The `RichLogHandler` introduced in livekit-agents 1.3.x causes regressions on termination signals when stdout is piped

[zaheerabbas-prodigal]

Bug Description

The RichLogHandler introduced in livekit-agents 1.3.x causes two regressions when stdout is piped (e.g., python main.py dev | tee log.txt):

1. No colored output - Rich's TTY detection disables colors when piping
2. Ctrl+C hangs - BrokenPipeError during shutdown prevents graceful termination

Both worked correctly in 1.2.17.

Expected Behavior

• Colored log output (as in 1.2.17)
• Ctrl+C gracefully terminates the process

Reproduction Steps

# Run agent with piped output
python main.py dev | tee -a debug.log

# Press Ctrl+C to stop
# Result: Process hangs, no colors in output

Operating System

macOS Tahoe

Models Used

Deepgram Nova-3, Cartesia

Package Versions

livekit==1.0.23
livekit-agents==1.3.10
livekit-api==1.0.7
livekit-blingfire==1.1.0
livekit-plugins-anthropic==1.3.10
livekit-plugins-cartesia==1.3.10
livekit-plugins-deepgram==1.3.10
livekit-plugins-elevenlabs==1.3.10
livekit-plugins-google==1.3.10
livekit-plugins-noise-cancellation==0.2.5
livekit-plugins-openai==1.3.10
livekit-plugins-silero==1.3.10
livekit-plugins-turn-detector==1.3.10
livekit-protocol==1.1.1

Session/Room/Call IDs

Local dev environment

Proposed Solution

Additional Context

Issue 1: No Colors

Rich checks sys.stdout.isatty() which returns False when piping. This disables all color output.

Issue 2: Ctrl+C Hangs

When Ctrl+C is pressed while piping:

1. SIGINT sent to process group
2. tee may terminate first, breaking the pipe
3. Rich attempts to write to broken pipe
4. Rich's on_broken_pipe() raises SystemExit(1) (rich/console.py:1305)
5. This corrupts the shutdown sequence, causing hang

Traceback:

File ".../rich/console.py", line 1290, in _write_buffer
    self.file.write(text)
BrokenPipeError: [Errno 32] Broken pipe

During handling of the above exception, another exception occurred:
...
File ".../rich/console.py", line 1305, in _write_buffer
    raise SystemExit(1)
SystemExit: 1

Screenshots and Recordings

No response