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/handlers/admin/provider/pool_admin/payloads.rs

@@ -10,6 +10,11 @@ use crate::provider_key_auth::{
 };
 use aether_admin::provider::pool as admin_provider_pool_pure;
 use aether_admin::provider::quota as admin_provider_quota_pure;
+use aether_admin::provider::redaction::{
+    admin_provider_metadata_bucket_safe_json, admin_provider_oauth_invalid_reason_safe_text,
+    admin_provider_status_snapshot_safe_json, admin_provider_upstream_metadata_safe_json,
+    admin_secret_safe_json, admin_secret_safe_proxy,
+};
 use aether_data_contracts::repository::pool_scores::StoredPoolMemberScore;
 use aether_data_contracts::repository::provider_catalog::{
     StoredProviderCatalogEndpoint, StoredProviderCatalogKey,
@@ -46,6 +51,14 @@ fn admin_pool_json_object(
         .filter(|value| !value.is_empty())
 }
 
+fn admin_pool_secret_safe_json_object(value: Option<&serde_json::Value>) -> serde_json::Value {
+    admin_pool_json_object(value)
+        .map(serde_json::Value::Object)
+        .as_ref()
+        .map(|value| admin_secret_safe_json(Some(value)))
+        .unwrap_or(serde_json::Value::Null)
+}
+
 fn admin_pool_json_to_f64(value: Option<&serde_json::Value>) -> Option<f64> {
     let parsed = match value {
         Some(serde_json::Value::Number(number)) => number.as_f64(),
@@ -1087,7 +1100,10 @@ pub(super) fn build_admin_pool_key_payload(
     codex_cycle_usage_by_code: Option<&BTreeMap<String, StoredProviderApiKeyWindowUsageSummary>>,
     now_unix_secs: u64,
 ) -> serde_json::Value {
-    let cooldown_reason = runtime.cooldown_reason_by_key.get(&key.id).cloned();
+    let cooldown_reason = runtime
+        .cooldown_reason_by_key
+        .get(&key.id)
+        .map(|_| "Provider key is cooling down".to_string());
     let cooldown_ttl_seconds = cooldown_reason
         .as_ref()
         .and_then(|_| runtime.cooldown_ttl_by_key.get(&key.id).copied());
@@ -1251,7 +1267,9 @@ pub(super) fn build_admin_pool_key_payload(
         "oauth_invalid_reason".to_string(),
         json!(auth_semantics
             .can_show_oauth_metadata()
-            .then_some(key.oauth_invalid_reason.clone())
+            .then(|| {
+                admin_provider_oauth_invalid_reason_safe_text(key.oauth_invalid_reason.as_deref())
+            })
             .flatten()),
     );
     payload.insert("oauth_plan_type".to_string(), json!(oauth_plan_type));
@@ -1290,7 +1308,10 @@ pub(super) fn build_admin_pool_key_payload(
         "account_status_source".to_string(),
         json!(account_status_source),
     );
-    payload.insert("status_snapshot".to_string(), status_snapshot);
+    payload.insert(
+        "status_snapshot".to_string(),
+        admin_provider_status_snapshot_safe_json(Some(&status_snapshot)),
+    );
     payload.insert("quota_updated_at".to_string(), json!(quota_updated_at));
     payload.insert("health_score".to_string(), json!(health_score));
     payload.insert(
@@ -1305,7 +1326,10 @@ pub(super) fn build_admin_pool_key_payload(
                     "score": score.score,
                     "hard_state": score.hard_state.as_database(),
                     "score_version": score.score_version,
-                    "score_reason": score.score_reason.clone(),
+                    "score_reason": admin_provider_metadata_bucket_safe_json(
+                        "pool_score",
+                        Some(&score.score_reason),
+                    ),
                     "last_ranked_at": score.last_ranked_at,
                     "last_scheduled_at": score.last_scheduled_at,
                     "last_success_at": score.last_success_at,
@@ -1335,7 +1359,7 @@ pub(super) fn build_admin_pool_key_payload(
     );
     payload.insert(
         "rate_multipliers".to_string(),
-        json!(admin_pool_json_object(key.rate_multipliers.as_ref())),
+        admin_pool_secret_safe_json_object(key.rate_multipliers.as_ref()),
     );
     payload.insert(
         "internal_priority".to_string(),
@@ -1358,7 +1382,7 @@ pub(super) fn build_admin_pool_key_payload(
     );
     payload.insert(
         "capabilities".to_string(),
-        json!(admin_pool_json_object(key.capabilities.as_ref())),
+        admin_pool_secret_safe_json_object(key.capabilities.as_ref()),
     );
     payload.insert(
         "auto_fetch_models".to_string(),
@@ -1378,10 +1402,16 @@ pub(super) fn build_admin_pool_key_payload(
     );
     payload.insert(
         "upstream_metadata".to_string(),
-        json!(key.upstream_metadata.clone()),
+        admin_provider_upstream_metadata_safe_json(key.upstream_metadata.as_ref()),
+    );
+    payload.insert(
+        "proxy".to_string(),
+        admin_secret_safe_proxy(key.proxy.as_ref()),
+    );
+    payload.insert(
+        "fingerprint".to_string(),
+        admin_secret_safe_json(key.fingerprint.as_ref()),
     );
-    payload.insert("proxy".to_string(), json!(key.proxy.clone()));
-    payload.insert("fingerprint".to_string(), json!(key.fingerprint.clone()));
     payload.insert("account_quota".to_string(), json!(account_quota));
     payload.insert("cooldown_reason".to_string(), json!(cooldown_reason));
     payload.insert(