Fix sidebar agent click zones mapping all lines to first agent

buildAgentClickZones used lipgloss.Width()==0 to detect blank separator
lines between agent blocks, but TabStyle.Width() pads all lines with
whitespace, so separator lines had non-zero width. This caused every
agent line to be mapped to the first agent, making clicking on any
agent other than the first one impossible.

Replace the check with isVisuallyBlank() which strips ANSI codes and
checks for whitespace-only content. Add regression test.

Assisted-By: docker-agent

Author: dgageot

pkg/tui/components/sidebar/agent_click_test.go

@@ -0,0 +1,54 @@
+package sidebar
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/docker/docker-agent/pkg/runtime"
+	"github.com/docker/docker-agent/pkg/session"
+	"github.com/docker/docker-agent/pkg/tui/service"
+)
+
+func TestSidebar_HandleClickType_Agent(t *testing.T) {
+	t.Parallel()
+
+	sess := session.New()
+	sessionState := service.NewSessionState(sess)
+	sessionState.SetCurrentAgentName("agent1")
+	sb := New(sessionState)
+
+	m := sb.(*model)
+	m.sessionHasContent = true
+	m.titleGenerated = true
+	m.sessionTitle = "Test"
+	m.currentAgent = "agent1"
+	m.availableAgents = []runtime.AgentDetails{
+		{Name: "agent1", Provider: "openai", Model: "gpt-4", Description: "First agent"},
+		{Name: "agent2", Provider: "anthropic", Model: "claude", Description: "Second agent"},
+	}
+	m.width = 40
+	m.height = 50
+
+	// Force a render to populate agentClickZones
+	_ = sb.View()
+
+	paddingLeft := m.layoutCfg.PaddingLeft
+
+	// Verify clicking on agent1 lines returns ClickAgent with "agent1"
+	foundAgent1 := false
+	foundAgent2 := false
+	for y := range len(m.cachedLines) {
+		result, agentName := sb.HandleClickType(paddingLeft+2, y)
+		if result == ClickAgent {
+			if agentName == "agent1" {
+				foundAgent1 = true
+			}
+			if agentName == "agent2" {
+				foundAgent2 = true
+			}
+		}
+	}
+	assert.True(t, foundAgent1, "should be able to click on agent1")
+	assert.True(t, foundAgent2, "should be able to click on agent2")
+}

pkg/tui/components/sidebar/sidebar.go

@@ -13,6 +13,7 @@ import (
 	"charm.land/bubbles/v2/textinput"
 	tea "charm.land/bubbletea/v2"
 	"charm.land/lipgloss/v2"
+	"github.com/charmbracelet/x/ansi"
 
 	"github.com/docker/docker-agent/pkg/paths"
 	"github.com/docker/docker-agent/pkg/runtime"
@@ -1214,6 +1215,13 @@ func (m *model) renderAgentEntry(content *strings.Builder, agent runtime.AgentDe
 	content.WriteString(toolcommon.TruncateText("Model: "+agent.Model, maxWidth))
 }
 
+// isVisuallyBlank returns true if a rendered line contains no visible content.
+// Lines may contain ANSI escape codes and whitespace padding from lipgloss styles
+// (e.g., TabStyle.Width()), so we strip ANSI sequences and check for whitespace.
+func isVisuallyBlank(line string) bool {
+	return strings.TrimSpace(ansi.Strip(line)) == ""
+}
+
 // buildAgentClickZones populates agentClickZones by scanning the rendered lines
 // to find which lines belong to which agent. It relies on the structure produced
 // by renderTab + agentInfo: a 2-line tab header, then agent blocks separated by
@@ -1230,7 +1238,7 @@ func (m *model) buildAgentClickZones(agentSectionStart int, lines []string) {
 	inBlock := false
 
 	for i := agentSectionStart + tabHeaderLines; i < len(lines) && agentIdx < len(m.availableAgents); i++ {
-		if lipgloss.Width(lines[i]) == 0 {
+		if isVisuallyBlank(lines[i]) {
 			// Blank line: if we were inside a block, advance to the next agent
 			if inBlock {
 				agentIdx++