Add standalone Git identity tools

AGENTS.md

@@ -34,6 +34,7 @@
 ## Git & Development Workflow
 - **Branch naming**: Use simple descriptive names without prefixes
 - **Commits**: Commit signing enabled, write clear commit messages
+- **Agent commits**: Codex-authored commits should run `git-assume bk-codex` before committing; Amp-authored commits should run `git-assume bk-amp`. Use plain `git commit` without `-S`. These identities are intentionally unsigned so agents do not block on 1Password signing approval.
 - **Dependencies**: Keep `go.mod` clean, use `go mod tidy` regularly
 - **Security**: Never commit secrets, use environment variables or secure vaults
 - **CI/CD**: Ensure tests pass before merging, use automated linting

bin/git-assume

@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+
+set -e
+
+identity="$1"
+
+if [[ -z $identity ]]; then
+  echo "Usage: git-assume <identity>" >&2
+  exit 2
+fi
+
+if ! name=$(git config "identity.$identity.name"); then
+  echo "Missing name for $identity" >&2
+  exit 1
+fi
+
+if ! email=$(git config "identity.$identity.email"); then
+  echo "Missing email for $identity" >&2
+  exit 1
+fi
+
+config_scope=()
+if git_dir=$(git rev-parse --git-dir 2>/dev/null) \
+  && git_common_dir=$(git rev-parse --git-common-dir 2>/dev/null) \
+  && [[ $git_dir != "$git_common_dir" ]] \
+  && [[ "$(git config --bool --get extensions.worktreeConfig 2>/dev/null)" == "true" ]]; then
+  config_scope=(--worktree)
+fi
+
+git config "${config_scope[@]}" user.identity "$identity"
+git config "${config_scope[@]}" user.name "$name"
+git config "${config_scope[@]}" user.email "$email"
+
+if signingkey=$(git config "identity.$identity.signingkey"); then
+  git config "${config_scope[@]}" user.signingkey "$signingkey"
+  git config "${config_scope[@]}" commit.gpgsign true
+else
+  git config "${config_scope[@]}" --unset user.signingkey 2>/dev/null || true
+  git config "${config_scope[@]}" commit.gpgsign false
+fi

bin/git-github-auth

@@ -0,0 +1,110 @@
+#!/usr/bin/env bash
+
+set -e
+
+usage() {
+  echo "Usage: git-github-auth <gh|https|ssh> [remote]" >&2
+}
+
+mode="$1"
+remote="${2:-origin}"
+
+if [[ -z $mode ]]; then
+  usage
+  exit 2
+fi
+
+case "$mode" in
+  gh | https)
+    transport="https"
+    ;;
+  ssh)
+    transport="ssh"
+    ;;
+  *)
+    usage
+    exit 2
+    ;;
+esac
+
+if ! current_url=$(git config --get "remote.$remote.url" 2>/dev/null); then
+  current_url=$(git remote get-url "$remote" 2>/dev/null || true)
+fi
+
+if [[ -z $current_url ]]; then
+  echo "Missing remote: $remote" >&2
+  exit 1
+fi
+
+repo_path="${current_url%.git}"
+case "$repo_path" in
+  https://github.com/*)
+    repo_path="${repo_path#https://github.com/}"
+    ;;
+  http://github.com/*)
+    repo_path="${repo_path#http://github.com/}"
+    ;;
+  git@github.com:*)
+    repo_path="${repo_path#git@github.com:}"
+    ;;
+  ssh://git@github.com/*)
+    repo_path="${repo_path#ssh://git@github.com/}"
+    ;;
+  github.com/*)
+    repo_path="${repo_path#github.com/}"
+    ;;
+  *)
+    echo "Cannot infer GitHub owner/repo from remote URL: $current_url" >&2
+    exit 1
+    ;;
+esac
+
+IFS=/ read -r owner repo _ <<<"$repo_path"
+if [[ -z $owner || -z $repo ]]; then
+  echo "Cannot infer GitHub owner/repo from remote URL: $current_url" >&2
+  exit 1
+fi
+
+repo="${repo%.git}"
+
+case "$transport" in
+  https)
+    target_base="https://github.com/$owner/$repo"
+    source_bases=(
+      "git@github.com:$owner/$repo"
+      "ssh://git@github.com/$owner/$repo"
+      "github.com/$owner/$repo"
+      "http://github.com/$owner/$repo"
+    )
+    ;;
+  ssh)
+    target_base="git@github.com:$owner/$repo"
+    source_bases=(
+      "https://github.com/$owner/$repo"
+      "http://github.com/$owner/$repo"
+      "ssh://git@github.com/$owner/$repo"
+      "github.com/$owner/$repo"
+    )
+    ;;
+esac
+
+config_scope=()
+if git_dir=$(git rev-parse --git-dir 2>/dev/null) \
+  && git_common_dir=$(git rev-parse --git-common-dir 2>/dev/null) \
+  && [[ $git_dir != "$git_common_dir" ]]; then
+  if [[ "$(git config --bool --get extensions.worktreeConfig 2>/dev/null)" != "true" ]]; then
+    echo "Refusing to change shared config from a linked worktree without extensions.worktreeConfig=true" >&2
+    exit 1
+  fi
+  config_scope=(--worktree)
+fi
+
+git config "${config_scope[@]}" --remove-section "url.https://github.com/$owner/$repo" 2>/dev/null || true
+git config "${config_scope[@]}" --remove-section "url.git@github.com:$owner/$repo" 2>/dev/null || true
+
+for source_base in "${source_bases[@]}"; do
+  git config "${config_scope[@]}" --add "url.$target_base.insteadOf" "$source_base"
+done
+
+echo "$remote fetch: $(git remote get-url "$remote")"
+echo "$remote push:  $(git remote get-url --push "$remote")"

git/README.md

@@ -15,6 +15,8 @@ The Git configuration in these dotfiles provides:
 - `gitconfig.symlink`: Main Git configuration file (symlinked to `~/.gitconfig`)
 - `gitignore.symlink`: Global Git ignore file (symlinked to `~/.gitignore`)
 - `identity.zsh`: Contains functions for managing Git identities
+- `../bin/git-assume`: Standalone command for switching Git identities from shells or agents
+- `../bin/git-github-auth`: Switches a repository between HTTPS and SSH GitHub auth rewrites
 - `install.sh`: Sets up the Git identity system during installation
 
 ## Managing Git Identities
@@ -34,20 +36,19 @@ The `~/.gitidentities` file should contain identity configurations in this forma
 
 ```gitconfig
 [identity "work"]
-    name = Your Work Name
-    email = your.email@work.com
+    name = Person Example
+    email = person@example.com
     signingkey = ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJi+0V3m...
 
-[identity "personal"]
-    name = Your Personal Name
-    email = your.email@personal.com
-    signingkey = ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIBl7w9A5f...
+[identity "agent"]
+    name = Agent Example
+    email = agent@example.com
 ```
 
 Each identity section includes:
 - `name`: Your display name for commits
 - `email`: Your email for commits
-- `signingkey`: The SSH public key for signing (managed in 1Password)
+- `signingkey`: Optional SSH public key for signing (managed in 1Password)
 
 ### Using Identities
 
@@ -71,8 +72,9 @@ When you run `git-assume <identity>`, it:
 
 1. Reads the identity configuration from `~/.gitidentities`
 2. Sets `user.name` and `user.email` for the current repository
-3. Configures the SSH signing key from 1Password
-4. Enables commit signing automatically
+3. Configures the SSH signing key from 1Password and enables commit signing when `signingkey` is present
+4. Clears `user.signingkey` and disables commit signing when `signingkey` is omitted
+5. Uses worktree-local config in linked worktrees that have `extensions.worktreeConfig=true`
 
 This allows for seamless switching between different GitHub/Git accounts while maintaining proper commit attribution and signing.
 

git/gitconfig.symlink

@@ -59,12 +59,9 @@
 [gpg "ssh"]
   program = /Applications/1Password.app/Contents/MacOS/op-ssh-sign
 
-[url "git@github.com:lox/"]
-  insteadOf = https://github.com/lox/
-  insteadOf = github.com/lox/
 [credential "https://github.com"]
 	helper =
-	helper = !gh auth git-credential
+	helper = !/opt/homebrew/bin/gh auth git-credential
 [credential "https://gist.github.com"]
 	helper =
-	helper = !gh auth git-credential
+	helper = !/opt/homebrew/bin/gh auth git-credential

git/identity.zsh

@@ -6,26 +6,5 @@ git-identities() {
 }
 
 git-assume() {
-  local identity="$1"
-  local name
-  local email
-
-  if ! name=$(git config "identity.$identity.name") ; then
-    echo "Missing name for $identity"
-    return 1
-  fi
-
-  if ! email=$(git config "identity.$identity.email") ; then
-    echo "Missing email for $identity"
-    return 1
-  fi
-
-  git config user.identity "$identity"
-  git config user.name "$name"
-  git config user.email "$email"
-
-  if signingkey=$(git config "identity.$identity.signingkey") ; then
-    git config user.signingkey "$signingkey"
-    git config commit.gpgsign true
-  fi
+  command git-assume "$@"
 }