feat: resolve sandbox file paths and show tool description in status

- Extract resolve_sandbox_script utility in sandbox_tool.py to detect
file paths and read content from sandbox via cat
- Resolve script paths before sending approval_required event so the
frontend receives actual file content for display and editing
- Show tool description arg in status chip and activity bar instead of
generic "running" / "Running bash" text

frontend/src/components/Chat/ActivityStatusBar.tsx

@@ -21,7 +21,7 @@ function statusLabel(status: ActivityStatus): string {
   switch (status.type) {
     case 'thinking': return 'Thinking';
     case 'streaming': return 'Writing';
-    case 'tool': return TOOL_LABELS[status.toolName] || `Running ${status.toolName}`;
+    case 'tool': return status.description || TOOL_LABELS[status.toolName] || `Running ${status.toolName}`;
     case 'waiting-approval': return 'Waiting for approval';
     default: return '';
   }

frontend/src/components/Chat/ToolCallGroup.tsx

@@ -496,7 +496,9 @@ export default function ToolCallGroup({ tools, approveTools }: ToolCallGroupProp
           const displayState = isPending && localDecision
             ? (localDecision.approved ? 'input-available' : 'output-denied')
             : state;
-          const label = statusLabel(displayState as ToolPartState);
+          const baseLabel = statusLabel(displayState as ToolPartState);
+          const toolDescription = (tool.input as Record<string, unknown>)?.description as string | undefined;
+          const label = baseLabel ? (toolDescription || baseLabel) : null;
 
           // Parse job metadata from hf_jobs output and store
           const jobUrlFromStore = tool.toolName === 'hf_jobs' ? getJobUrl(tool.toolCallId) : undefined;
@@ -546,7 +548,7 @@ export default function ToolCallGroup({ tools, approveTools }: ToolCallGroupProp
                     whiteSpace: 'nowrap',
                   }}
                 >
-                  {toolDisplayMap[tool.toolCallId] || String((tool.input as Record<string, unknown>)?.description || '') || tool.toolName}
+                  {toolDisplayMap[tool.toolCallId] || tool.toolName}
                 </Typography>
 
                 {/* Status chip (non hf_jobs, or hf_jobs without final status) */}

frontend/src/hooks/useAgentChat.ts

@@ -195,8 +195,8 @@ export function useAgentChat({ sessionId, isActive, onReady, onError, onSessionD
       onStreaming: () => {
         if (isActiveRef.current) setActivityStatus({ type: 'streaming' });
       },
-      onToolRunning: (toolName: string) => {
-        if (isActiveRef.current) setActivityStatus({ type: 'tool', toolName });
+      onToolRunning: (toolName: string, description?: string) => {
+        if (isActiveRef.current) setActivityStatus({ type: 'tool', toolName, description });
       },
     }),
     // sessionId is the only real dependency — Zustand setters are stable

frontend/src/lib/ws-chat-transport.ts

@@ -35,7 +35,7 @@ export interface SideChannelCallbacks {
   /** Called when assistant text starts streaming */
   onStreaming: () => void;
   /** Called when a tool starts running (non-plan) */
-  onToolRunning: (toolName: string) => void;
+  onToolRunning: (toolName: string, description?: string) => void;
 }
 
 // ---------------------------------------------------------------------------
@@ -499,7 +499,7 @@ export class WebSocketChatTransport implements ChatTransport<UIMessage> {
         this.enqueue({ type: 'tool-input-start', toolCallId, toolName, dynamic: true });
         this.enqueue({ type: 'tool-input-available', toolCallId, toolName, input: args, dynamic: true });
 
-        this.sideChannel.onToolRunning(toolName);
+        this.sideChannel.onToolRunning(toolName, (args as Record<string, unknown>)?.description as string | undefined);
         this.sideChannel.onToolCallPanel(toolName, args as Record<string, unknown>);
         break;
       }

frontend/src/store/agentStore.ts

@@ -41,7 +41,7 @@ export interface LLMHealthError {
 export type ActivityStatus =
   | { type: 'idle' }
   | { type: 'thinking' }
-  | { type: 'tool'; toolName: string }
+  | { type: 'tool'; toolName: string; description?: string }
   | { type: 'waiting-approval' }
   | { type: 'streaming' };