Harden PII redaction format conversion

apps/aether-gateway/src/ai_serving/planner/redaction.rs

@@ -29,7 +29,6 @@ impl<'a> ProviderRequestRedaction<'a> {
 #[derive(Clone, Copy, Debug, Default)]
 struct ChatPiiRedactionFeatureSettings {
     enabled: Option<bool>,
-    inject_model_instruction: Option<bool>,
 }
 
 impl ChatPiiRedactionFeatureSettings {
@@ -44,21 +43,11 @@ impl ChatPiiRedactionFeatureSettings {
         if let Some(enabled) = settings.get("enabled").and_then(Value::as_bool) {
             self.enabled = Some(enabled);
         }
-        if let Some(inject_model_instruction) = settings
-            .get("inject_model_instruction")
-            .and_then(Value::as_bool)
-        {
-            self.inject_model_instruction = Some(inject_model_instruction);
-        }
     }
 
     fn effective_enabled(self) -> bool {
         self.enabled.unwrap_or(false)
     }
-
-    fn effective_inject_model_instruction(self) -> bool {
-        self.inject_model_instruction.unwrap_or(true)
-    }
 }
 
 pub(crate) fn request_identity_response_encoding_when_redacted(
@@ -122,7 +111,7 @@ pub(crate) async fn resolve_provider_chat_pii_redaction<'a>(
         &body_bytes,
         format,
         build_redaction_session_config(hmac_key, &runtime_config, now_unix_secs),
-        MaskChatRequestOptions::runtime(feature_settings.effective_inject_model_instruction()),
+        MaskChatRequestOptions::runtime(),
         Some(&cache),
     )
     .await
@@ -190,3 +179,22 @@ fn redaction_mask_error_to_gateway_error(error: RedactionMaskError) -> GatewayEr
         },
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use serde_json::json;
+
+    use super::ChatPiiRedactionFeatureSettings;
+
+    #[test]
+    fn chat_pii_redaction_feature_settings_only_control_enablement() {
+        let mut settings = ChatPiiRedactionFeatureSettings::default();
+        settings.merge_from_value(Some(&json!({
+            "chat_pii_redaction": {
+                "enabled": true
+            }
+        })));
+
+        assert!(settings.effective_enabled());
+    }
+}

apps/aether-gateway/src/ai_serving/planner/standard/codex/tests.rs

@@ -3,6 +3,7 @@ use std::collections::BTreeMap;
 use super::{
     apply_codex_openai_responses_special_body_edits, apply_codex_openai_responses_special_headers,
 };
+use crate::ai_serving::planner::standard::build_local_openai_responses_request_body;
 use http::{HeaderMap, HeaderValue};
 use serde_json::json;
 
@@ -36,6 +37,40 @@ fn applies_codex_defaults_when_body_rules_do_not_handle_fields() {
     assert!(body.get("reasoning").is_none());
 }
 
+#[test]
+fn local_openai_responses_codex_body_wraps_string_input_for_backend() {
+    let body = json!({
+        "model": "gpt-5",
+        "input": "hello"
+    });
+
+    let provider_request_body = build_local_openai_responses_request_body(
+        &body,
+        "gpt-5-upstream",
+        false,
+        false,
+        "codex",
+        "openai:responses",
+        None,
+        Some("key-123"),
+        &HeaderMap::new(),
+        false,
+    )
+    .expect("codex local openai responses body should build");
+
+    assert_eq!(
+        provider_request_body["input"],
+        json!([{
+            "type": "message",
+            "role": "user",
+            "content": [{
+                "type": "input_text",
+                "text": "hello"
+            }]
+        }])
+    );
+}
+
 #[test]
 fn strips_store_for_compact_even_when_body_rules_handle_it() {
     let body_rules = json!([