feat: wire OpenAI responses session affinity

apps/aether-gateway/src/ai_serving/planner/standard/openai/responses/decision/support.rs

@@ -32,6 +32,7 @@ use crate::ai_serving::{
     resolve_local_decision_execution_runtime_auth_context, ExecutionRuntimeAuthContext,
     GatewayControlDecision, PlannerAppState,
 };
+use crate::client_session_affinity::client_session_affinity_from_parts;
 use crate::{AppState, GatewayError};
 
 use super::LocalOpenAiResponsesSpec;
@@ -42,6 +43,7 @@ pub(crate) use crate::ai_serving::planner::decision_input::LocalRequestedModelDe
 
 pub(crate) async fn resolve_local_openai_responses_decision_input(
     state: &AppState,
+    parts: &http::request::Parts,
     trace_id: &str,
     decision: &GatewayControlDecision,
     body_json: &serde_json::Value,
@@ -128,6 +130,7 @@ pub(crate) async fn resolve_local_openai_responses_decision_input(
 
     let mut input = build_local_requested_model_decision_input(resolved_input, requested_model);
     input.request_auth_channel = decision.request_auth_channel.clone();
+    input.client_session_affinity = client_session_affinity_from_parts(parts, Some(body_json));
     Some(input)
 }
 
@@ -154,6 +157,7 @@ pub(crate) async fn materialize_local_openai_responses_candidate_attempts(
         spec_metadata.require_streaming,
         input.required_capabilities.as_ref(),
         &input.auth_snapshot,
+        input.client_session_affinity.as_ref(),
         true,
         LocalCandidatePreselectionKeyMode::ProviderEndpointKeyModelAndApiFormat,
     )
@@ -164,6 +168,7 @@ pub(crate) async fn materialize_local_openai_responses_candidate_attempts(
         spec_metadata.api_format,
         Some(&input.requested_model),
         Some(&input.auth_snapshot),
+        input.client_session_affinity.as_ref(),
         input.required_capabilities.as_ref(),
         sticky_session_token.as_deref(),
         input.request_auth_channel.as_deref(),
@@ -249,6 +254,7 @@ pub(crate) async fn build_local_openai_responses_candidate_attempt_source<'a>(
             &input.requested_model,
             spec_metadata.require_streaming,
             &input.auth_snapshot,
+            input.client_session_affinity.as_ref(),
             input.required_capabilities.as_ref(),
             sticky_session_token.as_deref(),
             input.request_auth_channel.as_deref(),

apps/aether-gateway/src/ai_serving/planner/standard/openai/responses/mod.rs

@@ -101,7 +101,7 @@ pub(crate) async fn maybe_build_sync_local_openai_responses_decision_payload(
     };
 
     let Some(input) = resolve_local_openai_responses_decision_input(
-        state, trace_id, decision, body_json, plan_kind,
+        state, parts, trace_id, decision, body_json, plan_kind,
     )
     .await
     else {
@@ -139,7 +139,7 @@ pub(crate) async fn maybe_build_stream_local_openai_responses_decision_payload(
     };
 
     let Some(input) = resolve_local_openai_responses_decision_input(
-        state, trace_id, decision, body_json, plan_kind,
+        state, parts, trace_id, decision, body_json, plan_kind,
     )
     .await
     else {

apps/aether-gateway/src/ai_serving/planner/standard/openai/responses/plans.rs

@@ -57,6 +57,7 @@ pub(super) async fn build_local_sync_attempt_source<'a>(
     let spec_metadata = local_openai_responses_spec_metadata(spec);
     let Some(input) = resolve_local_openai_responses_decision_input(
         state,
+        parts,
         trace_id,
         decision,
         body_json,
@@ -108,6 +109,7 @@ pub(super) async fn build_local_stream_attempt_source<'a>(
     let spec_metadata = local_openai_responses_spec_metadata(spec);
     let Some(input) = resolve_local_openai_responses_decision_input(
         state,
+        parts,
         trace_id,
         decision,
         body_json,
@@ -291,6 +293,7 @@ pub(super) async fn build_local_sync_plan_and_reports(
     let spec_metadata = local_openai_responses_spec_metadata(spec);
     let Some(input) = resolve_local_openai_responses_decision_input(
         state,
+        parts,
         trace_id,
         decision,
         body_json,
@@ -362,6 +365,7 @@ pub(super) async fn build_local_stream_plan_and_reports(
     let spec_metadata = local_openai_responses_spec_metadata(spec);
     let Some(input) = resolve_local_openai_responses_decision_input(
         state,
+        parts,
         trace_id,
         decision,
         body_json,