feat(ai): AgentTool trait + ToolRegistry + AgentOrchestrator — ReAct 循环（最多 5 轮 Tool Call）

crates/erp-ai/src/agent/orchestrator.rs

@@ -0,0 +1,117 @@
+use std::sync::Arc;
+
+use super::registry::ToolRegistry;
+use super::tool::ToolContext;
+use crate::dto::{ChatMessage, ChatMessageRole};
+use crate::error::AiResult;
+use crate::provider::AiProvider;
+
+/// Agent Orchestrator — 执行 ReAct 循环
+pub struct AgentOrchestrator {
+    provider: Arc<dyn AiProvider>,
+    tool_registry: Arc<ToolRegistry>,
+    max_iterations: usize,
+}
+
+/// Agent 运行结果
+pub struct AgentRunResult {
+    pub reply: String,
+    pub total_input_tokens: u32,
+    pub total_output_tokens: u32,
+    pub iterations: usize,
+}
+
+impl AgentOrchestrator {
+    pub fn new(provider: Arc<dyn AiProvider>, tool_registry: Arc<ToolRegistry>) -> Self {
+        Self {
+            provider,
+            tool_registry,
+            max_iterations: 5,
+        }
+    }
+
+    /// 执行 Agent ReAct 循环
+    pub async fn run(
+        &self,
+        system_prompt: &str,
+        messages: &mut Vec<ChatMessage>,
+        ctx: &ToolContext,
+    ) -> AiResult<AgentRunResult> {
+        let tools = self.tool_registry.tool_definitions();
+        let mut iterations = 0;
+        let mut total_input_tokens = 0u32;
+        let mut total_output_tokens = 0u32;
+
+        loop {
+            iterations += 1;
+
+            let response = self
+                .provider
+                .generate_with_tools(
+                    messages.clone(),
+                    tools.clone(),
+                    system_prompt,
+                    "auto",
+                    0.7,
+                    2048,
+                )
+                .await?;
+
+            if let Some(ref usage) = response.usage {
+                total_input_tokens += usage.input;
+                total_output_tokens += usage.output;
+            }
+
+            // 如果没有 tool_calls，Agent 给出最终回复
+            let tool_calls = match response.tool_calls {
+                Some(tc) if !tc.is_empty() => tc,
+                _ => {
+                    return Ok(AgentRunResult {
+                        reply: response.content.unwrap_or_default(),
+                        total_input_tokens,
+                        total_output_tokens,
+                        iterations,
+                    });
+                }
+            };
+
+            // 达到上限：强制结束
+            if iterations >= self.max_iterations {
+                messages.push(ChatMessage {
+                    role: ChatMessageRole::User,
+                    content: "（系统提示：已收集足够信息，请直接总结回复用户，不要再调用工具）"
+                        .to_string(),
+                    tool_calls: None,
+                    tool_call_id: None,
+                });
+                continue;
+            }
+
+            // 将 assistant 的 tool_calls 加入消息历史
+            messages.push(ChatMessage {
+                role: ChatMessageRole::Assistant,
+                content: response.content.unwrap_or_default(),
+                tool_calls: Some(tool_calls.clone()),
+                tool_call_id: None,
+            });
+
+            // 执行每个 Tool Call
+            for tc in &tool_calls {
+                let tool_result = match self.tool_registry.get(&tc.name) {
+                    Some(tool) => {
+                        let result = tool.execute(ctx, tc.arguments.clone()).await;
+                        result.output
+                    }
+                    None => format!("未知 Tool: {}", tc.name),
+                };
+
+                messages.push(ChatMessage {
+                    role: ChatMessageRole::Tool,
+                    content: tool_result,
+                    tool_calls: None,
+                    tool_call_id: Some(tc.id.clone()),
+                });
+            }
+        }
+    }
+}