A capability stays maintainable only when the team can explain every state, retry, and piece of residual data—not merely show one successful run. English may double a button’s width and change wrapping. Locale also affects reading speed, search vocabulary, and dates; shrinking the font is not a localization strategy.
Frontend architecture is about state ownership, repeatable events, invalidation of stale async work, and cleanup after unmount—not the shape of the source directory.
Questions the design must answer
This capability crosses clients, networks, and servers, so a local optimization can create a system failure. Decisions must constrain both endpoints, persisted truth, and operating budgets together.
- Use flexible layouts and sensible minimums so text wraps without pushing actions offscreen.
- Generate dates, numbers, units, and plurals through Intl and message parameters.
- Maintain a bilingual technical glossary across navigation, errors, and articles.
Good localization feels native in both languages: layout leaves room, locale owns formatting, and one content contract owns terms and URLs.
Edge cases are part of the feature
Prioritize faults that silently preserve false facts: the interface looks recovered while a queue, permission, or counter has diverged. The defect often appears only on the next action.
- The whole site drops to 12px to fit English and makes Chinese hard to read.
- Language changes text but leaves the other-locale blog URL and mismatched canonical.
- Missing keys fall back to Chinese and expose raw sensitive errors in English UI.
Prove that it works with evidence
Write the expected state trace before injecting faults. At every phase, reconcile user-visible outcome, both protocol endpoints, persistent records, and resource counts to prove the loop.
- Test longest real copy on narrow screens, 200 percent zoom, and large text.
- Audit static keys, runtime parameters, and localized SEO titles for missing or duplicate values.
- Switch locale on every page and verify URL, hreflang, focus, and back navigation alignment.
The release standard is practical: the normal path is fast, abnormal paths converge, recovery never overrides an explicit user decision, and operators can diagnose faults from limited, privacy-safe evidence.