Development record
A build run's dependent lane cannot start until its predecessor has merged into the default branch: readiness reads a predecessor as landed only when its lane is done, its pull request an ancestor of the default branch, so a step that needs another waits a whole preflight and merge-queue cycle (about one to two and a half hours each on 2026-10-22) before it opens. Stacked changes are standard practice for dependent work (Graphite, Sapling and ghstack stacks, and merge queues taking a stack in order), and on 2026-10-22/23 that shape was rolled by hand twice: merge-gate steps 2 and 3, and model-matrix step 2 stacked on the route branch. Building it is more than a fix: the dependent lane's pull request is based on the predecessor's branch, the stack merges in order, and a lane rebases (and re-stamps what it resolved) when the predecessor changes.
A build run's dependent lane cannot start until its predecessor has merged into the default branch: readiness reads a predecessor as landed only when its lane is done, its pull request an ancestor of the default branch, so a step that needs another waits a whole preflight and merge-queue cycle (about one to two and a half hours each on 2026-10-22) before it opens. Stacked changes are standard practice for dependent work (Graphite, Sapling and ghstack stacks, and merge queues taking a stack in order), and on 2026-10-22/23 that shape was rolled by hand twice: merge-gate steps 2 and 3, and model-matrix step 2 stacked on the route branch. Building it is more than a fix: the dependent lane's pull request is based on the predecessor's branch, the stack merges in order, and a lane rebases (and re-stamps what it resolved) when the predecessor changes.
Frontmatter
| id | iss-2610230856272073 |
|---|---|
| type | issue |
| lifecycle | open |
| severity | minor |
.abcd/work/issues/open/iss-2610230856272073-a-dependent-build-lane-waits-for-its.md
open on GitHub ↗ · commit history ↗
References1
- itd-2610230856403803A build run's dependent lane cannot start until its predecessor has merged into the default branch: readiness reads a predecessor as landed only when its lane is done, its pull request an ancestor of the default branch, so a step that needs another waits a whole preflight and merge-queue cycle (about one to two and a half hours each on 2026-10-22) before it opens. Stacked changes are standard practice for dependent work (Graphite, Sapling and ghstack stacks, and merge queues taking a stack in order), and on 2026-10-22/23 that shape was rolled by hand twice: merge-gate steps 2 and 3, and model-matrix step 2 stacked on the route branch. Building it is more than a fix: the dependent lane's pull request is based on the predecessor's branch, the stack merges in order, and a lane rebases (and re-stamps what it resolved) when the predecessor changes.related