feat(flow): 改进 Rhai 脚本执行错误处理和前后端代码节点映射

- 修改 eval_rhai_expr_json 返回 Result 以提供错误信息
- 统一使用 unwrap_or_else 处理 Rhai 表达式执行错误
- 前后端代码节点类型映射支持 JavaScript 和 Rhai 语言
- 前端代码编辑器添加语言选择器
- 优化 WebSocket 错误处理和关闭逻辑

backend/src/flow/executors/condition.rs

@@ -166,7 +166,7 @@ pub(crate) fn resolve_value(ctx: &serde_json::Value, v: &serde_json::Value) -> R
         "expression" => {
             let expr = v.get("content").and_then(|x| x.as_str()).unwrap_or("");
             if expr.trim().is_empty() { return Ok(V::Null); }
-            Ok(crate::flow::engine::eval_rhai_expr_json(expr, ctx).unwrap_or(V::Null))
+            Ok(crate::flow::engine::eval_rhai_expr_json(expr, ctx).unwrap_or_else(|_| V::Null))
         }
         _ => Ok(V::Null),
     }

backend/src/flow/executors/script_rhai.rs

@@ -62,7 +62,7 @@ pub fn exec_rhai_file(node_id: &NodeId, path: &str, ctx: &mut Value) -> anyhow::
     let res = eval_rhai_expr_json(&wrapped, ctx);
     let dur_ms = start.elapsed().as_millis();
     match res {
-        Some(new_ctx) => {
+        Ok(new_ctx) => {
             let (added, removed, modified) = shallow_diff(&before_ctx, &new_ctx);
             *ctx = new_ctx;
             info!(target = "udmin.flow", node=%node_id.0, ms=%dur_ms, added=%added.len(), removed=%removed.len(), modified=%modified.len(), "script task: Rhai file executed and ctx updated");
@@ -70,8 +70,8 @@ pub fn exec_rhai_file(node_id: &NodeId, path: &str, ctx: &mut Value) -> anyhow::
                 debug!(target = "udmin.flow", node=%node_id.0, ?added, ?removed, ?modified, "script task: ctx shallow diff");
             }
         }
-        None => {
-            info!(target = "udmin.flow", node=%node_id.0, ms=%dur_ms, preview=%preview, "script task: Rhai file execution failed, ctx unchanged");
+        Err(err) => {
+            info!(target = "udmin.flow", node=%node_id.0, ms=%dur_ms, preview=%preview, err=%err, "script task: Rhai file execution failed, ctx unchanged");
         }
     }
     Ok(())
@@ -114,10 +114,10 @@ impl Executor for ScriptRhaiTask {
 
             let before_ctx = ctx.clone();
             let wrapped = format!("{{ {} ; ctx }}", script);
-            let res = super::super::engine::eval_rhai_expr_json(&wrapped, ctx);
+            let res = eval_rhai_expr_json(&wrapped, ctx);
             let dur_ms = start.elapsed().as_millis();
             match res {
-                Some(new_ctx) => {
+                Ok(new_ctx) => {
                     let (added, removed, modified) = shallow_diff(&before_ctx, &new_ctx);
                     *ctx = new_ctx;
                     info!(target = "udmin.flow", node=%node_id.0, ms=%dur_ms, added=%added.len(), removed=%removed.len(), modified=%modified.len(), "script_rhai task: inline executed and ctx updated");
@@ -125,8 +125,8 @@ impl Executor for ScriptRhaiTask {
                         debug!(target = "udmin.flow", node=%node_id.0, ?added, ?removed, ?modified, "script_rhai task: ctx shallow diff");
                     }
                 }
-                None => {
-                    info!(target = "udmin.flow", node=%node_id.0, ms=%dur_ms, preview=%script_preview, "script_rhai task: inline execution failed, ctx unchanged");
+                Err(err) => {
+                    info!(target = "udmin.flow", node=%node_id.0, ms=%dur_ms, preview=%script_preview, err=%err, "script_rhai task: inline execution failed, ctx unchanged");
                 }
             }
             return Ok(());

backend/src/flow/executors/variable.rs

@@ -56,7 +56,7 @@ fn resolve_assign_value(ctx: &Value, v: &Value) -> Value {
                 }
                 // ctx[...] / ctx. 前缀 -> 表达式求值
                 if s_trim.starts_with("ctx[") || s_trim.starts_with("ctx.") {
-                    return eval_rhai_expr_json(s_trim, ctx).unwrap_or(V::Null);
+                    return eval_rhai_expr_json(s_trim, ctx).unwrap_or_else(|_| V::Null);
                 }
             }
             v.get("content").cloned().unwrap_or(V::Null)
@@ -97,7 +97,7 @@ fn resolve_assign_value(ctx: &Value, v: &Value) -> Value {
         "expression" => {
             let expr = v.get("content").and_then(|x| x.as_str()).unwrap_or("");
             if expr.trim().is_empty() { return V::Null; }
-            eval_rhai_expr_json(expr, ctx).unwrap_or(V::Null)
+            eval_rhai_expr_json(expr, ctx).unwrap_or_else(|_| V::Null)
         }
         _ => {
             // fallback: if content exists, treat as constant