diff --git a/src-tauri/src/proxy/cache_injector.rs b/src-tauri/src/proxy/cache_injector.rs
index e2b0464ad..a6bf8c9c9 100644
--- a/src-tauri/src/proxy/cache_injector.rs
+++ b/src-tauri/src/proxy/cache_injector.rs
@@ -13,6 +13,15 @@ pub fn inject(body: &mut Value, config: &OptimizerConfig) {
 
     let existing = count_existing(body);
 
+    if existing > 4 {
+        // Existing markers are caller-owned. Do not silently delete or reorder
+        // them; surface the invalid/unsupported total and leave validation to
+        // the upstream provider.
+        log::warn!(
+            "[OPT] cache: existing breakpoint count {existing} exceeds the supported total of 4; preserving caller input"
+        );
+    }
+
     // 升级已有断点的 TTL
     upgrade_existing_ttl(body, &config.cache_ttl);
 
@@ -288,6 +297,32 @@ mod tests {
             .is_some());
     }
 
+    #[test]
+    fn test_more_than_four_existing_breakpoints_are_preserved() {
+        let mut body = json!({
+            "model": "test",
+            "tools": [
+                {"name": "t1", "cache_control": {"type": "ephemeral"}},
+                {"name": "t2", "cache_control": {"type": "ephemeral"}}
+            ],
+            "system": [
+                {"type": "text", "text": "s1", "cache_control": {"type": "ephemeral"}},
+                {"type": "text", "text": "s2", "cache_control": {"type": "ephemeral"}}
+            ],
+            "messages": [{"role": "user", "content": [
+                {"type": "text", "text": "m1", "cache_control": {"type": "ephemeral"}},
+                {"type": "text", "text": "m2"}
+            ]}]
+        });
+
+        inject(&mut body, &default_config());
+
+        assert_eq!(count_existing(&body), 5);
+        assert!(body["messages"][0]["content"][1]
+            .get("cache_control")
+            .is_none());
+    }
+
     #[test]
     fn test_system_string_converted_to_array() {
         let mut body = json!({
diff --git a/src-tauri/src/proxy/forwarder.rs b/src-tauri/src/proxy/forwarder.rs
index ab6ab134e..5d62fed39 100644
--- a/src-tauri/src/proxy/forwarder.rs
+++ b/src-tauri/src/proxy/forwarder.rs
@@ -1450,7 +1450,7 @@ impl RequestForwarder {
             // configured TTL rather than silently forcing 5m on this conversion path.
             // otherwise system/tools/history are re-sent at full price every round,
             // inflating cost and first-token latency. The injector handles the
-            // string→array `system` conversion and the 4-breakpoint cap.
+            // string→array `system` conversion and the new-breakpoint budget.
             super::cache_injector::inject(
                 &mut anthropic_body,
                 &super::types::OptimizerConfig {