{"version":"2.1.228","anchor":"assistant-messages-carry-two-new-null-fields","canonical_anchor":"assistant-messages-carry-two-new-null-fields","heading":"Assistant messages carry two new null fields","tier":"internal","area":"API Client","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.228\/e\/assistant-messages-carry-two-new-null-fields","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.228","markdown":"### Assistant messages carry two new null fields\n\nMessages Claude Code writes itself now include two empty fields to match the upgraded message format.\n\n**What**\n\nMessages Claude Code synthesizes itself, such as tool-use notices, stop-sequence messages and virtual transcript entries, now set `diagnostics: null` and a null token-details field in usage, matching the upgraded SDK message type.\n\n**Evidence**\n\n`diagnostics: null`\n\n- Area: API Client\n- Tier: Under the hood\n- Useful: 1\/5\n- Signal: 1\/5"}