New unrecognized-model telemetry on /model switch

Switching to an unrecognized model now fires its own telemetry event.

Under the hood Internal Changes

JSON All of v2.1.260

Under the hoodTier: how much it should matter to you

1Useful: my rating, 1 to 5

1Signal: worth watching, 1 to 5

ModelsArea: what it touches

Internal ChangesKind: in v2.1.260, 03 Sep 26

Internal ChangesSection of the release

Attempting to switch to an unrecognized model string now fires the tengu_set_model_unrecognized telemetry event, recording the shape of the bad input and whether a suggestion was offered.

How sure we are

One source agreesOne thing we can check says the same as this entry.

Anthropic's release notes agreeFixed the /model picker not showing Fable 5.1 for organizations that can use it, which was only accepted when typed as /model…

See this entry in the whole of v2.1.260 →

The build it came inv2.1.260

3 Sep 2026 · 383 entries, this one is #286.

Use it now55
You'll notice151
Nothing to try yet34
Under the hood143

Either side of it

v2.1.259Older
v2.1.261Newer

Open the release →

Names in this entry

slash/model
Switch the AI model and save it as your default for new sessions. For models that support it, use left/right arrows to adjust effort level. With no argument, opens a picker; press s on a row to switch for the current session only. See when Claude Code asks you to confirm the switch. Once you confirm the switch, if Claude Code asks, Claude Code applies the change without waiting for the current response to finish. Before v2.1.242, Claude Code decided from a feature flag it fetched from Anthropic whether to run the command mid-turn or queue it until the turn finished, and always queued it in a session that doesn't fetch feature flags, such as on a third-party provider. Also available in non-interactive mode (-p) with a model argument instead of the picker, where it applies to the current session only and isn't saved as your default; requires Claude Code v2.1.205 or later
flagtengu_set_model_unrecognized
Switching to a model you aren't allowed to use now falls back to a substitute instead of failing.

Anthropic's note

Upstream's own release notes for v2.1.260 name something this entry names, so the two are probably about the same change. Probably: the pairing is made on a shared name rather than on the words around it.

Fixed the /model picker not showing Fable 5.1 for organizations that can use it, which was only accepted when typed as /model claude-fable-5-1

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