[magnusp]

Closes #30. Part of #54.

What changed

• commit() and rollback() now delegate to one shared endTransaction path, matching xerial 3.53.4.0 SQLiteConnection.java:435-451.
• A StreamResult.Error from COMMIT/ROLLBACK, or a transport LibsqlException, is mapped to SQLException instead of being ignored.
• The baton is left in place when the transaction command fails, so the caller can retry against the same transaction stream.
• Added LibsqlConnectionTest covering server and transport failures for both COMMIT and ROLLBACK.
• Added a Toxiproxy integration test that breaks the connection during rollback(), asserts the SQLException, reconnects, retries the rollback, and verifies the insert was rolled back.

Contract decision

Parity with xerial 3.53.4.0: commit and rollback share one error path, a failed ROLLBACK throws, and transaction state is not cleared on failure.

Deviations

Transport-only: COMMIT/ROLLBACK is sent as its own pipeline request, and the stream Close is sent only after a successful transaction command. Sending Execute + Close in one pipeline would close the Hrana stream even when the command failed, so the driver could not preserve transaction state for a retry. The observable JDBC behavior matches xerial; the extra request is forced by the Hrana stream model.

Evidence

Failing before the fix (old LibsqlConnection):

$ ./mvnw -q -pl libsql-jdbc -am -Dtest=LibsqlConnectionTest -Dsurefire.failIfNoSpecifiedTests=false test
Tests run: 4, Failures: 4, Errors: 0, Skipped: 0
  serverErrorIsPropagatedAndTransactionStateIsKept[1]  Expecting code to raise a throwable
  serverErrorIsPropagatedAndTransactionStateIsKept[2]  Expecting code to raise a throwable
  transportErrorIsPropagatedAndTransactionStateIsKept[1]  Expected size: 2 but was: 1
  transportErrorIsPropagatedAndTransactionStateIsKept[2]  Expecting code to raise a throwable

Live failing before the fix (old driver installed, Toxiproxy run):

NetworkToxicityIT.testFailedRollbackThrowsAndKeepsTransactionForRetry:150
Expecting code to raise a throwable.
Tests run: 15, Failures: 1, Errors: 0, Skipped: 0

Passing after the fix:

$ ./mvnw -pl libsql-jdbc -am test
libSQL Hrana Codec ... SUCCESS (4 tests)
libSQL JDBC Driver ... SUCCESS (7 tests)
BUILD SUCCESS

$ DOCKER_CONFIG=/tmp/docker-config ./mvnw -pl libsql-itests -am verify
NetworkToxicityIT ... SUCCESS (5 tests)
libSQL Integration Tests ... SUCCESS (15 tests)
BUILD SUCCESS

$ ./mvnw spotless:apply
BUILD SUCCESS

DOCKER_CONFIG=/tmp/docker-config uses an empty public-image auth file because the sandbox blocks ~/.docker/config.json (AGENTS.md section 4). It does not change test behavior.

Out-of-scope defects

None newly found. The re-BEGIN-after-commit/rollback lifecycle gap is already tracked by #40.