[BUG] Background tasks (Agent/Bash) remain "Running" in Tasks panel after completion

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Description

When background agents or Bash commands complete, the Tasks panel continues to show them as "실행 중" (Running) with a green dot. They never transition to a completed/stopped state in the UI, even though the actual processes have finished and returned results.

Steps to Reproduce

1. Spawn 2+ background agents (run_in_background: true) that each execute multiple Bash commands
2. Wait for all agents to complete (completion notifications are received correctly)
3. Open the Tasks panel (작업)

Expected Behavior

Completed tasks should show as "완료됨" (Completed) or be automatically removed from the "실행 중" section.

Actual Behavior

10+ completed Bash tasks remain stuck in "실행 중" (Running) state indefinitely. Only manual dismissal (clicking X) clears them. The "완료됨" section correctly shows the parent Agent tasks, but all child Bash commands spawned by those agents stay in "실행 중".

Environment

• Claude Code Desktop App (Windows 11 Pro)
• Model: claude-opus-4-6[1m]
• Date: 2026-04-16
• Scenario: 2 background Opus agents, each running 15-30+ Bash/Read/Write tool calls

Screenshot

(Attach the screenshot showing 10+ tasks stuck as 실행 중)

<img width="1056" height="1113" alt="Image" src="https://github.com/user-attachments/assets/82d0a11b-e87b-4582-95fd-bbb1159fd2e9" />

What Should Happen?

완료 처리 되어야 함.

Error Messages/Logs

Steps to Reproduce

작업 진행 후 우측 패널에 작업 창을 열어두면 모두 실행중 상태로 계속 유지됨.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

버전 1.2581.0 (f10398)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_