-- Annotated TTS variant of each chapter's prose. NULL = not yet
-- generated; renderers fall back to body_md when this is NULL.
-- Otherwise this column carries the same prose with control tags
-- inline: [pause:Xs] / [breath] / [scene] — the kokoro server
-- interprets these into silence beats during synth.
--
-- Why a separate column instead of mutating body_md: the human-
-- readable version stays clean for web inspection + future plain-
-- text export. The TTS version is production output, regeneratable
-- whenever the author's beat-placement taste shifts.
ALTER TABLE chapters
    ADD COLUMN IF NOT EXISTS body_md_tts text;