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。

tools/read_page_test.go

@@ -0,0 +1,105 @@
+package tools
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func readIn(t *testing.T, input string, files map[string]string) (string, error) {
+	t.Helper()
+	dir := t.TempDir()
+	for name, content := range files {
+		p := filepath.Join(dir, name)
+		if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(p, []byte(content), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	reg := NewRegistry()
+	for _, tl := range BuiltinIn(dir, NewFence(), nil) {
+		if err := reg.Register(tl); err != nil {
+			t.Fatal(err)
+		}
+	}
+	r, _ := reg.Get("read")
+	res, err := r.Run(context.Background(), input)
+	return res.Text, err
+}
+
+// TestReadSmallFileUnchanged：不分页的小文件保持原样，不加头尾。
+func TestReadSmallFileUnchanged(t *testing.T) {
+	got, err := readIn(t, `{"path":"f.txt"}`, map[string]string{"f.txt": "a\nb\nc\n"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != "a\nb\nc\n" {
+		t.Fatalf("got %q", got)
+	}
+}
+
+func TestReadOffsetLimit(t *testing.T) {
+	got, err := readIn(t, `{"path":"f.txt","offset":2,"limit":2}`,
+		map[string]string{"f.txt": "l1\nl2\nl3\nl4\nl5\n"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(got, "lines 2-3 of 5") || !strings.Contains(got, "l2\nl3") {
+		t.Fatalf("got %q", got)
+	}
+	if !strings.Contains(got, "continue with offset: 4") {
+		t.Fatalf("missing continuation: %q", got)
+	}
+	if strings.Contains(got, "l1") || strings.Contains(got, "l4") {
+		t.Fatalf("paging leaked other lines: %q", got)
+	}
+}
+
+func TestReadBeyondEOF(t *testing.T) {
+	got, err := readIn(t, `{"path":"f.txt","offset":99}`, map[string]string{"f.txt": "a\nb\n"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(got, "beyond EOF") {
+		t.Fatalf("got %q", got)
+	}
+}
+
+func TestReadDirectoryListing(t *testing.T) {
+	got, err := readIn(t, `{"path":".","offset":2,"limit":1}`, map[string]string{
+		"a.txt":    "x",
+		"sub/b.go": "y",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(got, "entries 2-2 of 2") || !strings.Contains(got, "sub/") {
+		t.Fatalf("got %q", got)
+	}
+	if strings.Contains(got, "a.txt") {
+		t.Fatalf("paging leaked other entries: %q", got)
+	}
+}
+
+func TestReadRejectsBinary(t *testing.T) {
+	dir := t.TempDir()
+	p := filepath.Join(dir, "bin")
+	if err := os.WriteFile(p, []byte{'a', 0, 'b'}, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	reg := NewRegistry()
+	for _, tl := range BuiltinIn(dir, NewFence(), nil) {
+		if err := reg.Register(tl); err != nil {
+			t.Fatal(err)
+		}
+	}
+	r, _ := reg.Get("read")
+	if _, err := r.Run(context.Background(), `{"path":"bin"}`); err == nil ||
+		!strings.Contains(err.Error(), "binary") {
+		t.Fatalf("want binary error, got %v", err)
+	}
+}