refactor: narrow SSE limit public API surface

Author: DaleSeo

crates/rmcp/src/transport/common/client_side_sse.rs

@@ -15,7 +15,7 @@ use crate::model::ServerJsonRpcMessage;
 pub type BoxedSseResponse = BoxStream<'static, Result<Sse, SseError>>;
 
 /// Maximum raw size of one SSE event accepted from a remote server.
-pub const DEFAULT_MAX_SSE_EVENT_SIZE: usize = 16 * 1024 * 1024;
+pub(crate) const DEFAULT_MAX_SSE_EVENT_SIZE: usize = 16 * 1024 * 1024;
 
 #[derive(Debug, Error)]
 enum BoundedSseStreamError {

crates/rmcp/src/transport/streamable_http_client.rs

@@ -288,6 +288,12 @@ pub trait StreamableHttpClient: Clone + Send + 'static {
     + '_;
     /// Send a message while enforcing a maximum raw SSE event size.
     ///
+    /// `max_sse_event_size` is not a per-request option: it is the
+    /// transport-wide [`StreamableHttpClientTransportConfig::max_sse_event_size`]
+    /// value, passed identically on every call because the limit must be applied
+    /// inside the client (at the raw byte layer, before SSE parsing) rather than
+    /// by the caller.
+    ///
     /// Custom clients that parse SSE responses should override this method.
     /// The default implementation delegates to [`Self::post_message`].
     fn post_message_with_max_sse_event_size(
@@ -326,6 +332,12 @@ pub trait StreamableHttpClient: Clone + Send + 'static {
     + '_;
     /// Open an SSE stream while enforcing a maximum raw event size.
     ///
+    /// `max_sse_event_size` is not a per-request option: it is the
+    /// transport-wide [`StreamableHttpClientTransportConfig::max_sse_event_size`]
+    /// value, passed identically on every call because the limit must be applied
+    /// inside the client (at the raw byte layer, before SSE parsing) rather than
+    /// by the caller.
+    ///
     /// Custom clients that parse SSE responses should override this method.
     /// The default implementation delegates to [`Self::get_stream`].
     fn get_stream_with_max_sse_event_size(

crates/rmcp/src/transport/streamable_http_server.rs

@@ -3,6 +3,4 @@ pub mod session;
 pub mod tower;
 pub use session::{RestoreOutcome, SessionId, SessionManager, SessionRestoreMarker};
 #[cfg(all(feature = "transport-streamable-http-server", not(feature = "local")))]
-pub use tower::{
-    DEFAULT_MAX_REQUEST_BODY_BYTES, StreamableHttpServerConfig, StreamableHttpService,
-};
+pub use tower::{StreamableHttpServerConfig, StreamableHttpService};

crates/rmcp/src/transport/streamable_http_server/tower.rs

@@ -39,7 +39,7 @@ use crate::{
 };
 
 /// Default maximum POST request body size (4 MiB).
-pub const DEFAULT_MAX_REQUEST_BODY_BYTES: usize = 4 * 1024 * 1024;
+pub(crate) const DEFAULT_MAX_REQUEST_BODY_BYTES: usize = 4 * 1024 * 1024;
 
 #[non_exhaustive]
 #[derive(Debug, Clone)]