v1.11.6: doom-loop guard (3 identical tool calls aborts recursion)

apps/web/src/api/types.ts

@@ -112,11 +112,13 @@ export type ErrorReason =
   | 'tool_execution_failed'
   | 'summary_after_cap_failed';
 
-// v1.8.2: shapes stored in Message.metadata. Discriminated on `kind`.
-//   cap_hit — sentinel emitted when the tool budget is hit; carries the
-//             budget + agent name + whether Continue is still allowed.
-//   error   — attached to a failed assistant message so the bubble can show
-//             a specific reason on reload (WS error frame is one-shot).
+// v1.8.2 / v1.11.6: shapes stored in Message.metadata. Discriminated on `kind`.
+//   cap_hit    — sentinel emitted when the tool budget is hit; carries the
+//                budget + agent name + whether Continue is still allowed.
+//   doom_loop  — sentinel emitted when the model called the same tool with
+//                the same arguments threshold times in a row.
+//   error      — attached to a failed assistant message so the bubble can show
+//                a specific reason on reload (WS error frame is one-shot).
 export type MessageMetadata =
   | {
       kind: 'cap_hit';
@@ -125,6 +127,12 @@ export type MessageMetadata =
       agent_name: string | null;
       can_continue: boolean;
     }
+  | {
+      kind: 'doom_loop';
+      tool_name: string;
+      args: Record<string, unknown>;
+      threshold: number;
+    }
   | {
       kind: 'error';
       error_reason: ErrorReason;

apps/web/src/components/DoomLoopSentinel.tsx

@@ -0,0 +1,43 @@
+import { AlertCircle } from 'lucide-react';
+import type { Message } from '@/api/types';
+
+interface Props {
+  message: Message;
+}
+
+// v1.11.6: doom-loop sentinel. Renders the system row inserted by
+// services/inference.ts insertDoomLoopSentinel when the model called the
+// same tool with the same arguments threshold times in a row. Visual
+// treatment mirrors CapHitSentinel (amber card + alert icon) so users learn
+// "amber alert = the loop hit a guard rail and stopped" regardless of
+// which guard fired. Intentionally NO Continue button — retrying with the
+// same tools would just re-loop; the user needs to restate the prompt or
+// switch agents instead.
+export function DoomLoopSentinel({ message }: Props) {
+  const meta = message.metadata;
+  const isDoomLoop =
+    meta !== null && typeof meta === 'object' && meta.kind === 'doom_loop';
+  const toolName = isDoomLoop ? meta.tool_name : null;
+  const threshold = isDoomLoop ? meta.threshold : null;
+
+  return (
+    <div className="rounded-md border border-amber-500/40 bg-amber-500/10 text-sm">
+      <div className="px-3 py-2 flex items-start gap-2">
+        <AlertCircle className="size-4 text-amber-500 shrink-0 mt-0.5" />
+        <div className="flex-1 min-w-0 space-y-1">
+          <div className="text-xs font-medium text-amber-700 dark:text-amber-300">
+            Doom loop detected
+          </div>
+          <div className="text-xs text-muted-foreground">
+            {toolName !== null && threshold !== null
+              ? `Stopped after ${threshold} identical calls to ${toolName}. The model was looping.`
+              : message.content}
+          </div>
+          <div className="text-[11px] text-muted-foreground/80">
+            Send a new message with a different angle, or switch agents.
+          </div>
+        </div>
+      </div>
+    </div>
+  );
+}

apps/web/src/components/MessageBubble.tsx

@@ -9,6 +9,7 @@ import { api } from '@/api/client';
 import { sessionEvents } from '@/hooks/sessionEvents';
 import { sendToTerminal, terminalsRegistry, type TerminalRegistration } from '@/lib/events';
 import { CapHitSentinel } from './CapHitSentinel';
+import { DoomLoopSentinel } from './DoomLoopSentinel';
 import { CodeBlock } from './CodeBlock';
 import { Button } from '@/components/ui/button';
 import {
@@ -622,6 +623,13 @@ export function MessageBubble({ message, sessionChats, capHitInfo }: Props) {
     );
   }
 
+  // v1.11.6: doom-loop sentinel. No Continue affordance — retrying with the
+  // same tools would just re-loop. The card explains what tripped and
+  // suggests next steps (new message angle / switch agents).
+  if (message.role === 'system' && message.metadata?.kind === 'doom_loop') {
+    return <DoomLoopSentinel message={message} />;
+  }
+
   // v1.8.2: tool messages and assistant tool_calls are now rendered by
   // MessageList via ToolCallLine / ToolCallGroup. Tool-role messages reach
   // this point only if MessageList didn't consume them (shouldn't happen,