Scenario: tracked-branch

The monorepo is on feature. Each splice should sync with another upstream branch than feature: vendor/a/ with development, where its upstream's team works, vendor/b/ with review.

Monorepo: a clones vendor/a/ at k, b clones vendor/b/ at m, both on main, then the branch feature, with no changes.
Upstream of vendor/a/: k on main, and l on development.
Upstream of vendor/b/: m on main, and n on review.

tracked(X) is the upstream branch a splice tracks on the monorepo branch X, if any: here tracked(feature) is development for vendor/a/ and review for vendor/b/. T is the fetched tracked branch where there is one, else the branch named like X.

--branch names another upstream branch for one command; --track also keeps it, as git push -u does: on this monorepo branch, every command syncs the splice with it from then on. git splice fetch --track sets it without a pull or a push, so status can show the result before anything changes.

Output

setup.bash builds this state:

$ build_scenario scenario_tracked_branch

Neither upstream has a feature branch, so both splices compare with main, as a PR would:

$ git splice status
On branch feature

  unchanged, no upstream branch  vendor/a
  unchanged, no upstream branch  vendor/b

Track development for vendor/a/:

$ git splice fetch --branch development --track vendor/a
ok   vendor/a fetched
ok   vendor/a: 'feature' tracks 'development' from now on

$ git splice status
On branch feature

  behind 1                       vendor/a -> development  tracked on feature, local

  unchanged, no upstream branch  vendor/b

vendor/a/ now compares with development, which has a commit to pull. The hint says it's tracked on feature, and only in this clone. Track review for vendor/b/:

$ git splice fetch --branch review --track vendor/b
ok   vendor/b fetched
ok   vendor/b: 'feature' tracks 'review' from now on

The monorepo's a and b, which is H, feature and main; in vendor/a/, k, which is U(H), R and main, and l on top, which is T, tracked(feature) and development; in vendor/b/ the same with m, and n on top, which is review

Each upstream has its own tracked branch, by its key, in the monorepo's branch.feature.splice, as drawn above:

$ git config --get-all branch.feature.splice
a:development
b:review

$ git splice status
On branch feature

  behind 1  vendor/a -> development  tracked on feature, local
  behind 1  vendor/b -> review       tracked on feature, local

From here, git splice pull vendor/a pulls development, and push goes there too. To undo it, --no-track stops tracking, and the splice compares with main again:

$ git splice fetch --no-track vendor/b
ok   vendor/b fetched
ok   vendor/b: 'feature' no longer tracks 'review'

$ git splice status
On branch feature

  behind 1                       vendor/a -> development  tracked on feature, local

  unchanged, no upstream branch  vendor/b

push, pull and merge take --branch <name> --track too, and track the branch once they succeed.
A tracked branch is a name in the monorepo's config, no ref, unlike Git's remote-tracking branches. It belongs to the monorepo branch: git branch -m takes it along, git branch -d removes it, and git splice key renames the key in it.

Output​

Output