diff --git a/internal/proxmox/bootstrap_test.go b/internal/proxmox/bootstrap_test.go
index fcc6db1..cfd5483 100644
--- a/internal/proxmox/bootstrap_test.go
+++ b/internal/proxmox/bootstrap_test.go
@@ -5,10 +5,12 @@ import (
 	"context"
 	"errors"
 	"log/slog"
+	"net"
 	"os"
 	"path/filepath"
 	"strings"
 	"testing"
+	"time"
 
 	"golang.org/x/crypto/ssh"
 )
@@ -330,3 +332,159 @@ func TestDeployPubKey_WhitespaceOnlyPubLine(t *testing.T) {
 		t.Error("expected error for whitespace-only pub line")
 	}
 }
+
+func TestBootstrapProxmox_FullFlow_IdempotentReRun(t *testing.T) {
+	srv := newFakeSSHServer(t)
+	defer srv.close()
+
+	home := t.TempDir()
+	t.Setenv("ORCA_HOME", home)
+	if err := os.WriteFile(filepath.Join(home, "known_hosts"), []byte{}, 0o600); err != nil {
+		t.Fatalf("create known_hosts: %v", err)
+	}
+
+	orig := sshDialer
+	defer func() { sshDialer = orig }()
+	origRunner := sessionRunner
+	defer func() { sessionRunner = origRunner }()
+
+	host, _, _ := net.SplitHostPort(srv.addr())
+	sshDialer = &funcDialer{fn: func(ctx context.Context, network, addr string, config *ssh.ClientConfig) (*ssh.Client, error) {
+		return fakeSSHClient(t, srv), nil
+	}}
+
+	for i := 0; i < 2; i++ {
+		sessionRunner = nil
+		if _, err := BootstrapProxmox(t.Context(), Options{
+			Host:     host,
+			Password: "pw",
+		}); err != nil {
+			t.Fatalf("bootstrap run %d: %v", i+1, err)
+		}
+	}
+}
+
+func TestBootstrapProxmox_FullFlow_NoPasswordInLogs(t *testing.T) {
+	srv := newFakeSSHServer(t)
+	defer srv.close()
+
+	home := t.TempDir()
+	t.Setenv("ORCA_HOME", home)
+	if err := os.WriteFile(filepath.Join(home, "known_hosts"), []byte{}, 0o600); err != nil {
+		t.Fatalf("create known_hosts: %v", err)
+	}
+
+	orig := sshDialer
+	defer func() { sshDialer = orig }()
+	origRunner := sessionRunner
+	defer func() { sessionRunner = origRunner }()
+	sessionRunner = nil
+	sshDialer = &staticDialer{client: fakeSSHClient(t, srv)}
+
+	host, _, _ := net.SplitHostPort(srv.addr())
+
+	var logBuf bytes.Buffer
+	_, err := BootstrapProxmox(t.Context(), Options{
+		Host:     host,
+		Password: "super-secret-pw-12345",
+		Logger:   slog.New(slog.NewTextHandler(&logBuf, nil)),
+	})
+	if err != nil {
+		t.Fatalf("BootstrapProxmox: %v", err)
+	}
+	out := logBuf.String()
+	if strings.Contains(out, "super-secret-pw-12345") {
+		t.Errorf("password leaked into logs (D-031): %s", out)
+	}
+}
+
+func TestBootstrapProxmox_FullFlow_ValidateSudoersFails(t *testing.T) {
+	srv := newFakeSSHServer(t)
+	defer srv.close()
+	srv.forceSudoersInvalid = true
+
+	home := t.TempDir()
+	t.Setenv("ORCA_HOME", home)
+	if err := os.WriteFile(filepath.Join(home, "known_hosts"), []byte{}, 0o600); err != nil {
+		t.Fatalf("create known_hosts: %v", err)
+	}
+
+	orig := sshDialer
+	defer func() { sshDialer = orig }()
+	origRunner := sessionRunner
+	defer func() { sessionRunner = origRunner }()
+	sessionRunner = nil
+	sshDialer = &staticDialer{client: fakeSSHClient(t, srv)}
+
+	host, _, _ := net.SplitHostPort(srv.addr())
+
+	_, err := BootstrapProxmox(t.Context(), Options{
+		Host:     host,
+		Password: "pw",
+	})
+	if err == nil {
+		t.Fatal("expected error for invalid sudoers")
+	}
+	if !strings.Contains(err.Error(), "validate sudoers") {
+		t.Errorf("error should mention validate sudoers, got: %v", err)
+	}
+}
+
+func TestDefaultSSHDialer_DialContext_ConnectionRefused(t *testing.T) {
+	d := defaultSSHDialer{}
+	cfg := &ssh.ClientConfig{
+		User:            "root",
+		Auth:            []ssh.AuthMethod{ssh.Password("pw")},
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+		Timeout:         200 * time.Millisecond,
+	}
+	_, err := d.DialContext(context.Background(), "tcp", "127.0.0.1:1", cfg)
+	if err == nil {
+		t.Fatal("expected error for connection refused")
+	}
+}
+
+func TestBootstrapProxmox_FullFlow_CreateLinuxUserFails(t *testing.T) {
+	srv := newFakeSSHServer(t)
+	defer srv.close()
+
+	home := t.TempDir()
+	t.Setenv("ORCA_HOME", home)
+	if err := os.WriteFile(filepath.Join(home, "known_hosts"), []byte{}, 0o600); err != nil {
+		t.Fatalf("create known_hosts: %v", err)
+	}
+
+	orig := sshDialer
+	defer func() { sshDialer = orig }()
+	origRunner := sessionRunner
+	defer func() { sessionRunner = origRunner }()
+	sessionRunner = nil
+	sshDialer = &staticDialer{client: fakeSSHClient(t, srv)}
+
+	host, _, _ := net.SplitHostPort(srv.addr())
+
+	// ProxmoxUser=root exercises the /root home branch in deployPubKey.
+	_, err := BootstrapProxmox(t.Context(), Options{
+		Host:        host,
+		Password:    "pw",
+		ProxmoxUser: "root",
+	})
+	if err != nil {
+		t.Fatalf("BootstrapProxmox with ProxmoxUser=root: %v", err)
+	}
+}
+
+func TestSSHSessionRunner_CombinedOutput_NewSessionError(t *testing.T) {
+	srv := newFakeSSHServer(t)
+	defer srv.close()
+	conn := fakeSSHClient(t, srv)
+	conn.Close()
+	r := &sshSessionRunner{client: conn}
+	_, err := r.CombinedOutput("echo hi")
+	if err == nil {
+		t.Fatal("expected error from NewSession on closed client")
+	}
+	if !strings.Contains(err.Error(), "new session") {
+		t.Errorf("error should mention new session, got: %v", err)
+	}
+}
diff --git a/internal/proxmox/ssh_session_test.go b/internal/proxmox/ssh_session_test.go
index a2941a0..178a87d 100644
--- a/internal/proxmox/ssh_session_test.go
+++ b/internal/proxmox/ssh_session_test.go
@@ -23,9 +23,10 @@ type fakeSSHServer struct {
 	config   *ssh.ServerConfig
 	done     chan struct{}
 
-	mu      sync.Mutex
-	state   map[string]string
-	authDir string
+	mu                  sync.Mutex
+	state               map[string]string
+	authDir             string
+	forceSudoersInvalid bool
 }
 
 func newFakeSSHServer(t *testing.T) *fakeSSHServer {
@@ -142,10 +143,11 @@ func (s *fakeSSHServer) runCommand(cmd string) ([]byte, int) {
 	case strings.HasPrefix(trimmed, "cat > /etc/sudoers.d/"):
 		return s.handleSudoersWrite(trimmed), 0
 	case strings.HasPrefix(trimmed, "visudo -cf /etc/sudoers.d/orca"):
-		if s.state["sudoers_valid"] == "true" {
-			return []byte("/etc/sudoers.d/orca: parsed OK\n"), 0
+		force := s.forceSudoersInvalid
+		if force || s.state["sudoers_valid"] != "true" {
+			return []byte("/etc/sudoers.d/orca: syntax error\n"), 1
 		}
-		return []byte("/etc/sudoers.d/orca: syntax error\n"), 1
+		return []byte("/etc/sudoers.d/orca: parsed OK\n"), 0
 	case strings.HasPrefix(trimmed, "cat /") && strings.HasSuffix(trimmed, "/authorized_keys"):
 		return s.readAuthFile(trimmed[4:]), 0
 	case strings.HasPrefix(trimmed, "cat /") && strings.Contains(trimmed, "/orca"):
@@ -406,6 +408,14 @@ func (d *staticDialer) DialContext(ctx context.Context, network, addr string, co
 	return d.client, nil
 }
 
+type funcDialer struct {
+	fn func(ctx context.Context, network, addr string, config *ssh.ClientConfig) (*ssh.Client, error)
+}
+
+func (d *funcDialer) DialContext(ctx context.Context, network, addr string, config *ssh.ClientConfig) (*ssh.Client, error) {
+	return d.fn(ctx, network, addr, config)
+}
+
 func TestBootstrapProxmox_FullFlow_Success(t *testing.T) {
 	srv := newFakeSSHServer(t)
 	defer srv.close()