feat: add extract reasoning middleware (#6463)

packages/opencode/src/session/llm.ts

@@ -1,6 +1,14 @@
 import { Provider } from "@/provider/provider"
 import { Log } from "@/util/log"
-import { streamText, wrapLanguageModel, type ModelMessage, type StreamTextResult, type Tool, type ToolSet } from "ai"
+import {
+  streamText,
+  wrapLanguageModel,
+  type ModelMessage,
+  type StreamTextResult,
+  type Tool,
+  type ToolSet,
+  extractReasoningMiddleware,
+} from "ai"
 import { clone, mergeDeep, pipe } from "remeda"
 import { ProviderTransform } from "@/provider/transform"
 import { Config } from "@/config/config"
@@ -183,6 +191,7 @@ export namespace LLM {
               return args.params
             },
           },
+          extractReasoningMiddleware({ tagName: "think", startWithReasoning: false }),
         ],
       }),
       experimental_telemetry: { isEnabled: cfg.experimental?.openTelemetry },