From d579c1208007658ca50759e5e5206136db8e11a1 Mon Sep 17 00:00:00 2001
From: Timothy Allen <tim@treehouse.org.za>
Date: Fri, 16 Oct 2026 18:11:57 +0200
Subject: [PATCH] Harden isolate

---
 isolate | 96 ++++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 68 insertions(+), 28 deletions(-)

diff --git a/isolate b/isolate
index afc4b0c..2e6c2d3 100755
--- a/isolate
+++ b/isolate
@@ -1,34 +1,44 @@
-#/bin/bash
+#!/bin/bash
 
-project_dir=$( pwd )
+project_dir=$( pwd -P ) || exit 1
+home_dir=$( readlink -e -- "${HOME}" ) || exit 1
 
-bubblewrap=$( command -v bwrap )
+if ! bubblewrap=$( command -v bwrap ); then
+  echo "bubblewrap (bwrap) is required" >&2
+  exit 1
+fi
 agents=(
   $( command -v claude )
+  $( command -v codex )
   $( command -v pi )
   $( command -v ps ) # for testing
+  $( command -v ls ) # for testing
+  $( command -v touch ) # for testing
+  $( command -v bash ) # for testing
 )
 
-if [[ "${project_dir}" = "${HOME}" ]]; then
-     echo "Not running in ${HOME}"
-     exit
+if [[ "${project_dir}" = "${home_dir}" ]]; then
+     echo "Not running in ${HOME}" >&2
+     exit 1
 fi
 
 if [[ -n "${1}" ]] && [[ -n $( command -v "${1}" ) ]]; then
 	coder=$( command -v "${1}" ) && shift
-        args="${@}"
 else
-	echo "Please specify a coding agent"
-	exit
+	echo "Please specify a coding agent" >&2
+	exit 1
 fi
 
 if ! [[ " ${agents[@]} " =~ " ${coder} " ]]; then
-	echo "No agent found"
-	exit
+	echo "No agent found" >&2
+	exit 1
 fi
 
 declare -a ro_binds
-declare -a binds
+declare -a rw_binds
+declare -a bwrap_args
+declare -a bind_sources
+declare -a bind_destinations
 
 ro_binds=(
   /usr
@@ -40,32 +50,62 @@ ro_binds=(
   /etc/ssl
   /etc/passwd
   /etc/group
+  "${HOME}/sources"
 )
 
-for loc in "${HOME}/.gitconfig" "${HOME}/.local"; do
-  if [[ -e "${loc}" ]]; then
-    ro_binds+=("${loc}")
+for readonly_path in "${HOME}/.gitconfig" "${HOME}/bin" "${HOME}/.local" "${HOME}/.atuin" "${XDG_RUNTIME_DIR}"; do
+  if [[ -e "${readonly_path}" ]]; then
+    ro_binds+=("${readonly_path}")
   fi
 done
 
-binds=()
-
-for loc in "${HOME}/.claude" "${HOME}/.pi" "${project_dir}"; do
-  if [[ -e "${loc}" ]]; then
-    binds+=("${loc}")
+for readwrite_path in "${HOME}/.claude" "${HOME}/.claude.json" "${HOME}/.local/share/claude" "${HOME}/.pi" "${project_dir}"; do
+  if [[ -e "${readwrite_path}" ]]; then
+    rw_binds+=("${readwrite_path}")
   fi
 done
 
-for i in "${!ro_binds[@]}"; do
-  ro_binds["${i}"]="--ro-bind ${ro_binds[${i}]} ${ro_binds[${i}]}"
+# Resolve mount sources, but keep the paths applications expect as destinations.
+for readonly_path in "${ro_binds[@]}"; do
+  bind_source=$( readlink -e -- "${readonly_path}" ) || exit 1
+  bwrap_args+=("--ro-bind" "${bind_source}" "${readonly_path}")
+  bind_sources+=("${bind_source}")
+  bind_destinations+=("${readonly_path}")
 done
-for i in "${!binds[@]}"; do
-  binds["${i}"]="--bind ${binds[${i}]} ${binds[${i}]}"
+for readwrite_path in "${rw_binds[@]}"; do
+  bind_source=$( readlink -e -- "${readwrite_path}" ) || exit 1
+  bwrap_args+=("--bind" "${bind_source}" "${readwrite_path}")
+  bind_sources+=("${bind_source}")
+  bind_destinations+=("${readwrite_path}")
 done
 
-${bubblewrap} \
-     ${ro_binds[@]} \
-     ${binds[@]} \
+git_config="${project_dir}/.git/config"
+git_worktree_config="${project_dir}/.git/config.worktree"
+if [[ -f "${project_dir}/.git" ]]; then
+  # Linked worktrees keep their shared and per-worktree config elsewhere.
+  git_config=$( git -C "${project_dir}" rev-parse --path-format=absolute --git-path config ) || exit 1
+  git_worktree_config=$( git -C "${project_dir}" rev-parse --path-format=absolute --git-path config.worktree ) || exit 1
+fi
+
+# Mask secrets after all directory mounts so later binds cannot expose them.
+for hide_path in "${git_config}" "${git_worktree_config}" "${project_dir}/.env"; do
+  if [[ -e "${hide_path}" ]]; then
+    hide_path=$( readlink -e -- "${hide_path}" ) || exit 1
+    bwrap_args+=("--ro-bind" /dev/null "${hide_path}")
+    # A symlinked mount can expose the same file at another destination.
+    for i in "${!bind_sources[@]}"; do
+      if [[ "${hide_path}" = "${bind_sources[${i}]}" || "${hide_path}" = "${bind_sources[${i}]}/"* ]]; then
+        mask_path="${bind_destinations[${i}]}${hide_path#"${bind_sources[${i}]}"}"
+        if [[ "${mask_path}" != "${hide_path}" ]]; then
+          bwrap_args+=("--ro-bind" /dev/null "${mask_path}")
+        fi
+      fi
+    done
+  fi
+done
+
+"${bubblewrap}" \
+     "${bwrap_args[@]}" \
      --tmpfs /tmp \
      --proc /proc \
      --dev /dev \
@@ -73,4 +113,4 @@ ${bubblewrap} \
      --unshare-pid \
      --die-with-parent \
      --chdir "${project_dir}" \
-     "$( command -v ${coder} )" "${args}"
+     "${coder}" "${@}"