diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 6987fe52f..d433cd0b5 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,4 +1,4 @@
 {
-  ".": "9.6.2",
+  ".": "10.0.0",
   "packages/adcp-reporting-storage": "0.1.0-beta.5"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0144841f5..76d9bc884 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -192,6 +192,17 @@
   change public consumer defaults. See
   [format-kind migration](docs/canonical-format-kinds-migration.md).
 
+## [10.0.0](https://github.com/adcontextprotocol/adcp-client-python/compare/v9.6.2...v10.0.0) (2026-11-13)
+
+
+### ⚠ BREAKING CHANGES
+
+* **webhooks:** Webhook challenge helpers now require seller_agent_url and event_types, and proof challenges require an RFC 9421 WebhookSender; pass legacy delivery authentication alongside that sender.
+
+### Bug Fixes
+
+* **webhooks:** comply with challenge schema ([bedea16](https://github.com/adcontextprotocol/adcp-client-python/commit/bedea168d9c467cab5ca8fff13ea013d4df573cf))
+
 ## [9.6.2](https://github.com/adcontextprotocol/adcp-client-python/compare/v9.6.1...v9.6.2) (2026-11-09)
 
 
diff --git a/pyproject.toml b/pyproject.toml
index 4a6786ef8..d57df83c4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "adcp"
-version = "9.6.2"
+version = "10.0.0"
 description = "Official Python client for the Ad Context Protocol (AdCP)"
 authors = [
     {name = "AdCP Community", email = "maintainers@adcontextprotocol.org"}