Cancelling a build only killed the running build process; the synchronous
preparation phases — most notably a multi-minute Docker image build, but also
the Gradle-volume preparation — ran to completion and kept the concurrency
slot occupied, so the next queued build stayed PENDING for a long time.
Build runners now report every auxiliary process through an onAuxProcess sink
(GitCommandRunner gained an onProcess hook), and the executor registers them
like the build process, so cancellation terminates whatever is currently
running. Measured on vm4006: cancel to next-build-running is ~3s in the
normal case; the unit test covers the aux-phase case.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Two fixes from the vm4006 rollout (docs/plan/16-git-in-docker-builds.md):
Rootless daemons map the host user to container root, so running the build
container as --user <host-uid> put it into the subuid range and it could not
even create .gradle in a fresh worktree (legacy only worked because its
ownership-repair chown had accidentally moved build/ and .gradle/ into subuid
ownership in its reused primary checkout). The container now always runs as
--user 0: the unprivileged host user under rootless, real root under rootful
where the ownership repair still applies; under rootless it degenerates to 0:0.
Git now works inside build containers: the primary .git is mounted read-only
with .git/gittally/ masked by an empty tmpfs (git.token and the control token
stay unreachable, the workspace bind resurfaces only the build's own worktree)
and the worktree admin dir mounted read-write for index-refreshing commands.
Verified on vm4006: git log/status succeed, the machine config is invisible,
ref writes fail on the read-only mount.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
