1 files changed, 35 insertions, 0 deletions
diff --git a/internal/session/spec.go b/internal/session/spec.go
index 2d1b77d..0a6ad4e 100644
--- a/internal/session/spec.go
+++ b/internal/session/spec.go
@@ -1,6 +1,8 @@
 package session
 
 import (
+	"encoding/base64"
+	"encoding/json"
 	"fmt"
 	"strings"
 
@@ -45,6 +47,30 @@ func (s Spec) Commands() ([]string, error) {
 	}
 }
 
+// StartCommand returns the SESSION START command for this specification.
+func (s Spec) StartCommand() (string, error) {
+	payload, err := s.encodedPayload()
+	if err != nil {
+		return "", err
+	}
+
+	return fmt.Sprintf("SESSION START %s", payload), nil
+}
+
+// UpdateCommand returns the SESSION UPDATE command for this specification.
+func (s Spec) UpdateCommand(generation uint64) (string, error) {
+	payload, err := s.encodedPayload()
+	if err != nil {
+		return "", err
+	}
+
+	if generation == 0 {
+		return fmt.Sprintf("SESSION UPDATE %s", payload), nil
+	}
+
+	return fmt.Sprintf("SESSION UPDATE %d %s", generation, payload), nil
+}
+
 func (s Spec) queryCommands() ([]string, error) {
 	if s.Mode != omode.MapClient && s.Mode != omode.TailClient {
 		return nil, fmt.Errorf("session spec query mode requires map or tail mode, got %s", s.Mode)
@@ -122,3 +148,12 @@ func splitFiles(what string) []string {
 	}
 	return files
 }
+
+func (s Spec) encodedPayload() (string, error) {
+	payload, err := json.Marshal(s)
+	if err != nil {
+		return "", fmt.Errorf("marshal session spec: %w", err)
+	}
+
+	return base64.StdEncoding.EncodeToString(payload), nil
+}