Two clients on one Square location double a day's tender in the window
between deploying and finishing the migration. Reproduced end to end:
1. charge X carries the legacy key square/charge/P and belongs to
client B's order
2. client A's payout import resolves X through existing-id's legacy
fallback and renames it into A's scope
3. client B's next order import matches neither scheme, so it mints a
second charge
4. :sales-order/charges is cardinality-many and orders transact as
plain maps, so nothing retracts the first
B's order ends up holding two charges for one payment — $200 of tender
for a $100 payment — and running the migration on that state produces
square/charge/BBB-LB-AAA-LA-P, the same double-scoped shape that already
doubled tender on five clients once during this work.
existing-id's legacy branch now declines any record already owned by a
different client, reading the owner attribute and, for charges that
predate :charge/client, the client of the referencing order. Declining is
also correct on its merits: the write then lands on this client's own
copy, which is what the scoped keys exist to create. The payout path also
writes :charge/client/:charge/location alongside the key, so a charge's
scope and its owner can no longer disagree.
The guard is transitional and gets deleted with the legacy branch it
protects, at rollout step 9.
Rollout resequenced for the decision to leave duplicate client records
active: no deactivation, no "which record survives" call, and the risk
window closed by pausing the importer across deploy + migrate rather than
by removing one of the two writers. Both records converge to independent
stable histories once every key carries its owner.
Also from review:
- migrate-all! now collision-checks the charge pass like the other three
attributes instead of discovering a clash mid-run over 17M rows
- split-and-rekey-charges! logs progress every 200 batches; an
interrupted 19M-order run left no trail
- unscoped-report's docstring no longer promises a zero its :no-owner
column cannot reach; plan is named as the authoritative signal
- the rollout's pre-flight asked for a :collisions key plan never
returns, so it silently passed on every database
- the multi-parent gate sampled (take 400000 (all-order-ids db)), which
streams :aevt — ascending entity id — and so read the OLDEST 2% of
orders: 2019-12-31 to 2021-06-03, before any of the contention it
looks for. Now every order of the last year via the client+date index,
5,159,787 on the restored copy, reading 0
- the report claimed same-client pairs get copied once batches split
them. They do not, at any batch size; verified at batch-size 1 and now
pinned by a test
30 tests, 72 assertions.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Bryce
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