fix(i18n): add unique keys to duplicate sidebar categories

[thetaPC]

Issue URL: N/A

What is the current behavior?

The production build fails on main. docusaurus build completes en and then throws on ja:

[ERROR] Error: Unable to build website for locale ja.
  [cause]: Error: Multiple docs sidebar items produce the same translation key.
  - `sidebar.docs.category.Build Your First App`: 3 duplicates found

Three sidebar categories, one per framework, all use the label "Build Your First App". Docusaurus derives a category's translation id as sidebar.docs.category.${category.key ?? category.label}, so all three collapse onto a single id.

What is the new behavior?

Each of those categories gets a unique key, so each gets its own translation id and the ja build succeeds:

label: 'Build Your First App',
key: 'angular-your-first-app',

Six additions in two files: sidebars.js (current/v8) and versioned_sidebars/version-v7-sidebars.json. Labels are untouched, so the sidebar looks identical.

Does this introduce a breaking change?

• Yes
• No

Other information

Why the React 19 upgrade surfaced this

React 19 did not introduce the duplicate labels, which have been there for years. It forced the Docusaurus bump that turned them into an error. @docusaurus/plugin-debug@3.7.0 pinned react-json-view-lite: ^1.2.0, and no 1.x release of that package supports React 19, so clearing the last peer warning required moving the Docusaurus family to 3.10.2. Somewhere in that range Docusaurus added the ensureNoSidebarDuplicateEntries validation: it appears 0 times in plugin-content-docs@3.7.0 and twice in 3.10.2. What was previously tolerated, three categories silently sharing one translation string, is now fatal.

Why it was not caught before merging

Two things hid it, and both are worth fixing separately. First, build:preview is docusaurus build --locale en while only build:production builds all locales, so no PR preview has ever exercised ja. Second, even building ja locally passes, because Docusaurus infers whether to translate from whether i18n/<locale> exists, and that directory is only created on CI by scripts/i18n.sh during prebuild. Creating an empty i18n/ja locally reproduces the failure exactly, which is how this fix was verified: failing before, passing after.

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Project	Deployment	Actions	Updated (UTC)
ionic-docs	Ready	Preview	Aug 6, 2026 9:57pm