[zhanglistar]

Summary

Linux API jobs can stall behind exhausted hosted capacity while the dedicated runner is idle. Route the entire trusted Linux API dependency chain to iv-yezentk8ao3z47ge5tmm using the custom ci-linux-builds label, and alternate Linux x86_64 wheel builds between the two pools.

• Linux wheels use the dedicated runner on even workflow run numbers. API change planning and native runtime preparation use it on every eligible run, independent of run number. Linux API/CLI, MySQL/Redis and cuVS tests inherit their same-run native producer's destination, so no trusted Linux API dependency waits for hosted capacity.
• Only same-repository PRs and official branch pushes are eligible. Fork PRs, release/tag events, schedules and manual builds remain hosted. ARM, macOS, Windows, Studio, musl CLI and other test jobs keep their existing assignments.
• Require CI_LINUX_BUILDS_ENABLED=true before routing these jobs to the dedicated runner. CI_DISABLE_SELF_HOSTED=true returns new workflow runs to hosted capacity; already queued jobs retain their labels.
• Preserve Ubuntu 20.04/glibc 2.31 wheels and use Ubuntu 24.04 containers for API native preparation on both destinations. Self-hosted API consumers use disposable Ubuntu 24.04 containers, job-local HOME/Cargo/Rustup directories and ownership cleanup. Hosted consumers retain host execution. Database tests use service DNS in containers and loopback on hosts, with fresh MySQL 8.4 and Redis 6.2 services.
• Download Ubuntu packages over verified HTTPS, bootstrapping minimal containers with the host's read-only CA bundle. CI_UBUNTU_MIRROR overrides package sources only on self-hosted builds/tests.
• Add an explicit, five-minute readiness check to _build.yml that tests Docker, host/container connectivity and actual package installation without checking out repository code.
• Stabilize the remote task cancellation contract by observing delivery separately from durable cleanup, with bounded waits. Keep cancellation, empty active-handle index and terminal task-state assertions; slow MySQL cleanup must not be mistaken for a cancellation failure.

Validation

• 90 local runner-routing, packaging, release-selection and database CI contract tests passed, including inherited consumer routing, fork isolation, non-Linux assignments, container bootstrap/cleanup and service networking.
• actionlint, Ruff and whitespace checks passed.
• Dedicated runner package readiness: diagnostic run passed on iv-yezentk8ao3z47ge5tmm. Official Ubuntu endpoints timed out from both host and container; the configured HTTPS Aliyun mirror was reachable from both. Ubuntu 20.04 and 24.04 containers successfully downloaded indexes and installed Git and CA certificates. CI_UBUNTU_MIRROR=https://mirrors.aliyun.com/ubuntu and CI_LINUX_BUILDS_ENABLED=true are enabled.
• Before the consumer routing extension, Linux x64 wheels and API native preparation both passed on the dedicated runner in PR checks and API tests.
• Final implementation routing: even-numbered API run 11720 requested self-hosted / Linux / X64 / ci-linux-builds, and its prepare job started on iv-yezentk8ao3z47ge5tmm.
• API/CLI, cuVS and all five wheel platforms passed at fb2956b25. Its only failure was a one-second timeout in remote task cancellation cleanup; an isolated real-MySQL rerun passed with 107 passing cases and two expected skips.
• Cancellation test correction: 33 local Task/Work and concurrency cases passed (14 backend cases skipped locally). Injecting 1.2 seconds of durable-cleanup latency failed both original cancellation branches and passed both corrected branches. Ruff formatting/lint and whitespace checks passed.
• New head 66f9433da: API CI and PR CI are running.

Local checks verify routing and compatibility contracts; they do not establish a build speedup.