diff --git a/stacks/skaldsong/compose.yaml b/stacks/skaldsong/compose.yaml
index 116c129..523a0c0 100644
--- a/stacks/skaldsong/compose.yaml
+++ b/stacks/skaldsong/compose.yaml
@@ -73,6 +73,14 @@ services:
       SKALDSONG_TTS_ENGINE: "${SKALDSONG_TTS_ENGINE:-kokoro}"
       SKALDSONG_TTS_BASE_URL: "${SKALDSONG_TTS_BASE_URL:-http://10.100.79.3:8193}"
 
+      # VibeVoice secondary TTS engine (issue #73, added 2026-05-27).
+      # Same fleet (irv-ml1) as Kokoro, separate port 8194. Encode-once
+      # batch-synth path (long-form bedtime narration); SPA shows a
+      # second "encode with vibevoice" row below the Kokoro playback bar.
+      # Empty/unset → feature stays dormant (routes 404, SPA button hidden).
+      SKALDSONG_TTS_VIBEVOICE_BASE_URL: "${SKALDSONG_TTS_VIBEVOICE_BASE_URL:-}"
+      SKALDSONG_TTS_VIBEVOICE_DEFAULT_VOICE: "${SKALDSONG_TTS_VIBEVOICE_DEFAULT_VOICE:-fable}"
+
       # SPA static assets — baked into the image at /app/spa by the
       # Dockerfile's web-builder stage (COPYs the SvelteKit build output
       # flat into /app/spa, not into /app/spa/dist).