feat(tui-go): workflow-propose choice panel

Render a workflow.proposed frame as a single-select picker with a manual-answer
slot: ↑↓/jk to choose, enter to launch, e for custom, esc to peek away. Picking
a candidate sends StartSession (and focuses the launched session); the custom
slot continues the conversation via ChatInput. Reuses the modal helpers from the
clarification view.

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

@@ -0,0 +1,171 @@
+package app
+
+import (
+	"strings"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+	"github.com/correx/tui-go/internal/protocol"
+)
+
+// proposecard.go renders and drives the workflow-propose view: the router's triage
+// suggestion of candidate workflows, presented as a single-select picker with a
+// manual-answer slot (like a choice panel). Picking a candidate launches that
+// workflow seeded with the original request; the custom slot continues the chat.
+
+// --- widget state ---
+
+func (m *Model) proposeInitState() {
+	m.proposeCursor = 0
+	m.proposeText = ""
+	m.proposeTyping = false
+	m.proposeDismissed = false
+}
+
+// --- key handling ---
+
+func (m Model) handleProposeKey(k tea.KeyMsg) (tea.Model, tea.Cmd) {
+	s := m.session(m.selectedID)
+	if s == nil || s.Propose == nil {
+		return m, nil
+	}
+	if m.proposeTyping {
+		return m.handleProposeTyping(k)
+	}
+	n := len(s.Propose.Candidates) // index n == the custom slot
+	switch k.Type {
+	case tea.KeyEsc:
+		m.proposeDismissed = true
+	case tea.KeyUp:
+		m.proposeCursor = clampInt(m.proposeCursor-1, 0, n)
+	case tea.KeyDown:
+		m.proposeCursor = clampInt(m.proposeCursor+1, 0, n)
+	case tea.KeyEnter, tea.KeySpace:
+		return m.proposeSubmit()
+	case tea.KeyRunes:
+		switch string(k.Runes) {
+		case "k":
+			m.proposeCursor = clampInt(m.proposeCursor-1, 0, n)
+		case "j":
+			m.proposeCursor = clampInt(m.proposeCursor+1, 0, n)
+		case "e":
+			m.proposeCursor = n // jump to the custom slot and start typing
+			m.proposeTyping = true
+		}
+	}
+	return m, nil
+}
+
+func (m Model) handleProposeTyping(k tea.KeyMsg) (tea.Model, tea.Cmd) {
+	switch k.Type {
+	case tea.KeyEsc:
+		m.proposeTyping = false
+	case tea.KeyEnter:
+		return m.proposeSubmit() // commit the custom answer and send it as chat
+	case tea.KeyBackspace:
+		if len(m.proposeText) > 0 {
+			m.proposeText = m.proposeText[:len(m.proposeText)-1]
+		}
+	case tea.KeyRunes, tea.KeySpace:
+		m.proposeText += string(k.Runes)
+	}
+	return m, nil
+}
+
+// proposeSubmit acts on the focused row: a candidate launches its workflow (seeded
+// with the original request); the custom slot continues the conversation as a chat
+// turn. An empty custom slot just drops into typing rather than submitting nothing.
+func (m Model) proposeSubmit() (tea.Model, tea.Cmd) {
+	s := m.session(m.selectedID)
+	if s == nil || s.Propose == nil {
+		return m, nil
+	}
+	p := s.Propose
+	if m.proposeCursor >= len(p.Candidates) {
+		text := strings.TrimSpace(m.proposeText)
+		if text == "" {
+			m.proposeTyping = true
+			return m, nil
+		}
+		m.client.Send(protocol.ChatInput(p.SessionID, text, "CHAT"))
+		s.Propose = nil
+		m.proposeInitState()
+		return m, nil
+	}
+	pick := p.Candidates[m.proposeCursor]
+	m.client.Send(protocol.StartSession(pick.WorkflowID, p.OriginalRequest))
+	m.pendingWorkflowFocus = true // focus the launched session when it announces
+	s.Propose = nil
+	m.proposeInitState()
+	return m, nil
+}
+
+// --- rendering ---
+
+func (m Model) proposeModal() string {
+	t := m.theme
+	w := m.modalWidth()
+	s := m.session(m.selectedID)
+	if s == nil || s.Propose == nil {
+		return ""
+	}
+	p := s.Propose
+
+	var b strings.Builder
+	b.WriteString(m.titleLine("workflow suggestion") + "\n")
+	if p.OriginalRequest != "" {
+		b.WriteString(mbg(t, "  for: "+p.OriginalRequest, t.P.Faint) + "\n")
+	}
+	if p.Prompt != "" {
+		b.WriteString(mbg(t, "  "+p.Prompt, t.P.Fg) + "\n")
+	}
+	b.WriteString("\n")
+
+	contentW := w - 6
+	for i, c := range p.Candidates {
+		b.WriteString(m.proposeRow(c, i == m.proposeCursor, contentW) + "\n")
+	}
+	b.WriteString(m.proposeCustomRow(m.proposeCursor >= len(p.Candidates), contentW) + "\n")
+
+	b.WriteString("\n" + modalHints(t, [][2]string{
+		{"↑↓", "choose"}, {"enter", "launch"}, {"e", "custom"}, {"esc", "later"},
+	}))
+	return t.Overlay.Width(w).Render(b.String())
+}
+
+// proposeRow renders one candidate workflow: a focus marker, the [workflow-id] chip,
+// and its reason.
+func (m Model) proposeRow(c ProposeCandidate, focused bool, w int) string {
+	t := m.theme
+	marker := mbg(t, "  ", t.P.BgPanel)
+	reasonFg := t.P.Dim
+	if focused {
+		marker = lipgloss.NewStyle().Foreground(t.P.Accent).Background(t.P.BgPanel).Render("▸ ")
+		reasonFg = t.P.Fg
+	}
+	line := marker + lipgloss.NewStyle().Foreground(t.P.Accent2).Background(t.P.BgPanel).Render("["+c.WorkflowID+"]")
+	if c.Reason != "" {
+		line += mbg(t, " "+c.Reason, reasonFg)
+	}
+	return clip(line, w)
+}
+
+// proposeCustomRow renders the manual-answer slot: a prompt when empty, the typed
+// text (with a caret while editing) otherwise.
+func (m Model) proposeCustomRow(focused bool, w int) string {
+	t := m.theme
+	marker := mbg(t, "  ", t.P.BgPanel)
+	fg := t.P.Dim
+	if focused {
+		marker = lipgloss.NewStyle().Foreground(t.P.Accent).Background(t.P.BgPanel).Render("▸ ")
+		fg = t.P.Fg
+	}
+	label := "✎ something else…"
+	switch {
+	case m.proposeTyping:
+		label = "✎ " + m.proposeText + "▏"
+	case strings.TrimSpace(m.proposeText) != "":
+		label = "✎ " + m.proposeText
+	}
+	return clip(marker+lipgloss.NewStyle().Foreground(fg).Background(t.P.BgPanel).Render(label), w)
+}