diff --git a/workspace-server/internal/handlers/registry.go b/workspace-server/internal/handlers/registry.go
index 299436d31..f17603cb7 100644
--- a/workspace-server/internal/handlers/registry.go
+++ b/workspace-server/internal/handlers/registry.go
@@ -309,6 +309,8 @@ func validateAgentURL(rawURL string) error {
 // (covers prod `*.moleculesai.app` and staging `*.staging.moleculesai.app`) and
 // is overridable via MOLECULE_APP_DOMAIN for other deployments.
 func isPlatformTunnelHostname(h string) bool {
+	// DNS is case-insensitive and FQDN-form hostnames may carry a trailing dot.
+	h = strings.ToLower(strings.TrimSuffix(h, "."))
 	if !strings.HasPrefix(h, "ws-") {
 		return false
 	}
@@ -316,6 +318,7 @@ func isPlatformTunnelHostname(h string) bool {
 	if domain == "" {
 		domain = "moleculesai.app"
 	}
+	domain = strings.ToLower(strings.TrimSuffix(domain, "."))
 	return strings.HasSuffix(h, "."+domain)
 }
 
diff --git a/workspace-server/internal/handlers/registry_test.go b/workspace-server/internal/handlers/registry_test.go
index 44d7a0127..949b70147 100644
--- a/workspace-server/internal/handlers/registry_test.go
+++ b/workspace-server/internal/handlers/registry_test.go
@@ -895,9 +895,13 @@ func TestValidateAgentURL_PendingPlatformTunnel(t *testing.T) {
 	}{
 		{"ws-abc123.moleculesai.app", true},
 		{"ws-abc123.staging.moleculesai.app", true},
-		{"ws-abc123.evil.com", false},       // not under the platform domain
-		{"api.moleculesai.app", false},      // no ws- prefix
-		{"ws-x.fakemoleculesai.app", false}, // lookalike domain, not a subdomain
+		{"WS-ABC123.MOLECULESAI.APP", true},          // case-insensitive DNS
+		{"ws-abc123.moleculesai.app.", true},         // FQDN trailing dot
+		{"WS-ABC123.STAGING.MOLECULESAI.APP.", true}, // both case + trailing dot
+		{"ws-abc123.evil.com", false},                // not under the platform domain
+		{"api.moleculesai.app", false},               // no ws- prefix
+		{"ws-x.fakemoleculesai.app", false},          // lookalike domain, not a subdomain
+		{"ws-abc123moleculesai.app", false},          // missing dot before platform domain
 	} {
 		if got := isPlatformTunnelHostname(tc.h); got != tc.want {
 			t.Errorf("isPlatformTunnelHostname(%q)=%v want %v", tc.h, got, tc.want)