feat(todo): 接入会话级 todo_write 工具链与上下文注入

internal/app/bootstrap.go

@@ -26,6 +26,7 @@ import (
 	"neo-code/internal/tools/filesystem"
 	"neo-code/internal/tools/mcp"
 	memotool "neo-code/internal/tools/memo"
+	"neo-code/internal/tools/todo"
 	"neo-code/internal/tools/webfetch"
 	"neo-code/internal/tui"
 )
@@ -244,6 +245,7 @@ func buildToolRegistry(cfg config.Config) (*tools.Registry, func() error, error)
 		MaxResponseBytes:      cfg.Tools.WebFetch.MaxResponseBytes,
 		SupportedContentTypes: cfg.Tools.WebFetch.SupportedContentTypes,
 	}))
+	toolRegistry.Register(todo.New())
 	mcpRegistry, err := buildMCPRegistry(cfg)
 	if err != nil {
 		return nil, nil, err

internal/context/builder.go

@@ -27,6 +27,7 @@ func NewBuilderWithToolPolicies(policies MicroCompactPolicySource) Builder {
 			corePromptSource{},
 			&projectRulesSource{},
 			taskStateSource{},
+			todosSource{},
 			skillPromptSource{},
 			systemSource,
 		},
@@ -43,6 +44,7 @@ func NewBuilderWithMemo(policies MicroCompactPolicySource, memoSource SectionSou
 		corePromptSource{},
 		&projectRulesSource{},
 		taskStateSource{},
+		todosSource{},
 		skillPromptSource{},
 	}
 	if memoSource != nil {

internal/context/builder_test.go

@@ -8,6 +8,7 @@ import (
 	"reflect"
 	"strings"
 	"testing"
+	"time"
 
 	"neo-code/internal/config"
 	"neo-code/internal/context/internalcompact"
@@ -142,6 +143,38 @@ func TestDefaultBuilderBuildIncludesTaskStateBeforeSystemState(t *testing.T) {
 	}
 }
 
+func TestDefaultBuilderBuildIncludesTodosBeforeSystemState(t *testing.T) {
+	t.Parallel()
+
+	builder := NewBuilder()
+	got, err := builder.Build(stdcontext.Background(), BuildInput{
+		Messages: []providertypes.Message{{Role: "user", Content: "hello"}},
+		Todos: []agentsession.TodoItem{
+			{
+				ID:        "todo-1",
+				Content:   "implement todo tool",
+				Status:    agentsession.TodoStatusInProgress,
+				Priority:  3,
+				Revision:  2,
+				CreatedAt: time.Now(),
+			},
+		},
+		Metadata: testMetadata(t.TempDir()),
+	})
+	if err != nil {
+		t.Fatalf("Build() error = %v", err)
+	}
+
+	todoIndex := strings.Index(got.SystemPrompt, "## Todo State")
+	systemStateIndex := strings.Index(got.SystemPrompt, "## System State")
+	if todoIndex < 0 || systemStateIndex < 0 {
+		t.Fatalf("expected todo and system sections, got %q", got.SystemPrompt)
+	}
+	if todoIndex > systemStateIndex {
+		t.Fatalf("expected todo section before system section, got %q", got.SystemPrompt)
+	}
+}
+
 func TestDefaultBuilderBuildUsesSpanTrimPolicyWhenTrimPolicyIsUnset(t *testing.T) {
 	t.Parallel()
 

internal/context/prompt.go

@@ -25,6 +25,7 @@ var defaultPromptSections = []promptSection{
 		Title: "Tool Usage",
 		Content: "- Use the minimum set of tools needed to make progress or verify a result safely.\n" +
 			"- Only call tools that are actually exposed in the current tool schema. Do not invent tool names.\n" +
+			"- For multi-step implementation work, keep task state explicit via `todo_write` (plan/add/update/set_status/claim/complete/fail) instead of relying on implicit memory.\n" +
 			"- Prefer structured workspace tools over `bash` whenever possible: use `filesystem_read_file`, `filesystem_grep`, and `filesystem_glob` for reading/search, `filesystem_edit` for precise edits, and `filesystem_write_file` only for new files or full rewrites.\n" +
 			"- Do not use `bash` to edit files when the filesystem tools can make the change safely.\n" +
 			"- When using `bash`, avoid interactive or blocking commands and pass non-interactive flags when they are available.\n" +

internal/context/prompt_test.go

@@ -117,6 +117,9 @@ func TestDefaultToolUsagePromptIncludesPermissionAndAntiLoopGuidance(t *testing.
 	if !strings.Contains(toolUsage, "Do not invent tool names") {
 		t.Fatalf("expected Tool Usage to forbid invented tool names, got %q", toolUsage)
 	}
+	if !strings.Contains(toolUsage, "`todo_write`") {
+		t.Fatalf("expected Tool Usage to mention todo_write for task state, got %q", toolUsage)
+	}
 	if !strings.Contains(toolUsage, "`filesystem_read_file`, `filesystem_grep`, and `filesystem_glob`") {
 		t.Fatalf("expected Tool Usage to prefer structured read/search tools, got %q", toolUsage)
 	}

internal/context/source_todos.go

@@ -0,0 +1,145 @@
+package context
+
+import (
+	"context"
+	"fmt"
+	"sort"
+	"strings"
+
+	agentsession "neo-code/internal/session"
+)
+
+const (
+	maxPromptTodos        = 24
+	maxPromptTodoIDLength = 80
+	maxPromptTodoTextLen  = 240
+	maxPromptTodoDeps     = 8
+	maxPromptOwnerLen     = 64
+)
+
+// todosSource 负责把会话 Todo 摘要渲染为 prompt section。
+type todosSource struct{}
+
+// Sections 渲染非终态 Todo，按状态与优先级排序后注入上下文。
+func (todosSource) Sections(ctx context.Context, input BuildInput) ([]promptSection, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	if len(input.Todos) == 0 {
+		return nil, nil
+	}
+
+	active := make([]agentsession.TodoItem, 0, len(input.Todos))
+	for _, item := range input.Todos {
+		if !item.Status.IsTerminal() {
+			active = append(active, item.Clone())
+		}
+	}
+	if len(active) == 0 {
+		return nil, nil
+	}
+
+	sort.SliceStable(active, func(i, j int) bool {
+		left := todoStatusRank(active[i].Status)
+		right := todoStatusRank(active[j].Status)
+		if left != right {
+			return left < right
+		}
+		if active[i].Priority != active[j].Priority {
+			return active[i].Priority > active[j].Priority
+		}
+		return active[i].CreatedAt.Before(active[j].CreatedAt)
+	})
+	if len(active) > maxPromptTodos {
+		active = active[:maxPromptTodos]
+	}
+
+	lines := make([]string, 0, len(active)+1)
+	for _, item := range active {
+		id := sanitizePromptValue(item.ID, maxPromptTodoIDLength)
+		content := sanitizePromptValue(item.Content, maxPromptTodoTextLen)
+		line := fmt.Sprintf("- [%s] id=%q (p=%d, rev=%d) content=%q", item.Status, id, item.Priority, item.Revision, content)
+		lines = append(lines, line)
+		if len(item.Dependencies) > 0 {
+			deps := sanitizePromptList(item.Dependencies, maxPromptTodoDeps, maxPromptTodoIDLength)
+			quotedDeps := make([]string, 0, len(deps))
+			for _, dep := range deps {
+				quotedDeps = append(quotedDeps, fmt.Sprintf("%q", dep))
+			}
+			lines = append(lines, fmt.Sprintf("  deps: %s", strings.Join(quotedDeps, ", ")))
+		}
+		if strings.TrimSpace(item.OwnerType) != "" || strings.TrimSpace(item.OwnerID) != "" {
+			ownerType := sanitizePromptValue(item.OwnerType, maxPromptOwnerLen)
+			ownerID := sanitizePromptValue(item.OwnerID, maxPromptOwnerLen)
+			lines = append(lines, fmt.Sprintf("  owner: type=%q id=%q", ownerType, ownerID))
+		}
+	}
+
+	return []promptSection{
+		{
+			Title:   "Todo State",
+			Content: strings.Join(lines, "\n"),
+		},
+	}, nil
+}
+
+// sanitizePromptValue 对 Todo 文本字段做去控制字符、折叠空白与长度截断，降低提示注入风险。
+func sanitizePromptValue(value string, maxLen int) string {
+	value = strings.TrimSpace(value)
+	if value == "" || maxLen <= 0 {
+		return ""
+	}
+	parts := strings.Fields(strings.Map(func(r rune) rune {
+		if r < 32 || r == 127 {
+			return ' '
+		}
+		return r
+	}, value))
+	normalized := strings.Join(parts, " ")
+	runes := []rune(normalized)
+	if len(runes) <= maxLen {
+		return normalized
+	}
+	return string(runes[:maxLen])
+}
+
+// sanitizePromptList 对文本列表做逐项规范化、去重和数量限制，避免单条 Todo 扩大注入面。
+func sanitizePromptList(values []string, maxItems int, itemMaxLen int) []string {
+	if len(values) == 0 || maxItems <= 0 || itemMaxLen <= 0 {
+		return nil
+	}
+	result := make([]string, 0, len(values))
+	seen := make(map[string]struct{}, len(values))
+	for _, raw := range values {
+		value := sanitizePromptValue(raw, itemMaxLen)
+		if value == "" {
+			continue
+		}
+		if _, exists := seen[value]; exists {
+			continue
+		}
+		seen[value] = struct{}{}
+		result = append(result, value)
+		if len(result) >= maxItems {
+			break
+		}
+	}
+	if len(result) == 0 {
+		return nil
+	}
+	return result
+}
+
+// todoStatusRank 计算 Todo 状态排序优先级，值越小优先级越高。
+func todoStatusRank(status agentsession.TodoStatus) int {
+	switch status {
+	case agentsession.TodoStatusInProgress:
+		return 0
+	case agentsession.TodoStatusBlocked:
+		return 1
+	case agentsession.TodoStatusPending:
+		return 2
+	default:
+		return 3
+	}
+}