feat(cca): Neon Postgres

[Tobbe]

Optionally give the user a Neon database as part of creating a Cedar app

[netlify]

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[nx-cloud]

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☁️ Nx Cloud last updated this comment at 2026-04-02 07:52:10 UTC

[greptile-apps]

Greptile Summary

This PR adds an optional Neon Postgres database to create-cedar-app via a new --db neon-postgres flag (requires --esm). The previous blocking issues — missing ESM guard, broken path resolution, silent {{DATABASE_URL}} placeholder, and invalid CLI validation — are all resolved in this revision.

Confidence Score: 5/5

• Safe to merge; all previously blocking issues are resolved and only minor P2 suggestions remain.
• All P0/P1 concerns from prior review rounds are addressed: the CLI validation now correctly accepts neon-postgres, the ESM guard is in place, the fetch error path now throws on non-2xx responses, and the broken prismaVersion() path is replaced with a hardcoded constant. The two remaining findings are P2 style suggestions (hardcoded ref and pinned version without caret).
• No files require special attention.

Important Files Changed

Filename	Overview
packages/create-cedar-app/src/project-files.ts	Core logic for neon-postgres overlay: fetches a Neon DB, writes connection string into .env.defaults via placeholder replacement; error path leaves DATABASE_URL empty (user is warned); ref is hardcoded to 'cedarjs'.
packages/create-cedar-app/src/handle-args.ts	Adds handleDatabasePreference() with validation and ESM guard for neon-postgres; addresses the previously flagged missing ESM guard.
packages/create-cedar-app/database-overlays/neon-postgres/api/src/lib/db.ts	New db.ts using PrismaPg adapter; guards against missing DATABASE_URL at startup and re-exports from the generated client.
packages/create-cedar-app/database-overlays/pglite/api/package.json	Switches @prisma/adapter-pg from hardcoded ^7.5.0 to the {{PRISMA_VERSION}} placeholder, which resolves to 7.6.0 (no caret) at scaffolding time — removing patch-version flexibility for new pglite projects.

_{Reviews (5): Last reviewed commit: "improve messaging and error handling" | Re-trigger Greptile}

[github-actions]

The changes in this PR are now available on npm.

Try them out by running yarn cedar upgrade -t 4.0.0-canary.13719

Or try it in a new app with yarn dlx create-cedar-app@4.0.0-canary.13719