Apple Podcasts' top charts into the directory weekly, and its categories checked (#252)

With apple_country set, the directory fetches Apple's top 100 podcasts and the top 50 of each of
its 19 categories for that country (itunes.apple.com/{cc}/rss/toppodcasts), looks up each
show's RSS address (/lookup, 100 ids a call, three seconds apart, as Apple asks for no more than
about twenty a minute), and stores them as the snapshot apple-podcasts with no subscribers. The
refresher fetches them like any feed; the most-subscribed chart is unchanged. Apple's primary
genre goes in as the snapshot's category, used only while a feed names none.

The same weekly run reads Apple's genre tree (ws/genres?id=26) and warns when it differs from
ipx_feed's CATEGORIES; on 2026-10-15 they were the same, all 19 and their subcategories.

A syncs table keeps when it last ran: at start if a week has passed, again weekly, an hour after
a failure. keep_instances spares apple-podcasts, which no token holds, and no token may take
the name. A trace a sync, a span each answer.

CLAUDE.md: builds one cargo command at a time, the load looked at before and after, after a
build chained with a test compile took Tower past 200.

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

crates/directory/src/store.rs

@@ -84,6 +84,11 @@ const SCHEMA: &[&str] = &[
         PRIMARY KEY (instance, feed_id)
     )",
     "CREATE INDEX IF NOT EXISTS snapshots_feed ON snapshots (feed_id)",
+    // When each periodic job last finished: Apple's weekly sync (#252).
+    "CREATE TABLE IF NOT EXISTS syncs (
+        name TEXT PRIMARY KEY,
+        at BIGINT NOT NULL
+    )",
     "CREATE TABLE IF NOT EXISTS blocked (
         id TEXT PRIMARY KEY,
         url TEXT,
@@ -164,6 +169,23 @@ impl Store {
         Ok(self.db.query_all_raw(self.stmt(sql, values)).await?)
     }
 
+    /// When the job `name` last finished, Unix seconds.
+    pub async fn synced_at(&self, name: &str) -> Result<Option<i64>> {
+        Ok(match self.rows("SELECT at FROM syncs WHERE name = $1", vec![name.into()]).await?.first() {
+            Some(r) => Some(r.try_get("", "at")?),
+            None => None,
+        })
+    }
+
+    pub async fn set_synced(&self, name: &str, at: i64) -> Result<()> {
+        self.exec(
+            "INSERT INTO syncs (name, at) VALUES ($1, $2) ON CONFLICT (name) DO UPDATE SET at = excluded.at",
+            vec![name.into(), at.into()],
+        )
+        .await?;
+        Ok(())
+    }
+
     pub async fn ping(&self) -> Result<()> {
         self.rows("SELECT 1", vec![]).await?;
         Ok(())
@@ -241,7 +263,8 @@ impl Store {
             .iter()
             .map(|r| r.try_get("", "instance"))
             .collect::<Result<_, _>>()?;
-        for name in present.iter().filter(|n| !names.contains(n)) {
+        // Apple's charts are no token's, and stay until the next sync replaces them.
+        for name in present.iter().filter(|n| !names.contains(n) && n.as_str() != crate::apple::INSTANCE) {
             dropped += self.drop_instance(name).await?;
         }
         Ok(dropped)