headed in the right direction. Needs tests and to be cleaned up. This is a working example of the teams design combined with https://github.com/cli/cli/pull/4859#issuecomment-1012776582

pkg/cmd/repo/default/default.go

@@ -0,0 +1,129 @@
+package base
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+
+	"github.com/MakeNowJust/heredoc"
+	"github.com/cli/cli/v2/api"
+	"github.com/cli/cli/v2/context"
+	"github.com/cli/cli/v2/git"
+	"github.com/cli/cli/v2/internal/ghrepo"
+	"github.com/cli/cli/v2/pkg/cmdutil"
+	"github.com/cli/cli/v2/pkg/iostreams"
+	"github.com/spf13/cobra"
+)
+
+type DefaultOptions struct {
+	IO         *iostreams.IOStreams
+	Remotes    func() (context.Remotes, error)
+	BaseRepo   func() (ghrepo.Interface, error)
+	HttpClient func() (*http.Client, error)
+
+	RemoteName string
+	ListFlag   bool
+}
+
+func NewCmdDefault(f *cmdutil.Factory, runF func(*DefaultOptions) error) *cobra.Command {
+	opts := &DefaultOptions{
+		IO:         f.IOStreams,
+		HttpClient: f.HttpClient,
+		BaseRepo:   f.BaseRepo,
+		Remotes:    f.Remotes,
+	}
+
+	cmd := &cobra.Command{
+		Use:   "default <git remote name>",
+		Short: "Configure the default repository used for various commands",
+		Long: heredoc.Doc(`
+		The default repository is used to determine which repository gh
+		should automatically query for the commands:
+			issue, pr, browse, run, repo rename, secret, workflow
+		`),
+		Example: heredoc.Doc(`
+			$ gh repo default upstream
+		`),
+		Args: cobra.MaximumNArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			if len(args) > 0 {
+				opts.RemoteName = args[0]
+			}
+			if !opts.IO.CanPrompt() && !opts.ListFlag && opts.RemoteName == "" {
+				return cmdutil.FlagErrorf("remote name is required when not running interactively, use `--list` to see available remotes")
+			}
+			if err := cmdutil.MutuallyExclusive(
+				"args cannot be passed in with --list",
+				opts.RemoteName != "",
+				opts.ListFlag,
+			); err != nil {
+				return err
+			}
+
+			if runF != nil {
+				return runF(opts)
+			}
+			return defaultRun(opts)
+		},
+	}
+
+	cmd.Flags().BoolVarP(&opts.ListFlag, "list", "l", false, "list the current and available repositories")
+	return cmd
+}
+
+func defaultRun(opts *DefaultOptions) error {
+	remotes, err := opts.Remotes()
+	if err != nil {
+		return err
+	}
+
+	if opts.ListFlag {
+		found := false
+		list := &strings.Builder{}
+		for _, remote := range remotes {
+			if remote.Resolved == "base" {
+				list.WriteString(fmt.Sprintf("* %s\n", remote.Remote.Name))
+				found = true
+			} else {
+				list.WriteString(fmt.Sprintf("  %s\n", remote.Remote.Name))
+			}
+		}
+		if !found {
+			fmt.Fprint(opts.IO.Out, "the default repo has not been set\n")
+		}
+		fmt.Fprint(opts.IO.Out, list.String())
+		return nil
+	}
+
+	if opts.RemoteName != "" {
+		for _, remote := range remotes {
+			if opts.RemoteName == remote.Remote.Name {
+				removeBaseRepo(remotes)
+				git.SetRemoteResolution(remote.Name, "base")
+				return nil
+			}
+		}
+		return fmt.Errorf("could not find local remote name %s", opts.RemoteName)
+	}
+	removeBaseRepo(remotes)
+	httpClient, err := opts.HttpClient()
+	if err != nil {
+		return err
+	}
+	apiClient := api.NewClientFromHTTP(httpClient)
+	repoContext, err := context.ResolveRemotesToRepos(remotes, apiClient, "")
+	if err != nil {
+		return err
+	}
+	_, err = repoContext.BaseRepo(opts.IO)
+	return err
+}
+
+func removeBaseRepo(remotes context.Remotes) {
+	for _, remote := range remotes {
+		if remote.Resolved == "base" {
+			remote.Resolved = ""
+			git.UnsetRemoteResolution(remote.Remote.Name)
+		}
+	}
+}