diff --git a/changelog.md b/changelog.md
index 517e9f7..9c1400b 100644
--- a/changelog.md
+++ b/changelog.md
@@ -15,3 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Word tokeniser with Unicode normalisation support
 - Configuration module with pydantic-settings
 - Structured logging with structlog
+- Metrics module with `Metric` protocol, `AggregateStats`, and `BatchResult` types
+- BLEU metric implementation (BLEU-1 through BLEU-4 with brevity penalty)
+- Lexical similarity metric (Jaccard similarity and token overlap)
+- Batch scoring with aggregate statistics for all metrics