Building a Feature End-to-End

Walk a feature from idea to running code: plan, edit files, run the dev server, verify.

Claude Code is at its best when it takes a feature all the way from idea to working code.

A typical flow

  1. Describe the feature — "add a newsletter signup that posts to /api/subscribe".
  2. Let Claude plan — it identifies which files to create or edit.
  3. Review the edits — Claude writes the HTML, CSS, and JS across files.
  4. Run it — Claude can start your dev server and open the page.
  5. Verify — check the behavior, then ask for fixes if needed.

Keep it iterative

Ship the feature in small pieces. Get the form rendering first, then wire up submission, then add validation. Each step is easy to check.

Example

Example · bash
# A single end-to-end task for Claude Code:
#   "Add a newsletter signup form to the footer. On submit, POST the email
#    as JSON to /api/subscribe, show a success message on 200 and an error
#    message otherwise. Then start the dev server and confirm it works."

# Claude Code will:
#   1. Edit the footer markup and add the form
#   2. Add the fetch() submission logic
#   3. Run `npm run dev` and check the page
#   4. Report back with the diff and result

When to use it

  • Build a user-profile edit form end-to-end: Claude Code creates the component, the API route, and the validation schema.
  • Add a Stripe webhook handler by describing the event types and the database updates that should follow.
  • Implement infinite scroll on a product list — Claude Code adds the Intersection Observer, the fetch logic, and the state.

More examples

Plan the feature before writing code

Asking Claude Code to plan first catches missing steps before files are touched.

Example · bash
claude "Before writing any code, list every file you will create or edit to add a user-avatar upload feature that stores images in S3."

Build and verify in one session

Tells Claude Code to run the dev server after writing the code so it can verify the route is reachable.

Example · bash
claude "Add a POST /api/contact route in src/app/api/contact/route.ts that:
- Reads name, email, message from the request body
- Validates all three fields are non-empty
- Sends an email via Resend SDK
- Returns {ok:true} or a 400 error
Then run the dev server and confirm the route responds."

Iterate after reviewing output

Shows the iterative loop: review what Claude Code built, then refine with a targeted follow-up task.

Example · bash
# After reviewing the generated code:
claude "The contact form works but it doesn't show a success message after submit. Add a toast notification using the existing <Toast> component in src/components/Toast.tsx"

Related

claude cc tasksclaude cc git

Discussion

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