Two separate sandbox blockers surfaced when the user tried
`pnpm work decompose --execute`:
1. **Container died on exec** — our Dockerfile had:
- WORKDIR /workspace + CMD ["bash"]
- No `agent` user (sandcastle exec's as UID:GID it built with)
- node:22-bookworm-slim (missing some build deps the install
script wants)
Sandcastle expects:
- A non-root `agent` user with home at /home/agent (sandcastle
does `git config --global --add safe.directory /home/agent/workspace`,
which fails if the user doesn't exist or the container exited)
- ENTRYPOINT ["sleep", "infinity"] so the container survives
the gap between sandcastle creating it and exec'ing in
Replaced .sandcastle/Dockerfile with the shape `sandcastle init`
would generate (verified against
node_modules/@ai-hero/sandcastle/dist/InitService.js):
- node:22-bookworm (full, not slim) for build tooling
- apt-get installs git + curl + jq
- corepack-pinned pnpm@9
- ARG AGENT_UID=1000 + AGENT_GID=1000; sandcastle's
build-image passes the host's UID/GID by default
- `groupmod -o -g $AGENT_GID node` + `usermod -o ... node` —
the `-o` (non-unique) flag is required because macOS hosts
have UID:501 GID:20, and GID 20 collides with Debian's
`dialout` group in the base image (without -o, groupmod
fails with "GID '20' already exists")
- USER ${AGENT_UID}:${AGENT_GID}, then install Claude Code CLI
via the official installer
- ENV PATH includes /home/agent/.local/bin
- WORKDIR /home/agent (sandcastle overrides per-run anyway)
- ENTRYPOINT ["sleep", "infinity"] keeps the container alive
2. **"Not logged in · Please run /login"** inside the container —
Claude Code on macOS stores credentials in the Keychain, NOT in
~/.claude/.credentials.json. Sandcastle's bind-mount of ~/.claude
finds nothing usable. Documented the workaround:
- README.md "Sandcastle setup (one-time)" — macOS-specific
block with the `security find-generic-password ... > ~/.claude/.credentials.json`
one-liner + chmod 600 + the security trade-off (plaintext
file vs keychain isolation)
- docs/guides/runbook.md "Using Sandcastle → Prerequisites" —
step 3 (Authentication) gets a "macOS quirk" subsection with
the same extraction one-liner + the API-key fallback as the
alternative path
- scripts/work/{dispatch,decompose}.mjs — when the sandcastle
error matches /Not logged in|Please run \/login/ AND we're on
darwin, the dispatcher prints the keychain-extraction
commands + the API-key fallback inline above the generic
"See runbook" line, so future agents discover the fix at the
failure site
The image rebuilds clean (`pnpm exec sandcastle docker
build-image`) at ~1.95GB and the container survives sandcastle's
exec — confirmed by reaching the "Not logged in" stage (which is
the next-layer issue, not the Dockerfile issue).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
