Error with Gemini models

[korrectional]

I was using gemini 2.5 flash and got this error when I tried to do something with the browser.

Function call is missing a thought_signature in functionCall parts. This is required for tools to work correctly, and missing thought_signature may lead to degraded model performance. Additional data, function call default_api:addMcpServer , position 4. Please refer to https://ai.google.dev/gemini-api/docs/thought-signatures for more details.

[arkml]

@ramnique ^^

[ramnique]

Root cause found — this was fixed in 091f3e3.

Gemini 2.5 models attach an opaque thought_signature to each functionCall and require it to be echoed back verbatim on the next request of a tool turn. The turn runtime that shipped on Jul 2 (#655) dropped provider metadata when persisting tool-call parts from the model stream, so the follow-up request (history + tool result) replayed the functionCall without its signature and Gemini rejected it with the error above.

091f3e3 ("preserve block-level provider metadata in the turns bridge") closes exactly that gap — verified at the wire level that the outgoing functionCall part carries thoughtSignature again. The same channel also covers Anthropic thinking signatures and OpenAI encrypted reasoning.

Fix: the fix will reach you in an app update within the next couple of days — no action needed on your side. Please reopen if you still see this after updating.