fix(web,gateway): close P3 re-review#3 findings — sanitize command errors, harden turn-lock & caps

apps/web/src/spa/chat/commands-panel.tsx

@@ -1,5 +1,6 @@
 import { useState, type ReactElement } from 'react';
 import type { PendingApproval } from './use-chat-connection';
+import { MAX_COMMAND_MESSAGE_CHARS } from './limits';
 import { asNonEmptyString, asString } from './runtime-guards';
 import type {
   CommandManifest,
@@ -13,6 +14,16 @@ import type {
  * directly, never a raw thrown exception, stack trace, or object value. */
 const COMMAND_FAILURE_COPY = 'Command failed.';
 
+/** Render-site defense-in-depth: `use-chat-connection.ts` already bounds a
+ * stored command:result message at ingestion, but this component must never
+ * assume every caller went through that path — bounding again here means a
+ * hostile/oversized message can never force an unbounded render. */
+function boundMessage(value: string): string {
+  return value.length > MAX_COMMAND_MESSAGE_CHARS
+    ? value.slice(0, MAX_COMMAND_MESSAGE_CHARS)
+    : value;
+}
+
 interface CommandsPanelProps {
   manifest: CommandManifest | null;
   results: SlashCommandResultPayload[];
@@ -141,9 +152,9 @@ export function CommandsPanel({
               /{asString(result.command)}: {result.success ? 'success' : 'failed'}
               {result.success
                 ? typeof result.message === 'string' && result.message
-                  ? ` — ${result.message}`
+                  ? ` — ${boundMessage(result.message)}`
                   : ''
-                : ` — ${asNonEmptyString(result.message, COMMAND_FAILURE_COPY)}`}
+                : ` — ${boundMessage(asNonEmptyString(result.message, COMMAND_FAILURE_COPY))}`}
             </li>
           ))}
         </ul>