diff --git a/crates/goose-api/Cargo.toml b/crates/goose-api/Cargo.toml
index 1caa2ffe..0db532b7 100644
--- a/crates/goose-api/Cargo.toml
+++ b/crates/goose-api/Cargo.toml
@@ -22,3 +22,7 @@ futures-util = "0.3"
 # For session IDs
 uuid = { version = "1", features = ["serde", "v4"] }
  # Add dynamic-library for extension loading
+
+[dev-dependencies]
+tempfile = "3"
+async-trait = "0.1"
diff --git a/crates/goose-api/src/handlers.rs b/crates/goose-api/src/handlers.rs
index f731ea88..a1337579 100644
--- a/crates/goose-api/src/handlers.rs
+++ b/crates/goose-api/src/handlers.rs
@@ -6,7 +6,7 @@ use futures_util::TryStreamExt;
 use tracing::{info, warn, error};
 use mcp_core::tool::Tool;
 use goose::agents::{extension::Envs, extension_manager::ExtensionManager, ExtensionConfig, Agent, SessionConfig};
-use goose::message::Message;
+use goose::message::{Message, MessageContent};
 use goose::session::{self, Identifier};
 use goose::config::Config;
 use std::sync::LazyLock;
@@ -135,6 +135,30 @@ pub async fn start_session_handler(
     match result {
         Ok(mut stream) => {
             if let Ok(Some(response)) = stream.try_next().await {
+                if matches!(response.content.first(), Some(MessageContent::ContextLengthExceeded(_))) {
+                    match agent.summarize_context(&messages).await {
+                        Ok((summarized, _)) => {
+                            messages = summarized;
+                            if let Err(e) = session::persist_messages(&session_path, &messages, provider.clone()).await {
+                                warn!("Failed to persist session {}: {}", session_name, e);
+                            }
+
+                            let api_response = StartSessionResponse {
+                                message: "Conversation summarized to fit context window".to_string(),
+                                status: "warning".to_string(),
+                                session_id,
+                            };
+                            return Ok(warp::reply::with_status(
+                                warp::reply::json(&api_response),
+                                warp::http::StatusCode::OK,
+                            ));
+                        }
+                        Err(e) => {
+                            warn!("Failed to summarize context: {}", e);
+                        }
+                    }
+                }
+
                 let response_text = response.as_concat_text();
                 messages.push(response);
                 if let Err(e) = session::persist_messages(&session_path, &messages, provider.clone()).await {
@@ -223,6 +247,28 @@ pub async fn reply_session_handler(
     match result {
         Ok(mut stream) => {
             if let Ok(Some(response)) = stream.try_next().await {
+                if matches!(response.content.first(), Some(MessageContent::ContextLengthExceeded(_))) {
+                    match agent.summarize_context(&messages).await {
+                        Ok((summarized, _)) => {
+                            messages = summarized;
+                            if let Err(e) = session::persist_messages(&session_path, &messages, provider.clone()).await {
+                                warn!("Failed to persist session {}: {}", session_name, e);
+                            }
+                            let api_response = ApiResponse {
+                                message: "Conversation summarized to fit context window".to_string(),
+                                status: "warning".to_string(),
+                            };
+                            return Ok(warp::reply::with_status(
+                                warp::reply::json(&api_response),
+                                warp::http::StatusCode::OK,
+                            ));
+                        }
+                        Err(e) => {
+                            warn!("Failed to summarize context: {}", e);
+                        }
+                    }
+                }
+
                 let response_text = response.as_concat_text();
                 messages.push(response);
                 if let Err(e) = session::persist_messages(&session_path, &messages, provider.clone()).await {
diff --git a/crates/goose-api/src/tests.rs b/crates/goose-api/src/tests.rs
index 302cf8c3..607064d4 100644
--- a/crates/goose-api/src/tests.rs
+++ b/crates/goose-api/src/tests.rs
@@ -1,10 +1,107 @@
 #[cfg(test)]
 mod tests {
     use super::*;
+    use goose::message::{Message, MessageContent};
+    use goose::model::ModelConfig;
+    use goose::providers::{
+        base::{Provider, ProviderMetadata, ProviderUsage, Usage},
+        errors::ProviderError,
+    };
+    use mcp_core::tool::Tool;
+    use std::sync::Arc;
+    use tempfile::TempDir;
+    use warp::reply::Reply;
+    use goose::session::{self, Identifier};
+    use uuid::Uuid;
+    use hyper::body;
+
+    #[derive(Clone)]
+    struct ContextProvider {
+        model_config: ModelConfig,
+    }
+
+    #[async_trait::async_trait]
+    impl Provider for ContextProvider {
+        fn metadata() -> ProviderMetadata {
+            ProviderMetadata::empty()
+        }
+
+        fn get_model_config(&self) -> ModelConfig {
+            self.model_config.clone()
+        }
+
+        async fn complete(
+            &self,
+            system: &str,
+            _messages: &[Message],
+            _tools: &[Tool],
+        ) -> Result<(Message, ProviderUsage), ProviderError> {
+            if system.contains("summarizing") {
+                Ok((
+                    Message::user().with_text("summary"),
+                    ProviderUsage::new("mock".to_string(), Usage::default()),
+                ))
+            } else {
+                Err(ProviderError::ContextLengthExceeded("too long".to_string()))
+            }
+        }
+    }
+
+    async fn setup() -> (TempDir, Uuid) {
+        let tmp = tempfile::tempdir().unwrap();
+        std::env::set_var("HOME", tmp.path());
+
+        let provider = Arc::new(ContextProvider {
+            model_config: ModelConfig::new("test".to_string()),
+        });
+        let agent = AGENT.lock().await;
+        agent.update_provider(provider).await.unwrap();
+        drop(agent);
+
+        let req = SessionRequest {
+            prompt: "start".repeat(1000),
+        };
+        let reply = start_session_handler(req, "key".to_string()).await.unwrap();
+        let resp = reply.into_response();
+        let body = body::to_bytes(resp.into_body()).await.unwrap();
+        let start: StartSessionResponse = serde_json::from_slice(&body).unwrap();
+        (tmp, start.session_id)
+    }
 
     #[tokio::test]
     async fn build_routes_compiles() {
         let _routes = build_routes("test-key".to_string());
-        // Just ensure building routes doesn't panic
+    }
+
+    #[tokio::test]
+    async fn summarizes_large_history_on_start() {
+        let (tmp, session_id) = setup().await;
+
+        let session_path = session::get_path(Identifier::Name(session_id.to_string()));
+        let messages = session::read_messages(&session_path).unwrap();
+        assert!(messages.iter().any(|m| m.as_concat_text().contains("summary")));
+        drop(tmp);
+    }
+
+    #[tokio::test]
+    async fn summarizes_large_history_on_reply() {
+        let (tmp, session_id) = setup().await;
+
+        let req = SessionReplyRequest {
+            session_id,
+            prompt: "reply".repeat(1000),
+        };
+        let reply = reply_session_handler(req, "key".to_string()).await.unwrap();
+        let resp = reply.into_response();
+        let body = body::to_bytes(resp.into_body()).await.unwrap();
+        let api: ApiResponse = serde_json::from_slice(&body).unwrap();
+        assert_eq!(api.status, "warning");
+
+        let session_path = session::get_path(Identifier::Name(session_id.to_string()));
+        let messages = session::read_messages(&session_path).unwrap();
+        assert!(messages
+            .iter()
+            .all(|m| !matches!(m.content.first(), Some(MessageContent::ContextLengthExceeded(_)))));
+        drop(tmp);
     }
 }