diff --git a/scripts/bootstrap.sh b/scripts/bootstrap.sh
new file mode 100755
index 000000000..7775f42e6
--- /dev/null
+++ b/scripts/bootstrap.sh
@@ -0,0 +1,129 @@
+#!/usr/bin/env bash
+# MSD Core bootstrap — one-line install from the public repo.
+#
+#   curl -fsSL https://msd.golem15.com | bash
+#   curl -fsSL https://msd.golem15.com | bash -s -- --codex --profile standard
+#
+# Clones (or updates) the MSD checkout into $MSD_HOME, builds it, and runs
+# bin/install.js globally for the chosen runtime(s). Installs Claude Code
+# first when it is the target runtime and `claude` is not on PATH.
+#
+# Everything lives inside main() so a truncated download never runs half a script.
+
+main() {
+  set -euo pipefail
+
+  local repo="${MSD_REPO:-https://git.golem15.com/golem15/msd-core.git}"
+  local ref="${MSD_REF:-next}"
+  local home_dir="${MSD_HOME:-$HOME/.local/share/msd-core}"
+  local profile="${MSD_PROFILE:-full}"
+  local install_claude=true
+  local runtimes=()
+
+  while (($#)); do
+    case "$1" in
+      --claude|--codex|--opencode|--cursor|--zcode|--antigravity) runtimes+=("$1") ;;
+      --profile)
+        shift
+        (($#)) || { echo "ERROR: --profile requires a value." >&2; exit 2; }
+        profile="$1"
+        ;;
+      --profile=*) profile="${1#--profile=}" ;;
+      --ref)
+        shift
+        (($#)) || { echo "ERROR: --ref requires a value." >&2; exit 2; }
+        ref="$1"
+        ;;
+      --skip-claude-install) install_claude=false ;;
+      -h|--help)
+        cat <<'EOF'
+MSD Core bootstrap
+
+Usage: curl -fsSL https://msd.golem15.com | bash -s -- [options]
+
+Options:
+  --claude, --codex, --opencode, --cursor, --zcode, --antigravity
+                         Runtime(s) to install for (default: --claude)
+  --profile NAME         Skill profile: core, standard or full (default: full)
+  --ref REF              Branch or tag to install (default: next)
+  --skip-claude-install  Do not install Claude Code when it is missing
+
+Environment: MSD_HOME (checkout dir, default ~/.local/share/msd-core),
+             MSD_REPO, MSD_REF, MSD_PROFILE
+EOF
+        exit 0
+        ;;
+      *) echo "ERROR: unknown argument: $1 (try --help)" >&2; exit 2 ;;
+    esac
+    shift
+  done
+  ((${#runtimes[@]})) || runtimes=(--claude)
+
+  case "$profile" in
+    core|standard|full) ;;
+    *) echo "ERROR: profile must be core, standard or full; got: $profile" >&2; exit 2 ;;
+  esac
+
+  say() { printf '\033[36m==>\033[0m %s\n' "$*"; }
+
+  command -v git >/dev/null 2>&1 || { echo "ERROR: git is required." >&2; exit 1; }
+  local node_major
+  node_major=$(node -p 'process.versions.node.split(".")[0]' 2>/dev/null || echo 0)
+  if ((node_major < 24)); then
+    cat >&2 <<EOF
+ERROR: MSD needs Node.js 24 or newer (found: $(node --version 2>/dev/null || echo none)).
+Install it, e.g. with nvm:
+  curl -fsSL https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.3/install.sh | bash
+  nvm install 24
+then rerun this command.
+EOF
+    exit 1
+  fi
+
+  if ! command -v jq >/dev/null 2>&1; then
+    printf '\033[33mWARNING:\033[0m jq is not installed; MSD workflows rely on it.\n' >&2
+    echo '         Install it (apt install jq / brew install jq) after this finishes.' >&2
+  fi
+
+  if [[ " ${runtimes[*]} " == *" --claude "* ]] && $install_claude \
+    && ! command -v claude >/dev/null 2>&1 && [[ ! -x "$HOME/.local/bin/claude" ]]; then
+    say "Installing Claude Code"
+    curl -fsSL https://claude.ai/install.sh | bash
+  fi
+
+  if [[ -d "$home_dir/.git" ]]; then
+    say "Updating $home_dir ($ref)"
+    if [[ -n "$(git -C "$home_dir" status --porcelain --untracked-files=no)" ]]; then
+      echo "ERROR: $home_dir has local changes; commit or discard them first." >&2
+      exit 1
+    fi
+    git -C "$home_dir" fetch --quiet origin "$ref"
+    git -C "$home_dir" checkout --quiet --detach FETCH_HEAD
+  else
+    say "Cloning MSD into $home_dir ($ref)"
+    mkdir -p "$(dirname "$home_dir")"
+    git clone --quiet --branch "$ref" "$repo" "$home_dir"
+  fi
+
+  cd "$home_dir"
+  say "Installing dependencies and building"
+  npm ci --no-audit --no-fund --loglevel=error
+  npm run --silent build:hooks
+
+  local rt
+  for rt in "${runtimes[@]}"; do
+    say "Installing MSD for ${rt#--} (profile: $profile)"
+    node bin/install.js "$rt" --global "--profile=$profile"
+  done
+
+  cat <<EOF
+
+MSD installed from $home_dir ($(git rev-parse --short HEAD)).
+Update any time by rerunning:  curl -fsSL https://msd.golem15.com | bash
+EOF
+  if [[ " ${runtimes[*]} " == *" --claude "* ]] && ! command -v claude >/dev/null 2>&1; then
+    echo 'Add Claude Code to your PATH:  export PATH="$HOME/.local/bin:$PATH"'
+  fi
+}
+
+main "$@"