[BUG] Session exits silently with 'API Error: Out of memory' mid-turn on AWS Bedrock

[haulino]

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?

Claude Code session terminates unexpectedly mid-turn with no user-facing error message. The session was in the middle of an agentic loop (multiple sequential Bash tool calls) when it silently exited. The only evidence of the failure is visible in the .jsonl transcript file, where the final entries show:

"stop_reason": "stop_sequence"
"content": "API Error: Out of memory"

No error dialog, no warning, no graceful shutdown — the session just disappears.

What Should Happen?

Claude Code should catch the API Error: Out of memory response from Bedrock and surface it to the user with a meaningful message (e.g., "The session ran out of memory — try /compact to reduce context size and resume"). Silently exiting leaves the user with no indication of what happened or how to recover.

Error Messages/Logs

# From ~/.claude/projects/<project>/0a80a98a-2efd-473d-8988-80fe42db6e92.jsonl (tail)

{"type":"assistant","message":{"role":"assistant","stop_reason":"stop_sequence","content":"API Error: Out of memory"}}
{"type":"system","subtype":"turn_duration",...}
{"type":"last-prompt",...}
{"type":"permission-mode",...}

No Stop hook fired, confirming the exit was not a clean/graceful shutdown.

Steps to Reproduce

1. Start a Claude Code session on AWS Bedrock with a multi-step agentic task
2. Run a long sequence of tool calls (15+ turns) that accumulate significant context (~280KB transcript)
3. Observe: session exits silently mid-turn with no error shown to the user
4. Check the .jsonl transcript at ~/.claude/projects/<project>/<session-id>.jsonl — the final entry will show stop_reason: stop_sequence and content: API Error: Out of memory

Claude Model

Sonnet (default) — us.anthropic.claude-sonnet-4-6

Is this a regression?

I don't know

Claude Code Version

2.1.116 (Claude Code)

Platform

AWS Bedrock

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

• Session ID: 0a80a98a-2efd-473d-8988-80fe42db6e92
• Transcript size at exit: 284KB
• Region: us-west-2
• A prior session in the same project (e49fb48f) was 1.2MB and completed normally — the OOM occurred in a smaller subsequent session, suggesting it may be request-size related rather than cumulative transcript size
• Session logging hooks (SessionStart / Stop) were added after this incident; the missing Stop hook entry confirmed the exit was ungraceful
• A duplicate issue was filed before discovering the template: [BUG] Session exits with 'API Error: Out of memory' mid-turn on Bedrock (stop_sequence) #51754 (being closed in favor of this one)