Build failure — handover note

Summary

Next.js 15 app on Railway. Build fails at the CSS step with Error: Cannot find module 'autoprefixer', imported from ./src/app/globals.css.

The repository was uploaded through GitHub's web drag-and-drop, so there is no package-lock.json and the person maintaining it has no terminal access.

Environment

Railway, Nixpacks builder, EU West

Repo is nested: Railway Root Directory is set to stakeholder-platform

Build command npm i then npm run build

Services: this app + Railway Postgres

What has been tried

Tailwind v4 originally. Failed with Cannot find native binding from @tailwindcss/oxide — the known npm optional-dependency bug (npm/cli#4828).

Added @tailwindcss/oxide-linux-x64-gnu explicitly. No change.

Downgraded to Tailwind v3 (pure JS, no native binary):

postcss.config.mjs → { plugins: { tailwindcss: {} } }

added tailwind.config.ts with the brand palette

globals.css → @tailwind base/components/utilities + CSS variables

package.json → tailwindcss@^3.4.17, postcss, autoprefixer

Moved tailwindcss, postcss, autoprefixer from devDependencies into dependencies, since Railway builds with NODE_ENV=production and skips dev dependencies.

The blocking symptom

npm i reports added 158 packages on every build, unchanged across the last three deploys, including after package.json was edited. Earlier it changed (103 → 158), so commits have reached the builder at least once.

158 is far too few for this dependency set — Next 15 + React 19 + Drizzle + Tailwind should be several hundred. This suggests the build is not using the package.json currently in the repository.

Decisive evidence (added after further testing)

Two facts together suggest the build is not seeing the repository files as GitHub displays them:

postcss.config.mjs was reduced to export default { plugins: {} }; and all @tailwind directives were removed from globals.css. The build still fails with Cannot find module 'autoprefixer', which should be impossible if Next were reading that config — with no plugins configured, nothing should be resolved at all. Next appears to be falling back to its default PostCSS configuration, i.e. it is not picking up the file.

npm i reports exactly added 158 packages on every build, unchanged across at least six deploys, several different package.json versions, and a Node 18 → Node 20 switch via NIXPACKS_NODE_VERSION. The Node change did take effect (visible in the Nixpacks header), so variables reach the build while file contents appear not to.

Commit SHAs do advance between deploys (d36d972f → 0ec2b575), so the service is not pinned to one commit.

Worth checking first

Is there a second PostCSS config (postcss.config.js alongside postcss.config.mjs)? Next may be preferring one over the other.

Does stakeholder-platform/package.json in the built commit actually contain tailwindcss / autoprefixer / postcss under dependencies?

Does clearing the Railway build cache change the added N packages figure?

Most likely causes, in order

A second package.json in the repo — one being edited, a different one being built. Worth checking for duplicates first.

Root Directory / build context mismatch — Railway resolving package.json from a different path than expected.

Stale build cache — the log mounts --mount=type=cache,target=/app/node_modules/.cache. Clearing the build cache and redeploying would rule this out.

What would settle it in one command

git clone && cd stakeholder-platform

npm install && npm run build

If it builds locally, the problem is Railway's build context, not the code. If it fails locally, the error will name the file directly.

Other context

The application code has never been compiled — it was written in an environment without npm registry access. Type errors are likely and next.config.ts currently sets typescript.ignoreBuildErrors: true as a temporary measure. That should be removed once the type errors are fixed.

The identity-resolution logic in src/lib/identity.ts is tested and passing — 13 unit tests, runnable with node --experimental-strip-types --test tests/identity.test.ts, no install required.

Once the build passes, remaining steps are: set the start command to npm run setup (creates tables and seeds), then revert it to npm run start, then generate a public domain. See docs/RAILWAY-DEPLOY.md.