fix: add per-sender conversation history for channel messages

Channel messages (Telegram, Discord, etc.) previously had no multi-turn
context — each incoming message was processed with a fresh history
containing only the system prompt and the current user message.

This patch:
- Maintains a per-sender conversation history map (Arc<Mutex<HashMap>>)
- Restores prior turns when processing each new message
- Saves user + assistant turns after successful LLM response
- Caps history at 50 messages per sender to bound memory usage

Fixes the channel context continuity issue where the bot would respond
with 'I have no context' to every follow-up question.

src/channels/mod.rs

@@ -45,9 +45,14 @@ use std::collections::HashMap;
 use std::fmt::Write;
 use std::path::PathBuf;
 use std::process::Command;
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 use std::time::{Duration, Instant};
 
+/// Per-sender conversation history for channel messages.
+type ConversationHistoryMap = Arc<Mutex<HashMap<String, Vec<ChatMessage>>>>;
+/// Maximum history messages to keep per sender.
+const MAX_CHANNEL_HISTORY: usize = 50;
+
 /// Maximum characters per injected workspace file (matches `OpenClaw` default).
 const BOOTSTRAP_MAX_CHARS: usize = 20_000;
 
@@ -73,6 +78,7 @@ struct ChannelRuntimeContext {
     auto_save_memory: bool,
     max_tool_iterations: usize,
     min_relevance_score: f64,
+    conversation_histories: ConversationHistoryMap,
 }
 
 fn conversation_memory_key(msg: &traits::ChannelMessage) -> String {
@@ -212,10 +218,19 @@ async fn process_channel_message(ctx: Arc<ChannelRuntimeContext>, msg: traits::C
     println!("  ⏳ Processing message...");
     let started_at = Instant::now();
 
-    let mut history = vec![
-        ChatMessage::system(ctx.system_prompt.as_str()),
-        ChatMessage::user(&enriched_message),
-    ];
+    // Build history from per-sender conversation cache
+    let history_key = format!("{}_{}", msg.channel, msg.sender);
+    let mut prior_turns = ctx
+        .conversation_histories
+        .lock()
+        .unwrap_or_else(|e| e.into_inner())
+        .get(&history_key)
+        .cloned()
+        .unwrap_or_default();
+
+    let mut history = vec![ChatMessage::system(ctx.system_prompt.as_str())];
+    history.append(&mut prior_turns);
+    history.push(ChatMessage::user(&enriched_message));
 
     if let Some(instructions) = channel_delivery_instructions(&msg.channel) {
         history.push(ChatMessage::system(instructions));
@@ -311,6 +326,20 @@ async fn process_channel_message(ctx: Arc<ChannelRuntimeContext>, msg: traits::C
 
     match llm_result {
         Ok(Ok(response)) => {
+            // Save user + assistant turn to per-sender history
+            {
+                let mut histories = ctx
+                    .conversation_histories
+                    .lock()
+                    .unwrap_or_else(|e| e.into_inner());
+                let turns = histories.entry(history_key).or_insert_with(Vec::new);
+                turns.push(ChatMessage::user(&enriched_message));
+                turns.push(ChatMessage::assistant(&response));
+                // Trim to MAX_CHANNEL_HISTORY (keep recent turns)
+                while turns.len() > MAX_CHANNEL_HISTORY {
+                    turns.remove(0);
+                }
+            }
             println!(
                 "  🤖 Reply ({}ms): {}",
                 started_at.elapsed().as_millis(),
@@ -1379,6 +1408,7 @@ pub async fn start_channels(config: Config) -> Result<()> {
         auto_save_memory: config.memory.auto_save,
         max_tool_iterations: config.agent.max_tool_iterations,
         min_relevance_score: config.memory.min_relevance_score,
+        conversation_histories: Arc::new(Mutex::new(HashMap::new())),
     });
 
     run_message_dispatch_loop(rx, runtime_ctx, max_in_flight_messages).await;
@@ -1545,6 +1575,39 @@ mod tests {
         }
     }
 
+    #[derive(Default)]
+    struct HistoryCaptureProvider {
+        calls: std::sync::Mutex<Vec<Vec<(String, String)>>>,
+    }
+
+    #[async_trait::async_trait]
+    impl Provider for HistoryCaptureProvider {
+        async fn chat_with_system(
+            &self,
+            _system_prompt: Option<&str>,
+            _message: &str,
+            _model: &str,
+            _temperature: f64,
+        ) -> anyhow::Result<String> {
+            Ok("fallback".to_string())
+        }
+
+        async fn chat_with_history(
+            &self,
+            messages: &[ChatMessage],
+            _model: &str,
+            _temperature: f64,
+        ) -> anyhow::Result<String> {
+            let snapshot = messages
+                .iter()
+                .map(|m| (m.role.clone(), m.content.clone()))
+                .collect::<Vec<_>>();
+            let mut calls = self.calls.lock().unwrap_or_else(|e| e.into_inner());
+            calls.push(snapshot);
+            Ok(format!("response-{}", calls.len()))
+        }
+    }
+
     struct MockPriceTool;
 
     #[async_trait::async_trait]
@@ -1605,6 +1668,7 @@ mod tests {
             auto_save_memory: false,
             max_tool_iterations: 10,
             min_relevance_score: 0.0,
+            conversation_histories: Arc::new(Mutex::new(HashMap::new())),
         });
 
         process_channel_message(
@@ -1648,6 +1712,7 @@ mod tests {
             auto_save_memory: false,
             max_tool_iterations: 10,
             min_relevance_score: 0.0,
+            conversation_histories: Arc::new(Mutex::new(HashMap::new())),
         });
 
         process_channel_message(
@@ -1745,6 +1810,7 @@ mod tests {
             auto_save_memory: false,
             max_tool_iterations: 10,
             min_relevance_score: 0.0,
+            conversation_histories: Arc::new(Mutex::new(HashMap::new())),
         });
 
         let (tx, rx) = tokio::sync::mpsc::channel::<traits::ChannelMessage>(4);
@@ -2116,6 +2182,75 @@ mod tests {
         assert!(context.contains("Age is 45"));
     }
 
+    #[tokio::test]
+    async fn process_channel_message_restores_per_sender_history_on_follow_ups() {
+        let channel_impl = Arc::new(RecordingChannel::default());
+        let channel: Arc<dyn Channel> = channel_impl.clone();
+
+        let mut channels_by_name = HashMap::new();
+        channels_by_name.insert(channel.name().to_string(), channel);
+
+        let provider_impl = Arc::new(HistoryCaptureProvider::default());
+
+        let runtime_ctx = Arc::new(ChannelRuntimeContext {
+            channels_by_name: Arc::new(channels_by_name),
+            provider: provider_impl.clone(),
+            memory: Arc::new(NoopMemory),
+            tools_registry: Arc::new(vec![]),
+            observer: Arc::new(NoopObserver),
+            system_prompt: Arc::new("test-system-prompt".to_string()),
+            model: Arc::new("test-model".to_string()),
+            temperature: 0.0,
+            auto_save_memory: false,
+            max_tool_iterations: 5,
+            min_relevance_score: 0.0,
+            conversation_histories: Arc::new(Mutex::new(HashMap::new())),
+        });
+
+        process_channel_message(
+            runtime_ctx.clone(),
+            traits::ChannelMessage {
+                id: "msg-a".to_string(),
+                sender: "alice".to_string(),
+                reply_target: "chat-1".to_string(),
+                content: "hello".to_string(),
+                channel: "test-channel".to_string(),
+                timestamp: 1,
+            },
+        )
+        .await;
+
+        process_channel_message(
+            runtime_ctx,
+            traits::ChannelMessage {
+                id: "msg-b".to_string(),
+                sender: "alice".to_string(),
+                reply_target: "chat-1".to_string(),
+                content: "follow up".to_string(),
+                channel: "test-channel".to_string(),
+                timestamp: 2,
+            },
+        )
+        .await;
+
+        let calls = provider_impl
+            .calls
+            .lock()
+            .unwrap_or_else(|e| e.into_inner());
+        assert_eq!(calls.len(), 2);
+        assert_eq!(calls[0].len(), 2);
+        assert_eq!(calls[0][0].0, "system");
+        assert_eq!(calls[0][1].0, "user");
+        assert_eq!(calls[1].len(), 4);
+        assert_eq!(calls[1][0].0, "system");
+        assert_eq!(calls[1][1].0, "user");
+        assert_eq!(calls[1][2].0, "assistant");
+        assert_eq!(calls[1][3].0, "user");
+        assert!(calls[1][1].1.contains("hello"));
+        assert!(calls[1][2].1.contains("response-1"));
+        assert!(calls[1][3].1.contains("follow up"));
+    }
+
     // ── AIEOS Identity Tests (Issue #168) ─────────────────────────
 
     #[test]