Keith Mancuso

some of what we've been designing in Claude Duet... a few big ideas, and some tiny details can't wait to see what you make with it join the waitlist: claude.com/product/claude-du…

Opus 5.5 is really good at making explainer animations "explain the story @pablofindsout uncovered about Kwahi Leonard in a 2d animation with a voice over."

I used Opus 5.5 to formally verify the Claude Agent SDK using Lean. A couple short prompts = 16 PRs fixing various bugs and race conditions. Video attached. TLA+ also works well. I sometimes combine Lean and TLA+ to look for issues around data flow, concurrency, and state mgmt. I don't know either language well, but Claude is excellent at both. This approach is super useful for formally modeling your code and finding bugs that a human probably wouldn't have spotted. Is formal verification the future of coding (or at least, bug finding)?

You can pop out any pane in the Claude Code desktop app into its own window. Drag the diff or terminal to a second screen while Claude keeps working in the main window, then dock it back whenever you want. You can also run sessions side-by-side or stacked.

Big one today — Tailwind is joining Shopify 🛍️

Trump: We could do tremendous good for ourselves by just not trading with countries.. We lose with Mexico $195 billion a year. They have nothing that we have to have, I mean. Hot tamales, tomatoes, a couple of things

i recently added this command to the claude-api skill. run it in Claude Code to fix common prompting "anti-patterns" that can hobble frontier models: /claude-api prompt-audit patterns include: 1/Verification rituals. Instructions like "double-check your work” or "verify twice before responding” are often taken literally by frontier models and can waste tokens. 2/ Thoroughness and emphasis boosters. "Be maximally thorough," "CRITICAL: YOU MUST ALWAYS…" can lead to verbosity and extra tool calls when working with frontier models. 3/ Mandatory procedures and scratchpad scaffolds. Fixed step processes (e.g., "think step by step in a scratchpad") or reasoning templates are rituals that frontier models don't need. This scaffolding can stack on top of native reasoning and use unnecessary tokens. 4/ Stale examples. Few-shot examples tuned to an older model's failure modes can teach a frontier model to imitate long reasoning chains on requests that don't need them. 5/ Contradictory rules. Frontier models are better at instruction following. Contradictory instructions ("always refund within policy" vs. "never issue refunds without escalation") can be followed more literally by frontier models, resulting in degraded performance. 6/ Dated configuration. Settings written for an older Claude generation (e.g., manual thinking budgets) can be rejected by the Claude Platform with newer models. these patterns accumulate in prompts over time, and can quietly degrade performance when upgrading to newer models. a common reason is the frontier models are better at instruction following, so these anti-patterns steer them to spend unnecessary tokens. example: i tested a migration from Opus 4.8 to Opus 5 on an internal customer support benchmark. with Opus 5 (and other frontier models like Fable 5.1), verification rituals ("verify twice") use unnecessary tokens by duplicating work. emphasis boosters ("be maximally thorough") become dozens of unneeded searches. applying prompt audits can improve performance and reduce cost (as shown in example attached and will be sharing a full write-up soon). also, the skill is also open source and some of this guidance likely applies generally across frontier models github.com/anthropics/skills… nitter.gq/petergyang/status/2094…