0.12.3

Mailtrain-org/mailtrain0.12.3Aug 7, 2026by astral-automations-bot[bot]

AI Summary

This release adds support for CPython 3.13.15 and introduces a new `--output-format` flag for the `uv cache size` command. It also focuses on performance improvements, including reducing memory usage for large workspaces and lowering Linux startup latency.

Key Highlights

Added `--output-format` to select automatic, human-readable, or raw-byte output for `uv cache size`.
Reduced memory usage for large workspaces by streaming `uv workspace metadata` JSON output.
Reduced Linux startup latency by initializing the workspace cache before spawning another thread.
Avoided slow procfs reads during Python interpreter discovery on Linux.

New Features

New output format options for cache size command
Streaming workspace metadata for memory efficiency

Full Release Notes

## Release Notes

Released on 2026-08-07.

### Python

- Add CPython 3.13.15 ([#20997](https://github.com/astral-sh/uv/pull/20997))

### Preview features

- Add `--output-format` to select automatic, human-readable, or raw-byte output for `uv cache size` ([#20992](https://github.com/astral-sh/uv/pull/20992))
- Preserve JSON output from `uv workspace metadata --quiet` while suppressing diagnostics ([#20991](https://github.com/astral-sh/uv/pull/20991))
- Reduce memory usage for large workspaces by streaming `uv workspace metadata` JSON output ([#20990](https://github.com/astral-sh/uv/pull/20990))

### Performance

- Reduce Linux startup latency by initializing the workspace cache before spawning another thread ([#20989](https://github.com/astral-sh/uv/pull/20989))
- Reuse compiled workspace exclusion patterns during workspace discovery ([#20988](https://github.com/astral-sh/uv/pull/20988))
- Speed up conflict-heavy resolutions by avoiding materialized range complements ([#20982](https://github.com/astral-sh/uv/pull/20982))
- Avoid slow procfs reads during Python interpreter discovery on Linux ([#20987](https://github.com/astral-sh/uv/pull/20987))

### Documentation

- Add PEP 740 attestations to the GitHub Actions publishing example ([#20986](https://github.com/astral-sh/uv/pull/20986))
- Restrict the GitHub Actions publishing example to Python version tags ([#20973](https://github.com/astral-sh/uv/pull/20973))
- Correct `--python-pin` to `--pin-python` in the `uv init --bare` example ([#20876](https://github.com/astral-sh/uv/pull/20876))

## Install uv 0.12.3

### Install prebuilt binaries via shell script

```sh
curl --proto '=https' --tlsv1.2 -LsSf https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-installer.sh | sh
```

### Install prebuilt binaries via powershell script

```sh
powershell -ExecutionPolicy Bypass -c "irm https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-installer.ps1 | iex"
```

## Download uv 0.12.3

|  File  | Platform | Checksum |
|--------|----------|----------|
| [uv-aarch64-apple-darwin.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-aarch64-apple-darwin.tar.gz) | Apple Silicon macOS | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-aarch64-apple-darwin.tar.gz.sha256) |
| [uv-x86_64-apple-darwin.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-x86_64-apple-darwin.tar.gz) | Intel macOS | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-x86_64-apple-darwin.tar.gz.sha256) |
| [uv-aarch64-pc-windows-msvc.zip](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-aarch64-pc-windows-msvc.zip) | ARM64 Windows | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-aarch64-pc-windows-msvc.zip.sha256) |
| [uv-i686-pc-windows-msvc.zip](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-i686-pc-windows-msvc.zip) | x86 Windows | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-i686-pc-windows-msvc.zip.sha256) |
| [uv-x86_64-pc-windows-msvc.zip](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-x86_64-pc-windows-msvc.zip) | x64 Windows | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-x86_64-pc-windows-msvc.zip.sha256) |
| [uv-aarch64-unknown-linux-gnu.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-aarch64-unknown-linux-gnu.tar.gz) | ARM64 Linux | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-aarch64-unknown-linux-gnu.tar.gz.sha256) |
| [uv-i686-unknown-linux-gnu.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-i686-unknown-linux-gnu.tar.gz) | x86 Linux | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-i686-unknown-linux-gnu.tar.gz.sha256) |
| [uv-powerpc64le-unknown-linux-gnu.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-powerpc64le-unknown-linux-gnu.tar.gz) | PPC64LE Linux | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-powerpc64le-unknown-linux-gnu.tar.gz.sha256) |
| [uv-riscv64gc-unknown-linux-gnu.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-riscv64gc-unknown-linux-gnu.tar.gz) | RISCV Linux | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-riscv64gc-unknown-linux-gnu.tar.gz.sha256) |
| [uv-s390x-unknown-linux-gnu.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-s390x-unknown-linux-gnu.tar.gz) | S390x Linux | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-s390x-unknown-linux-gnu.tar.gz.sha256) |
| [uv-x86_64-unknown-linux-gnu.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-x86_64-unknown-linux-gnu.tar.gz) | x64 Linux | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-x86_64-unknown-linux-gnu.tar.gz.sha256) |
| [uv-armv7-unknown-linux-gnueabihf.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-armv7-unknown-linux-gnueabihf.tar.gz) | ARMv7 Linux | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-armv7-unknown-linux-gnueabihf.tar.gz.sha256) |
| [uv-aarch64-unknown-linux-musl.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-aarch64-unknown-linux-musl.tar.gz) | ARM64 MUSL Linux | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-aarch64-unknown-linux-musl.tar.gz.sha256) |
| [uv-i686-unknown-linux-musl.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-i686-unknown-linux-musl.tar.gz) | x86 MUSL Linux | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-i686-unknown-linux-musl.tar.gz.sha256) |
| [uv-riscv64gc-unknown-linux-musl.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-riscv64gc-unknown-linux-musl.tar.gz) | RISCV MUSL Linux | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-riscv64gc-unknown-linux-musl.tar.gz.sha256) |
| [uv-x86_64-unknown-linux-musl.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-x86_64-unknown-linux-musl.tar.gz) | x64 MUSL Linux | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-x86_64-unknown-linux-musl.tar.gz.sha256) |
| [uv-arm-unknown-linux-musleabihf.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-arm-unknown-linux-musleabihf.tar.gz) | ARMv6 MUSL Linux (Hardfloat) | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-arm-unknown-linux-musleabihf.tar.gz.sha256) |
| [uv-armv7-unknown-linux-musleabihf.tar.gz](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-armv7-unknown-linux-musleabihf.tar.gz) | ARMv7 MUSL Linux | [checksum](https://releases.astral.sh/github/uv/releases/download/0.12.3/uv-armv7-unknown-linux-musleabihf.tar.gz.sha256) |

## Verifying GitHub Artifact Attestations

The artifacts in this release have attestations generated with GitHub Artifact Attestations. These can be verified by using the [GitHub CLI](https://cli.github.com/manual/gh_attestation_verify):
```sh
gh attestation verify <file-path of downloaded artifact> --repo astral-sh/uv
```

You can also download the attestation from [GitHub](https://github.com/astral-sh/uv/attestations) and verify against that directly:
```sh
gh attestation verify <file-path of downloaded artifact> --bundle <file-path of downloaded attestation>
```