bub.sh

#!/usr/bin/env bash
set -euo pipefail

REPO="$(pwd)"
UID_NUM="$(id -u)"
GID_NUM="$(id -g)"
REAL_HOME="$(getent passwd "$UID_NUM" | cut -d: -f6)"

if [[ -z "$REAL_HOME" ]]; then
  echo "Failed to determine real home directory for uid $UID_NUM" >&2
  exit 1
fi

SANDBOX_HOME="$REPO/.bwrap-home"
mkdir -p "$SANDBOX_HOME"
mkdir -p "$SANDBOX_HOME/.codex"
mkdir -p "$SANDBOX_HOME/.claude"

# Share only Codex auth across repos. Keep sessions, logs, sqlite state, etc.
# project-local to avoid cross-instance conflicts.
LOCAL_AUTH="$SANDBOX_HOME/.codex/auth.json"
HOST_AUTH="$REAL_HOME/.codex/auth.json"

# Share only Claude auth across repos. Keep history, plugins, cache, etc.
# project-local to avoid cross-instance conflicts.
LOCAL_CLAUDE_AUTH="$SANDBOX_HOME/.claude/.credentials.json"
HOST_CLAUDE_AUTH="$REAL_HOME/.claude/.credentials.json"
LOCAL_CLAUDE_STATE="$SANDBOX_HOME/.claude.json"
HOST_CLAUDE_STATE="$REAL_HOME/.claude.json"
LOCAL_CLAUDE_MCP_AUTH_CACHE="$SANDBOX_HOME/.claude/mcp-needs-auth-cache.json"
HOST_CLAUDE_MCP_AUTH_CACHE="$REAL_HOME/.claude/mcp-needs-auth-cache.json"

mkdir -p "$REAL_HOME/.codex"
mkdir -p "$REAL_HOME/.claude"

# Seed the host auth file from an existing project-local sandbox auth if
# needed, so older repo-local setups can migrate forward automatically.
if [[ ! -s "$HOST_AUTH" && -e "$LOCAL_AUTH" ]]; then
  cp -a "$LOCAL_AUTH" "$HOST_AUTH"
fi

# Ensure the bind target exists even before first login.
if [[ ! -e "$HOST_AUTH" ]]; then
  : > "$HOST_AUTH"
fi

# Seed the host Claude auth file from an existing project-local sandbox auth if
# needed, so older repo-local setups can migrate forward automatically.
if [[ ! -s "$HOST_CLAUDE_AUTH" && -e "$LOCAL_CLAUDE_AUTH" ]]; then
  install -m 600 "$LOCAL_CLAUDE_AUTH" "$HOST_CLAUDE_AUTH"
fi

# Ensure the bind target exists even before first login.
if [[ ! -e "$HOST_CLAUDE_AUTH" ]]; then
  : > "$HOST_CLAUDE_AUTH"
fi

# Claude also keeps signed-in account metadata in ~/.claude.json.
if [[ ! -s "$HOST_CLAUDE_STATE" && -e "$LOCAL_CLAUDE_STATE" ]]; then
  install -m 600 "$LOCAL_CLAUDE_STATE" "$HOST_CLAUDE_STATE"
fi

if [[ ! -e "$HOST_CLAUDE_STATE" ]]; then
  : > "$HOST_CLAUDE_STATE"
fi

# Carry the MCP auth cache too so server auth prompts are shared.
if [[ ! -s "$HOST_CLAUDE_MCP_AUTH_CACHE" && -e "$LOCAL_CLAUDE_MCP_AUTH_CACHE" ]]; then
  install -m 600 "$LOCAL_CLAUDE_MCP_AUTH_CACHE" "$HOST_CLAUDE_MCP_AUTH_CACHE"
fi

if [[ ! -e "$HOST_CLAUDE_MCP_AUTH_CACHE" ]]; then
  : > "$HOST_CLAUDE_MCP_AUTH_CACHE"
fi

# Expose host ~/.local at its real absolute path so both relative symlinks and
# updater-created absolute symlinks keep working inside the sandbox.
HOSTHOME="$REAL_HOME"

args=(
  # Lifecycle + namespaces
  --die-with-parent
  --unshare-ipc
  --unshare-uts
  --unshare-cgroup

  # Optional hardening (recommended; should not break codex/node)
  --unshare-user
  --cap-drop ALL

  # Core OS (read-only)
  --ro-bind /usr /usr
  --ro-bind /lib /lib
  --ro-bind /lib64 /lib64
  --ro-bind /bin /bin
  --ro-bind /sbin /sbin

  # /etc is needed for Fedora crypto-policies + CA trust + misc config (read-only)
  --ro-bind /etc /etc

  # Fedora /etc/resolv.conf commonly points into /run/systemd/resolve/...
  --ro-bind /run/systemd/resolve /run/systemd/resolve

  # Virtual filesystems
  --proc /proc
  --dev /dev
  --tmpfs /tmp

  # Identity (keep file ownership sane in /workspace)
  --uid "$UID_NUM"
  --gid "$GID_NUM"

  # Workspace (writable)
  --bind "$REPO" /workspace
  --chdir /workspace

  # Sandbox HOME (writable, project-local)
  --bind "$SANDBOX_HOME" /home/sandbox
  --setenv HOME /home/sandbox

  # Share Codex auth only. Other ~/.codex state remains project-local.
  --bind "$HOST_AUTH" /home/sandbox/.codex/auth.json
  # Share Claude auth only. Other ~/.claude state remains project-local.
  --bind "$HOST_CLAUDE_AUTH" /home/sandbox/.claude/.credentials.json
  --bind "$HOST_CLAUDE_STATE" /home/sandbox/.claude.json
  --bind "$HOST_CLAUDE_MCP_AUTH_CACHE" /home/sandbox/.claude/mcp-needs-auth-cache.json

  # Host-installed CLI tools (read-only) at the real host path
  --dir "$HOSTHOME"
  --ro-bind "$REAL_HOME/.local" "$HOSTHOME/.local"
  --setenv PATH "$HOSTHOME/.local/bin:/usr/local/bin:/usr/bin:/bin"

  # --- Optional: make your real home readable (RO) for context ---
  # --ro-bind "$HOME" "$HOME"
  #
  # --- Optional: if you RO-mount $HOME, mask common secret dirs so they look empty ---
  # --tmpfs "$HOME/.ssh"
  # --tmpfs "$HOME/.gnupg"
  # --tmpfs "$HOME/.aws"
  # --tmpfs "$HOME/.config/gcloud"
  # --tmpfs "$HOME/.kube"
  # --tmpfs "$HOME/.netrc"

  # Make Python user-site packages resolve correctly
  --setenv PYTHONUSERBASE "$HOSTHOME/.local"

)

exec bwrap "${args[@]}" bash -i