Try a feed again in minutes when its host could not be looked up for the moment (#143)

205 of the Directory's 208 feeds without a category had never been read: on 2026-10-05 at 03:24
UTC every one failed with "dns error: ... Temporary failure in name resolution" within a minute,
during an outage on Tower that also stopped iPX's log reaching Loki until Tower rebooted at 11:56.
They are working podcasts, NPR's, Megaphone's, Acast's, which resolve now. A feed nobody
subscribes to is read once a day and a failing one backs off up to a day (#99), so each sat
failing, unread and so uncategorised (#117) until the next day, and explain_failure called every
DNS error "This address no longer resolves; the site is gone.", on its page and since #142 on its
Directory page. A forced check of the 208 read 205; each has its items, its description and its
own category now.

A temporary lookup failure, EAI_AGAIN, is not recorded on the feed at all: no last_error, no
error_since to back off from or call it gone by. The daemon notes it in Ctx::retry and the feed
is due again in ten minutes, which the scan's due check and the sleep until the next scan both
honour; a restart forgets it, which only makes the retry sooner. A name that does not exist is
still the feed's error, explained as "may be gone", and the Directory page, like the feed's own,
names a cause only once a feed has been failing a day; before that its last check failed.

The page also drops "Nobody here subscribes yet", which said nothing worth a line.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- A feed's page in the Directory says how many people here subscribe only when someone does, without "Nobody here subscribes yet".
+
+### Fixed
+
+- A moment's DNS failure no longer marks a feed as failing for a day or calls it gone: iPX tries it again in ten minutes. One failed lookup one morning left 205 podcasts unread, uncategorised and labelled gone until the next day. A name that does not resolve is said to be maybe gone, and only once it has been failing a day, on its Directory page as on its own.
+
 ## [0.10.2] - 2026-10-05
 
 ### Fixed

docs/configuration.md

@@ -54,7 +54,8 @@ database as described above; `download_dir`, `socket` and `organize` stay in con
 * **`schedule`** — how often feeds are re-checked. A feed's own `<ttl>` still wins when it asks to
   be polled *less* often, and a per-feed `schedule` overrides both. A feed that keeps failing
   waits as long as it has been failing before the next try, up to a day, and is back on schedule
-  after its first success. Admin-only from the UI.
+  after its first success. A moment's failure to look its host up does not count: the network, not
+  the feed, failed, and it is tried again in ten minutes. Admin-only from the UI.
 * **`organize`** — `feed` files downloads under the feed's folder; `date` under `YYYY-MM-DD`.
 * **`max_total_gb`** — the reaper deletes to get back under this, oldest first, keeping a 50 MB
   pad. Kept items are never deleted, and a file only counts as read once every subscriber has

src/feed.rs

@@ -196,15 +196,25 @@ pub fn explain_failure(msg: &str) -> Option<Failure> {
     if low.contains("http 402") {
         return Some(Failure { reason: "The feed now needs a paid plan.", new_url: None });
     }
-    if low.contains("dns error")
-        || low.contains("failed to lookup address")
-        || low.contains("no address associated")
+    // Only a name that does not exist. A lookup that failed for the moment says nothing about the
+    // site, and NPR's and Megaphone's feeds were labelled gone after a DNS outage (#143).
+    if !is_temporary_lookup_failure(msg)
+        && (low.contains("dns error") || low.contains("failed to lookup address") || low.contains("no address associated"))
     {
-        return Some(Failure { reason: "This address no longer resolves; the site is gone.", new_url: None });
+        return Some(Failure { reason: "This address no longer resolves; the site may be gone.", new_url: None });
     }
     None
 }
 
+/// A host that could not be looked up for the moment -- the resolver's EAI_AGAIN, glibc's
+/// "Temporary failure in name resolution", musl's "Try again" -- as against a name that does
+/// not exist ("Name or service not known"). It says the network was not answering, not that the
+/// feed is gone (#143).
+pub fn is_temporary_lookup_failure(msg: &str) -> bool {
+    let low = msg.to_ascii_lowercase();
+    low.contains("dns error") && (low.contains("temporary failure in name resolution") || low.contains("try again"))
+}
+
 /// True when a body is an OPML document rather than a feed.
 ///
 /// The original matched on the URL ending in ".opml" (iPXClass.py:34), which misses an
@@ -1317,8 +1327,13 @@ mod tests {
             explain_failure("the feed's address answered with nothing at all").unwrap().reason,
             "This address answers with nothing; the site may be gone."
         );
-        let dns = explain_failure("connecting: dns error: failed to lookup address information").unwrap();
-        assert_eq!(dns.reason, "This address no longer resolves; the site is gone.");
+        let dns = explain_failure("connecting: dns error: failed to lookup address information: Name or service not known").unwrap();
+        assert_eq!(dns.reason, "This address no longer resolves; the site may be gone.");
+        // A lookup that failed for the moment is not a site gone (#143).
+        let blip = "connecting: dns error: failed to lookup address information: Temporary failure in name resolution";
+        assert!(is_temporary_lookup_failure(blip));
+        assert!(explain_failure(blip).is_none());
+        assert!(!is_temporary_lookup_failure("connecting: dns error: failed to lookup address information: Name or service not known"));
         let moved = explain_failure("got a web page, not a feed; it links https://x/feed as its feed").unwrap();
         assert_eq!(moved.new_url.as_deref(), Some("https://x/feed"));
         assert!(explain_failure("got a web page, not a feed").unwrap().new_url.is_none());

src/main.rs

@@ -141,9 +141,38 @@ pub struct Ctx {
     /// stops every feed scan, every HTTP download and every status command behind it.
     /// A one-shot CLI run keeps them inline, or the process would exit mid-download.
     pub detach_torrents: bool,
+    /// Feeds whose host could not be looked up for the moment, and when to try them again: a
+    /// failure that says nothing about the feed, kept off it and out of the database (#143).
+    /// Forgotten on a restart, which only makes the retry sooner.
+    pub retry: std::sync::Mutex<std::collections::HashMap<String, i64>>,
 }
 
+/// How soon a feed whose host could not be looked up is tried again (#143).
+const RETRY_LOOKUP_SECS: i64 = 600;
+
 impl Ctx {
+    /// When a feed is next due, taking a lookup retry into account: not before it.
+    fn due(&self, cfg: &config::Config, feed: &config::Feed, id: &str, state: &db::HttpState, subscribed: bool) -> Option<i64> {
+        let at = due_at(cfg, feed, state, subscribed);
+        match self.retry.lock().unwrap().get(id) {
+            Some(&retry) => Some(at.unwrap_or(0).max(retry)),
+            None => at,
+        }
+    }
+
+    /// A scan's failure, recorded on the feed, unless it was only a moment's failure to look its
+    /// host up: on 2026-10-05 a DNS outage on Tower failed 204 feeds in a minute with
+    /// "Temporary failure in name resolution", and each, read once a day and backed off as a
+    /// failing feed, sat a day failing, unread and labelled gone (#143). Tried again in minutes
+    /// instead, with nothing on the feed to say it failed.
+    async fn feed_failed(&self, id: &str, url: &str, msg: &str) -> Result<()> {
+        if feed::is_temporary_lookup_failure(msg) {
+            self.retry.lock().unwrap().insert(id.to_owned(), db::now() + RETRY_LOOKUP_SECS);
+            return Ok(());
+        }
+        self.db.set_feed_error(id, url, msg).await
+    }
+
     pub fn cfg(&self) -> std::sync::Arc<config::Config> {
         self.cfg.read().unwrap().clone()
     }
@@ -275,6 +304,7 @@ async fn main() -> Result<()> {
         torrent_slots: Arc::new(tokio::sync::Semaphore::new(2)),
         config_path: config_path.clone(),
         detach_torrents: is_daemon,
+        retry: Default::default(),
     });
 
     let result = match cli.command {
@@ -1093,7 +1123,7 @@ async fn fetch(ctx: &Arc<Ctx>, only: Option<&str>, force: bool, scope: &[String]
             state.last_modified = None;
         }
 
-        if !force && let Some(at) = due_at(&cfg, &sub.cfg, &state, subscribed.contains_key(id)) {
+        if !force && let Some(at) = ctx.due(&cfg, &sub.cfg, id, &state, subscribed.contains_key(id)) {
             if at > db::now() {
                 ctx.out.emit(Event::FeedSkip {
                     feed: id.clone(),
@@ -1165,7 +1195,7 @@ async fn fetch(ctx: &Arc<Ctx>, only: Option<&str>, force: bool, scope: &[String]
                 // One bad feed must not end the scan.
                 let msg = format!("{e:#}");
                 ctx.out.emit(Event::FeedError { feed: id.clone(), msg: msg.clone() });
-                ctx.db.set_feed_error(id, &feed_cfg.url, &msg).await?;
+                ctx.feed_failed(id, &feed_cfg.url, &msg).await?;
             }
         }
     }
@@ -1191,7 +1221,7 @@ async fn fetch(ctx: &Arc<Ctx>, only: Option<&str>, force: bool, scope: &[String]
                 Err(e) => {
                     let msg = format!("{e:#}");
                     ctx.out.emit(Event::FeedError { feed: id.clone(), msg: msg.clone() });
-                    ctx.db.set_feed_error(id, &feed_cfg.url, &msg).await?;
+                    ctx.feed_failed(id, &feed_cfg.url, &msg).await?;
                 }
             }
         }
@@ -1329,7 +1359,9 @@ async fn until_next_scan(ctx: &Ctx) -> std::time::Duration {
                 .iter()
                 // A feed with no row yet has never been checked: due now.
                 .map(|s| {
-                    states.get(&s.id).and_then(|st| due_at(&cfg, &s.cfg, st, subscribed.contains_key(&s.id))).unwrap_or(0)
+                    let never = db::HttpState::default();
+                    let state = states.get(&s.id).unwrap_or(&never);
+                    ctx.due(&cfg, &s.cfg, &s.id, state, subscribed.contains_key(&s.id)).unwrap_or(0)
                 })
                 .min(),
         )
@@ -2283,9 +2315,27 @@ mod tests {
             torrent_slots: Arc::new(tokio::sync::Semaphore::new(2)),
             config_path: PathBuf::new(),
             detach_torrents: false,
+            retry: Default::default(),
         }
     }
 
+    #[tokio::test]
+    async fn a_moments_lookup_failure_is_tried_again_soon_and_not_held_against_the_feed() {
+        let ctx = test_ctx(config::Config::default()).await;
+        let blip = "connecting: dns error: failed to lookup address information: Temporary failure in name resolution";
+        ctx.feed_failed("npr", "https://feeds.npr.org/x", blip).await.unwrap();
+        // Nothing on the feed: no error, no run of failures to back off from or call it gone by.
+        let s = ctx.db.feed_summary("npr").await.unwrap();
+        assert!(s.last_error.is_none() && s.error_since.is_none(), "{:?}", s.last_error);
+        // Due again in minutes, though a feed nobody subscribes to is otherwise read once a day.
+        let state = db::HttpState { last_checked: Some(db::now() - 2 * 86_400), ..Default::default() };
+        let due = ctx.due(&config::Config::default(), &feed(), "npr", &state, false).unwrap();
+        assert!((due - db::now() - RETRY_LOOKUP_SECS).abs() <= 2, "{due}");
+        // A real failure is the feed's.
+        ctx.feed_failed("gone", "https://x/feed", "HTTP 404 Not Found").await.unwrap();
+        assert_eq!(ctx.db.feed_summary("gone").await.unwrap().last_error.as_deref(), Some("HTTP 404 Not Found"));
+    }
+
     #[tokio::test]
     async fn a_reload_takes_the_catalogue_another_ipx_wrote() {
         let with = |id: &str| {

src/web.rs

@@ -1029,10 +1029,15 @@ struct Listed {
     items: Vec<ListedItem>,
 }
 
-/// A feed's last error as its Directory page says it: explained, or that the check failed, never
-/// the error as it stands, which can name the feed's address, and the Directory names none.
-fn failure_words(err: &str) -> String {
-    crate::feed::explain_failure(err).map_or_else(|| "Its last check failed.".to_owned(), |f| f.reason.to_owned())
+/// A feed's last error as its Directory page says it: explained once it has been failing a day, as
+/// the feed's own page does, or else that the check failed; never the error as it stands, which can
+/// name the feed's address, and the Directory names none. A day, so that a site down for an hour,
+/// or a resolver for a minute, is not called gone (#143).
+fn failure_words(err: &str, failing_for: i64) -> String {
+    Some(err)
+        .filter(|_| failing_for >= FLAG_AFTER_SECS)
+        .and_then(crate::feed::explain_failure)
+        .map_or_else(|| "Its last check failed.".to_owned(), |f| f.reason.to_owned())
 }
 
 /// A listed feed's description and latest twenty items. Only a feed the Directory lists, so a
@@ -1049,7 +1054,9 @@ async fn get_listed(
     let rows = state.ctx.db.entries_in(user.id, Some(&id), crate::db::Filter::parse("all"), None, 0, 20, &order).await?;
     let mut sanitizer = feed_sanitizer();
     let description = state.ctx.db.feed_description(&id).await?.map(|d| clean_description(&mut sanitizer, &d, None));
-    let failing = state.ctx.db.feed_summary(&id).await?.last_error.as_deref().map(failure_words);
+    let summary = state.ctx.db.feed_summary(&id).await?;
+    let failing_for = summary.error_since.map_or(0, |since| crate::db::now() - since);
+    let failing = summary.last_error.as_deref().map(|e| failure_words(e, failing_for));
     let items = rows
         .into_iter()
         .map(|e| ListedItem {
@@ -1157,10 +1164,14 @@ mod tests {
 
     #[test]
     fn a_failing_feed_says_why_in_the_directory_without_its_address() {
-        assert_eq!(failure_words("the feed's address answered with nothing at all"), "This address answers with nothing; the site may be gone.");
+        let day = FLAG_AFTER_SECS;
+        let nothing = "the feed's address answered with nothing at all";
+        assert_eq!(failure_words(nothing, day), "This address answers with nothing; the site may be gone.");
+        // Not before it has been failing a day, as on the feed's own page (#143).
+        assert_eq!(failure_words(nothing, 3600), "Its last check failed.");
         // reqwest names the URL; the Directory names none.
         let raw = "error sending request for url (http://daily-quests.com/comic/?feed=atom): connection closed";
-        assert_eq!(failure_words(raw), "Its last check failed.");
+        assert_eq!(failure_words(raw, day), "Its last check failed.");
     }
 
     #[test]

web/src/dialogs.ts

@@ -137,7 +137,7 @@ function drawDirectory(box=$('#directory'), focus?: string){
       <div class="show">${artHTML(show.image,NAME(show))}<div class="meta"><h2>${esc(NAME(show))}</h2>${
         // Its category's page is one click away from here.
         show.category?`<button type="button" class="dlink" data-go="${esc(show.category)}">${esc(show.subcategory||show.category)}</button>`:''}
-        <p class="sub">${n?`${n} ${n===1?'person here subscribes':'people here subscribe'}`:'Nobody here subscribes yet'}</p>
+        ${n?`<p class="sub">${n} ${n===1?'person here subscribes':'people here subscribe'}</p>`:''}
         <p class="sub dfail" id="dfail" hidden></p>
         <div class="acts"><button class="btn ico primary" data-a="sub" title="Subscribe" aria-label="Subscribe">${ICON.plus}</button></div></div></div>
       <div class="about" id="dabout" hidden><p></p><button type="button" class="dlink" aria-expanded="false" hidden>More</button></div>`