Centralize link URL validation

internal/publish/links_test.go

@@ -1,6 +1,7 @@
 package publish
 
 import (
+	"strings"
 	"testing"
 
 	"gitea.maximumdirect.net/eric/distributor/internal/config"
@@ -147,3 +148,22 @@ func TestPlanLinksLeavesOutputsUnchangedWithoutConfig(t *testing.T) {
 		t.Fatalf("output URL = %q, want empty", linked[0].URL)
 	}
 }
+
+func TestPlanLinksValidatesBaseURLBeforePlanning(t *testing.T) {
+	_, _, err := PlanLinks(Request{
+		DestinationBundlePath: "daily",
+		Links: &config.Links{
+			BaseURL: "https://reports.example.com/archive?preview=1",
+			Primary: config.LinkPrimaryAuto,
+		},
+	}, []Output{{
+		DestinationPath: "report.md",
+		Kind:            state.OutputKindSource,
+	}})
+	if err == nil {
+		t.Fatal("PlanLinks() error = nil, want error")
+	}
+	if !strings.Contains(err.Error(), "link base URL: must not include a query string") {
+		t.Fatalf("PlanLinks() error = %q, want link base URL context", err)
+	}
+}