fix: max output tokens when setting budget thinking tokens (#2056)

Co-authored-by: rekram1-node <[email protected]>

2 files changed, 15 insertions, 1 deletions

diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index 50aa55cba..a9616cfd1 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -98,4 +98,18 @@ export namespace ProviderTransform {
     }
     return result
   }
+
+  export function maxOutputTokens(providerID: string, outputLimit: number, options: Record<string, any>): number {
+    if (providerID === "anthropic") {
+      const thinking = options["thinking"]
+      if (typeof thinking === "object" && thinking !== null) {
+        const type = thinking["type"]
+        const budgetTokens = thinking["budgetTokens"]
+        if (type === "enabled" && typeof budgetTokens === "number" && budgetTokens > 0) {
+          return outputLimit - budgetTokens
+        }
+      }
+    }
+    return outputLimit
+  }
 }
diff --git a/packages/opencode/src/session/index.ts b/packages/opencode/src/session/index.ts
index 8093f58a0..113cf67bf 100644
--- a/packages/opencode/src/session/index.ts
+++ b/packages/opencode/src/session/index.ts
@@ -1019,7 +1019,7 @@ export namespace Session {
           : undefined,
       maxRetries: 3,
       activeTools: Object.keys(tools).filter((x) => x !== "invalid"),
-      maxOutputTokens: outputLimit,
+      maxOutputTokens: ProviderTransform.maxOutputTokens(model.providerID, outputLimit, params.options),
       abortSignal: abort.signal,
       stopWhen: async ({ steps }) => {
         if (steps.length >= 1000) {