Implemented operations helper commands for validation, locking, and status

internal/artifacts/s3_keys.go

@@ -40,6 +40,12 @@ func S3SessionConfigKey(sessionPrefix string) string {
 	return path.Join(strings.TrimSuffix(cleanS3Key(sessionPrefix), "/"), "session.yml")
 }
 
+// S3SessionLocksKey returns the mutable session lock store key.
+// Format: {session_prefix}/locks.yml
+func S3SessionLocksKey(sessionPrefix string) string {
+	return path.Join(strings.TrimSuffix(cleanS3Key(sessionPrefix), "/"), "locks.yml")
+}
+
 // S3CurrentManifestKey returns the current manifest pointer key.
 // Format: {session_prefix}/current/manifest.json
 func S3CurrentManifestKey(sessionPrefix string) string {

internal/artifacts/s3_keys_test.go

@@ -22,6 +22,11 @@ func TestS3KeyConstruction(t *testing.T) {
 		t.Fatalf("session config key = %q", sessionConfigKey)
 	}
 
+	locksKey := S3SessionLocksKey(`dnd\campaigns\forsaken\sessions\2026-04-19\`)
+	if locksKey != "dnd/campaigns/forsaken/sessions/2026-04-19/locks.yml" {
+		t.Fatalf("locks key = %q", locksKey)
+	}
+
 	runPrefix := S3RunPrefix(sessionPrefix, runID)
 	wantRunPrefix := "dnd/campaigns/forsaken/sessions/2026-04-19/runs/" + runID + "/"
 	if runPrefix != wantRunPrefix {