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The backfill window: a Stage 1 write after Deploy 1, read by a naive Stage 3
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captured: 2026-09-16T19:20:56.276837493Z


-- the row a lingering Stage 1 instance just wrote --
[{NAME=Katherine Johnson, EMAIL=katherine@example.test, EMAIL_ADDRESS=null}]

-- a NAIVE Stage 3 read (email_address alone) - the bug --
naive Stage 3 email column value: null

-- the SHIPPED Stage 3 read (CustomerService, COALESCE) - the fix --
CustomerService (stage 3) result: Optional[Customer[id=1, name=Katherine Johnson, email=katherine@example.test]]