Ask Codex to give your contact form a working backend.

Codex is OpenAI's coding agent, available across the Codex app, CLI, IDE extension, and cloud workflows. It can inspect and change a repository and run its checks. It is not a hosting platform, and this guide is about the current agent, not the older model family that used the Codex name.

1. 1
   Create your Form Plume accountStart free and give your Codex form a hosted endpoint for email, submissions, spam filtering, uploads, integrations, and webhooks.Start free
2. 2
   Create the form and copy the endpointCopy the endpoint URL from Form Plume. It looks like https://api.formplume.com/f/your-slug
3. 3
   Connect it inside CodexInspect the diff and check output, then test success and failure from the built application before deployment. Send one test submission from the real Codex app or preview environment and confirm it reaches Form Plume.

Give Codex the outcome and constraints

In this repository, connect the existing contact form to Form Plume.
Public endpoint: https://api.formplume.com/f/your-public-slug
 
First read AGENTS.md and inspect the framework, package scripts, and current form.
Preserve its design, fields, validation, and accessibility. Prefer a native POST when
navigation fits; otherwise send FormData with the established client pattern. For fetch,
add inline pending, success, and non-2xx error behavior without clearing values on failure.
For native POST, verify the hosted success and error navigation.
Do not add a server route, database, or dependency only for delivery. The form slug is
public, but access keys, webhook signing secrets, provider keys, and server-only env
values must never enter browser code. Run the relevant formatter, typecheck, tests,
and production build. Review your own diff for scope creep and report changed files,
commands, results, and any residual risk. Do not commit or deploy.

AGENTS.md is the durable place for repository-specific conventions. The prompt supplies the one-off endpoint and task boundary. This combination helps Codex discover the correct framework instead of dropping a generic component into the wrong directory.

Work locally or in cloud deliberately

The app, CLI, and IDE extension can work against local repository context. Codex cloud uses a configured remote environment. Whichever surface you choose, make the expected verification commands available and review the resulting Git diff. A cloud task may not reproduce a browser-only integration or production allowed-domain rule, so the final submission check still belongs on the deployed site.

git diff --check
git diff --stat
pnpm test
pnpm build

These are illustrative. Codex should read the repository and run the actual commands it defines. Do not accept a generic "tests pass" summary without the command and result.

Keep the public boundary clear

https://api.formplume.com/f/your-public-slug is designed to appear in form HTML and browser requests. Protected-form access keys and webhook signing secrets are authorization material and must remain in a server-side secret store. A client environment variable remains public after bundling.

Verify the actual edit

1. Confirm Codex found the real form and changed only the necessary files.
2. Check every submitted field has a name and the request uses FormData correctly.
3. Run the repository's exact format, type, test, and build commands.
4. Submit valid data and verify storage and notification in Form Plume.
5. Temporarily break the slug. For fetch, verify the inline error is announced and values remain. For native POST, verify the hosted error navigation.
6. Restore it and repeat from the production origin.

Continue with the framework Codex discovers, such as React, Astro, or HTML. You can compare the workflow with Cursor, Claude Code, and Windsurf.

Primary sources

• OpenAI Codex documentation
• Codex glossary