fix: extract tool arguments from response.completed in streaming

[dannote]

Description

OpenRouter Responses API doesn't stream tool arguments via response.function_call_arguments.delta events. The arguments field in response.function_call_arguments.done is empty, and the complete arguments are only available in the final response.completed event's output array.

This causes tool calls to fail with validation errors like:

Invalid input for tool weather: Type validation failed: Value: {}.
Error message: [{"expected":"string","code":"invalid_type","path":["location"],"message":"Required"}]

Changes

• Accumulate argument deltas during streaming (in case a provider does send them)
• Track emitted tool calls to avoid duplicates
• Extract tool call arguments from response.completed event's output array
• Only emit tool-input-* events when actual arguments are available

Checklist

• I have run pnpm stylecheck and pnpm typecheck
• I have run pnpm test and all tests pass
• I have added tests for my changes (if applicable)
• I have updated documentation (if applicable)

Changeset

• I have run pnpm changeset to create a changeset file

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/OpenRouterTeam/ai-sdk-provider/@openrouter/ai-sdk-provider@336

commit: fb49892

[robert-j-y]

Thank you for reporting this issue. This was filed against v6.0.0-alpha.* which was a pre-release version.

We've since released v2.0.0 with stable AI SDK v6 support. The alpha versions will be deprecated.

Please try upgrading to @openrouter/ai-sdk-provider@latest (v2.0.0+) and let us know if you still experience this issue.

Release reference: https://github.com/OpenRouterTeam/ai-sdk-provider/releases