AI & Software
Two frontier launches in a day, and the price is the headline
Anthropic shipped Claude Opus 5.5 on 22 September: Fable-5.1-level on most tasks at 40% less, $4/$20 per million tokens (60% down on Opus 5), Terminal-Bench 4.0 up from 52.3% to 66.4%. OpenAI answered with GPT-6 Sol and Luna, cheaper siblings of Astra: Sol hits 68.8% on DeepSWE v1.1 at $2/$10; Luna manages 66.6% at $0.10/$0.50.
Both pitches are the same pitch — last quarter’s top-tier coding ability at a fraction of the cost. For agent loops that burn tokens on retries and test runs, that changes what’s worth automating more than any single benchmark does. (Vendor numbers; treat accordingly.)
Anthropic — Claude Opus 5.5 · OpenAI — GPT-6 Sol and Luna
AI & Software
A canary word showed Claude Code ignoring AGENTS.md
Claude Code’s AGENTS.md support sits behind a remotely-fetched feature flag that defaults to off. Set DISABLE_TELEMETRY=1 and the flag can’t be fetched — so a purely local file is silently skipped, no warning.
The detective method is the nice part: a directory containing only an AGENTS.md with a canary word in it, run under each telemetry setting, checking whether the canary surfaces. Workaround: a one-line CLAUDE.md containing @AGENTS.md. HN now tags it fixed.
szypowi.cz · Hacker News
Software
AI made Linear’s tests quadruple; CI had to learn to keep up
Test suites nearly 4× since January, yet PR wait time fell from over six minutes to just over five. The wins were unglamorous: tsgo cut typechecking 73%, pre-baked dependencies cut per-shard setup 44%, skipping checkout on jobs that don’t need it took 27 s to 7 s, and batching alone saved 87,000 runner-minutes a month.
The point generalises: when generating code gets cheap, verification becomes the constraint.
Linear
Embedded
An 1877 clock tower, run by a PIC16F628 nobody can explain
Volunteers from Action Porty climbed into the tower of Portobello Police Station in Edinburgh to get its clock going. The Victorian movement was the easy bit: lift a pawl, set the hands. The chimes come from an unmarked control box built around a ~2001 PIC16F628 with no clock of its own — it counts hours off a shaft-triggered switch, and you hold an “advance” button to step it.
Still unsolved: who designed the board, and what the status LED’s blink pattern means. Also, from inside the tower the hands appear to run backwards.
Point in the Cloud
Game Design
Divide by depth, and you have perspective
A clear walk through the projection matrix built up from one operation: divide x and y by z. Then each piece of the matrix gets a name — focal scale from field of view, aspect ratio, the two depth-mapping coefficients — and slots into world → view → clip → NDC → pixels.
For a balloon game where the camera and the horizon carry the whole mood, this is the place to start if you ever want a custom camera in Godot instead of stock Camera3D behaviour.
gabrieloc.com
Practice
100 digits of pi, designed so mistakes stay local
Back on HN (from 2024): Gregory Gundersen memorised pi with a Person-Action-Object system — each pair of digits maps to a person, action or object, and six digits make one scene placed in a memory palace. Building the 100-item code in Anki was the hard work; the digits then took about an hour.
The bit that fits your book: he chose the system for its error structure. A wrong recall is one mis-decoded glyph, isolated and easy to see, rather than a cascade that loses everything after it.
Gregory Gundersen — Engineering Memory
Chess
Uzbekistan 7 from 7, and they took China apart to do it
Round 7 in Samarkand: the hosts beat China 3–1, Abdusattorov over Ding Liren and Yakubboev over Yu Yangyi. Uzbekistan on 14 match points, with the Netherlands, India, Germany, Azerbaijan and Armenia all on 12.
Women: China and Kazakhstan drew 2–2, so there are no perfect scores left; they share the lead on 13 with five teams a point behind. Carissa Yip beat Kosteniuk on top board as the USA beat Switzerland. Four rounds left; the event ends 27 September.
Chess.com — Olympiad Round 7
Astronomy
A planet caught less than a million years after it formed
Elias 2-24 b, 454 light-years away in Ophiuchus, is the youngest exoplanet yet imaged directly: 1–4 Jupiter masses, about 55 AU out, sitting in a narrow gap that ALMA had already seen in the star’s dust disc. The team, led by Andrea Bernardi, used Keck’s NIRC2 vortex coronagraph, including archival 2018 data.
It’s a planet caught in the middle of carving its own gap, and the authors read it as evidence for core accretion.
Universe Today
Film Music
Howard Shore’s Fellowship, live, a short walk from Pyrmont
The Fellowship of the Ring in concert, marking its 25th anniversary: Shore’s complete score played live to picture by the Metropolitan Orchestra, Sydney Philharmonia Choirs and the Sydney Children’s Choir. Wednesday 7 and Thursday 8 October, 6:30pm, TikTok Entertainment Centre, Darling Harbour. Tickets from about $104.
It falls in the school holidays. Darling Harbour also has Naruto: The Symphonic Experience on 3 October.
Darling Harbour · TikTok Entertainment Centre
Sydney
Sunday evening, 7,500 runners come through Pyrmont
The Nike After Dark Half Marathon runs Sunday 27 September from Rozelle Parklands to Tumbalong Park, via White Bay, Glebe and Pyrmont. Harris Street, Pirrama Road and Bank Street close 4:30–9:45pm, route 389 is diverted, and the Anzac Bridge is managed 4:30–6:30pm.
Same day: Metro is down Chatswood–Sydenham for trackwork, several train lines run reduced timetables, and there’s the Panthers v Knights preliminary final at Accor Stadium (kick-off 4pm). The NRL Grand Final is there on Sunday 4 October.
Transport NSW — After Dark Half Marathon · Transport NSW events