Add custom git commands to dotfiles repo

Include git-branch-backup, git-fix-author, git-name-stash,
git-name-stash-apply, git-rebase-on, and git-rename-branch in a new
bin/ directory. Update install.sh to symlink them into ~/bin and
document them in the README.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -146,6 +146,19 @@ pyenv global 3.13.3
 tfenv install latest
 ```
 
+## Custom git commands
+
+The `bin/` directory contains custom git subcommands that are symlinked into `~/bin` by the install script. Make sure `~/bin` is on your PATH (the dotfiles handle this).
+
+| Command | Description |
+|---------|-------------|
+| `git branch-backup` | Create a timestamped backup branch of the current branch |
+| `git fix-author` | Rewrite commit author/email on historical commits |
+| `git name-stash <name>` | Stash changes with a named message |
+| `git name-stash-apply <name>` | Apply a stash by name |
+| `git rebase-on <branch>` | Back up current branch, then pull and rebase onto the given branch |
+| `git rename-branch <old> <new>` | Rename a branch locally and on the remote |
+
 ## What's included
 
 | File | Purpose |
@@ -159,5 +172,6 @@ tfenv install latest
 | `gitconfig` | Git aliases, colors, push config |
 | `gitignore_global` | Global gitignore (.DS_Store, *~) |
 | `fzf.zsh` | fzf PATH and shell integration |
+| `bin/git-*` | Custom git subcommands (see above) |
 | `Brewfile` | All Homebrew packages and casks |
 | `install.sh` | Symlink installer script |

bin/git-branch-backup

@@ -0,0 +1,9 @@
+#!/bin/zsh -f
+
+CURRENT_BRANCH=$(git rev-parse --abbrev-ref HEAD)
+if [[ $CURRENT_BRANCH == HEAD ]] ; then
+    CURRENT_BRANCH=$(git rev-parse --short HEAD) # in case detached HEAD
+fi
+NEW_BRANCH=${CURRENT_BRANCH}-backup-$(date +%Y%m%d-%H%M%S)
+git checkout -b $NEW_BRANCH
+git checkout -

bin/git-fix-author

@@ -0,0 +1,51 @@
+#!/bin/bash
+
+OLD=""
+NEW_NAME=""
+NEW_EMAIL=""
+
+ARGS=$(getopt -o o:n:h -l "old:,new:,help" -n $0 -- "$@")
+
+[ $? -eq 0 ] || exit 1
+
+eval set -- "$ARGS"
+
+while true
+do
+    case "$1" in
+        -o|--old)
+            OLD=$2
+            shift 2
+            ;;
+        -n|--new)
+            NEW=$2
+            NEW_NAME=$(echo "$NEW" | awk -F'[<>]' '{print $1}' | sed 's/ *$//')
+            NEW_EMAIL=$(echo "$NEW" | awk -F'[<>]' '{print $2}')
+            shift 2
+            ;;
+        -h|--help)
+            echo "usage: git fix-author --old diz@cpan.org --new 'Mike Eldridge <mike.eldridge@iinteractive.com>' ref"
+            exit
+            ;;
+        --)
+            shift
+            break
+            ;;
+    esac
+done
+
+echo "OLD=\"$OLD\""
+echo "NEW_NAME=\"$NEW_NAME\""
+echo "NEW_EMAIL=\"$NEW_EMAIL\""
+
+git filter-branch --commit-filter "
+    if [ \"\$GIT_COMMITTER_EMAIL\" = \"$OLD\" ];
+    then
+        GIT_COMMITTER_NAME=\"$NEW_NAME\";
+        GIT_AUTHOR_NAME=\"$NEW_NAME\";
+        GIT_COMMITTER_EMAIL=\"$NEW_EMAIL\";
+        GIT_AUTHOR_EMAIL=\"$NEW_EMAIL\";
+        git commit-tree \"\$@\";
+    else
+        git commit-tree \"\$@\";
+    fi" $@

bin/git-name-stash

@@ -0,0 +1,3 @@
+#!/bin/zsh -f
+
+git stash push -m $1

bin/git-name-stash-apply

@@ -0,0 +1,3 @@
+#!/bin/zsh -f
+
+git stash apply stash^{/$1}

bin/git-rebase-on

@@ -0,0 +1,4 @@
+#!/bin/zsh -f
+
+git branch-backup
+git checkout $1 && git pull && git checkout - && git rebase $1

bin/git-rename-branch

@@ -0,0 +1,4 @@
+#!/bin/zsh -f
+
+git branch-backup
+git checkout $1 && git branch -m $2 && git push origin -u $2 && git push origin --delete $1

install.sh

@@ -55,6 +55,15 @@ link_file "gitconfig"         ".gitconfig"
 link_file "gitignore_global"  ".gitignore_global"
 link_file "fzf.zsh"           ".fzf.zsh"
 
+# Symlink custom git commands into ~/bin
+echo ""
+echo "=== Custom git commands ==="
+mkdir -p "$HOME/bin"
+for cmd in "$DOTFILES_DIR"/bin/git-*; do
+    name="$(basename "$cmd")"
+    link_file "bin/$name" "bin/$name"
+done
+
 echo ""
 echo "=== Symlinks complete ==="
 echo ""