fix(sandbox-ssh-fix): use PATH-based nc wrapper instead of replacing GIT_SSH_COMMAND

sandbox-ssh-fix/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "sandbox-ssh-fix",
-  "version": "1.0.0",
-  "description": "Fixes git-over-SSH in the Claude Code sandbox on macOS by replacing the broken BSD nc SOCKS5 proxy with ncat",
+  "version": "1.0.1",
+  "description": "Fixes git-over-SSH in the Claude Code sandbox on macOS by wrapping BSD nc with ncat for SOCKS5 proxy auth",
   "author": {
     "name": "cblecker",
     "email": "admin@toph.ca"

sandbox-ssh-fix/README.md

@@ -13,19 +13,20 @@ Tracked upstream: <https://github.com/anthropics/claude-code/issues/70684>
 
 ## How it works
 
-A SessionStart hook detects the broken pattern and overrides `GIT_SSH_COMMAND`
-via `$CLAUDE_ENV_FILE`:
+This plugin ships an `nc` wrapper (`bin/nc`) that intercepts SOCKS5 proxy calls
+and delegates to `ncat` with the auth credentials parsed from `ALL_PROXY`.
 
-- If `ncat` is available: uses `ncat --proxy-type socks5 --proxy-auth` with
-  credentials parsed from `ALL_PROXY`
-- If `ncat` is not available: falls back to plain `ssh` (bypasses the proxy,
-  relies on the sandbox network allowlist)
+### Flow
 
-The fix only activates when all conditions are met:
+1. SessionStart hook prepends `plugin/bin/` to `PATH` via `CLAUDE_ENV_FILE`
+2. Sandbox injects `GIT_SSH_COMMAND` containing `nc -X 5 -x localhost:PORT %h %p`
+3. SSH runs ProxyCommand, shell finds `bin/nc` wrapper first via PATH
+4. Wrapper checks for the SOCKS5 pattern (`-X 5 -x`), reads `ALL_PROXY`
+   (available at runtime in sandbox), and delegates to `ncat` with `--proxy-auth`
+5. Non-SOCKS5 calls or missing `ncat` fall through to `/usr/bin/nc`
 
-1. Running inside the sandbox (`SANDBOX_RUNTIME=1`)
-2. `GIT_SSH_COMMAND` contains the broken `nc -X 5` pattern
-3. `ALL_PROXY` contains credentials (has `@`)
+The wrapper uses `127.0.0.1` instead of `localhost` because `ncat` resolves
+`localhost` differently and the connection is refused.
 
 ## Prerequisites
 
@@ -35,8 +36,8 @@ Install `ncat` (from nmap) for full SOCKS5 proxy support:
 brew install nmap
 ```
 
-Without `ncat`, the plugin falls back to direct SSH which still works but
-bypasses the sandbox's SOCKS5 proxy.
+Without `ncat`, the plugin falls back to the system `nc` which will fail for
+authenticated SOCKS5 proxies.
 
 ## License
 

sandbox-ssh-fix/bin/nc

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+if [[ "$#" -ge 6 ]] \
+  && [[ "$1" == "-X" && "$2" == "5" && "$3" == "-x" ]] \
+  && [[ "${ALL_PROXY:-}" == *"@"* ]] \
+  && command -v ncat >/dev/null 2>&1; then
+  _auth="${ALL_PROXY#*://}"
+  _auth="${_auth%@*}"
+  _proxy="${4/localhost/127.0.0.1}"
+  exec ncat --proxy-type socks5 --proxy-auth "$_auth" --proxy "$_proxy" "${@: -2}"
+fi
+exec /usr/bin/nc "$@"

sandbox-ssh-fix/scripts/fix-git-ssh.sh

@@ -1,29 +1,7 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-# Only run inside the Claude Code sandbox
-[[ "${SANDBOX_RUNTIME:-}" == "1" ]] || exit 0
-
-# Only fix the broken BSD nc SOCKS5 proxy pattern
-[[ "${GIT_SSH_COMMAND:-}" == *"nc -X 5"* ]] || exit 0
-
-# Only needed when ALL_PROXY has credentials (contains @)
-[[ "${ALL_PROXY:-}" == *"@"* ]] || exit 0
-
-# CLAUDE_ENV_FILE is required to export the fix
 [[ -n "${CLAUDE_ENV_FILE:-}" ]] || exit 0
 
-# Parse ALL_PROXY: socks5h://user:pass@host:port
-proxy_auth="${ALL_PROXY#*://}"  # user:pass@host:port
-proxy_auth="${proxy_auth%@*}"   # user:pass
-proxy_port="${ALL_PROXY##*:}"   # port
-
-if command -v ncat >/dev/null 2>&1; then
-  cat >> "${CLAUDE_ENV_FILE}" <<ENVEOF
-export GIT_SSH_COMMAND='ssh -o ControlMaster=no -o ControlPath=none -o '\''ProxyCommand=ncat --proxy-type socks5 --proxy-auth ${proxy_auth} --proxy 127.0.0.1:${proxy_port} %h %p'\'''
-ENVEOF
-  echo "SessionStart:startup hook success: sandbox-ssh-fix: replaced broken BSD nc with ncat for SOCKS5 proxy auth"
-else
-  echo "export GIT_SSH_COMMAND='ssh -o ControlMaster=no -o ControlPath=none'" >> "${CLAUDE_ENV_FILE}"
-  echo "SessionStart:startup hook success: sandbox-ssh-fix: ncat not found, bypassing SOCKS5 proxy (using direct SSH)"
-fi
+echo "export PATH=\"${CLAUDE_PLUGIN_ROOT}/bin:\${PATH}\"" >> "${CLAUDE_ENV_FILE}"
+echo "SessionStart:startup hook success: sandbox-ssh-fix: added nc wrapper to PATH"