Add device agent library

Provide enrollment, elevated install, posture checks, keystore, and
system-tray helpers shared by the probo-agent binary.

Signed-off-by: Ludovic Vielle <ludovic@probo.com>

pkg/deviceagent/tray/autostart_windows.go

@@ -0,0 +1,94 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+//go:build windows
+
+package tray
+
+import (
+	"errors"
+	"fmt"
+
+	"golang.org/x/sys/windows/registry"
+)
+
+const runKeyPath = `Software\Microsoft\Windows\CurrentVersion\Run`
+
+const runValueName = "ProboAgentTray"
+
+func RegisterAutoStart(exePath string, runDir string) error {
+	if exePath == "" {
+		return fmt.Errorf("executable path is required")
+	}
+	if runDir == "" {
+		return fmt.Errorf("enrollment run directory is required")
+	}
+
+	sid, err := currentInteractiveUserSID()
+	if err != nil {
+		return fmt.Errorf("cannot resolve interactive user for tray auto-start: %w", err)
+	}
+
+	keyPath := sid + `\` + runKeyPath
+
+	key, _, err := registry.CreateKey(registry.USERS, keyPath, registry.SET_VALUE)
+	if err != nil {
+		return fmt.Errorf("cannot open or create Run registry key for interactive user: %w", err)
+	}
+
+	defer func() { _ = key.Close() }()
+
+	command := fmt.Sprintf(`"%s" tray --run-dir "%s"`, exePath, runDir)
+	if err := key.SetStringValue(runValueName, command); err != nil {
+		return fmt.Errorf("cannot set Run registry value: %w", err)
+	}
+
+	return nil
+}
+
+func UnregisterAutoStart() error {
+	sid, err := currentInteractiveUserSID()
+	if err != nil {
+		return fmt.Errorf("cannot resolve interactive user for tray auto-start: %w", err)
+	}
+
+	keyPath := sid + `\` + runKeyPath
+
+	key, err := registry.OpenKey(registry.USERS, keyPath, registry.SET_VALUE)
+	if err != nil {
+		if errors.Is(err, registry.ErrNotExist) {
+			return nil
+		}
+
+		return fmt.Errorf("cannot open Run registry key for interactive user: %w", err)
+	}
+
+	defer func() { _ = key.Close() }()
+
+	if err := key.DeleteValue(runValueName); err != nil {
+		if errors.Is(err, registry.ErrNotExist) {
+			return nil
+		}
+
+		return fmt.Errorf("cannot delete Run registry value: %w", err)
+	}
+
+	return nil
+}