feat(llm): report tool call errors

apps/client/src/services/llm_chat.ts

@@ -13,7 +13,7 @@ export interface StreamCallbacks {
     onChunk: (text: string) => void;
     onThinking?: (text: string) => void;
     onToolUse?: (toolName: string, input: Record<string, unknown>) => void;
-    onToolResult?: (toolName: string, result: string) => void;
+    onToolResult?: (toolName: string, result: string, isError?: boolean) => void;
     onCitation?: (citation: LlmCitation) => void;
     onUsage?: (usage: LlmUsage) => void;
     onError: (error: string) => void;
@@ -78,7 +78,7 @@ export async function streamChatCompletion(
                                 callbacks.onToolUse?.(data.toolName, data.toolInput);
                                 break;
                             case "tool_result":
-                                callbacks.onToolResult?.(data.toolName, data.result);
+                                callbacks.onToolResult?.(data.toolName, data.result, data.isError);
                                 break;
                             case "citation":
                                 if (data.citation) {

apps/client/src/translations/en/translation.json

@@ -1627,6 +1627,8 @@
     "tool_calls": "{{count}} tool call(s)",
     "input": "Input",
     "result": "Result",
+    "error": "Error",
+    "tool_error": "failed",
     "tokens_used": "{{prompt}} prompt + {{completion}} completion = {{total}} tokens",
     "tokens_used_with_cost": "{{prompt}} prompt + {{completion}} completion = {{total}} tokens (~${{cost}})",
     "tokens_used_with_model": "{{model}}: {{prompt}} prompt + {{completion}} completion = {{total}} tokens",

apps/client/src/widgets/type_widgets/llm_chat/ChatMessage.tsx

@@ -18,11 +18,17 @@ interface Props {
 }
 
 function ToolCallCard({ toolCall }: { toolCall: ToolCall }) {
+    const classes = [
+        "llm-chat-tool-call-inline",
+        toolCall.isError && "llm-chat-tool-call-error"
+    ].filter(Boolean).join(" ");
+
     return (
-        <details className="llm-chat-tool-call-inline">
+        <details className={classes}>
             <summary className="llm-chat-tool-call-inline-summary">
-                <span className="bx bx-wrench" />
+                <span className={toolCall.isError ? "bx bx-error-circle" : "bx bx-wrench"} />
                 {toolCall.toolName}
+                {toolCall.isError && <span className="llm-chat-tool-call-error-badge">{t("llm_chat.tool_error")}</span>}
             </summary>
             <div className="llm-chat-tool-call-inline-body">
                 <div className="llm-chat-tool-call-input">
@@ -30,8 +36,8 @@ function ToolCallCard({ toolCall }: { toolCall: ToolCall }) {
                     <pre>{JSON.stringify(toolCall.input, null, 2)}</pre>
                 </div>
                 {toolCall.result && (
-                    <div className="llm-chat-tool-call-result">
-                        <strong>{t("llm_chat.result")}:</strong>
+                    <div className={`llm-chat-tool-call-result ${toolCall.isError ? "llm-chat-tool-call-result-error" : ""}`}>
+                        <strong>{toolCall.isError ? t("llm_chat.error") : t("llm_chat.result")}:</strong>
                         <pre>{(() => {
                             if (typeof toolCall.result === "string" && (toolCall.result.startsWith("{") || toolCall.result.startsWith("["))) {
                                 try {

apps/client/src/widgets/type_widgets/llm_chat/LlmChat.css

@@ -588,6 +588,27 @@
     margin-top: 0.5rem;
 }
 
+/* Tool call error styling */
+.llm-chat-tool-call-error {
+    border-left-color: var(--danger-color, #dc3545);
+}
+
+.llm-chat-tool-call-error .llm-chat-tool-call-inline-summary {
+    color: var(--danger-color, #dc3545);
+}
+
+.llm-chat-tool-call-error-badge {
+    font-size: 0.75rem;
+    font-weight: 400;
+    font-family: var(--main-font-family);
+    color: var(--danger-color, #dc3545);
+    opacity: 0.8;
+}
+
+.llm-chat-tool-call-result-error pre {
+    color: var(--danger-color, #dc3545);
+}
+
 /* Token usage display */
 .llm-chat-usage {
     display: flex;

apps/client/src/widgets/type_widgets/llm_chat/llm_chat_types.ts

@@ -7,6 +7,7 @@ export interface ToolCall {
     toolName: string;
     input: Record<string, unknown>;
     result?: string;
+    isError?: boolean;
 }
 
 /** A block of text content (rendered as Markdown for assistant messages). */

apps/client/src/widgets/type_widgets/llm_chat/useLlmChat.ts

@@ -270,12 +270,13 @@ export function useLlmChat(
                         }
                     });
                 },
-                onToolResult: (toolName, result) => {
+                onToolResult: (toolName, result, isError) => {
                     // Find the most recent tool_call block for this tool without a result
                     for (let i = contentBlocks.length - 1; i >= 0; i--) {
                         const block = contentBlocks[i];
                         if (block.type === "tool_call" && block.toolCall.toolName === toolName && !block.toolCall.result) {
                             block.toolCall.result = result;
+                            block.toolCall.isError = isError;
                             break;
                         }
                     }

apps/server/src/services/llm/stream.ts

@@ -49,15 +49,19 @@ export async function* streamToChunks(result: StreamResult, options: StreamOptio
                     };
                     break;
 
-                case "tool-result":
+                case "tool-result": {
+                    const output = part.output;
+                    const isError = typeof output === "object" && output !== null && "error" in output;
                     yield {
                         type: "tool_result",
                         toolName: part.toolName,
-                        result: typeof part.output === "string"
-                            ? part.output
-                            : JSON.stringify(part.output)
+                        result: typeof output === "string"
+                            ? output
+                            : JSON.stringify(output),
+                        isError
                     };
                     break;
+                }
 
                 case "source":
                     // Citation from web search (only URL sources have url property)

packages/commons/src/lib/llm_api.ts

@@ -94,7 +94,7 @@ export type LlmStreamChunk =
     | { type: "text"; content: string }
     | { type: "thinking"; content: string }
     | { type: "tool_use"; toolName: string; toolInput: Record<string, unknown> }
-    | { type: "tool_result"; toolName: string; result: string }
+    | { type: "tool_result"; toolName: string; result: string; isError?: boolean }
     | { type: "citation"; citation: LlmCitation }
     | { type: "usage"; usage: LlmUsage }
     | { type: "error"; error: string }