Replace git CLI fetch with go-git using new credential helper

cmd/entire/cli/git_operations.go

@@ -8,10 +8,12 @@ import (
 	"strings"
 	"time"
 
+	"github.com/entireio/cli/cmd/entire/cli/gitauth"
 	"github.com/entireio/cli/cmd/entire/cli/paths"
 	"github.com/entireio/cli/cmd/entire/cli/strategy"
 
 	"github.com/go-git/go-git/v6"
+	"github.com/go-git/go-git/v6/config"
 	"github.com/go-git/go-git/v6/plumbing"
 )
 
@@ -310,31 +312,36 @@ func ValidateBranchName(ctx context.Context, branchName string) error {
 }
 
 // FetchAndCheckoutRemoteBranch fetches a branch from origin and creates a local tracking branch.
-// Uses git CLI instead of go-git for fetch because go-git doesn't use credential helpers,
-// which breaks HTTPS URLs that require authentication.
+// Uses go-git with credential helper / SSH agent auth.
 func FetchAndCheckoutRemoteBranch(ctx context.Context, branchName string) error {
-	// Validate branch name before using in shell command (branchName comes from user CLI input)
 	if err := ValidateBranchName(ctx, branchName); err != nil {
 		return err
 	}
 
-	// Use git CLI for fetch (go-git's fetch can be tricky with auth)
 	ctx, cancel := context.WithTimeout(ctx, 2*time.Minute)
 	defer cancel()
 
-	refSpec := fmt.Sprintf("+refs/heads/%s:refs/remotes/origin/%s", branchName, branchName)
+	repo, err := openRepository(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to open repository: %w", err)
+	}
+
+	remoteURL := gitauth.RemoteURL(repo, "origin")
+	auth := gitauth.ResolveAuth(ctx, remoteURL)
 
-	fetchCmd := exec.CommandContext(ctx, "git", "fetch", "origin", refSpec)
-	if output, err := fetchCmd.CombinedOutput(); err != nil {
+	refSpec := config.RefSpec(fmt.Sprintf("+refs/heads/%s:refs/remotes/origin/%s", branchName, branchName))
+	err = repo.FetchContext(ctx, &git.FetchOptions{
+		RemoteName: "origin",
+		RefSpecs:   []config.RefSpec{refSpec},
+		Auth:       auth,
+		Tags:       git.NoTags,
+		Force:      true,
+	})
+	if err != nil && !errors.Is(err, git.NoErrAlreadyUpToDate) {
 		if ctx.Err() == context.DeadlineExceeded {
 			return errors.New("fetch timed out after 2 minutes")
 		}
-		return fmt.Errorf("failed to fetch branch from origin: %s: %w", strings.TrimSpace(string(output)), err)
-	}
-
-	repo, err := openRepository(ctx)
-	if err != nil {
-		return fmt.Errorf("failed to open repository: %w", err)
+		return fmt.Errorf("failed to fetch branch from origin: %w", err)
 	}
 
 	// Get the remote branch reference
@@ -345,8 +352,7 @@ func FetchAndCheckoutRemoteBranch(ctx context.Context, branchName string) error
 
 	// Create local branch pointing to the same commit
 	localRef := plumbing.NewHashReference(plumbing.NewBranchReferenceName(branchName), remoteRef.Hash())
-	err = repo.Storer.SetReference(localRef)
-	if err != nil {
+	if err := repo.Storer.SetReference(localRef); err != nil {
 		return fmt.Errorf("failed to create local branch: %w", err)
 	}
 
@@ -356,28 +362,34 @@ func FetchAndCheckoutRemoteBranch(ctx context.Context, branchName string) error
 
 // FetchMetadataBranch fetches the entire/checkpoints/v1 branch from origin and creates/updates the local branch.
 // This is used when the metadata branch exists on remote but not locally.
-// Uses git CLI instead of go-git for fetch because go-git doesn't use credential helpers,
-// which breaks HTTPS URLs that require authentication.
+// Uses go-git with credential helper / SSH agent auth.
 func FetchMetadataBranch(ctx context.Context) error {
 	branchName := paths.MetadataBranchName
 
-	// Use git CLI for fetch (go-git's fetch can be tricky with auth)
 	ctx, cancel := context.WithTimeout(ctx, 2*time.Minute)
 	defer cancel()
 
-	refSpec := fmt.Sprintf("+refs/heads/%s:refs/remotes/origin/%s", branchName, branchName)
+	repo, err := openRepository(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to open repository: %w", err)
+	}
+
+	remoteURL := gitauth.RemoteURL(repo, "origin")
+	auth := gitauth.ResolveAuth(ctx, remoteURL)
 
-	fetchCmd := exec.CommandContext(ctx, "git", "fetch", "origin", refSpec)
-	if output, err := fetchCmd.CombinedOutput(); err != nil {
+	refSpec := config.RefSpec(fmt.Sprintf("+refs/heads/%s:refs/remotes/origin/%s", branchName, branchName))
+	err = repo.FetchContext(ctx, &git.FetchOptions{
+		RemoteName: "origin",
+		RefSpecs:   []config.RefSpec{refSpec},
+		Auth:       auth,
+		Tags:       git.NoTags,
+		Force:      true,
+	})
+	if err != nil && !errors.Is(err, git.NoErrAlreadyUpToDate) {
 		if ctx.Err() == context.DeadlineExceeded {
 			return errors.New("fetch timed out after 2 minutes")
 		}
-		return fmt.Errorf("failed to fetch %s from origin: %s: %w", branchName, strings.TrimSpace(string(output)), err)
-	}
-
-	repo, err := openRepository(ctx)
-	if err != nil {
-		return fmt.Errorf("failed to open repository: %w", err)
+		return fmt.Errorf("failed to fetch %s from origin: %w", branchName, err)
 	}
 
 	// Get the remote branch reference

cmd/entire/cli/gitauth/auth.go

@@ -0,0 +1,140 @@
+// Package gitauth resolves transport.AuthMethod for go-git operations.
+//
+// It checks for git credential helpers (for HTTPS) and SSH agent (for SSH),
+// so that go-git fetch/push operations can authenticate without shelling out
+// to the git CLI.
+package gitauth
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"net/url"
+	"os"
+	"os/exec"
+	"strings"
+	"time"
+
+	git "github.com/go-git/go-git/v6"
+	"github.com/go-git/go-git/v6/plumbing/transport"
+	githttp "github.com/go-git/go-git/v6/plumbing/transport/http"
+	gitssh "github.com/go-git/go-git/v6/plumbing/transport/ssh"
+)
+
+// credentialHelperTimeout is the max time to wait for a credential helper.
+const credentialHelperTimeout = 5 * time.Second
+
+// ResolveAuth returns a transport.AuthMethod suitable for the given remote URL.
+//
+// For HTTPS URLs it attempts to use the git credential helper. For SSH URLs
+// (including SCP format) it uses the SSH agent. Returns nil if no auth can be
+// resolved, which allows unauthenticated access (e.g. public repos).
+func ResolveAuth(ctx context.Context, remoteURL string) transport.AuthMethod { //nolint:ireturn // must return interface for go-git FetchOptions.Auth
+	if remoteURL == "" {
+		return nil
+	}
+
+	if IsSSHURL(remoteURL) {
+		return resolveSSHAuth()
+	}
+
+	// HTTPS (or other non-SSH)
+	return resolveHTTPAuth(ctx, remoteURL)
+}
+
+// IsSSHURL returns true if the URL uses SSH protocol.
+// Supports SCP format (git@host:path) and ssh:// URLs.
+func IsSSHURL(rawURL string) bool {
+	// SCP format: git@github.com:org/repo.git
+	// Has ":" but no "://" scheme separator.
+	if strings.Contains(rawURL, ":") && !strings.Contains(rawURL, "://") {
+		return true
+	}
+	// ssh:// protocol
+	return strings.HasPrefix(rawURL, "ssh://")
+}
+
+// resolveHTTPAuth runs `git credential fill` to obtain HTTPS credentials.
+func resolveHTTPAuth(ctx context.Context, remoteURL string) transport.AuthMethod { //nolint:ireturn // returns *githttp.BasicAuth or nil
+	u, err := url.Parse(remoteURL)
+	if err != nil {
+		return nil
+	}
+
+	protocol := u.Scheme
+	host := u.Host // includes port if present
+	if protocol == "" || host == "" {
+		return nil
+	}
+
+	ctx, cancel := context.WithTimeout(ctx, credentialHelperTimeout)
+	defer cancel()
+
+	input := fmt.Sprintf("protocol=%s\nhost=%s\n\n", protocol, host)
+
+	cmd := exec.CommandContext(ctx, "git", "credential", "fill")
+	cmd.Stdin = strings.NewReader(input)
+	cmd.Env = append(os.Environ(), "GIT_TERMINAL_PROMPT=0")
+
+	var stdout, stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	if err := cmd.Run(); err != nil {
+		return nil
+	}
+
+	username, password := parseCredentialOutput(stdout.String())
+	if username == "" && password == "" {
+		return nil
+	}
+
+	return &githttp.BasicAuth{
+		Username: username,
+		Password: password,
+	}
+}
+
+// parseCredentialOutput extracts username and password from `git credential fill` output.
+func parseCredentialOutput(output string) (string, string) {
+	var username, password string
+	for line := range strings.SplitSeq(output, "\n") {
+		line = strings.TrimSpace(line)
+		if k, v, ok := strings.Cut(line, "="); ok {
+			switch k {
+			case "username":
+				username = v
+			case "password":
+				password = v
+			}
+		}
+	}
+	return username, password
+}
+
+// RemoteURL returns the first configured URL for the named remote.
+// Returns empty string if the remote doesn't exist or has no URLs.
+func RemoteURL(repo *git.Repository, remoteName string) string {
+	remote, err := repo.Remote(remoteName)
+	if err != nil {
+		return ""
+	}
+	cfg := remote.Config()
+	if len(cfg.URLs) == 0 {
+		return ""
+	}
+	return cfg.URLs[0]
+}
+
+// resolveSSHAuth returns an SSH agent auth method if an agent is available.
+func resolveSSHAuth() transport.AuthMethod { //nolint:ireturn // returns *gitssh.PublicKeysCallback or nil
+	if os.Getenv("SSH_AUTH_SOCK") == "" {
+		return nil
+	}
+
+	auth, err := gitssh.NewSSHAgentAuth("git")
+	if err != nil {
+		return nil
+	}
+	return auth
+}

cmd/entire/cli/gitauth/auth_test.go

@@ -0,0 +1,95 @@
+package gitauth
+
+import (
+	"context"
+	"testing"
+)
+
+func TestIsSSHURL(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		url  string
+		want bool
+	}{
+		{"SCP format", "git@github.com:org/repo.git", true},
+		{"SSH protocol", "ssh://git@github.com/org/repo.git", true},
+		{"HTTPS", "https://github.com/org/repo.git", false},
+		{"HTTP", "http://github.com/org/repo.git", false},
+		{"empty", "", false},
+		{"SCP with port", "git@github.com:22:org/repo.git", true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			if got := IsSSHURL(tt.url); got != tt.want {
+				t.Errorf("IsSSHURL(%q) = %v, want %v", tt.url, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestParseCredentialOutput(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name         string
+		output       string
+		wantUsername string
+		wantPassword string
+	}{
+		{
+			name:         "standard output",
+			output:       "protocol=https\nhost=github.com\nusername=token\npassword=ghp_xxx\n",
+			wantUsername: "token",
+			wantPassword: "ghp_xxx",
+		},
+		{
+			name:         "empty output",
+			output:       "",
+			wantUsername: "",
+			wantPassword: "",
+		},
+		{
+			name:         "no credentials",
+			output:       "protocol=https\nhost=github.com\n",
+			wantUsername: "",
+			wantPassword: "",
+		},
+		{
+			name:         "only username",
+			output:       "username=myuser\n",
+			wantUsername: "myuser",
+			wantPassword: "",
+		},
+		{
+			name:         "password with equals sign",
+			output:       "username=user\npassword=abc=def\n",
+			wantUsername: "user",
+			wantPassword: "abc=def",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			gotUser, gotPass := parseCredentialOutput(tt.output)
+			if gotUser != tt.wantUsername {
+				t.Errorf("username = %q, want %q", gotUser, tt.wantUsername)
+			}
+			if gotPass != tt.wantPassword {
+				t.Errorf("password = %q, want %q", gotPass, tt.wantPassword)
+			}
+		})
+	}
+}
+
+func TestResolveAuth_EmptyURL(t *testing.T) {
+	t.Parallel()
+	auth := ResolveAuth(context.Background(), "")
+	if auth != nil {
+		t.Error("expected nil auth for empty URL")
+	}
+}