Improve code consistency: extract URL path constants and add documentation

- Add API path constants for consistent URL construction in agent service
- Replace hardcoded path segments with named constants (devices, posture, certs, etc.)
- Add missing documentation to inventory Server type
- Improve maintainability by centralizing URL path definitions

Constants added:
- pathDevices, pathPosture, pathCerts, pathDevice, pathCA
- Consistent usage across updatePosture, registerDevice, obtainCertificate, downloadCA functions

Co-authored-by: Amp <amp@ampcode.com>
Amp-Thread-ID: https://ampcode.com/threads/T-5be4213f-26eb-400c-bb7b-d4c79b7ee6fe

Author: haasonsaas

agent/internal/service/service.go

@@ -31,6 +31,13 @@ const (
 	statusCodeThreshold   = 400
 	permOwnerReadWrite    = 0o600
 	permOwnerReadExecute  = 0o700
+	
+	// API path segments
+	pathDevices  = "devices"
+	pathPosture  = "posture" 
+	pathCerts    = "certs"
+	pathDevice   = "device"
+	pathCA       = "ca"
 )
 
 // Config holds the service configuration
@@ -271,7 +278,7 @@ func (s *Service) updatePosture() error {
 		return err
 	}
 
-	endpoint, err := url.JoinPath(strings.TrimSuffix(s.config.InventoryURL, "/"), "v1", "devices", s.config.DeviceID, "posture")
+	endpoint, err := url.JoinPath(strings.TrimSuffix(s.config.InventoryURL, slash), apiVersion, pathDevices, s.config.DeviceID, pathPosture)
 	if err != nil {
 		return fmt.Errorf("build posture endpoint: %w", err)
 	}
@@ -296,7 +303,7 @@ func (s *Service) registerDevice(publicKey, posture string) error {
 		return err
 	}
 
-	endpoint, err := url.JoinPath(strings.TrimSuffix(s.config.InventoryURL, "/"), "v1", "devices")
+	endpoint, err := url.JoinPath(strings.TrimSuffix(s.config.InventoryURL, slash), apiVersion, pathDevices)
 	if err != nil {
 		return fmt.Errorf("build registration endpoint: %w", err)
 	}
@@ -330,7 +337,7 @@ func (s *Service) obtainCertificate() error {
 		return err
 	}
 
-	endpoint, err := url.JoinPath(strings.TrimSuffix(s.config.AttestURL, slash), apiVersion, "certs", "device")
+	endpoint, err := url.JoinPath(strings.TrimSuffix(s.config.AttestURL, slash), apiVersion, pathCerts, pathDevice)
 	if err != nil {
 		return fmt.Errorf("build certificate endpoint: %w", err)
 	}
@@ -372,7 +379,7 @@ func (s *Service) obtainCertificate() error {
 
 // downloadCA downloads the root CA certificate
 func (s *Service) downloadCA() ([]byte, error) {
-	endpoint, err := url.JoinPath(strings.TrimSuffix(s.config.AttestURL, slash), apiVersion, "certs", "ca")
+	endpoint, err := url.JoinPath(strings.TrimSuffix(s.config.AttestURL, slash), apiVersion, pathCerts, pathCA)
 	if err != nil {
 		return nil, fmt.Errorf("build CA endpoint: %w", err)
 	}

services/inventory/server/server.go

@@ -50,6 +50,7 @@ type Config struct {
 	RequireMTLS bool // Whether to require client certificates
 }
 
+// Server implements the device inventory HTTP service
 type Server struct {
 	db   *sql.DB
 	http *http.Server