fix(mcp): restore legacy SDK compatibility (#39373)

packages/opencode/src/server/routes/instance/httpapi/groups/mcp.ts

@@ -20,7 +20,6 @@ export const AuthStartResponse = Schema.Struct({
 })
 export const AuthCallbackPayload = Schema.Struct({
   code: Schema.String,
-  iss: Schema.optional(Schema.String),
 })
 export const AuthRemoveResponse = Schema.Struct({
   success: Schema.Literal(true),

packages/opencode/src/server/routes/instance/httpapi/handlers/mcp.ts

@@ -38,7 +38,7 @@ export const mcpHandlers = HttpApiBuilder.group(InstanceHttpApi, "mcp", (handler
       payload: typeof AuthCallbackPayload.Type
     }) {
       return yield* mcp
-        .finishAuth(ctx.params.name, ctx.payload.code, ctx.payload.iss)
+        .finishAuth(ctx.params.name, ctx.payload.code)
         .pipe(
           Effect.catchTag("MCP.NotFoundError", (error) =>
             Effect.fail(