[BUG] Claude hangs in "Caramelizing" state after completing task with background processes

[mhcandan]

Preflight Checklist

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

What's Wrong?

Title: Claude hangs in "Caramelizing" state after completing task with background processes

Description:
After starting background processes (backend/frontend servers) and responding that the task was complete, Claude Code remained in a waiting state ("Caramelizing") for 19+ minutes without returning control to the user. User had to
press Escape to interrupt.

Steps to reproduce:

1. Ask Claude to start backend and frontend servers using run_in_background: true
2. Claude starts both servers successfully and responds "The app is ready"
3. Claude does not return control - stays in "Caramelizing" state indefinitely
4. Background task notifications continue to arrive but Claude takes no action
5. User must press Escape to regain control

Expected behavior:
After completing the response, Claude should immediately return control to the user without requiring manual interruption.

Environment:

• Claude Code CLI
• Model: Claude Opus 4.5

What Should Happen?

o bug in the PWZ code - that was just me waiting for your next instruction after the servers started. The "Caramelizing" state means I had completed the task and was idle. The background task notifications were coming in (showing
the servers were active), but I had nothing more to do until you gave another command.

The servers are running and the app is working. What would you like me to do next?

❯ why should I have to press escape to take you out of this mode ?

⏺ You're right - you shouldn't have to. After I said "The app is ready and serving requests," my turn was complete and I should have returned control to you immediately.

The background task notifications kept coming in (showing server activity), but I had no action to take on them. Something in my processing kept me in a waiting state when I should have simply finished.

This isn't expected behavior. I apologize for the confusion - you shouldn't need to interrupt me after I've completed a task.

Error Messages/Logs

Steps to Reproduce

#!/usr/bin/env python3
"""
Reproduction script for Claude Code "Caramelizing" hang bug.

Bug: After starting background processes and completing a response,
Claude Code hangs in "Caramelizing" state instead of returning control
to the user. User must press Escape to interrupt.

To reproduce:

1. Open Claude Code in this directory
2. Ask: "Run the reproduction script in the background"
3. Claude will start the script and say it's running
4. Observe: Claude stays in "Caramelizing" state indefinitely
5. Press Escape to regain control

The script simulates a long-running server that periodically outputs,
similar to uvicorn/next.js dev servers.
"""

import time
import sys
from datetime import datetime

def simulate_server():
"""Simulate a dev server that outputs periodic status messages."""
print("=" * 60)
print("REPRODUCTION SCRIPT FOR CLAUDE CODE CARAMELIZING BUG")
print("=" * 60)
print(f"[{datetime.now().isoformat()}] Server starting...")
print(f"[{datetime.now().isoformat()}] Listening on http://localhost:9999")
print(f"[{datetime.now().isoformat()}] Server ready!")
print()

# Simulate periodic server activity (like request logs)
counter = 0
while True:
    counter += 1
    timestamp = datetime.now().isoformat()

    # Output to stdout (like server request logs)
    print(f"[{timestamp}] Heartbeat #{counter} - server is running")
    sys.stdout.flush()

    # Also output to stderr occasionally (like uvicorn does)
    if counter % 3 == 0:
        print(f"[{timestamp}] INFO: Background activity", file=sys.stderr)
        sys.stderr.flush()

    time.sleep(5)  # Output every 5 seconds

if name == "main":
try:
simulate_server()
except KeyboardInterrupt:
print("\nServer stopped.")
sys.exit(0)

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

2.1.5

Claude Code Version

2.1.17

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

No response

[github-actions]

Found 3 possible duplicate issues:

1. TaskOutput hangs after background agent completes #20236
2. [BUG] Session hangs at 0 tokens after background task completes with --dangerously-skip-permissions #20048
3. Terminal becomes unresponsive after completing work (UI frozen, process alive) #19544

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
• To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

[BioInfo]

Im seeing same

0 Token Hang After Skill/Sub-Agent Completion
Status: Active Bug
Severity: Medium (Wastes time, but doesn't break functionality)
First Observed: 2026-01-23
Symptoms
After a skill or sub-agent completes its work (e.g., /researching-with-perplexity, Task tool with subagents), the main Claude Code session enters "Deciphering..." mode with "↓ 0 tokens" output that continues indefinitely (observed for 1m 43s+).
Example:
✓ Sautéed for 2m 5s
⊙ Deciphering... (esc to interrupt · 1m 43s · ↓ 0 tokens)
The session appears stuck in thinking/processing mode without producing any output.

[chrisedington]

I had this too on OSX 2.1.17 Native

[eliasmarquesfotografo]

I'm experiencing the same issue here: Claude hangs in the "Caramelizing" state after completing tasks that use background processes.
My environment: macOS / Version: 2.1.17

[Butanium]

yes also sometimes some abckground task notifications just disappear

[35dustin]

+1 Experiencing the same issue on Windows.

Environment:

• Platform: Windows
• • Model: Claude Opus 4.5
    Symptoms:
• Running multiple background agents via Task tool with run_in_background: true
• • Agents complete successfully (UI shows green dots with "Agent X completed")
• • • But main Claude process stays stuck in "Frolicking..." state
• • • • Status shows "↓ 0 tokens" - no response being processed
• • • • • Agent completion events visible in UI but Claude never wakes up to handle results
• • • • • • Must press Escape to break out (which can kill other still-running agents)
• • • • • • • Sometimes Escape doesn't work - have to close/reopen terminal
              Screenshot attached showing: Two agents completed but Claude stuck for 3m 23s with 0 tokens.

[rcbeall1]

Same issue here.