fix(generate-entry): detect distro from the image, not the box name

Signed-off-by: Luca Di Maio <luca.dimaio1@gmail.com>

pkg/commands/generate_entry.go

@@ -126,7 +126,20 @@ func (c *GenerateEntryCommand) resolveTargets(
 		}
 		return names, images, "auto", nil
 	case opts.ContainerName != "":
-		return []string{opts.ContainerName}, nil, opts.Icon, nil
+		// Look up the container's image so auto-detection keys off the distro
+		// (image) rather than the box name: a box named "dev" running
+		// Ubuntu should still get the Ubuntu icon. Non-fatal if the manager
+		// can't be reached — we fall back to the name in Execute.
+		images := map[string]string{}
+		if listResult, err := c.listCommand.Execute(ctx); err == nil {
+			for _, container := range listResult.Containers {
+				if container.Name == opts.ContainerName {
+					images[opts.ContainerName] = container.Image
+					break
+				}
+			}
+		}
+		return []string{opts.ContainerName}, images, opts.Icon, nil
 	default:
 		return []string{defaultContainerName}, nil, opts.Icon, nil
 	}

pkg/commands/generate_entry_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -11,7 +12,9 @@ import (
 
 	"github.com/89luca89/distrobox/pkg/commands"
 	"github.com/89luca89/distrobox/pkg/config"
+	"github.com/89luca89/distrobox/pkg/containermanager"
 	"github.com/89luca89/distrobox/pkg/containermanager/providers"
+	"github.com/89luca89/distrobox/pkg/internal/testutil"
 )
 
 func TestGenerateEntryCommand_Execute(t *testing.T) {
@@ -184,3 +187,35 @@ func TestGenerateAllEntriesCommand_Execute(t *testing.T) {
 		assert.NoFileExists(t, expectedEntryPath)
 	}
 }
+
+// single-container generate-entry detects the distro from the container's
+// image, not its name. A box named "dev" running Ubuntu gets the Ubuntu icon.
+func TestGenerateEntryCommand_SingleModeUsesImageHint(t *testing.T) {
+	tempDir := t.TempDir()
+
+	mock := &testutil.MockContainerManager{
+		ListContainersResult: []containermanager.Container{
+			{
+				Name:   "dev",
+				Image:  "docker.io/library/ubuntu:22.04",
+				Status: "Exited",
+				Labels: map[string]string{"manager": "distrobox"},
+			},
+		},
+	}
+	listCmd := commands.NewListCommand(&config.Values{}, mock)
+	cmd := commands.NewGenerateEntryCommand(&config.Values{}, listCmd)
+
+	err := cmd.Execute(context.Background(), &commands.GenerateEntryOptions{
+		ContainerName:       "dev",
+		Icon:                "auto",
+		DesktopEntryBaseDir: tempDir,
+		DistroboxPath:       "/usr/bin/distrobox",
+	})
+	require.NoError(t, err)
+
+	content, err := os.ReadFile(filepath.Join(tempDir, "applications", "dev.desktop"))
+	require.NoError(t, err)
+	assert.Contains(t, string(content), "ubuntu-distrobox.png",
+		"single-mode must key auto-detection off the image, not the box name 'dev'")
+}