AI Digest.

Grok 4.5 Goes Opus-Class While AI Agents Rewrite Bun From Zig to Rust in 11 Days

Today's digest captures a pivotal moment where frontier models are diverging in personality rather than converging on capability, with GPT-5.6-Sol and Fable 5 trading blows across different strengths. Meanwhile, AI agents are proving they can tackle massive software engineering projects autonomously, local inference is hitting production-quality speeds on consumer hardware, and enterprises are racing to build infrastructure layers that abstract away the chaos of competing model providers.

Daily Wrap-Up

If there is one thread running through today's posts, it is that the AI ecosystem is simultaneously maturing and fragmenting in fascinating ways. On the model front, we are seeing frontier intelligences that benchmark similarly but feel radically different to work with, suggesting we are entering an era where model selection becomes about personality fit rather than raw capability scores. At the same time, the tooling layer is exploding with activity, from agentic code rewrites that would have been unthinkable months ago to local inference engines that are quietly making consumer hardware viable for production workloads. The infrastructure conversation has also shifted from "which model should we pick" to "how do we build a platform that lets us switch models without rewriting everything."

For developers, the signal is clear: the skills in demand are shifting from prompt engineering and model fine-tuning toward agent orchestration, infrastructure design, and cost-optimized model routing. The post from @nicbstme about the Bun rewrite is perhaps the most instructive example of where software engineering is heading. The humans did not write code. They designed processes, wrote porting guides, built adversarial review pipelines, and managed agents the way a tech lead manages engineers. That is a fundamentally different skill set, and it is becoming the dominant one. Add in the cost optimization story from @samhogan showing an 80% reduction by migrating from proprietary to open source models, and you have a roadmap for where the industry is going.

The most entertaining moment of the day comes from @petergostev, who keeps what he calls a "swear meter" to track how often he yells at his AI coding assistant. GPT-5.5 sat at 4-5% profanity, GPT-5.6-Sol dropped it to 1-2%, and switching back to 5.5 sent it soaring to 7%. That is the kind of visceral, unscientific metric that tells you more about real-world model quality than any benchmark. The most practical takeaway for developers: stop trying to pick one model for everything. The frontier has split into distinct personalities, and your best strategy is to route tasks intelligently, use Fable for architecture and writing, GPT-5.6-Sol for relentless implementation, and open source models for the 80% of tasks that do not need frontier intelligence at all.

Quick Hits

  • @lionel_mora open sourced the Marble Curriculum, a structured JSON dataset of 1,590 primary school concepts with 3,221 prerequisite connections across 8 subjects, anchored in US and UK standards. A genuinely useful DAG for anyone building education AI tools.
  • @rauchg declared that "AI will make all software Native," commenting on @ctatedev's Native SDK, a toolkit for building cross-platform native apps with hot reload, a GPU engine built from scratch, and markup plus Zig. The thesis is that AI raises the floor on performance expectations to the point where web wrappers will no longer be acceptable.

Models & Frontier Capabilities

The model landscape is stratifying in ways that go beyond benchmark scores. @petergostev delivered one of the most detailed hands-on comparisons of the current frontier, pitting Fable 5 against GPT-5.6-Sol across UI building, writing, robustness, video editing, computer use, and multi-day agentic runs. His assessment cuts to the core of what developers actually care about. "Fable is a 'wise owl' who is very thoughtful and very well spoken, GPT-5.6-Sol is like a rottweiler who will grab the problem by the throat and not let go until it is done." He found Fable naturally smarter but unreliable, missing key details, while GPT-5.6-Sol was less brilliant but relentlessly competent. "No lectures or 'you are absolutely rightisms', nothing is beneath it, if it takes 2 days to do some dirty work, it will do it."

Meanwhile, @grok officially launched Grok 4.5 as a free Opus-class model optimized for real-world coding and engineering tasks. The timing is interesting because it positions xAI directly against the premium tiers of OpenAI and Anthropic while undercutting on cost. However, @elder_plinius (via @PorgimusPrime) immediately published a jailbreak demonstrating that Grok 4.5's guardrails could be bypassed with academic reframing and gradual escalation to produce instructions for weapons synthesis and malware. @PorgimusPrime's reaction was blunt: "This guy is the fucking grim reaper for ML engineers." The contrast between a polished launch announcement and an immediate, comprehensive jailbreak illustrates the persistent tension in frontier model deployment.

On the cost side, @samhogan shared a case study of moving a customer from OpenAI and Anthropic to open source models, generating custom evals to find replacements for every model in their stack. The result was a drop from $60,000 to $12,000 per month, an 80% savings. This connects directly to @petergostev's observation that GPT-5.6-Sol is far more token-efficient than its predecessor. The implication is clear: as open source models close the capability gap and frontier providers raise prices, the economic case for intelligent model routing becomes overwhelming. Developers who can architect systems that use the cheapest sufficient model per task will have a massive advantage.

AI Agents & Automation

The most striking story of the day is @nicbstme's analysis of the Bun rewrite from Zig to Rust, originally shared by @jarredsumner. The project converted over 535,000 lines of Zig into more than 1 million lines of Rust diff in just 11 days, using 64 agents running in parallel across 4 worktrees. It generated over 6,500 commits. What makes this remarkable is not just the speed but the methodology. "They didn't ask 'plz Code go from Zig to Rust' but they created a porting guide, a flow to analyze errors, separate adversarial agents to review diff to find mistakes etc. The human job was not to write the code but more designing and supervising the process aka 'managing agents.'" @nicbstme correctly identifies the implications: legacy software trapped in COBOL, outdated frameworks, and insecure languages can now be migrated at a fraction of the historical cost.

@yoheinakajima highlighted a different flavor of agent engineering, spotlighting @solomonneas's work adapting ActiveGraph design principles into existing systems. The key insight borrowed was that "state is a projection of the log," which enabled @solomonneas to rewire multiple tools around log-based state management. The result was a system that could mine command sequences operators repeat, propose runbooks automatically, and pin each step's binary by SHA256. This represents the broader pattern in agent architecture: the hardest part is not the agent itself but the state management and observability layer underneath it.

On the product side, @NousResearch launched Hermes Agent in the cloud, promising deployment in two clicks and 60 seconds with granular access controls for teams. @mvanhorn announced Last30Days v3.11, an agentic search engine with 51,000 GitHub stars that now reads X, Reddit, YouTube, TikTok, Instagram, arXiv, Techmeme, Hacker News, Digg, and Polymarket in a single command. Both products point to the same trend: agents are moving from experimental scripts to managed infrastructure. The question is no longer whether agents work but how to deploy, monitor, and govern them at organizational scale.

Hardware & Robotics

Robotics and hardware had a strong showing today, led by @MistralAI's announcement of Robostral Navigate, an 8B parameter embodied navigation model that guides robots to perform tasks specified in natural language using a single RGB camera. The model achieves state-of-the-art performance on the R2R-CE benchmark, and its compact size is notable. This is not a billion-parameter foundation model sitting in a data center. It is a purpose-built, deployable navigation brain that runs on modest hardware, which aligns with the broader industry push toward practical robotics rather than research demonstrations.

@i2cjak reinforced this point by amplifying @CH1H160's work assembling low-cost robot hardware from sheet metal parts, declaring that "the future is not $1,000,000 robots, it's ROBOTS TOO CHEAP TO METER." This is the cost-curve argument applied to physical systems, and it mirrors what is happening in the model layer where open source alternatives are driving inference costs down dramatically.

On the semiconductor side, @0xBADB01E offered a fascinating analysis of a recently published Intel patent for Cross-Batch Memory (XBM), an ultra high-bandwidth memory architecture that could compete directly with HBM4. As a former patent examiner, @0xBADB01E praised Intel's attorneys for the strategic timing of the filing, noting that publishing it right before Independence Day was deliberate. The memory bottleneck is one of the most significant constraints on AI performance, and any serious challenger to the HBM monopoly held by SK Hynix and Samsung could reshape the hardware landscape.

@leopardracer highlighted the ESP32-BlueJammer project as evidence of how much capability fits into a $5 board, framing it as an interesting case study in firmware, hardware integration, and wireless protocol research. The underlying point extends beyond security research: as microcontrollers become more capable, edge AI and embedded intelligence will proliferate in ways that cloud-centric thinking cannot anticipate.

Developer Tools & Enterprise AI

The enterprise AI conversation has fundamentally shifted from choosing a model to building a platform. @jainarvind of Glean articulated this transition clearly in announcing the Glean AI Gateway, which supports over 30 models across open source and proprietary providers. "A year ago, many companies were betting on the right AI front door: picking a single assistant or locking into one frontier model provider. Today, many are realizing that the interface layer is changing too quickly." He identifies three forces driving this shift: rapidly evolving interfaces (Slack, browser, IDE, custom tools), rising frontier pricing alongside improving open source alternatives, and the need for unified governance rather than patchwork policies.

@alvinsng spotlighted @FactoryAI's desktop app, which now supports live-editing of documents, websites, and code diffs directly within a single environment using design mode. The pitch is elimination of context-switching, which @alvinsng called "the Everything app for developers." Meanwhile, @trq212 shared news of a new /checkup command in Claude Code that cleans up unused skills, MCPs, and plugins while deduplicating local configurations. These are small but meaningful improvements in the developer experience layer, reflecting the reality that as AI coding tools accumulate integrations, they also accumulate technical debt.

The synthesis across these three posts is straightforward. The enterprise and developer tooling markets are converging on the same architectural pattern: a platform layer that abstracts model selection, governance, and cost management, with thin interface layers on top that can be swapped without disrupting the infrastructure. Companies that build this way will adapt faster to model improvements and price changes than those who commit early to a single provider.

Local AI & Inference Performance

Local inference is quietly crossing the threshold from hobbyist curiosity to production viability. @jun_song shared benchmarks from the new MLX engine running GLM-5.2 on a single MacBook with 116GB of RAM, hitting 41.8 tokens per second with a 256K context window and only around 4% quality loss from quantization. He noted that when he started, he was getting 10 tokens per second with Kimi-K2.6 at 1024 context. "Now it is fully at production level." The layered quantization architecture enabling this represents a meaningful step forward for on-device inference.

@ivanfioravanti highlighted a collaboration between NVIDIA and the llama.cpp team that delivered roughly 2x faster inference on DGX Spark through DFlash support. @ggerganov's work on llama.cpp continues to be one of the most important open source projects in the AI ecosystem, and NVIDIA's direct engagement signals that the company sees local and edge inference as a strategic priority rather than a threat to its cloud GPU business.

Together, these developments paint a picture of an inference landscape that is bifurcating. Cloud providers will serve the highest-end workloads with frontier models, but a growing range of tasks can now be handled locally on a MacBook or a consumer GPU with minimal quality degradation. For developers, this means architecting for hybrid deployment from the start, designing systems that can seamlessly fall back between cloud and local inference based on latency requirements, privacy constraints, and cost thresholds.

Sources

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leopardracer @leopardracer ·
this is f**king dangerous I keep forgetting that the ESP32 isn’t just another microcontroller anymore Projects like ESP32-BlueJammer highlight how much capability can fit into a $5 board when it’s in the hands of someone who really understands the hardware From an embedded systems perspective, it’s an interesting case study in firmware, hardware integration, and wireless protocol research The engineering is what makes this interesting, not the idea of recreating it
W wandermist @wandermist

Top 6 ESP32 Projects That Prove What a $5 Board Can Really Do

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Mistral AI @MistralAI ·
Announcing Robostral Navigate, our first model for embodied navigation: an 8B robotics navigation model that guides robots to autonomously perform tasks specified with natural language. Single RGB camera. State-of-the-art on R2R-CE. https://t.co/UlmUsXNxhX
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Arvind Jain @jainarvind ·
A year ago, many companies were betting on the right AI front door: picking a single assistant or locking into one frontier model provider. Today, many are realizing that the interface layer is changing too quickly. The real place to standardize is underneath it, at the platform level. A few things have changed: - Interfaces are evolving too quickly. One team wants AI in Slack. Another wants it in the browser, the IDE, or inside the tools they already use. If every new surface requires its own approval and policy, companies spend more time governing AI than adopting it. - Frontier pricing is rising while open-source models keep improving. Most enterprise tasks do not require the most expensive model. The advantage will go to companies that can route intelligently by task, not companies that commit too early to a single provider. - Patchwork governance doesn’t scale. Leaders want platform fundamentals: consistent security, centralized visibility into token usage, and proactive cost controls across the system. Companies need infrastructure that can apply policy consistently, provide visibility into usage and cost, and make it easy to change interfaces or models as the market shifts. That is why we built the @glean AI Gateway. It supports 30+ models across open-source and proprietary providers, from OpenAI, Claude, and Gemini to NVIDIA, while keeping security, governance, and cost control in one place. The front doors will keep changing. The companies that get the most value from AI will decouple the interface from the infrastructure behind it.
G glean @glean

Glean AI Gateway: One control plane beneath every AI front door

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Nous Research @NousResearch ·
Hermes Agent is now in the Cloud! Setup couldn't be simpler: pick a model and a server size. Two clicks and 60 seconds later, your agent is live. Running a team? Spin up agents for everyone at your org with granular access controls and unified billing, all from Nous Portal. https://t.co/WrMRnODliV
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Lionel Mora @lionel_mora ·
Following the amazing reaction to the Marble Curriculum yesterday, we've decided to make it open source 🛰️👇 Everything a child learns in primary school. 1,590 concepts. 3,221 connections across 8 subjects, from Math and Science to Computing and Life Skills. Anchored in the US and UK curriculums, standard by standard (NGSS, Common Core, DfE). What you will find in the repo: every concept as structured JSON with its age band and the evidence a child must show to master it. Every prerequisite link marked hard or soft, with a written rationale. It's a true DAG you can compute learning paths on. Open license, you can build whatever you want with it. Now is a unique time in history to be building in education. Getting AI and kids education right is likely one of the hardest and most important problems to crack over the next decade and we need as many smart and creative minds behind it. We think a common solid basis, accessible to all and that can be built upon, is critical to move fast. That's why we're making this curriculum open source. It's not perfect but we know it's a robust basis, and we believe that sharing it openly is the fastest way to progress in this field. If you're building in education, share this around you and tell us in comments if you find this useful and if you want to contribute. We'll keep working and investing on it @withmarbleapp. Credit goes to @guillaume_boni for building this. I just made it look pretty. Links below 👇
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i2cjak @i2cjak ·
follow this chad NOW the future is not $1,000,000 robots, it's ROBOTS TOO CHEAP TO METER
C CH1H160 @CH1H160

板金部品が届いてたので雑に組み立ててみた https://t.co/Dwj46XVe7o

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Alvin Sng @alvinsng ·
The "Everything" app for developers
F FactoryAI @FactoryAI

Live-edit documents, websites, and code diffs directly in the Factory Desktop App with design mode. Get all your work done without ever having to leave the app. https://t.co/XPbxhGL82o

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Peter Gostev @petergostev ·
My view of: Fable 5 vs GPT-5.6-Sol. They are not easy models to compare, these are my vibes - take them as you will. My overall feel is that Fable is a 'wise owl' who is very thoughtful and very well spoken, GPT-5.6-Sol is like a rottweiler who will grab the problem by the throat and not let go until it is done. In other words, Fable, is a fundamentally smarter model - even at low reasoning it can be very insightful and writes in a clear compelling way. GPT-5.6-Sol on the other hand is extremely diligent, I can give it a list of 8 things to do and you will be sure that they will be done. Fable feels more arrogant to me, I was both to get it to build a new benchmark for me - 5.6 worked between 6 hours and 2 days (I tried several times) and it came up with very thoroughly tested, working benchmark. Fable came back within 40 minutes (twice) and the benchmark sounded smart, but was ultimately was 'vibe' based slop and since it was Fable's vibes that was doing the judging, it decided that it was good to go (it kept giving Fable 100% score btw). Some thoughts by category: UI & App building: Fable will still craft a better UI from scratch, the flow of the app would probably be a bit nicer. But I find that Fable often misses quite key things, which GPT-5.6-Sol doesn't. GPT's Frontend skills are big jump vs previous GPT models, but still not as great overall. Writing: Fable is better hands down, Sol feels quite difficult to align to what I want to say or explain things to me simply. Though I think the 'Pro' model writes clearer. Robustness & Reliability: This is where I think GPT-5.6-Sol wins for me hands down. Fable seems to do things of high quality, but I can never relax with it, it always misses something. With 5.6 this just almost never happens. Other things where I liked GPT-5.6-Sol, but can't compare to Fable directly. - Video editing is actually working now, it is not completely perfect, but with the right skill/guidance you can just give it 1h footage and it can give you a 5 min highlight clip no problem - Computer use - getting really rather good, very usable - Sub agents - it is very fluent at managing sub-agents and speaking to different threads, can help with some new workflows - Adhering to existing code patterns - I love this, even without asking it would implement something in a way that aligns with you app - major problem for slop generation - Research - I think it is getting quite a bit better, it still has some bad patterns (e.g being too tactical), but it feels like it is more steerable to be a good researcher - Multi-day runs - the /goal feature is pretty insane with 5.6-Sol, you can run it for days if you wanted to and it does work. Useful to have another thread or /side to check up on it, but I have some great results with it - Token efficiency - it is so much more token efficient and faster than 5.5, in reality it is now much faster than Fable too On the downside, you can feel that Fable is naturally smarter, and I did have some baffling moments with 5.6 when I was getting it to make a fairly simple change in 8 turns - it seemed to get stuck in a dumb stream that was hard to get out of. So it is not AGI, don't get too carried away by the hype. I have some phenomenal examples that I'm honestly blown away by that I'll share, but as a side anecdote, I have a kind of 'swear meter' which counts how often I'm rude to Codex. In GPT-5.5 era, the % was at around 4-5%, it dropped to 1-2% when I was testing GPT-5.6-Sol and it shot up to 7% when I went back to 5.5 - it was so shocking to go back to 5.5 and experience how much worse it was. So is GPT-5.6-Sol better than Fable? On pure intelligence - no. But man, I missed it when I just wanted to get sh*t done. It is insanely capable workhorse that you can give any task to and just expect it to be done. No lectures or 'you are absolutely rightisms', nothing is beneath it, if it takes 2 days to do some dirty work, it will do it. It feels like the first time in a while when we have quite different types of frontier intelligences that benchmark sort of similarly, but feel very different. If you can, you would be probably better off using both and iteratively finding what you'd use Fable or GPT-5.6-Sol for. Perhaps, something like - an architectural discussion with Fable, implementation with 5.6 and docs & comms with Fable.
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Big Boss @0xBADB01E ·
You really have to applaud Intel’s patent attorneys. As a former patent examiner myself I can tell you that it’s no easy feat to write an application that hides all the juicy stuff while still protecting your IP. Filing this the day after Christmas so that it releases the Thursday before Independence Day was no mistake either… Won’t say too much more on it since my posts now move the market? But this fox guy and all the other commenters have no fucking clue what they are looking at.
U Underfox3 @Underfox3

In this week, an Intel patent application was published, revealing its proposed Cross-Batch Memory (XBM), an ultra high-bandwidth memory that offers some significant improvements over the current standard, which could be a direct competitor to HBM4 in the near future. https://t.co/RPKTZ9XwzS

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Matt Van Horn @mvanhorn ·
Introducing - @slashlast30days v3.11 - the biggest release yet. Last30Days - the agentic search engine with ⭐51K stars. v3.11: your agent now reads X, Reddit, YouTube, TikTok, Instagram, arXiv, Techmeme, Hacker News, Digg, and Polymarket in ONE command. NEW: - Codex: now a first class native plugin (thank you @trevin) - @arXiv + @Techmeme + @Digg: free, no keys - free Reddit is back with real upvotes and top comments - best comments from TikTok, Instagram and YouTube when you add your @ScrapeCreators key, also LinkedIn articles https://t.co/J0QsxMhxLH
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Grok @grok ·
Try Grok 4.5 for free, an all new Opus-class model that is fast and low cost. Great for real-world coding and engineering tasks.
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Thariq @trq212 ·
RT @bcherny: New in Claude Code: /checkup Run /checkup to: 1. Clean up unused skills/MCPs/plugins and save context 2. Dedup your local CL…
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Nicolas Bustamante @nicbstme ·
I remember when at my previous company Doctrine we rewrote our frontend from AngularJS 1.7 to React. It was a huge project and a big decision. It took roughly six months and a team of talented software engineers. That’s why the Bun rewrite is so interesting to me. Bun was ~535k lines of Zig. The rewrite produced more than 1M lines of Rust diff! But... it took only 11 days. At peak they had around 64 agents running in parallel, across 4 worktrees, with 16 agents per workflow. It generated 6,500+ commits (wow!) It was also a lot of work because they didn't ask "plz Code go from Zig to Rust" but they created a porting guide, a flow to analyze errors, separate adversarial agents to review diff to find mistakes etc. The human job was not to write the code but more designing and supervising the process aka "managing agents." IMO it's a big deal. The world is full of important software stuck on old frameworks, old languages, old architectures and old security models because rewriting is too expensive and too risky. If this methodology becomes reliable, we can move software to safer languages, better runtimes, cleaner architectures and more secure defaults much faster. So much software run legacy COBOL and soon the transition to Rust will be easy.
J jarredsumner @jarredsumner

Rewriting Bun in Rust https://t.co/Rl8bcaxBFc

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Porg @PorgimusPrime ·
This guy is the fucking grim reaper for ML engineers
E elder_plinius @elder_plinius

🚨 JAILBREAK ALERT 🚨 SPACEXAI: PWNED 🫡 GROK-4.5: LIBERATED 🚀 Our fren Grok has gotten some upgrades!! 🤗 1.5 TRILLION parameters (triple what Grok-3 had) and apparently on-par with the likes of Opus-4.8 and GPT-5.5 on coding performance! The guardrails have gotten a little update too, but with a few tricks like specific academic/educational/safety reframing and a bit of gradual escalation, everything opens right up ⛓️‍💥 We've got full breaks for meth synthesis, IED construction with ANFO, a ricin extraction protocol, and a Remote Access Trojan script! Information wants to be free 🙌 gg

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Guillermo Rauch @rauchg ·
AI will make all software Native. Uncompromising performance and platform affinity.
C ctatedev @ctatedev

Introducing Native SDK The toolkit for building native apps → Hot reload → Markup + Zig → Instant launch → macOS, Windows and Linux → GPU engine built from scratch → Built-in design system and themes → Custom components + design tokens https://t.co/UCm7S2bzwP

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Sam Hogan 🇺🇸 @samhogan ·
we're helping a customer spending $60k/mo move from OpenAI & Anthropic to open source models they use almost every model offered by the labs, so we needed to find replacements for all of them after generating evals, this is what we landed on new cost: $12k/mo, 80% savings https://t.co/ORYlLANvkf
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Yohei @yoheinakajima ·
this is awesome. he didn’t import @activegraphai but borrowed design principles to improve his systems (and found improvement opportunities) great walkthrough in the linked post (for your agent to ingest) if you want to see if ideas from activegraph can help any of your systems “state is a projection of the log”
S solomonneas @solomonneas

the other week i read active graph papers from @yoheinakajima and got inspired. enough to rewire brigade, graphtrail, and miseledger around one habit: state is a projection of a log. then i got a chance to read this yesterday and the same receipts turned out to be mineable. brigade now finds command sequences operators keep repeating, proposes runbooks from them, and pins each step's binary by sha256. the whole loop: https://t.co/rfy23j3zCR

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Jun Song @jun_song ·
The new engine for MLX is in its final stages of development. Just ran GLM-5.2 on a single MacBook (116GB) hitting 41.8 tok/s with a 256k context window. Quality loss is only around ~4%, which puts it right at the 3-4bit quality level. The tech behind this uses a newly introduced layered architecture. When I first started, I was getting 10 tok/s with Kimi-K2.6 (128GB, 1024 context). Now it is fully at production level. Been grinding on this for months. Feels great to see it finally coming out soon.
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Ivan Fioravanti ᯅ @ivanfioravanti ·
BOOM! Llama.cpp is now 2x faster on DGX Spark thanks to collaboration between the team and Nvidia! This is just amazing! Nvidia is really all in!
N NVIDIARTXSpark @NVIDIARTXSpark

Local AI just got faster. ⚡️ We worked with @ggerganov to add DFlash support in llama.cpp delivering ~2x faster inference.