From 87afa23cad077c09bc1eb743800ae3396b531146 Mon Sep 17 00:00:00 2001
From: Brendan Osborne <brendan.r.osborne@gmail.com>
Date: Mon, 2 Jun 2025 13:22:06 +1000
Subject: [PATCH] feat(updater): add allowDowngrades option (#2726)

* feat(updater): add allowDowngrades option

* Add change file for allow_downgrades feature

* Update .changes/add-allow-downgrades.md
---
 .changes/add-allow-downgrades.md  | 8 ++++++++
 plugins/updater/guest-js/index.ts | 4 ++++
 plugins/updater/src/commands.rs   | 4 ++++
 3 files changed, 16 insertions(+)
 create mode 100644 .changes/add-allow-downgrades.md

diff --git a/.changes/add-allow-downgrades.md b/.changes/add-allow-downgrades.md
new file mode 100644
index 000000000..dd888671f
--- /dev/null
+++ b/.changes/add-allow-downgrades.md
@@ -0,0 +1,8 @@
+---
+"updater": minor
+"updater-js": minor
+---
+
+Add allowDowngrades parameter to check command
+
+Added a new optional `allowDowngrades` parameter to the JavaScript check command that allows the updater to consider versions that are lower than the current version as valid updates. When enabled, the version comparator will accept any version that is different from the current version, effectively allowing downgrades.
diff --git a/plugins/updater/guest-js/index.ts b/plugins/updater/guest-js/index.ts
index 87f7929a2..c33033ecf 100644
--- a/plugins/updater/guest-js/index.ts
+++ b/plugins/updater/guest-js/index.ts
@@ -22,6 +22,10 @@ interface CheckOptions {
    * Target identifier for the running application. This is sent to the backend.
    */
   target?: string
+  /**
+   * Allow downgrades to previous versions by not checking if the current version is greater than the available version.
+   */
+  allowDowngrades?: boolean
 }
 
 /** Options used when downloading an update */
diff --git a/plugins/updater/src/commands.rs b/plugins/updater/src/commands.rs
index ae84294f7..129c413c2 100644
--- a/plugins/updater/src/commands.rs
+++ b/plugins/updater/src/commands.rs
@@ -46,6 +46,7 @@ pub(crate) async fn check<R: Runtime>(
     timeout: Option<u64>,
     proxy: Option<String>,
     target: Option<String>,
+    allow_downgrades: Option<bool>,
 ) -> Result<Option<Metadata>> {
     let mut builder = webview.updater_builder();
     if let Some(headers) = headers {
@@ -63,6 +64,9 @@ pub(crate) async fn check<R: Runtime>(
     if let Some(target) = target {
         builder = builder.target(target);
     }
+    if allow_downgrades.unwrap_or(false) {
+        builder = builder.version_comparator(|current, update| update.version != current);
+    }
 
     let updater = builder.build()?;
     let update = updater.check().await?;