Reproduce an issue (sandboxed)

Reproduce an nx bug entirely inside an isolated container and report the outcome. The untrusted repro — its install (arbitrary postinstall scripts) and its repro command — runs only in the sandbox, never on the host. --rm destroys everything on exit; nothing touches the host filesystem.

This is the one reproduction engine in the repo. It has two front doors:

Entry A — a GitHub issue (human: /reproduce-issue <N>)

1. Fetch the issue:

   gh issue view <N> --repo nrwl/nx --json number,title,body,comments,labels

2. Extract from the body: the repro repo URL (or create-nx-workspace steps), the exact command(s) that show the bug, the reported vs expected behavior, and the Nx Report (nx version + Node version).
3. Fill the parameters below and run the sandbox (default nx-version = whatever the issue reports / the repo pins; default registry = public npm).

Entry B — explicit parameters (agent: reproduce-verifier Level 2)

The caller passes these directly:

• repro — repo:<git-url> (clone a public repo) OR create:"<create-nx-workspace args>".
• nx-version:<version> — install this published nx and rewrite the repro's nx / @nx/* / @nrwl/* deps to it. For reproducing against a released version.
• nx-build:<git-ref> (PR-verification mode) — instead of a published version, build nx from this nrwl/nx commit inside the sandbox and reproduce against it. Uses the nx-review-sandbox image; the skill derives the version and serves it from a localhost verdaccio in the same container. Mutually exclusive with nx-version.
• nx-registry:<url> (optional, nx-version mode only) — registry to install from. Default public npm.
• command:"<repro-cmd>" — the command whose output/exit code decides the verdict.
• node-image:<img> (optional) — base image matching the issue's Node (default node:22; public images are multi-arch → native on Apple Silicon).
• expect:<reported symptom> (optional), setup:"<files/steps>" (optional) — files to create in the workspace first.

Platform (where the sandbox boundary comes from)

Run uname -s once:

• Linux → add --runtime=runsc to docker run (gVisor is the sandbox).
• macOS (Darwin) → omit --runtime=runsc (the Docker VM is the sandbox). Verify docker info works; if not, tell the user to colima start (or start Docker Desktop / OrbStack).

The command below shows the Linux form — on macOS drop --runtime=runsc, keep the rest.

Preflight — check the environment, fail with a FIX (not a mystery)

Before running anything, verify prerequisites in order and stop at the first miss, printing the one-line fix. Most misses point at the setup-review-sandbox skill, which installs/builds everything.

1. Docker is up:

   docker info >/dev/null 2>&1 && echo up || echo MISSING

   Miss → Linux: sudo systemctl start docker. macOS: colima start (or open Docker Desktop). Or run setup-review-sandbox.

2. Container networking works (the check that would have caught the veth breakage):

   docker run --rm --network none alpine true   # A: is the sandbox itself OK?
   docker run --rm alpine true                  # B: is networking OK?

   If A passes but B fails with veth ... operation not supported → networking is broken (usually a kernel update left veth unloadable). Fix: sudo modprobe veth; if that errors with a BTF/version mismatch, reboot (the running kernel no longer matches its modules).

3. Isolation runtime (platform-specific):

   • Linux — gVisor registered as a Docker runtime?

     docker info --format '{{range $k,$v := .Runtimes}}{{$k}} {{end}}' | grep -q runsc && echo ok || echo MISSING

     Miss → run setup-review-sandbox (installs + registers runsc).
   • macOS — the Docker VM (Colima / Docker Desktop) is the sandbox; step 1 already covered it. No runsc.

4. (PR-build mode ONLY) the toolchain image exists:

   docker image inspect nx-review-sandbox:latest >/dev/null 2>&1 && echo ok || echo MISSING

   Miss → run setup-review-sandbox (builds it from tools/review-sandbox/Dockerfile). Skip this check when reproducing against a published nx version — that path needs only steps 1–3 and a public node image.

If all needed checks pass, proceed.

Safety rails (do NOT break these)

• The untrusted repro runs only in the container. Never -v a host path in. nx comes from a registry (or docker cp-ed tarballs), never a mount.
• Always pass: --cap-drop ALL, --security-opt no-new-privileges, --memory 4g --cpus 4 --pids-limit 2048, --rm; plus --runtime=runsc on Linux.
• Network is ON (clone + install need it). gVisor still protects the host kernel; on macOS the VM protects the host.
• One docker command per Bash call. (Chaining inside the container's bash -c '...' is one host command, which is fine.)

Run

Detect platform, then a single host command does clone/create → dep-rewrite → install → repro, all inside the sandbox:

# RUNTIME="--runtime=runsc"   on Linux
# RUNTIME=""                   on macOS
docker run --rm $RUNTIME \
  --cap-drop ALL --security-opt no-new-privileges \
  --memory 4g --cpus 4 --pids-limit 2048 \
  node:22 bash -c '
    set -e
    git clone --depth 1 <GIT_URL> /repro          # repo: form
    # -- or -- npx --yes create-nx-workspace <ARGS> --directory /repro   # create: form
    cd /repro

    node -e '"'"'
      const fs=require("fs"),p=JSON.parse(fs.readFileSync("package.json","utf8")),v=process.argv[1];
      for (const s of ["dependencies","devDependencies"]) for (const n of Object.keys(p[s]||{}))
        if (n==="nx"||n.startsWith("@nx/")||n.startsWith("@nrwl/")) p[s][n]=v;
      fs.writeFileSync("package.json", JSON.stringify(p,null,2)+"\n");
    '"'"' <NX_VERSION>

    rm -f package-lock.json pnpm-lock.yaml yarn.lock
    PM=npm; test -f pnpm-workspace.yaml && PM=pnpm
    npm i -g pnpm@11 >/dev/null 2>&1 || true
    npm_config_registry=<NX_REGISTRY> $PM install

    ( timeout 300 <REPRO_COMMAND> ); echo "REPRO_EXIT=$?"
    echo "kernel: $(uname -r)"
  '

Substitute <GIT_URL>/<ARGS>, <NX_VERSION>, <NX_REGISTRY> (default https://registry.npmjs.org), and <REPRO_COMMAND>.

Classify + report

Compare output and REPRO_EXIT against the reported symptom, and return this block (verdicts match the reproduce-verifier's Level 2 vocabulary):

repro:        <repo-url | create-nx-workspace ...>
nx-version:   <version>   (registry: <url>)
command:      <verbatim>
exit code:    <N>
verdict:      <PR_REPRO_PASSES | PR_REPRO_FAILS | PR_REPRO_FAILS_DIFFERENT | PR_REPRO_INCONCLUSIVE | SETUP_FAILED>
output (tail ~20 lines):
  <...>

• succeeded (matches the claimed fix) → PR_REPRO_PASSES
• failed with the reported error → PR_REPRO_FAILS
• failed with a different error → PR_REPRO_FAILS_DIFFERENT (flag for human)
• unclear → PR_REPRO_INCONCLUSIVE
• clone/create/install broke before the repro ran → SETUP_FAILED (say which step + tail)

(For a human /reproduce-issue run against a released version, "reproduced" vs "did not reproduce" is the plain-language answer; the verdict vocab above is for the agent.)

PR-build mode — build nx from source in the sandbox (nx-build)

When nx-build:<git-ref> is given, do everything in one nx-review-sandbox container (it carries the mise toolchain incl. java + dotnet, required by nx's @nx/dotnet/@nx/gradle graph plugins). One container, localhost throughout — no host build, no host verdaccio, no host.docker.internal, no listen-address change:

# RUNTIME="--runtime=runsc"  on Linux, ""  on macOS
docker run --rm $RUNTIME \
  --cap-drop ALL --security-opt no-new-privileges \
  --memory 20g --cpus 6 --pids-limit 8192 --tmpfs /work:rw,exec,size=16g \
  -e CI=true -e NX_DAEMON=false \
  nx-review-sandbox:latest bash -c '
    set -e
    # 1. build nx from the PR commit
    cd /work
    git clone --filter=blob:none https://github.com/nrwl/nx nx && cd nx
    git checkout <GIT_REF>
    mise install && pnpm install --frozen-lockfile
    PORT=4873
    pnpm nx local-registry @nx/nx-source --port=$PORT >/tmp/verdaccio.log 2>&1 &
    for i in $(seq 1 60); do curl -sf http://localhost:$PORT/-/ping >/dev/null 2>&1 && break; sleep 1; done
    NX_LOCAL_REGISTRY_PORT=$PORT pnpm nx populate-local-registry-storage @nx/nx-source
    NXV=$(node -p "require(\"/work/nx/dist/packages/nx/package.json\").version")

    # 2. reproduce against that build — same container, localhost registry
    cd /work
    git clone --depth 1 <GIT_URL> repro     # or: npx --yes create-nx-workspace <ARGS> --directory repro
    cd repro
    # rewrite nx/@nx/@nrwl deps to "$NXV" (same node one-liner as the Run section)
    rm -f package-lock.json pnpm-lock.yaml yarn.lock
    npm_config_registry=http://localhost:$PORT pnpm install
    ( timeout 300 <REPRO_COMMAND> ); echo "REPRO_EXIT=$?"
    echo "kernel: $(uname -r)"
  '

Because verdaccio and the repro live in the same container, the registry is plain localhost — the reachability/listen-address problems a host verdaccio would create simply don't exist. Classify the result exactly as in "Classify + report".

Prerequisite: the nx-review-sandbox image (setup-review-sandbox). The nx build is heavy (~several min + several GB) — RAM-backed via the tmpfs above so it stays off the host disk.

Cleanup

--rm destroys the container and everything in it on exit. Nothing persists on the host. Stray sandbox containers/images: /sandbox-prune.