fix(tui): approval nav lockups, shell non-diff preview, hint dedup

Three QA-found issues in the approval gate:

- displayState gated the in-session/approval surfaces on hasApproval
  before sessionEntered, so moving the list cursor onto a session with a
  pending gate auto-opened it, and `l` back-to-list couldn't escape
  (the gate re-popped). Require sessionEntered first.
- The band ran every preview through the two-column diff renderer, so a
  shell tool's argv JSON rendered as an identical-column "diff". Detect
  real unified diffs (isUnifiedDiff); render other previews as plain
  text, and drop the ^x fullscreen hint when there's nothing to expand.
- The footer duplicated the band's approve/reject/steer/diff keys. It now
  shows navigation (l back / e events / q quit) instead.

apps/tui-go/internal/app/demo.go

@@ -84,6 +84,25 @@ func PreviewFrame(kind string, w, h int) string {
 			}
 		}
 
+	case "approval-shell":
+		m.connected = true
+		m.currentModel = "llama-cpp:default"
+		m.sessions = sampleSessions()
+		m.selectedID = "04a546aa"
+		m.sessionEntered = true
+		if s := m.session("04a546aa"); s != nil {
+			s.CurrentStage = "execute_script"
+			s.Events = sampleEvents()
+			s.Pending = &Approval{
+				RequestID: "req-2", SessionID: "04a546aa", Tier: "T2", Risk: "MEDIUM",
+				ToolName: "shell",
+				Preview:  `{"argv":["bash","scripts/healthcheck.sh"]}`,
+				Rationale: []string{
+					"[INTERPRETER_EXECUTION] Tool 'shell' invokes interpreter 'bash'",
+				},
+			}
+		}
+
 	case "diff":
 		m.connected = true
 		m.currentModel = "llama-cpp:default"

apps/tui-go/internal/app/diff.go

@@ -78,6 +78,48 @@ func parseUnifiedDiff(diff string) []diffRow {
 	return rows
 }
 
+// isUnifiedDiff reports whether s looks like a unified diff (file/hunk headers)
+// rather than arbitrary preview text such as a shell argv JSON. Non-diff previews
+// must not go through the two-column renderer (it would show identical columns).
+func isUnifiedDiff(s string) bool {
+	return strings.Contains(s, "@@ -") || strings.HasPrefix(s, "--- ") || strings.Contains(s, "\n--- ")
+}
+
+// previewPlainLines splits non-diff preview text into display lines.
+func previewPlainLines(s string) []string {
+	return strings.Split(strings.TrimRight(s, "\n"), "\n")
+}
+
+// previewRowCount is the number of content rows a preview occupies — diff rows
+// for a real diff, plain lines otherwise. Drives band sizing and scroll bounds.
+func previewRowCount(s string) int {
+	if isUnifiedDiff(s) {
+		return len(parseUnifiedDiff(s))
+	}
+	return len(previewPlainLines(s))
+}
+
+// renderPreviewLines renders non-diff preview text as dim plain lines (single
+// column), up to maxRows starting at off, each truncated to width.
+func (m Model) renderPreviewLines(content string, width, maxRows, off int) []string {
+	lines := previewPlainLines(content)
+	if off < 0 {
+		off = 0
+	}
+	if off > len(lines) {
+		off = len(lines)
+	}
+	end := off + maxRows
+	if end > len(lines) {
+		end = len(lines)
+	}
+	out := make([]string, 0, end-off)
+	for _, ln := range lines[off:end] {
+		out = append(out, m.theme.span(truncate(ln, width), m.theme.P.Dim))
+	}
+	return out
+}
+
 // hunkStarts reads the starting old/new line numbers from an @@ -a,b +c,d @@ marker.
 func hunkStarts(h string) (int, int) {
 	old, newer := 1, 1

apps/tui-go/internal/app/model.go

@@ -210,25 +210,21 @@ func NewModel(client *ws.Client) Model {
 	}
 }
 
-// displayState derives the active screen, matching the Kotlin extension.
+// displayState derives the active screen. A session must be *entered*
+// (sessionEntered) before its in-session or approval surfaces show — otherwise
+// merely moving the list cursor onto a session with a pending gate would yank
+// you into the approval, and `l` back-to-list couldn't escape it.
 func (m Model) displayState() DisplayState {
-	if m.selectedID == "" {
+	if m.selectedID == "" || !m.sessionEntered {
 		return StateIdle
 	}
-	hasApproval := false
+	if m.approvalDismissed {
+		return StateInSession
+	}
 	if s := m.session(m.selectedID); s != nil && s.Pending != nil {
-		hasApproval = true
-	}
-	switch {
-	case m.approvalDismissed:
-		return StateInSession
-	case hasApproval:
 		return StateApproval
-	case m.sessionEntered:
-		return StateInSession
-	default:
-		return StateIdle
 	}
+	return StateInSession
 }
 
 func (m Model) session(id string) *Session {

apps/tui-go/internal/app/overlays.go

@@ -58,7 +58,7 @@ func mbg(t Theme, s string, fg lipgloss.Color) string {
 func (m Model) approvalBandHeight() int {
 	rows, rat := 0, 0
 	if s := m.session(m.selectedID); s != nil && s.Pending != nil {
-		rows = len(parseUnifiedDiff(s.Pending.Preview))
+		rows = previewRowCount(s.Pending.Preview)
 		if n := len(s.Pending.Rationale); n > 0 {
 			rat = n + 1 // rationale lines + trailing blank
 		}
@@ -114,8 +114,6 @@ func (m Model) renderApprovalBand(h int) string {
 	if diffH < 1 {
 		diffH = 1
 	}
-	rows := parseUnifiedDiff(a.Preview)
-
 	body := make([]string, 0, innerH)
 	body = append(body, m.justify(leftHdr, rightHdr, textW, t.P.Bg), "")
 	for _, r := range a.Rationale {
@@ -125,8 +123,14 @@ func (m Model) renderApprovalBand(h int) string {
 	if len(a.Rationale) > 0 {
 		body = append(body, "")
 	}
+	var content []string
+	if isUnifiedDiff(a.Preview) {
+		content = m.renderSplitDiff(parseUnifiedDiff(a.Preview), textW, diffH, 0)
+	} else {
+		content = m.renderPreviewLines(a.Preview, textW, diffH, 0)
+	}
 	diffStart := len(body)
-	body = append(body, m.renderSplitDiff(rows, textW, diffH, 0)...)
+	body = append(body, content...)
 	for len(body) < diffStart+diffH {
 		body = append(body, "")
 	}
@@ -150,8 +154,11 @@ func (m Model) approvalActions() string {
 		return lipgloss.NewStyle().Foreground(t.P.Accent).Background(t.P.Bg).Bold(true).Render(k) +
 			t.span(" "+l, t.P.Faint)
 	}
-	parts := []string{hint("a", "approve"), hint("A", "auto"), hint("s", "steer"),
-		hint("r", "reject"), hint("^x", "fullscreen"), hint("esc", "later")}
+	parts := []string{hint("a", "approve"), hint("A", "auto"), hint("s", "steer"), hint("r", "reject")}
+	if s := m.session(m.selectedID); s != nil && s.Pending != nil && isUnifiedDiff(s.Pending.Preview) {
+		parts = append(parts, hint("^x", "fullscreen"))
+	}
+	parts = append(parts, hint("esc", "later"))
 	return strings.Join(parts, t.span("   ", t.P.Faint))
 }
 
@@ -167,8 +174,7 @@ func (m Model) diffBodyHeight() int {
 // diffMaxScroll is the largest scroll offset that still fills the body with
 // diff rows, keeping the last page anchored to the bottom of the modal.
 func (m Model) diffMaxScroll() int {
-	rows := parseUnifiedDiff(m.currentDiff())
-	max := len(rows) - m.diffBodyHeight()
+	max := previewRowCount(m.currentDiff()) - m.diffBodyHeight()
 	if max < 0 {
 		max = 0
 	}
@@ -180,7 +186,7 @@ func (m Model) diffModal() string {
 	w := m.modalWidth()
 	bodyH := m.diffBodyHeight()
 	diff := m.currentDiff()
-	rows := parseUnifiedDiff(diff)
+	isDiff := isUnifiedDiff(diff)
 
 	off := m.diffScrollOffset
 	if off > m.diffMaxScroll() {
@@ -191,12 +197,22 @@ func (m Model) diffModal() string {
 	}
 
 	var b strings.Builder
-	b.WriteString(m.titleLine("diff"))
+	title := "preview"
+	if isDiff {
+		title = "diff"
+	}
+	b.WriteString(m.titleLine(title))
 	if tgt := diffTarget(diff); tgt != "" {
 		b.WriteString(mbg(t, "  "+tgt, t.P.Dim))
 	}
-	b.WriteString(mbg(t, "   ("+itoa(len(rows))+" rows)", t.P.Faint) + "\n\n")
-	for _, ln := range m.renderSplitDiff(rows, w-6, bodyH, off) {
+	b.WriteString(mbg(t, "   ("+itoa(previewRowCount(diff))+" rows)", t.P.Faint) + "\n\n")
+	var lines []string
+	if isDiff {
+		lines = m.renderSplitDiff(parseUnifiedDiff(diff), w-6, bodyH, off)
+	} else {
+		lines = m.renderPreviewLines(diff, w-6, bodyH, off)
+	}
+	for _, ln := range lines {
 		b.WriteString(ln + "\n")
 	}
 	b.WriteString("\n" + modalHints(t, [][2]string{{"↑↓", "scroll"}, {"^x/esc", "close"}}))

apps/tui-go/internal/app/view.go

@@ -139,7 +139,8 @@ func (m Model) renderFooter() string {
 	case m.editMode == ModeInsert:
 		hints = []string{hint("enter", "send"), hint("esc", "normal"), hint("↑↓", "history")}
 	case m.displayState() == StateApproval:
-		hints = []string{hint("a", "approve"), hint("A", "auto"), hint("s", "steer"), hint("r", "reject"), hint("x", "diff"), hint("esc", "later")}
+		// Approval actions live in the band itself; the footer offers navigation only.
+		hints = []string{hint("l", "back"), hint("e", "events"), hint("q", "quit")}
 	case m.displayState() == StateIdle:
 		hints = []string{hint("i", "name"), hint("/", "filter"), hint("enter", "open"), hint("jk", "move"), hint("w", "workflows"), hint("p", "cmds"), hint("q", "quit")}
 	default: // StateInSession