[EC Connector] Add EC Transfer Params (#42433)

Signed-off-by: omerpaz95 <omerpaz95@gmail.com>
Co-authored-by: Or Ozeri <oro@il.ibm.com>

rust/src/text/src/output/decoded.rs

@@ -44,6 +44,9 @@ pub struct Finished {
     pub finish_reason: FinishReason,
     /// Connector-specific KV transfer parameters for disaggregated serving.
     pub kv_transfer_params: Option<serde_json::Value>,
+    /// Connector-specific encoder cache transfer parameters for disaggregated
+    /// serving.
+    pub ec_transfer_params: Option<serde_json::Value>,
 }
 
 /// Internal decoded-text event emitted before higher-level assistant
@@ -151,6 +154,7 @@ pub async fn decoded_text_event_stream(
         let decoder = decoder.as_mut().unwrap();
 
         let kv_transfer_params = output.kv_transfer_params;
+        let ec_transfer_params = output.ec_transfer_params;
         let mut finish_reason = output.finish_reason;
         let mut stop_str_matched = false;
         let suppress_terminal_stop_token = finish_reason.as_ref().is_some_and(|r| r.is_stop())
@@ -275,6 +279,7 @@ pub async fn decoded_text_event_stream(
                     },
                     finish_reason: reason,
                     kv_transfer_params,
+                    ec_transfer_params,
                 }),
             })
             .await;

rust/src/text/src/output/mod.rs

@@ -26,6 +26,9 @@ pub struct CollectedTextOutput {
     pub usage: vllm_llm::TokenUsage,
     /// Connector-specific KV transfer parameters for disaggregated serving.
     pub kv_transfer_params: Option<serde_json::Value>,
+    /// Connector-specific encoder cache transfer parameters for disaggregated
+    /// serving.
+    pub ec_transfer_params: Option<serde_json::Value>,
 }
 
 #[allow(clippy::manual_async_fn, reason = "specify `Send` bound")]
@@ -77,6 +80,7 @@ impl<T: TextOutputStream> T {
                                 finish_reason: FinishReason::Error,
                                 usage: vllm_llm::TokenUsage::default(),
                                 kv_transfer_params: None,
+                                ec_transfer_params: None,
                             })
                         };
 
@@ -85,6 +89,7 @@ impl<T: TextOutputStream> T {
                             collected.finish_reason = finished.finish_reason;
                             collected.usage = finished.usage;
                             collected.kv_transfer_params = finished.kv_transfer_params;
+                            collected.ec_transfer_params = finished.ec_transfer_params;
                             return Ok(collected);
                         }
                     }
@@ -156,6 +161,7 @@ mod tests {
                     },
                     finish_reason: FinishReason::stop_eos(),
                     kv_transfer_params: None,
+                    ec_transfer_params: None,
                 }),
             }),
         ]);
@@ -273,6 +279,7 @@ mod tests {
                     },
                     finish_reason: FinishReason::stop_eos(),
                     kv_transfer_params: None,
+                    ec_transfer_params: None,
                 }),
             }),
         ]);