docs(zonos-gateway): capture the live :8890 gateway stack + emotion-preset system

Captures the production Zonos TTS path that the repo was blind to: stock ZONOS2
:1920 engine (stacks/zonos-engine) fronted by zonos-gateway:0.2.0 :8890, reached
via the LiteLLM ext-tts alias. Documents the emotion-preset system (neutral/warm/
excited/sad/intense/whisper, the simple preset: caller path), the API, and the
measured real-time cost (calibrated steering free at RTF~0.52, cfg1.5 ~0.625 —
still realtime). Flags the gateway source (~/zonos-gateway on irv-ml1) as not yet
in gitea. Marks stacks/zonos (v0.1 Gradio) dead/superseded. Records the emotion-
lever finding (text-priming flat -> native steering works) in persistent memory.

persistent-memory.md

@@ -130,6 +130,8 @@ _As of 2026-07-17 — active work is CONTAINERIZING the Zonos2 TTS engine + prot
 
 ## Recent decisions
 
+- `[2026-07-17]` **Zonos emotion levers RESOLVED: text-priming is FLAT → the working lever is ZONOS2's native emotion-steering, which the gateway ALREADY exposes as presets.** The prosody-priming A/B (prime→generate→excise, silence-gap cut, parakeet-validated) was operator-judged FLAT on this checkpoint — text doesn't move it. Native `emotion_directions/` (happy/sad/angry/surprised + valence/arousal axes, per-speaker calibrated for AmericanFemale/Male/British) clearly WORKS (sad→slow/quiet, excited→fast/bright, etc.). **`zonos-gateway:0.2.0` (:8890) already wires it**: simplest caller path = `POST /v1/audio/speech {preset:"…"}` — presets neutral/warm/excited/sad/intense/whisper (defined in `~/zonos-gateway/src/zonos_gateway/dials.py`), reached via the **LiteLLM `ext-tts` alias** (engine-neutral swap point; consumers never call the gateway by name). RTF measured on 3090: cfg1.0 steering = FREE (~0.52 = neutral, additive vectors), cfg1.5 amplified ~0.625 (~+20%, still realtime). Captured the live gateway stack → `stacks/zonos-gateway/` (compose+env+README); ⚠️ gateway SOURCE at `~/zonos-gateway` on irv-ml1 is NOT in gitea (backup gap, follow-up); `stacks/zonos` (v0.1 Gradio) marked DEAD/superseded. Whisper is a composed preset (no whisper *direction*; escalation for hard affects = custom directions via `scripts/build_emotion_directions.py` or emotional-ref cloning `speaker_audio_base64`). Harnesses in scratchpad (not yet landed). [[reference_zonos_tts_stack]]
+
 - `[2026-07-17]` **Zonos2 :1920 → self-contained container (stays on 3090); prosody-priming is adapter-level, engine stays stock.** Config captured (14a0004, unpushed); build = cu128 base + `uv sync` vs the lock + weights mount; priming = prime→generate-one-utterance→parakeet-clip→deliver in the gateway adapter. Crux = does AR prosody carry the sentence boundary (A/B the join). → `persistent-memory.d/2026-07-17-zonos2-containerize-prosody-priming.md`
 
 - `[2026-07-16]` **GPU re-org: char-rp→GPU1 + both cards re-optimized for max context.** Moved char-rp (Magidonia-24B) GPU0→GPU1, then maxed context: char-rp-reasoning 150K→256K (util 0.46, 1.56x), gen→256K + seqs 16→32 (util 0.42, 5.43x), granite 64K→**128K full-chapter** (util 0.27, 1.50x). FINAL: GPU0 ~14 G reserve (both seats 256K native), GPU1 ~6.7 G headroom. All healthy. LESSON: KV must hold ≥1× max-len (util-floor crashes) + per-model KV cost varies ~8× (MoE cheap, dense pricey) → tune util empirically. See Current state for the full layout + backups.