{"version":"2.1.67","anchor":"automatic-sonnet-4-5-sonnet-4-6-migration","canonical_anchor":"automatic-sonnet-4-5-sonnet-4-6-migration","heading":"Automatic Sonnet 4.5 \u2192 Sonnet 4.6 Migration","tier":null,"area":null,"scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.67\/e\/automatic-sonnet-4-5-sonnet-4-6-migration","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.67","markdown":"### Automatic Sonnet 4.5 \u2192 Sonnet 4.6 Migration\n\n**What**\n\nUsers whose model setting references `claude-sonnet-4-5-20250929` (or its `[1m]` extended-thinking variant) are automatically migrated to `sonnet` (or `sonnet[1m]`). A notification \"Model updated to Sonnet 4.6\" is shown briefly after the migration.\n\n**Details**\n\n- Applies only to first-party (claude.ai-authenticated) users on Pro, Max, or Team plans\n- Extended thinking mode (`[1m]`) is preserved during migration\n- Users who have already started at least one session will see the notification; brand-new users will not\n\n**Evidence**\n\nSonnet 4.5 to 4.6 migration (search for `\"tengu_sonnet45_to_46_migration\"` and `\"Model updated to Sonnet 4.6\"`)"}