Absorb fixups

You're three branches deep in a stack and you spot a typo (or a missed null-check) in commit 4. You want the fix to land in commit 4, not as a fresh commit on the current tip.

What you'd otherwise do

The manual flow is a three-step template (substitute <sha-of-commit-4> for the actual ancestor SHA you want the fixup to land on):

git commit --fixup=<sha-of-commit-4>
git rebase -i --autosquash main
sm restack

Three commands, the middle one drops you into an interactive editor. Repeat per hunk if multiple commits are involved.

With sm absorb

sm absorb wraps git-absorb, which matches each hunk to the commit that introduced the surrounding code:

sm absorb

What happens:

1. git-absorb looks at every hunk in the working tree.
2. For each hunk, it git blames the surrounding lines to find the right ancestor commit.
3. It creates fixup! commits and runs git rebase --autosquash to fold them in.
4. sm restacks every descendant so they pick up the new commits.

End result: one command, no editor, descendants are consistent.

Prerequisites

Install git-absorb from one of the sources below.

On macOS via Homebrew:

brew install git-absorb

On any platform with rustup / cargo:

cargo install git-absorb

If git-absorb is missing, sm absorb prints an install hint and exits. It's not bundled with sm.

Worked example

Starting state:

stac-man

main
└─ feat/api-models
   └─ feat/api-handlers
      └─ feat/api-tests  ← current

(Working tree on feat/api-tests is dirty with a fix that conceptually belongs in feat/api-handlers.)

The dirty hunk lives in internal/handlers/login.go — code that was originally written in feat/api-handlers's second commit. Run:

sm absorb

Output:

✓ absorbed into ancestors of feat/api-tests (base: main)
  descendants restacked

Under the hood:

• The fixup landed on the right commit in feat/api-handlers.
• feat/api-tests was rebased onto the rewritten feat/api-handlers.
• Your working tree is clean.

Picking a base

If you want absorb to consider only a portion of the stack, pass --base:

sm absorb --base feat/api-handlers

Now git-absorb will not consider commits below feat/api-handlers as fixup targets.

When absorb can't help

git-absorb works on hunks, not whole files. If your fix touches code that was added across multiple commits, absorb may decline to find a single target — it will print which hunks were absorbed and which were left behind.

For those leftover hunks, the fallback is to commit them on the current tip with sm modify, or to use git commit --fixup=<sha> manually.

On conflict

If restacking descendants conflicts after the absorb, the standard pause protocol kicks in:

⚠ rebase paused on feat/api-tests

Resolve, git add, sm continue.

See also

• sm absorb — flag reference.
• sm modify — when the fix belongs on the current tip.
• git-absorb upstream — the underlying tool.