feat(security): harden gateway boundaries and usage policies

Consolidate subscription usage policy enforcement, privacy-safe persistence, and gateway security hardening into one reviewable change.

Includes bounded HTTP and execution envelopes, header and protocol guards, DNS and relay validation, authentication and secret projection hardening, secure backup/install paths, and regression coverage.

apps/aether-gateway/src/audit/admin.rs

@@ -34,6 +34,7 @@ pub(crate) fn emit_admin_audit(
     path_and_query: &str,
     control_decision: Option<&GatewayControlDecision>,
 ) {
+    let sanitized_path_and_query = sanitize_admin_audit_path(path_and_query);
     let Some(decision) = control_decision else {
         return;
     };
@@ -64,9 +65,10 @@ pub(crate) fn emit_admin_audit(
             },
             route_kind,
             default_target_type(route_family),
-            path_and_query.to_string(),
+            sanitized_path_and_query.clone(),
         )
     };
+    let target_id = sanitize_admin_audit_target_id(target_id);
 
     let (audit_status, log_level) = classify_admin_audit_response(method, response.status());
     if log_level == AdminAuditLogLevel::Info {
@@ -83,7 +85,7 @@ pub(crate) fn emit_admin_audit(
             route_family,
             route_kind,
             method = %method,
-            path = %path_and_query,
+            path = %sanitized_path_and_query,
             action,
             target_type,
             target_id = %target_id,
@@ -103,7 +105,7 @@ pub(crate) fn emit_admin_audit(
             route_family,
             route_kind,
             method = %method,
-            path = %path_and_query,
+            path = %sanitized_path_and_query,
             action,
             target_type,
             target_id = %target_id,
@@ -112,6 +114,17 @@ pub(crate) fn emit_admin_audit(
     }
 }
 
+fn sanitize_admin_audit_path(path_and_query: &str) -> String {
+    crate::middleware::sanitize_access_log_path(path_and_query)
+}
+
+fn sanitize_admin_audit_target_id(target_id: String) -> String {
+    if target_id.trim_start().starts_with('/') {
+        return sanitize_admin_audit_path(&target_id);
+    }
+    target_id
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 enum AdminAuditLogLevel {
     Info,
@@ -151,7 +164,10 @@ fn is_admin_read_method(method: &http::Method) -> bool {
 
 #[cfg(test)]
 mod tests {
-    use super::{classify_admin_audit_response, AdminAuditLogLevel};
+    use super::{
+        classify_admin_audit_response, sanitize_admin_audit_path, sanitize_admin_audit_target_id,
+        AdminAuditLogLevel,
+    };
     use axum::http::{Method, StatusCode};
 
     #[test]
@@ -169,4 +185,32 @@ mod tests {
             ("failed", AdminAuditLogLevel::Warn)
         );
     }
+
+    #[test]
+    fn audit_paths_drop_sensitive_query_values() {
+        assert_eq!(
+            sanitize_admin_audit_path(
+                "/api/admin/providers?token=secret&api_key=live-key&limit=25"
+            ),
+            "/api/admin/providers?limit=25"
+        );
+        assert_eq!(
+            sanitize_admin_audit_path("/install/one-time-secret?view=raw"),
+            "/install/[redacted]?view=raw"
+        );
+    }
+
+    #[test]
+    fn path_shaped_audit_targets_drop_sensitive_query_values() {
+        assert_eq!(
+            sanitize_admin_audit_target_id(
+                "/api/admin/monitoring/trace/request-1?token=secret&limit=25".to_string(),
+            ),
+            "/api/admin/monitoring/trace/request-1?limit=25"
+        );
+        assert_eq!(
+            sanitize_admin_audit_target_id("resource-id?literal".to_string()),
+            "resource-id?literal"
+        );
+    }
 }

apps/aether-gateway/src/audit/http.rs

@@ -26,7 +26,10 @@ pub(crate) async fn get_request_candidate_trace(
         .map_err(|err| GatewayError::Internal(err.to_string()).into_response())?;
 
     match trace {
-        Some(trace) => Ok(Json(trace)),
+        Some(mut trace) => {
+            trace.sanitize_sensitive_diagnostics();
+            Ok(Json(trace))
+        }
         None => Err((
             axum::http::StatusCode::NOT_FOUND,
             Json(json!({
@@ -52,7 +55,10 @@ pub(crate) async fn get_decision_trace(
         .map_err(|err| GatewayError::Internal(err.to_string()).into_response())?;
 
     match trace {
-        Some(trace) => Ok(Json(trace)),
+        Some(mut trace) => {
+            trace.sanitize_sensitive_diagnostics();
+            Ok(Json(trace))
+        }
         None => Err((
             axum::http::StatusCode::NOT_FOUND,
             Json(json!({