feat: AutoZero 通用 Agent 框架（从 AutoGo 五阶段拆分完成）

llm（三协议 Provider）/ session（JSONL 持久化）/ tools（Registry、围栏、
builtin、computer）/ cdp（browser）/ skills / mcp / agent（循环、两级压缩、
编排、审批门控）+ 底座 jsonl/textx/execx/diag/scratch/spill/imagecache。

产品装配代码（config 桥接、schedule 工具、memory/plan/retro/prompt）
留在 AutoGo，宿主接入方式见 MIGRATION.md。

agent/trace_test.go

@@ -0,0 +1,175 @@
+package agent
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"git.gopher.ink/mirrors2/AutoZero/llm"
+	"git.gopher.ink/mirrors2/AutoZero/session"
+	"git.gopher.ink/mirrors2/AutoZero/tools"
+)
+
+// TestModelCallTrace：每轮模型调用都应记录 StartedAt/DurationMs/Step。
+func TestModelCallTrace(t *testing.T) {
+	prov := &scriptedProvider{fn: func(_ int, _ string, _ []llm.Message, _ []llm.ToolDef) (llm.Message, error) {
+		time.Sleep(6 * time.Millisecond)
+		return llm.Message{Role: llm.RoleAssistant, Content: "done"}, nil
+	}}
+	a := &Agent{
+		Provider: prov,
+		Tools:    tools.NewRegistry(),
+		Session:  &session.Session{},
+		System:   "sys",
+		Opt:      Options{Stdout: io.Discard, Stderr: io.Discard},
+	}
+	if err := a.Run(context.Background(), "hi"); err != nil {
+		t.Fatal(err)
+	}
+	msgs := a.Session.Messages
+	last := msgs[len(msgs)-1]
+	if last.Role != llm.RoleAssistant {
+		t.Fatalf("last message should be assistant, got %s", last.Role)
+	}
+	if last.StartedAt == 0 {
+		t.Error("assistant StartedAt not recorded")
+	}
+	if last.DurationMs < 5 {
+		t.Errorf("assistant DurationMs = %d, want >= 5", last.DurationMs)
+	}
+	if last.Step != 1 {
+		t.Errorf("assistant Step = %d, want 1", last.Step)
+	}
+}
+
+// slowTool 是一个可计时的假工具，delay 控制耗时。
+func slowTool(name string, ro, safe bool, delay time.Duration) *tools.Tool {
+	return &tools.Tool{
+		Name:            name,
+		Parameters:      map[string]any{"type": "object"},
+		ReadOnly:        ro,
+		ConcurrencySafe: safe,
+		Run: func(_ context.Context, _ string) (tools.Result, error) {
+			time.Sleep(delay)
+			return tools.TextResult("ok"), nil
+		},
+	}
+}
+
+// toolMsgFor 取某次工具调用的回填消息。
+func toolMsgFor(sess *session.Session, id string) (llm.Message, bool) {
+	for _, m := range sess.Messages {
+		if m.Role == llm.RoleTool && m.ToolCallID == id {
+			return m, true
+		}
+	}
+	return llm.Message{}, false
+}
+
+// TestToolCallTrace：工具耗时与所属轮次写进 tool 消息，且 done 事件带耗时。
+func TestToolCallTrace(t *testing.T) {
+	a, sess := newTestAgent(t, slowTool("slow", false, false, 6*time.Millisecond))
+	a.curStep = 3 // 模拟处于第 3 次模型调用
+
+	var events []ToolEvent
+	a.Opt.OnTool = func(ev ToolEvent) { events = append(events, ev) }
+
+	if err := a.execTools(context.Background(), []llm.ToolCall{{ID: "c1", Name: "slow", Input: "{}"}}); err != nil {
+		t.Fatal(err)
+	}
+
+	msg, ok := toolMsgFor(sess, "c1")
+	if !ok {
+		t.Fatal("tool result message not appended")
+	}
+	if msg.StartedAt == 0 || msg.DurationMs < 5 {
+		t.Errorf("tool trace missing: %+v", msg)
+	}
+	if msg.Step != 3 {
+		t.Errorf("tool Step = %d, want 3 (parent turn)", msg.Step)
+	}
+
+	// done 事件应带耗时（供实时 UI 使用）。
+	var done *ToolEvent
+	for i := range events {
+		if events[i].ID == "c1" && events[i].Done {
+			done = &events[i]
+		}
+	}
+	if done == nil {
+		t.Fatal("no done event for c1")
+	}
+	if done.DurationMs < 5 || done.StartedAt == 0 {
+		t.Errorf("done event missing trace: %+v", *done)
+	}
+}
+
+// TestConcurrentToolTraceAttribution：并发批次的耗时按各自索引归属，不串号。
+func TestConcurrentToolTraceAttribution(t *testing.T) {
+	a, sess := newTestAgent(t,
+		slowTool("fast", true, true, 5*time.Millisecond),
+		slowTool("slowish", true, true, 30*time.Millisecond),
+	)
+	calls := []llm.ToolCall{
+		{ID: "c1", Name: "fast", Input: "{}"},
+		{ID: "c2", Name: "slowish", Input: "{}"},
+	}
+	if err := a.execTools(context.Background(), calls); err != nil {
+		t.Fatal(err)
+	}
+	fast, _ := toolMsgFor(sess, "c1")
+	slowish, _ := toolMsgFor(sess, "c2")
+	if fast.DurationMs <= 0 || slowish.DurationMs <= 0 {
+		t.Fatalf("durations not recorded: fast=%d slowish=%d", fast.DurationMs, slowish.DurationMs)
+	}
+	if fast.DurationMs >= slowish.DurationMs {
+		t.Errorf("durations attributed to the wrong call: fast=%d slowish=%d", fast.DurationMs, slowish.DurationMs)
+	}
+}
+
+// TestModelIdentityStamped：assistant 消息落盘要带「协议 + 模型」归因戳，
+// 缓存明细也得跟着落进会话文件；没实现 Identifier 的 provider（测试替身）
+// 必须留空而不是炸掉。
+func TestModelIdentityStamped(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/event-stream")
+		io.WriteString(w, "data: {\"choices\":[{\"delta\":{\"content\":\"ok\"}}]}\n\n")
+		io.WriteString(w, "data: {\"choices\":[{\"finish_reason\":\"stop\"}],\"usage\":{\"prompt_tokens\":11,"+
+			"\"completion_tokens\":2,\"prompt_tokens_details\":{\"cached_tokens\":9}}}\n\n")
+		io.WriteString(w, "data: [DONE]\n\n")
+	}))
+	defer srv.Close()
+	t.Setenv("HOME", t.TempDir())
+
+	a := &Agent{
+		Provider: &llm.OpenAIProvider{BaseURL: srv.URL, APIKey: "k", Model: "gpt-test"},
+		Tools:    tools.NewRegistry(), Session: &session.Session{}, System: "sys",
+		Opt: Options{Stdout: io.Discard, Stderr: io.Discard},
+	}
+	if err := a.Run(context.Background(), "hi"); err != nil {
+		t.Fatal(err)
+	}
+	last := a.Session.Messages[len(a.Session.Messages)-1]
+	if last.Format != llm.FormatChatCompletions || last.Model != "gpt-test" {
+		t.Errorf("归因戳 = %q/%q, want chat_completions/gpt-test", last.Format, last.Model)
+	}
+	if last.Usage == nil || last.Usage.CacheReadTokens != 9 || last.Usage.InputTokens != 11 {
+		t.Errorf("明细没落到会话：%+v", last.Usage)
+	}
+
+	prov := &scriptedProvider{fn: func(_ int, _ string, _ []llm.Message, _ []llm.ToolDef) (llm.Message, error) {
+		return llm.Message{Role: llm.RoleAssistant, Content: "x"}, nil
+	}}
+	b := &Agent{Provider: prov, Tools: tools.NewRegistry(), Session: &session.Session{}, System: "sys",
+		Opt: Options{Stdout: io.Discard, Stderr: io.Discard}}
+	if err := b.Run(context.Background(), "hi"); err != nil {
+		t.Fatal(err)
+	}
+	end := b.Session.Messages[len(b.Session.Messages)-1]
+	if end.Format != "" || end.Model != "" {
+		t.Errorf("未实现 Identifier 时不该有戳：%q/%q", end.Format, end.Model)
+	}
+}