feat: support claude agent SDK-style structured outputs in the OpenCode SDK (#8161)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Co-authored-by: Dax Raad <d@ironbay.co>

packages/opencode/src/session/llm.ts

@@ -38,6 +38,7 @@ export namespace LLM {
     small?: boolean
     tools: Record<string, Tool>
     retries?: number
+    toolChoice?: "auto" | "required" | "none"
   }
 
   export type StreamOutput = StreamTextResult<ToolSet, unknown>
@@ -205,6 +206,7 @@ export namespace LLM {
       providerOptions: ProviderTransform.providerOptions(input.model, params.options),
       activeTools: Object.keys(tools).filter((x) => x !== "invalid"),
       tools,
+      toolChoice: input.toolChoice,
       maxOutputTokens,
       abortSignal: input.abort,
       headers: {