nostr: raise news cap to 18 so English variant survives multi-language batches

A single news post now ships as nine per-`d` language variants and the
publisher emits English first, giving it the oldest `created_at` in the
batch. With the store capped at 8 events across all d-tags, the English
event was always the 9th-newest and got evicted — English readers saw no
news. The catch-up/subscription filter also capped fetches at 4, so fresh
installs only ever received the newest four events.

Raise NEWS_CAP from 8 to 18 (two full nine-language posts) and bump the
news filter limit from 4 to 18 to match. Selection logic is unchanged.
Extend the reconcile_news test with a nine-variant batch that proves the
untagged English event survives under the real cap.

src/nostr/client.rs

@@ -1387,7 +1387,7 @@ async fn run_service(svc: Arc<NostrService>, wallet: Wallet) {
 		Filter::new()
 			.kind(Kind::LongFormTextNote)
 			.author(pk)
-			.limit(4)
+			.limit(18)
 	});
 
 	if let Ok(events) = client

src/nostr/store.rs

@@ -30,8 +30,10 @@ use crate::nostr::types::*;
 const PROCESSED_TTL_SECS: i64 = 30 * 86_400;
 
 /// Cap on stored news posts (newest kept, older pruned) — the panel only ever
-/// shows the latest, so this is just a small archive bound.
-const NEWS_CAP: usize = 8;
+/// shows the latest, so this is just a small archive bound. Sized for two full
+/// nine-language posts so the oldest-`created_at` variant (English is published
+/// first) is not evicted before its readers see it.
+const NEWS_CAP: usize = 18;
 
 /// Nostr metadata archive for a wallet.
 pub struct NostrStore {
@@ -385,12 +387,16 @@ mod tests {
 	use super::*;
 
 	fn item(d: &str, created_at: i64) -> NewsItem {
+		item_lang(d, created_at, None)
+	}
+
+	fn item_lang(d: &str, created_at: i64, lang: Option<&str>) -> NewsItem {
 		NewsItem {
 			d: d.to_string(),
 			created_at,
 			title: format!("t{created_at}"),
 			summary: String::new(),
-			lang: None,
+			lang: lang.map(str::to_string),
 			published_at: None,
 		}
 	}
@@ -418,4 +424,28 @@ mod tests {
 		assert_eq!(all[0].created_at, 9);
 		assert_eq!(all[2].created_at, 7);
 	}
+
+	#[test]
+	fn nine_language_batch_retains_english_under_news_cap() {
+		// A single post now ships as nine per-`d` language variants. The
+		// publisher emits English FIRST, so the untagged (lang == None) English
+		// event carries the OLDEST `created_at` in the batch. Under the real
+		// `NEWS_CAP` the whole batch must survive so English readers see it.
+		let langs = ["es", "fr", "de", "it", "pt", "ja", "zh", "ko"];
+		let mut all = vec![];
+		// English published first → oldest created_at, no lang tag.
+		all = reconcile_news(all, item_lang("post-en", 100, None), NEWS_CAP);
+		for (i, code) in langs.iter().enumerate() {
+			all = reconcile_news(
+				all,
+				item_lang(&format!("post-{code}"), 101 + i as i64, Some(code)),
+				NEWS_CAP,
+			);
+		}
+		assert_eq!(all.len(), 9);
+		assert!(
+			all.iter().any(|n| n.d == "post-en" && n.lang.is_none()),
+			"untagged English variant must survive the cap"
+		);
+	}
 }