ToolCall.Name and .Arguments are json:"-" (runtime-only), so after chat
history round-trips through the session store only ToolCall.Function
survives. The anthropic-messages and anthropic (SDK) providers emitted
tool_use blocks from tc.Name alone, silently skipping every historical
tool call while still emitting the matching tool_result — orphaned
tool_results 400 at the API ("unexpected tool_use_id found in
tool_result blocks"), killing every turn on agents with tool history.
Fall back to Function.Name / json-parsed Function.Arguments (the same
pattern the bedrock and openai_compat providers already use), and cover
the deserialized-history shape with table tests in both providers.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
AayushGupta16
994c0aea11