diff --git a/.claude/CLAUDE.md b/.claude/CLAUDE.md
index 7225a48c67..e0a8c7604a 100644
--- a/.claude/CLAUDE.md
+++ b/.claude/CLAUDE.md
@@ -302,6 +302,21 @@ Do this before considering the task complete.
   `forEach`/`map`/`filter`/`any` — the `fast*` variants allocate no iterator,
   no intermediate list, and no lambda object. Don't "modernize" those into
   stdlib collection calls; match the surrounding hot-path style.
+- **Never put raw invisible/bidirectional Unicode characters in source files**
+  — write them as `\uXXXX` escapes instead (`'\u202E'`, `Regex("[\u200B-\u200D\uFEFF]")`).
+  This covers the bidi family Sonar's Trojan-Source rule (CVE-2021-42574)
+  flags — U+202A–U+202E, the isolates U+2066–U+2069, U+200E/U+200F, U+061C —
+  plus zero-width characters (U+200B–U+200D, U+FEFF, U+2060). The escape
+  compiles to the identical codepoint, so behaviour is unchanged; the point is
+  that the file on disk stays visually unambiguous. Applies even when the
+  character is *intentional* (sanitizer strip-lists, adversarial test
+  payloads) — that's data, and escapes express it just as well. Exceptions:
+  U+200D as part of a real emoji ZWJ sequence in test data (👩‍👧 — functional,
+  not a bidi control), and LRM/RLM inside Crowdin-managed `strings.xml`
+  translations (legitimate RTL typography; don't touch those files by hand
+  anyway). Note the tooling trap: the Edit tool may normalise a typed
+  `\uXXXX` back into the raw character — if that happens, do the replacement
+  at byte level (`perl -CSD -pe 's/\x{202E}/\\u202E/g'`).
 
 ### Navigation Shell
 - **Desktop**: Sidebar + main content area
diff --git a/amethyst/src/test/java/com/vitorpamplona/amethyst/service/uploads/blossom/BlossomPaymentSafetyTest.kt b/amethyst/src/test/java/com/vitorpamplona/amethyst/service/uploads/blossom/BlossomPaymentSafetyTest.kt
index d1564aeac8..fbaed1939b 100644
--- a/amethyst/src/test/java/com/vitorpamplona/amethyst/service/uploads/blossom/BlossomPaymentSafetyTest.kt
+++ b/amethyst/src/test/java/com/vitorpamplona/amethyst/service/uploads/blossom/BlossomPaymentSafetyTest.kt
@@ -215,9 +215,9 @@ class BlossomPaymentSafetyTest {
 
     @Test
     fun reasonBidiOverridesAreRemoved() {
-        val clean = challenge(invoice1000Sats, reason = "fee ‮reversed‬ text").sanitizedReason()!!
-        assertFalse(clean.contains('‮'))
-        assertFalse(clean.contains('‬'))
+        val clean = challenge(invoice1000Sats, reason = "fee \u202Ereversed\u202C text").sanitizedReason()!!
+        assertFalse(clean.contains('\u202E'))
+        assertFalse(clean.contains('\u202C'))
     }
 
     @Test
diff --git a/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/moderation/notifications/Sanitizer.kt b/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/moderation/notifications/Sanitizer.kt
index d2fd4927fc..bd6cc3098b 100644
--- a/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/moderation/notifications/Sanitizer.kt
+++ b/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/moderation/notifications/Sanitizer.kt
@@ -21,8 +21,8 @@
 package com.vitorpamplona.amethyst.commons.moderation.notifications
 
 private val CONTROL_CHARS = Regex("\\p{Cntrl}")
-private val RTL_OVERRIDES = Regex("[‪-‮⁦-⁩]")
-private val ZERO_WIDTH = Regex("[​-‍]")
+private val RTL_OVERRIDES = Regex("[\u202A-\u202E\u2066-\u2069]")
+private val ZERO_WIDTH = Regex("[\u200B-\u200D\uFEFF]")
 private val WHITESPACE = Regex("\\s+")
 private val URL_PATTERN = Regex("https?://\\S+")
 
diff --git a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nipB7Blossom/BlossomPaymentRequired.kt b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nipB7Blossom/BlossomPaymentRequired.kt
index 6ffd47cb8c..d1adbc8938 100644
--- a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nipB7Blossom/BlossomPaymentRequired.kt
+++ b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nipB7Blossom/BlossomPaymentRequired.kt
@@ -74,7 +74,7 @@ data class BlossomPaymentRequired(
         const val MAX_REASON_LENGTH = 200
 
         /** LRE/RLE/PDF/LRO/RLO and the isolate family — invisible, and they reorder what follows. */
-        private val BIDI_OVERRIDES = charArrayOf('‪', '‫', '‬', '‭', '‮', '⁦', '⁧', '⁨', '⁩', '‏', '‎')
+        private val BIDI_OVERRIDES = charArrayOf('\u202A', '\u202B', '\u202C', '\u202D', '\u202E', '\u2066', '\u2067', '\u2068', '\u2069', '\u200F', '\u200E')
 
         private val WHITESPACE_RUN = Regex("\\s+")