[rpgmem]

Closes #2056

Problem

On the testing site, /valid/?ffc_device_check=1 stays at "Checking…" on every row for visitors who are not logged in, on phones and on desktop. A logged-in administrator sees it work.

LiteSpeed Cache minifies and combines scripts for guests through matthiasmullie/minify. That minifier misreads a regex literal that ends in an escaped slash when it is followed by ] or a line break: it closes the literal early and drops the rest of the line. The combined file on the site has ['LINE',/Line\];var BRANDS=…, from ['LINE', /Line\//] (#2053). The file stops parsing ("Invalid regular expression: missing /"), so no script in it runs.

Change

• The three literals of that shape now end in \/\d or \/{2}:

  • ffc-device-check.js;
  • ffc-core.js (the in-app browser check);
  • ffc-preflight.js (the Android "open in Chrome" link).

  The last two survive the minifier today only because of the character that follows them.

• MinifierSafeRegexTest refuses a regex literal ending in an escaped slash in assets/js/. The rule is wider than the measured trigger on purpose: which characters may follow the literal safely is the minifier's business.

Tests

• Reproduced locally with matthiasmullie/minify: the same output as the site's combined file.
• After the fix, every readable script (assets/js/*.js and libs/js/*.js, 118 files) and every *.min.js (114) goes through that minifier and still parses (node --check).
• MinifierSafeRegexTest:
  • fails with the three files listed when the JS change is reverted, and passes with it;
  • its canary pins both sides;
  • a scandir recount checks that it reads every script.
• Full Vitest run: 164 files, 2,557 tests. The in-app UA corpus (Line/14.13.0) still detects LINE.
• ESLint and PHPCS (tests ruleset) are clean.

Checklist

• Base is develop; no version bump
• CHANGELOG.md — one bullet at the end of Fixed, citing the issue
• Documentation topic — not applicable
• Strings — none changed
• Minified assets rebuilt
• Fast checks run locally

---

Generated by Claude Code