A morning paper for product designers
Today's thread

Model upgrades are outrunning our habits, not just our tools

Lenny's Newsletter reports a user returning to Claude after Opus 5.5 fixed verbosity and agentic weaknesses, while Sidebar's agent-files piece argues instructions from older model generations actively hurt performance if left unaudited. A new model release is only useful if you also revisit the scaffolding—prompts, agent files, workflows—you built around the old one.

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01Lenny's Newsletter40 d

Opus 5.5 brings Claude back cheaper, faster, less preachy—with real limits still

If you wrote off Claude for its hedging, this is a concrete signal that agentic and frontend prototyping behavior has changed enough to retest it.

Read on lennysnewsletter.com
Try today

Open one coding agent config file you haven't touched in a month and delete any instruction that no longer earns its place.

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