[BUG] Claude Code fell down (API Error: 400) and can't get back up

Environment

• Platform (select one):
• [X] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: 1.0.18 (Claude Code)
• Operating System: macOS 15.3
• Terminal: IntelJIdea

Bug Description

Claude was working on some code, when it got an error:

  ⎿ API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"The request body is not valid JSON: no low surrogate in string: line 1 column 78532 (char 
    78531)"}}

As I have done previously, I told the tool to "continue", and the same error repeats.

> Continue, you hit a tools error I think.
  ⎿ API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"The request body is not valid JSON: no low surrogate in string: line 1 column 78495 (char 
    78494)"}}

Steps to Reproduce

1. Tell Claude to perform a task
2. Claude crashes with API error 400
3. Tell Claude to continue
4. Error repeats

Expected Behavior

1. API:400 not to happen
2. continue to work

Actual Behavior

1. API:400 happened
2. continue did not work