Hidden flags to start on models Claude Code does not recognise

What

This release adds two hidden command-line flags. A flag is an option you type after claude when you start it. Both flags are about running Claude Code on a model it would normally refuse.

• --include-unsupported-models offers models your account can use that this version of Claude Code does not know. Its value is stored as includeUnsupportedModels and is off unless you pass the flag. The check that decides whether a model is valid reads it. No setting or other way to turn it on was found.
• --allow-other-models, or the environment variable CLAUDE_CODE_ALLOW_OTHER_MODELS=1, is for sessions started with --client-data-url (or CLAUDE_CODE_CLIENT_DATA_URL). These point Claude Code at a signed document that holds per-model client data. An environment variable is a named value set in your shell before you start a program.
• With --client-data-url, startup now exits with an error when the document has no entry for the selected model. Before, Claude Code only reported that the document was "loaded, not applied" and carried on.
• The new error tells you to pass a matching --model, or --allow-other-models (CLAUDE_CODE_ALLOW_OTHER_MODELS=1), to start without applying the document. With the flag, the session starts on that model and applies none of the document's per-model client data.
• Both flags are carried along when Claude Code relaunches itself and when it starts other processes. allowOtherModels is mapped to CLAUDE_CODE_ALLOW_OTHER_MODELS for this.

Why

If you use --client-data-url, a document that does not cover your model now stops startup instead of being quietly skipped. Pass --model to pick a model the document covers, or use --allow-other-models to start anyway. --include-unsupported-models gets past the usual model check, so it can offer models this version of Claude Code does not know about.