We need to output valid JSON with fields: seo_title, summary, key_entities (companies, people, locations), expert_faq (question, answer), internal_link_anchor, primary_keyword, secondary_keywords, content_type.

We must produce summary 180-250 words total across 3-4 paragraphs, each paragraph 45-65 words, separated by \n\n in JSON string. Must include bold formatting with double asterisks for 3-5 key details across whole summary. Must not use banned words etc. Must not refuse. Must include key entities with only those mentioned in source. Must include expert_faq with question and answer 30-50 words. Must include internal_link_anchor (2-4 word phrase). Must include primary_keyword (single most important 2-3 word phrase). Must include secondary_keywords (3-5). Must include content_type.

We need to bold some key details: likely Meta, WhatsApp, username, maybe 500 million, 14 days? But only 3-5 bolded terms across entire summary, not per paragraph. So we need to choose maybe Meta, WhatsApp, username, 500 million, 14 days? That's 5. Use bold only on these. Use double asterisks.

We must ensure summary length 180-250 words total. Count words.

We need 3-4 paragraphs each 45-65 words. Let's aim for 4 paragraphs of about 50 words each => total ~200 words.

Paragraph 1: talk about Meta's announcement of username feature, rollout, reservations open, scramble. Paragraph 2: steps to reserve on iOS/Android, restrictions (unique, length 3-35, characters). Paragraph 3: privacy concerns, scams, Indian government pushback, 500 million users. Paragraph 4: closing concrete statement about impact.

We need to embed bold terms across paragraphs. Let's decide bold terms: Meta, WhatsApp, username, 500 million, 14 days. That's 5 bold terms. Use them exactly as bold.

We must ensure we bold only those terms, not extra. Use Meta, WhatsApp, username, 500 million, 14 days. That's 5 bold terms, okay.

Now craft