feat(cli): always show login URL during auth login with copy support

When the browser opens during `auth login`, the login URL is now always
displayed so users can copy or navigate to it manually. Pressing 'c'
copies the URL to the system clipboard.

Closes #2990

Signed-off-by: Miguel Martinez Trivino <miguel@chainloop.dev>

Author: migmartri

app/cli/cmd/auth_login.go

@@ -1,5 +1,5 @@
 //
-// Copyright 2024 The Chainloop Authors.
+// Copyright 2024-2026 The Chainloop Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -23,6 +23,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"os"
 	"os/exec"
 	"runtime"
 	"time"
@@ -32,6 +33,7 @@ import (
 	jwt "github.com/golang-jwt/jwt/v4"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
+	"golang.org/x/term"
 )
 
 type app struct {
@@ -87,11 +89,25 @@ func interactiveAuth(forceHeadless bool) error {
 
 	a.serverChan = make(chan error)
 
-	// Run server in background
+	loginURLStr := serverLoginURL.String()
+	fmt.Println()
+	fmt.Println("  Browser didn't open? Use the URL below to sign in (press c to copy):")
+	fmt.Println()
+	fmt.Printf("  %s\n", loginURLStr)
+	fmt.Println()
+	fmt.Println("  Waiting for authentication to complete...")
+
+	// Save terminal state before raw mode so we can restore it reliably.
+	// The keypress goroutine may be blocked on stdin.Read when auth completes,
+	// so its deferred restore won't run until the process exits.
+	fd := int(os.Stdin.Fd())
+	termState, _ := term.GetState(fd)
+
+	done := make(chan struct{})
+	go listenForCopyKeypress(loginURLStr, done)
+
 	http.HandleFunc(callbackURL.Path, a.handleCallback)
 	go func() {
-		logger.Info().Msg("waiting for the authentication to be completed, please check your browser")
-
 		server := &http.Server{ReadHeaderTimeout: time.Second}
 
 		err := server.Serve(listener)
@@ -101,6 +117,10 @@ func interactiveAuth(forceHeadless bool) error {
 	}()
 
 	err = <-a.serverChan
+	close(done)
+	if termState != nil {
+		term.Restore(fd, termState)
+	}
 	if err != nil {
 		return err
 	}
@@ -206,3 +226,47 @@ func localListenerAndCallbackURL() (net.Listener, *url.URL, error) {
 	callbackURL := &url.URL{Scheme: "http", Host: listener.Addr().String(), Path: "/auth/callback"}
 	return listener, callbackURL, nil
 }
+
+const ctrlC = 3
+
+// listenForCopyKeypress puts the terminal in raw mode and listens for
+// 'c' keypress to copy the URL to the system clipboard.
+func listenForCopyKeypress(urlStr string, done <-chan struct{}) {
+	fd := int(os.Stdin.Fd())
+
+	oldState, err := term.MakeRaw(fd)
+	if err != nil {
+		return
+	}
+	defer term.Restore(fd, oldState)
+
+	buf := make([]byte, 1)
+	for {
+		select {
+		case <-done:
+			return
+		default:
+		}
+
+		n, err := os.Stdin.Read(buf)
+		if err != nil || n == 0 {
+			return
+		}
+
+		switch buf[0] {
+		case 'c', 'C':
+			term.Restore(fd, oldState)
+			if err := copyToClipboard(urlStr); err != nil {
+				fmt.Println("  Could not copy to clipboard. Please copy the URL manually.")
+			} else {
+				fmt.Println("  Copied to clipboard!")
+			}
+			oldState, err = term.MakeRaw(fd)
+			if err != nil {
+				return
+			}
+		case ctrlC:
+			return
+		}
+	}
+}

app/cli/cmd/clipboard.go

@@ -0,0 +1,54 @@
+//
+// Copyright 2026 The Chainloop Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmd
+
+import (
+	"fmt"
+	"os/exec"
+	"runtime"
+	"strings"
+)
+
+func copyToClipboard(text string) error {
+	var name string
+	var args []string
+
+	switch runtime.GOOS {
+	case "darwin":
+		name = "pbcopy"
+	case "windows":
+		name = "clip"
+	default:
+		// Linux: try xclip first, then xsel
+		for _, candidate := range [][]string{
+			{"xclip", "-selection", "clipboard"},
+			{"xsel", "--clipboard", "--input"},
+		} {
+			if _, err := exec.LookPath(candidate[0]); err == nil {
+				name = candidate[0]
+				args = candidate[1:]
+				break
+			}
+		}
+		if name == "" {
+			return fmt.Errorf("no clipboard tool available (install xclip or xsel)")
+		}
+	}
+
+	cmd := exec.Command(name, args...)
+	cmd.Stdin = strings.NewReader(text)
+	return cmd.Run()
+}