From b93808235c058c1f2ed422a713f4f97cf09389ab Mon Sep 17 00:00:00 2001
From: Rosa Gutierrez <rosa@37signals.com>
Date: Thu, 5 Feb 2026 21:15:22 +0100
Subject: [PATCH] Limit cached entry sizes

1MB and no limit for number of entries except for attachments, where we
limit individual entries to 2MB and total of entries to 500. The number
is based on the following percentiles for Active Storage blobs:

```
p50: 97.1044921875 KB
p75: 236.9140625 KB
p90: 917.7548828125 KB
```
---
 app/views/pwa/service_worker.js.erb | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/app/views/pwa/service_worker.js.erb b/app/views/pwa/service_worker.js.erb
index cfdf5468f..84f274673 100644
--- a/app/views/pwa/service_worker.js.erb
+++ b/app/views/pwa/service_worker.js.erb
@@ -9,7 +9,8 @@ TurboOffline.addRule({
     cacheName: "main",
     maxAge: 60 * 60 * 24 * 3,
     networkTimeout: 3,
-    fetchOptions: { cache: "no-cache" }
+    fetchOptions: { cache: "no-cache" },
+    maxEntrySize: 1024 * 1024
   })
 })
 
@@ -17,7 +18,8 @@ TurboOffline.addRule({
   match: /\/assets\/.+[-\.][0-9a-f]+\.(js|css|svg|png|jpg|webp|woff2?|ico)$/,
   handler: TurboOffline.handlers.cacheFirst({
     cacheName: "assets",
-    maxAge: 60 * 60 * 24 * 7
+    maxAge: 60 * 60 * 24 * 7,
+    maxEntrySize: 1024 * 1024
   })
 })
 
@@ -27,7 +29,8 @@ TurboOffline.addRule({
   handler: TurboOffline.handlers.networkFirst({
     cacheName: "main",
     maxAge: 60 * 60 * 24 * 3,
-    networkTimeout: 2
+    networkTimeout: 2,
+    maxEntrySize: 1024 * 1024
   })
 })
 
@@ -36,7 +39,9 @@ TurboOffline.addRule({
   handler: TurboOffline.handlers.networkFirst({
     cacheName: "storage",
     maxAge: 60 * 60 * 24 * 7,
-    networkTimeout: 2
+    networkTimeout: 2,
+    maxEntrySize: 2 * 1024 * 1024, // 2MB covers about 95% of all Fizzy blobs
+    maxEntries: 500
   })
 })
 
@@ -45,7 +50,8 @@ TurboOffline.addRule({
   handler: TurboOffline.handlers.networkFirst({
     cacheName: "main",
     maxAge: 60 * 60 * 24,
-    networkTimeout: 3
+    networkTimeout: 3,
+    maxEntrySize: 1024 * 1024
   })
 })