feat(hooks): emit gateway shutdown lifecycle events

src/gateway/server-close.ts

@@ -5,6 +5,7 @@ import { disposeAllSessionMcpRuntimes } from "../agents/pi-bundle-mcp-tools.js";
 import type { CanvasHostHandler, CanvasHostServer } from "../canvas-host/server.js";
 import { type ChannelId, listChannelPlugins } from "../channels/plugins/index.js";
 import { stopGmailWatcher } from "../hooks/gmail-watcher.js";
+import { createInternalHookEvent, triggerInternalHook } from "../hooks/internal-hooks.js";
 import type { HeartbeatRunner } from "../infra/heartbeat-runner.js";
 import { createSubsystemLogger } from "../logging/subsystem.js";
 import type { PluginServicesHandle } from "../plugins/services.js";
@@ -113,6 +114,27 @@ export function createGatewayCloseHandler(params: {
         typeof opts?.restartExpectedMs === "number" && Number.isFinite(opts.restartExpectedMs)
           ? Math.max(0, Math.floor(opts.restartExpectedMs))
           : null;
+      try {
+        const shutdownEvent = createInternalHookEvent("gateway", "shutdown", "gateway:shutdown", {
+          reason,
+          restartExpectedMs,
+        });
+        await triggerInternalHook(shutdownEvent);
+        if (restartExpectedMs !== null) {
+          const preRestartEvent = createInternalHookEvent(
+            "gateway",
+            "pre-restart",
+            "gateway:pre-restart",
+            {
+              reason,
+              restartExpectedMs,
+            },
+          );
+          await triggerInternalHook(preRestartEvent);
+        }
+      } catch {
+        // Best-effort only; shutdown should proceed even if hooks fail.
+      }
       if (params.bonjourStop) {
         try {
           await params.bonjourStop();