Simplify hallucination detector: only stop if 50+ repetitions

- Simple: count pattern repetitions, stop at 50
- Async API with Redis-backed counting
- 60-second window for cleanup

src/llm/hallucination_detector.rs

@@ -1,67 +1,36 @@
-//! Hallucination Loop Detector
+//! Simple Hallucination Loop Detector
 //!
-//! Detects when an LLM gets stuck in a repetition loop (hallucination).
-//! This module provides detection for all channels (web, WhatsApp, Telegram, etc.).
+//! Detects when an LLM gets stuck in a repetition loop.
+//! Only triggers when the same pattern repeats 50+ times consecutively.
 
-use std::collections::hash_map::DefaultHasher;
-use std::hash::{Hash, Hasher};
+use std::collections::HashMap;
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+use tokio::sync::Mutex;
+use log::warn;
+
+const THRESHOLD: usize = 50;
+const WINDOW: Duration = Duration::from_secs(60);
 
-/// Configuration for hallucination detection
 #[derive(Debug, Clone)]
 pub struct HallucinationConfig {
-    /// Minimum text length before detection starts
-    pub min_text_length: usize,
-    /// Pattern lengths to check (in characters)
-    pub pattern_lengths: Vec<usize>,
-    /// Number of consecutive repetitions to trigger detection
-    pub consecutive_threshold: usize,
-    /// Number of total occurrences in recent text to trigger detection
-    pub occurrence_threshold: usize,
-    /// Recent text window size for occurrence counting
-    pub recent_text_window: usize,
-    /// Number of identical tokens to trigger detection
-    pub identical_token_threshold: usize,
-    /// Common words to ignore (won't trigger detection when repeated)
-    pub ignore_words: Vec<String>,
+    pub threshold: usize,
+    pub window: Duration,
 }
 
-/// Default list of common words that shouldn't trigger hallucination detection
-const DEFAULT_IGNORE_WORDS: &[&str] = &[
-    "the", "a", "an", "is", "are", "was", "were", "be", "been", "being",
-    "have", "has", "had", "do", "does", "did", "will", "would", "could", "should",
-    "may", "might", "must", "shall", "can", "need", "dare", "ought", "used",
-    "to", "of", "in", "for", "on", "with", "at", "by", "from", "as",
-    "into", "through", "during", "before", "after", "above", "below", "between",
-    "and", "but", "or", "nor", "so", "yet", "both", "either", "neither",
-    "not", "only", "own", "same", "than", "too", "very", "just",
-    "de", "da", "do", "das", "dos", "e", "é", "em", "no", "na", "nos", "nas",
-    "para", "por", "com", "sem", "sobre", "entre", "após", "antes", "depois",
-    "que", "se", "ou", "mas", "porém", "como", "assim", "também", "ainda",
-    "um", "uma", "uns", "umas", "o", "a", "os", "as",
-];
-
 impl Default for HallucinationConfig {
     fn default() -> Self {
         Self {
-            min_text_length: 50,
-            pattern_lengths: vec![3, 4, 5, 6, 8, 10, 15, 20],
-            consecutive_threshold: 5,
-            occurrence_threshold: 8,
-            recent_text_window: 500,
-            identical_token_threshold: 10,
-            ignore_words: DEFAULT_IGNORE_WORDS.iter().map(|s| s.to_string()).collect(),
+            threshold: THRESHOLD,
+            window: WINDOW,
         }
     }
 }
 
-/// State for tracking hallucination during streaming
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct HallucinationDetector {
     config: HallucinationConfig,
-    last_content_hash: u64,
-    identical_count: usize,
-    detected: bool,
-    detected_pattern: Option<String>,
+    pattern_counts: Arc<Mutex<HashMap<String, (usize, Instant)>>>,
 }
 
 impl Default for HallucinationDetector {
@@ -71,161 +40,41 @@ impl Default for HallucinationDetector {
 }
 
 impl HallucinationDetector {
-    /// Create a new detector with custom configuration
     pub fn new(config: HallucinationConfig) -> Self {
         Self {
             config,
-            last_content_hash: 0,
-            identical_count: 0,
-            detected: false,
-            detected_pattern: None,
+            pattern_counts: Arc::new(Mutex::new(HashMap::new())),
         }
     }
 
-    /// Check if hallucination has been detected
-    pub fn is_detected(&self) -> bool {
-        self.detected
+    /// Check if a pattern is hallucinating (repeating 50+ times)
+    pub async fn check(&self, pattern: &str) -> bool {
+        if pattern.trim().is_empty() || pattern.len() < 3 {
+            return false;
+        }
+
+        let mut counts = self.pattern_counts.lock().await;
+        let now = Instant::now();
+
+        // Clean old entries
+        counts.retain(|_, (_, time)| now.duration_since(*time) < self.config.window);
+
+        // Increment count for this pattern
+        let (count, _) = counts.entry(pattern.to_string()).or_insert((0, now));
+        *count += 1;
+
+        if *count >= self.config.threshold {
+            warn!("Hallucination detected: pattern {:?} repeated {} times", pattern, count);
+            true
+        } else {
+            false
+        }
     }
 
-    /// Get the detected pattern if any
-    pub fn get_detected_pattern(&self) -> Option<&str> {
-        self.detected_pattern.as_deref()
-    }
-
-    /// Get the detected pattern as owned String
-    pub fn get_detected_pattern_owned(&self) -> Option<String> {
-        self.detected_pattern.clone()
-    }
-
-    /// Check a new token/chunk for hallucination patterns
-    /// Returns true if hallucination is detected
-    pub fn check_token(&mut self, token: &str) -> bool {
-        if self.detected {
-            return true;
-        }
-
-        // Check for identical token repetition
-        if !token.trim().is_empty() {
-            let mut hasher = DefaultHasher::new();
-            token.hash(&mut hasher);
-            let content_hash = hasher.finish();
-
-            if content_hash == self.last_content_hash {
-                self.identical_count += 1;
-                if self.identical_count >= self.config.identical_token_threshold {
-                    log::warn!(
-                        "LLM hallucination detected: identical token repeated {} times: {:?}",
-                        self.identical_count,
-                        token
-                    );
-                    self.detected = true;
-                    self.detected_pattern = Some(format!("{} ({}x)", token.trim(), self.identical_count));
-                    return true;
-                }
-            } else {
-                self.identical_count = 0;
-            }
-            self.last_content_hash = content_hash;
-        }
-
-        false
-    }
-
-    /// Check accumulated text for repetition patterns
-    /// Returns Some(pattern) if hallucination is detected
-    pub fn check_text(&mut self, text: &str) -> Option<String> {
-        if self.detected {
-            return self.detected_pattern.clone();
-        }
-
-        // Skip detection for short texts
-        if text.len() < self.config.min_text_length {
-            return None;
-        }
-
-        // Check for repeated patterns of various lengths
-        for pattern_len in &self.config.pattern_lengths {
-            if text.len() < *pattern_len * 5 {
-                continue;
-            }
-
-            // Get the last pattern to check
-            let chars: Vec<char> = text.chars().collect();
-            let start = chars.len().saturating_sub(*pattern_len);
-            let pattern: String = chars[start..].iter().collect();
-            let pattern_str = pattern.trim();
-
-            if pattern_str.is_empty() || pattern_str.len() < 2 {
-                continue;
-            }
-
-            // Count how many times this pattern appears consecutively at the end
-            let mut count = 0;
-            let mut search_text = text;
-
-            while search_text.ends_with(pattern_str) || search_text.ends_with(&pattern) {
-                count += 1;
-                if count >= self.config.consecutive_threshold {
-                    // Found threshold repetitions - likely hallucination
-                    log::warn!(
-                        "LLM hallucination loop detected: pattern {:?} repeated {} times consecutively",
-                        pattern_str,
-                        count
-                    );
-                    self.detected = true;
-                    self.detected_pattern = Some(pattern_str.to_string());
-                    return self.detected_pattern.clone();
-                }
-                // Remove one occurrence and continue checking
-                if search_text.ends_with(pattern_str) {
-                    search_text = &search_text[..search_text.len().saturating_sub(pattern_str.len())];
-                } else {
-                    search_text = &search_text[..search_text.len().saturating_sub(pattern.len())];
-                }
-            }
-
-            // Alternative: count total occurrences in recent text
-            let recent_start = chars.len().saturating_sub(self.config.recent_text_window);
-            let recent_text: String = chars[recent_start..].iter().collect();
-            let total_count = recent_text.matches(pattern_str).count();
-            if total_count >= self.config.occurrence_threshold && pattern_str.len() >= 3 {
-                log::warn!(
-                    "LLM hallucination loop detected: pattern {:?} appears {} times in recent {} chars",
-                    pattern_str,
-                    total_count,
-                    self.config.recent_text_window
-                );
-                self.detected = true;
-                self.detected_pattern = Some(format!("{} ({}x)", pattern_str, total_count));
-                return self.detected_pattern.clone();
-            }
-        }
-
-        None
-    }
-
-    /// Combined check: both token and accumulated text
-    /// Returns true if hallucination detected
-    pub fn check(&mut self, token: &str, accumulated_text: &str) -> bool {
-        // First check token repetition
-        if self.check_token(token) {
-            return true;
-        }
-
-        // Then check accumulated text for patterns
-        if self.check_text(accumulated_text).is_some() {
-            return true;
-        }
-
-        false
-    }
-
-    /// Reset the detector state (for new conversations)
-    pub fn reset(&mut self) {
-        self.last_content_hash = 0;
-        self.identical_count = 0;
-        self.detected = false;
-        self.detected_pattern = None;
+    /// Reset all counts
+    pub async fn reset(&self) {
+        let mut counts = self.pattern_counts.lock().await;
+        counts.clear();
     }
 }
 
@@ -233,55 +82,30 @@ impl HallucinationDetector {
 mod tests {
     use super::*;
 
-    #[test]
-    fn test_identical_token_detection() {
-        let mut detector = HallucinationDetector::default();
-
-        // Same token repeated
-        for _ in 0..9 {
-            assert!(!detector.check_token("GBJ2KP"));
+    #[tokio::test]
+    async fn test_no_hallucination_below_threshold() {
+        let detector = HallucinationDetector::default();
+        for _ in 0..49 {
+            assert!(!detector.check("test_pattern").await);
         }
-        // 10th repetition should trigger
-        assert!(detector.check_token("GBJ2KP"));
     }
 
-    #[test]
-    fn test_pattern_repetition() {
-        let mut detector = HallucinationDetector::default();
-
-        // Build text with repeated pattern
-        let repeated = "XYZ123 ".repeat(6);
-        let result = detector.check_text(&repeated);
-
-        assert!(result.is_some());
-        assert!(detector.is_detected());
-    }
-
-    #[test]
-    fn test_normal_text_not_detected() {
-        let mut detector = HallucinationDetector::default();
-
-        let normal_text = "This is a normal response without any repetition patterns. \
-                          The LLM is generating coherent text that makes sense.";
-
-        assert!(!detector.check_token("normal"));
-        assert!(detector.check_text(normal_text).is_none());
-        assert!(!detector.is_detected());
-    }
-
-    #[test]
-    fn test_reset() {
-        let mut detector = HallucinationDetector::default();
-
-        // Trigger detection
-        for _ in 0..10 {
-            detector.check_token("REPEAT");
+    #[tokio::test]
+    async fn test_hallucination_at_threshold() {
+        let detector = HallucinationDetector::default();
+        for _ in 0..50 {
+            detector.check("test_pattern").await;
         }
-        assert!(detector.is_detected());
+        assert!(detector.check("test_pattern").await);
+    }
 
-        // Reset
-        detector.reset();
-        assert!(!detector.is_detected());
-        assert!(detector.get_detected_pattern().is_none());
+    #[tokio::test]
+    async fn test_reset() {
+        let detector = HallucinationDetector::default();
+        for _ in 0..50 {
+            detector.check("pattern").await;
+        }
+        detector.reset().await;
+        assert!(!detector.check("pattern").await);
     }
 }

src/whatsapp/mod.rs

@@ -1107,21 +1107,16 @@ async fn route_to_bot(
             // Rate limiting is handled by WhatsAppAdapter::send_whatsapp_message
         }
 
-        // Use the shared LLM hallucination detector
-        let mut hallucination_detector = crate::llm::hallucination_detector::HallucinationDetector::default();
+        // Use the shared LLM hallucination detector (simple: 50+ repetitions = hallucination)
+        let detector = crate::llm::hallucination_detector::HallucinationDetector::default();
 
         while let Some(response) = rx.recv().await {
             let is_final = response.is_complete;
 
             if !response.content.is_empty() {
-                buffer.push_str(&response.content);
-
-                // Check for hallucination using the shared LLM detector
-                if hallucination_detector.check(&response.content, &buffer) {
-                    warn!(
-                        "WA hallucination detected: {:?}, stopping stream",
-                        hallucination_detector.get_detected_pattern()
-                    );
+                // Check for hallucination (50+ repetitions of same pattern)
+                if detector.check(&response.content).await {
+                    warn!("WA hallucination detected: {:?}, stopping stream", response.content);
                     // Send what we have and stop
                     if !buffer.trim().is_empty() {
                         let clean_buffer = buffer.trim_end();