fix: re-pin channel registry after deferred plugin reload

When preferSetupRuntimeForChannelPlugins is active, gateway boot performs
two plugin loads: a setup-runtime pass and a full reload after listen.
The initial pin captured the setup-entry snapshot. The deferred reload now
re-pins so getChannelPlugin() resolves against the full implementations.

src/gateway/server-runtime-state.ts

@@ -236,7 +236,11 @@ export async function createGatewayRuntimeState(params: {
       releasePluginRouteRegistry: () => {
         // Releases both pinned HTTP-route and channel registries set at startup.
         releasePinnedPluginHttpRouteRegistry(params.pluginRegistry);
-        releasePinnedPluginChannelRegistry(params.pluginRegistry);
+        // Release unconditionally (no registry arg): the channel pin may have
+        // been re-pinned to a deferred-reload registry that differs from the
+        // original params.pluginRegistry, so an identity-guarded release would
+        // be a no-op and leak the pin across in-process restarts.
+        releasePinnedPluginChannelRegistry();
       },
       httpServer,
       httpServers,
@@ -258,7 +262,7 @@ export async function createGatewayRuntimeState(params: {
     };
   } catch (err) {
     releasePinnedPluginHttpRouteRegistry(params.pluginRegistry);
-    releasePinnedPluginChannelRegistry(params.pluginRegistry);
+    releasePinnedPluginChannelRegistry();
     throw err;
   }
 }

src/gateway/server.impl.ts

@@ -53,6 +53,7 @@ import { createSubsystemLogger, runtimeForLogger } from "../logging/subsystem.js
 import { resolveConfiguredDeferredChannelPluginIds } from "../plugins/channel-plugin-ids.js";
 import { getGlobalHookRunner, runGlobalGatewayStopSafely } from "../plugins/hook-runner-global.js";
 import { createEmptyPluginRegistry } from "../plugins/registry.js";
+import { pinActivePluginChannelRegistry } from "../plugins/runtime.js";
 import { createPluginRuntime } from "../plugins/runtime/index.js";
 import type { PluginServicesHandle } from "../plugins/services.js";
 import { getTotalQueueSize } from "../process/command-queue.js";
@@ -1195,6 +1196,10 @@ export async function startGatewayServer(
         baseMethods,
         logDiagnostics: false,
       }));
+      // Re-pin: the deferred reload replaces setup-entry channel objects with
+      // full runtime implementations. Update the pinned channel registry so
+      // getChannelPlugin() resolves against the complete set.
+      pinActivePluginChannelRegistry(pluginRegistry);
     }
     ({ browserControl, pluginServices } = await startGatewaySidecars({
       cfg: cfgAtStart,