diff --git a/crates/erp-workflow/src/engine/executor.rs b/crates/erp-workflow/src/engine/executor.rs
index efc6cb6..9ab4889 100644
--- a/crates/erp-workflow/src/engine/executor.rs
+++ b/crates/erp-workflow/src/engine/executor.rs
@@ -627,3 +627,73 @@ impl FlowExecutor {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::dto::{EdgeDef, NodeDef, NodeType};
+
+    fn make_node(id: &str, node_type: NodeType) -> NodeDef {
+        NodeDef {
+            id: id.to_string(),
+            node_type,
+            name: id.to_string(),
+            assignee_id: None,
+            candidate_groups: None,
+            service_type: None,
+            service_config: None,
+            position: None,
+        }
+    }
+
+    fn make_edge(id: &str, source: &str, target: &str) -> EdgeDef {
+        EdgeDef {
+            id: id.to_string(),
+            source: source.to_string(),
+            target: target.to_string(),
+            condition: None,
+            label: None,
+        }
+    }
+
+    #[test]
+    fn test_is_join_gateway_with_multiple_incoming() {
+        let nodes = vec![
+            make_node("start", NodeType::StartEvent),
+            make_node("a", NodeType::UserTask),
+            make_node("b", NodeType::ServiceTask),
+            make_node("join", NodeType::ParallelGateway),
+            make_node("end", NodeType::EndEvent),
+        ];
+        let edges = vec![
+            make_edge("e1", "start", "a"),
+            make_edge("e2", "start", "b"),
+            make_edge("e3", "a", "join"),
+            make_edge("e4", "b", "join"),
+            make_edge("e5", "join", "end"),
+        ];
+        let graph = FlowGraph::build(&nodes, &edges);
+        assert!(FlowExecutor::is_join_gateway("join", &graph));
+    }
+
+    #[test]
+    fn test_is_not_join_gateway_single_incoming() {
+        let nodes = vec![
+            make_node("start", NodeType::StartEvent),
+            make_node("fork", NodeType::ParallelGateway),
+            make_node("end", NodeType::EndEvent),
+        ];
+        let edges = vec![
+            make_edge("e1", "start", "fork"),
+            make_edge("e2", "fork", "end"),
+        ];
+        let graph = FlowGraph::build(&nodes, &edges);
+        assert!(!FlowExecutor::is_join_gateway("fork", &graph));
+    }
+
+    #[test]
+    fn test_is_not_join_gateway_for_nonexistent_node() {
+        let graph = FlowGraph::build(&[], &[]);
+        assert!(!FlowExecutor::is_join_gateway("nonexistent", &graph));
+    }
+}
diff --git a/crates/erp-workflow/src/engine/expression.rs b/crates/erp-workflow/src/engine/expression.rs
index 79616ff..67514c0 100644
--- a/crates/erp-workflow/src/engine/expression.rs
+++ b/crates/erp-workflow/src/engine/expression.rs
@@ -328,4 +328,105 @@ mod tests {
         let result = ExpressionEvaluator::eval("justavariable", &vars);
         assert!(result.is_err());
     }
+
+    // ---- 扩展边界测试 ----
+
+    #[test]
+    fn test_less_or_equal() {
+        let vars = make_vars();
+        assert!(ExpressionEvaluator::eval("amount <= 1500", &vars).unwrap());
+        assert!(ExpressionEvaluator::eval("amount <= 2000", &vars).unwrap());
+        assert!(!ExpressionEvaluator::eval("amount <= 1000", &vars).unwrap());
+    }
+
+    #[test]
+    fn test_boolean_equality() {
+        let vars = make_vars();
+        assert!(ExpressionEvaluator::eval("active == true", &vars).unwrap());
+        assert!(!ExpressionEvaluator::eval("active == false", &vars).unwrap());
+    }
+
+    #[test]
+    fn test_string_literal_with_single_quotes() {
+        let vars = make_vars();
+        assert!(ExpressionEvaluator::eval("status == 'approved'", &vars).unwrap());
+    }
+
+    #[test]
+    fn test_float_comparison() {
+        let mut vars = HashMap::new();
+        vars.insert("temperature".to_string(), json!(36.5));
+        assert!(ExpressionEvaluator::eval("temperature >= 36.0", &vars).unwrap());
+        assert!(ExpressionEvaluator::eval("temperature < 37.0", &vars).unwrap());
+        assert!(!ExpressionEvaluator::eval("temperature > 37.5", &vars).unwrap());
+    }
+
+    #[test]
+    fn test_integer_float_cross_comparison() {
+        let mut vars = HashMap::new();
+        vars.insert("val".to_string(), json!(10));
+        assert!(ExpressionEvaluator::eval("val == 10.0", &vars).unwrap());
+        assert!(ExpressionEvaluator::eval("val >= 9.5", &vars).unwrap());
+    }
+
+    #[test]
+    fn test_string_comparison_lexicographic() {
+        let vars = make_vars();
+        // name = "Alice"
+        assert!(!ExpressionEvaluator::eval("name > \"Alice\"", &vars).unwrap());
+        assert!(ExpressionEvaluator::eval("name >= \"Alice\"", &vars).unwrap());
+        assert!(ExpressionEvaluator::eval("name < \"Bob\"", &vars).unwrap());
+        assert!(ExpressionEvaluator::eval("name == \"Alice\"", &vars).unwrap());
+    }
+
+    #[test]
+    fn test_compound_and_or() {
+        let vars = make_vars();
+        // amount > 1000 (true) && score > 80 (true) || amount > 3000 (false)
+        // OR 先绑定，所以是 amount>1000 && score>80 (true) || amount>3000 (false)
+        // 注意：当前实现从左到右先匹配 ||，所以实际解析为:
+        // amount > 1000 && score > 80 || amount > 3000
+        // find_logical_op 先找 || → split at ||
+        // left = "amount > 1000 && score > 80", right = "amount > 3000"
+        // left = true, right = false → true || false = true
+        assert!(ExpressionEvaluator::eval(
+            "amount > 1000 && score > 80 || amount > 3000", &vars
+        ).unwrap());
+    }
+
+    #[test]
+    fn test_compound_all_false() {
+        let vars = make_vars();
+        assert!(!ExpressionEvaluator::eval(
+            "amount > 2000 && score > 90", &vars
+        ).unwrap());
+    }
+
+    #[test]
+    fn test_number_not_equals() {
+        let vars = make_vars();
+        assert!(ExpressionEvaluator::eval("amount != 1000", &vars).unwrap());
+        assert!(!ExpressionEvaluator::eval("amount != 1500", &vars).unwrap());
+    }
+
+    #[test]
+    fn test_expression_with_extra_whitespace() {
+        let vars = make_vars();
+        assert!(ExpressionEvaluator::eval("  amount  >  1000  ", &vars).unwrap());
+    }
+
+    #[test]
+    fn test_unresolvable_variable_returns_error() {
+        let vars = HashMap::new();
+        let result = ExpressionEvaluator::eval("missing_var > 10", &vars);
+        assert!(result.is_err());
+        assert!(result.unwrap_err().to_string().contains("未知的变量"));
+    }
+
+    #[test]
+    fn test_empty_expression_returns_error() {
+        let vars = HashMap::new();
+        let result = ExpressionEvaluator::eval("", &vars);
+        assert!(result.is_err());
+    }
 }
diff --git a/crates/erp-workflow/src/engine/model.rs b/crates/erp-workflow/src/engine/model.rs
index 8a37b49..8b68434 100644
--- a/crates/erp-workflow/src/engine/model.rs
+++ b/crates/erp-workflow/src/engine/model.rs
@@ -125,3 +125,261 @@ impl FlowGraph {
             .unwrap_or_default()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::dto::{EdgeDef, NodeDef, NodeType};
+
+    fn make_node(id: &str, node_type: NodeType) -> NodeDef {
+        NodeDef {
+            id: id.to_string(),
+            node_type,
+            name: id.to_string(),
+            assignee_id: None,
+            candidate_groups: None,
+            service_type: None,
+            service_config: None,
+            position: None,
+        }
+    }
+
+    fn make_edge(id: &str, source: &str, target: &str) -> EdgeDef {
+        EdgeDef {
+            id: id.to_string(),
+            source: source.to_string(),
+            target: target.to_string(),
+            condition: None,
+            label: None,
+        }
+    }
+
+    // ---- build ----
+
+    #[test]
+    fn build_empty_graph() {
+        let graph = FlowGraph::build(&[], &[]);
+        assert!(graph.nodes.is_empty());
+        assert!(graph.edges.is_empty());
+        assert!(graph.start_node_id.is_none());
+        assert!(graph.end_node_ids.is_empty());
+    }
+
+    #[test]
+    fn build_identifies_start_and_end() {
+        let nodes = vec![
+            make_node("start", NodeType::StartEvent),
+            make_node("task1", NodeType::UserTask),
+            make_node("end", NodeType::EndEvent),
+        ];
+        let edges = vec![
+            make_edge("e1", "start", "task1"),
+            make_edge("e2", "task1", "end"),
+        ];
+
+        let graph = FlowGraph::build(&nodes, &edges);
+
+        assert_eq!(graph.start_node_id, Some("start".to_string()));
+        assert_eq!(graph.end_node_ids, vec!["end".to_string()]);
+        assert_eq!(graph.nodes.len(), 3);
+        assert_eq!(graph.edges.len(), 2);
+    }
+
+    #[test]
+    fn build_multiple_end_events() {
+        let nodes = vec![
+            make_node("start", NodeType::StartEvent),
+            make_node("gw", NodeType::ExclusiveGateway),
+            make_node("end1", NodeType::EndEvent),
+            make_node("end2", NodeType::EndEvent),
+        ];
+        let edges = vec![
+            make_edge("e1", "start", "gw"),
+            make_edge("e2", "gw", "end1"),
+            make_edge("e3", "gw", "end2"),
+        ];
+
+        let graph = FlowGraph::build(&nodes, &edges);
+
+        assert_eq!(graph.end_node_ids.len(), 2);
+        assert!(graph.end_node_ids.contains(&"end1".to_string()));
+        assert!(graph.end_node_ids.contains(&"end2".to_string()));
+    }
+
+    #[test]
+    fn build_copies_node_properties() {
+        let user_id = {
+            let ts = uuid::Timestamp::now(uuid::NoContext);
+            uuid::Uuid::new_v7(ts)
+        };
+        let nodes = vec![NodeDef {
+            id: "task".to_string(),
+            node_type: NodeType::UserTask,
+            name: "审批".to_string(),
+            assignee_id: Some(user_id),
+            candidate_groups: Some(vec!["managers".to_string()]),
+            service_type: None,
+            service_config: None,
+            position: None,
+        }];
+        let graph = FlowGraph::build(&nodes, &[]);
+
+        let node = graph.nodes.get("task").unwrap();
+        assert_eq!(node.name, "审批");
+        assert_eq!(node.assignee_id, Some(user_id));
+        assert_eq!(node.candidate_groups, Some(vec!["managers".to_string()]));
+    }
+
+    #[test]
+    fn build_edge_with_condition_and_label() {
+        let nodes = vec![
+            make_node("start", NodeType::StartEvent),
+            make_node("end", NodeType::EndEvent),
+        ];
+        let edges = vec![EdgeDef {
+            id: "e1".to_string(),
+            source: "start".to_string(),
+            target: "end".to_string(),
+            condition: Some("amount > 1000".to_string()),
+            label: Some("高额审批".to_string()),
+        }];
+
+        let graph = FlowGraph::build(&nodes, &edges);
+        let edge = graph.edges.get("e1").unwrap();
+        assert_eq!(edge.condition, Some("amount > 1000".to_string()));
+        assert_eq!(edge.label, Some("高额审批".to_string()));
+    }
+
+    #[test]
+    fn build_edge_to_unknown_node_still_recorded() {
+        let nodes = vec![make_node("start", NodeType::StartEvent)];
+        // edge target "missing" 不在 nodes 中，但 edge 仍被记录
+        let edges = vec![make_edge("e1", "start", "missing")];
+        let graph = FlowGraph::build(&nodes, &edges);
+
+        assert_eq!(graph.edges.len(), 1);
+        // outgoing 为 start 有 e1，但 incoming["missing"] 不存在
+        assert_eq!(graph.outgoing.get("start").unwrap().len(), 1);
+        assert!(graph.incoming.get("missing").is_none());
+    }
+
+    // ---- get_outgoing_edges ----
+
+    #[test]
+    fn outgoing_edges_for_known_node() {
+        let nodes = vec![
+            make_node("start", NodeType::StartEvent),
+            make_node("end", NodeType::EndEvent),
+        ];
+        let edges = vec![make_edge("e1", "start", "end")];
+        let graph = FlowGraph::build(&nodes, &edges);
+
+        let out = graph.get_outgoing_edges("start");
+        assert_eq!(out.len(), 1);
+        assert_eq!(out[0].target, "end");
+    }
+
+    #[test]
+    fn outgoing_edges_for_unknown_node_empty() {
+        let graph = FlowGraph::build(&[], &[]);
+        assert!(graph.get_outgoing_edges("nonexistent").is_empty());
+    }
+
+    #[test]
+    fn outgoing_edges_parallel_gateway_fan_out() {
+        let nodes = vec![
+            make_node("start", NodeType::StartEvent),
+            make_node("fork", NodeType::ParallelGateway),
+            make_node("a", NodeType::UserTask),
+            make_node("b", NodeType::ServiceTask),
+            make_node("end", NodeType::EndEvent),
+        ];
+        let edges = vec![
+            make_edge("e1", "start", "fork"),
+            make_edge("e2", "fork", "a"),
+            make_edge("e3", "fork", "b"),
+        ];
+        let graph = FlowGraph::build(&nodes, &edges);
+
+        let out = graph.get_outgoing_edges("fork");
+        assert_eq!(out.len(), 2);
+        let targets: Vec<&str> = out.iter().map(|e| e.target.as_str()).collect();
+        assert!(targets.contains(&"a"));
+        assert!(targets.contains(&"b"));
+    }
+
+    // ---- get_incoming_edges ----
+
+    #[test]
+    fn incoming_edges_for_known_node() {
+        let nodes = vec![
+            make_node("start", NodeType::StartEvent),
+            make_node("end", NodeType::EndEvent),
+        ];
+        let edges = vec![make_edge("e1", "start", "end")];
+        let graph = FlowGraph::build(&nodes, &edges);
+
+        let inc = graph.get_incoming_edges("end");
+        assert_eq!(inc.len(), 1);
+        assert_eq!(inc[0].source, "start");
+    }
+
+    #[test]
+    fn incoming_edges_for_unknown_node_empty() {
+        let graph = FlowGraph::build(&[], &[]);
+        assert!(graph.get_incoming_edges("nonexistent").is_empty());
+    }
+
+    #[test]
+    fn incoming_edges_join_gateway() {
+        let nodes = vec![
+            make_node("start", NodeType::StartEvent),
+            make_node("a", NodeType::UserTask),
+            make_node("b", NodeType::ServiceTask),
+            make_node("join", NodeType::ParallelGateway),
+            make_node("end", NodeType::EndEvent),
+        ];
+        let edges = vec![
+            make_edge("e1", "start", "a"),
+            make_edge("e2", "start", "b"),
+            make_edge("e3", "a", "join"),
+            make_edge("e4", "b", "join"),
+            make_edge("e5", "join", "end"),
+        ];
+        let graph = FlowGraph::build(&nodes, &edges);
+
+        let inc = graph.get_incoming_edges("join");
+        assert_eq!(inc.len(), 2);
+        let sources: Vec<&str> = inc.iter().map(|e| e.source.as_str()).collect();
+        assert!(sources.contains(&"a"));
+        assert!(sources.contains(&"b"));
+    }
+
+    // ---- start/end 节点无入/出边 ----
+
+    #[test]
+    fn start_node_has_no_incoming() {
+        let nodes = vec![
+            make_node("start", NodeType::StartEvent),
+            make_node("end", NodeType::EndEvent),
+        ];
+        let edges = vec![make_edge("e1", "start", "end")];
+        let graph = FlowGraph::build(&nodes, &edges);
+
+        assert!(graph.get_incoming_edges("start").is_empty());
+        assert_eq!(graph.get_outgoing_edges("start").len(), 1);
+    }
+
+    #[test]
+    fn end_node_has_no_outgoing() {
+        let nodes = vec![
+            make_node("start", NodeType::StartEvent),
+            make_node("end", NodeType::EndEvent),
+        ];
+        let edges = vec![make_edge("e1", "start", "end")];
+        let graph = FlowGraph::build(&nodes, &edges);
+
+        assert!(graph.get_outgoing_edges("end").is_empty());
+        assert_eq!(graph.get_incoming_edges("end").len(), 1);
+    }
+}
diff --git a/crates/erp-workflow/src/engine/parser.rs b/crates/erp-workflow/src/engine/parser.rs
index 8bdd2af..0b525dd 100644
--- a/crates/erp-workflow/src/engine/parser.rs
+++ b/crates/erp-workflow/src/engine/parser.rs
@@ -266,4 +266,233 @@ mod tests {
         let result = parse_and_validate(&nodes, &edges);
         assert!(result.is_err());
     }
+
+    // ---- 边界测试扩展 ----
+
+    #[test]
+    fn test_empty_nodes_rejected() {
+        let result = parse_and_validate(&[], &[]);
+        assert!(result.is_err());
+        let msg = result.unwrap_err().to_string();
+        assert!(msg.contains("不能为空"));
+    }
+
+    #[test]
+    fn test_multiple_start_events_rejected() {
+        let nodes = vec![
+            make_start(),
+            NodeDef {
+                id: "start2".to_string(),
+                node_type: NodeType::StartEvent,
+                name: "开始2".to_string(),
+                assignee_id: None,
+                candidate_groups: None,
+                service_type: None,
+                service_config: None,
+                position: None,
+            },
+            make_end(),
+        ];
+        let edges = vec![
+            make_edge("e1", "start", "end"),
+            make_edge("e2", "start2", "end"),
+        ];
+        let result = parse_and_validate(&nodes, &edges);
+        assert!(result.is_err());
+        let msg = result.unwrap_err().to_string();
+        assert!(msg.contains("只能包含一个开始事件"));
+    }
+
+    #[test]
+    fn test_edge_references_nonexistent_source() {
+        let nodes = vec![make_start(), make_end()];
+        let edges = vec![
+            make_edge("e1", "ghost", "end"),
+        ];
+        let result = parse_and_validate(&nodes, &edges);
+        assert!(result.is_err());
+        let msg = result.unwrap_err().to_string();
+        assert!(msg.contains("源节点") && msg.contains("不存在"));
+    }
+
+    #[test]
+    fn test_edge_references_nonexistent_target() {
+        let nodes = vec![make_start(), make_end()];
+        let edges = vec![
+            make_edge("e1", "start", "ghost"),
+        ];
+        let result = parse_and_validate(&nodes, &edges);
+        assert!(result.is_err());
+        let msg = result.unwrap_err().to_string();
+        assert!(msg.contains("目标节点") && msg.contains("不存在"));
+    }
+
+    #[test]
+    fn test_start_event_with_incoming_edge_rejected() {
+        let nodes = vec![make_start(), make_end()];
+        let edges = vec![
+            make_edge("e1", "start", "end"),
+            make_edge("e2", "end", "start"), // start 有入边
+        ];
+        let result = parse_and_validate(&nodes, &edges);
+        assert!(result.is_err());
+        let msg = result.unwrap_err().to_string();
+        assert!(msg.contains("入边"));
+    }
+
+    #[test]
+    fn test_start_event_without_outgoing_edge_rejected() {
+        let nodes = vec![make_start(), make_end()];
+        let edges = vec![]; // start 没有出边
+        let result = parse_and_validate(&nodes, &edges);
+        assert!(result.is_err());
+        let msg = result.unwrap_err().to_string();
+        assert!(msg.contains("出边"));
+    }
+
+    #[test]
+    fn test_exclusive_gateway_single_outgoing_ok() {
+        // 单条出边的排他网关不需要条件
+        let nodes = vec![
+            make_start(),
+            NodeDef {
+                id: "gw".to_string(),
+                node_type: NodeType::ExclusiveGateway,
+                name: "判断".to_string(),
+                assignee_id: None,
+                candidate_groups: None,
+                service_type: None,
+                service_config: None,
+                position: None,
+            },
+            make_end(),
+        ];
+        let edges = vec![
+            make_edge("e1", "start", "gw"),
+            make_edge("e2", "gw", "end"),
+        ];
+        assert!(parse_and_validate(&nodes, &edges).is_ok());
+    }
+
+    #[test]
+    fn test_exclusive_gateway_with_conditions_ok() {
+        let nodes = vec![
+            make_start(),
+            NodeDef {
+                id: "gw".to_string(),
+                node_type: NodeType::ExclusiveGateway,
+                name: "金额判断".to_string(),
+                assignee_id: None,
+                candidate_groups: None,
+                service_type: None,
+                service_config: None,
+                position: None,
+            },
+            make_user_task("task_a", "小额审批"),
+            make_user_task("task_b", "大额审批"),
+            make_end(),
+        ];
+        let edges = vec![
+            make_edge("e1", "start", "gw"),
+            EdgeDef {
+                id: "e2".to_string(),
+                source: "gw".to_string(),
+                target: "task_a".to_string(),
+                condition: Some("amount <= 1000".to_string()),
+                label: None,
+            },
+            EdgeDef {
+                id: "e3".to_string(),
+                source: "gw".to_string(),
+                target: "task_b".to_string(),
+                condition: Some("amount > 1000".to_string()),
+                label: None,
+            },
+            make_edge("e4", "task_a", "end"),
+            make_edge("e5", "task_b", "end"),
+        ];
+        assert!(parse_and_validate(&nodes, &edges).is_ok());
+    }
+
+    #[test]
+    fn test_gateway_without_incoming_rejected() {
+        let nodes = vec![
+            make_start(),
+            NodeDef {
+                id: "gw".to_string(),
+                node_type: NodeType::ParallelGateway,
+                name: "并行".to_string(),
+                assignee_id: None,
+                candidate_groups: None,
+                service_type: None,
+                service_config: None,
+                position: None,
+            },
+            make_end(),
+        ];
+        // gw 没有入边
+        let edges = vec![
+            make_edge("e1", "start", "end"),
+            make_edge("e2", "gw", "end"),
+        ];
+        let result = parse_and_validate(&nodes, &edges);
+        assert!(result.is_err());
+        let msg = result.unwrap_err().to_string();
+        assert!(msg.contains("入边"));
+    }
+
+    #[test]
+    fn test_gateway_without_outgoing_rejected() {
+        let nodes = vec![
+            make_start(),
+            NodeDef {
+                id: "gw".to_string(),
+                node_type: NodeType::ParallelGateway,
+                name: "并行".to_string(),
+                assignee_id: None,
+                candidate_groups: None,
+                service_type: None,
+                service_config: None,
+                position: None,
+            },
+            make_end(),
+        ];
+        // gw 没有出边
+        let edges = vec![
+            make_edge("e1", "start", "gw"),
+            make_edge("e2", "start", "end"),
+        ];
+        let result = parse_and_validate(&nodes, &edges);
+        assert!(result.is_err());
+        let msg = result.unwrap_err().to_string();
+        assert!(msg.contains("出边"));
+    }
+
+    #[test]
+    fn test_parallel_gateway_valid() {
+        let nodes = vec![
+            make_start(),
+            NodeDef {
+                id: "fork".to_string(),
+                node_type: NodeType::ParallelGateway,
+                name: "拆分".to_string(),
+                assignee_id: None,
+                candidate_groups: None,
+                service_type: None,
+                service_config: None,
+                position: None,
+            },
+            make_user_task("a", "任务A"),
+            make_user_task("b", "任务B"),
+            make_end(),
+        ];
+        let edges = vec![
+            make_edge("e1", "start", "fork"),
+            make_edge("e2", "fork", "a"),
+            make_edge("e3", "fork", "b"),
+            make_edge("e4", "a", "end"),
+            make_edge("e5", "b", "end"),
+        ];
+        assert!(parse_and_validate(&nodes, &edges).is_ok());
+    }
 }
diff --git a/crates/erp-workflow/src/error.rs b/crates/erp-workflow/src/error.rs
index 109cfa4..443c355 100644
--- a/crates/erp-workflow/src/error.rs
+++ b/crates/erp-workflow/src/error.rs
@@ -51,3 +51,78 @@ impl From<WorkflowError> for AppError {
 }
 
 pub type WorkflowResult<T> = Result<T, WorkflowError>;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn validation_maps_to_app_error_validation() {
+        let err = WorkflowError::Validation("字段缺失".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::Validation(msg) => assert!(msg.contains("字段缺失")),
+            other => panic!("期望 AppError::Validation，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn not_found_maps_to_app_error_not_found() {
+        let err = WorkflowError::NotFound("流程不存在".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::NotFound(msg) => assert!(msg.contains("流程不存在")),
+            other => panic!("期望 AppError::NotFound，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn duplicate_definition_maps_to_app_error_conflict() {
+        let err = WorkflowError::DuplicateDefinition("key 已存在".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::Conflict(msg) => assert!(msg.contains("key 已存在")),
+            other => panic!("期望 AppError::Conflict，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn invalid_diagram_maps_to_validation() {
+        let err = WorkflowError::InvalidDiagram("缺少 StartEvent".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::Validation(msg) => assert!(msg.contains("缺少 StartEvent")),
+            other => panic!("期望 AppError::Validation，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn invalid_state_maps_to_validation() {
+        let err = WorkflowError::InvalidState("流程已结束".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::Validation(msg) => assert!(msg.contains("流程已结束")),
+            other => panic!("期望 AppError::Validation，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn expression_error_maps_to_validation() {
+        let err = WorkflowError::ExpressionError("语法错误".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::Validation(msg) => assert!(msg.contains("语法错误")),
+            other => panic!("期望 AppError::Validation，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn version_mismatch_maps_directly() {
+        let err = WorkflowError::VersionMismatch;
+        let app: AppError = err.into();
+        match app {
+            AppError::VersionMismatch => {},
+            other => panic!("期望 AppError::VersionMismatch，得到 {:?}", other),
+        }
+    }
+}