diff --git a/CHANGELOG.md b/CHANGELOG.md
index 336cdfa0..b5cd119a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 # Changelog
 
+## Unreleased
+
+- Expanded CONTRIBUTING.md with detailed guidance on the issue creation process, label system,
+  ticket lifecycle, pull request requirements, and review/merge process.
+- Added commit scope, quality, and message format guidelines to CONTRIBUTING.md.
+- Migrated implementation timeline from the monolithic implementation plan to `docs/timeline.md`.
+- Migrated implementation notes to `docs/implementation-notes.md`.
+- Relocated remaining implementation plan content to the specification and CONTRIBUTING.md,
+  and removed `implementation_plan.md` from the repository.
+- Updated CONTRIBUTING.md to include project-specific conventions for tooling, testing,
+  type checking, and code style.
+
 ## v1.0.0
 
 First release.