diff --git a/apps/tui-go/internal/app/demo.go b/apps/tui-go/internal/app/demo.go
index 07a591d1..eb5fa09c 100644
--- a/apps/tui-go/internal/app/demo.go
+++ b/apps/tui-go/internal/app/demo.go
@@ -75,9 +75,12 @@ func PreviewFrame(kind string, w, h int) string {
 			s.CurrentStage = "write_script"
 			s.Events = sampleEvents()
 			s.Pending = &Approval{
-				RequestID: "req-1", SessionID: "04a546aa", Tier: "T3", Risk: "HIGH",
+				RequestID: "req-1", SessionID: "04a546aa", Tier: "T3", Risk: "MEDIUM",
 				ToolName: "file_write",
 				Preview:  "--- a/healthcheck.sh\n+++ b/healthcheck.sh\n@@ -0,0 +1,4 @@\n+#!/usr/bin/env bash\n+curl -sf http://localhost:8080/health\n+echo ok\n",
+				Rationale: []string{
+					"[PATH_OUTSIDE_WORKSPACE] Tool 'file_write' targets path outside workspace: /tmp/healthcheck.sh",
+				},
 			}
 		}
 
diff --git a/apps/tui-go/internal/app/model.go b/apps/tui-go/internal/app/model.go
index db177f59..49608692 100644
--- a/apps/tui-go/internal/app/model.go
+++ b/apps/tui-go/internal/app/model.go
@@ -91,6 +91,9 @@ type Approval struct {
 	Risk      string
 	ToolName  string
 	Preview   string
+	// Rationale holds the plane-2 verified preconditions ("[PATH_OUTSIDE_WORKSPACE] …")
+	// that justify the gate — shown in the approval band instead of an opaque tier.
+	Rationale []string
 }
 
 // Session is the UI's view of one server session.
@@ -129,13 +132,13 @@ type Model struct {
 	reconnecting bool
 
 	// sessions
-	sessions     []Session
-	selectedID   string
-	filter       string
-	workflows    []Workflow
-	wfIndex      int // -1 = not in workflow picker
-	wfVisible    bool
-	bgUpdates    int
+	sessions   []Session
+	selectedID string
+	filter     string
+	workflows  []Workflow
+	wfIndex    int // -1 = not in workflow picker
+	wfVisible  bool
+	bgUpdates  int
 
 	// input
 	editMode     EditMode
@@ -147,9 +150,9 @@ type Model struct {
 	savedBuffer  string
 
 	// flow flags
-	sessionEntered        bool
-	approvalDismissed     bool
-	pendingWorkflowFocus  bool
+	sessionEntered       bool
+	approvalDismissed    bool
+	pendingWorkflowFocus bool
 
 	// router transcript
 	routerMessages  map[string][]RouterEntry
diff --git a/apps/tui-go/internal/app/overlays.go b/apps/tui-go/internal/app/overlays.go
index e3af420b..a13e7405 100644
--- a/apps/tui-go/internal/app/overlays.go
+++ b/apps/tui-go/internal/app/overlays.go
@@ -56,11 +56,14 @@ func mbg(t Theme, s string, fg lipgloss.Color) string {
 // never crowds out the session above (longer diffs spill to the ^x fullscreen
 // view). Layout: 2 borders + header + blank + diff rows + blank + action row.
 func (m Model) approvalBandHeight() int {
-	rows := 0
+	rows, rat := 0, 0
 	if s := m.session(m.selectedID); s != nil && s.Pending != nil {
 		rows = len(parseUnifiedDiff(s.Pending.Preview))
+		if n := len(s.Pending.Rationale); n > 0 {
+			rat = n + 1 // rationale lines + trailing blank
+		}
 	}
-	h := 2 + 1 + 1 + rows + 1 + 1
+	h := 2 + 1 + 1 + rat + rows + 1 + 1
 	if maxH := m.height * 55 / 100; h > maxH {
 		h = maxH
 	}
@@ -103,7 +106,11 @@ func (m Model) renderApprovalBand(h int) string {
 		lipgloss.NewStyle().Foreground(riskColor).Background(t.P.Bg).Bold(true).Render(strings.ToUpper(a.Risk))
 
 	innerH := h - 2
-	diffH := innerH - 4 // header, blank, blank, action row
+	ratBlock := 0
+	if len(a.Rationale) > 0 {
+		ratBlock = len(a.Rationale) + 1 // rationale lines + trailing blank
+	}
+	diffH := innerH - 4 - ratBlock // header, blank, blank, action row, + rationale block
 	if diffH < 1 {
 		diffH = 1
 	}
@@ -111,8 +118,16 @@ func (m Model) renderApprovalBand(h int) string {
 
 	body := make([]string, 0, innerH)
 	body = append(body, m.justify(leftHdr, rightHdr, textW, t.P.Bg), "")
+	for _, r := range a.Rationale {
+		marker := lipgloss.NewStyle().Foreground(t.P.Warn).Background(t.P.Bg).Render("▲ ")
+		body = append(body, marker+t.span(truncate(r, textW-2), t.P.Dim))
+	}
+	if len(a.Rationale) > 0 {
+		body = append(body, "")
+	}
+	diffStart := len(body)
 	body = append(body, m.renderSplitDiff(rows, textW, diffH, 0)...)
-	for len(body) < 2+diffH {
+	for len(body) < diffStart+diffH {
 		body = append(body, "")
 	}
 	body = append(body, "", m.approvalActions())
diff --git a/apps/tui-go/internal/app/server.go b/apps/tui-go/internal/app/server.go
index 31d3790d..df8b9854 100644
--- a/apps/tui-go/internal/app/server.go
+++ b/apps/tui-go/internal/app/server.go
@@ -261,8 +261,10 @@ func (m *Model) onSessionAnnounced(msg protocol.ServerMessage) {
 
 func (m *Model) onApprovalRequired(msg protocol.ServerMessage) {
 	risk := "unknown"
+	var rationale []string
 	if msg.RiskSummary != nil {
 		risk = msg.RiskSummary.Level
+		rationale = msg.RiskSummary.Rationale
 	}
 	info := &Approval{
 		RequestID: msg.RequestID,
@@ -271,6 +273,7 @@ func (m *Model) onApprovalRequired(msg protocol.ServerMessage) {
 		Risk:      risk,
 		ToolName:  deref(&msg.ToolName),
 		Preview:   derefp(msg.Preview),
+		Rationale: rationale,
 	}
 	if s := m.session(msg.SessionID); s != nil {
 		s.Pending = info
diff --git a/apps/tui-go/internal/protocol/golden_test.go b/apps/tui-go/internal/protocol/golden_test.go
index f9d9b198..b427f508 100644
--- a/apps/tui-go/internal/protocol/golden_test.go
+++ b/apps/tui-go/internal/protocol/golden_test.go
@@ -58,6 +58,22 @@ func TestDecodeGoldenServerFrames(t *testing.T) {
 				}
 			},
 		},
+		{
+			// Plane-2 rationale (verified preconditions) must survive decode — it is the
+			// justification shown in the approval band, not the opaque tier.
+			name:      "approval.required carries plane-2 rationale",
+			json:      `{"type":"approval.required","sessionId":"s1","requestId":"req-1","tier":"T3","riskSummary":{"level":"MEDIUM","factors":[],"recommendedAction":"PROMPT_USER","rationale":["[PATH_OUTSIDE_WORKSPACE] outside: /tmp/x"]},"toolName":"file_write","preview":"--- a/x\n+++ b/x","sequence":12,"sessionSequence":3}`,
+			wantType:  TypeApprovalRequired,
+			eventBear: true,
+			check: func(t *testing.T, m ServerMessage) {
+				if m.RiskSummary == nil {
+					t.Fatalf("approval.required: riskSummary decoded nil")
+				}
+				if len(m.RiskSummary.Rationale) != 1 || m.RiskSummary.Rationale[0] != "[PATH_OUTSIDE_WORKSPACE] outside: /tmp/x" {
+					t.Fatalf("rationale not decoded: %+v", m.RiskSummary)
+				}
+			},
+		},
 		{
 			name:      "snapshot_complete (non-event control frame)",
 			json:      `{"type":"snapshot_complete"}`,
diff --git a/apps/tui-go/internal/protocol/protocol.go b/apps/tui-go/internal/protocol/protocol.go
index 2fea4a86..1887d220 100644
--- a/apps/tui-go/internal/protocol/protocol.go
+++ b/apps/tui-go/internal/protocol/protocol.go
@@ -110,6 +110,7 @@ type RiskSummaryDto struct {
 	Level             string   `json:"level"`
 	Factors           []string `json:"factors"`
 	RecommendedAction string   `json:"recommendedAction"`
+	Rationale         []string `json:"rationale"`
 }
 
 type AssessedIssueDto struct {