docs: add best exit current display plan

2026-09-30 08:16:37 +08:00 · 2026-05-01 12:24:50 +08:00
parent 950e9a9ba8
commit d98377a297
1 changed files with 892 additions and 0 deletions
@@ -0,0 +1,892 @@
+# Best Exit Current Display Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Show the currently applied `best` exit selection in the tunnel list information, including per-entry/per-final-hop details for multi-owner tunnels.
+
+**Architecture:** Add a backend-only display layer that snapshots `bestExitManager` state and attaches `bestExitState` to existing `tunnelList`/`tunnelGet` responses. Render that state in the existing tunnel table/grid topology area using compact text and a native `title` detail tooltip. No routing, scoring, persistence, polling, or runtime update behavior changes.
+
+**Tech Stack:** Go `net/http` handlers + existing repository methods, React/TypeScript in `vite-frontend/src/pages/tunnel.tsx`, Tailwind/shadcn bridge components already in the file.
+
+---
+
+## File Structure
+
+- Create `go-backend/internal/http/handler/tunnel_best_exit_display.go`: response DTOs, manager snapshot method, tunnel-response parsing helpers, and `Handler.attachBestExitStates`.
+- Create `go-backend/internal/http/handler/tunnel_best_exit_display_test.go`: backend display-state unit tests.
+- Modify `go-backend/internal/http/handler/handler.go`: call `h.attachBestExitStatesOrLog(items)` in `tunnelList`.
+- Modify `go-backend/internal/http/handler/mutations.go`: call `h.attachBestExitStatesOrLog(items)` before returning a single tunnel in `tunnelGet`.
+- Modify `vite-frontend/src/pages/tunnel.tsx`: add `bestExitState` types, map API state, helper render functions, and table/grid display.
+
+---
+
+### Task 1: Backend Snapshot And Display-State Tests
+
+**Files:**
+- Create: `go-backend/internal/http/handler/tunnel_best_exit_display_test.go`
+
+- [ ] **Step 1: Write failing backend display tests**
+
+Create `go-backend/internal/http/handler/tunnel_best_exit_display_test.go`:
+
+```go
+package handler
+
+import (
+	"testing"
+	"time"
+)
+
+func TestBestExitDecisionSnapshotIsDefensiveCopy(t *testing.T) {
+	m := newBestExitManager()
+	key := bestExitOwnerKey{TunnelID: 77, OwnerNodeID: 10}
+	now := time.Unix(100, 0)
+	score := scoreBestExitCandidate(10, chainNodeRecord{NodeID: 30, NodeName: "exit-a"}, 10, 0, 20, 0)
+
+	m.observeScores(key, []bestExitCandidateScore{score}, now)
+	snapshot, ok := m.snapshot(key)
+	if !ok {
+		t.Fatalf("expected snapshot")
+	}
+	if snapshot.AppliedExitNodeID != 30 || snapshot.UpdatedAt != now.UnixMilli() {
+		t.Fatalf("unexpected snapshot: %+v", snapshot)
+	}
+	if len(snapshot.Scores) != 1 {
+		t.Fatalf("expected one score in snapshot, got %+v", snapshot.Scores)
+	}
+	snapshot.Scores[0].ExitNodeID = 99
+
+	again, ok := m.snapshot(key)
+	if !ok {
+		t.Fatalf("expected second snapshot")
+	}
+	if again.Scores[0].ExitNodeID != 30 {
+		t.Fatalf("snapshot score mutation leaked into manager state: %+v", again.Scores)
+	}
+}
+
+func TestBuildBestExitDisplayStateForDirectMultiEntryOwners(t *testing.T) {
+	m := newBestExitManager()
+	now := time.Unix(100, 0)
+	m.setApplied(bestExitOwnerKey{TunnelID: 77, OwnerNodeID: 10}, 30, now)
+	m.setApplied(bestExitOwnerKey{TunnelID: 77, OwnerNodeID: 11}, 31, now.Add(time.Second))
+
+	tunnel := map[string]interface{}{
+		"id": int64(77),
+		"inNodeId": []map[string]interface{}{
+			{"nodeId": int64(10)},
+			{"nodeId": int64(11)},
+		},
+		"outNodeId": []map[string]interface{}{
+			{"nodeId": int64(30), "strategy": tunnelStrategyBest},
+			{"nodeId": int64(31), "strategy": tunnelStrategyBest},
+		},
+		"chainNodes": [][]map[string]interface{}{},
+	}
+	names := map[int64]string{10: "入口 A", 11: "入口 B", 30: "香港节点", 31: "日本节点"}
+
+	state, ok := buildBestExitDisplayState(tunnel, m, testBestExitNameLookup(names))
+	if !ok {
+		t.Fatalf("expected best exit state")
+	}
+	if !state.Enabled || state.Summary != "多个出口" || state.Status != "applied" {
+		t.Fatalf("unexpected state summary: %+v", state)
+	}
+	if state.UpdatedAt != now.Add(time.Second).UnixMilli() {
+		t.Fatalf("expected latest updatedAt, got %d", state.UpdatedAt)
+	}
+	if len(state.Items) != 2 {
+		t.Fatalf("expected two owner items, got %+v", state.Items)
+	}
+	if state.Items[0].OwnerRole != "entry" || state.Items[0].OwnerNodeName != "入口 A" || state.Items[0].ExitNodeName != "香港节点" {
+		t.Fatalf("unexpected first item: %+v", state.Items[0])
+	}
+	if state.Items[1].OwnerRole != "entry" || state.Items[1].OwnerNodeName != "入口 B" || state.Items[1].ExitNodeName != "日本节点" {
+		t.Fatalf("unexpected second item: %+v", state.Items[1])
+	}
+}
+
+func TestBuildBestExitDisplayStateForFinalChainHopOwners(t *testing.T) {
+	m := newBestExitManager()
+	now := time.Unix(200, 0)
+	m.setApplied(bestExitOwnerKey{TunnelID: 88, OwnerNodeID: 20}, 30, now)
+	m.setApplied(bestExitOwnerKey{TunnelID: 88, OwnerNodeID: 21}, 30, now.Add(time.Second))
+
+	tunnel := map[string]interface{}{
+		"id": int64(88),
+		"inNodeId": []map[string]interface{}{
+			{"nodeId": int64(10)},
+		},
+		"outNodeId": []map[string]interface{}{
+			{"nodeId": int64(30), "strategy": tunnelStrategyBest},
+			{"nodeId": int64(31), "strategy": tunnelStrategyBest},
+		},
+		"chainNodes": [][]map[string]interface{}{
+			{{"nodeId": int64(15), "inx": int64(0)}},
+			{{"nodeId": int64(20), "inx": int64(1)}, {"nodeId": int64(21), "inx": int64(1)}},
+		},
+	}
+	names := map[int64]string{20: "中转 M1", 21: "中转 M2", 30: "香港节点", 31: "日本节点"}
+
+	state, ok := buildBestExitDisplayState(tunnel, m, testBestExitNameLookup(names))
+	if !ok {
+		t.Fatalf("expected best exit state")
+	}
+	if state.Summary != "香港节点" || state.Status != "applied" {
+		t.Fatalf("expected single-exit summary, got %+v", state)
+	}
+	if len(state.Items) != 2 {
+		t.Fatalf("expected two final-hop owner items, got %+v", state.Items)
+	}
+	if state.Items[0].OwnerRole != "chain" || state.Items[0].OwnerNodeName != "中转 M1" || state.Items[0].ExitNodeName != "香港节点" {
+		t.Fatalf("unexpected first chain owner item: %+v", state.Items[0])
+	}
+	if state.Items[1].OwnerRole != "chain" || state.Items[1].OwnerNodeName != "中转 M2" || state.Items[1].ExitNodeName != "香港节点" {
+		t.Fatalf("unexpected second chain owner item: %+v", state.Items[1])
+	}
+}
+
+func TestBuildBestExitDisplayStateWaitingWhenNoAppliedDecisionExists(t *testing.T) {
+	tunnel := map[string]interface{}{
+		"id": int64(77),
+		"inNodeId": []map[string]interface{}{
+			{"nodeId": int64(10)},
+		},
+		"outNodeId": []map[string]interface{}{
+			{"nodeId": int64(30), "strategy": tunnelStrategyBest},
+			{"nodeId": int64(31), "strategy": tunnelStrategyBest},
+		},
+		"chainNodes": [][]map[string]interface{}{},
+	}
+	names := map[int64]string{10: "入口 A", 30: "香港节点", 31: "日本节点"}
+
+	state, ok := buildBestExitDisplayState(tunnel, newBestExitManager(), testBestExitNameLookup(names))
+	if !ok {
+		t.Fatalf("expected waiting best exit state")
+	}
+	if state.Summary != "等待探测" || state.Status != "waiting" {
+		t.Fatalf("expected waiting state, got %+v", state)
+	}
+	if len(state.Items) != 1 || state.Items[0].ExitNodeID != 0 || state.Items[0].ExitNodeName != "等待探测" {
+		t.Fatalf("unexpected waiting item: %+v", state.Items)
+	}
+}
+
+func TestBuildBestExitDisplayStateSkipsNonBestAndSingleExitTunnels(t *testing.T) {
+	nonBest := map[string]interface{}{
+		"id":       int64(77),
+		"inNodeId": []map[string]interface{}{{"nodeId": int64(10)}},
+		"outNodeId": []map[string]interface{}{
+			{"nodeId": int64(30), "strategy": "round"},
+			{"nodeId": int64(31), "strategy": "round"},
+		},
+	}
+	if state, ok := buildBestExitDisplayState(nonBest, newBestExitManager(), testBestExitNameLookup(nil)); ok || state != nil {
+		t.Fatalf("expected non-best tunnel to skip state, got %+v", state)
+	}
+
+	singleExit := map[string]interface{}{
+		"id":       int64(78),
+		"inNodeId": []map[string]interface{}{{"nodeId": int64(10)}},
+		"outNodeId": []map[string]interface{}{
+			{"nodeId": int64(30), "strategy": tunnelStrategyBest},
+		},
+	}
+	if state, ok := buildBestExitDisplayState(singleExit, newBestExitManager(), testBestExitNameLookup(nil)); ok || state != nil {
+		t.Fatalf("expected single-exit tunnel to skip state, got %+v", state)
+	}
+}
+
+func testBestExitNameLookup(names map[int64]string) bestExitNodeNameLookup {
+	return func(nodeID int64) (string, bool) {
+		name := names[nodeID]
+		return name, name != ""
+	}
+}
+```
+
+- [ ] **Step 2: Run backend display tests to verify failure**
+
+Run from `go-backend`:
+
+```bash
+go test ./internal/http/handler -run 'TestBestExitDecisionSnapshot|TestBuildBestExitDisplayState' -count=1
+```
+
+Expected: FAIL with undefined `snapshot`, `buildBestExitDisplayState`, and `bestExitNodeNameLookup`.
+
+---
+
+### Task 2: Backend Display State Implementation
+
+**Files:**
+- Create: `go-backend/internal/http/handler/tunnel_best_exit_display.go`
+- Modify: `go-backend/internal/http/handler/tunnel_best_exit.go`
+- Test: `go-backend/internal/http/handler/tunnel_best_exit_display_test.go`
+
+- [ ] **Step 1: Implement display state and snapshot helpers**
+
+Create `go-backend/internal/http/handler/tunnel_best_exit_display.go`:
+
+```go
+package handler
+
+import (
+	"log"
+	"strings"
+)
+
+const (
+	bestExitDisplayStatusApplied = "applied"
+	bestExitDisplayStatusWaiting = "waiting"
+	bestExitDisplaySummaryMulti  = "多个出口"
+	bestExitDisplaySummaryWait   = "等待探测"
+	bestExitUnknownExitName      = "未知出口"
+	bestExitUnknownEntryName     = "未知入口"
+	bestExitUnknownChainName     = "未知中转"
+)
+
+type bestExitDecisionSnapshot struct {
+	AppliedExitNodeID int64
+	UpdatedAt         int64
+	Reason            string
+	Scores            []bestExitCandidateScore
+}
+
+type bestExitDisplayState struct {
+	Enabled   bool                  `json:"enabled"`
+	Summary   string                `json:"summary"`
+	Status    string                `json:"status"`
+	UpdatedAt int64                 `json:"updatedAt,omitempty"`
+	Reason    string                `json:"reason,omitempty"`
+	Items     []bestExitDisplayItem `json:"items"`
+}
+
+type bestExitDisplayItem struct {
+	OwnerNodeID   int64  `json:"ownerNodeId"`
+	OwnerNodeName string `json:"ownerNodeName"`
+	OwnerRole     string `json:"ownerRole"`
+	ExitNodeID    int64  `json:"exitNodeId,omitempty"`
+	ExitNodeName  string `json:"exitNodeName"`
+	UpdatedAt     int64  `json:"updatedAt,omitempty"`
+	Reason        string `json:"reason,omitempty"`
+}
+
+type bestExitNodeNameLookup func(nodeID int64) (string, bool)
+
+func (m *bestExitManager) snapshot(key bestExitOwnerKey) (bestExitDecisionSnapshot, bool) {
+	if m == nil {
+		return bestExitDecisionSnapshot{}, false
+	}
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	d := m.decisions[key]
+	if d == nil {
+		return bestExitDecisionSnapshot{}, false
+	}
+	updatedAt := int64(0)
+	if !d.LastSwitchAt.IsZero() {
+		updatedAt = d.LastSwitchAt.UnixMilli()
+	}
+	return bestExitDecisionSnapshot{
+		AppliedExitNodeID: d.AppliedExitNodeID,
+		UpdatedAt:         updatedAt,
+		Reason:            d.LastReason,
+		Scores:            cloneBestExitScores(d.Scores),
+	}, true
+}
+
+func (h *Handler) attachBestExitStates(items []map[string]interface{}) {
+	if h == nil || len(items) == 0 {
+		return
+	}
+	lookup := h.bestExitNodeNameLookup()
+	for _, item := range items {
+		state, ok := buildBestExitDisplayState(item, h.bestExit, lookup)
+		if !ok {
+			delete(item, "bestExitState")
+			continue
+		}
+		item["bestExitState"] = state
+	}
+}
+
+func (h *Handler) bestExitNodeNameLookup() bestExitNodeNameLookup {
+	cache := map[int64]string{}
+	return func(nodeID int64) (string, bool) {
+		if nodeID <= 0 || h == nil {
+			return "", false
+		}
+		if name, ok := cache[nodeID]; ok {
+			return name, name != ""
+		}
+		node, err := h.getNodeRecord(nodeID)
+		if err != nil || node == nil {
+			cache[nodeID] = ""
+			return "", false
+		}
+		name := strings.TrimSpace(node.Name)
+		cache[nodeID] = name
+		return name, name != ""
+	}
+}
+
+func buildBestExitDisplayState(tunnel map[string]interface{}, manager *bestExitManager, lookup bestExitNodeNameLookup) (*bestExitDisplayState, bool) {
+	if tunnel == nil {
+		return nil, false
+	}
+	tunnelID := asInt64(tunnel["id"], 0)
+	outNodes := bestExitDisplayMapSlice(tunnel["outNodeId"])
+	if tunnelID <= 0 || len(outNodes) <= 1 {
+		return nil, false
+	}
+	if !isBestTunnelStrategy(asString(outNodes[0]["strategy"])) {
+		return nil, false
+	}
+
+	owners, ownerRole := bestExitDisplayOwners(tunnel)
+	state := &bestExitDisplayState{
+		Enabled: true,
+		Summary: bestExitDisplaySummaryWait,
+		Status:  bestExitDisplayStatusWaiting,
+		Items:   make([]bestExitDisplayItem, 0, len(owners)),
+	}
+
+	exitsByID := map[int64]map[string]interface{}{}
+	for _, exit := range outNodes {
+		if id := asInt64(exit["nodeId"], 0); id > 0 {
+			exitsByID[id] = exit
+		}
+	}
+	appliedExitIDs := map[int64]string{}
+	appliedCount := 0
+	latestUpdatedAt := int64(0)
+	latestReason := ""
+	for _, owner := range owners {
+		ownerNodeID := asInt64(owner["nodeId"], 0)
+		if ownerNodeID <= 0 {
+			continue
+		}
+		item := bestExitDisplayItem{
+			OwnerNodeID:   ownerNodeID,
+			OwnerNodeName: bestExitDisplayNodeName(owner, ownerNodeID, lookup, bestExitUnknownOwnerName(ownerRole)),
+			OwnerRole:     ownerRole,
+			ExitNodeName:  bestExitDisplaySummaryWait,
+			Reason:        bestExitDisplayStatusWaiting,
+		}
+		if snapshot, ok := manager.snapshot(bestExitOwnerKey{TunnelID: tunnelID, OwnerNodeID: ownerNodeID}); ok && snapshot.AppliedExitNodeID > 0 {
+			item.ExitNodeID = snapshot.AppliedExitNodeID
+			item.ExitNodeName = bestExitDisplayNodeName(exitsByID[snapshot.AppliedExitNodeID], snapshot.AppliedExitNodeID, lookup, bestExitUnknownExitName)
+			item.UpdatedAt = snapshot.UpdatedAt
+			item.Reason = snapshot.Reason
+			appliedExitIDs[item.ExitNodeID] = item.ExitNodeName
+			appliedCount++
+			if snapshot.UpdatedAt > latestUpdatedAt {
+				latestUpdatedAt = snapshot.UpdatedAt
+				latestReason = snapshot.Reason
+			}
+		}
+		state.Items = append(state.Items, item)
+	}
+
+	if appliedCount == 0 {
+		return state, true
+	}
+	state.Status = bestExitDisplayStatusApplied
+	state.UpdatedAt = latestUpdatedAt
+	state.Reason = latestReason
+	if len(appliedExitIDs) == 1 {
+		for _, name := range appliedExitIDs {
+			state.Summary = name
+		}
+	} else {
+		state.Summary = bestExitDisplaySummaryMulti
+	}
+	return state, true
+}
+
+func bestExitDisplayOwners(tunnel map[string]interface{}) ([]map[string]interface{}, string) {
+	chainGroups := bestExitDisplayChainGroups(tunnel["chainNodes"])
+	if len(chainGroups) > 0 {
+		return chainGroups[len(chainGroups)-1], "chain"
+	}
+	return bestExitDisplayMapSlice(tunnel["inNodeId"]), "entry"
+}
+
+func bestExitDisplayMapSlice(v interface{}) []map[string]interface{} {
+	switch arr := v.(type) {
+	case []map[string]interface{}:
+		return arr
+	case []interface{}:
+		out := make([]map[string]interface{}, 0, len(arr))
+		for _, item := range arr {
+			if m, ok := item.(map[string]interface{}); ok {
+				out = append(out, m)
+			}
+		}
+		return out
+	default:
+		return nil
+	}
+}
+
+func bestExitDisplayChainGroups(v interface{}) [][]map[string]interface{} {
+	switch groups := v.(type) {
+	case [][]map[string]interface{}:
+		return groups
+	case []interface{}:
+		out := make([][]map[string]interface{}, 0, len(groups))
+		for _, group := range groups {
+			items := bestExitDisplayMapSlice(group)
+			if len(items) > 0 {
+				out = append(out, items)
+			}
+		}
+		return out
+	default:
+		return nil
+	}
+}
+
+func bestExitDisplayNodeName(source map[string]interface{}, nodeID int64, lookup bestExitNodeNameLookup, fallback string) string {
+	if source != nil {
+		for _, key := range []string{"nodeName", "name"} {
+			if name := strings.TrimSpace(asString(source[key])); name != "" {
+				return name
+			}
+		}
+	}
+	if lookup != nil {
+		if name, ok := lookup(nodeID); ok && strings.TrimSpace(name) != "" {
+			return strings.TrimSpace(name)
+		}
+	}
+	return fallback
+}
+
+func bestExitUnknownOwnerName(role string) string {
+	if role == "chain" {
+		return bestExitUnknownChainName
+	}
+	return bestExitUnknownEntryName
+}
+
+func (h *Handler) attachBestExitStatesOrLog(items []map[string]interface{}) {
+	defer func() {
+		if recovered := recover(); recovered != nil {
+			log.Printf("best_exit: attach display state failed: %v", recovered)
+		}
+	}()
+	h.attachBestExitStates(items)
+}
+```
+
+- [ ] **Step 2: Replace direct attach calls with panic-safe wrapper**
+
+Keep `attachBestExitStates` for tests, and use `attachBestExitStatesOrLog` from handlers in Task 3. This step only creates the function above; no handler wiring yet.
+
+- [ ] **Step 3: Run backend display tests**
+
+Run from `go-backend`:
+
+```bash
+go test ./internal/http/handler -run 'TestBestExitDecisionSnapshot|TestBuildBestExitDisplayState' -count=1
+```
+
+Expected: PASS.
+
+- [ ] **Step 4: Run gofmt**
+
+```bash
+gofmt -w internal/http/handler/tunnel_best_exit_display.go internal/http/handler/tunnel_best_exit_display_test.go
+```
+
+- [ ] **Step 5: Commit backend display implementation**
+
+```bash
+git add go-backend/internal/http/handler/tunnel_best_exit_display.go go-backend/internal/http/handler/tunnel_best_exit_display_test.go
+git commit -m "feat: build best exit display state"
+```
+
+---
+
+### Task 3: Attach Best-Exit State To Tunnel List And Get Responses
+
+**Files:**
+- Modify: `go-backend/internal/http/handler/handler.go`
+- Modify: `go-backend/internal/http/handler/mutations.go`
+- Test: `go-backend/internal/http/handler/tunnel_best_exit_display_test.go`
+
+- [ ] **Step 1: Write failing handler attach tests**
+
+Append to `go-backend/internal/http/handler/tunnel_best_exit_display_test.go`:
+
+```go
+func TestAttachBestExitStatesAddsStateToBestTunnelOnly(t *testing.T) {
+	h := &Handler{bestExit: newBestExitManager()}
+	now := time.Unix(300, 0)
+	h.bestExit.setApplied(bestExitOwnerKey{TunnelID: 77, OwnerNodeID: 10}, 30, now)
+
+	items := []map[string]interface{}{
+		{
+			"id":       int64(77),
+			"inNodeId": []map[string]interface{}{{"nodeId": int64(10)}},
+			"outNodeId": []map[string]interface{}{
+				{"nodeId": int64(30), "strategy": tunnelStrategyBest},
+				{"nodeId": int64(31), "strategy": tunnelStrategyBest},
+			},
+		},
+		{
+			"id":       int64(78),
+			"inNodeId": []map[string]interface{}{{"nodeId": int64(12)}},
+			"outNodeId": []map[string]interface{}{
+				{"nodeId": int64(40), "strategy": "round"},
+				{"nodeId": int64(41), "strategy": "round"},
+			},
+		},
+	}
+
+	h.attachBestExitStates(items)
+	state, ok := items[0]["bestExitState"].(*bestExitDisplayState)
+	if !ok {
+		t.Fatalf("expected bestExitState on best tunnel, got %#v", items[0]["bestExitState"])
+	}
+	if state.Summary != bestExitUnknownExitName || state.Items[0].ExitNodeID != 30 {
+		t.Fatalf("unexpected state with fallback names: %+v", state)
+	}
+	if _, exists := items[1]["bestExitState"]; exists {
+		t.Fatalf("non-best tunnel should not have bestExitState: %+v", items[1])
+	}
+}
+```
+
+- [ ] **Step 2: Run attach test to verify failure**
+
+Run from `go-backend`:
+
+```bash
+go test ./internal/http/handler -run TestAttachBestExitStatesAddsStateToBestTunnelOnly -count=1
+```
+
+Expected: PASS.
+
+- [ ] **Step 3: Wire tunnel list response**
+
+In `go-backend/internal/http/handler/handler.go`, change `tunnelList` from:
+
+```go
+	items, err := h.repo.ListTunnels()
+	if err != nil {
+		response.WriteJSON(w, response.Err(-2, err.Error()))
+		return
+	}
+	response.WriteJSON(w, response.OK(items))
+```
+
+to:
+
+```go
+	items, err := h.repo.ListTunnels()
+	if err != nil {
+		response.WriteJSON(w, response.Err(-2, err.Error()))
+		return
+	}
+	h.attachBestExitStatesOrLog(items)
+	response.WriteJSON(w, response.OK(items))
+```
+
+- [ ] **Step 4: Wire single tunnel response**
+
+In `go-backend/internal/http/handler/mutations.go`, change `tunnelGet` from:
+
+```go
+	items, err := h.repo.ListTunnels()
+	if err != nil {
+		response.WriteJSON(w, response.Err(-2, err.Error()))
+		return
+	}
+	for _, it := range items {
+		if asInt64(it["id"], 0) == id {
+			response.WriteJSON(w, response.OK(it))
+			return
+		}
+	}
+```
+
+to:
+
+```go
+	items, err := h.repo.ListTunnels()
+	if err != nil {
+		response.WriteJSON(w, response.Err(-2, err.Error()))
+		return
+	}
+	h.attachBestExitStatesOrLog(items)
+	for _, it := range items {
+		if asInt64(it["id"], 0) == id {
+			response.WriteJSON(w, response.OK(it))
+			return
+		}
+	}
+```
+
+- [ ] **Step 5: Run focused backend tests**
+
+Run from `go-backend`:
+
+```bash
+go test ./internal/http/handler -run 'TestBestExitDecisionSnapshot|TestBuildBestExitDisplayState|TestAttachBestExitStatesAddsStateToBestTunnelOnly' -count=1
+```
+
+Expected: PASS.
+
+- [ ] **Step 6: Run gofmt**
+
+```bash
+gofmt -w internal/http/handler/handler.go internal/http/handler/mutations.go internal/http/handler/tunnel_best_exit_display.go internal/http/handler/tunnel_best_exit_display_test.go
+```
+
+- [ ] **Step 7: Commit response wiring**
+
+```bash
+git add go-backend/internal/http/handler/handler.go go-backend/internal/http/handler/mutations.go go-backend/internal/http/handler/tunnel_best_exit_display.go go-backend/internal/http/handler/tunnel_best_exit_display_test.go
+git commit -m "feat: expose best exit display state"
+```
+
+---
+
+### Task 4: Frontend Tunnel List Display
+
+**Files:**
+- Modify: `vite-frontend/src/pages/tunnel.tsx`
+
+- [ ] **Step 1: Add TypeScript types**
+
+In `vite-frontend/src/pages/tunnel.tsx`, add these interfaces after `interface ChainTunnel`:
+
+```ts
+interface BestExitStateItem {
+  ownerNodeId: number;
+  ownerNodeName: string;
+  ownerRole: "entry" | "chain";
+  exitNodeId?: number;
+  exitNodeName: string;
+  updatedAt?: number;
+  reason?: string;
+}
+
+interface BestExitState {
+  enabled: boolean;
+  summary: string;
+  status: "applied" | "waiting";
+  updatedAt?: number;
+  reason?: string;
+  items: BestExitStateItem[];
+}
+```
+
+Then add the optional field to `interface Tunnel`:
+
+```ts
+  bestExitState?: BestExitState | null;
+```
+
+- [ ] **Step 2: Preserve API state during mapping**
+
+In `mapTunnelApiItems`, add `bestExitState` to the returned object:
+
+```ts
+    bestExitState:
+      tunnel.bestExitState && typeof tunnel.bestExitState === "object"
+        ? {
+            ...tunnel.bestExitState,
+            items: Array.isArray(tunnel.bestExitState.items)
+              ? tunnel.bestExitState.items
+              : [],
+          }
+        : null,
+```
+
+The mapped object should include this field before `createdTime` or immediately after it.
+
+- [ ] **Step 3: Add render helpers**
+
+Add these helper functions after `mapTunnelApiItems` and before `export default function TunnelPage()`:
+
+```tsx
+const bestExitOwnerRoleText = (role: BestExitStateItem["ownerRole"]) => {
+  return role === "chain" ? "中转" : "入口";
+};
+
+const bestExitDetailTitle = (state?: BestExitState | null) => {
+  if (!state?.enabled || !state.items?.length) {
+    return "";
+  }
+  return state.items
+    .map((item) => {
+      const ownerName = item.ownerNodeName || `${bestExitOwnerRoleText(item.ownerRole)} ${item.ownerNodeId}`;
+      const exitName = item.exitNodeName || "等待探测";
+      return `${ownerName} -> ${exitName}`;
+    })
+    .join("\n");
+};
+
+const renderBestExitState = (state?: BestExitState | null) => {
+  if (!state?.enabled) {
+    return null;
+  }
+  const title = bestExitDetailTitle(state);
+  const isWaiting = state.status === "waiting";
+
+  return (
+    <div
+      className={`mt-1 text-[11px] leading-4 ${
+        isWaiting
+          ? "text-default-500"
+          : "text-emerald-700 dark:text-emerald-300"
+      }`}
+      title={title || undefined}
+    >
+      最优出口：{state.summary || "等待探测"}
+    </div>
+  );
+};
+```
+
+- [ ] **Step 4: Render in table topology cell**
+
+In the table topology `<TableCell>` around line 1674, change the cell content from:
+
+```tsx
+                        <div className="flex items-center gap-1.5 text-xs">
+                          <span className="font-semibold text-primary-700 dark:text-primary-400">
+                            {tunnel.inNodeId?.length || 0}入口
+                          </span>
+                          <span className="text-default-400">→</span>
+                          <span className="font-semibold text-secondary-700 dark:text-secondary-400">
+                            {tunnel.type === 2
+                              ? tunnel.chainNodes?.length || 0
+                              : 0}
+                            跳
+                          </span>
+                          <span className="text-default-400">→</span>
+                          <span className="font-semibold text-success-700 dark:text-success-400">
+                            {tunnel.type === 2
+                              ? tunnel.outNodeId?.length || 0
+                              : tunnel.inNodeId?.length || 0}
+                            出口
+                          </span>
+                        </div>
+```
+
+to:
+
+```tsx
+                        <div>
+                          <div className="flex items-center gap-1.5 text-xs">
+                            <span className="font-semibold text-primary-700 dark:text-primary-400">
+                              {tunnel.inNodeId?.length || 0}入口
+                            </span>
+                            <span className="text-default-400">→</span>
+                            <span className="font-semibold text-secondary-700 dark:text-secondary-400">
+                              {tunnel.type === 2
+                                ? tunnel.chainNodes?.length || 0
+                                : 0}
+                              跳
+                            </span>
+                            <span className="text-default-400">→</span>
+                            <span className="font-semibold text-success-700 dark:text-success-400">
+                              {tunnel.type === 2
+                                ? tunnel.outNodeId?.length || 0
+                                : tunnel.inNodeId?.length || 0}
+                              出口
+                            </span>
+                          </div>
+                          {renderBestExitState(tunnel.bestExitState)}
+                        </div>
+```
+
+- [ ] **Step 5: Render in grid card topology section**
+
+In the grid card topology section, after the closing `</div>` for the topology row at the end of the block containing `出口` and before the enclosing border section closes, add:
+
+```tsx
+                                <div className="text-center">
+                                  {renderBestExitState(tunnel.bestExitState)}
+                                </div>
+```
+
+The result should put the best-exit summary under the entry -> hop -> exit row inside the topology section.
+
+- [ ] **Step 6: Run frontend build**
+
+Run from `vite-frontend`:
+
+```bash
+pnpm run build
+```
+
+Expected: PASS with `tsc && vite build` completing successfully.
+
+- [ ] **Step 7: Commit frontend display**
+
+```bash
+git add vite-frontend/src/pages/tunnel.tsx
+git commit -m "feat: show current best exit in tunnel list"
+```
+
+---
+
+### Task 5: Full Verification And Review
+
+**Files:**
+- Verify only.
+
+- [ ] **Step 1: Run backend tests**
+
+Run from `go-backend`:
+
+```bash
+go test ./...
+```
+
+Expected: PASS.
+
+- [ ] **Step 2: Run frontend build**
+
+Run from `vite-frontend`:
+
+```bash
+pnpm run build
+```
+
+Expected: PASS.
+
+- [ ] **Step 3: Inspect final diff**
+
+Run from repository root:
+
+```bash
+git diff --stat origin/main...HEAD
+git diff -- go-backend/internal/http/handler/tunnel_best_exit_display.go go-backend/internal/http/handler/tunnel_best_exit_display_test.go go-backend/internal/http/handler/handler.go go-backend/internal/http/handler/mutations.go vite-frontend/src/pages/tunnel.tsx
+```
+
+Expected: Diff only adds best-exit display state, response attachment, frontend list display, and tests. It must not change best-exit scoring, switching, runtime chain update, or agent code.
+
+- [ ] **Step 4: Request final code review**
+
+Ask a reviewer to check:
+
+```text
+Review the best-exit current display implementation. Confirm it only exposes current in-memory best-exit state in tunnel list/get responses and renders it in the tunnel list. Verify it does not change routing, scoring, switching, persistence, or polling behavior.
+```
+
+Expected: No blocking findings.
+
+---
+
+## Self-Review
+
+- Spec coverage: Backend response state is Task 2 and Task 3; direct vs final-hop owner semantics are covered by Task 1 tests; frontend list/grid display is Task 4; no polling and no routing changes are preserved by Task 5 review instructions.
+- Placeholder scan: The plan contains concrete files, function names, code blocks, commands, and expected outcomes.
+- Type consistency: `BestExitState`, `BestExitStateItem`, `bestExitDisplayState`, `bestExitDisplayItem`, `bestExitDecisionSnapshot`, and `bestExitNodeNameLookup` are defined before use and names match across tasks.