优化上下文事件更新的处理逻辑

src/components/layout/status-bar-tokens.tsx

@@ -65,8 +65,12 @@ export function StatusBarTokens() {
     getConnSnapshot
   )
 
-  const liveContextUsed = activeConn?.usage?.used ?? null
-  const liveContextMax = activeConn?.usage?.size ?? null
+  const rawLiveUsed = activeConn?.usage?.used ?? null
+  const rawLiveSize = activeConn?.usage?.size ?? null
+  // Treat live used=0 as "no data" so we fall back to sessionStats —
+  // Claude Code sends used=0 for synthetic local commands (/context etc.)
+  const liveContextUsed = rawLiveUsed != null && rawLiveUsed > 0 ? rawLiveUsed : null
+  const liveContextMax = rawLiveSize != null && rawLiveSize > 0 ? rawLiveSize : null
 
   const contextUsed =
     liveContextUsed ?? sessionStats?.context_window_used_tokens ?? null

src/contexts/acp-connections-context.tsx

@@ -975,6 +975,12 @@ function connectionsReducer(
     case "USAGE_UPDATE": {
       const conn = state.get(action.contextKey)
       if (!conn) return state
+      // Ignore usage updates that reset used to 0 when we already have
+      // valid data — these come from synthetic responses for local commands
+      // like /context and would overwrite the real context window usage.
+      if (action.usage.used === 0 && conn.usage && conn.usage.used > 0) {
+        return state
+      }
       if (
         conn.usage?.used === action.usage.used &&
         conn.usage?.size === action.usage.size