Queued/pending user input silently lost while agent is working

Description

When I send a message while the agent is still working (a queued/pending message), the input sometimes gets lost. The message disappears from the prompt as if it's been queued for processing, but when the agent finishes its current turn, it has no awareness of what I said. The queued message is effectively dropped with no indication that anything went wrong.

This does not happen when the agent is idle and ready for input - only when queuing a message during an active agent turn.

Environment

• Claude Code version: 2.1.17
• OS: macOS 15.6.1

Expected behavior

Queued messages should be reliably delivered to the agent once it completes its current turn, or an error should be shown if the message cannot be queued.

Actual behavior

The queued message is consumed (removed from input) but the agent never receives or acknowledges it when it finishes working. No error is displayed.