fix(transport): preserve safe accept encoding

apps/aether-gateway/src/execution_runtime/sync/execution/policy.rs

@@ -16,6 +16,8 @@ pub(super) fn decode_execution_result_body(
     };
 
     if let Some(json_body) = body.json_body {
+        remove_header_case_insensitive(headers, "content-encoding");
+        remove_header_case_insensitive(headers, "content-length");
         headers
             .entry("content-type".to_string())
             .or_insert_with(|| "application/json".to_string());
@@ -34,3 +36,49 @@ pub(super) fn decode_execution_result_body(
 
     Ok((Vec::new(), None, None))
 }
+
+fn remove_header_case_insensitive(headers: &mut BTreeMap<String, String>, name: &str) {
+    if let Some(existing_key) = headers
+        .keys()
+        .find(|key| key.eq_ignore_ascii_case(name))
+        .cloned()
+    {
+        headers.remove(&existing_key);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::collections::BTreeMap;
+
+    use aether_contracts::ResponseBody;
+    use serde_json::json;
+
+    use super::decode_execution_result_body;
+
+    #[test]
+    fn decoded_json_body_drops_stale_content_encoding_headers() {
+        let mut headers = BTreeMap::from([
+            ("content-encoding".to_string(), "gzip".to_string()),
+            ("content-length".to_string(), "999".to_string()),
+        ]);
+
+        let (body_bytes, body_json, body_base64) = decode_execution_result_body(
+            Some(ResponseBody {
+                json_body: Some(json!({"ok": true})),
+                body_bytes_b64: None,
+            }),
+            &mut headers,
+        )
+        .expect("body should decode");
+
+        assert_eq!(body_json, Some(json!({"ok": true})));
+        assert_eq!(body_base64, None);
+        assert_eq!(body_bytes, br#"{"ok":true}"#);
+        assert_eq!(headers.get("content-encoding"), None);
+        assert_eq!(
+            headers.get("content-length").cloned(),
+            Some(body_bytes.len().to_string())
+        );
+    }
+}