From 795a99ae2b055895e986bcd3904cc3635cfcff97 Mon Sep 17 00:00:00 2001
From: James Brechtel <git@jamesbrechtel.com>
Date: Wed, 20 May 2026 11:54:06 -0400
Subject: [PATCH] fix: deduplicate SSE events and debounce client reload

---
 src/Roux/Html.hs   | 15 +++++++++++++--
 src/Roux/Server.hs | 13 ++++++++++++-
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/Roux/Html.hs b/src/Roux/Html.hs
index 43e59af..efd4e35 100644
--- a/src/Roux/Html.hs
+++ b/src/Roux/Html.hs
@@ -344,8 +344,13 @@ sseRecipeJs =
         , "if (!el) return;"
         , "var currentRecipe = el.textContent;"
         , "var es = new EventSource('/events');"
+        , "var lastReload = 0;"
         , "es.addEventListener('recipe-changed', function(e) {"
-        , "  if (e.data === currentRecipe) location.reload();"
+        , "  if (e.data !== currentRecipe) return;"
+        , "  var now = Date.now();"
+        , "  if (now - lastReload < 2000) return;"
+        , "  lastReload = now;"
+        , "  location.reload();"
         , "});"
         , "})();"
         ]
@@ -358,7 +363,13 @@ sseIndexJs =
         , "'use strict';"
         , "if (!window.EventSource) return;"
         , "var es = new EventSource('/events');"
-        , "es.addEventListener('recipe-changed', function() { location.reload(); });"
+        , "var lastReload = 0;"
+        , "es.addEventListener('recipe-changed', function() {"
+        , "  var now = Date.now();"
+        , "  if (now - lastReload < 2000) return;"
+        , "  lastReload = now;"
+        , "  location.reload();"
+        , "});"
         , "})();"
         ]
 
diff --git a/src/Roux/Server.hs b/src/Roux/Server.hs
index f344c30..45e0861 100644
--- a/src/Roux/Server.hs
+++ b/src/Roux/Server.hs
@@ -115,7 +115,18 @@ sseHandler changeLog _request respond = do
                     sent <- readIORef lastSent
                     when (version > sent) $ do
                         let newEntries = takeWhile (\(v, _) -> v > sent) entries
-                        forM_ newEntries $ \(_v, path) -> do
+                        -- Entries are newest-first. Deduplicate by filename,
+                        -- keeping the newest (first encountered) entry per file.
+                        let deduped =
+                                foldl'
+                                    ( \acc e@(_, p) ->
+                                        if any ((== p) . snd) acc
+                                            then acc
+                                            else e : acc
+                                    )
+                                    []
+                                    newEntries
+                        forM_ deduped $ \(_v, path) -> do
                             write
                                 ( lazyByteString $
                                     LB.fromStrict $