A simple command that creates a new cmux workspace for a new git worktree, then creates a new Claude session

new-feature.sh

#!/usr/bin/env bash
# new-feature — create a cmux workspace + git worktree + claude session
set -e

# ── 1. Prompt ────────────────────────────────────────────────────────────────
read -rp "Feature name: " FEATURE_NAME
[[ -z "$FEATURE_NAME" ]] && { echo "Error: feature name required"; exit 1; }

# ── 2. Derive branch slug ────────────────────────────────────────────────────
SLUG=$(echo "$FEATURE_NAME" \
  | tr '[:upper:]' '[:lower:]' \
  | sed 's/[^a-z0-9]/-/g' \
  | sed 's/-\+/-/g' \
  | sed 's/^-//;s/-$//')
BRANCH="feature/$SLUG"

# ── 3. Resolve git root ──────────────────────────────────────────────────────
GIT_ROOT=$(git rev-parse --show-toplevel 2>/dev/null) \
  || { echo "Error: not inside a git repository"; exit 1; }
WORKTREE_DIR="$GIT_ROOT/.worktrees/$SLUG"

# ── 4. Ensure .worktrees/ is gitignored ─────────────────────────────────────
if ! git -C "$GIT_ROOT" check-ignore -q .worktrees 2>/dev/null; then
  echo ".worktrees/" >> "$GIT_ROOT/.gitignore"
  echo "Added .worktrees/ to .gitignore"
fi

# ── 5. Create git worktree ───────────────────────────────────────────────────
git -C "$GIT_ROOT" worktree add "$WORKTREE_DIR" -b "$BRANCH"
echo "Worktree: $WORKTREE_DIR  (branch: $BRANCH)"

# ── 6. Create cmux workspace (--cwd and --command handle everything) ─────────
WORKSPACE_OUTPUT=$(cmux new-workspace \
  --cwd "$WORKTREE_DIR" \
  --command "claude --dangerously-skip-permissions")

# Parse full workspace ref from "OK workspace:N" (e.g. "workspace:2")
WORKSPACE_ID=$(echo "$WORKSPACE_OUTPUT" | grep -oE 'workspace:[0-9]+')

# ── 7. Rename the NEW workspace by targeting it explicitly with --workspace ───
if [[ -n "$WORKSPACE_ID" ]]; then
  cmux rename-workspace --workspace "$WORKSPACE_ID" "$FEATURE_NAME"
fi

echo "Opened cmux workspace \"$FEATURE_NAME\" → $WORKTREE_DIR"