runtime: add execution concurrency limits

apps/admin-api/src/service.rs

@@ -698,15 +698,32 @@ fn default_operation_category() -> String {
 }
 
 impl AdminService {
+    #[cfg(test)]
     pub fn new(
         registry: PostgresRegistry,
         storage_root: PathBuf,
         auth_settings: AuthSettings,
         secret_crypto: SecretCrypto,
+    ) -> Self {
+        Self::new_with_runtime(
+            registry,
+            storage_root,
+            auth_settings,
+            secret_crypto,
+            RuntimeExecutor::new(),
+        )
+    }
+
+    pub fn new_with_runtime(
+        registry: PostgresRegistry,
+        storage_root: PathBuf,
+        auth_settings: AuthSettings,
+        secret_crypto: SecretCrypto,
+        runtime: RuntimeExecutor,
     ) -> Self {
         Self {
             registry,
-            runtime: RuntimeExecutor::new(),
+            runtime,
             storage: LocalArtifactStorage::new(storage_root),
             auth_settings,
             secret_crypto,
@@ -4881,6 +4898,7 @@ fn runtime_error_code(error: &RuntimeError) -> &'static str {
         RuntimeError::SoapAdapter(_) => "soap_error",
         RuntimeError::WebsocketAdapter(_) => "websocket_error",
         RuntimeError::UnsupportedProtocol { .. } => "unsupported_protocol",
+        RuntimeError::ConcurrencyLimitExceeded { .. } => "runtime_overloaded",
         RuntimeError::MissingStreamingConfig { .. } => "streaming_config_error",
         RuntimeError::UnsupportedExecutionMode { .. } => "streaming_mode_error",
         RuntimeError::InvalidStreamingPayload { .. } => "streaming_payload_error",