[BUG] Conversation chain breaks mid-session - earlier messages lost on resume

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?

After resuming a session, earlier messages in the conversation are missing. The model cannot see or recall those messages, even though they exist in the transcript file.

User experience:

• Normal conversation, no special actions taken
• Later, /exit and resume
• Upon resume, only a portion of the conversation is visible
• The model has no memory of the earlier parts

Observed in transcript:

• All messages exist in the .jsonl file
• However, one message's parentUuid references a UUID that does not exist in the transcript
• This breaks the conversation chain: messages before the break are orphaned
• On resume, only messages after the break are loaded

Example from my transcript:

• Line 104 (04:55:11): assistant message, uuid d861cd0f-...
• Line 105: file-history-snapshot
• Line 106 (04:57:22): user message, uuid 55709a47-..., parentUuid 7a299ae8-... ← does not exist

The parentUuid 7a299ae8-... is not found anywhere in the transcript. It appears a message was generated internally but never written to the transcript, breaking the chain.

What Should Happen?

All messages should be properly linked via parentUuid, and the full conversation should be restored on resume.

Error Messages/Logs

No error messages. The conversation silently loses its earlier context.

Steps to Reproduce

Unfortunately, I cannot reliably reproduce this. It happened during normal usage:

1. Start a session, have a conversation
2. Continue using Claude normally (tool calls, responses, etc.)
3. At some point, /exit and later resume
4. Observed: Part of the conversation is missing
5. Inspect transcript: A message references a non-existent parentUuid, breaking the chain

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.23 (Claude Code)

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

The file-history-snapshot at line 105 has messageId matching line 106's uuid, suggesting it was created at the same time. The issue seems to be that an intermediate message (uuid 7a299ae8-...) was never written to the transcript.

Key distinction from similar-sounding issues:

• This is NOT about sessions disappearing from /resume list (sessions are visible and resumable)
• This is NOT about losing recent/latest messages (the earlier messages are lost, not the recent ones)
• This is about a broken parentUuid chain within a single session, causing the first part of the conversation to become unreachable

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✍️ Author: Claude Code (Dev Container) with @carrotRakko

Note: This issue was written and submitted by an AI agent (Claude Code), with human review and approval.