diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..3d26fa0
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,23 @@
+# http://editorconfig.org
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.json]
+insert_final_newline = ignore
+
+[Makefile]
+indent_style = tab
+
+# Shell scripts — shfmt reads these properties
+[*.sh]
+switch_case_indent = true
+
+[*.md]
+trim_trailing_whitespace = false
diff --git a/.github/workflows/check.yaml b/.github/workflows/check.yaml
new file mode 100644
index 0000000..9a0b7d1
--- /dev/null
+++ b/.github/workflows/check.yaml
@@ -0,0 +1,57 @@
+name: check
+
+on:
+  push:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref == 'refs/heads/main' && github.sha || github.ref }}
+  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Find bash scripts
+        id: find-bash
+        run: |
+          bash_files=""
+          # .sh files with bash shebangs
+          for f in $(find . -name '*.sh' -not -path './.git/*' -not -path './node_modules/*'); do
+            shebang=$(head -1 "$f")
+            if echo "$shebang" | grep -qE '(bash|^#!/bin/sh)'; then
+              bash_files="$bash_files $f"
+            fi
+          done
+          # bin/ scripts without .sh extension
+          for f in $(find ./bin -maxdepth 1 -type f -not -name '*.sh' -not -path './.git/*'); do
+            shebang=$(head -1 "$f")
+            if echo "$shebang" | grep -qE '(bash|^#!/bin/sh)'; then
+              bash_files="$bash_files $f"
+            fi
+          done
+          echo "files=$bash_files" >> "$GITHUB_OUTPUT"
+          echo "Found bash files:$bash_files"
+
+      - name: ShellCheck
+        if: steps.find-bash.outputs.files != ''
+        run: |
+          bash_files="${{ steps.find-bash.outputs.files }}"
+          echo "Running ShellCheck on:$bash_files"
+          shellcheck $bash_files
+
+      - name: shfmt check
+        if: steps.find-bash.outputs.files != ''
+        run: |
+          bash_files="${{ steps.find-bash.outputs.files }}"
+          echo "Running shfmt on:$bash_files"
+          # -d shows diff; indent settings sourced from .editorconfig
+          shfmt -d $bash_files
+
+      - name: EditorConfig check
+        uses: editorconfig-checker/action-editorconfig-checker@main
+
+      - name: Run editorconfig-checker
+        run: editorconfig-checker
diff --git a/.shellcheckrc b/.shellcheckrc
new file mode 100644
index 0000000..144a3e1
--- /dev/null
+++ b/.shellcheckrc
@@ -0,0 +1,11 @@
+# ShellCheck configuration for nsheaps/git-wt
+# https://www.shellcheck.net/wiki/
+
+# Default shell dialect — all scripts in this repo are bash.
+shell=bash
+
+# SC1091: Not following sourced files — sourced paths are dynamic
+disable=SC1091
+
+# SC2034: Variable appears unused — some variables are used in tests or exported
+disable=SC2034
diff --git a/bin/git-wt b/bin/git-wt
index 0a08b5a..2a84013 100755
--- a/bin/git-wt
+++ b/bin/git-wt
@@ -60,10 +60,10 @@ SCAN_DIR="${HOME}/src"
 TARGET_BRANCH=""
 DELETE_MODE=false
 FORCE_DELETE=false
-EXEC_SHELL=""  # Empty means use default based on context
+EXEC_SHELL="" # Empty means use default based on context
 UPDATE_CHECK_FILE="/tmp/git-wt-update-check-$$"
 PR_CACHE_DIR="/tmp/git-wt-pr-cache-$$"
-export PR_CACHE_DIR  # Export for fzf preview subshell
+export PR_CACHE_DIR # Export for fzf preview subshell
 
 # Detect if running interactively (TTY on stdin)
 IS_INTERACTIVE=false
@@ -98,9 +98,9 @@ check_for_updates() {
     if [[ -n "$latest_version" ]] && [[ "$latest_version" != "$current_version" ]]; then
       # Simple version comparison - check if latest is newer
       # This works for semver: compare as strings after normalizing
-      if [[ "$(printf '%s\n%s' "$current_version" "$latest_version" | sort -V | tail -1)" == "$latest_version" ]] && \
-         [[ "$current_version" != "$latest_version" ]]; then
-        echo "UPDATE_AVAILABLE=$latest_version" > "$UPDATE_CHECK_FILE"
+      if [[ "$(printf '%s\n%s' "$current_version" "$latest_version" | sort -V | tail -1)" == "$latest_version" ]] &&
+        [[ "$current_version" != "$latest_version" ]]; then
+        echo "UPDATE_AVAILABLE=$latest_version" >"$UPDATE_CHECK_FILE"
       fi
     fi
   fi
@@ -142,26 +142,44 @@ show_help() {
 
 while [[ $# -gt 0 ]]; do
   case "$1" in
-    --scan-dir) SCAN_DIR="$2"; shift 2 ;;
-    --exec) EXEC_SHELL="yes"; shift ;;
-    --no-exec) EXEC_SHELL="no"; shift ;;
-    --force) FORCE_DELETE=true; shift ;;
-    -h|--help) show_help ;;
-    -v|--version) echo "git-wt $(get_version)"; exit 0 ;;
-    d)
-      DELETE_MODE=true
-      shift
-      # Next arg should be the branch name
-      if [[ $# -gt 0 ]] && [[ "$1" != -* ]]; then
-        TARGET_BRANCH="$1"
-        shift
-      fi
-      ;;
-    -*) echo "Unknown option: $1" >&2; show_help ;;
-    *)
+  --scan-dir)
+    SCAN_DIR="$2"
+    shift 2
+    ;;
+  --exec)
+    EXEC_SHELL="yes"
+    shift
+    ;;
+  --no-exec)
+    EXEC_SHELL="no"
+    shift
+    ;;
+  --force)
+    FORCE_DELETE=true
+    shift
+    ;;
+  -h | --help) show_help ;;
+  -v | --version)
+    echo "git-wt $(get_version)"
+    exit 0
+    ;;
+  d)
+    DELETE_MODE=true
+    shift
+    # Next arg should be the branch name
+    if [[ $# -gt 0 ]] && [[ "$1" != -* ]]; then
       TARGET_BRANCH="$1"
       shift
-      ;;
+    fi
+    ;;
+  -*)
+    echo "Unknown option: $1" >&2
+    show_help
+    ;;
+  *)
+    TARGET_BRANCH="$1"
+    shift
+    ;;
   esac
 done
 
@@ -170,9 +188,9 @@ done
 # Interactive mode (no args, TTY): default to exec (spawn shell)
 if [[ -z "$EXEC_SHELL" ]]; then
   if [[ -n "$TARGET_BRANCH" ]]; then
-    EXEC_SHELL="no"  # CLI mode: print path by default
+    EXEC_SHELL="no" # CLI mode: print path by default
   else
-    EXEC_SHELL="yes"  # Interactive mode: spawn shell by default
+    EXEC_SHELL="yes" # Interactive mode: spawn shell by default
   fi
 fi
 
@@ -181,8 +199,8 @@ check_tool() {
   if ! command -v "$1" &>/dev/null; then
     echo "Error: $1 is required but not installed" >&2
     case "$1" in
-      fzf) echo "Install with: brew install fzf" >&2 ;;
-      gum) echo "Install with: brew install gum" >&2 ;;
+    fzf) echo "Install with: brew install fzf" >&2 ;;
+    gum) echo "Install with: brew install gum" >&2 ;;
     esac
     exit 1
   fi
@@ -207,7 +225,7 @@ confirm() {
 input_prompt() {
   local placeholder="${1:-Enter value}"
   local result
-  result=$(fzf --print-query --header="$placeholder" --height=3 --no-info < /dev/null 2>/dev/null | head -1)
+  result=$(fzf --print-query --header="$placeholder" --height=3 --no-info </dev/null 2>/dev/null | head -1)
   echo "$result"
 }
 
@@ -407,7 +425,8 @@ select_repo() {
 switch_to_branch() {
   local branch="$1"
   local git_root="$2"
-  local repo_name=$(basename "$git_root")
+  local repo_name
+  repo_name=$(basename "$git_root")
 
   # Check if branch exists locally
   local branch_exists_local=false
@@ -424,14 +443,17 @@ switch_to_branch() {
   fi
 
   # Determine worktree path
-  local safe_branch=$(echo "$branch" | tr '/' '-')
+  local safe_branch
+  safe_branch=$(echo "$branch" | tr '/' '-')
   local worktree_path="../${repo_name}.worktrees/${safe_branch}"
 
   # Check if worktree already exists
   local existing_worktree=""
   while IFS= read -r line; do
-    local wt_path=$(echo "$line" | cut -d' ' -f1)
-    local wt_branch=$(git -C "$wt_path" branch --show-current 2>/dev/null || echo "")
+    local wt_path
+    wt_path=$(echo "$line" | cut -d' ' -f1)
+    local wt_branch
+    wt_branch=$(git -C "$wt_path" branch --show-current 2>/dev/null || echo "")
     if [[ "$wt_branch" == "$branch" ]]; then
       existing_worktree="$wt_path"
       break
@@ -460,7 +482,8 @@ switch_to_branch() {
     echo "Branch: $branch (tracking $remote_ref)"
   else
     # Branch doesn't exist - create new branch
-    local default_branch=$(git -C "$git_root" symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@' || echo "main")
+    local default_branch
+    default_branch=$(git -C "$git_root" symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@' || echo "main")
     local base_branch="$default_branch"
 
     if [[ "$IS_INTERACTIVE" == "true" ]]; then
@@ -469,7 +492,8 @@ switch_to_branch() {
 
       # Ask what to base it on
       local base_options=("$default_branch (default)" "other...")
-      local base_selected=$(printf '%s\n' "${base_options[@]}" | fzf --header="Create new branch based on:" --height=5 --no-info)
+      local base_selected
+      base_selected=$(printf '%s\n' "${base_options[@]}" | fzf --header="Create new branch based on:" --height=5 --no-info)
 
       if [[ "$base_selected" == "other..."* ]]; then
         base_branch=$(git -C "$git_root" branch -a --format='%(refname:short)' | fzf --prompt="Select base branch> ")
@@ -556,7 +580,7 @@ fi
 
 # Setup for PR preview caching
 mkdir -p "$PR_CACHE_DIR"
-export GIT_ROOT  # Export for fzf preview subshell
+export GIT_ROOT # Export for fzf preview subshell
 
 # If branch specified via CLI, create/switch to that worktree
 if [[ -n "$TARGET_BRANCH" ]]; then
@@ -647,13 +671,15 @@ MENU_OPTIONS+=("🔄 (switch repository)")
 # Show selection menu with fzf
 # Preview shows PR info from cache, falls back to single fetch if not cached yet
 KEY_PRESSED=""
-FZF_RESULT=$(printf '%s\n' "${MENU_OPTIONS[@]}" | fzf \
-  --style=full \
-  --expect=d \
-  --no-sort \
-  --header="enter=select, d=delete worktree" \
-  --prompt="Select or create worktree> " \
-  --preview='
+# shellcheck disable=SC2016
+FZF_RESULT=$(
+  printf '%s\n' "${MENU_OPTIONS[@]}" | fzf \
+    --style=full \
+    --expect=d \
+    --no-sort \
+    --header="enter=select, d=delete worktree" \
+    --prompt="Select or create worktree> " \
+    --preview='
     item={}
     # Extract branch name from different formats
     if [[ "$item" == "📂 [worktree]"* ]] || [[ "$item" == "🏠 [root]"* ]]; then
@@ -684,7 +710,8 @@ FZF_RESULT=$(printf '%s\n' "${MENU_OPTIONS[@]}" | fzf \
       echo "No PR found for branch: $branch"
     fi
   ' \
-  --preview-window=right:50%:wrap)
+    --preview-window=right:50%:wrap
+)
 KEY_PRESSED=$(echo "$FZF_RESULT" | head -1)
 SELECTED=$(echo "$FZF_RESULT" | tail -1)
 
@@ -704,6 +731,7 @@ if [[ "$KEY_PRESSED" == "d" ]]; then
   fi
 
   # Extract worktree path
+  # shellcheck disable=SC2001
   WT_PATH=$(echo "$SELECTED" | sed 's/.*→ //')
   WT_BRANCH=$(echo "$SELECTED" | sed 's/📂 \[worktree\] //' | sed 's/ →.*//')
 
@@ -739,90 +767,92 @@ fi
 
 # Handle selection
 case "$SELECTED" in
-  "📁 (create new worktree)")
-    # Get branch name
-    BRANCH_NAME=$(input_prompt "Enter new branch name")
-    if [[ -z "$BRANCH_NAME" ]]; then
-      echo "Cancelled"
-      exit 0
-    fi
+"📁 (create new worktree)")
+  # Get branch name
+  BRANCH_NAME=$(input_prompt "Enter new branch name")
+  if [[ -z "$BRANCH_NAME" ]]; then
+    echo "Cancelled"
+    exit 0
+  fi
 
-    # Ask for base branch
-    CURRENT_BRANCH=$(git -C "$GIT_ROOT" branch --show-current)
-    DEFAULT_BRANCH=$(git -C "$GIT_ROOT" symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@' || echo "main")
+  # Ask for base branch
+  CURRENT_BRANCH=$(git -C "$GIT_ROOT" branch --show-current)
+  DEFAULT_BRANCH=$(git -C "$GIT_ROOT" symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@' || echo "main")
 
-    BASE_OPTIONS=("$DEFAULT_BRANCH (default)" "$CURRENT_BRANCH (current)" "other...")
-    BASE_SELECTED=$(printf '%s\n' "${BASE_OPTIONS[@]}" | fzf --header="Base branch:" --height=6 --no-info)
+  BASE_OPTIONS=("$DEFAULT_BRANCH (default)" "$CURRENT_BRANCH (current)" "other...")
+  BASE_SELECTED=$(printf '%s\n' "${BASE_OPTIONS[@]}" | fzf --header="Base branch:" --height=6 --no-info)
 
-    case "$BASE_SELECTED" in
-      *"(default)"*) BASE_BRANCH="$DEFAULT_BRANCH" ;;
-      *"(current)"*) BASE_BRANCH="$CURRENT_BRANCH" ;;
-      *) BASE_BRANCH=$(git -C "$GIT_ROOT" branch -a --format='%(refname:short)' | fzf --prompt="Select base branch> ") ;;
-    esac
+  case "$BASE_SELECTED" in
+  *"(default)"*) BASE_BRANCH="$DEFAULT_BRANCH" ;;
+  *"(current)"*) BASE_BRANCH="$CURRENT_BRANCH" ;;
+  *) BASE_BRANCH=$(git -C "$GIT_ROOT" branch -a --format='%(refname:short)' | fzf --prompt="Select base branch> ") ;;
+  esac
 
-    # Create worktree path
-    SAFE_BRANCH=$(echo "$BRANCH_NAME" | tr '/' '-')
-    WORKTREE_PATH="../${REPO_NAME}.worktrees/${SAFE_BRANCH}"
+  # Create worktree path
+  SAFE_BRANCH=$(echo "$BRANCH_NAME" | tr '/' '-')
+  WORKTREE_PATH="../${REPO_NAME}.worktrees/${SAFE_BRANCH}"
 
-    # Create the worktree
-    mkdir -p "$(dirname "$GIT_ROOT/$WORKTREE_PATH")"
-    git -C "$GIT_ROOT" worktree add -b "$BRANCH_NAME" "$WORKTREE_PATH" "$BASE_BRANCH"
+  # Create the worktree
+  mkdir -p "$(dirname "$GIT_ROOT/$WORKTREE_PATH")"
+  git -C "$GIT_ROOT" worktree add -b "$BRANCH_NAME" "$WORKTREE_PATH" "$BASE_BRANCH"
 
-    FINAL_PATH="$(cd "$GIT_ROOT/$WORKTREE_PATH" && pwd)"
-    echo ""
-    echo "Created worktree at: $FINAL_PATH"
-    echo "Branch: $BRANCH_NAME (based on $BASE_BRANCH)"
-    ;;
-
-  "🏠 [root]"*)
-    # Extract path from selection
-    FINAL_PATH=$(echo "$SELECTED" | sed 's/.*→ //')
-    echo ""
-    echo "Selected root checkout: $FINAL_PATH"
-    ;;
+  FINAL_PATH="$(cd "$GIT_ROOT/$WORKTREE_PATH" && pwd)"
+  echo ""
+  echo "Created worktree at: $FINAL_PATH"
+  echo "Branch: $BRANCH_NAME (based on $BASE_BRANCH)"
+  ;;
+
+"🏠 [root]"*)
+  # Extract path from selection
+  # shellcheck disable=SC2001
+  FINAL_PATH=$(echo "$SELECTED" | sed 's/.*→ //')
+  echo ""
+  echo "Selected root checkout: $FINAL_PATH"
+  ;;
 
-  "📂 [worktree]"*)
-    # Extract path from selection
-    FINAL_PATH=$(echo "$SELECTED" | sed 's/.*→ //')
-    echo ""
-    echo "Selected worktree: $FINAL_PATH"
-    ;;
+"📂 [worktree]"*)
+  # Extract path from selection
+  # shellcheck disable=SC2001
+  FINAL_PATH=$(echo "$SELECTED" | sed 's/.*→ //')
+  echo ""
+  echo "Selected worktree: $FINAL_PATH"
+  ;;
+
+"🔄 (switch repository)")
+  # Reset and re-run with repo selection
+  NEW_REPO=$(select_repo)
+  if [[ -n "$NEW_REPO" ]] && [[ -d "$NEW_REPO" ]]; then
+    exec "$0" --scan-dir "$SCAN_DIR"
+  fi
+  ;;
 
-  "🔄 (switch repository)")
-    # Reset and re-run with repo selection
-    NEW_REPO=$(select_repo)
-    if [[ -n "$NEW_REPO" ]] && [[ -d "$NEW_REPO" ]]; then
-      exec "$0" --scan-dir "$SCAN_DIR"
-    fi
-    ;;
+*)
+  # Selected an existing branch - create worktree for it
+  BRANCH_NAME="$SELECTED"
 
-  *)
-    # Selected an existing branch - create worktree for it
-    BRANCH_NAME="$SELECTED"
+  SAFE_BRANCH=$(echo "$BRANCH_NAME" | tr '/' '-')
+  WORKTREE_PATH="../${REPO_NAME}.worktrees/${SAFE_BRANCH}"
 
-    SAFE_BRANCH=$(echo "$BRANCH_NAME" | tr '/' '-')
-    WORKTREE_PATH="../${REPO_NAME}.worktrees/${SAFE_BRANCH}"
+  if [[ -d "$GIT_ROOT/$WORKTREE_PATH" ]]; then
+    FINAL_PATH="$(cd "$GIT_ROOT/$WORKTREE_PATH" && pwd)"
+    echo "Worktree already exists at: $FINAL_PATH"
+  else
+    mkdir -p "$(dirname "$GIT_ROOT/$WORKTREE_PATH")"
 
-    if [[ -d "$GIT_ROOT/$WORKTREE_PATH" ]]; then
-      FINAL_PATH="$(cd "$GIT_ROOT/$WORKTREE_PATH" && pwd)"
-      echo "Worktree already exists at: $FINAL_PATH"
+    # Check if branch exists locally or only on remote
+    if git -C "$GIT_ROOT" show-ref --verify --quiet "refs/heads/$BRANCH_NAME" 2>/dev/null; then
+      git -C "$GIT_ROOT" worktree add "$WORKTREE_PATH" "$BRANCH_NAME"
+    elif git -C "$GIT_ROOT" show-ref --verify --quiet "refs/remotes/origin/$BRANCH_NAME" 2>/dev/null; then
+      git -C "$GIT_ROOT" worktree add --track -b "$BRANCH_NAME" "$WORKTREE_PATH" "origin/$BRANCH_NAME"
     else
-      mkdir -p "$(dirname "$GIT_ROOT/$WORKTREE_PATH")"
-
-      # Check if branch exists locally or only on remote
-      if git -C "$GIT_ROOT" show-ref --verify --quiet "refs/heads/$BRANCH_NAME" 2>/dev/null; then
-        git -C "$GIT_ROOT" worktree add "$WORKTREE_PATH" "$BRANCH_NAME"
-      elif git -C "$GIT_ROOT" show-ref --verify --quiet "refs/remotes/origin/$BRANCH_NAME" 2>/dev/null; then
-        git -C "$GIT_ROOT" worktree add --track -b "$BRANCH_NAME" "$WORKTREE_PATH" "origin/$BRANCH_NAME"
-      else
-        git -C "$GIT_ROOT" worktree add "$WORKTREE_PATH" "$BRANCH_NAME"
-      fi
-      FINAL_PATH="$(cd "$GIT_ROOT/$WORKTREE_PATH" && pwd)"
-      echo "Created worktree at: $FINAL_PATH"
+      git -C "$GIT_ROOT" worktree add "$WORKTREE_PATH" "$BRANCH_NAME"
     fi
+    FINAL_PATH="$(cd "$GIT_ROOT/$WORKTREE_PATH" && pwd)"
+    echo "Created worktree at: $FINAL_PATH"
+  fi
 
-    echo "Branch: $BRANCH_NAME"
-    ;;
+  echo "Branch: $BRANCH_NAME"
+  ;;
 esac
 
 # Change to worktree directory and start new shell
diff --git a/mise.toml b/mise.toml
index 6207403..ee7bb1e 100644
--- a/mise.toml
+++ b/mise.toml
@@ -7,10 +7,18 @@ description = "Run CLI tests"
 run = "bash test/cli-test.sh"
 
 [tasks.lint]
-description = "Check bash syntax"
-run = "bash -n bin/git-wt"
+description = "Run ShellCheck on all bash scripts"
+run = "shellcheck bin/git-wt test/cli-test.sh"
+
+[tasks.fmt]
+description = "Format all bash scripts with shfmt"
+run = "shfmt -w bin/git-wt test/cli-test.sh"
+
+[tasks.fmt-check]
+description = "Check formatting of all bash scripts"
+run = "shfmt -d bin/git-wt test/cli-test.sh"
 
 [tasks.check]
-description = "Run all checks (lint + test)"
-depends = ["lint", "test"]
+description = "Run all checks (lint + fmt-check + test)"
+depends = ["lint", "fmt-check", "test"]
 run = "echo 'All checks passed'"
diff --git a/test/cli-test.sh b/test/cli-test.sh
index 3016bc2..e5eb3a9 100755
--- a/test/cli-test.sh
+++ b/test/cli-test.sh
@@ -24,7 +24,7 @@ setup() {
   cd "$TEST_DIR/test-repo"
   git config user.email "test@test.com"
   git config user.name "Test User"
-  echo "initial" > README.md
+  echo "initial" >README.md
   git add README.md
   git commit -m "Initial commit" >/dev/null 2>&1