Merge remote branch state: keep the selector-with-ubuntu-latest-default verdict resolution
Two sessions resolved the same all-checks-passed conflict differently. The remote's version is the one kept: the selector with '|| ubuntu-latest' covers a standard-hosted outage too, which a bare ubuntu-latest pin does not, and its runbook wording is internally consistent at four failover jobs. Reverted this side's three-job doc downgrade.
This commit is contained in:
Chinesezjc
@@ -2,5 +2,5 @@
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# side as of the last confirmed-consistent state. Both languages carry equal authority;
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# after editing either side, bring the other along and re-record with:
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# pnpm run verify-translation-pairing --write .agents/notes/implemented/process/2026-07-26-ci-failover-runbook.md
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2026-07-26-ci-failover-runbook.md: f2a3b46dc10adc3d13ebce8506a04c38fad07c05
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2026-07-26-ci-failover-runbook.zh.md: 8fc17749b8999f50f2efb65814b6cb478603da58
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2026-07-26-ci-failover-runbook.md: 80dd7c4291e3de11c2f13b3247af56762396c720
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2026-07-26-ci-failover-runbook.zh.md: 7933a857f1559c540fccc2cd89352c4fe351dd7e
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@@ -6,11 +6,11 @@ English | [中文](2026-07-26-ci-failover-runbook.zh.md)
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## Problem
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The three required Linux worker jobs in [CI](../../../../.github/workflows/ci.yml) (`node 24 / static`, `node 24 / coverage`, `node 24 / snapshots and artifacts`) run on the hosted enterprise 32-core pools. When those pools degrade — jobs queue indefinitely, the enterprise labels vanish, or GitHub-side capacity fails — every open pull request becomes unmergeable, and the ordinary recovery of merging a fix is itself deadlocked behind the very required checks that cannot run. An outage therefore needs a switch any responder with repository write access can throw without merging anything.
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The three required Linux worker jobs in [CI](../../../../.github/workflows/ci.yml) (`node 24 / static`, `node 24 / coverage`, `node 24 / snapshots and artifacts`) and the required verdict job that aggregates them (`all checks passed`) run on the hosted enterprise 32-core pools. When those pools degrade — jobs queue indefinitely, the enterprise labels vanish, or GitHub-side capacity fails — every open pull request becomes unmergeable, and the ordinary recovery of merging a fix is itself deadlocked behind the very required checks that cannot run. An outage therefore needs a switch any responder with repository write access can throw without merging anything.
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## Decision
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Each of the three required Linux worker jobs resolves its runner pool through the `DSH_CI_FAILOVER` repository variable. Unset (normal), they run on the hosted enterprise pools. Set to `selfhosted` by any repository writer, all three retarget onto the in-house self-hosted `vm-backup` pool, coverage and snapshot concurrency drop to shared-VM bounds, and the hosted-path pnpm cache restores are skipped. The `all checks passed` verdict job stays on standard hosted `ubuntu-latest` in both states: it only reads `needs.*.result`, so keeping it off both custom pools is what stops the branch-protection verdict from queueing on whichever pool failed. The switch is writer-manageable repository state, not a merge, so it works while every check is red. The in-house pool's readiness is continuously re-proven by the `serial / linux (self-hosted standby)` lane, which runs the complete unsharded aggregate on every master push.
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Each of the three required Linux worker jobs — and the `all checks passed` verdict job, which would otherwise stay queued on the failed pool even after every worker passed — resolves its runner pool through the `DSH_CI_FAILOVER` repository variable. Unset (normal), they run on the hosted enterprise pools. Set to `selfhosted` by any repository writer, all four retarget onto the in-house self-hosted `vm-backup` pool, coverage and snapshot concurrency drop to shared-VM bounds, and the hosted-path pnpm cache restores are skipped. The switch is writer-manageable repository state, not a merge, so it works while every check is red. The in-house pool's readiness is continuously re-proven by the `serial / linux (self-hosted standby)` lane, which runs the complete unsharded aggregate on every master push.
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### What the in-house pool is
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@@ -22,7 +22,7 @@ Each of the three required Linux worker jobs resolves its runner pool through th
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2. Retrigger the required jobs so they re-resolve their pool. Jobs already **queued** for the hosted labels do not retarget and cannot be re-run in place, so for the documented indefinite-queue outage, cancel the stuck run and re-run all jobs, or push a new commit; "Re-run failed jobs" only helps once a job has actually failed rather than queued.
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3. That is the entire switch. Under failover the workflow also, automatically: drops `DSH_COVERAGE_MAX_WORKERS` to 8 and `DSH_SNAPSHOT_MAX_CONCURRENCY` to 12 (sized for six always-on instances: worst case 6 × 8 = 48 coverage workers on the 64-core VM) (shared-VM contention bounds), and skips the hosted-path pnpm cache restores (the VM's persistent store serves warm installs).
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#**Dependabot exception.** All three selectors deliberately exclude `dependabot[bot]`: under failover, Dependabot PRs stay queued for the hosted pool rather than executing dependency-supplied code on the persistent VM. A Dependabot PR that remains queued during an outage is expected behavior, not a failed switch; it completes when the hosted pool recovers.
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#**Dependabot exception.** All four selectors deliberately exclude `dependabot[bot]`: under failover, Dependabot PRs stay queued for the hosted pool rather than executing dependency-supplied code on the persistent VM. A Dependabot PR that remains queued during an outage is expected behavior, not a failed switch; it completes when the hosted pool recovers.
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**Who can flip the variable.** GitHub's API lets any collaborator with write access manage repository variables, so the switch is writer-level, not strictly admin-only. In this repository's trust model that is not an escalation: the runner group admits all workflows of this private, fork-disabled repository (a deliberate trade to make PR-ref failover possible at all), so any writer could already reach the VM by pushing a branch workflow. The boundary against untrusted code is repository membership; the variable only routes work for members.
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@@ -37,7 +37,7 @@ Delete the `DSH_CI_FAILOVER` variable (or set it to anything other than `selfhos
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### Trust boundary
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The variable is writer-manageable repository state; a pull request event itself can neither set it nor read a different value into effect, and the selector expressions live in workflow definitions. Note that under failover, `pull_request` runs execute the PR merge ref's own workflow definition — the boundary against untrusted code is repository membership (private, forking disabled, Dependabot excluded by the selectors), not the variable. Note on runner-group policy: pinning the runner group to the master-ref workflow is **incompatible** with this failover — the three failover jobs are `pull_request` runs evaluated from PR merge refs, and a master-pinned group leaves them queued (observed live on 2026-07-27; the group was widened to all workflows of this repository to unblock the switch). A stricter runner-side policy therefore costs PR failover; the shipped posture accepts repository-scoped, all-workflow group access.
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The variable is writer-manageable repository state; a pull request event itself can neither set it nor read a different value into effect, and the selector expressions live in workflow definitions. Note that under failover, `pull_request` runs execute the PR merge ref's own workflow definition — the boundary against untrusted code is repository membership (private, forking disabled, Dependabot excluded by the selectors), not the variable. Note on runner-group policy: pinning the runner group to the master-ref workflow is **incompatible** with this failover — the four failover jobs are `pull_request` runs evaluated from PR merge refs, and a master-pinned group leaves them queued (observed live on 2026-07-27; the group was widened to all workflows of this repository to unblock the switch). A stricter runner-side policy therefore costs PR failover; the shipped posture accepts repository-scoped, all-workflow group access.
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## Alternatives considered
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@@ -6,11 +6,11 @@ Status: implemented
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## 问题
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[CI](../../../../.github/workflows/ci.yml) 中三个必需的 Linux 工作作业（`node 24 / static`、`node 24 / coverage`、`node 24 / snapshots and artifacts`）运行在托管的企业级 32 核池上。当这些托管池发生故障——作业无限排队、企业标签消失或 GitHub 侧容量故障——所有开启的拉取请求都无法合并，而"合并一个修复"这一常规恢复手段本身正被那些无法运行的必需检查死锁。因此故障需要一个任何具备仓库写权限的响应者都能在不合并任何代码的情况下触发的开关。
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[CI](../../../../.github/workflows/ci.yml) 中三个必需的 Linux 工作作业（`node 24 / static`、`node 24 / coverage`、`node 24 / snapshots and artifacts`）以及聚合它们的必需判定作业（`all checks passed`）运行在托管的企业级 32 核池上。当这些托管池发生故障——作业无限排队、企业标签消失或 GitHub 侧容量故障——所有开启的拉取请求都无法合并，而"合并一个修复"这一常规恢复手段本身正被那些无法运行的必需检查死锁。因此故障需要一个任何具备仓库写权限的响应者都能在不合并任何代码的情况下触发的开关。
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## 决策
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三个必需的 Linux 工作作业各自通过仓库变量 `DSH_CI_FAILOVER` 解析运行器池。变量不存在（正常）时它们运行在托管企业池上；由任何具备写权限的协作者设为 `selfhosted` 时，三者全部切换到公司自有的自托管 `vm-backup` 池，coverage 与 snapshot 的并发降到共享虚拟机上限，并跳过托管路径的 pnpm 缓存恢复。`all checks passed` 判定作业在两种状态下都留在标准托管的 `ubuntu-latest` 上：它只读取 `needs.*.result`，因此让它远离两个自定义池，正是分支保护判定不会滞留在出故障的那个池队列中的原因。这个开关是写者可管理的仓库状态而非一次合并，因此在所有检查都是红色时仍然有效。自有池的就绪状态由 `serial / linux (self-hosted standby)` 通道持续验证——每次 master 推送都在其上运行完整的未分片聚合流程。
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三个必需的 Linux 工作作业——以及 `all checks passed` 判定作业（若不随切换，即使全部工作作业通过，它仍会滞留在故障池的队列中）——各自通过仓库变量 `DSH_CI_FAILOVER` 解析运行器池。变量不存在（正常）时它们运行在托管企业池上；由任何具备写权限的协作者设为 `selfhosted` 时，四者全部切换到公司自有的自托管 `vm-backup` 池，coverage 与 snapshot 的并发降到共享虚拟机上限，并跳过托管路径的 pnpm 缓存恢复。这个开关是写者可管理的仓库状态而非一次合并，因此在所有检查都是红色时仍然有效。自有池的就绪状态由 `serial / linux (self-hosted standby)` 通道持续验证——每次 master 推送都在其上运行完整的未分片聚合流程。
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### 自有池是什么
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@@ -22,7 +22,7 @@ Status: implemented
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2. 重新触发必需作业，使其重新解析运行器池。已经为托管标签**排队**的作业不会重定向，也无法原地 re-run，因此对于本手册所述的无限排队故障，应取消卡住的运行并 re-run all jobs，或推送一个新提交；“Re-run failed jobs”只有在作业真正失败（而非仍在排队）时才有用。
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3. 切换到此完成。故障切换状态下工作流还会自动：把 `DSH_COVERAGE_MAX_WORKERS` 降为 8、`DSH_SNAPSHOT_MAX_CONCURRENCY` 降为 12（按 6 个常驻实例定容：最坏 6 × 8 = 48 个覆盖率工作进程对 64 核）（共享虚拟机的争抢上限），并跳过托管路径的 pnpm 缓存恢复（虚拟机的持久 store 直接提供热安装）。
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#**Dependabot 例外。**三个选择器都刻意排除了 `dependabot[bot]`：故障切换期间，Dependabot 拉取请求继续在托管池排队，而不是把依赖方提供的代码放到持久化虚拟机上执行。故障期间 Dependabot PR 持续排队是预期行为而非切换失败；托管池恢复后它会自行完成。
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#**Dependabot 例外。**四个选择器都刻意排除了 `dependabot[bot]`：故障切换期间，Dependabot 拉取请求继续在托管池排队，而不是把依赖方提供的代码放到持久化虚拟机上执行。故障期间 Dependabot PR 持续排队是预期行为而非切换失败；托管池恢复后它会自行完成。
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**谁能扳动这个变量。**GitHub 的 API 允许任何具有写权限的协作者管理仓库变量，因此该开关实际是写者级而非严格的管理员级。在本仓库的信任模型下这并不构成越权：runner group 接纳本私有、禁 fork 仓库的全部工作流（这是让 PR 引用的故障切换得以成立的刻意取舍），因此任何写者本就可以通过推送分支工作流触达这台虚拟机。抵御不可信代码的边界是仓库成员资格；变量只是为成员路由工作。
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@@ -37,7 +37,7 @@ Status: implemented
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### 信任边界
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该变量是写者可管理的仓库状态；`pull_request` 事件本身既不能设置它，也不能让不同的值生效，选择器表达式存在于工作流定义中。需要注意：故障切换期间，`pull_request` 运行执行的是 PR merge 引用自带的工作流定义——抵御不可信代码的边界是仓库成员资格（私有、禁 fork、选择器排除 Dependabot），而非该变量。关于 runner group 策略的说明：把 runner group 绑定到 master 引用的工作流与本故障切换机制**不兼容**——三个故障切换作业是从 PR merge 引用求值的 `pull_request` 运行，master 绑定的组会让它们持续排队（2026-07-27 实际故障中亲历；当时将组放宽为本仓库全部工作流才疏通了切换）。更严格的运行器侧策略以牺牲 PR 故障切换为代价；当前采用的形态是仓库范围、全工作流的组访问。
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该变量是写者可管理的仓库状态；`pull_request` 事件本身既不能设置它，也不能让不同的值生效，选择器表达式存在于工作流定义中。需要注意：故障切换期间，`pull_request` 运行执行的是 PR merge 引用自带的工作流定义——抵御不可信代码的边界是仓库成员资格（私有、禁 fork、选择器排除 Dependabot），而非该变量。关于 runner group 策略的说明：把 runner group 绑定到 master 引用的工作流与本故障切换机制**不兼容**——四个故障切换作业是从 PR merge 引用求值的 `pull_request` 运行，master 绑定的组会让它们持续排队（2026-07-27 实际故障中亲历；当时将组放宽为本仓库全部工作流才疏通了切换）。更严格的运行器侧策略以牺牲 PR 故障切换为代价；当前采用的形态是仓库范围、全工作流的组访问。
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## 曾考虑的替代方案
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16
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vendored
16
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vendored
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# 'cancelled' and 'skipped'.
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all-checks-passed:
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name: all checks passed
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# This bookkeeping-only verdict must not depend on custom-pool provisioning.
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# Standard hosted capacity is also what keeps it out of the failover path:
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# pinned to either custom pool, an outage of that pool would leave the
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# branch-protection verdict queued forever even after every worker job
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# passed on the other pool.
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runs-on: ubuntu-latest
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# This bookkeeping-only verdict must not depend on custom-pool
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# provisioning (master's #734 moved it to ubuntu-latest) — and under
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# failover it follows the same selector as the worker jobs it
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# aggregates, so a standard-hosted outage cannot strand the
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# branch-protection verdict either (observed 2026-07-27).
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runs-on: >-
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${{ vars.DSH_CI_FAILOVER == 'selfhosted'
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&& github.event.pull_request.user.login != 'dependabot[bot]'
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&& fromJSON('["self-hosted", "linux", "x64", "vm-backup"]')
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|| 'ubuntu-latest' }}
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needs: [node-24, node-24-coverage, node-24-consumers, node-compat, python-sdk, windows]
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if: always() && github.event_name == 'pull_request'
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steps:
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Block a user