Prepare Base

Announcement

At the start of execution, always post a visible message to the user:

"Loaded skill: prepare-base. Preparing base branch..."

Inputs

• base_branch: prefer to infer from context if specified by the user.

• If not provided, ask:

  "Which base branch would you like to prepare? (e.g. master)"

Do not proceed until base_branch is confirmed.

Procedure

0) Gather inputs

• If base_branch is not provided, request it.
• Stop execution until confirmed.

1) Verify working tree (safety gate)

• Run:

  git status --porcelain
  

• If output is not empty:

  • Display the modified/untracked files.

  • Ask:

    "You have uncommitted changes. Continue anyway? (yes/no)"

  • Accept only: yes, y, or confirm

  • If anything else → stop execution.

• Never stash, commit, or discard automatically.

2) Update remote references

• Run:

  git fetch --prune origin
  

• Notify user of result.

3) Checkout base branch (worktree-aware)

• Attempt:

  git checkout {base_branch}
  

• If it succeeds:

  • Notify: "Checked out branch: {base_branch}"
  • Proceed to step 4.

• If it fails because the branch is already checked out in another worktree (git reports something like '{base_branch}' is already used by worktree at '<path>'):

  • Do not retry, force, or attempt to detach/move the other worktree.
  • Stay on the current branch.
  • Notify: "{base_branch} is already checked out in another worktree (<path>); skipping local checkout. origin/{base_branch} (fetched in step 2) is the branch reference point for downstream steps."
  • Skip step 4 — the remote ref is already current from the fetch in step 2.
  • Proceed to step 5.

• Any other checkout failure → stop and report it to the user.

4) Pull latest

• Only runs if step 3 checked out base_branch locally.

• Pull latest changes:

  git pull origin {base_branch}
  

• Report:

  • already up to date, or
  • number of commits updated (if available)

5) Identify safe deletion candidates

Define:

• Local-only branch: branch with no upstream tracking reference
• Merged branch: fully merged into base_branch

Steps:

• List all local branches

• Exclude protected branches:

  • {base_branch}
  • master
  • main
  • develop
  • release/*
  • milestone/*

• Exclude branches checked out in any other worktree:

  git worktree list --porcelain
  

  Parse each worktree/branch pair. Any branch attached to a worktree path other than the current one is never a deletion candidate — it belongs to another worktree's in-progress work, regardless of merge or upstream status.

• Determine:

  • branches with no upstream
  • intersect with branches fully merged into base_branch

Command basis:

git branch --merged {base_branch}
git branch -vv

• Final candidate list = local-only ∩ merged ∩ not protected ∩ not checked out in another worktree

Note: --merged detects branches whose commits are direct ancestors of base_branch. Branches integrated via squash-merge (per project standards, all feature/bug branches are squash-merged) will typically NOT appear as merged, even though their work has landed. This step will under-report candidates for squash-merged branches — this is expected and safe, since step 8 uses -d, which would refuse to delete them anyway.

6) Handle no-op case

• If no candidates:

  "No safe local-only feature branches found to delete."

  • Stop execution

7) Confirmation gate

• Display candidate branches

• Ask:

  "The following branches will be deleted: {list}. Confirm? (yes/no)"

Accept only:

• yes
• y
• confirm

Anything else:

• Treat as rejection

• Output:

  "Branch deletion cancelled."

• Stop execution

8) Delete branches

For each confirmed branch:

git branch -d <branch>

• If deletion succeeds:
  • Notify: "Deleted branch: {branch}"
• If deletion fails (branch not detected as merged — e.g. squash-merged):
  • Notify: "{branch} could not be deleted with -d (not detected as merged — possibly squash-merged). Skipping."
  • Do NOT retry with -D
  • Continue to next candidate

(Do NOT use -D)

9) Summary

Provide final structured summary:

Summary

• Current branch: {base_branch}

• Remote references pruned: yes

• Latest changes pulled: yes

• Branches deleted:

  • branch-a
  • branch-b

• Branches skipped (not safely deletable):

  • branch-c

If none deleted:

• explicitly state: "No branches were deleted"

If none skipped:

• explicitly state: "No branches were skipped"

Guardrails

• Never delete master, main, or base_branch

• Never delete protected branches, including:

  • release/*
  • milestone/*

• Never delete without explicit confirmation

• Never push deletions to remote unless explicitly requested

• Never modify working tree automatically