From 3deb3ef4e0336ec0ec41e6abfc0bfc22e128743b Mon Sep 17 00:00:00 2001
From: Johannes du Plessis <johannes@langchain.dev>
Date: Mon, 15 Jun 2026 10:53:28 -0700
Subject: [PATCH] fix: show subagent current status instead of full tool-call
 list (#1528)

The subagent card listed every nested tool call, ballooning the card as
the subagent ran. Show a single status line (current activity + step
count) until a richer activity UI lands.

Co-authored-by: open-swe[bot] <open-swe@users.noreply.github.com>
---
 .../agents/subagents/SubagentActivity.tsx     | 53 ++++++++++---------
 1 file changed, 28 insertions(+), 25 deletions(-)

diff --git a/ui/src/components/agents/subagents/SubagentActivity.tsx b/ui/src/components/agents/subagents/SubagentActivity.tsx
index 286dcd9c..88e22e54 100644
--- a/ui/src/components/agents/subagents/SubagentActivity.tsx
+++ b/ui/src/components/agents/subagents/SubagentActivity.tsx
@@ -6,12 +6,16 @@ function humanizeToolName(name: string): string {
 }
 
 /**
- * Live nested activity for a single subagent, read straight from the SDK's
- * scoped `tools` projection (`useToolCalls(stream, { namespace })`). The
- * namespace comes from `stream.subagents` (attached to the `task` chunk by
+ * Live status for a single subagent, read straight from the SDK's scoped
+ * `tools` projection (`useToolCalls(stream, { namespace })`). The namespace
+ * comes from `stream.subagents` (attached to the `task` chunk by
  * `streamMessagesToUi`), so this subscribes to exactly the subagent that the
  * parent card represents.
  *
+ * Hotfix: rather than listing every nested tool call (which balloons the card),
+ * this shows a single line with the subagent's current activity plus a running
+ * step count. A richer activity UI will replace this later.
+ *
  * Mounting opens a ref-counted subscription scoped to `namespace`; unmounting
  * closes it. Only mounted from {@link SubagentCard} when
  * `useIsInAgentThreadStream()` is true, so the `useStreamContext` read is
@@ -21,30 +25,29 @@ export function SubagentActivity({ namespace }: { namespace: Array<string> }) {
   const stream = useAgentThreadStream()
   const toolCalls = useToolCalls(stream, { namespace })
 
-  if (toolCalls.length === 0) return null
+  const current = toolCalls[toolCalls.length - 1]
+  if (!current) return null
+
+  const stepCount = toolCalls.length
 
   return (
-    <div className="mt-1 flex flex-col gap-1 border-t border-[var(--ui-border)] pt-1.5">
-      {toolCalls.map((toolCall, index) => {
-        const id = toolCall.id || toolCall.callId || `sub-tool-${index}`
-        return (
-          <div key={id} className="flex min-w-0 items-center gap-1.5">
-            {toolCall.status === "finished" ? (
-              <Check className="h-3 w-3 shrink-0 text-[color:var(--ui-accent)]" aria-hidden />
-            ) : toolCall.status === "error" ? (
-              <X className="h-3 w-3 shrink-0 text-red-400" aria-hidden />
-            ) : (
-              <Loader2
-                className="h-3 w-3 shrink-0 animate-spin text-[color:var(--ui-text-dim)]"
-                aria-hidden
-              />
-            )}
-            <span className="truncate text-[10px] text-[color:var(--ui-text-dim)]">
-              {humanizeToolName(toolCall.name)}
-            </span>
-          </div>
-        )
-      })}
+    <div className="mt-1 flex min-w-0 items-center gap-1.5 border-t border-[var(--ui-border)] pt-1.5">
+      {current.status === "finished" ? (
+        <Check className="h-3 w-3 shrink-0 text-[color:var(--ui-accent)]" aria-hidden />
+      ) : current.status === "error" ? (
+        <X className="h-3 w-3 shrink-0 text-red-400" aria-hidden />
+      ) : (
+        <Loader2
+          className="h-3 w-3 shrink-0 animate-spin text-[color:var(--ui-text-dim)]"
+          aria-hidden
+        />
+      )}
+      <span className="truncate text-[10px] text-[color:var(--ui-text-dim)]">
+        {humanizeToolName(current.name)}
+      </span>
+      <span className="ml-auto shrink-0 text-[10px] tabular-nums text-[color:var(--ui-text-dim)]">
+        {stepCount} {stepCount === 1 ? "step" : "steps"}
+      </span>
     </div>
   )
 }