From 436204eb2b614f04490700126de39fb05e5be6e4 Mon Sep 17 00:00:00 2001
From: Tryanks <tryanks@outlook.com>
Date: Tue, 13 Oct 2026 09:07:12 +0800
Subject: [PATCH] perf(protocol): send usage changes without full session
 status

---
 crates/protocol/src/event.rs        |  4 ++++
 crates/protocol/src/lib.rs          |  2 ++
 crates/runtime/src/app/snapshots.rs | 17 +++++++++++++++--
 crates/ui/src/store/mod.rs          | 24 ++++++++++++++++++++++++
 4 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/crates/protocol/src/event.rs b/crates/protocol/src/event.rs
index 96673acf1..df7c41dc8 100644
--- a/crates/protocol/src/event.rs
+++ b/crates/protocol/src/event.rs
@@ -68,6 +68,10 @@ pub enum ServerEvent {
     },
     SessionEvent(StoredEvent),
     SessionStatusReplaced(Box<SessionStatus>),
+    SessionUsageChanged {
+        usage: Option<TokenUsage>,
+        context_window: Option<u64>,
+    },
     SessionPlanReplaced(SessionPlan),
     ProvidersReplaced(ProvidersStatus),
     GitStatusReplaced(GitStatusStatus),
diff --git a/crates/protocol/src/lib.rs b/crates/protocol/src/lib.rs
index 883533adb..f306fd084 100644
--- a/crates/protocol/src/lib.rs
+++ b/crates/protocol/src/lib.rs
@@ -150,6 +150,8 @@ pub use wire::{
 // host then sends the text as an ordinary turn. Index subscriptions may carry
 // known_index; matching content receives IndexUnchanged instead of a snapshot.
 // ReadFilePreview rejects files larger than 512 KiB before transferring bytes.
+// SessionUsageChanged carries usage and meter capacity when the rest of the
+// session status is unchanged; subscription replies remain full statuses.
 pub const PROTOCOL_VERSION: u32 = 12;
 
 #[cfg(test)]
diff --git a/crates/runtime/src/app/snapshots.rs b/crates/runtime/src/app/snapshots.rs
index 4250ac99d..197f3b1ab 100644
--- a/crates/runtime/src/app/snapshots.rs
+++ b/crates/runtime/src/app/snapshots.rs
@@ -109,12 +109,25 @@ impl DomainDiff {
             .collect();
         changed_ids.sort_unstable();
         for id in changed_ids {
-            let status = session_statuses[id].clone();
+            let status = &session_statuses[id];
+            let usage_only = self.session_statuses.get_mut(id).is_some_and(|previous| {
+                previous.usage = status.usage;
+                previous.context_window = status.context_window;
+                previous == status
+            });
+            let event = if usage_only {
+                ServerEvent::SessionUsageChanged {
+                    usage: status.usage,
+                    context_window: status.context_window,
+                }
+            } else {
+                ServerEvent::SessionStatusReplaced(Box::new(status.clone()))
+            };
             emit_replacement(
                 Topic::SessionStatus {
                     session_id: id.to_string(),
                 },
-                ServerEvent::SessionStatusReplaced(Box::new(status)),
+                event,
                 cx,
             );
         }
diff --git a/crates/ui/src/store/mod.rs b/crates/ui/src/store/mod.rs
index c0dfa8ff5..05f069c72 100644
--- a/crates/ui/src/store/mod.rs
+++ b/crates/ui/src/store/mod.rs
@@ -1342,6 +1342,30 @@ impl WorkspaceStore {
                     self.sync_active_conversation_ui();
                 }
             }
+            (
+                Topic::SessionStatus { session_id },
+                ServerEvent::SessionUsageChanged {
+                    usage,
+                    context_window,
+                },
+            ) if self.baseline_topics.contains(&envelope.topic) => {
+                if let Some(status) = self
+                    .threads
+                    .get_mut(session_id)
+                    .and_then(|thread| thread.status.as_mut())
+                {
+                    status.usage = *usage;
+                    status.context_window = *context_window;
+                }
+                if let Some(status) = self
+                    .session_status_replica
+                    .as_mut()
+                    .filter(|status| status.session_id == *session_id)
+                {
+                    status.usage = *usage;
+                    status.context_window = *context_window;
+                }
+            }
             (Topic::SessionPlan { session_id }, ServerEvent::SessionPlanReplaced(plan))
                 if plan.session_id == *session_id =>
             {