diff --git a/.gitignore b/.gitignore
index e7b87831..fbe3f796 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,3 +18,6 @@ buildNumber.properties
 
 # VS Code
 .vscode/
+
+# Copilot modernization session artifacts
+.github/modernize/
diff --git a/RELEASE-NOTES.md b/RELEASE-NOTES.md
new file mode 100644
index 00000000..25e135f3
--- /dev/null
+++ b/RELEASE-NOTES.md
@@ -0,0 +1,123 @@
+# d1_libclient_java Release Notes
+
+## 2.4.0 (2026-07-06)
+
+- Intent: Deliver a modernization and maintenance release aligned with current Java runtimes and the current d1_common_java line.
+- Security fixes: Updated Bouncy Castle dependencies to patch known security issues and hardened supporting behavior in related client paths.
+- New features: Java 17/21/25 compatibility updates, migration of deploy/build flow to maven.dataone.org and wagon-ssh, and CI coverage with Maven verify on pushes and pull requests.
+- Bug fixes: Refactored deprecated IOUtils usage, removed unused or extraneous dependencies/plugins/resources, adapted to d1_common API/library changes, and tightened runtime error handling in tests and client integration paths.
+- Dependency and tooling updates: Bumped d1_common_java dependency through 2.5.0 and refreshed project/build metadata for current release practices.
+
+## 2.3.1 (2018-02-09)
+
+- Intent: Provide a focused patch release for trust-store updates and NodeList retrieval robustness.
+- New features: Added LE and IdenTrust root certificates and refined fallback behavior when CN NodeList retrieval fails.
+- Bug fixes: Improved D1Client error messaging and reduced complexity in node location/selection paths used by v1 and v2 implementations.
+
+## 2.3.0 (2016-11-08)
+
+- Intent: Strengthen HTTP client behavior and align exception handling with the 2.3 generation of shared APIs.
+- New features: Added client-side HTTP caching, improved keep-alive/connection monitoring controls, and introduced utility classes for safer stream/HTTP-client lifecycle management.
+- Bug fixes: Replaced legacy JiBXException usage with MarshallingException, fixed latent NPE/class-cast edge cases in download and resolve flows, and removed outdated caching/dependency pieces.
+
+## 2.2.0 (2016-06-14)
+
+- Intent: Advance 2.2 compatibility and tighten client concurrency/transport defaults.
+- New features: Expanded connection-pool and timeout controls and improved monitor-thread behavior for HTTP connection management.
+- Bug fixes: Addressed thread-safety issues in request/header handling and synchronized client behavior with evolving DataONE endpoint expectations.
+
+## 2.1.1 (2016-03-15)
+
+- Intent: Deliver an incremental stabilization patch on top of 2.1.0.
+- New features: Point-release packaging and branch alignment updates.
+- Bug fixes: Minor release-engineering and integration adjustments to keep the 2.1 stream stable.
+
+## 2.1.0 (2016-02-24)
+
+- Intent: Evolve client authorization and v2 API ergonomics for broader DataONE usage.
+- New features: Added AuthTokenSession support and related token-aware REST client path selection for multipart operations.
+- Bug fixes: Tightened method signatures/exception behavior (including hasReservation and getCN(session) deprecations) and improved node-locator refresh and endpoint fallback logic.
+
+## 2.0.0 (2015-11-24)
+
+- Intent: Establish the 2.x line of the Java client library.
+- New features: Added broader v2 service support for package and object retrieval/use cases and refreshed test/build composition for the major release line.
+- Bug fixes: Corrected endpoint selection and fallback behavior in get/download paths and fixed stream/resource cleanup issues in multipart client operations.
+
+## 1.3.1 (2014-11-26)
+
+- Intent: Publish a patch-level follow-up to the 1.3.0 line.
+- New features: Version/packaging alignment with companion DataONE components.
+- Bug fixes: Dependency and release-preparation cleanup.
+
+## 1.3.0 (2014-05-02)
+
+- Intent: Open the 1.3 release branch and stabilize client behavior for the next cycle.
+- New features: Consolidated 1.3 branch baseline and compatibility updates.
+- Bug fixes: General release hardening and branch synchronization.
+
+## 1.2.5 (2013-08-08)
+
+- Intent: Provide a focused parsing refinement release.
+- New features: Refined ResourceMapFactory parsing to support serialized maps where only one side of inverse cito relationships is present.
+- Bug fixes: Improved resilience of ResourceMap ingestion for partially expressed relationship graphs.
+
+## 1.2.4 (2013-07-01)
+
+- Intent: Prepare the client library for the CCI-1.2 release train.
+- New features: Release alignment with coordinated DataONE component versions.
+- Bug fixes: Branch/version stabilization and release packaging updates.
+
+## 1.2.3 (2013-06-05)
+
+- Intent: Keep dependency behavior in sync with updated d1_common_java scope constraints.
+- New features: Updated dependency targeting to match new scope decisions in shared libraries.
+- Bug fixes: Reduced unnecessary transitive dependency exposure.
+
+## 1.2.2 (2013-06-04)
+
+- Intent: Improve distribution ergonomics for downstream consumers.
+- New features: Added jar-with-dependencies Maven assembly configuration.
+- Bug fixes: Build/distribution configuration cleanup for packaged client delivery.
+
+## 1.2.1 (2013-02-22)
+
+- Intent: Pull in the d1_common_java 1.1.1 compatibility/temp-file fix line.
+- New features: Updated shared dependency baseline.
+- Bug fixes: Indirectly resolves temp-file portability behavior through dependency alignment.
+
+## 1.2.0 (2013-02-12)
+
+- Intent: Establish the 1.2 release line.
+- New features: 1.2 baseline packaging and API alignment with companion components.
+- Bug fixes: Release consistency improvements and branch stabilization.
+
+## 1.1.0 (2013-01-08)
+
+- Intent: Deliver the first 1.1 generation of the client library.
+- New features: 1.1 baseline updates and coordinated dependency progression.
+- Bug fixes: General maintenance and release preparation changes.
+
+## 1.0.4 (2012-07-11)
+
+- Intent: Continue 1.0 patch-line hardening.
+- New features: Patch-level packaging and compatibility updates.
+- Bug fixes: Minor maintenance and release corrections.
+
+## 1.0.3 (2012-07-03)
+
+- Intent: Publish a maintenance patch after 1.0.2.
+- New features: Incremental release alignment with service/API revisions.
+- Bug fixes: Stabilization fixes and release engineering updates.
+
+## 1.0.2 (2012-06-19)
+
+- Intent: Add ORE-generation improvements in the 1.0 maintenance line.
+- New features: Incorporated ORE generation behavior using a #aggregation URI.
+- Bug fixes: Minor patch-level corrections accompanying the ORE update.
+
+## 1.0.1 (2012-06-05)
+
+- Intent: First general-availability release of d1_libclient_java after release candidates.
+- New features: Consolidated RC-era client utilities, multipart behaviors, and service-call wiring into the first stable 1.0 release.
+- Bug fixes: Included RC-stage fixes for stream handling, object format/cache behavior, and endpoint compatibility.
diff --git a/pom.xml b/pom.xml
index 87123d4d..808c0c66 100644
--- a/pom.xml
+++ b/pom.xml
@@ -5,14 +5,14 @@
   <groupId>org.dataone</groupId>
   <artifactId>d1_libclient_java</artifactId>
   <packaging>jar</packaging>
-  <version>2.4.0-SNAPSHOT</version>
+  <version>2.4.0</version>
   <name>DataONE Java Client Library</name>
   <url>http://dataone.org</url>
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <bouncycastle.version>1.84</bouncycastle.version>
-    <d1_common_java.version>2.5.0-SNAPSHOT</d1_common_java.version>
-    <d1_test_resources.version>2.4.0-SNAPSHOT</d1_test_resources.version>
+    <d1_common_java.version>2.5.0</d1_common_java.version>
+    <d1_test_resources.version>2.4.0</d1_test_resources.version>
     <maven.compiler.release>25</maven.compiler.release>
   </properties>
   <repositories>