Source Intelligence

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

All of v2.1.174 Home All releases olderv2.1.173 v2.1.175newer
Claude Code v2.1.174

Fallback Model Event Covers More Trigger Types

The internal model_switched event — emitted when a turn falls back from the primary model — now tracks two additional trigger reasons: "server_error" (retryable 5xx pivot) and "last_resort" (non-retryable error on the primary). Previously only model_not_found, permission_denied, and overloaded were tracked.

Evidence

Fallback trigger enum (search for "last_resort" near "model_not_found" and "overloaded" in the fallback model schema)

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.174 →