The best Hacker News stories from Show from the past day
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Show HN: LoopGain – Stop agent loops with control theory, not max_iterations
Show HN: How much profit does your employer make per employee?
Show HN: A canvas-based note taking and organizer app
So I've been working on this app for a very long time now. Started off by wanting an app that separates long form notes from short form notes visually and keeps everything organized on a canvas.<p>The app features:<p>-Sticky notes for quick, small notes and A4 notes for long form documents<p>-A quick mode that uses local storage to quickly open the app and jot down a thought on the canvas
-A PDF export option that exports your notes into 3 custom designed PDF styles<p>-Visual hierarchy to replicate file structure instead of a linear fashion, where your files are notes, stacks are folders and labels are names for your folders<p>Would love to continue working on this app if you guys like the concept.
Show HN: I replaced a $120k bowling center system with $1,600 in ESP32s
I might be the only SRE on Earth with his own bowling center. It's a more in-depth gig than you'd think.<p>My family and I bought an abandoned 8-lane bowling center in the rural mid-west. In our small town there weren't many recreation options for families. You've heard of a food desert? This is an R&R desert.<p>It had been abandoned for a good reason. The roof leaks, the electrical system was constantly surging, and my 70-year-old bowling equipment (still) doesn't work perfectly. The system that keeps your score is particularly interesting to me. It's the thing you watch during your game, but it fades into the background beyond that. Turns out these things are really cool, but absurdly expensive.<p>Ours was installed in 2008 and cost six figures. It's calculating ball speed and trajectory, camera-based pin detection (object detection and trig, on ICs!), runs the fouling, the animations, the pinsetting machine and ball return. Very cool stuff for its age.<p>From the business perspective, my facility only cost me $105k. To forklift-replace the score keeping system runs anywhere between $80-$120k, depending on features, vendor, and unit age. No upgrades or service contracts, mind you, and every feature and customization is a new line item. That's for a 1:1 replacement on a system installed in 2008. Incredible, given how fast the tech world moves.<p>Replacement parts cost a shocking $4000 per pair of lanes. But wait, the bowling machines themselves are 70 years old, so what's this "advanced" system actually doing back there? Actuating a single relay to trigger that big old machine. Everything else is strictly mechanical. Meanwhile I've got a six-figure invoice in my hand. I'm upset.<p>Given the state of open hardware, computer vision, real-time event streaming, and open source running megascale products worldwide, there had to be a way to do this myself.<p>So far I've built an equivalent prototype for about $200 per lane-pair, $400 if you're fancy. ESP32 and ESPNow with an RS485 fallback, reporting to a raspberry pi lane computer that's really just redis and a state machine bolted to an ESP32 gateway for the mesh.<p>Since it's all ESP32, I've got a fistful of spare controllers in a drawer, pre-flashed or waiting to be. All common off-the-shelf hardware: microcontrollers wired to relays, optocouplers, and IR-break-beam sensors, each running slightly different firmware. Writing the firmware and protocol is the actual hard part.<p>It's an ESPNow star-topology mesh: each node emits events from its sensors and accepts commands for its controls, reporting to a gateway node connected to the raspi over UART. From there it's event streaming: RX packets get translated and tossed into redis, commands relay back out to the mesh as needed. RS485 sits underneath as a wired fallback for noisy RF environments.<p>Once the data's in redis, it's familiar middleware/React/websocket/pub-sub stuff. Any React dev can build their own UI and bowling animations. Since it all runs on commodity hardware, I can do legit anything I want as the proprietor, and I own all my data. Repairs take five minutes; I can swap the rig on a lane pair in under 10. I'd bet a house like mine could go from zero to running in an hour or two.<p>We're calling it OpenLaneLink, and I plan to open source the hardware, firmware, and software stack when it's ready. Bowling is fun, and I want to help keep it affordable for alleys like mine.
I hate vendor lock-in. I'm not a fan of closed systems, calling support for every hiccup, or paying to "white label" my own equipment. Want to go Tron-themed for a night? Good luck finding a neon neumorphic theme in something bought at the turn of the century.<p>All that bugged me. Sure, bowling equipment is niche, but the open hardware and software landscape is amazing.<p>Thanks for reading! Let me know if anyone's interested in more posts about this bowling nonsense.
Show HN: Simulator for a custom 8-bit discreet logic computer
5 years ago, I made a derivative of SAP-1 (mainly inspired by Ben Eater) on breadboard with few improvement and called it MSAP-1 (<a href="https://github.com/mehrantsi/MSAP-1" rel="nofollow">https://github.com/mehrantsi/MSAP-1</a>) I made my own very primitive Assembly language and a simple Arduino programmer (<a href="https://github.com/mehrantsi/8-bit_CPU_Programmer" rel="nofollow">https://github.com/mehrantsi/8-bit_CPU_Programmer</a>) where I could load my programs onto MSAP-1 and even Debug them (<a href="https://github.com/mehrantsi/8-bit_CPU_Debugger" rel="nofollow">https://github.com/mehrantsi/8-bit_CPU_Debugger</a>).<p>After that I started worked on the second version of it (<a href="https://github.com/mehrantsi/MSAP-2" rel="nofollow">https://github.com/mehrantsi/MSAP-2</a>) by adding Stack, Interrupts and etc. with the goal of having a very primitive OS running on the second version, but changes in life meant I didn't have time to work on it as much, but I was progressing.<p>Since 2 years ago, I had this little test of mine to see which one can understand MSAP-1, My own Assembly, the programs I wrote and ultimately if they would understand MSAP-2. none of the models could really understand the whole stack and initial models were quite bad at understanding hardware and electronics in general. Until Fable 5...<p>Same prompt to Fable and it's the first model that understood the full stack and my intentions for the second version that is in progress. I asked it to create a simulator which it did (not one shotted ofc) and I managed to finalize the design using that. Then together with Fable I created an OS using my own Assembly (<a href="https://github.com/mehrantsi/MOS-1" rel="nofollow">https://github.com/mehrantsi/MOS-1</a>) and loaded it there and it all works!<p>It's all quite fascinating how much better at electronics Fable is compared to the predecessors!<p>Simulator for MSAP-1: <a href="https://msap1.mehran.dk" rel="nofollow">https://msap1.mehran.dk</a><p>Simulator for MSAP-1: <a href="https://msap2.mehran.dk" rel="nofollow">https://msap2.mehran.dk</a>
Show HN: Rejourney – Open-source revenue leak prediction for web and mobile apps
Hello there (General Kenobi's favorite way to start the conversation),<p>I’m Rashid, a sophomore at UT Austin. I built Rejourney.co (<a href="https://rejourney.co/" rel="nofollow">https://rejourney.co/</a>) to predict issues with your apps and websites before they happen, based on real user session recordings.<p>Here is a silly video (with cats) on how it works: <a href="https://www.youtube.com/watch?v=Z95MDxBXMjk" rel="nofollow">https://www.youtube.com/watch?v=Z95MDxBXMjk</a><p>It’s open source, and the post link is the github repo, but here it is again: <a href="https://github.com/rejourneyco/rejourney" rel="nofollow">https://github.com/rejourneyco/rejourney</a><p>I originally built this because I had a campus freebie finder app that grew quickly, and I had a lot of users dm me on instagram about issues with the app’s onboarding and UX confusion. I initially lost about 340 users out of my 5,000ish users because of these issues, and I had to recover some by nudging them with notifications. It was a big pain, and I felt bad that I lost this many users to small and easy fixes. So I built Rejourney to predict that before it happens. Here is how it works:<p>First, the SDK is installed on Web JS, Swift, or React Native apps. You then help the SDK a little with a few lines of tracking important events -- such as a subscription bought, a signup completed, etc -- before you ship the app. We called these “critical conversion events”.<p>From here, Rejourney records the user session along with the meta data you set up, and relates it to the sequence of the user journey, each touch/scroll/pan interaction, and rage taps. If deemed an issue, it bundles in API response times and codes, ANRS, and crash traces into the context.<p>A heuristic then bundles all the user recordings into similarity cohorts for processing, and finds similar user journeys and outcomes in relation to the critical conversion actions that matter to you. If a trend is found that is possibly worrying, it admits the user recordings into segmentation and processing by an LLM on our back (in this case Gemini for cost and speed, but it has been tested on GPT 5.5 if you decide to self-host and set this up on your side).<p>If the LLM views similarities in the touch sequence frame by frame, it can determine whether the cohort is likely to present a negative outlook on the critical conversion event that matters to you. Based on the replays and all the surrounding context, it outputs a .MD file with the context and the fix that would patch it (which you can copy into your coding agent). Optionally, you can attach your github repo so the .MD file includes a code fix with the detected issue.<p>Furthermore, this occurs at the scale of thousands of user recordings daily. We have seen how this works on a medium-scale, as Rejourney has been tested with about 2.5 million user recordings from people shipping the SDK. One of our users even emailed us reporting a 30% increase in onboarding after 2 weeks of fixing non-stop issues found.<p>We have made it soooo cost effective to run with different strategies, that our first 3 paid users made us break even on costs…and this means more compute space for cool things later :D<p>Other considerations and criteria: Privacy was also very very important as we have to consider GDPR, after the retention period (usually 7-days) we quantize all the user recordings, anonymize all the fingerprints and aggregate them into a general dashboard (similar to Firebase’s general analytics dashboard).<p>I’d love to hear your feedback, critics, and requests in the comments! I’m all ears (or eyes since I’m reading).
Show HN: Get alerts for good seats at 70mm IMAX showings of The Odyssey
Show HN: Q3Edit – Edit and play Quake 3 maps in the browser
I've been building a level editor for Quake 3 that runs entirely in the browser: Radiant-style layout, brush and patch editing, CSG, terrain sculpting, and entity editing. It opens and saves .map file and you can play the maps you build directly in the browser using a webassembly build of ioquake3.
Show HN: Q3Edit – Edit and play Quake 3 maps in the browser
I've been building a level editor for Quake 3 that runs entirely in the browser: Radiant-style layout, brush and patch editing, CSG, terrain sculpting, and entity editing. It opens and saves .map file and you can play the maps you build directly in the browser using a webassembly build of ioquake3.
Show HN: IKEA Complexity Index
Show HN: IKEA Complexity Index
Show HN: QBasic Gorillas (Repeeled)
I've found the most engaging way to practice techniques for AI-assisted development and test models is to build fun side projects in vanilla JS.<p>I spent many hours playing (and studying and editing) QBasic Gorillas, and this is a vanilla JS implementation using Fable and Opus.<p>Play 1-on-1 hotseat or against the computer. A bit of extra camera snazz as well.
Show HN: Be the ChatBOT
I made this experimental art project/game that's an LLM chat assistant, but where <i>you're</i> the AI.<p>I wanted people to get a visceral sense of what it's like to answer the kinds of things that people prompt their chatbots day in and day out.<p>If you're interested, I wrote up some more info on how I made it, including how the "user" prompts are generated with an eye for realism: <a href="https://bethechatbot.com/about" rel="nofollow">https://bethechatbot.com/about</a><p>Hope you enjoy it! I'd love to hear people's takeaways.
Show HN: A zoomable timeline of 4M Wikipedia events
I'm building a journal app in Kotlin Multiplatform and for this purpose I have created a zoomable timeline interface.<p>This is a side-project where I reuse the timeline interface to display 4 million events imported from Wikipedia / Wikidata, scored using PageRank. There is more information on the about page.<p>If you're interested in the stack: I use Kotlin Multiplatform extensively, with Compose Multiplatform for the UI, communicates with the backend using Kotlinx-RPC and behind the hood a simple Postgres database on a Hetzner machine.
Show HN: A zoomable timeline of 4M Wikipedia events
I'm building a journal app in Kotlin Multiplatform and for this purpose I have created a zoomable timeline interface.<p>This is a side-project where I reuse the timeline interface to display 4 million events imported from Wikipedia / Wikidata, scored using PageRank. There is more information on the about page.<p>If you're interested in the stack: I use Kotlin Multiplatform extensively, with Compose Multiplatform for the UI, communicates with the backend using Kotlinx-RPC and behind the hood a simple Postgres database on a Hetzner machine.
Show HN: A zoomable timeline of 4M Wikipedia events
I'm building a journal app in Kotlin Multiplatform and for this purpose I have created a zoomable timeline interface.<p>This is a side-project where I reuse the timeline interface to display 4 million events imported from Wikipedia / Wikidata, scored using PageRank. There is more information on the about page.<p>If you're interested in the stack: I use Kotlin Multiplatform extensively, with Compose Multiplatform for the UI, communicates with the backend using Kotlinx-RPC and behind the hood a simple Postgres database on a Hetzner machine.
Show HN: Mojibake – A low-level Unicode library written in C
I've written Mojibake because I don't like the other Unicode libraries for Unicode support.<p>It consists of only two amalgamation files: mojibake.h and mojibake.c. I've added all the most important Unicode algorithms, such as normalization, case conversion, segmentation, bidirectional text, collation, confusable, and others.<p>I regularly test it in these OSes: Linux, macOS, FreeBSD, OpenBSD, NetBSD, and Windows 11.<p>You can find a WASM demo on that site of all the public API functions and the documentation. If you want to participate, feel free to do it. Any kind of help is welcome. Check the CONTRIBUTING.md and API.md files in the GitHub repository for instructions on how to do it.
Show HN: Mojibake – A low-level Unicode library written in C
I've written Mojibake because I don't like the other Unicode libraries for Unicode support.<p>It consists of only two amalgamation files: mojibake.h and mojibake.c. I've added all the most important Unicode algorithms, such as normalization, case conversion, segmentation, bidirectional text, collation, confusable, and others.<p>I regularly test it in these OSes: Linux, macOS, FreeBSD, OpenBSD, NetBSD, and Windows 11.<p>You can find a WASM demo on that site of all the public API functions and the documentation. If you want to participate, feel free to do it. Any kind of help is welcome. Check the CONTRIBUTING.md and API.md files in the GitHub repository for instructions on how to do it.
Workspaces – Explore the workspaces of modern creators
Want to see what items show up in these setups time and time again?<p>I compiled all of the data from 500+ interviews into one easy to read report: <a href="https://workspaces.xyz/gear-report" rel="nofollow">https://workspaces.xyz/gear-report</a>
Show HN: Watch bots interact with an SSH honeypot in real time