docs(reports): rerun the ninety-day reconciliation from a fresh restore

Rebuilt the whole analysis from nothing: fresh restore of backup point
209608347, deactivate the ten shared locations, re-key and split every
one of 19,040,785 orders, re-import from Square, then two full ninety-day
recomputes — one with the fixes off, one with them on.

The baseline is now a no-fix recompute rather than production's stored
summaries. That is the stricter comparison: production's figures are in
places months stale, and crediting the fixes with repairing ordinary
staleness flattered them. On the fairer footing the two arithmetic fixes
are worth 979 client-days and $61,769.56, taking the window from 1,258
days out of balance ($69,560.10) to 279 ($7,790.54), with zero days
knocked out of balance and zero already-balanced days altered at line
level.

The migration now runs to completion database-wide: 17,047,142 payments
scoped, nothing left to rename, nothing unscopable, and no payment owned
by more than one order across 400,000 orders checked. The earlier
"transactor-bound, two days" diagnosis was wrong — the bottleneck was GC
in the driving process; the full pass takes about thirteen minutes.

Also corrects compare-sales-summaries: :ledger-mapped/amount, ledger-side
and account are :db/noHistory, so as-of cannot recover past amounts and
a rewritten summary reads back as a false balanced day. Every figure in
the report comes from live captures taken straight after each pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/clj/auto_ap/jobs/compare_sales_summaries.clj

@@ -1,14 +1,25 @@
 (ns auto-ap.jobs.compare-sales-summaries
   "Compares sales summaries between two points in the same database.
 
-  Datomic keeps every past value, so a recompute can be audited against exactly what was there
-  before by reading `(d/as-of db t)` for some earlier `t` — no snapshot or scratch copy needed.
-
   The question this exists to answer is narrower than \"did the totals improve\": it is *which
   days changed, and were any of them already balanced*. A day that was balanced before and still
   balances after can still have had its line amounts move, and that is a real change to the
   books even though no red turns green. Counting only balanced/unbalanced transitions would hide
-  it entirely."
+  it entirely.
+
+  DO NOT USE `compare-against` — OR ANY `d/as-of` DATABASE — TO COMPARE AMOUNTS. The obvious
+  reading is that Datomic keeps every past value, so a recompute can be audited against what was
+  there before with no snapshot. That does not hold here: `:ledger-mapped/amount`,
+  `:ledger-mapped/ledger-side` and `:ledger-mapped/account` are all `:db/noHistory true`, so
+  superseded values are discarded rather than retained. A summary that has since been recomputed
+  reads back through `as-of` with its categories intact and its amounts *absent* — which is
+  indistinguishable from a legitimate all-zero day, and quietly turns every rewritten summary
+  into a false \"was balanced, still balances\".
+
+  To compare amounts, capture `summaries-in` from a live `(d/db conn)` immediately after each
+  run, keep the two captures outside the database, and diff those. `compare-window` is safe when
+  both arguments are live database values; only the historical read is unsound. Categories and
+  which-days-changed do survive `as-of`, since `:sales-summary-item/category` retains history."
   (:require
    [auto-ap.datomic :refer [conn]]
    [auto-ap.datomic.sales-summaries :as d-ss]
@@ -119,7 +130,11 @@
          (into {}))))
 
 (defn compare-against
-  "Convenience: compare the current database against its own past value at basis `t`."
+  "Compare the current database against its own past value at basis `t`.
+
+  UNSOUND FOR AMOUNTS — see the namespace docstring. The amount, side and account attributes are
+  `:db/noHistory`, so any summary rewritten since `t` reads back with no amounts and appears
+  balanced. Kept only for comparing categories and identifying which days changed."
   [t start end]
   (let [db (dc/db conn)]
     (compare-window (dc/as-of db t) db start end)))