Root cause of "engine 'nvidia' not responding" during generation: in --debug
mode the streaming response generator print()s the ENTIRE generated text (raw
+ repr), and a prompt-echoing/runaway generation makes that multi-MB. The
engine writes stdout to a pipe drained by the front; once the pipe fills, that
synchronous print() — running on the event-loop thread inside the SSE generator
— BLOCKS, freezing the engine so health polls time out and the front flips it
to "not responding" (seen ~3s into each debug flood in debug.log).

- api/text.py: add _clip_for_log() and bound every large debug/dump print
  (generated_text, second_pass/reasoning/final text, formatted_response,
  extracted_tool_calls) to ~4KB head+tail. Shared layer, so both engines covered.
- engine_supervisor: enlarge each engine's stdout pipe to 1 MiB (F_SETPIPE_SZ)
  so bursts can't stall the event loop even if the pump lags briefly.

Also: name processes by role — coderai-front for the front, coderai-<name> for
each engine (CODERAI_ENGINE_NAME passed at spawn), coderai for single-process.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011DDv7BchtZQWsnPG6Jm49m