Description

Verbose command output from long-running processes (e.g., Kopia backup progress) can overwhelm a Claude Code session, causing the interface to lock up and consuming excessive tokens.

Steps to Reproduce

1. Run a backup command (e.g., kopia snapshot create) that outputs continuous progress updates
2. The terminal floods with thousands of lines like:

   hashing, 8429 hashed (673.9 MB), 0 cached (0 B), uploaded 473.0 MB, estimating...
   

3. Session becomes unresponsive; keyboard input locks up
4. Token usage spikes significantly from processing all the output text

Expected Behavior

• Output should be rate-limited, truncated, or buffered to prevent session lockup
• Warning when command output exceeds a threshold
• Token consumption should be bounded for command output

Actual Behavior

• Session locks up completely
• All output text is processed, consuming tokens
• User must force-quit or switch to another terminal

Environment

• macOS (Darwin 25.2.0)
• Claude Code CLI
• Model: claude-opus-4-5-20251101

Workaround

Redirect verbose command output to a file:

command > /tmp/log.txt 2>&1 &

Suggestion

Consider implementing:

1. Output truncation after a configurable threshold
2. A warning when output volume is high
3. Documentation noting the risk of verbose commands in-session