[BUG] Everything stopped working today

Environment

• Platform (select one):
• [x] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: 1.0.53
• Operating System: macOS 15.5
• Terminal: Terminal App

Bug Description

• Sometimes the task fails with "Error: Agent 1: Last message was not an assistant message"
• Other times it just stops working after a message when in between a task, prompts sometime work most of the time do nothing (no response from the model)

Steps to Reproduce

1. Try any prompt

Expected Behavior

Agent runs and finishes the task

Actual Behavior

Agent just stops working after a message or without a response

Additional Context

<img width="433" height="251" alt="Image" src="https://github.com/user-attachments/assets/c735520c-ad14-42a3-a55e-690a091019e5" />