Calls, puts & mise en place

Appel & Mise

Vol. IWednesday, October 14, 2026 · 68° & clear on the UWSThe daily, for Jeremy Ettlinger

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The lede

Redesigning source control at Anthropic

Anthropic Engineering · made the Sunday

Merge volume went from about 2,500 changes a day in May to over 30,000 a day in September, and git stopped being the tool and became the bottleneck: a 100 GB main-branch history, 25 GB working copies, 25 million CI checkouts a day that would have meant 600 petabytes of git traffic, and several hundred mirrors getting harder to operate every week. The diagnosis is the part worth stealing — git is built for decentralized offline work, and essentially none of their clients are offline, so the whole design was pulling against them. So a seven-person team built Scion and moved the monorepo off git in five months: changesets in a write-ahead log instead of commits pointing at trees, refs as a compare-and-swap on one Spanner row, blame and path history as derived data recomputed rather than stored, and a fetch protocol where the client never tells the server what it already has and just pulls the immutable objects it's missing. The reported numbers are 99%-plus cache hits at every tier, roughly 200x less CPU and memory than the mirror fleet, checkouts from minutes to seconds, and a quarter of CI capacity handed back — and they are refreshingly direct that this is not a git replacement you can adopt, just ideas that the platforms could. Read it for the second-order detail too: they killed the global-lock merge queue because Claude fixes the resulting conflicts faster than humans notice them, and the engineers' job drifted toward saying no to agent-generated shortcuts.

AI & Agents

yyhh.org

AI is a tool and using it well takes skill

A direct answer to Rich Hickey's "'AI' is Not a Tool" from three days earlier, and the rebuttal lands because it concedes the real point first: outsourcing work does cost you the chance to learn it. Where it parts company is on the definition — a saw does not guarantee a straight cut, a compiler does an enormous amount of work without your supervision, and unpredictability is a criterion for judging a tool rather than a disqualification from being one. The useful line it draws is not tool-versus-automation but wielding-versus-delegating: the question is what you actually do with the output, and whether you know when the answer is wrong. He also takes a swipe at the industry's habit of saying "go rogue" and "conspire" about software, which makes engineering failures sound like motives.

Niko Matsakis

What agents mean for Rust (and vice versa)

Rust's lead language designer makes the argument that Rust's sudden popularity is not really about performance — it is that "if it compiles, it works" is an unusually good leash for a machine that writes a lot of code quickly, and the borrow checker's uniqueness reasoning is what lets proof tools like Verus check a function locally instead of chasing aliases across a program. His framing of design, construction and optimization as three pillars of a software factory is the practical takeaway: construction has moved fastest, optimization is a profiler-plus-agent feedback loop now, and design is still markdown-driven hope. Worth reading for where he says the language should go — more expressive types so agents stop fighting the compiler, an extensible compiler so verifiers stop pinning versions, and a north star of proving the unsafe code rather than banning it.

Engineering & Leadership

LeadDev

The reality of being a forward-deployed engineer

The FDE title is being handed out fast right now, and this is a first-person account of what the job actually consists of: reverse-engineering a legacy system with no documentation into a partial data dictionary, re-validating ingestion every time the real data arrives messier than the sample, and finding the workaround when the customer's ask falls outside what the product does. The honest detail is that his AI assistants invented column names and dropped required ones, so every output gets reviewed — which is the whole argument for why this role is translation work rather than coding work. If you are thinking about who in your org should be sitting with customers while the agents do the typing, this is the shape of the person.

Web & Product Craft

Cloudflare

Under the hood, off the hot path: how D1 scales to millions of databases

Every D1 database is one SQLite Durable Object, which makes creating millions of them cheap and makes the hard part bookkeeping rather than storage — so the design is a strict split where queries resolve through Workers KV at the edge and never touch the central Postgres that handles create, delete, import and time travel. The mechanisms are the good bit: each Durable Object heartbeats the control plane every thirty seconds with jitter to learn whether it still exists and what its account limits are, storage totals are kept by a one-second aggregation job rather than summing per-database rows, and free-tier row limits land as a daily flag in Quicksilver that the edge checks before running anything. Stale data is explicitly tolerated everywhere it can be. Growth numbers for context on why any of this was necessary: 15x more live databases in a year, 65x in two.

Christopher Phiri

Recreational Programming

A talk in defense of writing code for no reason at all — not side projects, not skill-building, not a portfolio, just the thing you make because you were curious how it would feel. The taxonomy is better than it needs to be (the Deep Diver building toy versions of real systems, the Language Explorer trying a syntax on for an afternoon, the Problem Solver shipping something good enough to stop the annoyance) and the closing rule is the entire argument: stop if it stops being fun. Useful counterweight if your evenings have quietly turned into a second job with worse deadlines.

New York & the Table

Eater NY

Daniel Boulud has opened his giant brasserie at Lincoln Center

Boulud Sud, Bar Boulud and Épicerie Boulud have been folded into one 10,000-square-foot Brasserie Boulud, which opened on the 8th and is running the greatest hits of all three off a single menu — seafood towers, French onion, steak frites, lobster soufflé, and the DB Burger back from the dead. It is a twenty-minute walk and a straight shot of French consolidation, and the DB Burger alone justifies a reconnaissance mission before the post-concert crowd works out it exists.

West Side Rag

At last, Riverside Park South turf fields almost ready to open

The last piece of the thirty-two-acre Riverside Park South — turf marked for softball and 7-on-7 and 9-on-9 soccer, a basketball court, three pickleball courts, and the park's first lights for night play — should open within weeks, having been promised for 2018. Contaminated fill from the old New York Central rail yards ate most of the delay, rising costs ate the planned pavilion at 66th, and designer Thomas Balsley still calls the whole thing "the interim park," which is the most Upper West Side sentence published this week. The lights are the real news if you have ever tried to get a pitch after six.

Diversions

Aftermath

Kitman gets that most of sports is actually just laundry

You are the equipment manager of a football club: screw the color-coded studs into the boots, line a ripped pair of shorts up under the sewing machine, fill and drain the sink while holding the scrub button, send it all down a tube to a pitch you only ever glimpse down a corridor. The match happens off-screen, every day ends with you tidying the locker room and sleeping in the janitor's closet, and the stated goal is to leave no trace you were there. Demo is on Steam now, full release early 2027, and it is the first football game in years whose fantasy is competence rather than glory.

Loose Change

Open Culture · made the Sunday

A 900-page pre-Pantone guide to color, from 1692

In 1692 a Dutchman named A. Boogert sat down and hand-painted his way through roughly 900 pages of watercolor, mixing every tone he could reach and then documenting what happened when you cut each one with one, two or three portions of water. He wrote it in Dutch, titled it a clearly lighting mirror of the painting art, organized it by Aristotle's theory of color because Newton had not finished his yet, and made exactly one copy — which means the most comprehensive color reference of the seventeenth century was almost certainly never seen by a working painter. It predates Goethe by 118 years, Werner by 122, and Pantone by 271. It sat in a library in Aix-en-Provence until a medieval historian found it in a French database, and the whole thing is now scanned page by page at full resolution, swatch after swatch after swatch, in the handwriting of a man who had no idea anyone would ever look.

The Back Page

West Side Rag

The Upper West Side teenager taking the soccer world by storm

Julian Hall is eighteen, has fourteen goals for the Red Bulls this season, scored in each of his first three USMNT caps against Peru, Chile and Mexico, and is — per the Rag — the youngest man to do that since Pelé. He also still lives in the same apartment his family moved into when he was seven, skipped the West Side Soccer League for the Manhattan Kickers at Pier 40, skipped high school for the professional track, and grew up playing in Riverside Park. His own account of his game is almost entirely mental: he does not want the build-up, he wants to know where the ball is going to be. Six regular-season games left before the playoffs.

Golden State of Mind

Joe Lacob has 32x'd his investment; how much higher can it go?

Sportico puts the Warriors at $14.5 billion, which is 32.2 times the $450 million Lacob's group paid Chris Cohan in 2010, and up 28% year over year despite Curry being a year older and the dynasty a year further back. The accounting is the interesting part for anyone who looks at asset prices professionally: nearly $900 million in revenue, a privately funded arena that is also the Bay Area's biggest concert landlord, and the Valkyries — two years old, already the most valuable team in the WNBA at $850 million — as a money-printing tenant in a building the same people own. The least valuable team in the league is now worth twice what Ballmer was mocked for paying for the Clippers. Brady Klopfer's question is the right one and he does not pretend to answer it.

Around town

Fri Oct 16 – Sun Oct 18

Paris Was a Woman, with the filmmakers in person

Metrograph, 7 Ludlow St, Lower East Side

The 1996 documentary on the women who actually ran literary Paris between the wars — the writers, the publishers, the bookshop that printed the book nobody else would — with directors Greta Schiller and Andrea Weiss in the room all three days. Thirty years on, the people who made it are the last ones who interviewed the people who were there.

casual

Mon Oct 19 · 5:30pm

AIIA Innovation Night: South Korea in NYC

NYU Stern, 44 W 4th St, Greenwich Village

Five Seoul startups, and the organizers have explicitly skipped the pitches and the panel in favor of live demos you can put your hands on and tell the founder what is wrong with. Free, Korean food, and the no-slides format is the whole reason to go.

professional

Thu Oct 22 · 6:00pm

AI Engineers: Devs & Drinks

Sugar Mouse, 47 3rd Ave, East Village

No panel, no fireside, no badge scan — a bar and the people who ship agents in daylight. The signal-to-theater ratio at these is usually better than at anything with a registration review.

professional

Sat Oct 24 · 5:30pm

ACE Presents: Rosemary's Baby, Q&A with Bobbie O'Steen

Metrograph, 7 Ludlow St, Lower East Side

The editors' guild brings in film-editing historian Bobbie O'Steen to take apart a film cut by Sam O'Steen, which is about as close to a primary source as a craft talk gets. The correct week of the year for it, and the paranoid-apartment-building genre has never been bettered.

casual

Quote of the day

“Type systems can show the absence of bugs, but not the presence of correctness.”

— Niko Matsakis

On this day

October 14 is the date the ground shifts. In 1066 Harold Godwinson's shield wall held the ridge at Senlac all day and then didn't, and England got a new owner by nightfall. In 1947, 881 years later to the day, Chuck Yeager flew the Bell X-1 past Mach 1 over the Mojave with two ribs taped up from a horse-riding accident he hadn't reported, and the sound barrier turned out to be a wall nobody had checked.

The puzzle corner

The Mini · Wordle · Connections

Two systems gave up on the general case today: Anthropic decided git's offline-first design was a tax it no longer pays, and D1 decided its control plane should never be in the query path at all. Both got faster by being less universal.