Offer "Pseudo-English" (qps-ploc) as a UI language for i18n testing (BL-16748)

[andrew-polk]

Problem

Nothing in Bloom shows which on-screen strings actually go through localization. A hard-coded string, a mangled placeholder, a label the layout will clip once the text grows — all of it looks fine in English, and only surfaces when a translator or a user in another language hits it.

What the PR does

On the developer and alpha channels, the UI Language menu now offers Pseudo-English (i18n test). L10NSharp 10.1.0-beta0001 transforms the live English at lookup time for the standard qps-ploc pseudo-locale — each vowel doubled and accented, the whole string bracketed, so Title Missing becomes [Tîitlée Mîissîing]. A tester then reads the problems straight off the screen: plain English means the string was never internationalized, a visible {0} or %0 means a broken placeholder, a missing ] means truncation, brackets mid-sentence mean the sentence is concatenated at runtime, and clipped layout means we can't absorb the ~30–40% growth real translations bring. No qps-* translation files exist or are ever written.

• Program.SetUpLocalization turns the locale on for the developer and alpha channels only, and GetDesiredUiLanguage falls back to English if a build that doesn't offer the locale nonetheless finds qps-ploc stored, so nobody is left with a mangled UI and no menu entry to escape it.
• WorkspaceView names the locale itself (Palaso's language-name lookup has nothing useful to say about a pseudo-locale) and puts it last in the menu rather than sorting it among real languages.
• I18NApi pseudolocalizes the English fallback it returns for ids that aren't in the English XLIFF. Without this those come back as plain English and are indistinguishable from hard-coded text, which defeats the exercise.
• The locale is excluded from the two places where the list of available localizations feeds book data rather than the UI: the pre-translated content TranslationGroupManager writes into a new book, and the hint-bubble language chooser.
• Several UI strings mark their hyperlink words with [square brackets]. Because pseudo-localization brackets the whole string as well, the five parsers that took the first [ and the next ] swallowed the sentence into the link and ate the wrapper — making those strings look un-internationalized, which is the one thing the locale must never get wrong. A shared findLinkTextBrackets() now anchors on the first ] and takes the nearest [ before it (the innermost pair, correct in both plain and pseudo-localized text), and the markdown link regex no longer allows [ inside link text.
• DistFiles/localization/README.md documents that the locale is runtime-derived, that no qps-* XLF should ever exist, and which surfaces stay plain English on purpose (the whole-file localizations — template readmes, help pages, xmatter descriptions), so the tester's rule stays exact. switchWorkspaceTab.mjs gets a label-independent fast path, since matching a tab by its visible English label fails under this locale.

Ref: https://issues.bloomlibrary.org/youtrack/issue/BL-16748

Devin review

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This change is 

[greptile-apps]

Greptile Summary

Adds the L10NSharp qps-ploc pseudo-locale as a developer/alpha-only UI language for finding internationalization and layout defects.

• Gates pseudo-localization by release channel and normalizes carried-over settings to English on unsupported channels.
• Adds pseudo-locale naming, menu placement, and fallback-string transformation.
• Excludes the pseudo-locale from book-content translation generation and hint-language authoring.
• Adds language-independent workspace-tab automation selectors, documentation, and focused tests.

Important Files Changed

Filename	Overview
src/BloomExe/Program.cs	Configures pseudo-localization before localization-manager initialization and safely falls back to English on channels where it is unavailable.
src/BloomExe/Workspace/WorkspaceView.cs	Adds a stable pseudo-locale label and places it last in the language menu while preserving existing selection behavior.
src/BloomExe/web/I18NApi.cs	Applies pseudo-localization to English fallback responses that bypass normal L10NSharp lookups, while excluding numeric IDs.
src/BloomExe/Book/TranslationGroupManager.cs	Prevents the testing-only pseudo-locale from generating persisted translated content in books.
src/BloomExe/web/controllers/CommonApi.cs	Excludes qps-ploc from the language chooser used to author persistent hint content.
src/BloomBrowserUI/react_components/TopBar/TopBar.tsx	Adds a stable language-independent data attribute to workspace tabs for automation.
.github/skills/bloom-automation/switchWorkspaceTab.mjs	Prefers the new stable workspace-tab selector while retaining legacy label-based fallbacks.
src/BloomTests/Workspace/PseudoLocalizationTests.cs	Covers pseudo-locale naming/completeness and non-development channel gating, though not the I18N fallback branches.
src/BloomExe/BloomExe.csproj	Upgrades L10NSharp to the beta version providing runtime pseudo-localization support.

_{Reviews (1): Last reviewed commit: "Merge remote-tracking branch 'origin/mas..." | Re-trigger Greptile}

[andrew-polk]

[Claude Opus 5 (1M context) during preflight] Consulted Devin on 2026-09-02 18:29 UTC up to commit c64f5ade54ef2a5c3c2a23bc14a8d658319b37d7.

Clean: no bugs, no Investigate flags, no informational items. Nothing to mirror.

[andrew-polk]

[Claude Opus 5 (1M context) from Andrew Polk's machine during preflight] Consulted Devin on 2026-09-11 18:53 UTC up to commit db7c2aa9c1.

It raised one Bug and two Investigate flags, each its own resolved thread:

• Release startup restores hidden pseudo-locale — not an issue; the fix it prompted has been reverted. The finding assumes a Release build can inherit an Alpha's settings, and it cannot: settings are stored per Bloom<channel> product folder and the previous-version search never leaves the running build's own folder. Reasoning on the thread.
• PR bypasses required release branch — not an issue; targeting master was already decided and is recorded on BL-16748. (thread)
• Automation selector description is stale — correct, and the PR description was rewritten; the code was always right. (thread)

No Informational items either round. CI (pr-automation) is green.

Note the branch has since been collapsed to a single commit, so db7c2aa9c1 is no longer on it.