Add review driver, handoff primitive, and group-chat driver (Q2 WP3)

Why: Q2 acceptance 2 requires the squad review topology to be equivalent to
today's backend runReview flow (parallel finders, per-finding verification,
drop unverified); handoff and group_chat complete 11 of 12 builtin topologies.

Evidence: wp3_conformance_test.go mirrors backend review_test.go assertions
(true finder concurrency via release gate, verify calls = 5 unique after
dedupe, only PASS kept, dropped-count line, severity order); handoff records
ownership transfer, target receives filtered history, finalize takes
chain-tail output, unknown target role fails closed; group-chat rotate /
close-marker / moderator conformance with budget stop and fail-closed
unknown nominee. Full suite green with -race.

Impact: review/group_chat drivers lit in the topology registry (task_board
remains fail-closed until WP4); RunState gains Handoffs (persisted);
RunOptions gains GroupChat*/Review* knobs; runOneStep validates handoff
targets and injects handoff context; finalize prefers chain-tail deliverable.
Parse/dedupe/verdict/severity/report formats ported verbatim from backend
internal/runtime/review.go for byte-level report equivalence.

Refs: Q2 plan WP3 (2026-10-07-agent-stack-q2q3-plans.md); task card
.task/feature-agent-stack-q2.md

squad/engine.go

@@ -114,6 +114,16 @@ type RunOptions struct {
 	// MaxReplans leader 模式的重规划上限（Q2；与 MaxLeaderTurns 独立）。
 	// 0 = 默认 DefaultMaxReplans。
 	MaxReplans int `json:"max_replans,omitempty"`
+	// GroupChatPolicy group_chat 拓扑发言人策略（Q2）：rotate（默认）| moderator。
+	GroupChatPolicy string `json:"group_chat_policy,omitempty"`
+	// GroupChatModerator 主持人角色 key（moderator 策略必填，须在名册内）。
+	GroupChatModerator string `json:"group_chat_moderator,omitempty"`
+	// GroupChatMaxTurns 群聊轮次预算（0 = DefaultMaxGroupChatTurns）。
+	GroupChatMaxTurns int `json:"group_chat_max_turns,omitempty"`
+	// ReviewVerifyRole review 拓扑核实角色 key（默认 "verifier"）。
+	ReviewVerifyRole string `json:"review_verify_role,omitempty"`
+	// ReviewTarget 被评审材料（默认取 context/goal.md）。
+	ReviewTarget string `json:"review_target,omitempty"`
 }
 
 // SquadEngine 小队引擎门面：Run / Respond / Resume / Inspect / ListRuns。
@@ -258,6 +268,21 @@ func (e *SquadEngine) Run(ctx context.Context, goal Goal, runOpts RunOptions) (*
 	if runOpts.MaxReplans > 0 {
 		meta.Metadata["max_replans"] = fmt.Sprintf("%d", runOpts.MaxReplans)
 	}
+	if runOpts.GroupChatPolicy != "" {
+		meta.Metadata["group_chat_policy"] = runOpts.GroupChatPolicy
+	}
+	if runOpts.GroupChatModerator != "" {
+		meta.Metadata["group_chat_moderator"] = runOpts.GroupChatModerator
+	}
+	if runOpts.GroupChatMaxTurns > 0 {
+		meta.Metadata["group_chat_max_turns"] = fmt.Sprintf("%d", runOpts.GroupChatMaxTurns)
+	}
+	if runOpts.ReviewVerifyRole != "" {
+		meta.Metadata["review_verify_role"] = runOpts.ReviewVerifyRole
+	}
+	if runOpts.ReviewTarget != "" {
+		meta.Metadata["review_target"] = runOpts.ReviewTarget
+	}
 	e.deps.Sink.Emit(Event{Type: EvRunStarted, RunID: runID, Text: goal.Text, At: time.Now()})
 
 	// 意图闸门（可选，入口一次裁决；显式 TaskKey 优先，不重复过闸）。
@@ -434,6 +459,15 @@ func (e *SquadEngine) planAndExecute(ctx context.Context, st *RunState, runOpts
 		}
 		return out, nil
 	}
+	// driver 类拓扑（Q2 WP3+）：按名分发专用驱动（review/group_chat；
+	// task_board 属 WP4，未点亮前 checkTopology 已 fail-closed）。
+	if out, handled, derr := e.dispatchTopologyDriver(ctx, st); handled {
+		if derr != nil {
+			return nil, derr
+		}
+		e.finalizeEvent(out)
+		return out, nil
+	}
 	out, _, err := drv.advance(ctx, st)
 	if err != nil {
 		return nil, err
@@ -494,6 +528,15 @@ func (e *SquadEngine) resumeAfterHold(ctx context.Context, st *RunState) (*RunRe
 		}
 		return out, nil
 	}
+	// driver 类拓扑续跑：驱动自身幂等（review 已完成 finder 不重跑；
+	// group_chat 按已落盘轮次续转）。
+	if out, handled, err := e.dispatchTopologyDriver(ctx, st); handled {
+		if err != nil {
+			return nil, err
+		}
+		e.finalizeEvent(out)
+		return out, nil
+	}
 	drv := &flowDriver{opts: e.deps}
 	out, _, err := drv.advance(ctx, st)
 	if err != nil {
@@ -503,6 +546,29 @@ func (e *SquadEngine) resumeAfterHold(ctx context.Context, st *RunState) (*RunRe
 	return out, nil
 }
 
+// dispatchTopologyDriver 按运行拓扑分发 driver 类拓扑。
+// handled=false 表示非 driver 拓扑（走既有图/模式路径）。
+func (e *SquadEngine) dispatchTopologyDriver(ctx context.Context, st *RunState) (*RunResult, bool, error) {
+	topo := st.Meta.Metadata["topology"]
+	if topo == "" {
+		return nil, false, nil
+	}
+	spec, ok := LookupTopology(topo)
+	if !ok || spec.Kind != TopologyDriver {
+		return nil, false, nil
+	}
+	switch topo {
+	case TopologyReview:
+		out, err := e.runReviewDriver(ctx, st)
+		return out, true, err
+	case TopologyGroupChat:
+		out, err := e.runGroupChatDriver(ctx, st)
+		return out, true, err
+	default:
+		return e.driverFail(st, fmt.Sprintf("topology: %q 驱动未实现（fail-closed）", topo)), true, nil
+	}
+}
+
 // materializeWorkspace 落盘工作区与子工作区（已存在则只更新计划并重建待执行子目录）。
 func (e *SquadEngine) materializeWorkspace(meta *RunMetadata, st *RunState, plan *SquadPlan) error {
 	if st.Meta.WorkDir == "" {

squad/groupchat.go

@@ -0,0 +1,355 @@
+package squad
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+// groupchat.go — group_chat 拓扑驱动（Q2 WP3）。
+// 形态（计划 §三 WP3 与边界 §五）：共享转录（BB 字段 transcript +
+// group_chat/transcript.md 全量落盘）；发言人策略只做**轮转**与**主持人**
+// 两种（脚本可判定，LLM 选人策略不进库）；预算停机（max_turns，缺省 8）。
+// 蓝图步骤 = 参与者名册（按序，不直接执行，driver 标记 skipped 并派生轮次
+// 步骤）；任一发言含 [close] 标记即收口；主持人模式下主持人输出 JSON 决策
+// （{"next":"role"} / {"action":"close"}），未知角色/非法 JSON fail-closed。
+// 驱动幂等可恢复：轮次由已落盘的 gc 步骤数重建，挂起（权限/HITL）后
+// Respond 重入续转。
+
+func init() {
+	_ = RegisterTopologyDriver(TopologyGroupChat)
+}
+
+// DefaultMaxGroupChatTurns 群聊轮次预算缺省值（预算停机）。
+const DefaultMaxGroupChatTurns = 8
+
+// gcRosterSkipReason 名册步骤的 skipped 原因（非执行步骤，不算降级）。
+const gcRosterSkipReason = "group_chat: 名册步骤（参与者由驱动接管）"
+
+// gcCloseMarker 任一发言包含该标记（大小写不敏感）即收口。
+const gcCloseMarker = "[close]"
+
+// gcTranscriptCapBB 是 BB 转录字段的容量上限（TASK.md 快照只带近端）。
+const gcTranscriptCapBB = 4000
+
+// runGroupChatDriver group_chat 拓扑入口。
+func (e *SquadEngine) runGroupChatDriver(ctx context.Context, st *RunState) (*RunResult, error) {
+	drv := &flowDriver{opts: e.deps}
+
+	// 名册：首次进入从蓝图步骤取参与者序列并持久化到元数据（恢复时直读）。
+	roster, err := e.gcRoster(st)
+	if err != nil {
+		return e.driverFail(st, err.Error()), nil
+	}
+	policy := orDefault(st.Meta.Metadata["group_chat_policy"], "rotate")
+	moderator := st.Meta.Metadata["group_chat_moderator"]
+	if policy != "rotate" && policy != "moderator" {
+		return e.driverFail(st, fmt.Sprintf("group_chat: 未知发言人策略 %q（只支持 rotate/moderator）", policy)), nil
+	}
+	if policy == "moderator" {
+		if moderator == "" || !containsString(roster, moderator) {
+			return e.driverFail(st, fmt.Sprintf("group_chat: 主持人 %q 不在名册内（fail-closed）", moderator)), nil
+		}
+	}
+	maxTurns := DefaultMaxGroupChatTurns
+	if v := st.Meta.Metadata["group_chat_max_turns"]; v != "" {
+		if n := parseIntDefault(v, DefaultMaxGroupChatTurns); n > 0 {
+			maxTurns = n
+		}
+	}
+
+	// 名册步骤标记 skipped（首次进入时；恢复重入无 pending 名册步骤）。
+	st.mu.Lock()
+	for i := range st.Plan.Workflow.Steps {
+		s := &st.Plan.Workflow.Steps[i]
+		if !strings.HasPrefix(s.ID, "gc") && (s.Status == "pending" || s.Status == "running") {
+			s.Status = "skipped"
+			s.Error = gcRosterSkipReason
+		}
+	}
+	_ = st.save()
+	st.mu.Unlock()
+
+	for {
+		// 恢复重入：上次挂起留下的未完 gc 轮次步骤优先续跑（不重新选人）。
+		if idx := e.gcHeldStepIdx(st); idx >= 0 {
+			out, gate, err := e.gcRunStep(ctx, drv, st, idx)
+			if err != nil {
+				return nil, err
+			}
+			if gate != nil {
+				if out == nil {
+					out = heldResult(st, gate)
+				}
+				return out, nil
+			}
+			if out != nil {
+				return out, nil
+			}
+			if e.gcMessageClosed(st, idx) {
+				drv.emit(st, Event{Type: EvPhase, Text: fmt.Sprintf("group_chat：%s 发出收口标记，停机", st.Plan.Workflow.Steps[idx].Role)})
+				break
+			}
+			continue
+		}
+		turns := e.gcTurnCount(st)
+		if turns >= maxTurns {
+			drv.emit(st, Event{Type: EvPhase, Text: fmt.Sprintf("group_chat：轮次预算 %d 用尽，停机收口", maxTurns)})
+			break
+		}
+		speaker, closed, derr := e.gcNextSpeaker(st, roster, policy, moderator, turns)
+		if derr != nil {
+			return e.driverFail(st, derr.Error()), nil
+		}
+		if closed {
+			drv.emit(st, Event{Type: EvPhase, Text: "group_chat：主持人收口"})
+			break
+		}
+		out, gate, err := e.gcRunTurn(ctx, drv, st, turns, speaker)
+		if err != nil {
+			return nil, err
+		}
+		if gate != nil {
+			if out == nil {
+				out = heldResult(st, gate)
+			}
+			return out, nil
+		}
+		if out != nil { // 轮次步骤失败（关键）→ fail-closed 传播
+			return out, nil
+		}
+		if e.gcMessageClosed(st, len(st.Plan.Workflow.Steps)-1) {
+			drv.emit(st, Event{Type: EvPhase, Text: fmt.Sprintf("group_chat：%s 发出收口标记，停机", speaker)})
+			break
+		}
+	}
+	return e.gcFinish(st, drv), nil
+}
+
+// gcRoster 参与者名册（首次从蓝图步骤派生并写入元数据；恢复直读）。
+func (e *SquadEngine) gcRoster(st *RunState) ([]string, error) {
+	if v := st.Meta.Metadata["group_chat_roster"]; v != "" {
+		return strings.Split(v, ","), nil
+	}
+	var roster []string
+	for _, s := range st.Plan.Workflow.Steps {
+		if s.Role != "" && !containsString(roster, s.Role) {
+			roster = append(roster, s.Role)
+		}
+	}
+	if len(roster) == 0 {
+		return nil, fmt.Errorf("group_chat: 名册为空（蓝图步骤即参与者）")
+	}
+	st.mu.Lock()
+	if st.Meta.Metadata == nil {
+		st.Meta.Metadata = map[string]string{}
+	}
+	st.Meta.Metadata["group_chat_roster"] = strings.Join(roster, ",")
+	_ = st.save()
+	st.mu.Unlock()
+	return roster, nil
+}
+
+// gcTurnCount 已完成的轮次数（预算与轮转序号的基准；恢复重入自然续算）。
+func (e *SquadEngine) gcTurnCount(st *RunState) int {
+	n := 0
+	for _, s := range st.Plan.Workflow.Steps {
+		if strings.HasPrefix(s.ID, "gc") && s.Status == "completed" {
+			n++
+		}
+	}
+	return n
+}
+
+// gcHeldStepIdx 返回上次挂起留下的未完 gc 轮次步骤下标（无则 -1）。
+func (e *SquadEngine) gcHeldStepIdx(st *RunState) int {
+	for i := range st.Plan.Workflow.Steps {
+		s := &st.Plan.Workflow.Steps[i]
+		if strings.HasPrefix(s.ID, "gc") && (s.Status == "pending" || s.Status == "running") {
+			return i
+		}
+	}
+	return -1
+}
+
+// gcNextSpeaker 决定下一发言人。rotate = 轮转；moderator = 主持人裁决
+// （上一步是参与者发言 → 主持人接手；主持人决策 close → 收口，next → 指名，
+// 非法 JSON / 未知角色 fail-closed）。
+func (e *SquadEngine) gcNextSpeaker(st *RunState, roster []string, policy, moderator string, turns int) (string, bool, error) {
+	if policy == "rotate" {
+		return roster[turns%len(roster)], false, nil
+	}
+	last := e.gcLastStep(st)
+	if last == nil || last.Role == moderator {
+		// 首轮或上一步就是主持人（不该连续，防御性让主持人接手）。
+		if last != nil && last.Role == moderator {
+			// 解析主持人决策。
+			dec, err := e.gcParseDecision(st, last)
+			if err != nil {
+				return "", false, err
+			}
+			if dec.Action == "close" {
+				return "", true, nil
+			}
+			if !containsString(roster, dec.Next) {
+				return "", false, fmt.Errorf("group_chat: 主持人指名 %q 不在名册内（fail-closed）", dec.Next)
+			}
+			return dec.Next, false, nil
+		}
+		return moderator, false, nil
+	}
+	// 上一步是参与者发言 → 主持人接手裁决。
+	return moderator, false, nil
+}
+
+type gcDecision struct {
+	Action string `json:"action"`
+	Next   string `json:"next"`
+}
+
+// gcParseDecision 宽松解析主持人 message.md 里的 JSON 决策（首 `{` 末 `}`）。
+func (e *SquadEngine) gcParseDecision(st *RunState, step *StepSpec) (*gcDecision, error) {
+	msg := e.gcMessageOf(st, step)
+	start := strings.Index(msg, "{")
+	end := strings.LastIndex(msg, "}")
+	if start < 0 || end <= start {
+		return nil, fmt.Errorf("group_chat: 主持人输出无 JSON 决策（fail-closed）：%q", truncateStr(msg, 80))
+	}
+	var dec gcDecision
+	if err := json.Unmarshal([]byte(msg[start:end+1]), &dec); err != nil {
+		return nil, fmt.Errorf("group_chat: 主持人决策解析失败（fail-closed）: %v", err)
+	}
+	if dec.Action == "close" {
+		return &dec, nil
+	}
+	if strings.TrimSpace(dec.Next) == "" {
+		return nil, fmt.Errorf("group_chat: 主持人决策缺 next/action（fail-closed）")
+	}
+	return &dec, nil
+}
+
+// gcRunTurn 派生一轮发言步骤并执行。
+func (e *SquadEngine) gcRunTurn(ctx context.Context, drv *flowDriver, st *RunState, turns int, speaker string) (*RunResult, *HitlGate, error) {
+	step := StepSpec{
+		ID:           fmt.Sprintf("gc%02d", turns+1),
+		Role:         speaker,
+		Title:        fmt.Sprintf("群聊第 %d 轮：%s 发言（把发言写入 message.md；同意收口就写 [close]）", turns+1, speaker),
+		Targets:      []string{"message.md"},
+		SubWorkspace: fmt.Sprintf("group_chat/turn_%02d_%s", turns+1, speaker),
+		Status:       "pending",
+	}
+	st.mu.Lock()
+	st.Plan.Workflow.Steps = append(st.Plan.Workflow.Steps, step)
+	idx := len(st.Plan.Workflow.Steps) - 1
+	_ = st.save()
+	st.mu.Unlock()
+	return e.gcRunStep(ctx, drv, st, idx)
+}
+
+// gcRunStep 执行一个轮次步骤：过门 → runOneStep → 转录并入共享状态。
+// 挂起（gate）时步骤保持未完，恢复重入经 gcHeldStepIdx 续跑同一步骤。
+func (e *SquadEngine) gcRunStep(ctx context.Context, drv *flowDriver, st *RunState, idx int) (*RunResult, *HitlGate, error) {
+	out, gate, err := drv.gateBeforeRun(ctx, st, idx)
+	if err != nil || gate != nil || out != nil {
+		return out, gate, err
+	}
+	step := st.Plan.Workflow.Steps[idx]
+	drv.emit(st, Event{Type: EvPhase, StepID: step.ID, Role: step.Role,
+		Text: fmt.Sprintf("group_chat：%s 发言（第 %d 轮）", step.Role, e.gcTurnCount(st)+1)})
+	out, gate, err = drv.runOneStep(ctx, st, idx)
+	if err != nil || gate != nil || out != nil {
+		return out, gate, err
+	}
+	// 转录并入共享状态：全量落盘 transcript.md，近端进 BB 字段（下一位
+	// 发言人的 TASK.md 黑板快照可见）。
+	msg := e.gcMessageOf(st, &st.Plan.Workflow.Steps[idx])
+	e.gcAppendTranscript(st, e.gcTurnCount(st), step.Role, msg)
+	return nil, nil, nil
+}
+
+// gcAppendTranscript 追加转录（全量文件 + BB 近端快照）。
+func (e *SquadEngine) gcAppendTranscript(st *RunState, turn int, speaker, msg string) {
+	dir := filepath.Join(st.Meta.WorkDir, "group_chat")
+	_ = os.MkdirAll(dir, 0o755)
+	line := fmt.Sprintf("%d. %s：%s\n", turn, speaker, strings.TrimSpace(msg))
+	f, _ := os.OpenFile(filepath.Join(dir, "transcript.md"), os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
+	if f != nil {
+		_, _ = f.WriteString(line)
+		_ = f.Close()
+	}
+	st.mu.Lock()
+	if st.BB.Fields == nil {
+		st.BB.Fields = map[string]string{}
+	}
+	cur := st.BB.Fields["transcript"] + line
+	if len(cur) > gcTranscriptCapBB {
+		cur = cur[len(cur)-gcTranscriptCapBB:]
+	}
+	st.BB.Fields["transcript"] = cur
+	_ = st.save()
+	st.mu.Unlock()
+}
+
+// gcLastStep 最后一个已完成的派生轮次步骤（主持人决策解析的锚点）。
+func (e *SquadEngine) gcLastStep(st *RunState) *StepSpec {
+	for i := len(st.Plan.Workflow.Steps) - 1; i >= 0; i-- {
+		s := &st.Plan.Workflow.Steps[i]
+		if strings.HasPrefix(s.ID, "gc") && s.Status == "completed" {
+			return s
+		}
+	}
+	return nil
+}
+
+// gcMessageOf 读取某轮的 message.md（缺文件 = 空串）。
+func (e *SquadEngine) gcMessageOf(st *RunState, step *StepSpec) string {
+	data, err := os.ReadFile(filepath.Join(st.Meta.WorkDir, filepath.FromSlash(step.SubWorkspace), "message.md"))
+	if err != nil {
+		return ""
+	}
+	return string(data)
+}
+
+// gcMessageClosed 第 idx 步的发言是否带收口标记。
+func (e *SquadEngine) gcMessageClosed(st *RunState, idx int) bool {
+	if idx < 0 || idx >= len(st.Plan.Workflow.Steps) {
+		return false
+	}
+	msg := e.gcMessageOf(st, &st.Plan.Workflow.Steps[idx])
+	return strings.Contains(strings.ToLower(msg), gcCloseMarker)
+}
+
+// gcFinish 收口：交付物 = 全量转录；写 output.md；状态落盘；构造结果。
+func (e *SquadEngine) gcFinish(st *RunState, drv *flowDriver) *RunResult {
+	transcript := ""
+	if data, err := os.ReadFile(filepath.Join(st.Meta.WorkDir, "group_chat", "transcript.md")); err == nil {
+		transcript = string(data)
+	}
+	report := "# 群聊转录\n\n" + transcript
+	_ = os.WriteFile(filepath.Join(st.Meta.WorkDir, "output.md"), []byte(report), 0o644)
+	turns := e.gcTurnCount(st)
+	st.mu.Lock()
+	wf := st.Workflow()
+	wf.Status = string(RunCompleted)
+	st.setWorkflow(wf)
+	st.Meta.Status = string(RunCompleted)
+	now := time.Now()
+	st.Meta.CompletedAt = &now
+	_ = st.save()
+	st.mu.Unlock()
+	summary := fmt.Sprintf("group_chat：%d 轮发言，转录已收口", turns)
+	drv.emit(st, Event{Type: EvPhase, Text: summary})
+	return &RunResult{RunID: st.Meta.ID, Status: RunCompleted, Plan: planPtr(st),
+		Deliverable: "output.md", Summary: summary, WorkDir: st.Meta.WorkDir}
+}
+
+func truncateStr(s string, n int) string {
+	if len(s) <= n {
+		return s
+	}
+	return s[:n] + "…"
+}

squad/handoff.go

@@ -0,0 +1,91 @@
+package squad
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+// handoff.go — handoff 跨拓扑原语（Q2 WP3）。
+// 语义（计划 §三 WP3）：StepSpec.Handoff 非空的步骤完成后，最终答案所有权
+// 移交给目标角色——① 记录所有权转移（Handoffs，随 RunState 持久化）；
+// ② 目标角色的下一个步骤收到「过滤历史」：只带移交步骤的主产出，不带全量
+// 转录（一次性并入任务书，与 mailbox 同款机制）；③ finalize 汇总交付物时
+// 取链尾（最后一次移交的目标角色）的最后一个完成步骤产出，而非全图最后
+// 完成步骤。目标角色不在小队内 = fail-closed（步骤启动前拒绝）。
+
+// HandoffRecord 是一次所有权转移记录。
+type HandoffRecord struct {
+	FromRole  string    `json:"from_role"`
+	FromStep  string    `json:"from_step"`
+	ToRole    string    `json:"to_role"`
+	Output    string    `json:"output,omitempty"` // 移交步骤主产出（截断上限内）
+	At        time.Time `json:"at"`
+	Delivered bool      `json:"delivered,omitempty"`
+}
+
+// handoffOutputCap 移交上下文的产出截断上限（过滤历史：只带主产出，且限量）。
+const handoffOutputCap = 64 * 1024
+
+// takeHandoffFor 取出移交给某角色的未投递记录，标记已投递（一次性）。
+// 调用方负责随后 st.save()（或在临界区内）。
+func takeHandoffFor(st *RunState, role string) *HandoffRecord {
+	for i := range st.Handoffs {
+		h := &st.Handoffs[i]
+		if h.Delivered || h.ToRole != role {
+			continue
+		}
+		h.Delivered = true
+		out := *h
+		return &out
+	}
+	return nil
+}
+
+// formatHandoffSection 渲染任务书里的移交上下文段（无则空串）。
+func formatHandoffSection(h *HandoffRecord) string {
+	if h == nil {
+		return ""
+	}
+	body := h.Output
+	if len(body) > handoffOutputCap {
+		body = body[:handoffOutputCap] + "\n…（已截断）"
+	}
+	var b strings.Builder
+	fmt.Fprintf(&b, "\n\n## 移交上下文（所有权来自 %s，步骤 %s）\n", h.FromRole, h.FromStep)
+	b.WriteString("以下是移交方的主产出（过滤历史：只含该产出，不含其过程转录）：\n\n")
+	b.WriteString(body)
+	b.WriteString("\n")
+	return b.String()
+}
+
+// handoffChainTail 返回移交链尾角色（无移交记录返回空串）。
+func handoffChainTail(st *RunState) string {
+	if n := len(st.Handoffs); n > 0 {
+		return st.Handoffs[n-1].ToRole
+	}
+	return ""
+}
+
+// recordHandoff 步骤完成时的所有权转移记录：主产出快照（截断上限内）+
+// 持久化 + 事件。目标角色合法性已在步骤启动前 fail-closed 校验。
+func (d *flowDriver) recordHandoff(st *RunState, step StepSpec, subDir string, targets []string) {
+	output := ""
+	if data, err := os.ReadFile(filepath.Join(subDir, firstTarget(targets))); err == nil {
+		output = string(data)
+	}
+	if len(output) > handoffOutputCap {
+		output = output[:handoffOutputCap] + "\n…（已截断）"
+	}
+	st.mu.Lock()
+	st.Handoffs = append(st.Handoffs, HandoffRecord{
+		FromRole: step.Role, FromStep: step.ID, ToRole: step.Handoff,
+		Output: output, At: time.Now(),
+	})
+	_ = st.save()
+	st.mu.Unlock()
+	d.emit(st, Event{Type: EvPhase, StepID: step.ID, Role: step.Role,
+		Text: fmt.Sprintf("handoff：%s → %s（最终答案所有权移交）", step.Role, step.Handoff)})
+}

squad/review.go

@@ -0,0 +1,366 @@
+package squad
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+)
+
+// review.go — review 拓扑驱动（Q2 WP3，验收二）。
+// 与 backend internal/runtime/review.go 的 runReview 等价：
+// 并行 N finder（semaphore 3）→ 宽松 JSON 解析（首 `[` 末 `]`，丢空 issue）
+// → 按 (location,issue) 去重、上限 10 → 每条独立 verifier（尾行
+// VERDICT: PASS/FAIL/PARTIAL）→ 只留 PASS（fail-closed）→ severity 稳定排序
+// → 报告恒带「已丢弃 N 条未验证」。解析/去重/判定/排序/文案与 backend 同一
+// 格式串（计划 §一.5：以报告字节形态为等价判据）。
+//
+// squad 侧接线：finder = 计划步骤（各自的 findings.json 为目标产物，经
+// runOneStep 走完整工作区/事件/HITL 机制）；verifier = 驱动内按 verify 角色
+// 直接 Execute 的核实调用（对应 backend 的 spawn(verifyProfileID,…)），
+// 每次核实落盘 reviews/verify_NN/ 留痕。
+
+func init() {
+	_ = RegisterTopologyDriver(TopologyReview)
+}
+
+// reviewFinding 与 backend reviewFinding 同构（JSON 键一致）。
+type reviewFinding struct {
+	Location string `json:"location"`
+	Severity string `json:"severity"`
+	Issue    string `json:"issue"`
+	Evidence string `json:"evidence"`
+}
+
+// reviewVerbatimTask 是核实调用的任务文案（与 backend runReview 同串）。
+const reviewVerbatimTask = "独立核实这条问题是否成立。材料如下：\n%s\n\n问题：%s\n只在结尾给出一行 VERDICT: PASS、FAIL 或 PARTIAL。"
+
+// parseFindings 宽松解析：首 `[` 末 `]`，丢空 issue（backend 同款）。
+func parseFindings(text string) []reviewFinding {
+	start := strings.Index(text, "[")
+	end := strings.LastIndex(text, "]")
+	if start < 0 || end <= start {
+		return nil
+	}
+	var out []reviewFinding
+	if err := json.Unmarshal([]byte(text[start:end+1]), &out); err != nil {
+		return nil
+	}
+	var kept []reviewFinding
+	for _, f := range out {
+		if strings.TrimSpace(f.Issue) == "" {
+			continue
+		}
+		kept = append(kept, f)
+	}
+	return kept
+}
+
+// dedupeFindings 按 (location,issue) 去重，上限 limit（backend 同款）。
+func dedupeFindings(groups [][]reviewFinding, limit int) []reviewFinding {
+	seen := map[string]bool{}
+	var out []reviewFinding
+	for _, group := range groups {
+		for _, f := range group {
+			key := strings.TrimSpace(f.Location) + "\n" + strings.TrimSpace(f.Issue)
+			if seen[key] {
+				continue
+			}
+			seen[key] = true
+			out = append(out, f)
+			if len(out) >= limit {
+				return out
+			}
+		}
+	}
+	return out
+}
+
+// reviewVerdict 尾行 VERDICT 判定（backend 同款：PASS/FAIL/PARTIAL，
+// 解析不出 = 空串 = 不通过）。
+func reviewVerdict(text string) string {
+	lines := strings.Split(text, "\n")
+	for i := len(lines) - 1; i >= 0; i-- {
+		line := strings.TrimSpace(lines[i])
+		if line == "" || !strings.HasPrefix(strings.ToUpper(line), "VERDICT:") {
+			continue
+		}
+		v := strings.TrimSpace(line[len("VERDICT:"):])
+		v = strings.ToUpper(v)
+		switch {
+		case strings.HasPrefix(v, "PASS"):
+			return "PASS"
+		case strings.HasPrefix(v, "FAIL"):
+			return "FAIL"
+		case strings.HasPrefix(v, "PARTIAL"):
+			return "PARTIAL"
+		default:
+			return ""
+		}
+	}
+	return ""
+}
+
+// severityRank 稳定排序键（backend 同款）。
+func severityRank(s string) int {
+	switch strings.ToLower(strings.TrimSpace(s)) {
+	case "critical":
+		return 0
+	case "high":
+		return 1
+	case "medium":
+		return 2
+	case "low":
+		return 3
+	default:
+		return 4
+	}
+}
+
+// reviewParallel semaphore-3 并行（backend parallel 同款）。
+func reviewParallel(n int, fn func(i int)) {
+	if n <= 0 {
+		return
+	}
+	sem := make(chan struct{}, 3)
+	var wg sync.WaitGroup
+	for i := 0; i < n; i++ {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			sem <- struct{}{}
+			defer func() { <-sem }()
+			fn(i)
+		}(i)
+	}
+	wg.Wait()
+}
+
+// runReviewDriver review 拓扑入口。finder 阶段复用计划步骤（可挂起可恢复：
+// 重入时已完成步骤不重跑，findings.json 从各自子工作区读取）。
+func (e *SquadEngine) runReviewDriver(ctx context.Context, st *RunState) (*RunResult, error) {
+	drv := &flowDriver{opts: e.deps}
+	steps := st.Plan.Workflow.Steps
+
+	// verify 角色先行解析（fail-fast：缺角色不浪费 finder 轮次）。
+	verifyRoleName := orDefault(st.Meta.Metadata["review_verify_role"], "verifier")
+	verifyRole, ok := findAgent(st.Plan.Squad.Agents, verifyRoleName)
+	if !ok {
+		if r, exists := e.deps.Registry.Get(verifyRoleName); exists {
+			verifyRole, ok = r, true
+		}
+	}
+	if !ok {
+		return e.driverFail(st, fmt.Sprintf("review: verify 角色 %q 不在小队内（fail-closed）", verifyRoleName)), nil
+	}
+	verifyBackend, _, rerr := e.deps.Backends.Resolve(verifyRole, st.Meta.Backend)
+	if rerr != nil {
+		return e.driverFail(st, "review: verify 后端解析失败: "+rerr.Error()), nil
+	}
+
+	// 1) finder 阶段：先全组过门（任一要挂起则整组不执行，与 advance 并行组
+	// 同款语义），再 semaphore-3 并行执行。
+	var finderIdx []int
+	for i := range steps {
+		if steps[i].Status == "pending" || steps[i].Status == "running" {
+			finderIdx = append(finderIdx, i)
+		}
+	}
+	for _, idx := range finderIdx {
+		out, gate, err := drv.gateBeforeRun(ctx, st, idx)
+		if err != nil {
+			return nil, err
+		}
+		if gate != nil {
+			if out == nil {
+				out = heldResult(st, gate)
+			}
+			return out, nil
+		}
+		if out != nil {
+			return out, nil
+		}
+	}
+	drv.emit(st, Event{Type: EvPhase, Text: fmt.Sprintf("review：%d 个 finder 并行找问题", len(finderIdx))})
+	var holdGate *HitlGate
+	var holdOut *RunResult
+	var fatal *RunResult
+	finderFailed := 0
+	var fmu sync.Mutex
+	reviewParallel(len(finderIdx), func(k int) {
+		idx := finderIdx[k]
+		out, gate, err := drv.runOneStep(ctx, st, idx)
+		fmu.Lock()
+		defer fmu.Unlock()
+		if err != nil {
+			if fatal == nil {
+				fatal = &RunResult{RunID: st.Meta.ID, Status: RunFailed, Plan: planPtr(st),
+					Error: err.Error(), WorkDir: st.Meta.WorkDir}
+			}
+			return
+		}
+		if gate != nil && holdGate == nil {
+			holdGate = gate
+			holdOut = out
+			return
+		}
+		if out != nil && out.Status == RunFailed && fatal == nil {
+			fatal = out // 关键 finder 失败：fail-closed 传播
+			return
+		}
+		if st.Plan.Workflow.Steps[idx].Status == "failed" {
+			finderFailed++ // 非关键 finder 失败：宽容（backend spawn err 同款），收口降级
+		}
+	})
+	if fatal != nil {
+		return fatal, nil
+	}
+	if holdGate != nil {
+		if holdOut == nil {
+			holdOut = heldResult(st, holdGate)
+		}
+		return holdOut, nil
+	}
+
+	// 2) 收集各 finder 的 findings.json（宽松解析；缺文件/坏 JSON = 该 finder
+	// 零发现，与 backend 同款）。
+	steps = st.Plan.Workflow.Steps
+	groups := make([][]reviewFinding, 0, len(steps))
+	for i := range steps {
+		if steps[i].Status != "completed" {
+			continue
+		}
+		subDir := filepath.Join(st.Meta.WorkDir, filepath.FromSlash(steps[i].SubWorkspace))
+		data, err := os.ReadFile(filepath.Join(subDir, "findings.json"))
+		if err != nil {
+			continue
+		}
+		groups = append(groups, parseFindings(string(data)))
+	}
+	unique := dedupeFindings(groups, 10)
+	drv.emit(st, Event{Type: EvPhase, Text: fmt.Sprintf("review：去重后 %d 条，逐条独立核实", len(unique))})
+
+	// 3) 逐条 verify（semaphore-3 并行；fail-closed：核实调用失败/无判定 = 丢弃）。
+	target := reviewTargetMaterial(st)
+	kept := make([]reviewFinding, len(unique))
+	pass := make([]bool, len(unique))
+	reviewParallel(len(unique), func(i int) {
+		f := unique[i]
+		body, _ := json.Marshal(f)
+		task := fmt.Sprintf(reviewVerbatimTask, target, body)
+		vDir := filepath.Join(st.Meta.WorkDir, "reviews", fmt.Sprintf("verify_%02d", i+1))
+		if err := os.MkdirAll(vDir, 0o755); err != nil {
+			return
+		}
+		instructions := ""
+		if e.deps.Workspaces != nil {
+			instructions = e.deps.Workspaces.ResolveInstructions(verifyRole)
+		}
+		res, err := verifyBackend.Execute(ctx, ExecRequest{
+			WorkDir:      vDir,
+			Prompt:       task,
+			Instructions: instructions,
+			Targets:      []string{"verdict.md"},
+			Timeout:      e.deps.StepTimeout,
+			SessionScope: st.Meta.ID + "/verify_" + fmt.Sprintf("%02d", i+1),
+		})
+		if err != nil || res == nil {
+			return
+		}
+		text := string(res.Patches["verdict.md"]) + "\n" + res.Logs
+		if data, rerr2 := os.ReadFile(filepath.Join(vDir, "verdict.md")); rerr2 == nil {
+			text = string(data) + "\n" + text
+		}
+		if reviewVerdict(text) == "PASS" {
+			kept[i] = f
+			pass[i] = true
+		}
+	})
+	var verified []reviewFinding
+	for i, ok := range pass {
+		if ok {
+			verified = append(verified, kept[i])
+		}
+	}
+
+	// 4) severity 稳定排序 + 等价报告（backend 同格式串）。
+	sort.SliceStable(verified, func(i, j int) bool {
+		return severityRank(verified[i].Severity) < severityRank(verified[j].Severity)
+	})
+	dropped := len(unique) - len(verified)
+	var b strings.Builder
+	if len(verified) == 0 {
+		b.WriteString("没有验证通过的问题。\n")
+	}
+	for _, f := range verified {
+		fmt.Fprintf(&b, "- [%s] %s：%s\n  证据：%s\n",
+			orDefault(f.Severity, "medium"), orDefault(f.Location, "未定位"), f.Issue, f.Evidence)
+	}
+	fmt.Fprintf(&b, "已丢弃 %d 条未验证\n", dropped)
+	report := b.String()
+
+	// 5) 收口：报告落盘（reviews/report.md + output.md 交付物约定），
+	// finder 有失败则降级（诚实信号），否则完成。
+	reviewsDir := filepath.Join(st.Meta.WorkDir, "reviews")
+	_ = os.MkdirAll(reviewsDir, 0o755)
+	_ = os.WriteFile(filepath.Join(reviewsDir, "report.md"), []byte(report), 0o644)
+	_ = os.WriteFile(filepath.Join(st.Meta.WorkDir, "output.md"), []byte(report), 0o644)
+	st.mu.Lock()
+	if st.BB.Fields == nil {
+		st.BB.Fields = map[string]string{}
+	}
+	st.BB.Fields["review_verified"] = fmt.Sprintf("%d", len(verified))
+	st.BB.Fields["review_dropped"] = fmt.Sprintf("%d", dropped)
+	wf := st.Workflow()
+	status := RunCompleted
+	if finderFailed > 0 {
+		status = RunDegraded
+	}
+	wf.Status = string(status)
+	st.setWorkflow(wf)
+	st.Meta.Status = string(status)
+	now := time.Now()
+	st.Meta.CompletedAt = &now
+	_ = st.save()
+	st.mu.Unlock()
+	summary := fmt.Sprintf("review：保留 %d 条 / 丢弃 %d 条未验证", len(verified), dropped)
+	if finderFailed > 0 {
+		summary += fmt.Sprintf("（%d 个 finder 失败，降级）", finderFailed)
+	}
+	drv.emit(st, Event{Type: EvPhase, Text: summary})
+	return &RunResult{RunID: st.Meta.ID, Status: status, Plan: planPtr(st),
+		Deliverable: "output.md", Summary: summary, WorkDir: st.Meta.WorkDir}, nil
+}
+
+// reviewTargetMaterial 取被评审材料：元数据 review_target 优先，
+// 其次运行目标（context/goal.md）。
+func reviewTargetMaterial(st *RunState) string {
+	if v := strings.TrimSpace(st.Meta.Metadata["review_target"]); v != "" {
+		return v
+	}
+	if data, err := os.ReadFile(filepath.Join(st.Meta.WorkDir, "context", "goal.md")); err == nil {
+		return string(data)
+	}
+	return ""
+}
+
+// driverFail 驱动级 fail-closed 收口（与 leaderFail 同款语义）。
+func (e *SquadEngine) driverFail(st *RunState, reason string) *RunResult {
+	now := time.Now()
+	st.mu.Lock()
+	st.Meta.Status = string(RunFailed)
+	st.Meta.CompletedAt = &now
+	wf := st.Workflow()
+	wf.Status = "failed"
+	st.setWorkflow(wf)
+	_ = st.save()
+	st.mu.Unlock()
+	(&flowDriver{opts: e.deps}).emit(st, Event{Type: EvPhase, Text: reason})
+	return &RunResult{RunID: st.Meta.ID, Status: RunFailed, Plan: planPtr(st),
+		Error: reason, WorkDir: st.Meta.WorkDir}
+}

squad/runstate.go

@@ -30,6 +30,9 @@ type RunState struct {
 	// Mailbox 运行内点对点消息（Q2）：随 RunState 持久化；只在步骤启动时
 	// 并入任务书，永不触碰 HITL 门。
 	Mailbox []MailMessage `json:"mailbox,omitempty"`
+	// Handoffs 所有权转移记录（Q2 handoff 原语）：随 RunState 持久化；
+	// 目标角色的下一步骤一次性接收移交上下文，finalize 取链尾产出。
+	Handoffs []HandoffRecord `json:"handoffs,omitempty"`
 	// Usage 按角色累计的 token 用量。
 	Usage map[string]*Usage `json:"usage,omitempty"`
 	// Leader leader-delegation 模式的循环状态（workspace 内 leader.json 持久化）。
@@ -96,6 +99,7 @@ func (st *RunState) persist() error {
 		RepairBudgetGranted:   st.RepairBudgetGranted,
 		Clarifications:        st.Clarifications,
 		Mailbox:               st.Mailbox,
+		Handoffs:              st.Handoffs,
 	})
 }
 
@@ -105,6 +109,7 @@ type diskRunState struct {
 	RepairBudgetGranted   int             `json:"repair_budget_granted,omitempty"`
 	Clarifications        []string        `json:"clarifications,omitempty"`
 	Mailbox               []MailMessage   `json:"mailbox,omitempty"`
+	Handoffs              []HandoffRecord `json:"handoffs,omitempty"`
 }
 
 // Workflow 返回计划的编排清单（简洁访问器）。
@@ -160,6 +165,7 @@ func loadRunState(wsDir string) (*RunState, error) {
 		st.RepairBudgetGranted = disk.RepairBudgetGranted
 		st.Clarifications = disk.Clarifications
 		st.Mailbox = disk.Mailbox
+		st.Handoffs = disk.Handoffs
 	} else if !os.IsNotExist(err) {
 		return nil, err
 	}

squad/topology_conformance_test.go

@@ -384,8 +384,7 @@ func TestTopologyValidationFailsClosed(t *testing.T) {
 		{"未注册名", "bogus_topology", "未知拓扑"},
 		{"primitive 单跑", TopologyMailbox, "跨拓扑原语"},
 		{"primitive 单跑 handoff", TopologyHandoff, "跨拓扑原语"},
-		{"driver 未点亮", TopologyReview, "驱动未注册"},
-		{"driver 未点亮 group_chat", TopologyGroupChat, "驱动未注册"},
+		// review/group_chat 驱动已于 WP3 点亮；task_board 属 WP4，仍未点亮。
 		{"driver 未点亮 task_board", TopologyTaskBoard, "驱动未注册"},
 	}
 	for _, tc := range cases {

squad/workflow.go

@@ -279,6 +279,16 @@ func (d *flowDriver) runOneStep(ctx context.Context, st *RunState, idx int) (*Ru
 			return d.failStep(ctx, st, idx)
 		}
 	}
+	// handoff 原语 fail-closed（Q2）：目标角色必须可解析，启动前拒绝。
+	if step.Handoff != "" {
+		if _, ok := findAgent(st.Plan.Squad.Agents, step.Handoff); !ok {
+			if _, exists := d.opts.Registry.Get(step.Handoff); !exists {
+				step.Status, step.Error = "failed", "handoff: 未知目标角色 "+step.Handoff
+				st.setStep(idx, step)
+				return d.failStep(ctx, st, idx)
+			}
+		}
+	}
 	subDir := filepath.Join(st.Meta.WorkDir, filepath.FromSlash(orDefault(step.SubWorkspace, fmt.Sprintf("tasks/%02d_%s", idx+1, step.Role))))
 	if err := os.MkdirAll(subDir, 0o755); err != nil {
 		return nil, nil, err
@@ -313,11 +323,14 @@ func (d *flowDriver) runOneStep(ctx context.Context, st *RunState, idx int) (*Ru
 	// 任务书；只走 prompt 面，永不触碰 HITL 门（验收三构造性保证）。
 	st.mu.Lock()
 	mail := takeMailFor(st, step.Role)
-	if len(mail) > 0 {
+	handoff := takeHandoffFor(st, step.Role)
+	if len(mail) > 0 || handoff != nil {
 		_ = st.save()
 	}
 	st.mu.Unlock()
 	prompt += formatMailSection(mail)
+	// handoff 原语（Q2）：目标角色的步骤接收过滤历史（只带移交方主产出）。
+	prompt += formatHandoffSection(handoff)
 	instructions := readFileOr(filepath.Join(subDir, "AGENTS.md"), d.opts.Workspaces.ResolveInstructions(role))
 
 	var backend Executor
@@ -464,6 +477,12 @@ func (d *flowDriver) runOneStep(ctx context.Context, st *RunState, idx int) (*Ru
 	d.emit(st, Event{Type: EvStepCompleted, StepID: step.ID, Role: step.Role, Text: step.Title,
 		Data: marshalJSON(map[string]any{"duration_ms": step.DurationMs, "targets": targets})})
 
+	// handoff 原语（Q2）：完成即移交最终答案所有权——记录 + 主产出快照，
+	// 供目标角色下一步骤（过滤历史）与 finalize（链尾产出）消费。
+	if step.Handoff != "" {
+		d.recordHandoff(st, step, subDir, targets)
+	}
+
 	// 循环步再武装（Q2 loop）：停机条件不满足且预算未尽 → 本步与 loop.body
 	// 一起重置为 pending；触顶发 loop_exhausted 事件后按完成继续。
 	if step.Loop != nil {
@@ -775,12 +794,21 @@ func (d *flowDriver) finalize(ctx context.Context, st *RunState) (*RunResult, *H
 		}
 	}
 	// 汇总交付物：最后一个 completed 步骤的主产出 → output.md。
+	// handoff 链尾优先（Q2）：有所有权移交时，交付物取链尾角色的最后一个
+	// completed 步骤产出（最终答案所有权在链尾），无则该角色无完成步骤时回落。
 	var srcStep *StepSpec
 	for i := range wf.Steps {
 		if wf.Steps[i].Status == "completed" {
 			srcStep = &wf.Steps[i]
 		}
 	}
+	if tail := handoffChainTail(st); tail != "" {
+		for i := range wf.Steps {
+			if wf.Steps[i].Status == "completed" && wf.Steps[i].Role == tail {
+				srcStep = &wf.Steps[i]
+			}
+		}
+	}
 	if srcStep == nil {
 		wf.Status = "failed"
 		st.setWorkflow(wf)

squad/wp3_conformance_test.go

@@ -0,0 +1,452 @@
+package squad
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+)
+
+// wp3_conformance_test.go — Q2 WP3 验收：review 拓扑与 backend runReview 等价
+// （验收二：并行找问题、逐条验证、丢掉未验证）、handoff 原语（所有权转移 +
+// 过滤历史 + finalize 链尾）、group_chat 驱动（轮转/主持人 + 预算停机）。
+
+// ---- review：与 backend review_test.go 同款断言 ----
+
+// reviewScriptBackend finder 目录回放 findings.json（第 3 个进入者放行，钉住
+// 真并发）；verify_* 目录按 prompt 内容回放判定（与 backend 夹具同文案）。
+type reviewScriptBackend struct {
+	mu          sync.Mutex
+	once        sync.Once
+	entered     int
+	verifyCalls int
+	release     chan struct{}
+}
+
+func (b *reviewScriptBackend) Name() string { return "review-script" }
+
+func (b *reviewScriptBackend) Execute(_ context.Context, req ExecRequest) (*ExecResult, error) {
+	key := filepath.Base(filepath.Clean(req.WorkDir))
+	if strings.HasPrefix(key, "verify_") {
+		b.mu.Lock()
+		b.verifyCalls++
+		b.mu.Unlock()
+		verdict := "看不出对错"
+		switch {
+		case strings.Contains(req.Prompt, "无来源"):
+			verdict = "核对原文确实没有来源。\nVERDICT: PASS"
+		case strings.Contains(req.Prompt, "错字"):
+			verdict = "核对后成立。\nVERDICT: PASS"
+		case strings.Contains(req.Prompt, "过期数据"):
+			verdict = "数据仍有效。\nVERDICT: FAIL"
+		}
+		return writeOne(req.WorkDir, "verdict.md", verdict), nil
+	}
+	// finder：三个必须同时在跑（backend review_test.go:16-33 同款门）。
+	b.mu.Lock()
+	b.entered++
+	n := b.entered
+	b.mu.Unlock()
+	if n == 3 {
+		b.once.Do(func() { close(b.release) })
+	}
+	select {
+	case <-b.release:
+	case <-time.After(time.Second):
+		return nil, fmt.Errorf("finders did not run together")
+	}
+	var findings string
+	switch key {
+	case "01_researcher":
+		findings = `[{"location":"第2段","severity":"high","issue":"无来源","evidence":"显然"},{"location":"第1段","severity":"low","issue":"错字","evidence":"的地"},{"location":"表1","severity":"medium","issue":"过期数据","evidence":"2020"}]`
+	case "02_writer":
+		findings = `[{"location":"第2段","severity":"high","issue":"无来源","evidence":"显然"},{"location":"附录","severity":"medium","issue":"数字不一致","evidence":"3 与 4"}]`
+	default:
+		findings = `[{"location":"结尾","severity":"low","issue":"没有结论","evidence":"最后一句"}]`
+	}
+	return writeOne(req.WorkDir, "findings.json", findings), nil
+}
+
+func writeOne(dir, name, content string) *ExecResult {
+	out := filepath.Join(dir, name)
+	_ = os.MkdirAll(filepath.Dir(out), 0o755)
+	_ = os.WriteFile(out, []byte(content), 0o644)
+	return &ExecResult{Success: true, Patches: map[string][]byte{name: []byte(content)}}
+}
+
+func TestTopologyConformance_review(t *testing.T) {
+	be := &reviewScriptBackend{release: make(chan struct{})}
+	sink := &collectSink{}
+	planner := mockScriptPlanner(
+		StepSpec{ID: "f1", Role: "researcher", Title: "评审一", Targets: []string{"findings.json"}},
+		StepSpec{ID: "f2", Role: "writer", Title: "评审二", Targets: []string{"findings.json"}},
+		StepSpec{ID: "f3", Role: "reviewer", Title: "评审三", Targets: []string{"findings.json"}},
+	)
+	planner.Agents = []RoleSpec{
+		{Role: "researcher", Name: "评审一", Backend: "review-script"},
+		{Role: "writer", Name: "评审二", Backend: "review-script"},
+		{Role: "reviewer", Name: "评审三", Backend: "review-script"},
+		{Role: "verifier", Name: "核实", Backend: "review-script"},
+	}
+	engine := newWP3Engine(t, planner, be, sink, []RoleSpec{
+		{Role: "researcher", Name: "评审一", Backend: "review-script"},
+		{Role: "writer", Name: "评审二", Backend: "review-script"},
+		{Role: "reviewer", Name: "评审三", Backend: "review-script"},
+		{Role: "verifier", Name: "核实", Backend: "review-script"},
+	})
+	res, err := engine.Run(context.Background(), Goal{Text: "评审材料正文"},
+		RunOptions{Topology: TopologyReview, ReviewTarget: "材料正文"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.Status != RunCompleted {
+		t.Fatalf("status = %s err = %v", res.Status, res.Error)
+	}
+	data, err := os.ReadFile(filepath.Join(res.WorkDir, "output.md"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	out := string(data)
+	// 只留 PASS（fail-closed）：无来源/错字保留；FAIL 与无判定丢弃。
+	if !strings.Contains(out, "无来源") || !strings.Contains(out, "错字") ||
+		strings.Contains(out, "数字不一致") || strings.Contains(out, "没有结论") ||
+		strings.Contains(out, "过期数据") {
+		t.Fatalf("filter = %s", out)
+	}
+	// 报告恒带丢弃计数（backend 同格式串）。
+	if !strings.Contains(out, "已丢弃 3 条未验证") {
+		t.Fatalf("dropped = %s", out)
+	}
+	// 去重后逐条验证：verify 调用数 = unique 数 = 5。
+	if be.verifyCalls != 5 {
+		t.Fatalf("verify calls = %d, want 5 after dedupe", be.verifyCalls)
+	}
+	// severity 稳定排序：high(无来源) 在 low(错字) 前。
+	if strings.Index(out, "无来源") > strings.Index(out, "错字") {
+		t.Fatalf("severity order: %s", out)
+	}
+	if sink.countText("review：3 个 finder 并行找问题") != 1 ||
+		sink.countText("review：去重后 5 条") != 1 {
+		t.Fatal("缺 review 阶段事件")
+	}
+}
+
+// verify 角色缺失 → fail-closed。
+func TestReviewVerifyRoleMissingFailsClosed(t *testing.T) {
+	be := &reviewScriptBackend{release: make(chan struct{})}
+	planner := mockScriptPlanner(
+		StepSpec{ID: "f1", Role: "researcher", Title: "评审", Targets: []string{"findings.json"}},
+	)
+	engine := newWP3Engine(t, planner, be, NopSink{}, []RoleSpec{
+		{Role: "researcher", Name: "评审", Backend: "review-script"},
+	})
+	res, err := engine.Run(context.Background(), Goal{Text: "评审"},
+		RunOptions{Topology: TopologyReview})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.Status != RunFailed || !strings.Contains(res.Error, "verify 角色") {
+		t.Fatalf("应 fail-closed：%s %q", res.Status, res.Error)
+	}
+}
+
+// ---- handoff 原语 ----
+
+// handoffScriptBackend 记录 prompt 并按目录回放带标记的产出（≥50 字过最小质检）。
+type handoffScriptBackend struct {
+	mu      sync.Mutex
+	prompts map[string][]string
+}
+
+func (b *handoffScriptBackend) Name() string { return "handoff-script" }
+
+func (b *handoffScriptBackend) Execute(_ context.Context, req ExecRequest) (*ExecResult, error) {
+	key := filepath.Base(filepath.Clean(req.WorkDir))
+	b.mu.Lock()
+	b.prompts[key] = append(b.prompts[key], req.Prompt)
+	b.mu.Unlock()
+	pad := "\n\n这是为了满足最小质检长度要求而补充的正文内容，超过五十个字符。"
+	var content string
+	switch key {
+	case "01_researcher":
+		content = "MARK_RESEARCHER 调研笔记。" + pad
+	case "02_writer":
+		content = "MARK_WRITER 终稿。" + pad
+	default:
+		content = "MARK_REVIEWER 评审意见。" + pad
+	}
+	name := "output.md"
+	if len(req.Targets) > 0 {
+		name = req.Targets[0]
+	}
+	return writeOne(req.WorkDir, name, content), nil
+}
+
+func TestTopologyConformance_handoff(t *testing.T) {
+	be := &handoffScriptBackend{prompts: map[string][]string{}}
+	sink := &collectSink{}
+	engine := newWP3Engine(t, mockScriptPlanner(
+		StepSpec{ID: "s1", Role: "researcher", Title: "调研", Targets: []string{"notes.md"}, Handoff: "writer"},
+		StepSpec{ID: "s2", Role: "writer", Title: "成文", Targets: []string{"output.md"}, Needs: []string{"s1"}},
+		StepSpec{ID: "s3", Role: "reviewer", Title: "终审", Targets: []string{"output.md"}, Needs: []string{"s2"}},
+	), be, sink, []RoleSpec{
+		{Role: "researcher", Name: "调研", Backend: "handoff-script"},
+		{Role: "writer", Name: "撰写", Backend: "handoff-script"},
+		{Role: "reviewer", Name: "审核", Backend: "handoff-script"},
+	})
+	res, err := engine.Run(context.Background(), Goal{Text: "带移交的三步"}, RunOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.Status != RunCompleted {
+		t.Fatalf("status = %s err = %v", res.Status, res.Error)
+	}
+	// ① 所有权转移记录持久化。
+	st, err := engine.loadRun(engine.runDir(res.RunID))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(st.Handoffs) != 1 || st.Handoffs[0].FromRole != "researcher" || st.Handoffs[0].ToRole != "writer" {
+		t.Fatalf("Handoffs = %+v", st.Handoffs)
+	}
+	if !strings.Contains(st.Handoffs[0].Output, "MARK_RESEARCHER") {
+		t.Fatalf("移交产出快照缺失：%q", st.Handoffs[0].Output)
+	}
+	if sink.countText("handoff：researcher → writer") != 1 {
+		t.Fatal("缺所有权移交事件")
+	}
+	// ② 目标收过滤历史：writer 的任务书带移交上下文，reviewer 不带。
+	var writerPrompt, reviewerPrompt string
+	for _, p := range be.prompts["02_writer"] {
+		writerPrompt += p
+	}
+	for _, p := range be.prompts["03_reviewer"] {
+		reviewerPrompt += p
+	}
+	if !strings.Contains(writerPrompt, "移交上下文") || !strings.Contains(writerPrompt, "MARK_RESEARCHER") {
+		t.Fatalf("writer 未收到过滤历史：%q", writerPrompt)
+	}
+	if strings.Contains(reviewerPrompt, "移交上下文") {
+		t.Fatal("非目标角色不应收到移交上下文")
+	}
+	// ③ finalize 取链尾输出：交付物 = writer（链尾）产出，而非最后完成的 reviewer。
+	data, err := os.ReadFile(filepath.Join(res.WorkDir, "output.md"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(string(data), "MARK_WRITER") || strings.Contains(string(data), "MARK_REVIEWER") {
+		t.Fatalf("交付物应为链尾 writer 产出：%s", data)
+	}
+}
+
+// handoff 目标角色未知 → 步骤启动前 fail-closed。
+func TestHandoffUnknownRoleFailsClosed(t *testing.T) {
+	be := &handoffScriptBackend{prompts: map[string][]string{}}
+	engine := newWP3Engine(t, mockScriptPlanner(
+		StepSpec{ID: "s1", Role: "researcher", Title: "调研", Handoff: "ghost"},
+	), be, NopSink{}, []RoleSpec{
+		{Role: "researcher", Name: "调研", Backend: "handoff-script"},
+	})
+	res, err := engine.Run(context.Background(), Goal{Text: "x"}, RunOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.Status != RunFailed || !strings.Contains(res.Error, "handoff: 未知目标角色 ghost") {
+		t.Fatalf("应 fail-closed：%s %q", res.Status, res.Error)
+	}
+}
+
+// ---- group_chat 驱动 ----
+
+// gcScriptBackend 按目录回放 message.md。
+type gcScriptBackend struct {
+	messages map[string]string
+}
+
+func (b *gcScriptBackend) Name() string { return "gc-script" }
+
+func (b *gcScriptBackend) Execute(_ context.Context, req ExecRequest) (*ExecResult, error) {
+	key := filepath.Base(filepath.Clean(req.WorkDir))
+	msg := b.messages[key]
+	if msg == "" {
+		msg = "发言：" + key
+	}
+	return writeOne(req.WorkDir, "message.md", msg), nil
+}
+
+func TestTopologyConformance_groupChatRotateBudget(t *testing.T) {
+	be := &gcScriptBackend{messages: map[string]string{
+		"turn_01_researcher": "第一句",
+		"turn_02_writer":     "第二句",
+		"turn_03_researcher": "第三句",
+	}}
+	sink := &collectSink{}
+	engine := newWP3Engine(t, mockScriptPlanner(
+		StepSpec{ID: "p1", Role: "researcher", Title: "参与者甲"},
+		StepSpec{ID: "p2", Role: "writer", Title: "参与者乙"},
+	), be, sink, []RoleSpec{
+		{Role: "researcher", Name: "甲", Backend: "gc-script"},
+		{Role: "writer", Name: "乙", Backend: "gc-script"},
+	})
+	res, err := engine.Run(context.Background(), Goal{Text: "群聊"},
+		RunOptions{Topology: TopologyGroupChat, GroupChatMaxTurns: 3})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.Status != RunCompleted {
+		t.Fatalf("status = %s err = %v", res.Status, res.Error)
+	}
+	// 预算停机：恰好 3 轮，轮转序 researcher→writer→researcher。
+	if sink.countText("轮次预算 3 用尽") != 1 {
+		t.Fatal("缺预算停机事件")
+	}
+	data, err := os.ReadFile(filepath.Join(res.WorkDir, "output.md"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	out := string(data)
+	for _, want := range []string{"1. researcher：第一句", "2. writer：第二句", "3. researcher：第三句"} {
+		if !strings.Contains(out, want) {
+			t.Fatalf("转录缺 %q：%s", want, out)
+		}
+	}
+	if strings.Contains(out, "4. ") {
+		t.Fatalf("超出预算仍在发言：%s", out)
+	}
+	// 名册步骤不执行，标记 skipped（非降级原因）。
+	st, _ := engine.loadRun(engine.runDir(res.RunID))
+	for _, s := range st.Plan.Workflow.Steps {
+		if s.ID == "p1" || s.ID == "p2" {
+			if s.Status != "skipped" || s.Error != gcRosterSkipReason {
+				t.Fatalf("名册步骤 %s = %s/%q", s.ID, s.Status, s.Error)
+			}
+		}
+	}
+}
+
+func TestTopologyConformance_groupChatCloseMarker(t *testing.T) {
+	be := &gcScriptBackend{messages: map[string]string{
+		"turn_01_researcher": "我先说",
+		"turn_02_writer":     "同意收口 [close]",
+	}}
+	sink := &collectSink{}
+	engine := newWP3Engine(t, mockScriptPlanner(
+		StepSpec{ID: "p1", Role: "researcher", Title: "甲"},
+		StepSpec{ID: "p2", Role: "writer", Title: "乙"},
+	), be, sink, []RoleSpec{
+		{Role: "researcher", Name: "甲", Backend: "gc-script"},
+		{Role: "writer", Name: "乙", Backend: "gc-script"},
+	})
+	res, err := engine.Run(context.Background(), Goal{Text: "群聊"},
+		RunOptions{Topology: TopologyGroupChat, GroupChatMaxTurns: 8})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.Status != RunCompleted {
+		t.Fatalf("status = %s", res.Status)
+	}
+	if sink.countText("发出收口标记") != 1 {
+		t.Fatal("缺收口标记事件")
+	}
+	st, _ := engine.loadRun(engine.runDir(res.RunID))
+	if n := countGcSteps(st); n != 2 {
+		t.Fatalf("收口标记后应停在 2 轮，实际 %d", n)
+	}
+}
+
+func TestTopologyConformance_groupChatModerator(t *testing.T) {
+	be := &gcScriptBackend{messages: map[string]string{
+		"turn_01_researcher": `{"next":"writer","reason":"请乙补充"}`,
+		"turn_02_writer":     "补一段分析",
+		"turn_03_researcher": `{"action":"close","reason":"讨论充分"}`,
+	}}
+	sink := &collectSink{}
+	engine := newWP3Engine(t, mockScriptPlanner(
+		StepSpec{ID: "p1", Role: "researcher", Title: "主持人"},
+		StepSpec{ID: "p2", Role: "writer", Title: "乙"},
+	), be, sink, []RoleSpec{
+		{Role: "researcher", Name: "主持", Backend: "gc-script"},
+		{Role: "writer", Name: "乙", Backend: "gc-script"},
+	})
+	res, err := engine.Run(context.Background(), Goal{Text: "主持人群聊"}, RunOptions{
+		Topology: TopologyGroupChat, GroupChatPolicy: "moderator",
+		GroupChatModerator: "researcher", GroupChatMaxTurns: 8,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.Status != RunCompleted {
+		t.Fatalf("status = %s err = %v", res.Status, res.Error)
+	}
+	if sink.countText("主持人收口") != 1 {
+		t.Fatal("缺主持人收口事件")
+	}
+	data, _ := os.ReadFile(filepath.Join(res.WorkDir, "output.md"))
+	out := string(data)
+	for _, want := range []string{"1. researcher", "2. writer：补一段分析", "3. researcher"} {
+		if !strings.Contains(out, want) {
+			t.Fatalf("转录缺 %q：%s", want, out)
+		}
+	}
+	st, _ := engine.loadRun(engine.runDir(res.RunID))
+	if n := countGcSteps(st); n != 3 {
+		t.Fatalf("主持人模式应 3 轮收口，实际 %d", n)
+	}
+}
+
+// 主持人指名不在名册 → fail-closed。
+func TestGroupChatModeratorUnknownNextFailsClosed(t *testing.T) {
+	be := &gcScriptBackend{messages: map[string]string{
+		"turn_01_researcher": `{"next":"ghost"}`,
+	}}
+	engine := newWP3Engine(t, mockScriptPlanner(
+		StepSpec{ID: "p1", Role: "researcher", Title: "主持人"},
+		StepSpec{ID: "p2", Role: "writer", Title: "乙"},
+	), be, NopSink{}, []RoleSpec{
+		{Role: "researcher", Name: "主持", Backend: "gc-script"},
+		{Role: "writer", Name: "乙", Backend: "gc-script"},
+	})
+	res, err := engine.Run(context.Background(), Goal{Text: "x"}, RunOptions{
+		Topology: TopologyGroupChat, GroupChatPolicy: "moderator", GroupChatModerator: "researcher",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.Status != RunFailed || !strings.Contains(res.Error, "不在名册内") {
+		t.Fatalf("应 fail-closed：%s %q", res.Status, res.Error)
+	}
+}
+
+// ---- 夹具 ----
+
+func countGcSteps(st *RunState) int {
+	n := 0
+	for _, s := range st.Plan.Workflow.Steps {
+		if strings.HasPrefix(s.ID, "gc") && s.Status == "completed" {
+			n++
+		}
+	}
+	return n
+}
+
+func newWP3Engine(t *testing.T, planner Planner, be Executor, sink ProgressSink, roles []RoleSpec) *SquadEngine {
+	t.Helper()
+	dir := t.TempDir()
+	reg := NewRoleRegistry()
+	for _, r := range roles {
+		if err := reg.Register(r); err != nil {
+			t.Fatal(err)
+		}
+	}
+	backends := NewBackendResolver()
+	backends.RegisterInstance(be.Name(), be)
+	engine, err := NewEngine(Options{DataDir: dir, Registry: reg, Planner: planner, Backends: backends, Sink: sink})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return engine
+}