fix(vscode): address CodeRabbit findings on workflow lanes

Pluralize the lane step count, add aria-expanded to the lane toggle,
guard parseArgs against non-object JSON.parse results, merge duplicate
tool-label cases, and gate the lane-failure sweep on the parent
ToolResult's is_error flag so a successful batch result no longer
marks still-running lanes as failed.

Author: elkaix

apps/vscode/test/event-handlers.test.ts

@@ -6,6 +6,9 @@
  * Run: pnpm exec vitest run --config apps/vscode/vitest.config.ts test/event-handlers.test.ts
  */
 import { beforeEach, describe, expect, it, vi } from "vitest";
+import { useChatStore } from "../webview-ui/src/stores/chat.store";
+import { deriveWorkflowLanes, maxLaneStepCount } from "../webview-ui/src/lib/workflow-lanes";
+import type { UIStepItem } from "../webview-ui/src/stores/chat.store";
 
 const boundary = vi.hoisted(() => ({
   saveConfig: vi.fn(),
@@ -28,10 +31,6 @@ vi.mock("@/components/ui/sonner", () => ({
   toast: { error: boundary.toastError, warning: boundary.toastWarning },
 }));
 
-import { useChatStore } from "../webview-ui/src/stores/chat.store";
-import { deriveWorkflowLanes, maxLaneStepCount } from "../webview-ui/src/lib/workflow-lanes";
-import type { UIStepItem } from "../webview-ui/src/stores/chat.store";
-
 beforeEach(() => {
   boundary.streamChat.mockReset();
   boundary.abortChat.mockReset();
@@ -220,6 +219,28 @@ describe("Webview DynamicWorkflow per-agent lanes", () => {
     // Already-terminal lanes are left alone.
     expect(status["agentC"]!.status).toBe("done");
   });
+
+  it("leaves spawned/running lanes alone when the parent ToolResult succeeds", () => {
+    startWorkflowTurn();
+
+    useChatStore.getState().processEvent({
+      type: "SubagentStatus",
+      payload: { parent_tool_call_id: "wf-1", agent_id: "agentA", agent_label: "explore", agent_index: 1, status: "spawned" },
+    });
+    useChatStore.getState().processEvent({
+      type: "SubagentStatus",
+      payload: { parent_tool_call_id: "wf-1", agent_id: "agentA", status: "running" },
+    });
+
+    useChatStore.getState().processEvent({
+      type: "ToolResult",
+      payload: { tool_call_id: "wf-1", return_value: { is_error: false, output: "ok", message: "", display: [] } },
+    });
+
+    const status = workflowToolItem().subagent_status!;
+    expect(status["agentA"]!.status).toBe("running");
+    expect(status["agentA"]!.endedAt).toBeUndefined();
+  });
 });
 
 describe("workflow lane derivation", () => {

apps/vscode/webview-ui/src/components/WorkflowCard.tsx

@@ -63,12 +63,12 @@ function LaneRow({ lane, maxSteps, renderStepItem }: { lane: WorkflowLane; maxSt
 
   return (
     <div className="text-xs">
-      <button onClick={() => setExpanded(!expanded)} className="w-full flex items-center gap-2 py-1 hover:bg-muted/50 transition-colors text-left" disabled={lane.stepCount === 0}>
+      <button onClick={() => setExpanded(!expanded)} aria-expanded={expanded} className="w-full flex items-center gap-2 py-1 hover:bg-muted/50 transition-colors text-left" disabled={lane.stepCount === 0}>
         <StatusDot status={lane.status} />
         <span className="font-mono text-[11px] shrink-0">{laneLabel(lane)}</span>
         <LaneBar fraction={fraction} done={done} />
         <span className="text-muted-foreground tabular-nums shrink-0">
-          {queued ? "queued" : `${lane.status === "done" ? "done · " : ""}${lane.stepCount} steps`}
+          {queued ? "queued" : `${lane.status === "done" ? "done · " : ""}${lane.stepCount} step${lane.stepCount === 1 ? "" : "s"}`}
           {duration && ` · ${duration}`}
         </span>
         {lane.stepCount > 0 && (expanded ? <IconChevronDown className="size-3 text-muted-foreground" /> : <IconChevronRight className="size-3 text-muted-foreground" />)}

apps/vscode/webview-ui/src/lib/tool-args.ts

@@ -5,7 +5,11 @@ export function parseArgs(args: string | null): Record<string, unknown> {
     return {};
   }
   try {
-    return JSON.parse(args);
+    const parsed: unknown = JSON.parse(args);
+    if (typeof parsed !== "object" || parsed === null || Array.isArray(parsed)) {
+      return { raw: args };
+    }
+    return parsed as Record<string, unknown>;
   } catch {
     return { raw: args };
   }
@@ -17,9 +21,7 @@ export function getToolLabel(call: UIToolCall): string {
     case "Shell":
       return (args.command as string) || "command";
     case "ReadFile":
-      return (args.path as string)?.split("/").pop() || "file";
     case "WriteFile":
-      return (args.path as string)?.split("/").pop() || "file";
     case "StrReplaceFile":
       return (args.path as string)?.split("/").pop() || "file";
     case "Glob":

apps/vscode/webview-ui/src/stores/event-handlers.ts

@@ -285,7 +285,7 @@ function applyEventToSteps(
 
       // Batch aborted: lanes still spawned/running when the parent result lands
       // have no further lifecycle events coming, so freeze them as failed.
-      if (toolItem?.subagent_status) {
+      if (result.return_value.is_error && toolItem?.subagent_status) {
         for (const status of Object.values(toolItem.subagent_status)) {
           if (status.status === "spawned" || status.status === "running") {
             status.status = "failed";