(index) Tune ranking for verbatim matches in the title, rewarding shorter titles

code/index/index-forward/java/nu/marginalia/index/forward/spans/DocumentSpan.java

@@ -71,6 +71,22 @@ public class DocumentSpan {
         return startsEnds.iterator();
     }
 
+    public int length() {
+        if (null == startsEnds) {
+            return 0;
+        }
+
+        int len = 0;
+        var iter = startsEnds.iterator();
+
+        while (iter.hasNext()) {
+            len -= iter.nextInt();
+            len += iter.nextInt();
+        }
+
+        return len;
+    }
+
     public int size() {
         return startsEnds.valueCount() / 2;
     }

code/index/java/nu/marginalia/index/results/IndexResultScoreCalculator.java

@@ -197,13 +197,18 @@ public class IndexResultScoreCalculator {
             temporalBias = 0;
         }
 
+        final int titleLength = spans.title.length();
+
         float coherenceScore = 0.f;
 
         // Calculate a bonus for keyword coherences when large ones exist
         int largestOptional = coherences.largestOptional();
         if (largestOptional >= 2) {
             if (largestOptional == coherences.testOptional(positions, spans.title)) {
-                coherenceScore = 2.0f * largestOptional;
+                // verbatim title match
+                coherenceScore = 4.0f * largestOptional;
+                // additional bonus if the match is most of the title's length
+                coherenceScore += 2.f * largestOptional / titleLength;
             }
             else if (largestOptional == coherences.testOptional(positions, spans.heading)) {
                 coherenceScore = 1.5f * largestOptional;