fix(card-browser): render code blocks in error messages

AnkiDroid/src/main/java/com/ichi2/anki/CoroutineHelpers.kt

@@ -51,6 +51,7 @@ import com.ichi2.anki.pages.DeckOptionsDestination
 import com.ichi2.anki.snackbar.showSnackbar
 import com.ichi2.anki.utils.openUrl
 import com.ichi2.utils.create
+import com.ichi2.utils.formatErrorMessage
 import com.ichi2.utils.message
 import com.ichi2.utils.neutralButton
 import com.ichi2.utils.positiveButton
@@ -287,7 +288,7 @@ fun Context.showError(
             .Builder(this)
             .create {
                 title(R.string.vague_error)
-                message(text = message)
+                message(text = formatErrorMessage(message))
                 positiveButton(R.string.dialog_ok)
                 if (crashReportData?.helpAction != null) {
                     neutralButton(R.string.help)

AnkiDroid/src/main/java/com/ichi2/utils/ErrorMessageFormatter.kt

@@ -0,0 +1,37 @@
+// SPDX-FileCopyrightText: 2026 Aryan Jaiswal <aryanjaiswal123123@gmail.com>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package com.ichi2.utils
+
+import android.text.Spannable
+import android.text.SpannableStringBuilder
+import android.text.style.TypefaceSpan
+
+private val PRE_TAG_REGEX = Regex("<pre>(.*?)</pre>", RegexOption.DOT_MATCHES_ALL)
+
+/**
+ * Renders `<pre>...</pre>` blocks from backend error messages as monospaced
+ * text instead of leaking the raw markup to the user.
+ */
+fun formatErrorMessage(message: String): CharSequence {
+    val matches = PRE_TAG_REGEX.findAll(message).toList()
+    if (matches.isEmpty()) return message
+
+    val builder = SpannableStringBuilder()
+    var cursor = 0
+    for (match in matches) {
+        builder.append(message, cursor, match.range.first)
+
+        val codeStart = builder.length
+        builder.append(match.groupValues[1])
+        val codeEnd = builder.length
+
+        builder.setSpan(TypefaceSpan("monospace"), codeStart, codeEnd, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
+
+        cursor = match.range.last + 1
+    }
+    if (cursor < message.length) {
+        builder.append(message, cursor, message.length)
+    }
+    return builder
+}

AnkiDroid/src/test/java/com/ichi2/utils/ErrorMessageFormatterTest.kt

@@ -0,0 +1,44 @@
+// SPDX-FileCopyrightText: 2026 Aryan Jaiswal <aryanjaiswal123123@gmail.com>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package com.ichi2.utils
+
+import android.text.Spanned
+import android.text.style.TypefaceSpan
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.ichi2.anki.EmptyApplicationCategory
+import com.ichi2.testutils.EmptyApplication
+import org.hamcrest.MatcherAssert.assertThat
+import org.hamcrest.Matchers.containsString
+import org.hamcrest.Matchers.equalTo
+import org.hamcrest.Matchers.not
+import org.junit.Test
+import org.junit.experimental.categories.Category
+import org.junit.runner.RunWith
+import org.robolectric.annotation.Config
+
+@RunWith(AndroidJUnit4::class)
+@Config(application = EmptyApplication::class)
+@Category(EmptyApplicationCategory::class)
+class ErrorMessageFormatterTest {
+    @Test
+    fun `plain message is returned unchanged`() {
+        val input = "Invalid search: an `and` was found but it is not connecting two search terms."
+        assertThat(formatErrorMessage(input).toString(), equalTo(input))
+    }
+
+    @Test
+    fun `pre tags are replaced with a monospace span`() {
+        val input = "<pre>regex parse error:\n    (?i)i[\n        ^\nerror: unclosed character class</pre>"
+
+        val output = formatErrorMessage(input) as Spanned
+
+        assertThat(output.toString(), not(containsString("<pre>")))
+        assertThat(output.toString(), not(containsString("</pre>")))
+        assertThat(output.toString(), equalTo("regex parse error:\n    (?i)i[\n        ^\nerror: unclosed character class"))
+
+        val typefaceSpans = output.getSpans(0, output.length, TypefaceSpan::class.java)
+        assertThat(typefaceSpans.size, equalTo(1))
+        assertThat(typefaceSpans[0].family, equalTo("monospace"))
+    }
+}