The refresh buttons keep turning between one feed and the next (#231)

A scan checks its feeds one at a time; in the gap between two the body class came off, the
icon snapped back upright and the spin restarted, many times a second with fetches ahead.
The class now comes off only after 600 ms with nothing being checked.

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

web/CHANGELOG.md

@@ -11,6 +11,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- The check-every-feed button turns smoothly through a scan instead of jerking back upright between one feed and the next (#231).
+
 ## [1.0.1] - 2026-10-13
 
 ### Fixed

web/src/feeds.ts

@@ -51,8 +51,17 @@ function paintScanning(){
   // The refresh buttons turn while what they check is being checked (#78). On <body>, because
   // a feed's page is redrawn as its items come in and would take a class on the button with it.
   const busy=id=>scanning.has(id)||S.feeds.some(c=>c.group===id&&scanning.has(c.id));
-  document.body.classList.toggle('scan-this',busy(S.feed));
+  spin('scan-this',busy(S.feed));
-  document.body.classList.toggle('scan-any',S.feeds.some(f=>scanning.has(f.id)));
+  spin('scan-any',S.feeds.some(f=>scanning.has(f.id)));
+}
+/// Starts a refresh button turning at once, and stops it only after a moment with nothing being
+/// checked: a scan takes its feeds one at a time, and in the gap between two the class came off,
+/// the icon snapped back upright and started again, many times a second.
+const spinStop: Record<string, number>={};
+function spin(cls: string, on: boolean){
+  clearTimeout(spinStop[cls]);
+  if(on) document.body.classList.add(cls);
+  else spinStop[cls]=setTimeout(()=>document.body.classList.remove(cls),600);
 }
 
 function renderFeeds(){