diff --git a/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/DocumentKeywordExtractor.java b/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/DocumentKeywordExtractor.java
index b3b098cf..8feb5fd8 100644
--- a/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/DocumentKeywordExtractor.java
+++ b/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/DocumentKeywordExtractor.java
@@ -89,7 +89,11 @@ public class DocumentKeywordExtractor {
             var word = rep.word;
 
             if (!word.isBlank()) {
-                wordsBuilder.add(word, metadata.getMetadataForWord(rep.stemmed));
+                long meta = metadata.getMetadataForWord(rep.stemmed);
+
+                assert meta != 0L : "Missing meta for " + rep.word;
+
+                wordsBuilder.add(word, meta);
             }
         }
     }
@@ -112,14 +116,20 @@ public class DocumentKeywordExtractor {
 
                 String w = word.wordLowerCase();
                 if (matchesWordPattern(w)) {
-                    wordsBuilder.add(w, metadata.getMetadataForWord(word.stemmed()));
+                    long meta = metadata.getMetadataForWord(word.stemmed());
+                    assert meta != 0L : "Missing meta for " + word.word();
+
+                    wordsBuilder.add(w, meta);
                 }
             }
 
             for (var names : keywordExtractor.getProperNames(sent)) {
                 var rep = new WordRep(sent, names);
 
-                wordsBuilder.add(rep.word, metadata.getMetadataForWord(rep.stemmed));
+                long meta = metadata.getMetadataForWord(rep.stemmed);
+                assert meta != 0L : "Missing meta for " + rep.word;
+
+                wordsBuilder.add(rep.word, meta);
             }
         }
     }
diff --git a/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/extractors/KeywordPositionBitmask.java b/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/extractors/KeywordPositionBitmask.java
index b9274730..5e91b12c 100644
--- a/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/extractors/KeywordPositionBitmask.java
+++ b/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/extractors/KeywordPositionBitmask.java
@@ -23,6 +23,10 @@ public class KeywordPositionBitmask {
                 positionMask.merge(word.stemmed(), posBit, this::bitwiseOr);
             }
 
+            for (var span : keywordExtractor.getKeywordsFromSentence(sent)) {
+                positionMask.merge(sent.constructStemmedWordFromSpan(span), posBit, this::bitwiseOr);
+            }
+
             for (var span : keywordExtractor.getProperNames(sent)) {
                 positionMask.merge(sent.constructStemmedWordFromSpan(span), posBit, this::bitwiseOr);
             }
@@ -38,6 +42,10 @@ public class KeywordPositionBitmask {
                 positionMask.merge(word.stemmed(), posBit, this::bitwiseOr);
             }
 
+            for (var span : keywordExtractor.getKeywordsFromSentence(sent)) {
+                positionMask.merge(sent.constructStemmedWordFromSpan(span), posBit, this::bitwiseOr);
+            }
+
             for (var span : keywordExtractor.getProperNames(sent)) {
                 positionMask.merge(sent.constructStemmedWordFromSpan(span), posBit, this::bitwiseOr);
             }
diff --git a/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/extractors/WordsTfIdfCounts.java b/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/extractors/WordsTfIdfCounts.java
index 64f50dde..559f69a6 100644
--- a/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/extractors/WordsTfIdfCounts.java
+++ b/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/extractors/WordsTfIdfCounts.java
@@ -51,7 +51,7 @@ public class WordsTfIdfCounts implements WordReps, Comparator<WordRep> {
         for (var sent : dld.sentences) {
             var keywords = keywordExtractor.getKeywordsFromSentence(sent);
             for (var span : keywords) {
-                if (highTfIdfInstances.contains(spanToStemmed(sent, span))) {
+                if (highTfIdfInstances.contains(sent.constructStemmedWordFromSpan(span))) {
                     tfIdfHigh.add(new WordRep(sent, span));
                 }
             }
@@ -66,7 +66,7 @@ public class WordsTfIdfCounts implements WordReps, Comparator<WordRep> {
         for (var sent : dld.sentences) {
             var keywords = keywordExtractor.getKeywordsFromSentence(sent);
             for (var span : keywords) {
-                counts.addTo(spanToStemmed(sent, span), 1);
+                counts.addTo(sent.constructStemmedWordFromSpan(span), 1);
             }
         }
 
@@ -77,20 +77,6 @@ public class WordsTfIdfCounts implements WordReps, Comparator<WordRep> {
         return dict.getTermFreqStemmed(rep.stemmed);
     }
 
-    private String spanToStemmed(DocumentSentence sentence, WordSpan span) {
-        if (span.size() == 1)
-            return sentence.stemmedWords[span.start];
-
-        StringBuilder builder = new StringBuilder();
-        for (int i = span.start; i < span.end; i++) {
-            if (!builder.isEmpty())
-                builder.append('_');
-            builder.append(sentence.stemmedWords[i]);
-        }
-        return builder.toString();
-
-    }
-
     public int getTfIdf(String stemmed) {
         return tfIdf.getOrDefault(stemmed, 0);
     }
diff --git a/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/model/DocumentKeywords.java b/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/model/DocumentKeywords.java
index d22e0240..f8ad86d7 100644
--- a/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/model/DocumentKeywords.java
+++ b/code/features-convert/keyword-extraction/src/main/java/nu/marginalia/keyword/model/DocumentKeywords.java
@@ -1,10 +1,5 @@
 package nu.marginalia.keyword.model;
 
-
-import lombok.AllArgsConstructor;
-import lombok.Getter;
-import lombok.NoArgsConstructor;
-import lombok.Setter;
 import nu.marginalia.model.idx.WordMetadata;
 
 import java.io.Serial;
@@ -23,6 +18,16 @@ public final class DocumentKeywords implements Serializable {
     {
         this.keywords = keywords;
         this.metadata = metadata;
+
+        assert keywords.length == metadata.length;
+
+        if (DocumentKeywords.class.desiredAssertionStatus()) {
+            for (int i = 0; i < metadata.length; i++) {
+                if (metadata[i] == 0) {
+                    System.err.println("Bad metadata for keyword " + keywords[i]);
+                }
+            }
+        }
     }
 
     @Override
diff --git a/code/tools/experiment-runner/build.gradle b/code/tools/experiment-runner/build.gradle
index 3552326a..77d84e21 100644
--- a/code/tools/experiment-runner/build.gradle
+++ b/code/tools/experiment-runner/build.gradle
@@ -36,6 +36,7 @@ dependencies {
 
     implementation project(':code:features-convert:adblock')
     implementation project(':code:features-convert:topic-detection')
+    implementation project(':code:features-convert:keyword-extraction')
 
     implementation libs.lombok
     annotationProcessor libs.lombok
diff --git a/code/tools/experiment-runner/src/main/java/nu/marginalia/tools/experiments/SentenceStatisticsExperiment.java b/code/tools/experiment-runner/src/main/java/nu/marginalia/tools/experiments/SentenceStatisticsExperiment.java
index 44f3cf18..554ba4fe 100644
--- a/code/tools/experiment-runner/src/main/java/nu/marginalia/tools/experiments/SentenceStatisticsExperiment.java
+++ b/code/tools/experiment-runner/src/main/java/nu/marginalia/tools/experiments/SentenceStatisticsExperiment.java
@@ -1,10 +1,14 @@
 package nu.marginalia.tools.experiments;
 
 import com.google.inject.Inject;
+import lombok.SneakyThrows;
 import nu.marginalia.WmsaHome;
 import nu.marginalia.converting.processor.logic.dom.DomPruningFilter;
 import nu.marginalia.crawling.model.CrawledDomain;
+import nu.marginalia.keyword.DocumentKeywordExtractor;
 import nu.marginalia.language.sentence.SentenceExtractor;
+import nu.marginalia.model.EdgeUrl;
+import nu.marginalia.term_frequency_dict.TermFrequencyDict;
 import nu.marginalia.tools.Experiment;
 import org.jsoup.Jsoup;
 
@@ -18,6 +22,7 @@ import java.nio.file.Path;
 public class SentenceStatisticsExperiment extends Experiment {
 
     SentenceExtractor se = new SentenceExtractor(WmsaHome.getLanguageModels());
+    DocumentKeywordExtractor documentKeywordExtractor = new DocumentKeywordExtractor(new TermFrequencyDict(WmsaHome.getLanguageModels()));
     Path filename;
     PrintWriter writer;
 
@@ -32,6 +37,7 @@ public class SentenceStatisticsExperiment extends Experiment {
     private void logLine(String message) {
         System.out.printf("\u001b[2K\r%s", message);
     }
+    @SneakyThrows
     @Override
     public boolean process(CrawledDomain domain) {
         if (domain.doc == null) return true;
@@ -46,17 +52,9 @@ public class SentenceStatisticsExperiment extends Experiment {
             parsed.body().filter(new DomPruningFilter(0.5));
 
             var dld = se.extractSentences(parsed);
+            var keywords = documentKeywordExtractor.extractKeywords(dld, new EdgeUrl(doc.url));
 
-
-            int numSentences = dld.sentences.length;
-            if (numSentences == 0) {
-                continue;
-            }
-
-            double avgLength = dld.totalNumWords() / (double) numSentences;
-            if (avgLength < 5 && dld.totalNumWords() > 250) {
-                writer.printf("%s\t%d\t%f\n", doc.url, dld.totalNumWords(), avgLength);
-            }
+            keywords.build();
         }
 
         return true;
diff --git a/run/experiment.sh b/run/experiment.sh
index 4343c0e0..f8651bf5 100755
--- a/run/experiment.sh
+++ b/run/experiment.sh
@@ -14,6 +14,7 @@ echo "args = $ARGS"
 JAVA_OPTS="
 -Dcrawl.rootDirRewrite=/crawl:${SAMPLE_DIR}
 -Ddb.overrideJdbc=jdbc:mariadb://localhost:3306/WMSA_prod?rewriteBatchedStatements=true
+-ea
 "
 
 ## Configuration ends