Mechanism◆Article

Setting UV_EXCLUDE_NEWER to a specific date makes uvx tool-name resolve to the most recent tool version available as of that date, and the cache can be busted and tools upgraded simply by bumping that date later.

The mechanism: pinning UV_EXCLUDE_NEWER fixes dependency resolution to a point-in-time snapshot, and bumping the date later is what triggers a cache-busting upgrade. ✦ AI generated

Simon Willison · Simon Willison's Weblog · 2026-07-14 · original ↗

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This means any uvx tool-name commands will resolve to the most recent version as-of that date, and you can bust the cache and upgrade the tools by bumping the date in the future.

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✳ uv ✳ UV_EXCLUDE_NEWER

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Context · 1

The goal of this recipe is to use Python tools in GitHub Actions without every workflow run hitting PyPI to download a fresh copy of the tool and its dependencies.Simon Willison · Simon Willison's Weblog · conf 70%

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The Python Package Index (PyPI) now rejects new files being uploaded to releases that are older than 14 days.Seth Larson · Simon Willison's Weblog · conf 85%

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explains mechanism → Setting a UV_EXCLUDE_NEWER environment variable to a fixed date and including that date in the GitHub Actions cache key produces a cache-friendly way to run uvx tool-name in workflows.Simon Willison · Simon Willison's Weblog