Premier League Predictor: Astro — Chapter 12, Exercise 3
====================================================

TASK
Set PUBLIC_BASE_PATH=/predictor in a real .env file, update every
href/Astro.redirect()/fetch() call across Chapters 4-10 to use it,
mount the app behind nginx at /predictor/ exactly as shown, and
confirm every real user flow (creating a fixture, submitting a
prediction, viewing the league table, navigating between gameweeks)
works correctly through the mounted path — then unset the variable
and confirm the exact same codebase still works correctly at the
site root in dev mode with zero code changes.

SOLUTION

Steps to complete the hands-on part:

1. Add a real BASE_PATH constant (const BASE_PATH =
   import.meta.env.PUBLIC_BASE_PATH ?? '';) to every file that
   generates a path meant for the browser to follow:
   - src/pages/admin/seasons/[seasonId]/gameweeks/[gameweekNumber]/fixtures.astro
     (Chapter 4/10): the season-select navigation href, every
     gameweek-nav <a> href, the Astro.redirect() call, and the
     data-* driven fetch() calls inside its own <script>.
   - src/pages/admin/predictions.astro (Chapter 5): its own
     submitPrediction() fetch() call.
   - Every place a PATCH/POST fetch() call is made against
     /api/fixtures/{id}/result (Chapter 6) from any admin page.
2. Create a real .env file with PUBLIC_BASE_PATH=/predictor, rebuild
   (npm run build), and redeploy the standalone server exactly as in
   Chapter 11.
3. Add the location /predictor/ block from this chapter to the real
   nginx config, alongside (or replacing) Chapter 11's own /admin/
   block, and reload nginx.
4. Through the real, public-facing URL (https://yourdomain/predictor/...),
   walk through a full real user flow: create a season and teams,
   create a gameweek and a fixture via the click-to-pair UI, submit a
   user/expert/guest/AI prediction, enter a real result, view the real
   league table, and navigate between two different gameweeks using
   the gameweek-nav links. Confirm every single step lands on a
   correctly-prefixed /predictor/... URL and that no request
   accidentally resolves to the site's own bare root.
5. Stop the server, unset PUBLIC_BASE_PATH (or delete the .env file
   entirely), rebuild, and run npm run dev.
6. Repeat the identical user flow at http://localhost:4321/... with no
   /predictor prefix anywhere, and confirm it still works completely
   correctly — every href, redirect, and fetch() call resolves BASE_PATH
   to the empty string via the ?? '' fallback, reproducing exactly the
   original, unprefixed behavior with zero source-code differences
   between the two runs.

WHY THIS WORKS AS AN ANSWER
----------------------------
It completes the real, hands-on integration end to end — updating
every real path-generating location across the app, verifying a full
user flow through the actual mounted reverse proxy, and then
explicitly re-verifying the exact same codebase in its own original,
unprefixed dev configuration — directly confirming the chapter's own
central claim that one environment variable, not a code fork or a
build-time flag, is genuinely sufficient to make the whole app
correctly relocatable.