fix(loop): 原生工具调用从 Response.ToolCalls 解码 + 逐次回填工具结果 — 修复工具消息无回复

- 根因: loop/agent.decodeToolCalls 只读 resp.Message.ToolCallName/resp.Content JSON信封, 从不看 api 原生解析出的 resp.ToolCalls(Anthropic tool_use / OpenAI tool_calls)
  → 模型返回 thinking+tool_use(无text) 被判定'无工具调用' → 空 Content 当最终 text → res.Text="" → no reply produced; 纯聊天消息不调工具直接出 text, 故表现为'部分消息无回复'
- agent/step.go: ToolCall 增 ID; ExtractToolCalls 导出并优先 resp.ToolCalls(保留原生id+归一化nil Args), 回落两旧约定
- loop/request.go: decodeToolCalls 委托 agent.ExtractToolCalls(流式/非流式共用)
- loop/tool_history.go(新): 原生批次回填 assistant tool_use + 带tool_use_id的tool_result; 旧JSON信封批次保持 RoleTool 纯文本(向后兼容)
- openai.go: tool_call parts 编成 tool_calls + tool_call_id
- 新增 native_toolcall_test + native_toolcall_http_test(httptest假Anthropic SSE: round1 tool_use(无text)→round2含tool_use_id/tool_result→res.Text非空)
- build/vet/test绿+交叉编译

internal/runtime/loop/native_toolcall_http_test.go

@@ -0,0 +1,110 @@
+package loop
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"sync"
+	"testing"
+
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/config"
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/agent"
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
+)
+
+// anthropicToolRoundSSE is a native Anthropic stream that thinks, then emits a
+// tool_use block with an empty text part — the exact shape that starved the old
+// loop (which only looked for a JSON envelope in Content).
+const anthropicToolRoundSSE = `data: {"type":"message_start","message":{"model":"m","usage":{"input_tokens":10}}}
+
+data: {"type":"content_block_start","index":0,"content_block":{"type":"thinking","thinking":""}}
+
+data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":"checking the clock"}}
+
+data: {"type":"content_block_stop","index":0}
+
+data: {"type":"content_block_start","index":1,"content_block":{"type":"tool_use","id":"toolu_1","name":"datetime","input":{}}}
+
+data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":"{\"timezone\":\"Asia/Shanghai\"}"}}
+
+data: {"type":"content_block_stop","index":1}
+
+data: {"type":"message_delta","delta":{"stop_reason":"tool_use"},"usage":{"output_tokens":20}}
+
+data: {"type":"message_stop"}
+
+`
+
+// anthropicTextRoundSSE is the follow-up stream: a plain text answer after the
+// tool result was fed back.
+const anthropicTextRoundSSE = `data: {"type":"message_start","message":{"model":"m","usage":{"input_tokens":30}}}
+
+data: {"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}
+
+data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"现在是 10:34。"}}
+
+data: {"type":"content_block_stop","index":0}
+
+data: {"type":"message_delta","delta":{"stop_reason":"end_turn"},"usage":{"output_tokens":8}}
+
+data: {"type":"message_stop"}
+
+`
+
+// TestRun_NativeToolCall_AnthropicAdapter_HTTP exercises the real loop path end
+// to end through the real AnthropicChatAdapter against a stub /v1/messages
+// server: round 1 streams a thinking + tool_use block with no text, the loop
+// must execute it and re-ask, and round 2 must carry the assistant tool_use turn
+// plus a correlated tool_result and return the model's text (not an empty reply).
+func TestRun_NativeToolCall_AnthropicAdapter_HTTP(t *testing.T) {
+	t.Parallel()
+	var mu sync.Mutex
+	round := 0
+	var secondBody string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		body, _ := io.ReadAll(r.Body)
+		mu.Lock()
+		round++
+		n := round
+		if n == 2 {
+			secondBody = string(body)
+		}
+		mu.Unlock()
+		w.Header().Set("Content-Type", "text/event-stream")
+		if n == 1 {
+			_, _ = io.WriteString(w, anthropicToolRoundSSE)
+			return
+		}
+		_, _ = io.WriteString(w, anthropicTextRoundSSE)
+	}))
+	t.Cleanup(srv.Close)
+
+	ad := model.NewAnthropicChat(config.LLMConfig{AnthropicBaseURL: srv.URL, AnthropicModel: "m"})
+	td := dispatcherWith(t, &mockTool{name: "datetime", result: map[string]any{"now": "2026-09-08 22:34:00"}})
+	ag, err := agent.New("你是昔涟。", td, nil, agent.WithModel(ad, nil))
+	if err != nil {
+		t.Fatalf("agent.New: %v", err)
+	}
+	l := New(Options{Agent: ag, MaxRounds: 8, OnStream: func(model.StreamEvent) {}})
+
+	res, err := l.Run(context.Background(), "sess", []model.Message{model.TextMessage(model.RoleUser, "瞅瞅当前系统时间是多少")})
+	if err != nil {
+		t.Fatalf("Run: %v", err)
+	}
+	if res.Text != "现在是 10:34。" {
+		t.Fatalf("Text = %q, want the follow-up answer (empty means the native tool call was dropped)", res.Text)
+	}
+	if res.ToolCallsExecuted != 1 {
+		t.Fatalf("ToolCallsExecuted = %d, want 1", res.ToolCallsExecuted)
+	}
+	if secondBody == "" {
+		t.Fatal("adapter never made a second request (tool result was not fed back)")
+	}
+	for _, want := range []string{`"type":"tool_use"`, `"id":"toolu_1"`, `"type":"tool_result"`, `"tool_use_id":"toolu_1"`} {
+		if !strings.Contains(secondBody, want) {
+			t.Fatalf("second request missing %s:\n%s", want, secondBody)
+		}
+	}
+}