Add some type utils, findFeed, and fix feed listener to use limit: 0 instead of since

packages/feeds/src/controller.ts

@@ -350,12 +350,9 @@ export class FeedController {
     }
 
     return () => {
-      const since = now()
       const controller = new AbortController()
       const signal = AbortSignal.any(removeNil([controller.signal, this.options.signal]))
-      const requestFilters = filters!
-        .filter((filter: Filter) => !filter.until || filter.until <= since)
-        .map((filter: Filter) => ({...filter, since}))
+      const requestFilters = filters!.map((filter: Filter) => ({...filter, limit: 0}))
 
       requestPage(
         omitVals([undefined], {

packages/feeds/src/utils.ts

@@ -214,6 +214,20 @@ export const walkFeed = (feed: Feed, visit: (feed: Feed) => void) => {
   }
 }
 
+export const findFeed = (feed: Feed, match: (feed: Feed) => boolean): Feed | undefined => {
+  if (match(feed)) return feed
+
+  if (hasSubFeeds(feed)) {
+    for (const subFeed of getFeedArgs(feed)) {
+      const found = findFeed(subFeed, match)
+
+      if (found) {
+        return found
+      }
+    }
+  }
+}
+
 export const simplifyFeed = (feed: Feed): Feed => {
   if (isUnionFeed(feed)) {
     const args = getFeedArgs(feed)