refactor(agent-service): remove dead checkout/headChange path

agent-service/src/agent/texera-agent.ts

@@ -75,7 +75,7 @@ type ReActStepCallback = (step: ReActStep) => void;
 /**
  * A single Texera agent instance.
  *
- * Owns the conversation (ReAct step tree with HEAD/checkout semantics), the
+ * Owns the conversation (ReAct step tree with HEAD tracking), the
  * workflow being edited (`WorkflowState`), cached operator execution results
  * (`WorkflowResultState`), and the tool surface exposed to the LLM. Each call
  * to `sendMessage` drives one multi-step generation via the Vercel AI SDK,
@@ -298,16 +298,6 @@ export class TexeraAgent {
     return Array.from(this.stepsById.values()).filter(s => s.id !== INITIAL_STEP_ID);
   }
 
-  checkout(stepId: string): boolean {
-    const step = this.stepsById.get(stepId);
-    if (!step && stepId !== INITIAL_STEP_ID) return false;
-    this.head = stepId;
-    if (step?.afterWorkflowContent) {
-      this.workflowState.setWorkflowContent(step.afterWorkflowContent);
-    }
-    return true;
-  }
-
   setStepCallback(callback: ReActStepCallback | null): void {
     this.stepCallback = callback;
   }

agent-service/src/server.ts

@@ -308,31 +308,6 @@ const agentsRouter = new Elysia({ prefix: "/agents" })
     return { status: "cleared" };
   })
 
-  .post("/:id/checkout", ({ params: { id }, body }) => {
-    const agent = getAgent(id);
-    const { stepId } = body as { stepId: string };
-    if (!stepId) throw new Error("stepId is required");
-
-    const success = agent.checkout(stepId);
-    if (!success) throw new Error(`Step ${stepId} not found or checkout failed`);
-
-    const allSteps = agent.getAllSteps();
-    const workflowContent = agent.getWorkflowState().getWorkflowContent();
-
-    broadcastToAgent(id, {
-      type: "headChange",
-      headId: stepId,
-      steps: allSteps,
-      workflowContent,
-      operatorResults: getOperatorResultSummaries(agent),
-    });
-
-    return {
-      status: "checked out",
-      headId: stepId,
-    };
-  })
-
   .get("/:id/operator-types", ({ params: { id } }) => {
     const agent = getAgent(id);
     const metadataStore = agent.getMetadataStore();
@@ -431,14 +406,13 @@ interface OperatorResultSummaryWs {
 }
 
 interface WsOutgoingMessage {
-  type: "step" | "state" | "error" | "complete" | "init" | "headChange";
+  type: "step" | "state" | "error" | "complete" | "init";
   step?: ReActStep;
   state?: string;
   error?: string;
   steps?: ReActStep[];
   headId?: string;
   operatorResults?: Record<string, OperatorResultSummaryWs>;
-  workflowContent?: any;
 }
 
 function getOperatorResultSummaries(agent: TexeraAgent): Record<string, OperatorResultSummaryWs> {

frontend/src/app/workspace/service/agent/agent.service.ts

@@ -534,30 +534,6 @@ export class AgentService {
         }
         break;
 
-      case "headChange":
-        // HEAD moved (checkout) — update HEAD, visible steps, and workflow
-        if (message.headId !== undefined) {
-          tracking.headIdSubject.next(message.headId);
-        }
-        if (message.steps && Array.isArray(message.steps)) {
-          const steps = message.steps.map((s: any) => this.convertApiReActStep(s));
-          tracking.reActStepsSubject.next(steps);
-        }
-        // Update workflow content from agent service (ground truth)
-        if (message.workflowContent) {
-          tracking.wsWorkflowActive = true;
-          const workflow: Workflow = {
-            ...(message.workflowMetadata || tracking.workflowSubject.getValue() || {}),
-            content: message.workflowContent,
-          };
-          tracking.workflowSubject.next(workflow as Workflow);
-        }
-        // Update operator results on HEAD change
-        if (message.operatorResults) {
-          this.updateOperatorResultSummaries(message.operatorResults);
-        }
-        break;
-
       case "error":
         // Error occurred
         console.error(`Agent ${agentId} error:`, message.error);
@@ -1025,14 +1001,6 @@ export class AgentService {
     return tracking ? tracking.headIdSubject.getValue() : null;
   }
 
-  /**
-   * Checkout to a specific step (move HEAD, restore workflow).
-   * The backend broadcasts headChange + visible steps via WebSocket to all clients.
-   */
-  public checkoutStep(agentId: string, stepId: string): Observable<any> {
-    return this.http.post(`${this.AGENT_API_BASE}/agents/${agentId}/checkout`, { stepId });
-  }
-
   /**
    * Get visible steps for an agent (current snapshot).
    */