cli: render hints from errors that carry them

Hooks the new internal/hint package into the CLI and plugin error renderers.
After printing the error itself, walks the chain for any error implementing hint.Hinter and prints its hint on its own line.
Preserves the underlying cause when cobra flag errors are converted to cli.StatusError so hint metadata can still be discovered.
t call sites
that don't carry a hint.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: David Karlsson <35727626+dvdksn@users.noreply.github.com>

Author: dvdksn

cli-plugins/plugin/plugin.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"os"
 	"sync"
 
@@ -14,6 +15,7 @@ import (
 	"github.com/docker/cli/cli/command"
 	"github.com/docker/cli/cli/connhelper"
 	"github.com/docker/cli/cli/debug"
+	"github.com/docker/cli/internal/hint"
 	"github.com/moby/moby/client"
 	"github.com/spf13/cobra"
 	"go.opentelemetry.io/otel"
@@ -104,14 +106,21 @@ func Run(makeCmd func(command.Cli) *cobra.Command, meta metadata.Metadata, ops .
 			if stErr.StatusCode == 0 { // FIXME(thaJeztah): this should never be used with a zero status-code. Check if we do this anywhere.
 				stErr.StatusCode = 1
 			}
-			_, _ = fmt.Fprintln(dockerCLI.Err(), stErr)
+			printError(dockerCLI.Err(), stErr)
 			os.Exit(stErr.StatusCode)
 		}
-		_, _ = fmt.Fprintln(dockerCLI.Err(), err)
+		printError(dockerCLI.Err(), err)
 		os.Exit(1)
 	}
 }
 
+func printError(out io.Writer, err error) {
+	_, _ = fmt.Fprintln(out, err)
+	if h := hint.Of(err); h != "" {
+		_, _ = fmt.Fprintln(out, "\n"+h)
+	}
+}
+
 func withPluginClientConn(name string) command.CLIOption {
 	return func(cli *command.DockerCli) error {
 		cmd := "docker"

cli/cobra.go

@@ -82,6 +82,7 @@ func FlagErrorFunc(cmd *cobra.Command, err error) error {
 	}
 
 	return StatusError{
+		Cause:      err,
 		Status:     fmt.Sprintf("%s\n\nUsage:  %s\n\nRun '%s --help' for more information", err, cmd.UseLine(), cmd.CommandPath()),
 		StatusCode: 125,
 	}

cmd/docker/docker.go

@@ -24,6 +24,7 @@ import (
 	cliflags "github.com/docker/cli/cli/flags"
 	"github.com/docker/cli/cli/version"
 	platformsignals "github.com/docker/cli/cmd/docker/internal/signals"
+	"github.com/docker/cli/internal/hint"
 	"github.com/moby/moby/client/pkg/versions"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
@@ -48,6 +49,9 @@ func main() {
 	if err != nil && !errdefs.IsCanceled(err) {
 		if err.Error() != "" {
 			_, _ = fmt.Fprintln(os.Stderr, err)
+			if h := hint.Of(err); h != "" {
+				_, _ = fmt.Fprintln(os.Stderr, "\n"+h)
+			}
 		}
 		os.Exit(getExitCode(err))
 	}