Your default model changed under you, and three tools added switches to stop it

Cline 4.1.21 refreshed its catalog to 6,386 models across 209 providers and changed the default for 19 providers that don't pin one. Eleven of those moved to Claude Opus 5.5, including GitHub Copilot and Vertex. If you use Cline against one of those providers without an explicit model setting, your cost per task changed and you didn't edit anything.

A day later, Claude Code 2.1.283 added an availableModelsMatch "exact" managed setting. With exact matching, an availableModels entry permits only the version it names, so a new model release stays blocked until an admin adds it. The same release added deniedModels for outright blocks. GitHub, separately, gave Copilot admins until October 22 to choose a default model for future features, after which unconfigured orgs get whatever GitHub picks.

Three independent changelogs inside 48 hours, all pointing the same direction: model identity is becoming configuration you have to manage, not an implementation detail your tool handles.

For anyone running unattended pipelines, this is a reproducibility problem before it's a cost problem. A benchmark you ran in August against "the default model" isn't comparable to the same run today. A prompt tuned for one model's quirks will behave differently against another. And the cost delta between provider defaults is large enough to notice on a monthly bill.

2.1.283 has two other behavior changes that matter more than their changelog lines suggest. Interactive sessions on third-party providers, or with telemetry disabled, now start in auto mode when no permission mode is configured. If you relied on the old default of prompting before tool calls, pin permissions.defaultMode in managed settings before you update. And managed sandbox settings used to be ignored entirely when one nested value was invalid; now that single value fails closed and the rest of the block still applies. The old behavior meant a typo silently disabled your whole sandbox config.

The same release also fixed a Windows PowerShell hole where cmd /c rd, rmdir, del and erase could delete drive roots and the home folder, because the guard covered the Remove-Item cmdlet but not the cmd.exe built-ins.

Pin your models. Pin your permission mode. Both are one-line edits and both silently changed this week.