[backport] Backport sweep for 9.0

[valkeyrie-ops]

Backport sweep for 9.0

Automated cherry-picks from PRs marked "To be backported".

Applied

Source PR	Title	Detail
#4104	Avoid offloading writes to IO threads for the slot migration export job while snapshotting.	conflicts resolved by Claude Code
#4229	Validate slot import ranges when loading from RDB
#4210	Check and reject invalid slot import job names

AI resolution details are posted as comments on this PR when available.

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Generated by valkey-ci-agent using Claude Code.

[valkeyrie-ops]

AI conflict resolution: source PR #4104

Avoid offloading writes to IO threads for the slot migration export job while snapshotting.

2 conflicted files

Claude Summary

All conflicts are resolved. Here's a summary of what I did:

Source PR intent: Prevent IO-thread write offloading for slot migration export clients while snapshotting (to avoid query buffer desync during pipelining), plus a defensive early-return in killSlotMigrationChild and IO-state checks before snapshotting.

Resolutions:

1. src/io_threads.c — The conflict was in the include block at the top of the file. Upstream's unstable branch has #include "queues.h" and #include <sys/resource.h> as pre-existing context, but neither exists on the 9.0 branch (I confirmed src/queues.h is absent). The PR itself only added #include "cluster_migrateslots.h", so I kept just that one include. The functional change — the guard if (c->slot_migration_job && !clusterSlotMigrationShouldInstallWriteHandler(c)) return C_ERR; in trySendWriteToIOThreads — auto-merged cleanly, and I verified both the slot_migration_job client field (server.h:1298) and clusterSlotMigrationShouldInstallWriteHandler (cluster_migrateslots.h:20) exist on 9.0.

2. tests/unit/cluster/cluster-migrateslots.tcl — The conflict was at the end of the file, where the cherry-pick tried to append two start_cluster test blocks (remaining_repl_size and slot-migration-max-failover-repl-bytes -1) that exist on unstable but not on 9.0. The PR only modified their tag lines (adding network); it didn't introduce those tests. I dropped them rather than importing tests outside the PR's scope. The network tag additions to the 5 start_cluster blocks that do exist on 9.0 were auto-merged and are intact.

3. src/cluster_migrateslots.c (auto-merged, staged) — Verified it matches the upstream diff: the exit-pipe early-return in killSlotMigrationChild and the io_write_state/io_read_state idle checks before snapshotting in proceedWithSlotMigration. server.slot_migration_child_exit_pipe, CLIENT_IDLE, and both IO-state fields all exist on 9.0. No adaptation was needed
   ... summary truncated.

AI-resolved conflicted files

• src/io_threads.c — view diff
• tests/unit/cluster/cluster-migrateslots.tcl — view diff

Full backport commit diff: commit efe4f502181a.

Please review these AI resolutions for correctness before merging.