vietnamese-landing-copy

Vietnamese landing-page copy (vi-VN)

Vietnamese is a low-resource language for LLMs. Left unguided, output defaults to English-calqued translationese: fluent-sounding but obviously machine-written. It picks the wrong pronoun, translates CTAs word-for-word, writes illegal advertising superlatives, and formats currency the American way. Every rule below exists to stop a specific, observed defect.

Step 1 — Pick the register before writing a single word

Vietnamese has no neutral "you." The pronoun is the first decision, not a detail.

Audience	Address the reader as	Vocabulary
Real estate, finance, luxury, airlines, healthcare	quý khách	Hán-Việt heavy, ornate
Institutional, government, broadcast announcements	quý vị	Formal, plural
Sales consulting, mid-market services, local business	anh/chị	Warm, respectful
SaaS, tech, e-commerce, youth brands	bạn	Thuần Việt, terse
Policy, terms, descriptive prose (never direct address)	khách hàng	Neutral 3rd person

If the brief does not say, infer from the product. A căn hộ cao cấp page is quý khách. A developer tool is bạn. Never mix two registers in one page — that is the single most visible amateur tell.

Full pronoun matrix, including the registers the other Vietnamese skills use: references/register-matrix.md. The Hán-Việt vs thuần Việt prestige axis, classifiers, and the section-order house style: references/register-guide.md

Step 2 — Core rules (non-negotiable, no file hop needed)

1. Emit NFC Unicode. Precomposed ế (U+1EBF), never base + combining marks. NFD breaks web font rendering and string length. Normalize everything you output.
2. Pick one tone-mark style and hold it for the whole document. Default to kiểu mới (hoà, thuỷ, khoẻ) matching post-2022 Bộ GD&ĐT textbooks. Kiểu cũ (hòa, thủy, khỏe) is equally correct and still dominant commercially — match the client's existing site when there is one. Neither is wrong. Inconsistency within one page is the defect.
3. Modifier follows the noun. căn hộ cao cấp, never cao cấp căn hộ.
4. Recast English passives. được thiết kế bởi X → do X thiết kế, or make it active: X kiến tạo.
5. Never write số 1, tốt nhất, duy nhất, hàng đầu as an unproven claim. This is illegal under Điều 8 khoản 11 Luật Quảng cáo 16/2012/QH13, not merely tacky. Real fines, currently issued. See references/banned-phrases.md.
6. Vietnamese has no grammatical plural. ICU messages take only other. An one {} branch in vi.json is always a bug.
7. Write CTAs from the conventional list, not from the English. Learn more is Tìm hiểu thêm, never Học thêm.

Step 3 — Look up the conventional wording

Do not invent Vietnamese for a UI string that already has a settled convention. The EN→VI table covers CTAs, nav labels, form fields, and the standardized real-estate section names (Tổng quan dự án, Vị trí, Tiện ích, Mặt bằng, Tiến độ, Chính sách bán hàng, Chủ đầu tư, Pháp lý).

references/glossary.md

Step 4 — Format numbers, dates, and locale data correctly

VND groups with periods and decimalizes with commas: 2.500.000 ₫. Real-estate prices are colloquial: Chỉ từ 2,5 tỷ, 35 triệu/m². Dates are dd/MM/yyyy. Phones are 0xxx xxx xxx or +84. Addresses run small-to-large. Slugs are unaccented, lowercase, hyphenated.

references/locale-formatting.md — also covers Intl.NumberFormat('vi-VN'), BCP-47 tags, font subsets and stacked-diacritic typography, and the accented/unaccented dual-keyword SEO rule. The NFC and tone-mark rules behind points 1 and 2 above are in references/unicode-and-tone.md.

Step 5 — Get the legal copy right

Lead forms are regulated. Nghị định 13/2023/NĐ-CP requires express, informed, revocable consent with a stated purpose and a linked Chính sách bảo mật. Advertising superlatives require documented proof.

references/legal-copy.md and references/banned-phrases.md for the landing-page specifics; references/compliance.md for the cross-cutting advertising, consent, promotion and anti-spam rules every Vietnamese skill shares.

Step 6 — Validate, fix, then ship

Run the validator immediately after writing. If it reports errors, fix them and run again. Only present the copy once it passes. Do not skip this because the output "looks fine" — NFC violations and comma-grouped numbers are invisible to reading.

python scripts/validate_copy.py path/to/copy.md --register re

• --register re|saas|formal|consult enables the register-consistency check.
• Exit 0 = clean or warnings only. Exit 1 = errors that must be fixed.
• --json for machine-readable findings; --strict to fail on warnings too.
• --fix rewrites NFC violations in place; every other rule is a human judgement call.

Check glyph coverage when a specific web font is specified:

python scripts/check_font_coverage.py path/to/copy.md

If a flagged superlative is backed by a licensed market survey or award certificate, keep it and annotate the source instead of deleting it:

Thương hiệu số 1 Việt Nam <!-- proof: Khảo sát Nielsen VN 2026, chứng chỉ số 123/NS -->

Step 7 — Learn from the worked pairs

Before writing anything long, read the bad→good corpus. Each pair names which failure mode it fixes, and the diagnosis generalizes further than the string does.

references/examples.md

For structured localization files, start from assets/vi.json.template — next-intl shaped, both registers, other-only plurals.

For human review before publishing: references/qa-checklist.md

Quick self-check

Before returning Vietnamese copy, confirm:

• One register throughout; the pronoun matches the audience.
• Every CTA is from the glossary, not translated fresh.
• No unproven superlative anywhere on the page.
• Prices grouped with ., decimals with ,, ₫ or tỷ/triệu colloquial form.
• Dates dd/MM/yyyy, phones 0xxx/+84, address small-to-large.
• One tone-mark style, consistently.
• Lead form has a consent checkbox, a purpose statement, and a privacy-policy link.
• validate_copy.py exits clean.