GitNexus/.devcontainer

GitNexus Devcontainer

A cross-platform Dev Container that pre-installs Claude Code, OpenAI Codex CLI, and Cursor CLI alongside the GitNexus native build chain. Designed for Windows 11 (Docker Desktop + WSL2 backend) as the primary host with first-class support for macOS and Linux.

Quick start

1. Install Docker Desktop (Windows/macOS) or Docker Engine (Linux).
2. Install VS Code with the Dev Containers extension.
3. Open the repo in VS Code → Command Palette → Dev Containers: Reopen in Container.
4. Wait for the first build (~3–6 minutes) and postCreateCommand to finish installing workspace dependencies.
5. Authenticate the three CLIs once — see First-time CLI authentication below.

Windows 11 (primary host) — WSL2 setup

Clone the repo inside WSL2, not on the Windows side. Bind-mounting a Windows-side path (C:\…) through Docker Desktop's WSL2 backend works but suffers from poor IO and unreliable file watchers (Vite/jest --watch will miss changes). The fix is to clone into the WSL2 filesystem.

# 1. Install WSL2 and a Linux distro if you haven't already.
wsl --install -d Ubuntu

# 2. Enter WSL.
wsl

# 3. Clone the repo inside your WSL2 home directory.
cd ~
git clone https://github.com/abhigyanpatwari/GitNexus.git
cd GitNexus

# 4. Launch VS Code from inside WSL — this opens VS Code attached to the WSL2
#    filesystem, so subsequent "Reopen in Container" uses the WSL2-side path.
code .

Then run Dev Containers: Reopen in Container. The workspace will be bind-mounted from \\wsl$\Ubuntu\home\<user>\GitNexus, which is fast and gives reliable file-system events.

Make sure Docker Desktop's WSL integration is enabled for your distro: Docker Desktop → Settings → Resources → WSL Integration → toggle on the distro you cloned into.

macOS

Open the repo folder in VS Code → Reopen in Container. The image is multi-arch; on Apple Silicon you'll pull the linux/arm64 variant automatically.

Linux

Same as macOS — open in VS Code and reopen in container. updateRemoteUserUID: true (default) shifts the container's node user UID/GID to match your host user, so bind-mounted files stay writable without extra setup.

First-time CLI authentication

Interactive login is the default for all three CLIs. Credentials persist in per-workspace named volumes scoped by ${devcontainerId}, so you authenticate once per project — subsequent rebuilds reuse the stored credentials.

Claude Code

claude login

Opens a browser auth flow. VS Code's port forwarding handles the OAuth callback automatically. After auth, ~/.claude/ is populated in the named volume and persists across rebuilds. The DISABLE_AUTOUPDATER=1 env var prevents the running CLI from updating itself — rebuild the container to pick up a newer Claude Code.

OpenAI Codex CLI

codex login --device-auth

The device-code flow prints a URL and a one-time code. Visit the URL on your host browser, paste the code, and the CLI authenticates without needing a callback listener — this is the most reliable path inside containers. Credentials persist in ~/.codex/auth.json inside the named volume.

codex login (browser-callback variant) also works but can be flaky in some headless contexts; prefer --device-auth.

Cursor CLI

cursor-agent login

Opens a browser auth flow; VS Code's port forwarding handles the callback. After auth, credentials persist in ~/.cursor/cli-config.json inside the named volume.

Verify any time with cursor-agent status.

Alternative: API key authentication (CI / headless)

For non-interactive use (CI runners, automated scripts), all three CLIs accept API keys via env vars:

CLI	Env var	Where to get the key
Claude Code	ANTHROPIC_API_KEY	https://console.anthropic.com/settings/keys
Codex	OPENAI_API_KEY	https://platform.openai.com/api-keys
Cursor	CURSOR_API_KEY	Cursor dashboard → Integrations

These env vars are intentionally not injected into the container from the host. ${localEnv:VAR} resolves an unset host variable to an empty string, and some CLIs (Cursor in particular) treat a set-but-empty key as "use this key" rather than "fall back to stored login" — which would silently break the login flow for everyone who hasn't pre-set the host var.

To use an API key inside the container, export it in your terminal session:

export ANTHROPIC_API_KEY=sk-ant-...
# or OPENAI_API_KEY, or CURSOR_API_KEY

For persistence across container shells, carry the export via your VS Code dotfiles repository. VS Code clones the dotfiles repo into the container on attach and runs your install command, so the export lands in ~/.bashrc / ~/.zshrc per your own setup — and your API keys stay out of this repo's committed devcontainer.json.

A non-empty API key env var takes precedence over stored login credentials for each CLI.

Port forwarding

Port	Service	Notes
5173	Vite dev server (gitnexus-web)	Auto-forwarded with notification
4747	gitnexus serve HTTP API	Must not be remapped — gitnexus-web hardcodes http://localhost:4747 as the default backend URL
4173	Static web (Vite preview)	Silently forwarded

VS Code's Ports panel shows forwarded ports once their listener starts.

Known gotchas

• LadybugDB integration tests may fail in containers (file-locking, AGENTS.md § Testing). Default to npm run test:unit inside the container; run integration tests on the host. Tracking issue: documented as a known limitation.
• Single-writer LadybugDB constraint (GUARDRAILS.md § LadybugDB lock). Don't run gitnexus analyze on the host and inside the container against the same .gitnexus/ directory simultaneously — the second writer will get database busy.
• Native grammar builds add ~30s to first install. Tree-sitter Dart/Proto/Swift grammars build during gitnexus's postinstall. To skip them (loses parsing for those three languages), set GITNEXUS_SKIP_OPTIONAL_GRAMMARS=1 in your shell or add it to remoteEnv and rebuild.
• tree-sitter-kotlin warnings on install are expected (per AGENTS.md). Ignore them.
• .mcp.json works inside the container: npx -y gitnexus@latest mcp resolves cleanly because npm registry is reachable and the workspace bind mount exposes the same .mcp.json the host sees.
• Husky pre-commit fires inside the container without extra setup. The root npm install (run automatically in postCreateCommand) installs the hook via package.json prepare.

Rebuild / reset

• Rebuild Container (Command Palette) — re-runs the Dockerfile build and postCreateCommand against the existing named volumes (auth + history persist).
• Rebuild Container Without Cache — fresh image layers, same volumes.
• To clear a stale named volume (e.g., force a re-login):

  docker volume ls | grep gitnexus   # find the per-devcontainer volume
  docker volume rm <volume-name>
  

  Then rebuild.

Bumping CLI versions

Three build args control pinned versions:

• CLAUDE_CODE_VERSION — informational. Anthropic's official Feature (ghcr.io/anthropics/devcontainer-features/claude-code:1) installs the latest stable at build time; rebuild to pick up a newer Claude Code. DISABLE_AUTOUPDATER=1 keeps it locked between rebuilds.
• CODEX_VERSION — pinned in .devcontainer/devcontainer.json build.args and consumed by npm install -g @openai/codex@${CODEX_VERSION}. Bump the value and rebuild.
• CURSOR_VERSION — informational only. The Cursor installer (cursor.com/install) does not expose version pinning; it always pulls latest at build time. To bump, rebuild the container; auto-update inside the running container is suppressed by not invoking cursor-agent update.

What's not included (yet)

• Egress firewall. The original plan included an opt-in iptables/ipset firewall adapted from Anthropic's reference devcontainer. It was deferred to a follow-up PR — runArgs is static in devcontainer.json, so toggling NET_ADMIN/NET_RAW capabilities cleanly requires either a separate devcontainer-firewall.json profile or an initializeCommand-generated overlay. Track at the project's issue tracker if you need this.
• Codespaces tuning. The current config works in Codespaces incidentally (no privileged capabilities, no host-mount assumptions), but isn't actively tested there.
• Playwright e2e support. gitnexus-web's npm run test:e2e needs Chromium libs that the base image doesn't ship. Use the host for e2e until a Playwright layer is added.

Troubleshooting

Symptom	Likely cause	Fix
EACCES on first claude login / codex login / cursor-agent login	Named volume mount got a stale state	docker volume rm the relevant *-config-<devcontainerId> volume and rebuild
EPERM: operation not permitted, copyfile ... '.husky/_/h' in postCreateCommand	Leftover .husky/_/ from a previous container run; Docker Desktop's Windows bind mount won't let the new container's node user overwrite it. postCreateCommand already runs rm -rf .husky/_ defensively, but if you hit it on an older config, delete .husky/_/ on the host (rm -rf .husky/_) and rebuild	Long-term: clone the repo inside WSL2 (see Windows 11 WSL2 setup) — WSL-side filesystems don't have this bind-mount class of issue
Vite never hot-reloads on Windows	Repo cloned on Windows side, not WSL2	Re-clone inside WSL2 (see WSL2 setup)
gitnexus-web can't reach the backend	4747 was remapped or backend isn't running	Verify the Ports panel shows 4747 forwarded with no remap; start the backend with cd gitnexus && npx gitnexus serve
npm install fails on tree-sitter-swift / proto / dart	Native build toolchain missing	This shouldn't happen in the devcontainer — verify the apt layer installed python3 make g++. If iterating, set GITNEXUS_SKIP_OPTIONAL_GRAMMARS=1 to skip the vendored grammars
Integration tests fail with database busy	LadybugDB single-writer constraint	Don't run host-side gitnexus analyze while the container is also analyzing the same repo; choose one writer
API key env vars not visible inside the container	They are intentionally not auto-propagated from the host (so an empty/stale host var can't silently break *-login for everyone else)	export ANTHROPIC_API_KEY=... / OPENAI_API_KEY=... / CURSOR_API_KEY=... inside the container shell, or carry it via your VS Code dotfiles repo for persistence