fix(mattermost): harden slash abort/lookup error paths

extensions/mattermost/src/mattermost/monitor.ts

@@ -1163,7 +1163,10 @@ export async function monitorMattermostProvider(opts: MonitorMattermostOpts = {}
 
   // Clean up slash commands on shutdown
   if (slashEnabled) {
-    const onAbortCleanup = () => {
+    const runAbortCleanup = () => {
+      if (slashShutdownCleanup) {
+        return;
+      }
       // Snapshot registered commands before deactivating state.
       // This listener may run concurrently with startup in a new process, so we keep
       // monitor shutdown alive until the remote cleanup completes.
@@ -1179,7 +1182,12 @@ export async function monitorMattermostProvider(opts: MonitorMattermostOpts = {}
         runtime.error?.(`mattermost: slash cleanup failed: ${String(err)}`);
       });
     };
-    opts.abortSignal?.addEventListener("abort", onAbortCleanup, { once: true });
+
+    if (opts.abortSignal?.aborted) {
+      runAbortCleanup();
+    } else {
+      opts.abortSignal?.addEventListener("abort", runAbortCleanup, { once: true });
+    }
   }
 
   await runWithReconnect(connectOnce, {

extensions/mattermost/src/mattermost/slash-http.ts

@@ -132,8 +132,9 @@ async function authorizeSlashInvocation(params: {
   channelId: string;
   senderId: string;
   senderName: string;
+  log?: (msg: string) => void;
 }): Promise<SlashInvocationAuth> {
-  const { account, cfg, client, commandText, channelId, senderId, senderName } = params;
+  const { account, cfg, client, commandText, channelId, senderId, senderName, log } = params;
   const core = getMattermostRuntime();
 
   // Resolve channel info so we can enforce DM vs group/channel policies.
@@ -443,6 +444,7 @@ export function createSlashCommandHttpHandler(params: SlashHttpHandlerParams) {
       channelId,
       senderId,
       senderName,
+      log,
     });
 
     if (!auth.ok) {