diff --git a/engines/tortoise/exclusive-gpu.sh b/engines/tortoise/exclusive-gpu.sh
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+#!/bin/bash
+# Tortoise GPU exclusivity wrapper. The 2070 Super (8GB) can't host
+# F5 (~4.5GB) + Kokoro (~2.7GB) + Tortoise (~5GB peak) simultaneously,
+# so we stop the other two engines for the duration of a Tortoise run
+# and restart them after.
+#
+# Usage:
+#   exclusive-gpu.sh <command...>
+#
+# Example:
+#   exclusive-gpu.sh docker exec skald skald narrate --chapter <uuid>
+#
+# Exits with the wrapped command's status. Restarts the engines
+# regardless of success/failure (trap on EXIT).
+set -euo pipefail
+
+STOP_ENGINES=(f5-tts kokoro)
+
+cleanup() {
+    local rc=$?
+    echo "[exclusive-gpu] restarting engines"
+    for engine in "${STOP_ENGINES[@]}"; do
+        docker start "$engine" >/dev/null 2>&1 || \
+            echo "[exclusive-gpu] failed to restart $engine — investigate"
+    done
+    return "$rc"
+}
+trap cleanup EXIT
+
+echo "[exclusive-gpu] stopping engines: ${STOP_ENGINES[*]}"
+for engine in "${STOP_ENGINES[@]}"; do
+    docker stop "$engine" >/dev/null 2>&1 || true
+done
+
+# Restart Tortoise to clean up any cached GPU allocations from the
+# now-stopped engines (their CUDA contexts can linger briefly).
+docker restart tortoise >/dev/null
+echo "[exclusive-gpu] waiting for tortoise healthz..."
+for i in {1..30}; do
+    if curl -sf http://192.168.0.5:7795/healthz | grep -q '"loaded":true'; then
+        break
+    fi
+    sleep 2
+done
+
+echo "[exclusive-gpu] running: $*"
+"$@"
diff --git a/engines/tortoise/hacks.md b/engines/tortoise/hacks.md
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+# Tortoise engine — kludges branched off main
+
+This branch carries the engine-specific tweaks that don't generalise
+to F5 / Kokoro. Tortoise is the audiobook-quality engine but the
+trade-offs are real and need explicit handling — speed and GPU.
+
+## 1. GPU exclusivity
+
+**File:** `exclusive-gpu.sh`.
+
+The 2070 Super has 8GB. F5 (~4.5GB) + Kokoro (~2.7GB) + Tortoise
+(~5GB peak) sums to ~12GB — over budget. First Tortoise smoke
+caught it: `torch.OutOfMemoryError: ... 9.31 MiB is free`.
+
+Solution: stop the other two engines for the duration of a Tortoise
+run. The script wraps any command, stops `f5-tts` + `kokoro`,
+restarts `tortoise` to clean its CUDA context, waits for healthz,
+runs the wrapped command, then restarts the engines on EXIT trap
+(success or failure).
+
+```bash
+./exclusive-gpu.sh docker exec skald skald narrate --chapter <uuid>
+```
+
+Remove when: GPU upgrade (P40 24GB / 3090 24GB / etc) lets all three
+engines co-reside.
+
+## 2. Speed — slow, batch-only
+
+Tortoise at `standard` preset is **~74x slower than real-time** on
+the 2070 Super (smoke: 6.5s of audio took 478s wall clock). A 33-min
+Chapter 2 render would take ~8 hours. Tortoise is acceptable for
+overnight batched runs but NOT interactive rendering.
+
+Quality presets and their approx wall-clock for a 3000-word chapter:
+- `ultra_fast` — ~1h, noticeable quality drop
+- `fast` — ~2h
+- `standard` — ~6-8h, the recommended bar
+- `high_quality` — ~24h, marginally better than standard
+
+For most use, `standard` is right. Reserve `high_quality` for
+short prologues or named samples.
+
+## 3. Voice mapping format
+
+Tortoise's voice roster (`lj`, `freeman`, `daniel`, etc.) lives
+behind `source='tortoise_tts'` in the `voices` table. Character
+slug → Tortoise voice mapping is independent of the Kokoro mapping
+— a story can have BOTH a Kokoro and Tortoise mapping live in
+parallel, picked at render time via story.preferred_voice_id or
+the --voice flag.
+
+Tortoise voices may sometimes warble or stutter at chunk boundaries
+— the `tortoise.api.TextToSpeech.tts_with_preset` call is per-chunk
+and re-conditions the voice each time. Acceptable for v0.1; future
+work could feed `conditioning_latents` directly for tighter cohesion.
+
+## 4. No respelling overrides for Tortoise (yet)
+
+The `pronunciation_overrides` rows in the DB are seeded with
+lowercase-syllable respellings tuned for Kokoro's misaki tokenizer.
+Tortoise uses a different phonemizer (`g2p_en`) which handles many
+of those proper nouns better natively — but some still mangle.
+
+For now, narrate's substitution applies the same overrides regardless
+of engine, which means Tortoise sees `prip-yat` for "Pripyat" — same
+input, different phonemizer interprets differently. Usually OK but
+audit after each batch.
+
+Future: per-engine override sets, OR an `engine` column on
+pronunciation_overrides.