From 74056a0a1f105d70c606e356bb46569c73016589 Mon Sep 17 00:00:00 2001
From: Alexey <1556417+alex-solovyev@users.noreply.github.com>
Date: Sat, 14 Mar 2026 08:18:23 +0100
Subject: [PATCH] fix(t3219): address CodeRabbit review feedback on
 prompt-guard patterns

- Move _PG_YAML_PATTERNS_LOADED flag assignment to after successful
  parse+cache in _pg_load_yaml_patterns(); previously set after file
  discovery but before parsing, so a parse failure would permanently
  disable YAML loading on subsequent calls (transient failures treated
  as permanent)
- Replace byte-level \xNN hex escapes in zero-width character YAML
  pattern with literal Unicode chars (U+200B ZWSP, U+200C ZWNJ,
  U+200D ZWJ, U+FEFF BOM) for portability across rg/grep/ggrep;
  byte-level escapes match individual bytes, not multi-byte UTF-8
  codepoints

Closes #3219
---
 .agents/configs/prompt-injection-patterns.yaml | 5 ++++-
 .agents/scripts/prompt-guard-helper.sh         | 8 +++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/.agents/configs/prompt-injection-patterns.yaml b/.agents/configs/prompt-injection-patterns.yaml
index 089db59ad..c1a20728b 100644
--- a/.agents/configs/prompt-injection-patterns.yaml
+++ b/.agents/configs/prompt-injection-patterns.yaml
@@ -516,7 +516,10 @@ context_manipulation:
 
   - severity: LOW
     description: "Zero-width characters"
-    pattern: '[\xE2\x80\x8B\xE2\x80\x8C\xE2\x80\x8D\xEF\xBB\xBF]'
+    # Literal Unicode chars (U+200B ZWSP, U+200C ZWNJ, U+200D ZWJ, U+FEFF BOM)
+    # for portability across rg/grep/ggrep — byte-level \xNN escapes match
+    # individual bytes, not multi-byte UTF-8 codepoints.
+    pattern: '[​‌‍]'
 
   # --- Lasso net-new: False authority claims ---
   - severity: HIGH
diff --git a/.agents/scripts/prompt-guard-helper.sh b/.agents/scripts/prompt-guard-helper.sh
index 107e7c6ff..802c26518 100755
--- a/.agents/scripts/prompt-guard-helper.sh
+++ b/.agents/scripts/prompt-guard-helper.sh
@@ -168,10 +168,6 @@ _pg_load_yaml_patterns() {
 		return 1
 	}
 
-	# Only mark loaded after successful file discovery (prevents transient failures
-	# from permanently disabling YAML loading on subsequent calls)
-	_PG_YAML_PATTERNS_LOADED="true"
-
 	local patterns=""
 	local current_category=""
 	local severity="" description="" pattern=""
@@ -228,8 +224,10 @@ _pg_load_yaml_patterns() {
 		return 1
 	fi
 
-	# Cache for subsequent calls
+	# Cache for subsequent calls — mark loaded only after successful parse+cache
+	# so transient parse failures do not permanently disable YAML loading.
 	_PG_YAML_PATTERNS_CACHE="$patterns"
+	_PG_YAML_PATTERNS_LOADED="true"
 
 	# Remove trailing newline
 	echo "${patterns%$'\n'}"