Build one secure full-stack interaction
https://patrickz.ai/learn/full-stack-vertical-slice/

OUTCOME
Design and test one create-and-list flow with a server-side user boundary.

YOU NEED
A coding agent and comfort with a local client/server project. Use fictional data and two test accounts.

1. Define the practice version
The archived LifeTracker project explored separate frontend, API and infrastructure layers. Use the lesson as architecture practice; verify current identity-provider guidance instead of copying older service choices.

2. Build step 1
Build one vertical slice: create and list habits.

3. Build step 2
Define the API contract before wiring the interface.

4. Build step 3
Add authentication and verify tokens on the server.

5. Build step 4
Store user IDs with every record.

6. Build step 5
Add tests for cross-user access.

7. Build step 6
Add infrastructure automation after the local system works.

8. Run the experiment
Create one record as user A. Confirm user B cannot list, fetch or modify it through direct API calls as well as the interface. Test an unauthenticated request.

PROMPT
Work in a disposable practice project. Explain any setup requirements before changing files. Build one small step at a time and show how I can check it.

Design a secure vertical slice for a habit tracker with React and Express. Include TypeScript request/response schemas, authentication boundary, database fields, validation, error cases, and tests proving one user cannot read another user’s habits.

Compare this older frontend/backend/Kubernetes architecture with a modern managed-platform alternative. Preserve security and portability, but identify complexity that is unnecessary for an early prototype.

My first-version boundary: The archived LifeTracker project explored separate frontend, API and infrastructure layers. Use the lesson as architecture practice; verify current identity-provider guidance instead of copying older service choices.

EXAMPLE / EXPERIMENT
Create one record as user A. Confirm user B cannot list, fetch or modify it through direct API calls as well as the interface. Test an unauthenticated request.

CHECK YOUR RESULT
[ ] The server verifies identity and ownership.
[ ] Cross-user access is rejected.
[ ] Validation errors are visible and do not expose secrets.

IF IT FAILS
Hiding a button is not authorization. Enforce the boundary on the server, and choose current supported identity services before production.

MY RESULT / NEXT CHANGE