chore: support docs only builds

[sarahxsanders]

Changes

I am proposing to add a GATSBY_DOCS_ONLY build mode to speed up preview deploys for docs PRs

the problem: every PR builds the entire site, even with GATSBY_MINIMAL=true. for PRs that only touch docs, slow builds are one contributing factor to stale agent-generated docs PRs not getting merged (one factor among many that I am addressing this quarter!)

this change:

• CI workflow changes to detect whether a PR only touches docs by looking for PRs with changes to ONLY contents/docs AND src/navs/index.js for sidebar nav, vercel.json for redirects

please opine if you feel strongly about any of these files being included, i'm on the fence about vercel.json because our Inkeep agent isn't allowed to touch that

• doesn't affect PRs that touch more than docs

Testing

i tested locally:

• cold docs only build: 376s
• docs-only build w/ cache: 164s
• previous minimal build: 15 min

CI should improve further over the local numbers

to test locally:

NODE_OPTIONS='--max_old_space_size=8192' GATSBY_DOCS_ONLY=true pnpm build

[github-actions]

Deploy preview

Status	Details	Updated (UTC)
🟢 Ready	View preview	Apr 10, 2026 07:17PM