Reduce the styles admin page to a pure action endpoint (UX-01, DEC-0067)

[erseco]

What

Resolves finding UX-01 of the external validation of release 4.0.2 by removing the surface it lived on: admin/styles.php stops being a visible management page and becomes a pure action endpoint. Styles are now managed in exactly one place — the plugin settings page, where everything already worked.

The problem

Styles were managed in two places at once. The settings page renders the three widgets inside the settings form, so the upload control installs on "Save changes". admin/styles.php re-rendered the same widgets bare, via output_html('') — and its upload control had no form and no save button: a dropped ZIP looked accepted, was never installed, and vanished on reload without a message. The validation reviewers hit this themselves during testing.

Why the file survives at all

The per-row enable/disable/delete buttons — including the ones rendered on the settings page — are sesskey-protected GET links pointing at admin/styles.php, because a <form> nested inside the settings-page form is invalid HTML and used to break the whole settings save (fixed back in the audit round by turning the buttons into links). Those links need a handler outside the settings form, and this is it.

Changes

• admin/styles.php keeps only the action processing and the server-side delete confirmation (the one screen it still renders — a GET delete must not fire on a prefetch); every outcome, including a direct visit with no action, redirects to the settings page.
• The admin_externalpage registration stays — admin_externalpage_setup() resolves it — but hidden from the admin menu.
• The duplicated widget rendering is gone, and with it the orphan upload control; the docblock now warns against growing a UI here again.
• README and the user guide no longer advertise a dedicated styles page.
• ADR DEC-0067 records the decision and the rejected alternatives (wrapping the orphan control in its own form — the report's option a — keeps two parallel managers of the same state; own POST forms inside settings are impossible without nesting).

Action-link URLs are unchanged, so nothing migrates; a bookmarked admin/styles.php lands on the settings page instead of erroring.

Tests

Written first and watched failing: the styles admin page must remain registered (an admin_externalpage) but hidden. The existing render test — action buttons emitted as links into styles.php, no nested form — still passes unchanged: 3/3 locally (Moodle 5.0.7 / PHP 8.3 / MariaDB), phpcs --standard=moodle 0/0 on every touched file.

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Moodle Playground Preview

The changes in this pull request can be previewed and tested using a Moodle Playground instance.

ℹ️ The eXeLearning editor is fetched from the shared release and unpacked into the plugin when the playground boots, so the first load may take a few extra seconds. ELPX upload, viewer and preview work normally.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.31%. Comparing base (7f45737) to head (df4bf34).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##               main     #110   +/-   ##
=========================================
  Coverage     92.31%   92.31%           
  Complexity      824      824           
=========================================
  Files            51       51           
  Lines          3734     3734           
=========================================
  Hits           3447     3447           
  Misses          287      287           

Flag	Coverage Δ
javascript	94.11% <ø> (ø)
php	92.23% <ø> (ø)

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Components	Coverage Δ
PHP (server-side)	92.23% <ø> (ø)
JavaScript (SCORM tracker)	94.11% <ø> (ø)

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