feat(tui): workflow-start intent input box wired to StartSession.input

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

@@ -243,6 +243,12 @@ func (m Model) handleInsertKey(k tea.KeyMsg) (tea.Model, tea.Cmd) {
 		if m.inputMode == ModeFilter {
 			m.inputMode = ModeRouter
 		}
+		if m.inputMode == ModeIntent {
+			m.wfPendingID = ""
+			m.wfPendingName = ""
+			m.clearInput()
+			m.inputMode = ModeRouter
+		}
 	case tea.KeyEnter:
 		return m.submit()
 	case tea.KeyBackspace:
@@ -275,6 +281,19 @@ func (m Model) handleInsertKey(k tea.KeyMsg) (tea.Model, tea.Cmd) {
 	return m, nil
 }
 
+// beginIntent stashes the chosen workflow and switches to a text-entry prompt for the
+// freeform request. Submitting sends StartSession(id, intent); an empty line starts with no
+// intent (fixed-task workflows). Esc cancels.
+func (m *Model) beginIntent(wf Workflow) {
+	m.wfPendingID = wf.ID
+	m.wfPendingName = wf.ID
+	m.wfVisible = false
+	m.wfIndex = -1
+	m.clearInput()
+	m.editMode = ModeInsert
+	m.inputMode = ModeIntent
+}
+
 func (m *Model) enterInsert(mode InputMode) {
 	m.editMode = ModeInsert
 	m.inputMode = mode
@@ -296,11 +315,7 @@ func (m Model) normalEnter() (tea.Model, tea.Cmd) {
 		return m, nil
 	}
 	if m.wfVisible && m.wfIndex >= 0 && m.wfIndex < len(m.workflows) {
-		wf := m.workflows[m.wfIndex]
-		m.client.Send(protocol.StartSession(wf.ID))
-		m.wfVisible = false
-		m.wfIndex = -1
-		m.pendingWorkflowFocus = true
+		m.beginIntent(m.workflows[m.wfIndex])
 		return m, nil
 	}
 	if m.selectedID != "" {
@@ -537,12 +552,21 @@ func (m Model) submit() (tea.Model, tea.Cmd) {
 
 	switch ds {
 	case StateIdle:
-		// Workflow picker selection.
-		if m.wfIndex >= 0 && m.wfIndex < len(m.workflows) {
-			wf := m.workflows[m.wfIndex]
-			m.wfIndex = -1
-			m.client.Send(protocol.StartSession(wf.ID))
+		// Intent line for a workflow being started.
+		if m.wfPendingID != "" {
+			id := m.wfPendingID
+			m.client.Send(protocol.StartSession(id, text))
+			m.wfPendingID = ""
+			m.wfPendingName = ""
 			m.clearInput()
+			m.inputMode = ModeRouter
+			m.editMode = ModeNormal
+			m.pendingWorkflowFocus = true
+			return m, nil
+		}
+		// Workflow picker selection → prompt for the request first.
+		if m.wfIndex >= 0 && m.wfIndex < len(m.workflows) {
+			m.beginIntent(m.workflows[m.wfIndex])
 			return m, nil
 		}
 		// Entering an already-selected session (blank submit).