Nemo Gym Docs

NeMo Gym Docs Maintenance

Unified skill for adding, updating, moving, and removing pages on the NeMo Gym Fern documentation site.

Scope Rule

ALL docs edits happen under fern/. All new pages — including release notes and migration guides — belong under fern/.

Bleeding-edge tree + GA snapshots. Gym keeps one bleeding-edge content tree at fern/versions/latest/ (the folder name is historical — it's mounted under the main slug via main.yml) and one frozen GA snapshot per shipped release (currently fern/versions/v0.2.1/). All new edits land in fern/versions/latest/. The latest.yml file is a GA alias — a symlink to the current GA's yml — so /latest/... and /<current-ga>/... serve the same pages. Back-ports into a frozen GA snapshot are deliberate and rare; default to editing fern/versions/latest/ only.

Layout at a Glance

fern/
├── fern.config.json          # Org + Fern CLI version (currently 4.80.3)
├── package.json              # `npm run dev|check|generate` — wraps `npx -y fern-api@latest`
├── docs.yml                  # Site config: instances, versions, tabs, redirects, libraries
├── versions/
│   ├── latest.yml            # GA alias — symlink to the current GA's yml (currently v0.2.1.yml)
│   ├── main.yml              # Nav tree for the bleeding-edge train (mounts ./latest/pages)
│   ├── latest/pages/         # MDX content for the bleeding-edge train (slug: main)
│   ├── v0.2.1.yml            # Nav tree for the 0.2.1 GA snapshot
│   └── v0.2.1/pages/         # MDX content for the 0.2.1 GA snapshot
├── components/               # Custom TSX (CTAButtons, NavButton, CustomFooter)
├── assets/                   # Images, SVGs, favicon
├── main.css                  # Global theme overrides (NVIDIA green, badge spacing, etc.)
└── product-docs/             # GENERATED library reference (gitignored)

File system                                            Published URL
─────────────────────────────────────────────────────  ──────────────────────────────────
fern/versions/latest/pages/get-started/quickstart.mdx  docs.nvidia.com/nemo/gym/main/get-started/quickstart
fern/versions/v0.2.1/pages/get-started/quickstart.mdx  docs.nvidia.com/nemo/gym/v0.2.1/get-started/quickstart
                                                       docs.nvidia.com/nemo/gym/latest/get-started/quickstart  (GA alias)

Operations

Add a Page

1. Gather: page title, target section, filename (kebab-case .mdx), subdirectory under fern/versions/latest/pages/.

2. Create fern/versions/latest/pages/<subdirectory>/<filename>.mdx:

   ---
   title: "<Page Title>"
   description: "One-line SEO description (or empty string)"
   position: 3
   ---
   
   # <Page Title>
   
   <content>
   

3. If the parent folder is mounted in main.yml with title-source: frontmatter, the page is auto-discovered — no nav edit needed. Otherwise add a - page: entry under the right section: in fern/versions/main.yml.

4. Do not mirror into the current GA snapshot folder (e.g., v0.2.1/) — frozen GA snapshots only get back-ports on explicit request.

Update a Page

1. Locate by path, title, or keyword (grep -rn in fern/versions/latest/pages/).
2. Content only — edit the MDX in fern/versions/latest/pages/. Don't touch v0.2.1/ unless this is an explicit back-port.
3. Title change — update the frontmatter title: and (if the parent uses title-source: frontmatter) nothing else; otherwise update the nav - page: entry too.
4. Section move — git mv the file, update its path: in main.yml, fix all incoming links inside fern/versions/latest/pages/.
5. Slug change — folders use the page filename for the slug. Renaming the file changes the URL; add a redirect in fern/docs.yml so the old URL keeps working.

Remove a Page

1. Find incoming links: grep -rn "<filename>" fern/versions/latest/pages --include="*.mdx".
2. git rm the file from fern/versions/latest/pages/.
3. Remove the matching - page: block from main.yml if it was a manual entry.
4. Fix or remove all incoming links.
5. Add a redirect in fern/docs.yml if the URL was public.

Back-port to a GA Snapshot

Only back-port when the user explicitly asks ("back-port to v0.2.1"). Apply the same change inside the GA snapshot's pages/ folder (e.g., fern/versions/v0.2.1/pages/) and update its yml if needed. latest.yml is a symlink to the current GA's yml, so nav changes propagate automatically.

Worked Example: Adding a Page

Request: "Add a how-to for collecting rollouts under Get Started."

1. Create fern/versions/latest/pages/get-started/rollout-collection.mdx:

   ---
   title: "Collect Rollouts"
   description: "Run the agent against your dataset and write results to JSONL"
   position: 4
   ---
   
   # Collect Rollouts
   
   <content>
   

2. The get-started folder in main.yml uses title-source: frontmatter, so the page appears automatically. position: 4 controls ordering — it's optional; without it, pages sort alphabetically by filename.

3. cd fern && npm run check && npm run dev, verify /main/get-started/rollout-collection renders.

Worked Example: Renaming a Slug (with Redirect)

Request: "Rename /main/get-started/setup to /main/get-started/detailed-setup."

1. git mv fern/versions/latest/pages/get-started/setup.mdx fern/versions/latest/pages/get-started/detailed-setup.mdx.

2. Add a redirect in fern/docs.yml:

   redirects:
     - source: "/main/get-started/setup"
       destination: "/main/get-started/detailed-setup"
   

3. grep -rn "/get-started/setup" fern/versions/latest/ and update any incoming links.

Content Guidelines

NeMo Gym uses Fern-native MDX components directly. Do not use GitHub > [!NOTE] syntax — it will not render.

Images live in fern/assets/ (shared) or under a version's pages/ (version-scoped). Reference with root-relative paths.

Cards and Badges

Index pages use a <Cards> grid. Each <Card> can carry one or more <Badge> tags to indicate scope, status, or read-time.

Valid intents: success, note, tip, warning, error, info, launch, check. Use <Badge minimal outlined>...</Badge> (no intent) for neutral tags.

Place badges as the last line inside the <Card>, separated by a blank line from the body text. The CSS in main.css (.fern-card .fern-docs-badge) handles spacing — do not add inline style= props.

<Cards>
  <Card title="Quickstart" href="/main/get-started/quickstart">
    Install, start servers, and collect your first rollouts in one page.

    <Badge intent="success" minimal outlined>start here</Badge> <Badge minimal outlined>5 min</Badge>
  </Card>
</Cards>

Frontmatter Fields

---
title: "<Page Title>"        # required — used for nav and <h1>
description: ""              # required (may be empty string) — SEO
position: 1                  # optional — orders auto-discovered pages within a folder
---

The MDX body should still open with # <Page Title> matching the frontmatter title. Folders using title-source: frontmatter in the version YAML pull the nav label from title:.

Validate

First-time setup: authenticate the CLI against the nvidia Fern org via Google SSO (one-time, browser flow):

npx -y fern-api@latest login    # opens browser → sign in with your @nvidia.com Google account

Run from fern/ (no install step — scripts shell out to npx -y fern-api@latest):

npm run check       # `fern check` — YAML + frontmatter validation
npm run dev         # `fern docs dev` — localhost:3000 hot-reload preview

fern check must pass before commit. The dev server's broken-link warnings for cross-version links like /latest/about are false positives — Fern's local validator does not resolve the version slug from docs.yml against latest.yml. The published site renders them correctly.

To regenerate the autodoc library reference (gitignored under product-docs/):

npm run generate:library    # `fern docs md generate`

Commit & Preview

git add fern/
git commit -s -m "docs: <add|update|remove> <page-title>"

PRs that touch fern/** get an automatic Fern preview URL posted as a comment by .github/workflows/fern-docs-preview-comment.yml. No manual step needed.

                    ┌─ fern-docs-ci.yml                  → fern check
PR (touches fern/) ─┼─ fern-docs-preview-build.yml       → upload fern/ artifact (no secrets)
                    └─ fern-docs-preview-comment.yml     → 🌿 preview URL comment

Push to main (touches fern/**)          → publish-fern-docs.yml → docs.nvidia.com/nemo/gym
Tag push (docs/v*)                        → publish-fern-docs.yml → docs.nvidia.com/nemo/gym
Manual dispatch                           → publish-fern-docs.yml → docs.nvidia.com/nemo/gym

The preview-comment + publish jobs require the DOCS_FERN_TOKEN repository or organization secret (from fern token).

Publishing to Production

Production publishes on three triggers (see .github/workflows/publish-fern-docs.yml):

1. Push to main when fern/** changes — continuous staging.
2. Tag push matching docs/v* — versioned release.
3. Manual dispatch from the Actions tab.

Tag format must be docs/v<MAJOR>.<MINOR>.<PATCH>. Do not push a tag unless the user asks.

git tag docs/v0.3.0
git push origin docs/v0.3.0

URL → version mapping:

docs.nvidia.com/nemo/gym/latest/...   → GA alias (currently mirrors v0.2.1)
docs.nvidia.com/nemo/gym/main/...     → bleeding-edge train (folder: ./latest/pages)
docs.nvidia.com/nemo/gym/v0.2.1/...   → 0.2.1 GA snapshot

Cutting a New Version Train

When the user ships a new version (e.g. v0.3.0):

1. cp -r fern/versions/latest fern/versions/v0.3.0 — frozen snapshot of the bleeding-edge folder.
2. cp fern/versions/main.yml fern/versions/v0.3.0.yml and rewrite ./latest/ path prefixes to ./v0.3.0/.
3. Retarget the fern/versions/latest.yml symlink at the new GA's yml: cd fern/versions && ln -sfn v0.3.0.yml latest.yml.
4. In fern/docs.yml versions:, add the new GA snapshot entry (display-name: "0.3.0", slug: v0.3.0, availability: stable) and demote/remove the previous GA snapshot per the support policy.
5. fern/versions/latest/pages/ keeps moving forward as the bleeding-edge tree. main.yml is unchanged.
6. Tag docs/v0.3.0 and push to publish.

Debugging

Key References