feat: add "Start building" escape option to planning questions

Every planning question now shows a final option to skip remaining
questions and start building immediately. If the user has already
answered some questions, generates a plan from what's collected.
If no answers yet, goes straight to the agent with the raw prompt.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: halfaipg

chat.go

@@ -564,6 +564,42 @@ func (m *chatModel) handlePlanAnswer(input string) tea.Cmd {
 		return nil
 	}
 
+	// "Start building" — skip remaining questions, go to plan generation
+	if answer == AnswerStartBuilding {
+		m.segments = append(m.segments, segment{
+			kind: "user",
+			text: "  " + styleUserLabel.Render("  → ") + "Start building\n",
+		})
+		m.planState.CurrentQ = nil
+		m.planState.Done = true
+		m.rebuildViewport()
+
+		// If we have any Q&A, generate a plan; otherwise go straight to agent
+		if len(m.planState.QAHistory) > 0 {
+			m.notify.Push(Notification{Type: NotifyProgress, Text: "Generating plan..."})
+			glue := m.glue
+			ps := m.planState
+			return func() tea.Msg {
+				plan := glue.GeneratePlan(ps.OriginalPrompt, ps.QAHistory)
+				return planGeneratedMsg{plan: plan}
+			}
+		}
+
+		// No Q&A at all — skip plan, go straight to agent
+		m.segments = append(m.segments, segment{
+			kind: "text",
+			text: styleMuted.Render("  Skipping plan. Starting agent...\n\n"),
+		})
+		m.input.Placeholder = "describe what you want to build..."
+		original := m.planState.OriginalPrompt
+		m.planState = nil
+		m.startAgent(original)
+		return tea.Batch(
+			m.waitForEvent(),
+			tea.Tick(10*time.Second, func(t time.Time) tea.Msg { return narrateTickMsg{} }),
+		)
+	}
+
 	// Show the answer
 	m.segments = append(m.segments, segment{
 		kind: "user",

plan.go

@@ -261,6 +261,8 @@ func FormatQuestion(q *PlanQuestion, questionNum int) string {
 		sb.WriteString(label + "\n")
 	}
 
+	sb.WriteString(fmt.Sprintf("\n  [%d] Start building — skip remaining questions\n", len(q.Options)+1))
+
 	hint := "\n  Type a number to select"
 	if q.Type == "multiselect" {
 		hint = "\n  Type numbers separated by commas (e.g. 1,3)"
@@ -271,13 +273,24 @@ func FormatQuestion(q *PlanQuestion, questionNum int) string {
 	return sb.String()
 }
 
+// AnswerStartBuilding is returned by ParseAnswer when the user picks "Start building".
+const AnswerStartBuilding = "__START_BUILDING__"
+
 // ParseAnswer interprets user input as option selection(s) or free text.
+// Returns AnswerStartBuilding if the user chose the "Start building" escape option.
 func ParseAnswer(input string, q *PlanQuestion) string {
 	input = strings.TrimSpace(input)
 	if input == "" {
 		return input
 	}
 
+	// Check for the "Start building" escape option (last number)
+	skipIdx := len(q.Options) + 1
+	var parsed int
+	if _, err := fmt.Sscanf(input, "%d", &parsed); err == nil && parsed == skipIdx {
+		return AnswerStartBuilding
+	}
+
 	// Try to parse as number(s)
 	parts := strings.Split(input, ",")
 	var selectedLabels []string

plan_test.go

@@ -104,6 +104,30 @@ func TestFormatQuestion(t *testing.T) {
 	if !strings.Contains(formatted, "Stateless") {
 		t.Error("should contain option description")
 	}
+	if !strings.Contains(formatted, "[3] Start building") {
+		t.Error("should contain Start building escape option")
+	}
+}
+
+func TestParseAnswerStartBuilding(t *testing.T) {
+	q := &PlanQuestion{
+		Options: []PlanOption{
+			{ID: "opt1", Label: "Option A"},
+			{ID: "opt2", Label: "Option B"},
+		},
+	}
+
+	// Picking the last number (len+1) should return the sentinel
+	answer := ParseAnswer("3", q)
+	if answer != AnswerStartBuilding {
+		t.Errorf("expected AnswerStartBuilding, got %q", answer)
+	}
+
+	// Regular options still work
+	answer = ParseAnswer("1", q)
+	if answer != "Option A" {
+		t.Errorf("expected 'Option A', got %q", answer)
+	}
 }
 
 func TestFormatQuestionMultiselect(t *testing.T) {