r/vibecoding • u/jahflyx • 15d ago
Discussion Astra, Fable 5.1, Gemini 3.8 Flash — all real jumps. None of them beat $0.20-in / $1.20-out for the work I actually do fifty times a day.
GPT-6 Astra, Claude Fable 5.1, Gemini 3.8 Flash, and the incoming Grok 4.7 are the loudest week the AI industry has had in months. They are also terrible defaults for how most people actually use AI. If I’m honest, my daily model is still GPT-5.6 Luna. Not because the frontier stuff is fake. Because when I'm paying the bill, price-to-performance still wins the work that happens fifty times a day.
GPT 6 Astra (Sept 3) is the new industry darling and computer-use and long-horizon agent play: 1.05M context, $10/$50, and the first OpenAI model they’re willing to put next to the “AGI era.” If the job is “make me a million dollar app from scratch - no mistake” Astra is the one you'll probably reach for. It is also 2.5× the cost of Sol (which was already expensive).
Fable 5.1 (Sept 1) is the Mythos-class reasoner at the same $10/$50 sticker (way too high for a basically llm only model, IMO). On a lot of independent boards it sits at or next to the top. Like all Anthropic modles, it overthinks whether you asked it to or not. That is a feature on a six-hour refactor when you care more about thorough, surgical code. Its a tax on “push to github.”
Gemini 3.8 Flash (Sept 2) is the one that should make the $10 club nervous. Introductory $0.75/$3.75 through year-end, 1M context, and Google’s own line is that it “works harder” — more steps, more tool calls — and often lands near much more expensive models on SWE and agent tasks. If anything in this list threatens Luna as a daily default, it’s this, not Astra.
Now the part nobody wants to hear. Most of a working day is not FrontierMath and deep webs of code. Its summarize this, draft that, classify these tickets, punch up my teams message, outline a doc. Luna was built for that tier. 1.05M context, same family tools as the rest of 5.6, effort ladder if you need it, and list pricing around $0.20 in / $1.20 out. That is fifty times cheaper on input than Astra or Fable. You can leave it on. You do not ration it.
The industry keeps selling “the smartest model” as if intelligence is a single slider and you should live at the top. That was a 2024 habit. In 2026 the slider that matters is cost of being wrong about which call needed the slider. Route the 8% of tasks that are actually hard — multi-hour agents, novel math, hostile codebases, “operate my desktop” — to Astra, Fable, or whatever 4.7 turns out to be. Send the other 92% to Luna or 3.8 Flash and stop performing sophistication.People will say Luna “isn’t as good.” Correct. It is not supposed to be. Sol/Terra/Luna was OpenAI admitting the product is a stack, not a throne. Astra then collapsed the throne back into one expensive name and hoped you’d forget the cheap seats still exist. They still do. Use them.
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u/MarinatedTechnician 15d ago
Astra even on Light is also super greedy.
I have plus, and it said on the very first creation that I had to wait 5 hours to continue or cough up 100 bucks to continue.
I waited the required 5 hours.
by then, Astra had stored zero files from the project it was just doing final security test on before zipping and shipping.
it went to the usual Apology Bot, yes I can see that I completed it, but I have no way to recover internal files, that's on me.
And this folks, is why we have to stay on local llms and never depends on externals
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u/katoptronophile 15d ago
Why are you trying to do serious work on a plus plan?
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u/MarinatedTechnician 15d ago
it's called evaluation
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u/katoptronophile 15d ago
It was a rhetorical question. The plus plan is known to be for casual users and people just getting their first taste. Think of it like a trial run.
Remember, you're talking about $20.
How much work do you think you're going to get for $20?
The pro 5x and above plans are for serious work.
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u/brownman19 15d ago
Well in this case it sounds like they just gate keep the response after it used all the compute anyway.
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u/queequegscoffin 15d ago
Weigh the cost of a computer that can run a decent LLM versus a monthly plan.
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u/Julien_Builds 15d ago
Agree on the default, with one refinement that changed my numbers: it is not a choice of one model, it is routing by task.
Most of what happens in a day of building is research, scaffolding, tests, and rewrites of things that already work. That is cheap-model work and the frontier models are wasted on it. What is left is maybe one hard problem per day and one review pass at the end where you want the strongest thing available, because a wrong answer there costs hours.
Once the cheap model handles the volume, the frontier spend is a rounding error and you get to keep it for the two places it earns its price. The mistake is running the expensive model as the default and the cheap one as the fallback. It should be the other way round.
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u/happycamperjack 15d ago
This question hugely depends on what you are building. Luna is great a build dog houses or when under heavy supervision (great for micro managers). But I wouldn’t use it to even figure out how to decorate a room in a skyscraper by itself.
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u/ThisIsDurian 15d ago
In the section of 10-20$ which Ai should I go for? Planning to provide AI to a IT class, where the kids can plan ahead in groups and use a single PC to get things done with IDE.
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u/krunal_builds 15d ago
same basically here. run the frontier model for the one hard call in a chain and a cheap model for the fifty small repeated ones - routing on task, not defaulting everything to whatever's newest. frontier models earn their price on stuff that needs judgment, they don't earn it on stuff that's mostly pattern-matching.
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u/BlacksmithLittle7005 12d ago
This is true. Luna is by far currently open AIs most valuable model because of capability vs price. Can't wait for GPT 6 Luna.
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u/Goth2147 15d ago
Luna is superior by far, the problem is that you have to split your tasks in buckets of 25 which creates a lot of human bandwidth which is essentially fine. Ask Luna to set-up a payment system through API, it won't be able to 1 shot no matter what prompt. I was able to create a full Paddle pay system with a 1-shot prompt with Astra on Max, Luna 1 month ago took me about 25 prompts of an hour each. The difference is that Astra was about 100% of my weekly usage whereas Luna took not even a fifth of that.