-- +goose Up

-- The book's pipeline SHAPE — does its work go through an editor — becomes two facts instead of one,
-- because the single fact was answering two different questions and could only be right for one.
--
-- `books.edit_wave` (00024) stays exactly as it is, monotone, and keeps its pin (D39.153 §4б): it is
-- the HISTORICAL fact, "has this book ever been through an editing pipeline", and monotonicity is what
-- stops a half-edited chapter counting as finished. What it is NOT, and was being used as, is the
-- authority on how the book's LIFETIME count is computed. Read that way it is wrong in both
-- directions, and both were open register rows:
--
--   PD-403, editor REMOVED — the flag cannot come back down, so the count stays pinned to an edit
--   column no run will ever fill: the book freezes half-done, the run closes `ready` at 50%, and the
--   purchase scale goes on offering chapters that are already translated. The user is sold work twice.
--
--   PD-404, editor ADDED — the flag flips true on the first progress event of the run, the count moves
--   to the edit column mid-transaction, and a book showing 7/10 shows 0/10, backwards, inside one
--   `structure_version`, which the canon forbids in as many words.
--
-- The owner ruled on 28.08 (D39.165 §2): a change of pipeline shape is an EVENT OF THE BOOK, like
-- cutting it again, and the count is legitimately RECOMPUTED when the boundary is crossed. So the
-- boundary needs a carrier, and this is it.
--
--   `epoch_editor` — the shape of the CURRENT epoch, ASSIGNED rather than accumulated. NULL until the
--   engine has announced a shape at all; from then on it is what the engine last said. This is what
--   the lifetime count reads.
--   `shape_epoch` — how many boundaries this book has crossed. It is a COORDINATE, like
--   `structure_version`: a client tells "the count was legitimately recomputed" from "the count moved
--   backwards illegally" by seeing it change. It is the only half of this pair that goes on the wire,
--   and it goes as an OPAQUE counter (canon 0.9.0): the shape itself — whether this book gets an
--   editing pass — is NOT published, because the canon's boundary forbids the wire everything about
--   HOW a book is translated (§Boundaries: names of models, phases and stages, internal vocabularies,
--   sums of money). D39.163 granted that boundary its SECOND exception, `Progress.stage`, under two
--   stated conditions; an opaque generation counter needs no exception at all, which is why this
--   column is one.
--
-- Backfill: every existing book gets epoch 0 and its CURRENT flag as the epoch's shape, so nothing
-- moves on deployment — the first announcement that DIFFERS is the first boundary. Books that never
-- announced (edit_wave IS NULL) stay NULL and keep falling back to the flag's own default.
alter table books
    add column shape_epoch integer not null default 0,
    add column epoch_editor boolean;

update books set epoch_editor = edit_wave where edit_wave is not null;

-- ⚠ 00024's header comment describes the frozen rule this migration supersedes, and it is IMMUTABLE
-- (released migrations are append-only, TestReleasedMigrationsAreUnchanged). It is corrected here
-- rather than there: the monotone flag it introduced is still correct for the question IT answers.

-- +goose Down
alter table books drop column epoch_editor, drop column shape_epoch;