feat: redesign agent harness with modular architecture + Responses API

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "uipath-dev"
-version = "0.0.63"
+version = "0.0.64"
 description = "UiPath Developer Console"
 readme = { file = "README.md", content-type = "text/markdown" }
 requires-python = ">=3.11"

src/uipath/dev/server/__init__.py

@@ -27,7 +27,7 @@
 from uipath.dev.models.eval_data import EvalItemResult, EvalRunState
 from uipath.dev.models.execution import ExecutionRun
 from uipath.dev.server.debug_bridge import WebDebugBridge
-from uipath.dev.services.agent_service import AgentService
+from uipath.dev.services.agent import AgentService
 from uipath.dev.services.eval_service import EvalService
 from uipath.dev.services.run_service import RunService
 from uipath.dev.services.skill_service import SkillService
@@ -102,13 +102,7 @@ def __init__(
 
         self.agent_service = AgentService(
             skill_service=self.skill_service,
-            on_status=self._on_agent_status,
-            on_text=self._on_agent_text,
-            on_plan=self._on_agent_plan,
-            on_tool_use=self._on_agent_tool_use,
-            on_tool_result=self._on_agent_tool_result,
-            on_tool_approval=self._on_agent_tool_approval,
-            on_error=self._on_agent_error,
+            on_event=self._on_agent_event,
         )
 
     def create_app(self) -> Any:
@@ -291,47 +285,52 @@ def _on_eval_run_completed(self, run: EvalRunState) -> None:
         """Broadcast eval run completed to all connected clients."""
         self.connection_manager.broadcast_eval_run_completed(run)
 
-    def _on_agent_status(self, session_id: str, status: str) -> None:
-        """Broadcast agent status to all connected clients."""
-        self.connection_manager.broadcast_agent_status(session_id, status)
-
-    def _on_agent_text(self, session_id: str, content: str, done: bool) -> None:
-        """Broadcast agent text to all connected clients."""
-        self.connection_manager.broadcast_agent_text(session_id, content, done)
-
-    def _on_agent_plan(self, session_id: str, items: list[dict[str, str]]) -> None:
-        """Broadcast agent plan to all connected clients."""
-        self.connection_manager.broadcast_agent_plan(session_id, items)
-
-    def _on_agent_tool_use(
-        self, session_id: str, tool: str, args: dict[str, Any]
-    ) -> None:
-        """Broadcast agent tool use to all connected clients."""
-        self.connection_manager.broadcast_agent_tool_use(session_id, tool, args)
-
-    def _on_agent_tool_result(
-        self, session_id: str, tool: str, result: str, is_error: bool
-    ) -> None:
-        """Broadcast agent tool result to all connected clients."""
-        self.connection_manager.broadcast_agent_tool_result(
-            session_id, tool, result, is_error
-        )
-
-    def _on_agent_tool_approval(
-        self,
-        session_id: str,
-        tool_call_id: str,
-        tool: str,
-        args: dict[str, Any],
-    ) -> None:
-        """Broadcast agent tool approval request to all connected clients."""
-        self.connection_manager.broadcast_agent_tool_approval(
-            session_id, tool_call_id, tool, args
+    def _on_agent_event(self, event: Any) -> None:
+        """Route agent events to the appropriate broadcast method."""
+        from uipath.dev.services.agent import (
+            ErrorOccurred,
+            PlanUpdated,
+            StatusChanged,
+            TextDelta,
+            TextGenerated,
+            ThinkingGenerated,
+            TokenUsageUpdated,
+            ToolApprovalRequired,
+            ToolCompleted,
+            ToolStarted,
         )
 
-    def _on_agent_error(self, session_id: str, message: str) -> None:
-        """Broadcast agent error to all connected clients."""
-        self.connection_manager.broadcast_agent_error(session_id, message)
+        cm = self.connection_manager
+        match event:
+            case StatusChanged(session_id=sid, status=status):
+                cm.broadcast_agent_status(sid, status)
+            case TextGenerated(session_id=sid, content=content, done=done):
+                cm.broadcast_agent_text(sid, content, done)
+            case TextDelta(session_id=sid, delta=delta):
+                cm.broadcast_agent_text_delta(sid, delta)
+            case ThinkingGenerated(session_id=sid, content=content):
+                cm.broadcast_agent_thinking(sid, content)
+            case PlanUpdated(session_id=sid, items=items):
+                cm.broadcast_agent_plan(sid, items)
+            case ToolStarted(session_id=sid, tool=tool, args=args):
+                cm.broadcast_agent_tool_use(sid, tool, args)
+            case ToolCompleted(
+                session_id=sid, tool=tool, result=result, is_error=is_error
+            ):
+                cm.broadcast_agent_tool_result(sid, tool, result, is_error)
+            case ToolApprovalRequired(
+                session_id=sid, tool_call_id=tcid, tool=tool, args=args
+            ):
+                cm.broadcast_agent_tool_approval(sid, tcid, tool, args)
+            case ErrorOccurred(session_id=sid, message=message):
+                cm.broadcast_agent_error(sid, message)
+            case TokenUsageUpdated(
+                session_id=sid,
+                prompt_tokens=pt,
+                completion_tokens=ct,
+                total_session_tokens=total,
+            ):
+                cm.broadcast_agent_token_usage(sid, pt, ct, total)
 
     @staticmethod
     def _find_free_port(host: str, start_port: int, max_attempts: int = 100) -> int:

src/uipath/dev/server/frontend/src/components/agent/AgentChatSidebar.tsx

@@ -85,6 +85,9 @@ export default function AgentChatSidebar() {
   });
 
   const isBusy = status === "thinking" || status === "executing" || status === "planning";
+  const lastMsg = messages[messages.length - 1];
+  const isStreaming = isBusy && lastMsg?.role === "assistant" && !lastMsg.done;
+  const showBusyIndicator = isBusy && !isStreaming;
 
   const textareaRef = useRef<HTMLTextAreaElement>(null);
 
@@ -191,7 +194,7 @@ export default function AgentChatSidebar() {
           {messages.map((msg) => (
             <AgentMessageComponent key={msg.id} message={msg} />
           ))}
-          {isBusy && (
+          {showBusyIndicator && (
             <div className="py-1.5">
               <div className="flex items-center gap-1.5">
                 <div className="w-2 h-2 rounded-full animate-pulse" style={{ background: "var(--success)" }} />

src/uipath/dev/server/frontend/src/components/agent/AgentMessage.tsx

@@ -15,8 +15,39 @@ const ROLE_CONFIG: Record<string, { label: string; color: string }> = {
   assistant: { label: "AI", color: "var(--success)" },
   tool: { label: "Tool", color: "var(--warning)" },
   plan: { label: "Plan", color: "var(--accent)" },
+  thinking: { label: "Reasoning", color: "var(--text-muted)" },
 };
 
+function ThinkingCard({ message }: Props) {
+  const [expanded, setExpanded] = useState(false);
+  return (
+    <div className="py-1.5">
+      <button
+        onClick={() => setExpanded(!expanded)}
+        className="flex items-center gap-1.5 mb-0.5 cursor-pointer"
+        style={{ background: "none", border: "none", padding: 0 }}
+      >
+        <div className="w-2 h-2 rounded-full" style={{ background: "var(--text-muted)", opacity: 0.5 }} />
+        <span className="text-[11px] font-semibold" style={{ color: "var(--text-muted)" }}>Reasoning</span>
+        <svg
+          width="10" height="10" viewBox="0 0 24 24" fill="none" stroke="var(--text-muted)" strokeWidth="2"
+          style={{ transform: expanded ? "rotate(180deg)" : "rotate(0deg)", transition: "transform 0.15s", marginLeft: 2 }}
+        >
+          <path d="M6 9l6 6 6-6" />
+        </svg>
+      </button>
+      {expanded && (
+        <div
+          className="text-[12px] leading-relaxed pl-2.5 max-w-prose whitespace-pre-wrap"
+          style={{ color: "var(--text-muted)", fontStyle: "italic" }}
+        >
+          {message.content}
+        </div>
+      )}
+    </div>
+  );
+}
+
 function PlanCard({ message }: Props) {
   const items = message.planItems ?? [];
   return (
@@ -234,6 +265,7 @@ function ToolCard({ message }: Props) {
 }
 
 export default function AgentMessageComponent({ message }: Props) {
+  if (message.role === "thinking") return <ThinkingCard message={message} />;
   if (message.role === "plan") return <PlanCard message={message} />;
   if (message.role === "tool") return <ToolCard message={message} />;
 

src/uipath/dev/server/frontend/src/store/useAgentStore.ts

@@ -26,6 +26,7 @@ interface AgentStore {
   addToolResult: (tool: string, result: string, isError: boolean) => void;
   addToolApprovalRequest: (toolCallId: string, tool: string, args: Record<string, unknown>) => void;
   resolveToolApproval: (toolCallId: string, approved: boolean) => void;
+  appendThinking: (content: string) => void;
   addError: (message: string) => void;
   setSessionId: (id: string) => void;
   setModels: (models: AgentModel[]) => void;
@@ -188,6 +189,24 @@ export const useAgentStore = create<AgentStore>((set) => ({
       return { messages: msgs };
     }),
 
+  appendThinking: (content) =>
+    set((state) => {
+      const msgs = [...state.messages];
+      const last = msgs[msgs.length - 1];
+      if (last && last.role === "thinking") {
+        // Append to existing thinking message
+        msgs[msgs.length - 1] = { ...last, content: last.content + content };
+      } else {
+        msgs.push({
+          id: nextId(),
+          role: "thinking",
+          content,
+          timestamp: Date.now(),
+        });
+      }
+      return { messages: msgs };
+    }),
+
   addError: (message) =>
     set((state) => ({
       status: "error" as AgentStatus,

src/uipath/dev/server/frontend/src/store/useWebSocket.ts

@@ -167,6 +167,22 @@ export function useWebSocket() {
           agent.addToolApprovalRequest(tool_call_id, tool, args);
           break;
         }
+        case "agent.thinking": {
+          const { content } = msg.payload as { session_id: string; content: string };
+          useAgentStore.getState().appendThinking(content);
+          break;
+        }
+        case "agent.text_delta": {
+          const { session_id: deltaSid, delta } = msg.payload as { session_id: string; delta: string };
+          const agentDelta = useAgentStore.getState();
+          if (!agentDelta.sessionId) agentDelta.setSessionId(deltaSid);
+          agentDelta.appendAssistantText(delta, false);
+          break;
+        }
+        case "agent.token_usage": {
+          // Token usage received — could store for display if needed
+          break;
+        }
         case "agent.error": {
           const { message: errMsg } = msg.payload as { session_id: string; message: string };
           useAgentStore.getState().addError(errMsg);

src/uipath/dev/server/frontend/src/types/agent.ts

@@ -14,7 +14,7 @@ export interface AgentToolCall {
 
 export interface AgentMessage {
   id: string;
-  role: "user" | "assistant" | "plan" | "tool";
+  role: "user" | "assistant" | "plan" | "tool" | "thinking";
   content: string;
   timestamp: number;
   toolCall?: AgentToolCall;

src/uipath/dev/server/frontend/src/types/ws.ts

@@ -16,7 +16,10 @@ export type ServerEventType =
   | "agent.tool_use"
   | "agent.tool_result"
   | "agent.tool_approval"
-  | "agent.error";
+  | "agent.error"
+  | "agent.thinking"
+  | "agent.text_delta"
+  | "agent.token_usage";
 
 export interface ServerMessage {
   type: ServerEventType;

src/uipath/dev/server/static/index.html

@@ -5,7 +5,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>UiPath Developer Console</title>
     <link rel="icon" type="image/x-icon" href="/favicon.ico" />
-    <script type="module" crossorigin src="/assets/index-B2xfJE6O.js"></script>
+    <script type="module" crossorigin src="/assets/index-DYl0Xnov.js"></script>
     <link rel="modulepreload" crossorigin href="/assets/vendor-react-BN_uQvcy.js">
     <link rel="modulepreload" crossorigin href="/assets/vendor-reactflow-BP_V7ttx.js">
     <link rel="stylesheet" crossorigin href="/assets/vendor-reactflow-B5DZHykP.css">

src/uipath/dev/server/ws/manager.py

@@ -301,6 +301,44 @@ def broadcast_agent_error(self, session_id: str, message: str) -> None:
         for ws in self._connections:
             self._enqueue(ws, msg)
 
+    def broadcast_agent_thinking(self, session_id: str, content: str) -> None:
+        """Broadcast agent thinking/reasoning to all connected clients."""
+        msg = server_message(
+            ServerEvent.AGENT_THINKING,
+            {"session_id": session_id, "content": content},
+        )
+        for ws in self._connections:
+            self._enqueue(ws, msg)
+
+    def broadcast_agent_text_delta(self, session_id: str, delta: str) -> None:
+        """Broadcast a streaming text token to all connected clients."""
+        msg = server_message(
+            ServerEvent.AGENT_TEXT_DELTA,
+            {"session_id": session_id, "delta": delta},
+        )
+        for ws in self._connections:
+            self._enqueue(ws, msg)
+
+    def broadcast_agent_token_usage(
+        self,
+        session_id: str,
+        prompt_tokens: int,
+        completion_tokens: int,
+        total_session_tokens: int,
+    ) -> None:
+        """Broadcast token usage stats to all connected clients."""
+        msg = server_message(
+            ServerEvent.AGENT_TOKEN_USAGE,
+            {
+                "session_id": session_id,
+                "prompt_tokens": prompt_tokens,
+                "completion_tokens": completion_tokens,
+                "total_session_tokens": total_session_tokens,
+            },
+        )
+        for ws in self._connections:
+            self._enqueue(ws, msg)
+
     def _schedule_broadcast(self, run_id: str, message: dict[str, Any]) -> None:
         """Enqueue a message for all subscribers of a run."""
         subscribers = self._subscriptions.get(run_id)

src/uipath/dev/server/ws/protocol.py

@@ -27,6 +27,9 @@ class ServerEvent(str, Enum):
     AGENT_TOOL_RESULT = "agent.tool_result"
     AGENT_TOOL_APPROVAL = "agent.tool_approval"
     AGENT_ERROR = "agent.error"
+    AGENT_THINKING = "agent.thinking"
+    AGENT_TEXT_DELTA = "agent.text_delta"
+    AGENT_TOKEN_USAGE = "agent.token_usage"
 
 
 class ClientCommand(str, Enum):

src/uipath/dev/services/agent/__init__.py

@@ -0,0 +1,33 @@
+"""Agent harness — deep agent architecture with loop innovations."""
+
+from uipath.dev.services.agent.events import (
+    AgentEvent,
+    ErrorOccurred,
+    PlanUpdated,
+    StatusChanged,
+    TextDelta,
+    TextGenerated,
+    ThinkingGenerated,
+    TokenUsageUpdated,
+    ToolApprovalRequired,
+    ToolCompleted,
+    ToolStarted,
+)
+from uipath.dev.services.agent.service import AgentService
+from uipath.dev.services.agent.session import AgentSession
+
+__all__ = [
+    "AgentEvent",
+    "AgentService",
+    "AgentSession",
+    "ErrorOccurred",
+    "PlanUpdated",
+    "StatusChanged",
+    "TextDelta",
+    "TextGenerated",
+    "ThinkingGenerated",
+    "TokenUsageUpdated",
+    "ToolApprovalRequired",
+    "ToolCompleted",
+    "ToolStarted",
+]