[BUG] Credits consumed but messages not processed — billing error

Description

All credits were fully consumed by Claude but ZERO response was delivered to the user. The only message received was:

"Your previous message was not sent. You can try again"

Steps to reproduce

1. User sent a message to Claude via web chat at approximately 19:40
2. Credits were completely deducted from the account
3. No actual response was delivered — only the error message above
4. All credits gone with no valid output received

Environment

• Platform: Web (claude.ai chat)
• Account type: Claude Pro
• Model: Claude Opus 4.8

Expected behavior

• If credits are consumed, a valid response should be delivered
• Or: if a response cannot be delivered, credits should NOT be consumed

Additional context

This is a clear billing error: full consumption of credits with ZERO response delivered to the user. Only a system error message was shown with no actual Claude output.

Per Anthropic Consumer Terms of Service (effective October 8, 2025), billing errors that affect credits are eligible for remediation. Credits should be refunded since no service was rendered.