Three bugs causing 0 articles after generation:
1. Worker never called open_analytics_db() — fetch_analytics always
returned [] since _conn was None. Generation completed silently with
0 rows from DuckDB.
2. generate_articles upserted by url_path alone — after the URL prefix
fix, all languages share the same url_path (e.g. /markets/de/berlin).
The EN article was overwriting the DE article on every generation.
Fixed: deduplicate on (url_path, language).
3. article_page and _filter_articles didn't filter by language — with
shared url_paths a DE request could serve an EN article, and the
markets hub would show duplicate entries per city. Fixed: both now
filter by g.lang from the /<lang> blueprint prefix.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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