Scenario: Sapling sync metadata after a Git squash

Both monorepos imported a library, then tried its next release on a release branch. The release adds src/compat.txt. One uses Sapling's commit metadata; the other uses .splice.

A Git squash keeps the files but drops Sapling's metadata. A later release removes the file. With the old sync record as its base, Sapling interprets the file as a local addition and keeps it. .splice keeps the newer base, so git-splice can apply the deletion.

Output

setup.bash builds both monorepos before the squash:

$ build_scenario scenario_sapling_metadata

$ sl --version 2>/dev/null | head -1
Sapling 0.2.20260929-102736+288e0c2d

Sapling's release commit has the new sync record:

$ sl subtree inspect
{
  "xmerges": [
    {
      "version": 1,
      "url": "https://git.example.com/lib.git",
      "from_commit": "3bc7f68f0194869b6187f08d32f67bc1b585da06",
      "from_path": "",
      "to_path": "vendor/lib"
    }
  ]
}

Squash it with Git:

$ git switch -q main &&
>   git merge -q --squash release &&
>   git commit -q -m "squash release"
Squash commit -- not updating HEAD

$ sl subtree inspect
no subtree metadata found for commit 745eec9ff36d

The commands now run in the monorepo using git-splice:

$ cd ../splice-monorepo

The same squash keeps the .splice file's new sync point:

$ git switch -q main &&
>   git merge -q --squash release &&
>   git commit -q -m "squash release"
Squash commit -- not updating HEAD

$ git config --file vendor/lib/.splice splice.commit
3bc7f68f0194869b6187f08d32f67bc1b585da06

The library removes compat.txt in the next release:

$ git clone -q "$UPSTREAM" ../lib-dev &&
>   git -C ../lib-dev rm -q src/compat.txt &&
>   git -C ../lib-dev commit -q -m "release drops compat" &&
>   git -C ../lib-dev push -q

The commands now run in the monorepo using Sapling:

$ cd ../monorepo

Sapling finds the record before the squashed release and keeps the file:

$ sl subtree merge --url https://git.example.com/lib.git \
>   -r "$(git --git-dir="$UPSTREAM" rev-parse main)" --to-path vendor/lib
using cached git repo at $VCS_ROOT/sapling-cache/gitrepos/316067af85b8bd24e96f811d9f55a8f2d20eed8dcae7796fe42d9eb9ea621a17
pulling '18fd6f7bfdc2047f0641984b501e3373d55c895f' from 'https://git.example.com/lib.git'
searching for merge base ...
found the last subtree import commit 0318bf4fb04d
merge base: 24e77474eea7
update complete
(subtree merge, don't forget to commit)

$ ls vendor/lib/src
compat.txt
parse.txt

The commands now run in the monorepo using git-splice:

$ cd ../splice-monorepo

The newer sync point lets the pull remove the file:

$ git splice pull vendor/lib
ok   vendor/lib fetched (main moved 3bc7f68..18fd6f7)
ok   vendor/lib: pulled 18fd6f7

$ ls vendor/lib/src
parse.txt

Output​

Output