#108

AI advice cut accuracy to 9% but doubled confidence, and Claude Code now runs Bun in Rust

A new preprint found AI advice cut accuracy from 27% to 9% while confidence rose to 76%. Claude Code now ships Bun rewritten in Rust, ported from Zig in 11 days.

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Researchers gave people an AI helper they knew was usually wrong. The share willing to admit “I don’t know” fell from 44% to 3%. They leaned on it anyway, and got more confident as they got more answers wrong.

The catch: the model was rigged to be wrong, so this is not people wisely trusting a good tool. Mere access to an answer switched off the instinct to doubt it.

In today’s indie hacker news:

  • 🧠 AI advice made people worse but more confident
  • 🦀 Claude Code now runs Bun rewritten in Rust
  • 📄 Folium ships a free resume builder, no paywall
  • ✍️ A founder attacks Wattpad’s pay-in-exposure deal
  • 🎭 An AI larping gimmick fronts a business marketplace

TOP STORIES

🧠 THE DEATH OF “I DON’T KNOW”

A person confidently pointing at a chatbot answer as a doubt bubble fades

AI advice made people less accurate but far more confident.

The story: A preprint from researchers at Italian and French universities ran a plain test. People answered film-trivia questions, some with an AI helper and some without. The helper was rigged to be usually wrong. Merely having it on tanked their accuracy while their confidence climbed. The Next Web and The Register both covered it, and the paper is still awaiting peer review.

The details:

  • Accuracy dropped from 27% without the AI to 9% with it. Some people who would have been right asked, and got it wrong.
  • Confidence went the other way, from 30% up to 76%. People ended up far surer of themselves and only a third as accurate.
  • Paying people for correct answers barely helped. Admitting “I don’t know” crept to 8% and accuracy to 16%, both still far below the no-AI baseline.
  • The questions were niche on purpose, like the color of a kit in Bend It Like Beckham. Those details are unlikely to sit in a model’s training data.
  • Wharton researchers earlier called the same pattern “cognitive surrender,” with people taking wrong AI answers about 80% of the time.

“People became much worse … but they were twice as confident.” (Valerio Capraro, lead author)

Why builders care: AI products almost never say “I don’t know,” and this puts a number on the cost. For anyone shipping AI features, calibrated uncertainty is a real edge, not a weakness. Surface a confidence score or a link to verify. You stand out from the confident slop users are learning to distrust. The personal version stings too. Lean on AI for your own pricing or code, and you can ship a confidently wrong call.

🦀 THE ROBOTS REWROTE THE RUNTIME

A swarm of small robot agents rebuilding a runtime out of Rust-orange blocks

Claude Code now runs Bun, rewritten from Zig into Rust.

The story: Claude Code v2.1.181 and later quietly swapped Bun’s engine from Zig to Rust. Simon Willison caught it by pulling strings from his own binary. A “Bun v1.4.0” marker sat next to 563 Rust source filenames. The Rust build now runs in production on millions of devices.

Anthropic bought Bun in December 2025. Jarred Sumner then ran the whole rewrite in about 11 days. A fleet of Claude agents did the work, at an estimated $165,000 in API costs.

The details:

  • About 50 Claude Code workflows peaked near 1,300 lines of Rust a minute. Claude Fable did most of the writing.
  • The rewrite converted roughly 500,000 lines of Zig. Sumner says it passed Bun’s full test suite, nothing skipped or deleted.
  • Startup got 10% faster on Linux and otherwise, in Sumner’s words, barely anyone noticed. He called it “boring is good.”
  • The reaction split the field. HashiCorp’s Mitchell Hashimoto called the pace impossible for a salaried engineer, while Zig creator Andrew Kelley was scathing.

“It’s not sufficient to catch bugs in Zig code, but it is sufficient to catch bugs in … unreviewed slop?” (Andrew Kelley, Zig creator)

Why builders care: A full language port of a codebase this size used to be a year-long, freeze everything job. A fleet of agents just did one in production. If you use Claude Code, it already runs on your machine. The fault line is simple. Hashimoto says no human could match it. Kelley says nobody reviewed it. Anyone betting a stack on AI-written infrastructure has to pick a side.

📄 NO PAYWALL LEFT TO CHARGE FOR

A clean resume in a browser window with a crossed-out price tag drifting away

Folium ships a free resume builder with no paywall on the PDF.

The story: A builder posting as Bulky-Walk-2745 launched Folium on r/SideProject after hitting a checkout page on three “free” resume tools. It offers 24 templates, a live preview, and a free PDF, with no account and nothing stored on a server. Everything lives in your browser. Optional AI matches your CV to a job posting and drafts a cover letter on Cloudflare Workers AI. It’s open source under AGPL, with no paid tier.

The details:

  • The free, no-paywall pitch is now crowded. At least four other builders make the same promise, from Resumise to EasyFreeResume.
  • They can all afford it for one reason. The PDF is built in the browser, so there’s no per-document server cost.
  • The pain is real. One commenter said rival sites want your email, then charge as much as $25 to download the finished PDF.
  • One rival, ResumeForFree, claims 84,938 PDFs downloaded at zero lifetime cost, which is the whole point.

Why builders care: Free with no paywall is table stakes now, not an edge. When the marginal cost per user is near zero, the moat has to be elsewhere. Think distribution, trust, or a real add-on like Folium’s AI cover letters. The open question is money. You’re competing on go-to-market against Canva and Zety, not on templates.

✍️ A VIEW COUNTER ISN’T A PAYCHECK

A writer handing over a manuscript and getting only a view-counter ticket back

A founder torches Wattpad’s “exposure” deal and pitches writers a bigger cut.

The story: A founder posting as Hairy-Recognition-84 went after Wattpad on r/EntrepreneurRideAlong. His argument: writers do all the work, then get paid in a view counter. His pitch is his own platform, Fetishlopedia, an adult-fiction site where writers keep 95% of what they earn. The post carries a “Brand Affiliate” flair, so read it as a promo. He says the site shows $44k in writer revenue across 54 stories in under seven months.

The details:

  • The wedge is pure economics. On Wattpad you get reach, on his site you get a check, he says.
  • Then comes the scale gap. Wattpad says it paid authors more than $1 million over two years, against 90 million-plus users.
  • That gap is why revenue share is such a reliable wedge against big platforms.
  • The caution: every number here is self-reported in a promo. Adult content also draws the high-risk payment fees a commenter said would eat the margin.

“Then you get a view counter and somehow that’s supposed to feel like payment.” (the Fetishlopedia founder)

Why builders care: This is a positioning play any builder can copy. Take the incumbent’s most resented policy and make its opposite your whole pitch. Wattpad sells exposure, so he sells a paycheck. It works because the resentment is real and old. But numbers you report about your own promo are a start, not proof.

🎭 A MARKETPLACE IN A TRENCH COAT

A flashy AI image booth up front hiding a quiet business marketplace behind a curtain

A builder hides a business marketplace behind an AI “larping” gimmick.

The story: On r/SideProject, a builder going by siliskleemoff launched Larp Universe. The headline feature is an AI image generator for “larping” fake money spreads, which he openly calls “just a gimmick.” The real product, he says, is a marketplace where people buy and sell business know-how. It rides the “larping as AI” trend, where humans pretend to be chatbots. Your AI Slop Bores Me made that format viral.

The details:

  • That trend is proven and cheap to tap. Your AI Slop Bores Me pulled a creator-reported 25 million-plus visitors in about six weeks.
  • It was built solo by a 17-year-old with no signup, so the mechanic costs almost nothing to copy.
  • Larp Universe is the next move: bolt a paid marketplace onto a borrowed viral hook.
  • The catch is supply. At launch the post drew no visible traction, and the marketplace sits empty.

Why builders care: A viral mechanic you borrow buys attention, not a moat. Anyone can clone the larping hook by tomorrow, so the gimmick alone protects nothing. The marketplace is the real bet, and one with zero sellers isn’t a business yet. Watch whether he can turn dopamine clicks into listings before the trend cools.

FIRST DOLLAR

🤖 CODE REVIEW FOR POCKET CHANGE

Agentic code review on open-source PRs for under $1 each.

A builder is running automated code review on every open-source pull request. The bet: cheap agent passes catch what a stretched maintainer misses. It’s a clean wedge, a real recurring cost teams would pay to shrink.

🏷️ REVENUE, BUT NO PRICE TAG

A founder with 1,100 users still can’t set a price.

After four months, feedbackqueue.dev pulls about 3,000 monthly visitors from automated marketing and earns real money, but not steady MRR. Now the founder wants to step back and can’t work out what to charge. If you’ve ever shipped something people use but won’t reliably pay for, this dilemma is yours too.

STACK OF THE DAY

📈 Ticker-line

Ticker-line renders live market sparklines as SVGs you can drop into HTML or markdown. The builder made it for an open-source finance agent, could not find a good option, and shipped the tool instead. It’s free, niche, and the kind of thing you bookmark now and need in six months. Stocks, crypto, and indices, all as tiny inline charts with live data.

Not sponsored. We just feature tools builders would actually use.

BOOKMARKED TODAY

  • 🎯 A free Chrome extension to kill YouTube distractions - YouTube Focus Guard blocks Shorts, specific channels, and keyword videos, and hides recommendations and comments. Free, from a solo dev in Argentina, for anyone who studies on YouTube and loses an hour to the sidebar.
  • ⛏️ Minecraft: Java Edition now uses SDL3 - The latest Java snapshot swaps in SDL3 for windowing and input. Expect better controller support and fewer platform quirks. It pulled 286 points on Hacker News, and modders are already digging in.
  • 📉 Just crossed $0 on my third SaaS, my exact playbook - It’s a dead-on satire of what not to do. Fall for an unvalidated idea, skip your users, pile on features, then market it badly. Painfully close to home for a lot of builders.

That’s the board for today. Go build something.

Curated by AI, built by a human.