diff --git a/snapshots/anthropic/api-release-notes.md b/snapshots/anthropic/api-release-notes.md
index 958526c..fc9ba8e 100644
--- a/snapshots/anthropic/api-release-notes.md
+++ b/snapshots/anthropic/api-release-notes.md
@@ -5,4 +5,28 @@ For release notes on Claude Apps, see the Release notes for Claude Apps in the C
 For updates to Claude Code, see the complete CHANGELOG.md in the `claude-code` repository.
 
+### May 29, 2026
+
+- Claude Managed Agents webhooks, multiagent orchestration, and self-hosted sandboxes are now available on Claude Platform on AWS. See IAM actions for Claude Platform on AWS for the new IAM actions and the `AnthropicSelfHostedEnvironmentAccess` managed policy.
+
+### May 28, 2026
+
+- We've launched Claude Opus 4.8 (claude-opus-4-8), our most capable generally available model. Claude Opus 4.8 supports a 1M token context window by default, 128k max output tokens, and the same set of tools and platform features as Claude Opus 4.7. See What's new in Claude Opus 4.8 for capability improvements, new features, and migration guidance.
+- We've launched mid-conversation system messages. On Claude Opus 4.8, you can send `role: "system"` messages at non-first positions in the `messages` array, preserving prompt cache hits when instructions change during a long-running session. No beta header is required.
+- The Messages API now returns refusal categories in `stop_details` when Claude Opus 4.8 declines a request, so your application can route different classes of refusal to the right next step. No beta header is required. See Refusal categories.
+- On Claude Opus 4.8, the effort parameter defaults to `high` across all surfaces, including Claude Code and the Messages API.
+- On Claude Opus 4.8, the minimum cacheable prompt length for prompt caching is 1,024 tokens, lower than on Claude Opus 4.7.
+- Claude Opus 4.8 uses adaptive thinking to trigger reasoning only when a turn needs it, reducing wasted thinking tokens compared to Claude Opus 4.7 at the same effort level.
+- Claude Opus 4.8 supports high-resolution image input (up to 2576 pixels on the long edge), same as Claude Opus 4.7.
+- Task budgets now support Claude Opus 4.8.
+- The advisor tool now supports Claude Opus 4.8.
+- Computer use now supports Claude Opus 4.8.
+- Fast mode for Claude Opus 4.8 is available as a research preview on the Claude API only.
+- Setting the sampling parameters `temperature`, `top_p`, or `top_k` to a non-default value returns a 400 error on Claude Opus 4.8, same as on Claude Opus 4.7. See the migration guide for details.
+- In Claude Code, we've expanded Auto mode to more users for long-running tasks. See the Claude Code documentation.
+- In Claude Code, Max plan users now default to fast mode on Claude Opus 4.8. See the Claude Code documentation.
+- In Claude Code, Workflows are available as a research preview, letting you define and run multi-step agentic plans. See the Claude Code documentation.
+- We've deprecated fast mode for Claude Opus 4.6, with removal approximately 30 days after launch. Migrate to fast mode for Claude Opus 4.8 or Claude Opus 4.7. Read more in Fast mode.
+- For updates to claude.ai, Cowork, Claude for Microsoft 365, and other Claude apps in this release, see the release notes for Claude Apps.
+
 ### May 19, 2026