LLC operating agreements are for executing specifics between owning members regarding the share of ownership in the firm, the roles of the members, who can sign for the company and how one member may buy another member out plus many other considerations. Operating agreements are not required by government agencies but are very important to a company. They should be reviewed by a lawyer and notarized, then place in the official company files. You may download a free LLC operating agreement template at the "References" file in the BOX at the right margin of the site I maintain as an extension of my volunteer work: https://www.smalltofeds.com
Since you have not stated that you plan to have other developers share in the ownership of the firm (become members at a specified percentage). I believe you are in need of a job cost accounting system with a general ledger and subsidiary ledgers that allow you to set up individual projects and track them, executing contracts with your developers to track each project's direct cost. and pay developers under their individual contracts.
Job cost accounting systems also allows you to allocate an overhead amount from indirect cost (company operating expense accounts) based upon the weight each project bears in terms of direct cost as they run in parallel.
You can read about job cost accounting a bit more at the following two links. At the first link note that job cost accounting is required under all federal government service contracts for the type work you perform. * https://www.sage.com/en-us/sage-business-cloud/accounting/ * https://www.smalltofeds.com/2010/03/small-business-job-cost-accounting.html ** At the second link note a rudimentary application of the principles described above, with a simple upgrade from inexpensive Quick Books Software is an approach many of my clients use.
The 3 most vital element my clients must address in achieving what you have described in your profile are:
A long range financial plan (LRP) forecast the develops pricing based forecasts of direct and indirect cost against project and expense accounts. The same accounts are then replicated in the accounting system for tracking actual costs and payments to suppliers.
Contract formats and terms and conditions for suppliers (developers in your case) that are written to lock them into a statement work and financial/schedule baseline milestones that tie out to payment from the accounting system and apply overhead to yield a balance sheet and profit and loss statement.
Setting 1 and 2 up in advance of commencing work to avoid bottlenecks in processing and unhappy business relationships..
If you would like to correspond further on the above, please get back to me here at Micro Mentor and I will send you my personal contact information.