feat: add i18n category (i18next, next-intl)

[Marve10s]

Summary

• Adds Internationalization (i18n) as a new TypeScript ecosystem category with two options:
  • i18next: Full-featured i18n framework, works with all frontends (React, Svelte, Solid, Vue, etc.)
  • next-intl: Lightweight i18n for Next.js with App Router support (Next.js only)
• Follows Scenario B (new category) from the adding-new-tool-options guidelines -- full ~30 file checklist

Files changed (33 files, ~142 lines added)

Schema/types (4 files)

• packages/types/src/schemas.ts -- I18nSchema + all 3 config schemas + VALUES export
• packages/types/src/types.ts -- I18n type alias
• packages/types/src/option-metadata.ts -- OptionCategory, CATEGORY_VALUE_IDS, EXACT_LABEL_OVERRIDES, OPTION_CATEGORY_METADATA
• packages/types/src/compatibility.ts -- CompatibilityCategory, CompatibilityInput, TYPESCRIPT_CATEGORY_ORDER, getDisabledReason (next-intl requires Next.js)

CLI wiring (8 files)

• apps/cli/src/index.ts -- 4 spots: import, router schema, config construction, prompt
• apps/cli/src/prompts/i18n.ts -- NEW interactive prompt (shows next-intl only when Next.js selected)
• apps/cli/src/prompts/config-prompts.ts -- Import, PromptGroupResults type, navigable group, return mapping
• apps/cli/src/mcp.ts -- 6 spots: import, SCHEMA_MAP, ECOSYSTEM_CATEGORIES, buildProjectConfig, buildCompatibilityInput, tool params
• apps/cli/src/utils/bts-config.ts -- write + read paths
• apps/cli/src/constants.ts -- DEFAULT_CONFIG_BASE
• apps/cli/src/helpers/core/command-handlers.ts -- error fallback config
• apps/cli/src/utils/generate-reproducible-command.ts -- --i18n flag
• apps/cli/src/utils/config-processing.ts -- processFlags branch

Web builder (8 files)

• apps/web/src/lib/constant.ts -- TECH_OPTIONS + ECOSYSTEM_CATEGORIES
• apps/web/src/lib/preview-config.ts -- stackToConfig mapping
• apps/web/src/lib/stack-defaults.ts -- StackState type + DEFAULT_STACK
• apps/web/src/lib/stack-url-keys.ts -- URL key i18n: "i18n"
• apps/web/src/lib/stack-url-state.ts -- 3 spots: load, serialize, searchToStack
• apps/web/src/lib/stack-utils.ts -- TYPESCRIPT_CATEGORY_ORDER + generateStackCommand
• apps/web/src/lib/tech-icons.ts -- i18next + next-intl icons
• apps/web/src/lib/tech-resource-links.ts -- docs + GitHub URLs
• apps/web/public/icon/next-intl.svg -- NEW SVG icon

Template generator (6 files)

• packages/template-generator/src/utils/add-deps.ts -- dependency versions (i18next, react-i18next, next-intl, etc.)
• packages/template-generator/src/processors/i18n-deps.ts -- NEW dependency processor
• packages/template-generator/src/processors/index.ts -- wire processor
• packages/template-generator/src/template-handlers/i18n.ts -- NEW template handler
• packages/template-generator/src/template-handlers/index.ts -- export handler
• packages/template-generator/src/generator.ts -- wire handler call

Templates (7 files)

• templates/i18n/i18next/web/base/src/i18n/config.ts.hbs -- i18next config with language detector
• templates/i18n/i18next/web/base/public/locales/en/common.json -- English translations
• templates/i18n/i18next/web/base/public/locales/fr/common.json -- French translations
• templates/i18n/i18next/web/react/src/i18n/provider.tsx.hbs -- React I18nextProvider wrapper
• templates/i18n/next-intl/web/base/src/i18n/config.ts.hbs -- locale config
• templates/i18n/next-intl/web/base/src/i18n/request.ts.hbs -- next-intl server request config
• templates/i18n/next-intl/web/base/messages/{en,fr}.json -- translation files

Tests (4 files)

• apps/cli/test/test-utils.ts -- I18n type import + coreStackDefaults
• apps/cli/test/generate-reproducible-command.test.ts -- i18n field in makeConfig defaults
• testing/lib/generate-combos/options.ts -- I18N_VALUES import + sampleScalar + base config
• testing/lib/presets.ts -- i18n default in makeBaseConfig

Compatibility

• next-intl is disabled (greyed out) when frontend is not Next.js
• i18next works with all frontends

Verification

• bun run --filter=@better-fullstack/types build -- passes
• bun run --filter=@better-fullstack/template-generator generate-templates -- passes (1046 templates)
• bun run --filter=@better-fullstack/template-generator build -- passes
• bun run --filter=create-better-fullstack build -- passes (publint clean)
• bun test apps/cli/test/cli-builder-sync.test.ts -- 358 pass, 0 fail
• bun test apps/cli/test/generate-reproducible-command.test.ts -- 5 pass, 0 fail
• bun run --cwd apps/cli check-types -- passes
• bun run --cwd apps/web typecheck -- passes
• bun run --cwd apps/web validate:tech-links -- passes (no missing icons/links)

Scaffold tests (3 combos)

All scaffolded with bun install && bun run check-types:

• i18next + Next.js + Hono -- type-checks clean
• i18next + TanStack Router + Hono -- type-checks clean
• next-intl + Next.js + Hono -- type-checks clean

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
better-fullstack-web	Ignored		Apr 10, 2026 8:09pm