diff --git a/rust/crates/api/src/client.rs b/rust/crates/api/src/client.rs
index d7dacbe..6901de6 100644
--- a/rust/crates/api/src/client.rs
+++ b/rust/crates/api/src/client.rs
@@ -439,6 +439,19 @@ impl AnthropicClient {
             "beta_count".to_string(),
             Value::from(u64::try_from(self.request_profile.betas.len()).unwrap_or(u64::MAX)),
         );
+        if !self.request_profile.betas.is_empty() {
+            attributes.insert(
+                "betas".to_string(),
+                Value::Array(
+                    self.request_profile
+                        .betas
+                        .iter()
+                        .cloned()
+                        .map(Value::String)
+                        .collect(),
+                ),
+            );
+        }
         if !self.request_profile.extra_body.is_empty() {
             attributes.insert(
                 "extra_body_keys".to_string(),
diff --git a/rust/crates/api/tests/client_integration.rs b/rust/crates/api/tests/client_integration.rs
index 569c2fa..4b78d0e 100644
--- a/rust/crates/api/tests/client_integration.rs
+++ b/rust/crates/api/tests/client_integration.rs
@@ -75,7 +75,7 @@ async fn send_message_posts_json_and_parses_response() {
     );
     assert_eq!(
         request.headers.get("anthropic-beta").map(String::as_str),
-        Some("claude-code-20250219")
+        Some("claude-code-20250219,prompt-caching-scope-2026-01-05")
     );
     let body: serde_json::Value =
         serde_json::from_str(&request.body).expect("request body should be json");
@@ -86,7 +86,10 @@ async fn send_message_posts_json_and_parses_response() {
     assert!(body.get("stream").is_none());
     assert_eq!(body["tools"][0]["name"], json!("get_weather"));
     assert_eq!(body["tool_choice"]["type"], json!("auto"));
-    assert_eq!(body["betas"], json!(["claude-code-20250219"]));
+    assert_eq!(
+        body["betas"],
+        json!(["claude-code-20250219", "prompt-caching-scope-2026-01-05"])
+    );
 }
 
 #[tokio::test]
@@ -133,7 +136,7 @@ async fn send_message_applies_request_profile_and_records_telemetry() {
     let request = captured.first().expect("server should capture request");
     assert_eq!(
         request.headers.get("anthropic-beta").map(String::as_str),
-        Some("claude-code-20250219,tools-2026-04-01")
+        Some("claude-code-20250219,prompt-caching-scope-2026-01-05,tools-2026-04-01")
     );
     assert_eq!(
         request.headers.get("user-agent").map(String::as_str),
@@ -144,7 +147,11 @@ async fn send_message_applies_request_profile_and_records_telemetry() {
     assert_eq!(body["metadata"]["source"], json!("clawd-code"));
     assert_eq!(
         body["betas"],
-        json!(["claude-code-20250219", "tools-2026-04-01"])
+        json!([
+            "claude-code-20250219",
+            "prompt-caching-scope-2026-01-05",
+            "tools-2026-04-01"
+        ])
     );
 
     let events = sink.events();
diff --git a/rust/crates/telemetry/src/lib.rs b/rust/crates/telemetry/src/lib.rs
index 4a471cc..6e369e1 100644
--- a/rust/crates/telemetry/src/lib.rs
+++ b/rust/crates/telemetry/src/lib.rs
@@ -13,6 +13,7 @@ pub const DEFAULT_ANTHROPIC_VERSION: &str = "2023-06-01";
 pub const DEFAULT_APP_NAME: &str = "claude-code";
 pub const DEFAULT_RUNTIME: &str = "rust";
 pub const DEFAULT_AGENTIC_BETA: &str = "claude-code-20250219";
+pub const DEFAULT_PROMPT_CACHING_SCOPE_BETA: &str = "prompt-caching-scope-2026-01-05";
 
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct ClientIdentity {
@@ -65,7 +66,10 @@ impl AnthropicRequestProfile {
         Self {
             anthropic_version: DEFAULT_ANTHROPIC_VERSION.to_string(),
             client_identity,
-            betas: vec![DEFAULT_AGENTIC_BETA.to_string()],
+            betas: vec![
+                DEFAULT_AGENTIC_BETA.to_string(),
+                DEFAULT_PROMPT_CACHING_SCOPE_BETA.to_string(),
+            ],
             extra_body: Map::new(),
         }
     }
@@ -445,7 +449,8 @@ mod tests {
                 ("user-agent".to_string(), "claude-code/1.2.3".to_string()),
                 (
                     "anthropic-beta".to_string(),
-                    "claude-code-20250219,tools-2026-04-01".to_string(),
+                    "claude-code-20250219,prompt-caching-scope-2026-01-05,tools-2026-04-01"
+                        .to_string(),
                 ),
             ]
         );
@@ -459,7 +464,11 @@ mod tests {
         );
         assert_eq!(
             body["betas"],
-            serde_json::json!(["claude-code-20250219", "tools-2026-04-01"])
+            serde_json::json!([
+                "claude-code-20250219",
+                "prompt-caching-scope-2026-01-05",
+                "tools-2026-04-01"
+            ])
         );
     }