Automatic Sonnet 4.5 → Sonnet 4.6 Migration #
What
Users 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.
Details
- Applies only to first-party (claude.ai-authenticated) users on Pro, Max, or Team plans
- Extended thinking mode (
[1m]) is preserved during migration - Users who have already started at least one session will see the notification; brand-new users will not
Evidence
Sonnet 4.5 to 4.6 migration (search for "tengu_sonnet45_to_46_migration" and "Model updated to Sonnet 4.6")
Automatic Legacy Opus Model String Migration #
What
Users configured with explicit old-format Opus model IDs (claude-opus-4-20250514, claude-opus-4-1-20250805, claude-opus-4-0, claude-opus-4-1) are automatically migrated to the canonical opus alias. A notification "Model updated to Opus 4.6" is shown briefly after the migration.
Details
- Applies to first-party users only
- A new allowlist (
fXz) defines the four legacy Opus model strings subject to migration - The previous Opus 4.5 → Pro migration notification ("Model updated to Opus 4.5") has been replaced by this updated path
Evidence
Legacy Opus migration (search for "tengu_legacy_opus_migration" and "legacyOpusMigrationTimestamp")
Opus 4.6 Medium Effort Default Extended to Max and Team Plans #
What
The automatic "medium" effort level default for Opus 4.6 previously applied only to Pro plan users. It now also applies to Max plan users and eligible Team plan users.
Details
- The previous condition checked only for
plan === "pro" (via Yb6()) - The new condition checks
LK6() || my() || By(), which covers Pro, Max, and qualifying Team plans - A new notification "Opus 4.6 effort updated to medium" is displayed when the effort migration occurs for existing users
Evidence
Expanded plan check in effort default — BX6() function (search for "opus-4-6" near "medium" and "Opus 4.6 effort updated to medium")
Effort Callout Suppressed for First-Time Users #
What
The effort level information callout for Opus 4.6 is now automatically dismissed on a user's very first session, avoiding unnecessary friction for new users.
Details
- When
numStartups <= 1, the callout is skipped and effortCalloutDismissed is set to true immediately - Existing users who have had multiple sessions will continue to see the callout as before (if not previously dismissed)
Evidence
First-startup guard in effort callout — ahq() function (search for "effortCalloutDismissed" near "numStartups")