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Migrating a production AI agent to GPT-5.6: 2.2x faster, 27% cheaper

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Re: Migrating a production AI agent to GPT-5.6: 2.2x faster, 27% cheaper

#81

We at Playcode.io - a company similar to Ploy are still using Opus 4.6. "Why?" you might ask. Because GPT 5.6 Sol, while fast and pleasant to use, is essentially the same model as 5.5 wrapped in new marketing packaging, just to avoid losing ground to Anthropic. In practice, it's the same quality: it generates the same garbage, tons of code, and can never solve even a single complex task. We simply don't trust it to w…

Did you just paste your marketing copy into a hn comment?

Re: Migrating a production AI agent to GPT-5.6: 2.2x faster, 27% cheaper

#82
My experience mirrors this: services like OpenRouter that promise “failover” are pretty much useless except for sandbox testing because models in production are not really interchangeable. Any production harness doing serious agentic work in production is dependent on more model-specific quirks than you would expect. And even if another model works without errors, performance and efficiency is a whole different story. Even the system prompt can and should be tuned to a model’s preferred speaking style, for example for Claude-like models because they were trained on it, while other models do better with other delimiters. Think of the whole harness, prompt, and model as one system, not really with modular parts that can be swapped out if you care about optimal performance.

Re: Migrating a production AI agent to GPT-5.6: 2.2x faster, 27% cheaper

#83
post #79

> Numbers like that buy a model a real migration effort. Such a silly choice of words. I wish the human directing the LLM writing the article put some effort into rewriting the worst examples of LLM style. > But it did extremely well, and the promise was immediate and specific: builds finishing in less than half the wall-clock time, at 27% lower cost, scoring at or above our incumbent on completed work. The way the L…

You are reading it wrong. Ask your LLM to read and summarize based on your style preferences. Better yet don’t read anything at all, just tell your agent to convert it to a skill file for it’s future reference..

this is probably sarcasm, but might actually try this. the visceral negative reaction i have to llm writing makes me instantly want to close the tab

Re: Migrating a production AI agent to GPT-5.6: 2.2x faster, 27% cheaper

#84
post #79

> Numbers like that buy a model a real migration effort. Such a silly choice of words. I wish the human directing the LLM writing the article put some effort into rewriting the worst examples of LLM style. > But it did extremely well, and the promise was immediate and specific: builds finishing in less than half the wall-clock time, at 27% lower cost, scoring at or above our incumbent on completed work. The way the L…

You are reading it wrong. Ask your LLM to read and summarize based on your style preferences. Better yet don’t read anything at all, just tell your agent to convert it to a skill file for it’s future reference..

Unironically, I think in the future we will have the option to run filters in our browsers that can reword articles to your preferred writing style. Like user stylesheets for text. I also assume it already exists out there, I've just been to lazy so far to look for it. It's a relatively obvious application of LLMs.

Re: Migrating a production AI agent to GPT-5.6: 2.2x faster, 27% cheaper

#85

We at Playcode.io - a company similar to Ploy are still using Opus 4.6. "Why?" you might ask. Because GPT 5.6 Sol, while fast and pleasant to use, is essentially the same model as 5.5 wrapped in new marketing packaging, just to avoid losing ground to Anthropic. In practice, it's the same quality: it generates the same garbage, tons of code, and can never solve even a single complex task. We simply don't trust it to w…

For PCB design 5.6 Sol/Terra is streets ahead of 5.5, and uses fewer tokens, so I'm not sure it can really be the same model.

Re: Migrating a production AI agent to GPT-5.6: 2.2x faster, 27% cheaper

#87
post #55
post #16

> we’ve made GPT 5.6 Sol the default model powering every Ploy workspace I would consider Luna for parts of the workload that touch actual tools. It is surprisingly capable and it runs fast. Sol is great at talking to the human and orchestration of agent calls, but it's just too expensive to use everywhere. You can get 5 Luna runs for the cost of 1 Sol run. Statistically speaking, going from one to five samples is a…

Statistically speaking if each part of the Luna run has a 90% chance of being correct, 5 of those is 0.9^5 = 0.59 = 59%. Or one Sol run being maybe 95% correct? Exact numbers vary of course. But then again having sol verify at end may be cheaper.

The goal is not 100% correctness. The goal is to demonstrate the current amount of variance / uncertainty to the planning agent.

If the planner sees that 4/5 Luna runs resulted in approximately the same summary, it may conclude that variance is low and that it is over the target. If all Luna runs are different, the planner can conclude that additional research rounds are required.

Re: Migrating a production AI agent to GPT-5.6: 2.2x faster, 27% cheaper

#88
post #10

> Numbers like that buy a model a real migration effort. Such a silly choice of words. I wish the human directing the LLM writing the article put some effort into rewriting the worst examples of LLM style. > But it did extremely well, and the promise was immediate and specific: builds finishing in less than half the wall-clock time, at 27% lower cost, scoring at or above our incumbent on completed work. The way the L…

Can we get over the detective work about if the text was written by LLM or not in 2026 already ? This is a lost cause, and we could instead focus on substance over syntax.

No.

Re: Migrating a production AI agent to GPT-5.6: 2.2x faster, 27% cheaper

#89

We run a lot of varied, tiny, simple workflows that were previously running on 5.4-nano and mini. We transitioned them to 5.6 and noticed exactly this range of improvement across the board. In a few cases, we had improvements in classification. I think a lot of people miss that for many companies, a model upgrade like this is basically a one liner. Even if you have an amazing model router architecture (which we do fo…

The first thing I used Sol for was to assess 5.6 on our workflows - previously, it was 5.5 for everything, as the quality on simpler models was just not good enough. We’re doing a mix of text and image analysis to extract explicit and implicit structured data from a steaming pile.

They do work pretty much as advertised. The bulk of our workload is now going via terra, which has cut our cost in half by itself, as well as improved response times by 50% - luna I am using as a backstop for opencv hits, and it is good enough, and so cheap as to almost be free - but very limited - and very fast. Sol only gave marginal improvements over terra for our workload.

I’ve also gotta say I’m impressed as to how well Sol ultra carried out the assessment itself - it made sound recommendations, and gave me a nice big dossier of “you should look at these outputs yourself and compare and consider” along with raw and digested data, and cpm for queries.

Anyway. Spent nothing beyond my pro sub, let Sol gnaw on it for a few hours, and my cost basis just dropped 50% and throughput improved by 100%. Win.

Re: Migrating a production AI agent to GPT-5.6: 2.2x faster, 27% cheaper

#90

My experience mirrors this: services like OpenRouter that promise “failover” are pretty much useless except for sandbox testing because models in production are not really interchangeable. Any production harness doing serious agentic work in production is dependent on more model-specific quirks than you would expect. And even if another model works without errors, performance and efficiency is a whole different story…

I believe part of the LLMOps (I don't like the term, but it is what it is) should be building a failover plan with proper testing that check tools trajectories and such. If you have these then you can sort the good enough models from cheaper to more expensive and have the failover you mentioned.

I saw people bulding a mapping of model->{{prompts}, {tools descriptions}, ...}, but that, to me, it feels extreme. I believe it is the model that needs to adapt to your prompts after a certain point. Models that fail to do so won't get our api requests as they will be out of the failoever roster.

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