setupHarperWithFixture overwrites ctx.harper, dropping pre-set hostname (breaks multi-node add_node)

[kriszyp]

Summary

setupHarperWithFixture overwrites ctx.harper before calling startHarper, discarding caller-set fields such as hostname. In a multi-node test this makes the replication config's securePort reference a different address than the one Harper actually binds to, producing ECONNREFUSED on add_node.

Context / repro

• Found while building a 2-node cluster cache test (Add cluster integration test: sourcedFrom replicationSource: true (§5.5 Cat 15) harper-pro#415). Setting ctx.harper.hostname before setupHarperWithFixture had no effect because the function replaces ctx.harper wholesale.
• Workaround: call startHarper directly with a manually-prepared dataRootDir + hostname set on ctx.harper, bypassing setupHarperWithFixture.

Expected

• setupHarperWithFixture should merge into / preserve caller-set fields on ctx.harper (especially hostname) rather than overwriting them, so the fixture helper is usable in multi-node / replication tests.

References

• Workaround: Add cluster integration test: sourcedFrom replicationSource: true (§5.5 Cat 15) harper-pro#415 (integrationTests/cluster/cacheReplicationSource.test.mjs)

_{Filed by Claude (Opus 4.8) on behalf of Kris while implementing the release-testing coverage gaps.}