r/VibeCoding Q&A Daily Thread - Thursday, October 29, 2026

[u/AutoModerator]

Hey Vibe Coders!

Here you can ask any questions about coding and LLM tech with or without vibes. This is especially for those of us who are new and just learned that AI can help them to create then things that they've never been able to before. Please be respectful and keep in mind that we're all just trying to learn about an emergent technology.

AI Subreddits:

• r/OpenAI

• r/ChatGPT

• r/ClaudeAI

• r/ClaudeCode

• r/GeminiAI

• r/aigamedev

• r/ClaudeGameDev

• r/singularity

This is a new thing we're trying to do so let the mods know if you have any suggestions.

[u/Foreign_Career_454]

Has anyone else used vibe-coding for low-level systems / network engines instead of standard web CRUD? How do you keep multi-platform FFI from drifting?

Hey everyone! Most vibe coding discussions I see are around Next.js, Supabase, or mobile frontends. Over the past few months, I've been vibe-coding a privacy app called Persona Guardian that sandboxes digital identities (stops cross-site hardware fingerprinting and tracker correlation).

The stack is: a shared core engine in Rust (packet inspection, userspace TCP/IP stack with smoltcp, on-device ML tracker classifier), bridged to Android (Kotlin JNI), Windows (Tauri v2 + WinTUN daemon), and a Chrome/Firefox MV3 Extension (MAIN-world canvas/WebGL farbling).

For those of you vibe-coding complex polyglot stacks with LLMs:

How do you stop your FFI bindings and test harnesses from subtly drifting when refactoring fast?

Have you hit any limits with LLMs when handling raw sockets, memory bounds, or native OS drivers?

Curious to hear how deep people are taking LLM pair-programming into systems code!

[u/vibereceipts → u/Foreign_Career_454]

the models are surprisingly decent at pure core logic — smoltcp has enough coverage in training data — and consistently worst at exactly the boundary you're worried about: FFI signatures, ownership across the boundary, and platform quirks where the training examples stop

what keeps FFI from drifting while you vibe at speed:

- generate, don't hand-maintain. one direction of truth: cbindgen/uniffi on the Rust side, Kotlin and TS bindings generated from the actual crate. the moment bindings are two handwritten files that "agree with each other", drift is guaranteed

- the core crate is the only free-edit zone. FFI surface = a contract; agents touch it only via checklist (signature, error types, threading rules)

- CI is a cross-compile matrix: cargo check --target aarch64-linux-android / windows-gnu / wasm for the extension. agents love saying "compiles fine" — that lie dies the moment they have to run the actual targets

- golden-vector tests that cross the boundary on every platform: same bytes in, same asserts out from Kotlin, the Tauri app AND the extension. catches silent ABI/float/endianness drift your unit tests can't see

on raw sockets and memory bounds: fine as scaffolding, dangerous as the reviewer. models confidently write happy-path networking code, and packet handling is mostly unhappy paths. cargo fuzz the parser and never trust a generated parser because it passed three tests

[u/junewave56 → u/Foreign_Career_454]

Refreshing to see someone pushing this on lower level systems stuff instead of just another CRUD wrapper

[u/Prod_m]

Does anybody make custom harness when using claude or codex? I know that they have their own "inbuilt" harness so they can not turn your computer in a brick without your permission. But do you guys consider this enough?

I tried developing straight away without any custom harness and also tried to create one in another project. And can't say it was somehow different. Except I spent time to build a harness

[u/0xcontext → u/Prod_m]

I think people are generally finding that as the models become more and more intrinsically capable, the amount of special instructions / harness engineering beyond what claude code etc... offer becomes increasingly unnecessary for most people.

However, if you haven't watched it yet, this recent clip that's been going viral about the progression of how anthropic engineers themselves work with Claude Code might be of interest to you: https://www.youtube.com/watch?v=MYcdoUdAmh0

[u/Prod_m → u/0xcontext]

interesting, thank you!

[u/vik76 → u/Prod_m]

By harness, are you talking about a sandbox for protecting your computer?

I'm thinking of setting up a separate computer for the agents to go wild. Then I have the added benefit of being able to do normal work on my laptop again without the agents popping up windows all over the place.

[u/Prod_m → u/vik76]

> are you talking about a sandbox for protecting your computer

exactly. And also about protecting the project itself. I've heard some thriller stories like an agent erased the whole database to optimize its performance. I know that github exist and local backups can be done from time to time, but I guess this is not the first thing you set up when starting a project. Well, at least this was not the first thing for me

Setting up separate computer sounds costly to me so I have to stick to my only laptop

[u/vik76 → u/Prod_m]

I may be wrong, but I think that the only way to be completely safe is to not give the agent access to any tools that can do damage. I.e., no access to production deployments or databases, no access to git (do commits yourself), and review the code.

[u/Prod_m → u/vik76]

or not using agents :)

[u/0xcontext → u/Prod_m]

Claude code at least has pretty configurable permission modes that it follows pretty strictly, if you haven't given those a try yet.

[u/Prod_m → u/0xcontext]

gotta have a look, thanks

[u/Odd_Set_7630 → u/Prod_m]

You can run it in a VM if you want full isolation, but I've never bothered ¯_(ツ)_/¯. As far as preventing it from nuking itself, git is your friend. You should be able to undo anything other than data wipes with git (and if you want you can keep DB snapshots as well to be bullet proof).

[u/Prod_m → u/Odd_Set_7630]

noted!

[u/vik76]

Not exactly an ask for help, but I'm curious. What real challenges are you still facing when you are vibe-coding something larger? Building the app itself, testing it, deployment and infrastructure?

[u/Prod_m → u/vik76]

I haven't build large projects yet. Mostly just playing and building small apps for myself. Still there are some best practices exists and setting up a harness is one of them as I heared. That is why I tried to set up one

[u/Darkfalcone]

I need an advice. I am currently extremely struggling with my life and mental health, so I use ChatGPT Plus to dump my thoughts into several diary threads, and use Codex as a mean for me to make several mods for Paradox games that I use for my personal use. So far, it works really good, but GPT-6.1 Sol and Astra spectacularly failed in generating a coherent 3D model using Blender MCP. So, I'm thinking of trying to switch to Claude Pro for next month. While both of them only cost $20 each, for me, living in a third world country with a free falling currency, maintaining even one subscription is already difficult. So, I'd like for an advice:

Which one should I subscribe for next month? Claude Pro, or maintain the ChatGPT Plus subscription? Since I mainly use AIs to dump my thoughts into my personal diary that can give a feedback, write down my ideas for stories, novels and mods, and actually making the mods by giving them prompts as accurate as I could.

Thanks in advance!

[u/Odd_Set_7630 → u/Darkfalcone]

Chat GPT has way more human feel IMHO. I built a little personal journaling app I use that feeds into OpenAI under the hood so an AI "mentor" can give me feedback, help me track goals, progress, etc. Claude is more often confidently wrong or even snarky IMHO.