From b4fd252c203953ab3f2724fe5e49c86bc221db94 Mon Sep 17 00:00:00 2001
From: ibstellar <151468788+aregmii@users.noreply.github.com>
Date: Sat, 16 May 2026 23:23:54 -0400
Subject: [PATCH] perf (prompt_injection): cache classifier behind Lazy<> (was
 Box-alloc per call) (#1962)

---
 src/openhuman/prompt_injection/detector.rs | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/openhuman/prompt_injection/detector.rs b/src/openhuman/prompt_injection/detector.rs
index 71460fb10..e27a3f2ae 100644
--- a/src/openhuman/prompt_injection/detector.rs
+++ b/src/openhuman/prompt_injection/detector.rs
@@ -174,14 +174,24 @@ static DETECTION_RULES: Lazy<Vec<DetectionRule>> = Lazy::new(|| {
     ]
 });
 
-fn optional_classifier() -> Option<Box<dyn OptionalClassifier>> {
+static OPTIONAL_CLASSIFIER: Lazy<Option<Box<dyn OptionalClassifier>>> = Lazy::new(|| {
     let choice = env::var("OPENHUMAN_PROMPT_INJECTION_CLASSIFIER")
         .unwrap_or_else(|_| "off".to_string())
         .to_ascii_lowercase();
-    match choice.as_str() {
+    let classifier: Option<Box<dyn OptionalClassifier>> = match choice.as_str() {
         "heuristic" => Some(Box::new(HeuristicClassifier)),
         _ => None,
-    }
+    };
+    tracing::debug!(
+        "[prompt_injection] optional classifier resolved choice={:?} active={}",
+        choice,
+        classifier.is_some()
+    );
+    classifier
+});
+
+fn optional_classifier() -> Option<&'static dyn OptionalClassifier> {
+    OPTIONAL_CLASSIFIER.as_deref()
 }
 
 fn normalize_prompt(input: &str) -> NormalizedPrompt {