[fredbi]

Fixes #550.

Problem

docui.Redoc loaded its bundle from https://cdn.redoc.ly/redoc/latest/..., which now serves Redoc 3.0.1. The v3 standalone bundle is an ES module: it ends with export{RedocStandalone,hydrate,init} and uses import.meta. Our template loaded it with a classic <script src>, so the browser threw Uncaught SyntaxError: Cannot use 'import.meta' outside a module and the page stayed blank.

Fix

• The default Redoc template now uses <script type="module">. v3 still finds the <redoc spec-url=...> element on load and calls init, so nothing else in the template changes.
• The default bundle URL is pinned to https://cdn.jsdelivr.net/npm/redoc@3/bundles/redoc.standalone.js instead of latest, so a future major release cannot break the page again. (cdn.redoc.ly/redoc/v3/... returns 403; jsdelivr resolves @3 to the latest v3.)
• New option docui.WithRedocV2(). It restores the classic-script template and defaults the URL to redoc@2. WithUITemplate and WithUIAssetsURL still override both, in any argument order.
• The deprecated middleware.RedocOpts gets a RedocV2 field mapped to WithRedocV2(), for callers of middleware.Redoc.
• Doc site: new default URL, plus a short "Redoc v2" section and a row in the shim mapping table.

Why v2 needs an option

type="module" breaks the v2 bundle. Its UMD wrapper is !function(e,t){... e.Redoc=t(e.null)}(this, ...). In a module, top-level this is undefined, so e.null throws before Redoc starts.

Compatibility

• Default settings: already broken on v3; fixed by this PR.
• Custom template: unchanged.
• WithUIAssetsURL (or RedocOpts.RedocURL) pointing at a v2 bundle with the default template: worked before, now renders blank. Add WithRedocV2() (or RedocV2: true). This needs a release note.

Verification

Besides the unit tests, I rendered the pages in headless Chromium against a small spec: the default page (v3) and the WithRedocV2() page (v2) both render it. The classic template with the v3 bundle renders nothing, which reproduces the bug.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.14%. Comparing base (80fa728) to head (8bb9918).
⚠️ Report is 3 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #552      +/-   ##
==========================================
+ Coverage   87.10%   87.14%   +0.04%     
==========================================
  Files          65       65              
  Lines        4752     4762      +10     
==========================================
+ Hits         4139     4150      +11     
  Misses        602      602              
+ Partials       11       10       -1     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.