Claude Managed Agents: event deltas, backward pagination, session overrides, credential injection location, and expanded webhooks

Claude Managed Agents session event streams now support event deltas. Opt in with the event_deltas[] query parameter on GET /v1/sessions/{session_id}/events/stream. Listing sessions now supports backward pagination with prev_page cursor. When creating a session, you can now override the agent's configuration for that session by passing agent with type: "agent_with_overrides" to replace the model, system prompt, tools, MCP servers, or skills. Vaults now support an injection_location setting on environment variable credentials, controlling whether the credential's value is substituted into request headers, request body, or both. Webhooks now cover agent, deployment, and deployment run lifecycle events.