Verbose roleplay-tuned narrators (Cydonia, Magnum, etc.) reliably
ignore prompt-level beat-count instructions and ramble for 6-12
asterisk-action beats per turn — even with HARD CAP language and
worked examples in the closing instruction. The fix is a deterministic
post-stream trimmer:
- New trim_to_max_beats(text, max_beats) in chat/services/prompt.py.
Counts * characters in the streamed output (each beat = 2
asterisks: open + close), trims at the start of the (max_beats+1)th
asterisk action, strips trailing whitespace. Idempotent and safe
on under-cap input.
- Wired into post_turn for both the primary stream (3-beat cap) and
the optional interjection stream (2-beat cap — interjections are
by definition shorter chime-ins).
- Tightened the closing instruction: explicit "HARD CAP: 2-3 beats"
with "After the third beat, STOP". Helps the well-behaved models
self-cap; the post-processor catches the rest.
- max_tokens: 250 -> 160 (lets the 3rd beat finish naturally before
hitting the physical cap; trim_to_max_beats handles 4+ beat
overflow). temperature: 0.85 -> 0.7 (Cydonia is more compliant
with format instructions at slightly cooler sampling).
- Test budgets bumped (closing grew ~15 tokens with the new wording).
6 new tests for trim_to_max_beats covering passthrough, exact-cap,
4-beat trim, 6-beat runaway, lower caps, zero cap.
Verified live: 4-turn bench against chat_maya, every response is
2-3 beats consistently. Suite: 470 passed in 11.7s.
Joseph Doherty
3b83786b8b