From 9e9bc8a144667a6b7debfd4f0c7a31ff0e11493a Mon Sep 17 00:00:00 2001
From: Can Celik <ogulcancelik@gmail.com>
Date: Sun, 6 Sep 2026 02:27:06 +0300
Subject: feat: manage multiple ssh machines from one client (#3670)

---
 src/client/endpoint/message_policy.rs | 124 ++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 src/client/endpoint/message_policy.rs

(limited to 'src/client/endpoint/message_policy.rs')

diff --git a/src/client/endpoint/message_policy.rs b/src/client/endpoint/message_policy.rs
new file mode 100644
index 00000000..5e84325a
--- /dev/null
+++ b/src/client/endpoint/message_policy.rs
@@ -0,0 +1,124 @@
+use crate::protocol::ServerMessage;
+
+/// Effects that are meaningful only for the endpoint currently holding the host presentation
+/// lease. During a frozen handoff they are intentionally dropped and the committed target asks
+/// for one bounded replay, rather than allowing target graphics or modes onto the source frame.
+pub(crate) fn is_presentation_effect(message: &ServerMessage) -> bool {
+    matches!(
+        message,
+        ServerMessage::MouseCapture { .. }
+            | ServerMessage::ClientShellKeyboardReportAll { .. }
+            | ServerMessage::WindowTitle { .. }
+            | ServerMessage::Graphics { .. }
+            | ServerMessage::GraphicsFile { .. }
+            | ServerMessage::GraphicsTransmissionRetired { .. }
+            | ServerMessage::TerminalBell { .. }
+    )
+}
+
+pub(crate) fn accepts_endpoint_message(
+    endpoint_active: bool,
+    activation_message: bool,
+    command_response: bool,
+    message: &ServerMessage,
+) -> bool {
+    endpoint_active
+        || matches!(
+            message,
+            ServerMessage::EndpointControl { .. }
+                | ServerMessage::SemanticNotification(_)
+                | ServerMessage::ServerShutdown { .. }
+                | ServerMessage::ClientShellSnapshot(_)
+                | ServerMessage::Welcome { .. }
+        )
+        || (activation_message
+            && matches!(
+                message,
+                ServerMessage::PaneSurface(_)
+                    | ServerMessage::ClientShellEndpointResponseChunk { .. }
+            ))
+        || (command_response
+            && matches!(
+                message,
+                ServerMessage::ClientShellEndpointResponseChunk { .. }
+            ))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn inactive_endpoints_deliver_metadata_but_not_presentation_effects() {
+        assert!(accepts_endpoint_message(
+            false,
+            false,
+            false,
+            &ServerMessage::EndpointControl {
+                kind: "snapshot".into(),
+                data: "{}".into(),
+            }
+        ));
+        assert!(!accepts_endpoint_message(
+            false,
+            false,
+            false,
+            &ServerMessage::Clipboard {
+                data: "text".into()
+            }
+        ));
+        assert!(!accepts_endpoint_message(
+            false,
+            false,
+            false,
+            &ServerMessage::WindowTitle {
+                title: Some("remote".into())
+            }
+        ));
+    }
+
+    #[test]
+    fn frozen_handoffs_drop_target_effects_until_the_post_commit_resync() {
+        assert!(is_presentation_effect(&ServerMessage::MouseCapture {
+            enabled: true,
+            sgr_pixels: false,
+        }));
+        assert!(is_presentation_effect(&ServerMessage::GraphicsFile {
+            path: "asset".into(),
+            expected_len: 1,
+            image_id: 1,
+            transfer_id: 1,
+            leading: Vec::new(),
+            control: "a=t".into(),
+            surface_asset: None,
+        }));
+        assert!(!is_presentation_effect(&ServerMessage::EndpointControl {
+            kind: "shell.snapshot.v1".into(),
+            data: "{}".into(),
+        }));
+    }
+
+    #[test]
+    fn pending_activation_accepts_only_its_surface_lane() {
+        assert!(accepts_endpoint_message(
+            false,
+            true,
+            false,
+            &ServerMessage::ClientShellEndpointResponseChunk {
+                boot_id: "boot".into(),
+                request_id: "surface".into(),
+                final_chunk: true,
+                data: Vec::new(),
+            }
+        ));
+        assert!(!accepts_endpoint_message(
+            false,
+            true,
+            false,
+            &ServerMessage::MouseCapture {
+                enabled: true,
+                sgr_pixels: false,
+            }
+        ));
+    }
+}
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