Calls, puts & mise en place

Appel & Mise

Vol. ITuesday, September 8, 2026 · 62° & cloudy on the UWSThe daily, for Jeremy Ettlinger

BTC$78,700-0.8%ETH$2,490+0.2%S&P 5007,718.60-0.4%

The lede

How well do agents use test and verification techniques?

Dan Luu · made the Sunday

Luu ran 26 testing regimes — TDD, property-based testing, Verus, Lean 4, Kani, plain fuzzing — against the same Zstd implementation task, and the default prompt with no testing guidance beat most of them. Telling an agent to do TDD produced twice as many tests that were smaller and more trivial, and formal-methods runs mostly proved vacuous properties like 0 < c ≤ window while the bitstream-reversal bug sailed through. If you are writing an engineering skill file this quarter, this is the study that says a technique handoff is not the same as a capability.

AI & Agents

Simon Willison

Creepy crawlies

Konstantin Ryabitsev reports that git.kernel.org now burns 14 CPU cores across five servers doing nothing but rendering commit HTML for scrapers, more than it spends on every form of legitimate access including clones. Anyone hosting a large surface of generated pages is quietly paying this tax, and the arithmetic is why prerendering to static assets keeps looking smarter every month.

jyn

We have a year to fix security everywhere

The argument is that vulnerability discovery has already fallen to open-weight models cheap enough to run on a hobbyist budget, so the binding constraint is now remediation speed — the staged rollouts, the physical-access boxes, the Windows Server 2012 still under a substation. The recommendations are refreshingly unromantic: fund security engineers, mandate testing frequency rather than techniques, and measure the end-to-end time from patch published to patch deployed.

Engineering & Leadership

Ameya Kanitkar, LeadDev

Cut AI-coding costs without slowing down

Median spend of $213 per engineer per week with a tenfold spread, and budget caps that 91% of Coinbase engineers never hit — which is the tell that caps are theater and visibility is the actual lever. The concrete win is unglamorous: an hour-long prompt cache instead of five minutes took one team's hit rate from 5% to 60% and halved the bill.

Web & Product Craft

Weird Gloop · made the Sunday

There's a new "Google Jail" for independent wikis

Roughly nine in ten wikis launched on fresh domains since the March 2024 core update rank for their homepage and nothing else, sometimes for a year, while the same content on an aged subdomain indexes normally. For anyone weighing a new domain against a subfolder on something old, that is no longer a branding question but a traffic one.

D2 / Terrastruct

TALA is open source

D2's proprietary layout engine goes MPL-2.0 alongside the language, and the interesting part is what it optimizes for — whiteboard-shaped architecture diagrams rather than the one-directional flow Dagre and ELK produce, with the option to pin some nodes and let the rest arrange themselves. The tradeoffs are stated plainly, including nonlinear scaling and a seed you may need to re-roll.

New York & the Table

Max Rivlin-Nadler, Hell Gate

Lyft made $24 million off Citi Bike last year

The DOT's mandatory filings show profit going from $1.8 million in 2023 to $6.8 million in 2024 to $24 million in 2025, driven by fee increases and the e-bike upcharge, after years of Lyft describing the system as a money loser. A clean case study in how far a public-private operator's public accounting can drift from its public posture.

West Side Rag

Meet the man who sells used books on the street outside Columbia

Paul Olson runs twenty-odd cardboard boxes on Broadway near 113th, four dollars a book, sourced from donations and AbeBooks, and needs no vendor license because books are speech. He recommends only what he has read himself, which is the one feature no recommendation engine has managed to ship.

Diversions

Leanne Ogasawara, Literary Hub · made the Sunday

Emily Wilson on complicated men and celebrating strangeness

Wilson is revising her Odyssey, dropping the one-English-line-per-Greek-line constraint she held herself to in 2017, and her defense of translating polytropos as "complicated" is really an argument about pacing budgets. Her rule — keep the strangeness in the worldview rather than in archaic diction — is a design principle wearing a classicist's coat.

Loose Change

Shawn Miller, Aeon · made the Sunday

Continental divide

Coolidge sold the Pan-American Highway in 1924 as a Highway of Friendship, and a Brazilian officer named Leônidas Borges de Oliveira spent a decade covering 17,769 miles to prove it possible, disassembling his vehicles and carrying them over the impassable stretches by mule. The Darién Gap that still breaks the road is not a terrain problem — Panama declines to build it because a roadless jungle makes a serviceable border wall, and half a million people walk it each year anyway. Two-thirds of North Americans believe the road was finished, and the free-movement fraternity it was meant to create ended up happening in South America instead, without the road.

The Back Page

Jacob Steinberg, The Guardian

Chelsea's midfield a headache for Alonso after Arsenal press advantage

Alonso refused to park the bus at the Emirates and got an early Rogers goal for it, but Moisés Caicedo's absence left a gulf in the middle that Rice ran straight through, and Reece James losing Ødegaard settled it. The encouraging read is that the intent was right and the personnel were not, which is the more fixable of the two problems.

Around town

Thu Sep 10 · 5:00pm

AI Search Meetup

307 W 38th St, Garment District

Retrieval is the part of the agent stack everyone ships badly and nobody writes up honestly. A room of people debugging the same thing is worth more than the talks.

professional

Sat Sep 12 · 4:00pm

R.F. Kuang: Taipei Story

Symphony Space, 2537 Broadway at 95th

A Saturday afternoon and a fifteen-block walk for a novelist who writes about translation, academia and empire with her elbows out. Home before dinner.

casual

Fri Sep 11 · 7:30pm

Serouj Kradjian and Band, featuring Samvel Yervinyan

Symphony Space, 2537 Broadway at 95th

A Juno-winning pianist and a violinist best known from a very different stage, playing Armenian material in the neighborhood hall. The kind of Friday that requires no train.

casual

Wed Sep 16 · 7:00am

Avalanche Summit

Chelsea Industrial, 535 W 28th St

A full day of the institutional-chain crowd talking about what actually settles on-chain. Day-job reconnaissance, and the hallway is the product.

professional

Quote of the day

“There's nothing I'd rather do than this. I can have real conversations about everything.”

— Paul Olson, who sells four-dollar books on Broadway

On this day

1966: Star Trek premieres on NBC with 'The Man Trap' — the talking computer arrives on television two years before Engelbart demos the mouse.

The puzzle corner

The Mini · Wordle · Connections

The road that was never finished, and the model that never learned to test.