Sub-agents not visible: Claude Code 2.1.71 no longer emits agent_progress records for Agent tool

[Revdep]

Description

Sub-agent characters are not spawned on the Pixel Agents map when Claude Code uses the Agent tool to launch sub-agents. Only the parent agent character is visible.

Root Cause Analysis

After investigating the JSONL transcript files, I found two issues:

Issue 1: Tool name mismatch (Agent vs Task)

Pixel Agents expects the tool to be named "Task", but Claude Code (at least in VSCode extension / Claude Agent SDK context) uses "Agent" as the tool name.

In extension.js, the progress handler Pr() filters with:

if(o.activeToolNames.get(l)!=="Task") return;

And the status generator it() only has:

case "Task": { ... return `Subtask: ${...}` }

The Agent tool is not recognized, so:

• No "Subtask: ..." status is generated for it
• Progress records from Agent sub-agents are silently dropped

Suggested fix: Add "Agent" as an alias for "Task" in both places:

// Status generator
case "Agent":
case "Task": { ... }

// Progress handler
if(o.activeToolNames.get(l)!=="Task" && o.activeToolNames.get(l)!=="Agent") return;

Issue 2: agent_progress records missing in Claude Code 2.1.71+

Even with the above patch applied locally, sub-agents still don't appear. Comparing JSONL transcripts:

• Claude Code 2.1.69: Emits agent_progress records in the parent session JSONL with data.type: "agent_progress" and parentToolUseID — Pixel Agents can detect sub-agent activity.
• Claude Code 2.1.71: No agent_progress records are emitted. Only hook_progress records appear. The sub-agent tool calls (Agent) are recorded as tool_use/tool_result blocks, but without the streaming progress records that Pixel Agents relies on to spawn and animate sub-agent characters.

This means that even with Issue 1 fixed, Pixel Agents cannot detect sub-agents in Claude Code 2.1.71+ because the data it needs is simply not written to the JSONL file.

Environment

• Pixel Agents: v1.0.2
• Claude Code: v2.1.69 (agent_progress works) and v2.1.71 (agent_progress missing)
• Platform: Linux (VSCode Remote SSH / vscode-server)
• Extension path: ~/.vscode-server/extensions/pablodelucca.pixel-agents-1.0.2/

Steps to Reproduce

1. Open a Pixel Agents terminal with "+ Agent"
2. Run a command that launches sub-agents (e.g., a PR review skill that spawns multiple specialized agents via the Agent tool)
3. Only the parent agent appears on the map; sub-agents are never spawned

Evidence

JSONL from Claude Code 2.1.69 (sub-agents detected):

{
  "type": "progress",
  "parentToolUseID": "toolu_01G1pN...",
  "data": {
    "type": "agent_progress",
    "agentId": "aef9bb38...",
    "message": { "type": "assistant", ... }
  }
}

JSONL from Claude Code 2.1.71 (no agent_progress at all):

$ grep "agent_progress" session-2.1.71.jsonl | wc -l
0

Suggested Next Steps

1. Fix Issue 1 (tool name Agent vs Task) in Pixel Agents
2. Open a companion issue on Claude Code asking about the removal of agent_progress records in 2.1.71+, or adapt Pixel Agents to detect sub-agents from the tool_use/tool_result blocks directly

[gaby]

@Revdep Issue 2 was documented here #7

I really doubt that claude-code is going to add those events back into the JSONL. They got rid of them because the file was getting bloated.

Ping @pablodelucca

[pablodelucca]

Thanks for reporting this @Revdep! I'm working on a fix for issue 1 that should be up by the next release, but I'm not getting issue 2 myself. What OS are you on? I'm in Claude Code v2.1.71 in Windows 11 and I do get agent_progress updates:

{
  ...
  "type": "progress",
  "data": {
    "type": "agent_progress",
    "prompt": "",
    "agentId": "a8de2f7044fa36496",
    "message": {
      "type": "assistant",
      "message": {
        "role": "assistant",
        "content": [
          {
            "type": "tool_use",
            "id": "toolu_01Fs6...",
            "name": "WebSearch",
            "input": {
              "query": "..."
            }
          }
        ]
      }
    }
  },
  "toolUseID": "agent_msg_01N3j...",
  "parentToolUseID": "toolu_015ez..."
}

@gaby are you also not seeing agent_progress in the JSONLs?

[gaby]

@pablodelucca I'm using v2.1.71 with Ubuntu 24.04 installed claude using the binary running out of /home/<username>/.local/bin/claude

[Revdep]

Thanks @pablodelucca!

I need to retract Issue 2 — I re-examined my JSONL files and agent_progress records are present on v2.1.71 on Linux too. My initial grep was against a session without sub-agents. Sorry for the false alarm.

So the only real problem is Issue 1. Looking at extension.js v1.0.2 more carefully, "Agent" needs to be added in 4 places, not just the 2 I originally mentioned:

Status generator — add case "Agent": before case "Task":
Progress handler filter — accept both "Task" and "Agent"
Tracked tool Set — new Set(["Task", "AskUserQuestion"]) should include "Agent"
Cleanup handler — o.activeToolNames.get(h)==="Task" should also match "Agent"
I had patched 1-2 locally but missed 3-4, which is why sub-agents still weren't showing up. Sharing this in case it saves you some time.

Environment:

Debian 6.1.0-41-amd64
Claude Code 2.1.71 via VSCode Remote SSH
Pixel Agents 1.0.2

[gaby]

@Revdep You are correct, the issue is the new name.

@pablodelucca any ETA for the next release? Thanks! 💪

[pablodelucca]

@gaby probably today or tomorrow!

[gaby]

@pablodelucca Thanks, looking forward 💪

[mattyx97]

@pablodelucca any eta?

[florintimbuc]

Fixed in v1.1.0! Sub-agent characters spawn correctly again. Update from the VS Code Marketplace or grab the .vsix from the latest release.

[gaby]

@florintimbuc @pablodelucca This is still not working. No matter how I launch the extension/claude it stays "idle".

I wonder if this PR is related to that #157

Notes:

OS: ubuntu 24.04
Claude: Binary installation (npm is deprecated)

• /home/user/.local/bin/claude
• /home/user/.claude/
  VSCode: Latest with latest extension.

When clicking [+agent] in the extension that claude terminal becomes extremely slow.

Steps:

• open vscode
• click extension
• click +agent
  • write a prompt like "help me understand this code".
  • i can see claude doing stuff and tool calling, but the pixel-agents extension stays "idle" and claude starts lagging heavily.

[Revdep]

same for me. if i click +agent and if i use from that agent a multi-agent plugin , like /pr-review-toolkit (6 agents), i can't see the agents at work in the map.

is it not supposed to work like that?