Core Lightning v26.06 introduces several new features and improvements for both users and developers. Key updates include the 'graceful' command for smoother shutdowns, the 'sendamount' command for specifying payment amounts, and enhancements to the 'xpay' command which now replaces 'pay' for invoice payments. Developers benefit from new JSON-RPC commands like 'createproof' for BOLT12 payments and support for the 'lnp' payer proof format. Protocol updates include a longer wait time before closing channels and improved channel update handling.