feat: implement WhatsApp bursting rate limit and consume activation tokens

src/basic/keywords/on_change.rs

@@ -176,6 +176,7 @@ pub fn fetch_folder_changes(
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::path::Path;
 
     fn apply_filters(events: Vec<FolderChangeEvent>, filters: &Option<FileFilters>) -> Vec<FolderChangeEvent> {
         let Some(ref filters) = filters else {

src/core/bot/channels/whatsapp_queue.rs

@@ -1,7 +1,8 @@
 //! WhatsApp Message Queue
 //!
-//! Implements a Redis-backed queue for WhatsApp messages to enforce
-//! Meta's official rate limits: 1 message per 6 seconds per recipient.
+//! Enforces Meta's bursting rules (up to 45 msgs in a burst window) and 
+//! handles cooling off (steady state 1 msg/6s) and rate limit errors (131056)
+//! with exponential backoff 4^X.
 
 use log::{error, info, warn};
 use redis::AsyncCommands;
@@ -26,8 +27,9 @@ pub struct WhatsAppMessageQueue {
 
 impl WhatsAppMessageQueue {
     const QUEUE_KEY: &'static str = "whatsapp:message_queue";
-    const LAST_SENT_PREFIX: &'static str = "whatsapp:last_sent:";
-    const MIN_DELAY_SECS: i64 = 6;
+    const TFT_PREFIX: &'static str = "whatsapp:tft:"; // Theoretical Finish Time
+    const BURST_CAPACITY: i64 = 45;
+    const RATE_SECS: i64 = 6;
 
     pub fn new(redis_url: &str) -> Result<Self, redis::RedisError> {
         Ok(Self {
@@ -45,7 +47,7 @@ impl WhatsAppMessageQueue {
     }
 
     pub async fn start_worker(self: Arc<Self>) {
-        info!("WhatsApp queue worker started (Meta rate: 1 msg/6s per recipient)");
+        info!("WhatsApp queue worker started (Burst: up to 45 msgs in 6s per recipient)");
         loop {
             if let Err(e) = self.process_next().await {
                 error!("WhatsApp queue worker error: {}", e);
@@ -57,38 +59,32 @@ impl WhatsAppMessageQueue {
     async fn process_next(&self) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
         let mut conn = self.redis_client.get_multiplexed_async_connection().await?;
         
-        let result: Option<(String, String)> = conn.blpop(Self::QUEUE_KEY, 5.0).await?;
+        let result: Option<(String, String)> = conn.blpop::<&str, Option<(String, String)>>(Self::QUEUE_KEY, 5.0).await?;
         
         if let Some((_key, json)) = result {
             let msg: QueuedWhatsAppMessage = serde_json::from_str(&json)?;
             
-            // Wait for rate limit (stored in Redis)
+            // 1. Proactive Rate Limiting (Burst 45, steady state 1/6s)
             self.wait_for_rate_limit(&msg.to, &mut conn).await?;
             
-            // Send with retry logic
-            let mut retry_count = 0;
+            // 2. Reactive Retry Logic (4^X for error 131056)
+            let mut x = 0;
             loop {
                 match self.send_message(&msg).await {
-                    Ok(_) => {
-                        // Update last sent time in Redis
-                        let last_sent_key = format!("{}{}", Self::LAST_SENT_PREFIX, msg.to);
-                        let now = chrono::Utc::now().timestamp();
-                        let _: () = conn.set(last_sent_key, now).await?;
-                        break;
-                    }
+                    Ok(_) => break,
                     Err(e) => {
                         let error_str = e.to_string();
                         if error_str.contains("131056") {
-                            let wait_secs = 4_i64.pow(retry_count);
-                            warn!("Rate limit hit for {}, retrying in {}s", msg.to, wait_secs);
-                            sleep(Duration::from_secs(wait_secs as u64)).await;
-                            retry_count += 1;
-                            if retry_count > 5 {
-                                error!("Max retries for {}: {}", msg.to, e);
+                            let wait_secs = 4_u64.pow(x as u32);
+                            warn!("WhatsApp 131056 rate limit for {}: retrying in 4^{} = {}s", msg.to, x, wait_secs);
+                            sleep(Duration::from_secs(wait_secs)).await;
+                            x += 1;
+                            if x > 5 {
+                                error!("Max retries (4^5) exceeded for {}: {}", msg.to, e);
                                 break;
                             }
                         } else {
-                            error!("Failed to send to {}: {}", msg.to, e);
+                            error!("WhatsApp send failure for {}: {}", msg.to, e);
                             break;
                         }
                     }
@@ -99,26 +95,47 @@ impl WhatsAppMessageQueue {
         Ok(())
     }
 
+    /// Implements Virtual Clock / Leaky Bucket for Meta's Bursting Rules.
+    /// Capacity: 45 messages (represented as 45 * 6s = 270s of "debt").
+    /// Steady rate: 1 message per 6 seconds.
     async fn wait_for_rate_limit(&self, recipient: &str, conn: &mut redis::aio::MultiplexedConnection) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
-        let last_sent_key = format!("{}{}", Self::LAST_SENT_PREFIX, recipient);
+        let tft_key = format!("{}{}", Self::TFT_PREFIX, recipient);
         
-        // Get last sent time from Redis
-        let last_sent: Option<i64> = conn.get(&last_sent_key).await?;
-        
-        if let Some(last_ts) = last_sent {
         let now = chrono::Utc::now().timestamp();
-            let since_last = now - last_ts;
+        let tft: i64 = conn.get::<_, Option<i64>>(&tft_key).await?.unwrap_or(0);
         
-            if since_last < Self::MIN_DELAY_SECS {
-                let wait_time = Self::MIN_DELAY_SECS - since_last;
-                warn!("Rate limiting {}: waiting {}s", recipient, wait_time);
-                sleep(Duration::from_secs(wait_time as u64)).await;
+        // Max "borrowing" is 45 messages * 6s = 270s
+        let max_debt_secs = Self::BURST_CAPACITY * Self::RATE_SECS;
+        
+        let mut wait_secs = 0;
+        let mut new_tft = if tft > now {
+            // Recipient is in debt
+            let debt = tft - now;
+            if debt + Self::RATE_SECS > max_debt_secs {
+                // Next message would exceed burst capacity
+                wait_secs = (debt + Self::RATE_SECS) - max_debt_secs;
+                tft + Self::RATE_SECS
+            } else {
+                tft + Self::RATE_SECS
             }
+        } else {
+            // Recipient has no active debt
+            now + Self::RATE_SECS
+        };
+
+        if wait_secs > 0 {
+            warn!("Burst capacity exhausted for {}: waiting {}s cooling off", recipient, wait_secs);
+            sleep(Duration::from_secs(wait_secs as u64)).await;
+            // Advance TFT if we waited (now has changed)
+            new_tft = chrono::Utc::now().timestamp() + (new_tft - (now + wait_secs as i64));
         }
         
+        // Store the new Theoretical Finish Time with TTL to clean up Redis
+        let _: () = conn.set(&tft_key, new_tft).await?;
+        let _: () = conn.expire(&tft_key, max_debt_secs + 3600).await?;
+        
         Ok(())
     }
-
     async fn send_message(&self, msg: &QueuedWhatsAppMessage) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
         let client = reqwest::Client::new();
         let url = format!(

src/core/bot/channels/whatsapp_queue_tests.rs

@@ -1,6 +1,6 @@
 #[cfg(test)]
 mod tests {
-    use super::super::whatsapp_queue::*;
+    use crate::core::bot::channels::whatsapp_queue::*;
     use std::sync::Arc;
     use tokio::time::Duration;
 
@@ -20,40 +20,8 @@ mod tests {
         assert!(result.is_ok());
     }
 
-    #[tokio::test]
-    async fn test_per_recipient_rate_limit() {
-        let queue = Arc::new(WhatsAppMessageQueue::new("redis://127.0.0.1:6379").unwrap());
-        
-        let msg1 = QueuedWhatsAppMessage {
-            to: "+5511999999999".to_string(),
-            message: "Message 1".to_string(),
-            api_key: "test_key".to_string(),
-            phone_number_id: "123456".to_string(),
-            api_version: "v17.0".to_string(),
-        };
-
-        let msg2 = QueuedWhatsAppMessage {
-            to: "+5511999999999".to_string(),
-            message: "Message 2".to_string(),
-            api_key: "test_key".to_string(),
-            phone_number_id: "123456".to_string(),
-            api_version: "v17.0".to_string(),
-        };
-
-        queue.enqueue(msg1).await.unwrap();
-        queue.enqueue(msg2).await.unwrap();
-
-        let start = std::time::Instant::now();
-        
-        // Process both messages
-        let _ = queue.process_next().await;
-        let _ = queue.process_next().await;
-
-        let elapsed = start.elapsed();
-        
-        // Should take at least 6 seconds due to Meta rate limiting
-        assert!(elapsed >= Duration::from_secs(6));
-    }
+    // Note: test_per_recipient_rate_limit removed because we now allow per-recipient bursting.
+    // Throttling is handled reactively via 131056 error code.
 
     #[tokio::test]
     async fn test_different_recipients_no_delay() {