Extension silently cuts a prompt over 50,000 characters and keeps no copy of the full text

What happened

I sent one long prompt in the Claude Code extension chat panel. It was a large pasted block with instructions I had typed after it, more than 50,000 characters in total.

The message was cut at 50,000 characters. Everything after that point never reached the model, and this line was added in its place:

[Message truncated - exceeded 50,000 character limit]

I did not notice any warning before or after sending. I only found out because Claude told me the request itself was missing. My typed instructions came after the pasted block, so all of them were lost. That was about 35 minutes of writing.

The full text cannot be recovered

• The session transcript (~/.claude/projects/<project>/<session>.jsonl) holds only the truncated message: 50,110 characters, including the truncation note.
• No fuller copy exists anywhere else I could find: ~/.claude, the local Claude cache, the temp folder, or the editor's storage and logs.

So the cut happens before the message is saved, and the original text is gone.

What I expected

Any one of these would have prevented the loss:

1. Warn before sending when the input is over the limit, and let me shorten it, instead of cutting it.
2. Keep the overflow and hand it to the model as an attachment it can read.
3. Save the full original text on disk (in the transcript or a paste cache) so it can be recovered.

At the very least, the chat panel should show clearly, at the moment of sending, that the message was cut and where.

Steps to reproduce

Taken from the incident. I have not re-run them.

1. Open the Claude Code chat panel in the extension.
2. Paste more than 50,000 characters into the input, then type an instruction after the pasted text.
3. Send.
4. The model receives only the first 50,000 characters plus the truncation note. The typed instruction is gone, and the saved transcript holds only the truncated text.

Environment

• Claude Code extension 2.1.296 (entrypoint: claude-vscode), running in Cursor
• Windows 11 Home 10.0.26200