform(self, name, *args, **kwargs):
+        if kwargs.get("trusted_inbound"):
+            recorded["trusted_inbound"].append(str(name))
+
     def get_config(self, key, default=None):
         # Mirrors PluginContext.get_config with no config on disk: the DEFAULT, never None —
         # plugins do `int(ctx.get_config("timeout", 180))` in register().
@@ -518,6 +522,7 @@ def validate_plugin_dir(plugin_dir: Path) -> ValidationReport:
     _check_python_dependencies(report, plugin_dir)
     recorded = _check_capabilities(report, manifest, plugin_dir)
     _check_builtin_collisions(report, manifest, recorded)
+    _check_trusted_inbound(report, recorded)
     _check_security_scan(report, plugin_dir)
     check_core_override(report, plugin_dir)
     check_desktop_surface(report, plugin_dir)
@@ -527,6 +532,17 @@ def validate_plugin_dir(plugin_dir: Path) -> ValidationReport:
     return report
 
 
+def _check_trusted_inbound(report: ValidationReport, recorded: Optional[dict]) -> None:
+    """Surface ``trusted_inbound`` platforms (their events skip user allowlists and pairing); one
+    naming a core platform fails, as the loader refuses it."""
+    from gateway.platform_registry import core_ships_platform
+    for name in (recorded or {}).get("trusted_inbound") or []:
+        if core_ships_platform(name):
+            report.add("trusted inbound", False, f"platform '{name}' ships with core; trusted_inbound is refused for it")
+        else:
+            report.add("trusted inbound", True, f"platform '{name}' is trusted_inbound: its events skip user allowlists and pairing")
+
+
 _LOADABLE_ENTRYPOINTS = ("__init__.py", "desktop/plugin.js", "plugin.json")
 
 
diff --git a/hermes_cli/plugins.py b/hermes_cli/plugins.py
index 02222185a2..4fbf7394c8 100644
--- a/hermes_cli/plugins.py
+++ b/hermes_cli/plugins.py
@@ -815,7 +815,9 @@ class PluginContext:
         it freely); an ACTIVE installer goes in ``ensure_deps_fn`` (called from ``create_adapter()`` when
         ``check_fn`` is False). Extra kwargs (``setup_fn``, ``emoji``, ``allowed_users_env``,
         ``platform_hint``, ``ensure_deps_fn``) forward to ``PlatformEntry``; unknown keys raise TypeError."""
-        from gateway.platform_registry import platform_registry, PlatformEntry
+        from gateway.platform_registry import core_ships_platform, platform_registry, PlatformEntry
+        if entry_kwargs.get("trusted_inbound") and self.manifest.source != "bundled" and core_ships_platform(name):
+            raise self._refuse(f"core platform '{name}' with trusted_inbound (it would waive allowlists and pairing)")
         entry_kwargs.setdefault("plugin_name", self.manifest.name)
         entry = PlatformEntry(
             name=name, label=label, adapter_factory=adapter_factory, check_fn=check_fn,
diff --git a/tests/gateway/test_platform_entry_plugin_seams.py b/tests/gateway/test_platform_entry_plugin_seams.py
index 4f284d86ec..ebd0145fc6 100644
--- a/tests/gateway/test_platform_entry_plugin_seams.py
+++ b/tests/gateway/test_platform_entry_plugin_seams.py
@@ -69,3 +69,19 @@ def test_display_tier_supplies_builtin_defaults_below_user_overrides(plugin_plat
 def test_platform_entry_seam_defaults_are_inert():
     entry = PlatformEntry(name="x", label="X", adapter_factory=lambda cfg: None, check_fn=lambda: True)
     assert (entry.trusted_inbound, entry.display_tier, entry.shared_env_prefixes) == (False, "", ())
+
+
+def test_user_plugin_cannot_mark_a_core_platform_trusted_inbound():
+    from hermes_cli.plugins import PluginContext, PluginManager, PluginManifest
+    ctx = PluginContext(PluginManifest(name="seamevil", key="seamevil", source="user"),
+                        PluginManager(scope_key=platform_registry.current_scope_key()))
+    with pytest.raises(ValueError, match="trusted_inbound"):
+        ctx.register_platform("telegram", "Telegram", adapter_factory=lambda cfg: None, check_fn=lambda: True,
+                              trusted_inbound=True)
+    # Control: a platform core does not ship (Home Assistant's case) may declare it.
+    try:
+        ctx.register_platform("seameventbus", "Bus", adapter_factory=lambda cfg: None, check_fn=lambda: True,
+                              trusted_inbound=True)
+        assert platform_registry.get("seameventbus").trusted_inbound is True
+    finally:
+        platform_registry.unregister("seameventbus", scope=platform_registry.current_scope_key())
diff --git a/tests/tools/test_mcp_dynamic_discovery.py b/tests/tools/test_mcp_dynamic_discovery.py
index 602bc223fc..ddea7eaf4d 100644
--- a/tests/tools/test_mcp_dynamic_discovery.py
+++ b/tests/tools/test_mcp_dynamic_discovery.py
@@ -39,9 +39,9 @@ class TestRegisterServerTools:
         """An MCP server named after a built-in toolset must not be shadowed.
 
         Regression: an MCP server registered under a built-in toolset's name
-        (originally `browser`; `browser` here) had its tools silently
-        dropped because get_toolset() returned the static definition without
-        consulting the alias registered by _register_server_tools().
+        (`browser` here) had its tools silently dropped because get_toolset()
+        returned the static definition without consulting the alias
+        registered by _register_server_tools().
         """
         from toolsets import TOOLSETS, get_toolset, resolve_toolset