From ff89302cf5e39fbe3cc8213ab005f4d5a9b49a0a Mon Sep 17 00:00:00 2001
From: Benoit Marty <benoit@matrix.org>
Date: Wed, 19 Aug 2026 11:56:34 +0200
Subject: [PATCH] Normalize the applicationName used in user agent, as HTTP
 spec does not allow UTF-8 chars in headers.

---
 .../libraries/core/extensions/BasicExtensions.kt     | 12 ++++++++++++
 .../libraries/core/extensions/BasicExtensionsTest.kt |  6 ++++++
 .../network/useragent/DefaultUserAgentProvider.kt    |  5 +++--
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/libraries/core/src/main/kotlin/io/element/android/libraries/core/extensions/BasicExtensions.kt b/libraries/core/src/main/kotlin/io/element/android/libraries/core/extensions/BasicExtensions.kt
index fe563138ad..87d6350c65 100644
--- a/libraries/core/src/main/kotlin/io/element/android/libraries/core/extensions/BasicExtensions.kt
+++ b/libraries/core/src/main/kotlin/io/element/android/libraries/core/extensions/BasicExtensions.kt
@@ -8,6 +8,7 @@
 
 package io.element.android.libraries.core.extensions
 
+import java.text.Normalizer
 import java.util.Locale
 
 fun Boolean.toOnOff() = if (this) "ON" else "OFF"
@@ -114,3 +115,14 @@ fun String.toSafeLength(
         this
     }
 }
+
+/**
+ * Remove accents and replace special characters by ASCII from the string.
+ * For instance, "é" will be replaced by "e", "ç" by "c", etc.
+ */
+fun String.normalized(): String {
+    // Normalize the string.
+    return Normalizer.normalize(this, Normalizer.Form.NFD)
+        // then keep only ASCII characters and replace non-ASCII characters with an empty string.
+        .replace("[^\\p{ASCII}]".toRegex(), "")
+}
diff --git a/libraries/core/src/test/kotlin/io/element/android/libraries/core/extensions/BasicExtensionsTest.kt b/libraries/core/src/test/kotlin/io/element/android/libraries/core/extensions/BasicExtensionsTest.kt
index 0099a67a79..c3cae14843 100644
--- a/libraries/core/src/test/kotlin/io/element/android/libraries/core/extensions/BasicExtensionsTest.kt
+++ b/libraries/core/src/test/kotlin/io/element/android/libraries/core/extensions/BasicExtensionsTest.kt
@@ -74,4 +74,10 @@ class BasicExtensionsTest {
         val result = textWithDirectionOverrides.filterDirectionOverrides()
         assertEquals("123456789", result)
     }
+
+    @Test
+    fun `normalized removes accents and replace special characters from text`() {
+        assertEquals("Stefan", "Ștefan".normalized())
+        assertEquals("ca enleve etre", "ça enlève être".normalized())
+    }
 }
diff --git a/libraries/network/src/main/kotlin/io/element/android/libraries/network/useragent/DefaultUserAgentProvider.kt b/libraries/network/src/main/kotlin/io/element/android/libraries/network/useragent/DefaultUserAgentProvider.kt
index 3ecd091e0d..2a32c6d273 100644
--- a/libraries/network/src/main/kotlin/io/element/android/libraries/network/useragent/DefaultUserAgentProvider.kt
+++ b/libraries/network/src/main/kotlin/io/element/android/libraries/network/useragent/DefaultUserAgentProvider.kt
@@ -12,6 +12,7 @@ import android.os.Build
 import dev.zacsweers.metro.AppScope
 import dev.zacsweers.metro.ContributesBinding
 import dev.zacsweers.metro.SingleIn
+import io.element.android.libraries.core.extensions.normalized
 import io.element.android.libraries.core.meta.BuildMeta
 import io.element.android.libraries.matrix.api.SdkMetadata
 
@@ -26,11 +27,11 @@ class DefaultUserAgentProvider(
     override fun provide(): String = userAgent
 
     /**
-     * Create an user agent with the application version.
+     * Create a user agent with the application version.
      * Ex: Element X/1.5.0 (Xiaomi Mi 9T; Android 11; RKQ1.200826.002; Sdk c344b155c)
      */
     private fun buildUserAgent(): String {
-        val appName = buildMeta.applicationName
+        val appName = buildMeta.applicationName.normalized()
         val appVersion = buildMeta.versionName
         val deviceManufacturer = Build.MANUFACTURER
         val deviceModel = Build.MODEL