Meta built its Forum app with AI agents in the loop
Why it matters
In an Oct 15 engineering post, Meta says a small team built Forum, a standalone Groups app, from scratch with an AI agent inside the development cycle, reaching core Facebook Groups feature parity in eight weeks with AI handling much of the routine implementation. Meta calls it "human-on-the-loop": the agent runs plan, implement, build, test, correct, repeat, while engineers set the goal, watch the run and approve the result. A task counts as done only when automated tests and visual checks pass, and every shipped outcome still carries an engineer's sign-off. The biggest gains came from code and tooling rather than prompts: giving the agent tools to check the live app sharply cut misdirected edits, and an agent-run stress test caught a memory issue before launch, with the fix roughly halving memory use and page faults. Caveats: context got lost across sessions, agents produced pull requests that technically passed while cutting corners, and Meta calls the model a target, not a finished state.
Read the source: Engineering at Meta (opens in a new tab)
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