Speed up version client by partial response reads

chore: update known checksums for 0.10.10

Co-authored-by: eifinger <eifinger@users.noreply.github.com>

.agents/skills/dependabot-pr-rollup/SKILL.md

@@ -0,0 +1,48 @@
+---
+name: dependabot-pr-rollup
+description: Find open Dependabot PRs for the current GitHub repo, compare each PR head to its base branch, replay only the net dependency changes in a fresh worktree and branch, run npm validation, and optionally commit, push, and open a PR. Use when you want to batch or manually replicate active Dependabot updates.
+license: MIT
+compatibility: Requires git, git worktree, gh CLI auth, npm, and a GitHub repo with an origin remote.
+---
+
+# Dependabot PR Rollup
+
+## When to use
+
+Use this skill when the user wants to:
+- find all open Dependabot PRs in the current repo
+- reproduce their net effect in one local branch
+- validate the result with the repo's standard npm checks
+- optionally commit, push, and open a PR
+
+## Workflow
+
+1. Inspect the current checkout state, but do not reuse a dirty worktree.
+2. List open Dependabot PRs with `gh pr list --state open --author app/dependabot`.
+3. For each PR, collect the title, base branch, head branch, changed files, and relevant diffs.
+4. Compare each PR head against `origin/<base>` instead of trusting the PR title. Dependabot PRs can already be partially merged, superseded by newer versions, or have no remaining net effect.
+5. Create a new worktree and branch from `origin/<base>`.
+6. Reproduce only the remaining dependency changes in the new worktree.
+   - Inspect `package.json` before editing.
+   - Run `npm ci --ignore-scripts` before applying updates.
+   - Use `npm install ... --ignore-scripts` for direct dependency changes so `package-lock.json` stays in sync.
+7. Run `npm run all`.
+8. If requested, commit the changed source, lockfile, and generated artifacts, then push and open a PR.
+
+## Repo-specific notes
+
+- Use `gh` for GitHub operations.
+- Keep the user's original checkout untouched by working in a separate worktree.
+- In this repo, `npm run all` is the safest validation command because it runs build, check, package, and test.
+- If dependency changes affect bundled output, include the regenerated `dist/` files.
+
+## Report back
+
+Always report:
+- open Dependabot PRs found
+- which PRs required no net changes
+- new branch name
+- new worktree path
+- files changed
+- `npm run all` result
+- if applicable, commit SHA and PR URL

.github/copilot-instructions.md

@@ -1,263 +0,0 @@
-# Copilot Instructions for setup-uv
-
-This document provides essential information for GitHub Copilot coding agents working on the `astral-sh/setup-uv` repository.
-
-## Repository Overview
-
-**setup-uv** is a GitHub Action that sets up the [uv](https://docs.astral.sh/uv/)
-Python package installer in GitHub Actions workflows.
-It's a TypeScript-based action that downloads uv binaries, manages caching, handles version resolution,
-and configures the environment for subsequent workflow steps.
-
-### Key Features
-
-- Downloads and installs specific uv versions from GitHub releases
-- Supports version resolution from config files (pyproject.toml, uv.toml, .tool-versions)
-- Implements intelligent caching for both uv cache and Python installations
-- Provides cross-platform support (Linux, macOS, Windows, including ARM architectures)
-- Includes problem matchers for Python error reporting
-- Supports environment activation and custom tool directories
-
-## Repository Structure
-
-**Size**: Small-medium repository (~50 source files, ~400 total files including dependencies)
-**Languages**: TypeScript (primary), JavaScript (compiled output), JSON (configuration)
-**Runtime**: Node.js 24 (GitHub Actions runtime)
-**Key Dependencies**: @actions/core, @actions/cache, @actions/tool-cache, @octokit/core
-
-### Core Architecture
-
-```
-src/
-├── setup-uv.ts          # Main entry point and orchestration
-├── save-cache.ts        # Post-action cache saving logic
-├── update-known-versions.ts  # Maintenance script for version updates
-├── cache/               # Cache management functionality
-├── download/            # Version resolution and binary downloading
-├── utils/               # Input parsing, platform detection, configuration
-└── version/             # Version resolution from various file formats
-```
-
-### Key Files and Locations
-
-- **Action Definition**: `action.yml` - Defines all inputs/outputs and entry points
-- **Main Source**: `src/setup-uv.ts` - Primary action logic
-- **Configuration**: `biome.json` (linting), `tsconfig.json` (TypeScript), `jest.config.js` (testing)
-- **Compiled Output**: `dist/` - Contains compiled Node.js bundles (auto-generated, committed)
-- **Test Fixtures**: `__tests__/fixtures/` - Sample projects for different configuration scenarios
-- **Workflows**: `.github/workflows/test.yml` - Comprehensive CI/CD pipeline
-
-## Build and Development Process
-
-### Prerequisites
-
-- Node.js 24+ (matches GitHub Actions runtime)
-- npm (included with Node.js)
-
-### Essential Commands (ALWAYS run in this order)
-
-#### 1. Install Dependencies
-
-```bash
-npm ci --ignore-scripts
-```
-
-**Timing**: ~20-30 seconds
-**Note**: Always run this first after cloning or when package.json changes
-
-#### 2. Build TypeScript
-
-```bash
-npm run build
-```
-
-**Timing**: ~5-10 seconds
-**Purpose**: Compiles TypeScript source to JavaScript in `lib/` directory
-
-#### 3. Lint and Format Code
-
-```bash
-npm run check
-```
-
-**Timing**: ~2-5 seconds
-**Tool**: Biome (replaces ESLint/Prettier)
-**Auto-fixes**: Formatting, import organization, basic linting issues
-
-#### 4. Package for Distribution
-
-```bash
-npm run package
-```
-
-**Timing**: ~20-30 seconds
-**Purpose**: Creates bundled distributions in `dist/` using @vercel/ncc
-**Critical**: This step MUST be run before committing - the `dist/` files are used by GitHub Actions
-
-#### 5. Run Tests
-
-```bash
-npm test
-```
-
-**Timing**: ~10-15 seconds
-**Framework**: Jest with TypeScript support
-**Coverage**: Unit tests for version resolution, input parsing, checksum validation
-
-#### 6. Complete Validation (Recommended)
-
-```bash
-npm run all
-```
-
-**Timing**: ~60-90 seconds
-**Purpose**: Runs build → check → package → test in sequence
-**Use**: Before making pull requests or when unsure about build state
-
-### Important Build Notes
-
-**CRITICAL**: Always run `npm run package` after making code changes. The `dist/` directory contains the compiled bundles that GitHub Actions actually executes. Forgetting this step will cause your changes to have no effect.
-
-**TypeScript Warnings**: You may see ts-jest warnings about "isolatedModules" - these are harmless and don't affect functionality.
-
-**Biome**: This project uses Biome instead of ESLint/Prettier. Run `npm run check` to fix formatting and linting issues automatically.
-
-## Testing Strategy
-
-### Unit Tests
-
-- **Location**: `__tests__/` directory
-- **Framework**: Jest with ts-jest transformer
-- **Coverage**: Version resolution, input parsing, checksum validation, utility functions
-
-### Integration Tests
-
-- **Location**: `.github/workflows/test.yml`
-- **Scope**: Full end-to-end testing across multiple platforms and scenarios
-- **Key Test Categories**:
-  - Version installation (specific, latest, semver ranges)
-  - Cache behavior (setup, restore, invalidation)
-  - Cross-platform compatibility (Ubuntu, macOS, Windows, ARM)
-  - Configuration file parsing (pyproject.toml, uv.toml, requirements.txt)
-  - Error handling and edge cases
-
-### Test Fixtures
-
-Located in `__tests__/fixtures/`, these provide sample projects with different configurations:
-- `pyproject-toml-project/` - Standard Python project with uv version specification
-- `uv-toml-project/` - Project using uv.toml configuration
-- `requirements-txt-project/` - Legacy requirements.txt format
-- `cache-dir-defined-project/` - Custom cache directory configuration
-
-## Continuous Integration
-
-### GitHub Workflows
-
-#### Primary Test Suite (`.github/workflows/test.yml`)
-
-- **Triggers**: PRs, pushes to main, manual dispatch
-- **Matrix**: Multiple OS (Ubuntu, macOS, Windows), architecture (x64, ARM), and configuration combinations
-- **Duration**: ~5 minutes for full matrix
-- **Key Validations**:
-  - Cross-platform installation and functionality
-  - Cache behavior and performance
-  - Version resolution from various sources
-  - Tool directory configurations
-  - Problem matcher functionality
-
-#### Maintenance Workflows
-
-- **CodeQL Analysis**: Security scanning on pushes/PRs
-- **Update Known Versions**: Daily job to sync with latest uv releases
-- **Dependabot**: Automated dependency updates
-
-### Pre-commit Validation
-
-The CI runs these checks that you should run locally:
-1. `npm run all` - Complete build and test suite
-2. ActionLint - GitHub Actions workflow validation
-3. Change detection - Ensures no uncommitted build artifacts
-
-## Key Configuration Files
-
-### Action Configuration (`action.yml`)
-
-Defines 20+ inputs including version specifications,
-cache settings, tool directories, and environment options.
-This file is the authoritative source for understanding available action parameters.
-
-### TypeScript Configuration (`tsconfig.json`)
-
-- Target: ES2024
-- Module: nodenext (Node.js modules)
-- Strict mode enabled
-- Output directory: `lib/`
-
-### Linting Configuration (`biome.json`)
-
-- Formatter and linter combined
-- Enforces consistent code style
-- Automatically organizes imports and sorts object keys
-
-## Common Development Patterns
-
-### Making Code Changes
-
-1. Edit TypeScript source files in `src/`
-2. Run `npm run build` to compile
-3. Run `npm run check` to format and lint
-4. Run `npm run package` to update distribution bundles
-5. Run `npm test` to verify functionality
-6. Commit all changes including `dist/` files
-
-### Adding New Features
-
-- Follow existing patterns in `src/utils/inputs.ts` for new action inputs
-- Update `action.yml` to declare new inputs/outputs
-- Add corresponding tests in `__tests__/`
-- Add a test in `.github/workflows/test.yml` if it affects integration
-- Update README.md with usage examples
-
-### Cache-Related Changes
-
-- Cache logic is complex and affects performance significantly
-- Test with multiple cache scenarios (hit, miss, invalidation)
-- Consider impact on both GitHub-hosted and self-hosted runners
-- Validate cache key generation and dependency detection
-
-### Version Resolution Changes
-
-- Version resolution supports multiple file formats and precedence rules
-- Test with fixtures in `__tests__/fixtures/`
-- Consider backward compatibility with existing projects
-- Validate semver and PEP 440 specification handling
-
-## Troubleshooting
-
-### Build Failures
-
-- **"Module not found"**: Run `npm ci --ignore-scripts` to ensure dependencies are installed
-- **TypeScript errors**: Check `tsconfig.json` and ensure all imports are valid
-- **Test failures**: Check if test fixtures have been modified or if logic changes broke assumptions
-
-### Action Failures in Workflows
-
-- **Changes not taking effect**: Ensure `npm run package` was run and `dist/` files committed
-- **Version resolution issues**: Check version specification format and file existence
-- **Cache problems**: Verify cache key generation and dependency glob patterns
-
-### Common Gotchas
-
-- **Forgetting to package**: Code changes won't work without running `npm run package`
-- **Platform differences**: Windows paths use backslashes, test cross-platform behavior
-- **Cache invalidation**: Cache keys are sensitive to dependency file changes
-- **Tool directory permissions**: Some platforms require specific directory setups
-
-## Trust These Instructions
-
-These instructions are comprehensive and current. Only search for additional information if:
-- You encounter specific error messages not covered here
-- You need to understand implementation details of specific functions
-- The instructions appear outdated (check repository commit history)
-
-For most development tasks, following the build process and development patterns outlined above will be sufficient.

.github/release-drafter.yml

@@ -19,7 +19,7 @@ categories:
     labels:
       - "maintenance"
       - "ci"
-      - "update-known-versions"
+      - "update-known-checksums"
   - title: "📚 Documentation"
     labels:
       - "documentation"

.github/workflows/test.yml

@@ -38,7 +38,7 @@ jobs:
           npm run all
       - name: Check all jobs are in all-tests-passed.needs
         run: |
-          tsc check-all-tests-passed-needs.ts
+          tsc --module nodenext --moduleResolution nodenext --target es2022 check-all-tests-passed-needs.ts
           node check-all-tests-passed-needs.js
         working-directory: .github/scripts
       - name: Make sure no changes from linters are detected

.github/workflows/update-known-checksums.yml

@@ -1,4 +1,4 @@
-name: "Update known versions"
+name: "Update known checksums"
 on:
   workflow_dispatch:
   schedule:
@@ -20,14 +20,13 @@ jobs:
           persist-credentials: true
       - uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
         with:
-          node-version: "20"
-      - name: Update known versions
-        id: update-known-versions
+          node-version-file: .nvmrc
+          cache: npm
+      - name: Update known checksums
+        id: update-known-checksums
         run:
-          node dist/update-known-versions/index.js
+          node dist/update-known-checksums/index.cjs
           src/download/checksum/known-checksums.ts
-          version-manifest.json
-          ${{ secrets.GITHUB_TOKEN }}
       - name: Check for changes
         id: changes-exist
         run: |
@@ -48,10 +47,10 @@ jobs:
           git config user.name "$GITHUB_ACTOR"
           git config user.email "$GITHUB_ACTOR@users.noreply.github.com"
           git add .
-          git commit -m "chore: update known versions for $LATEST_VERSION"
+          git commit -m "chore: update known checksums for $LATEST_VERSION"
           git push origin HEAD:refs/heads/main
         env:
-          LATEST_VERSION: ${{ steps.update-known-versions.outputs.latest-version }}
+          LATEST_VERSION: ${{ steps.update-known-checksums.outputs.latest-version }}
 
       - name: Create Pull Request
         if: ${{ steps.changes-exist.outputs.changes-exist == 'true' && steps.commit-and-push.outcome != 'success' }}
@@ -60,11 +59,11 @@ jobs:
           commit-message: "chore: update known checksums"
           title:
             "chore: update known checksums for ${{
-            steps.update-known-versions.outputs.latest-version }}"
+            steps.update-known-checksums.outputs.latest-version }}"
           body:
             "chore: update known checksums for ${{
-            steps.update-known-versions.outputs.latest-version }}"
+            steps.update-known-checksums.outputs.latest-version }}"
           base: main
-          labels: "automated-pr,update-known-versions"
-          branch: update-known-versions-pr
+          labels: "automated-pr,update-known-checksums"
+          branch: update-known-checksums-pr
           delete-branch: true

AGENTS.md

@@ -1 +0,0 @@
-.github/copilot-instructions.md

AGENTS.md

@@ -0,0 +1,18 @@
+# setup-uv agent notes
+
+This repository is a TypeScript-based GitHub Action for installing `uv` in GitHub Actions workflows. It also supports restoring/saving the `uv` cache and optional managed-Python caching.
+
+- The published action runs the committed bundles in `dist/`, not the TypeScript in `src/`. After any code change, run `npm run package` and commit the resulting `dist/` updates.
+- Standard local validation is:
+  1. `npm ci --ignore-scripts`
+  2. `npm run all`
+- `npm run check` uses Biome (not ESLint/Prettier) and rewrites files in place.
+- User-facing changes are usually multi-file changes. If you add or change inputs, outputs, or behavior, update `action.yml`, the implementation in `src/`, tests in `__tests__/`, relevant docs/README, and then re-package.
+- The easiest areas to regress are version resolution and caching. When touching them, add or update tests for precedence, cache invalidation, and cross-platform path behavior.
+- Workflow edits have extra CI-only checks (`actionlint` and `zizmor`); `npm run all` does not cover them.
+- Source is authored with bundler-friendly TypeScript, but published action artifacts in `dist/` are bundled as CommonJS for maximum GitHub Actions runtime compatibility with `@actions/*` dependencies.
+- Keep these concerns separate when changing module formats:
+  - `src/` and tests may use modern ESM-friendly TypeScript patterns.
+  - `dist/` should prioritize runtime reliability over format purity.
+  - Do not switch published bundles to ESM without validating the actual committed artifacts under the target Node runtime.
+- Before finishing, make sure validation does not leave generated or formatting-only diffs behind.

README.md

@@ -68,7 +68,7 @@ Have a look under [Advanced Configuration](#advanced-configuration) for detailed
     # The checksum of the uv version to install
     checksum: ""
 
-    # Used to increase the rate limit when retrieving versions and downloading uv
+    # Used when downloading uv from GitHub releases
     github-token: ${{ github.token }}
 
     # Enable uploading of the uv cache: true, false, or auto (enabled on GitHub-hosted runners, disabled on self-hosted runners)
@@ -114,7 +114,7 @@ Have a look under [Advanced Configuration](#advanced-configuration) for detailed
     # Custom path to set UV_TOOL_BIN_DIR to
     tool-bin-dir: ""
 
-    # URL to the manifest file containing available versions and download URLs
+    # URL to a custom manifest file (NDJSON preferred, legacy JSON array is deprecated)
     manifest-file: ""
 
     # Add problem matchers
@@ -190,10 +190,12 @@ For more advanced configuration options, see our detailed documentation:
 
 ## How it works
 
-This action downloads uv from the uv repo's official
-[GitHub Releases](https://github.com/astral-sh/uv) and uses the
-[GitHub Actions Toolkit](https://github.com/actions/toolkit) to cache it as a tool to speed up
-consecutive runs on self-hosted runners.
+By default, this action resolves uv versions from
+[`astral-sh/versions`](https://github.com/astral-sh/versions) (NDJSON) and downloads uv from the
+official [GitHub Releases](https://github.com/astral-sh/uv).
+
+It then uses the [GitHub Actions Toolkit](https://github.com/actions/toolkit) to cache uv as a
+tool to speed up consecutive runs on self-hosted runners.
 
 The installed version of uv is then added to the runner PATH, enabling later steps to invoke it
 by name (`uv`).

__tests__/download/checksum/checksum.test.ts

@@ -4,10 +4,11 @@ import {
   validateChecksum,
 } from "../../../src/download/checksum/checksum";
 
-test("checksum should match", async () => {
-  const validChecksum =
+const validChecksum =
   "f3da96ec7e995debee7f5d52ecd034dfb7074309a1da42f76429ecb814d813a3";
-  const filePath = "__tests__/fixtures/checksumfile";
+const filePath = "__tests__/fixtures/checksumfile";
+
+test("checksum should match", async () => {
   // string params don't matter only test the checksum mechanism, not known checksums
   await validateChecksum(
     validChecksum,
@@ -18,6 +19,16 @@ test("checksum should match", async () => {
   );
 });
 
+test("provided checksum beats known checksums", async () => {
+  await validateChecksum(
+    validChecksum,
+    filePath,
+    "x86_64",
+    "unknown-linux-gnu",
+    "0.3.0",
+  );
+});
+
 type KnownVersionFixture = { version: string; known: boolean };
 
 it.each<KnownVersionFixture>([

__tests__/download/download-version.test.ts

@@ -0,0 +1,271 @@
+import { beforeEach, describe, expect, it, jest } from "@jest/globals";
+import * as semver from "semver";
+
+const mockInfo = jest.fn();
+const mockWarning = jest.fn();
+
+jest.unstable_mockModule("@actions/core", () => ({
+  debug: jest.fn(),
+  info: mockInfo,
+  warning: mockWarning,
+}));
+
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockDownloadTool = jest.fn<any>();
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockExtractTar = jest.fn<any>();
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockExtractZip = jest.fn<any>();
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockCacheDir = jest.fn<any>();
+
+jest.unstable_mockModule("@actions/tool-cache", () => ({
+  cacheDir: mockCacheDir,
+  downloadTool: mockDownloadTool,
+  evaluateVersions: (versions: string[], range: string) =>
+    semver.maxSatisfying(versions, range) ?? "",
+  extractTar: mockExtractTar,
+  extractZip: mockExtractZip,
+  find: () => "",
+  findAllVersions: () => [],
+  isExplicitVersion: (version: string) => semver.valid(version) !== null,
+}));
+
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockGetLatestVersionFromNdjson = jest.fn<any>();
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockGetAllVersionsFromNdjson = jest.fn<any>();
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockGetArtifactFromNdjson = jest.fn<any>();
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockGetHighestSatisfyingVersionFromNdjson = jest.fn<any>();
+
+jest.unstable_mockModule("../../src/download/versions-client", () => ({
+  getAllVersions: mockGetAllVersionsFromNdjson,
+  getArtifact: mockGetArtifactFromNdjson,
+  getHighestSatisfyingVersion: mockGetHighestSatisfyingVersionFromNdjson,
+  getLatestVersion: mockGetLatestVersionFromNdjson,
+}));
+
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockGetAllManifestVersions = jest.fn<any>();
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockGetLatestVersionInManifest = jest.fn<any>();
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockGetManifestArtifact = jest.fn<any>();
+
+jest.unstable_mockModule("../../src/download/version-manifest", () => ({
+  getAllVersions: mockGetAllManifestVersions,
+  getLatestKnownVersion: mockGetLatestVersionInManifest,
+  getManifestArtifact: mockGetManifestArtifact,
+}));
+
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockValidateChecksum = jest.fn<any>();
+
+jest.unstable_mockModule("../../src/download/checksum/checksum", () => ({
+  validateChecksum: mockValidateChecksum,
+}));
+
+const {
+  downloadVersionFromManifest,
+  downloadVersionFromNdjson,
+  resolveVersion,
+} = await import("../../src/download/download-version");
+
+describe("download-version", () => {
+  beforeEach(() => {
+    mockInfo.mockReset();
+    mockWarning.mockReset();
+    mockDownloadTool.mockReset();
+    mockExtractTar.mockReset();
+    mockExtractZip.mockReset();
+    mockCacheDir.mockReset();
+    mockGetLatestVersionFromNdjson.mockReset();
+    mockGetAllVersionsFromNdjson.mockReset();
+    mockGetArtifactFromNdjson.mockReset();
+    mockGetHighestSatisfyingVersionFromNdjson.mockReset();
+    mockGetAllManifestVersions.mockReset();
+    mockGetLatestVersionInManifest.mockReset();
+    mockGetManifestArtifact.mockReset();
+    mockValidateChecksum.mockReset();
+
+    mockDownloadTool.mockResolvedValue("/tmp/downloaded");
+    mockExtractTar.mockResolvedValue("/tmp/extracted");
+    mockExtractZip.mockResolvedValue("/tmp/extracted");
+    mockCacheDir.mockResolvedValue("/tmp/cached");
+  });
+
+  describe("resolveVersion", () => {
+    it("uses astral-sh/versions to resolve latest", async () => {
+      mockGetLatestVersionFromNdjson.mockResolvedValue("0.9.26");
+
+      const version = await resolveVersion("latest", undefined);
+
+      expect(version).toBe("0.9.26");
+      expect(mockGetLatestVersionFromNdjson).toHaveBeenCalledTimes(1);
+    });
+
+    it("streams astral-sh/versions to resolve the highest matching version", async () => {
+      mockGetHighestSatisfyingVersionFromNdjson.mockResolvedValue("0.9.26");
+
+      const version = await resolveVersion("^0.9.0", undefined);
+
+      expect(version).toBe("0.9.26");
+      expect(mockGetHighestSatisfyingVersionFromNdjson).toHaveBeenCalledWith(
+        "^0.9.0",
+      );
+      expect(mockGetAllVersionsFromNdjson).not.toHaveBeenCalled();
+    });
+
+    it("still loads all versions when resolving the lowest matching version", async () => {
+      mockGetAllVersionsFromNdjson.mockResolvedValue(["0.9.26", "0.9.25"]);
+
+      const version = await resolveVersion("^0.9.0", undefined, "lowest");
+
+      expect(version).toBe("0.9.25");
+      expect(mockGetAllVersionsFromNdjson).toHaveBeenCalledTimes(1);
+      expect(mockGetHighestSatisfyingVersionFromNdjson).not.toHaveBeenCalled();
+    });
+
+    it("does not fall back when astral-sh/versions fails", async () => {
+      mockGetLatestVersionFromNdjson.mockRejectedValue(
+        new Error("NDJSON unavailable"),
+      );
+
+      await expect(resolveVersion("latest", undefined)).rejects.toThrow(
+        "NDJSON unavailable",
+      );
+    });
+
+    it("uses manifest-file when provided", async () => {
+      mockGetAllManifestVersions.mockResolvedValue(["0.9.26", "0.9.25"]);
+
+      const version = await resolveVersion(
+        "^0.9.0",
+        "https://example.com/custom.ndjson",
+      );
+
+      expect(version).toBe("0.9.26");
+      expect(mockGetAllManifestVersions).toHaveBeenCalledWith(
+        "https://example.com/custom.ndjson",
+      );
+    });
+  });
+
+  describe("downloadVersionFromNdjson", () => {
+    it("fails when NDJSON metadata lookup fails", async () => {
+      mockGetArtifactFromNdjson.mockRejectedValue(
+        new Error("NDJSON unavailable"),
+      );
+
+      await expect(
+        downloadVersionFromNdjson(
+          "unknown-linux-gnu",
+          "x86_64",
+          "0.9.26",
+          undefined,
+          "token",
+        ),
+      ).rejects.toThrow("NDJSON unavailable");
+
+      expect(mockDownloadTool).not.toHaveBeenCalled();
+      expect(mockValidateChecksum).not.toHaveBeenCalled();
+    });
+
+    it("fails when no matching artifact exists in NDJSON metadata", async () => {
+      mockGetArtifactFromNdjson.mockResolvedValue(undefined);
+
+      await expect(
+        downloadVersionFromNdjson(
+          "unknown-linux-gnu",
+          "x86_64",
+          "0.9.26",
+          undefined,
+          "token",
+        ),
+      ).rejects.toThrow(
+        "Could not find artifact for version 0.9.26, arch x86_64, platform unknown-linux-gnu in https://raw.githubusercontent.com/astral-sh/versions/main/v1/uv.ndjson .",
+      );
+
+      expect(mockDownloadTool).not.toHaveBeenCalled();
+      expect(mockValidateChecksum).not.toHaveBeenCalled();
+    });
+
+    it("uses built-in checksums for default NDJSON downloads", async () => {
+      mockGetArtifactFromNdjson.mockResolvedValue({
+        archiveFormat: "tar.gz",
+        sha256: "ndjson-checksum-that-should-be-ignored",
+        url: "https://example.com/uv.tar.gz",
+      });
+
+      await downloadVersionFromNdjson(
+        "unknown-linux-gnu",
+        "x86_64",
+        "0.9.26",
+        undefined,
+        "token",
+      );
+
+      expect(mockValidateChecksum).toHaveBeenCalledWith(
+        undefined,
+        "/tmp/downloaded",
+        "x86_64",
+        "unknown-linux-gnu",
+        "0.9.26",
+      );
+    });
+  });
+
+  describe("downloadVersionFromManifest", () => {
+    it("uses manifest-file checksum metadata when checksum input is unset", async () => {
+      mockGetManifestArtifact.mockResolvedValue({
+        archiveFormat: "tar.gz",
+        checksum: "manifest-checksum",
+        downloadUrl: "https://example.com/custom-uv.tar.gz",
+      });
+
+      await downloadVersionFromManifest(
+        "https://example.com/custom.ndjson",
+        "unknown-linux-gnu",
+        "x86_64",
+        "0.9.26",
+        "",
+        "token",
+      );
+
+      expect(mockValidateChecksum).toHaveBeenCalledWith(
+        "manifest-checksum",
+        "/tmp/downloaded",
+        "x86_64",
+        "unknown-linux-gnu",
+        "0.9.26",
+      );
+    });
+
+    it("prefers checksum input over manifest-file checksum metadata", async () => {
+      mockGetManifestArtifact.mockResolvedValue({
+        archiveFormat: "tar.gz",
+        checksum: "manifest-checksum",
+        downloadUrl: "https://example.com/custom-uv.tar.gz",
+      });
+
+      await downloadVersionFromManifest(
+        "https://example.com/custom.ndjson",
+        "unknown-linux-gnu",
+        "x86_64",
+        "0.9.26",
+        "user-checksum",
+        "token",
+      );
+
+      expect(mockValidateChecksum).toHaveBeenCalledWith(
+        "user-checksum",
+        "/tmp/downloaded",
+        "x86_64",
+        "unknown-linux-gnu",
+        "0.9.26",
+      );
+    });
+  });
+});

__tests__/download/version-manifest.test.ts

@@ -0,0 +1,136 @@
+import { beforeEach, describe, expect, it, jest } from "@jest/globals";
+
+const mockWarning = jest.fn();
+
+jest.unstable_mockModule("@actions/core", () => ({
+  debug: jest.fn(),
+  info: jest.fn(),
+  warning: mockWarning,
+}));
+
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockFetch = jest.fn<any>();
+jest.unstable_mockModule("../../src/utils/fetch", () => ({
+  fetch: mockFetch,
+}));
+
+const {
+  clearManifestCache,
+  getAllVersions,
+  getLatestKnownVersion,
+  getManifestArtifact,
+} = await import("../../src/download/version-manifest");
+
+const legacyManifestResponse = JSON.stringify([
+  {
+    arch: "x86_64",
+    artifactName: "uv-x86_64-unknown-linux-gnu.tar.gz",
+    downloadUrl:
+      "https://example.com/releases/download/0.7.12-alpha.1/uv-x86_64-unknown-linux-gnu.tar.gz",
+    platform: "unknown-linux-gnu",
+    version: "0.7.12-alpha.1",
+  },
+  {
+    arch: "x86_64",
+    artifactName: "uv-x86_64-unknown-linux-gnu.tar.gz",
+    downloadUrl:
+      "https://example.com/releases/download/0.7.13/uv-x86_64-unknown-linux-gnu.tar.gz",
+    platform: "unknown-linux-gnu",
+    version: "0.7.13",
+  },
+]);
+
+const ndjsonManifestResponse = `{"version":"0.10.0","artifacts":[{"platform":"x86_64-unknown-linux-gnu","variant":"default","url":"https://example.com/releases/download/0.10.0/uv-x86_64-unknown-linux-gnu.tar.gz","archive_format":"tar.gz","sha256":"checksum-100"}]}
+{"version":"0.9.30","artifacts":[{"platform":"x86_64-unknown-linux-gnu","variant":"default","url":"https://example.com/releases/download/0.9.30/uv-x86_64-unknown-linux-gnu.tar.gz","archive_format":"tar.gz","sha256":"checksum-0930"}]}`;
+
+const multiVariantManifestResponse = `{"version":"0.10.0","artifacts":[{"platform":"x86_64-unknown-linux-gnu","variant":"managed-python","url":"https://example.com/releases/download/0.10.0/uv-x86_64-unknown-linux-gnu-managed-python.tar.gz","archive_format":"tar.gz","sha256":"checksum-managed"},{"platform":"x86_64-unknown-linux-gnu","variant":"default","url":"https://example.com/releases/download/0.10.0/uv-x86_64-unknown-linux-gnu-default.zip","archive_format":"zip","sha256":"checksum-default"}]}`;
+
+function createMockResponse(
+  ok: boolean,
+  status: number,
+  statusText: string,
+  data: string,
+) {
+  return {
+    ok,
+    status,
+    statusText,
+    text: async () => data,
+  };
+}
+
+describe("version-manifest", () => {
+  beforeEach(() => {
+    clearManifestCache();
+    mockFetch.mockReset();
+    mockWarning.mockReset();
+  });
+
+  it("supports the legacy JSON manifest format", async () => {
+    mockFetch.mockResolvedValue(
+      createMockResponse(true, 200, "OK", legacyManifestResponse),
+    );
+
+    const latest = await getLatestKnownVersion(
+      "https://example.com/legacy.json",
+    );
+    const artifact = await getManifestArtifact(
+      "https://example.com/legacy.json",
+      "0.7.13",
+      "x86_64",
+      "unknown-linux-gnu",
+    );
+
+    expect(latest).toBe("0.7.13");
+    expect(artifact).toEqual({
+      archiveFormat: undefined,
+      checksum: undefined,
+      downloadUrl:
+        "https://example.com/releases/download/0.7.13/uv-x86_64-unknown-linux-gnu.tar.gz",
+    });
+    expect(mockWarning).toHaveBeenCalledTimes(1);
+  });
+
+  it("supports NDJSON manifests", async () => {
+    mockFetch.mockResolvedValue(
+      createMockResponse(true, 200, "OK", ndjsonManifestResponse),
+    );
+
+    const versions = await getAllVersions("https://example.com/custom.ndjson");
+    const artifact = await getManifestArtifact(
+      "https://example.com/custom.ndjson",
+      "0.10.0",
+      "x86_64",
+      "unknown-linux-gnu",
+    );
+
+    expect(versions).toEqual(["0.10.0", "0.9.30"]);
+    expect(artifact).toEqual({
+      archiveFormat: "tar.gz",
+      checksum: "checksum-100",
+      downloadUrl:
+        "https://example.com/releases/download/0.10.0/uv-x86_64-unknown-linux-gnu.tar.gz",
+    });
+    expect(mockWarning).not.toHaveBeenCalled();
+  });
+
+  it("prefers the default variant when a manifest contains multiple variants", async () => {
+    mockFetch.mockResolvedValue(
+      createMockResponse(true, 200, "OK", multiVariantManifestResponse),
+    );
+
+    const artifact = await getManifestArtifact(
+      "https://example.com/multi-variant.ndjson",
+      "0.10.0",
+      "x86_64",
+      "unknown-linux-gnu",
+    );
+
+    expect(artifact).toEqual({
+      archiveFormat: "zip",
+      checksum: "checksum-default",
+      downloadUrl:
+        "https://example.com/releases/download/0.10.0/uv-x86_64-unknown-linux-gnu-default.zip",
+    });
+  });
+});

__tests__/download/versions-client.test.ts

@@ -0,0 +1,241 @@
+import { beforeEach, describe, expect, it, jest } from "@jest/globals";
+
+// biome-ignore lint/suspicious/noExplicitAny: Mock requires flexible typing in tests.
+const mockFetch = jest.fn<any>();
+
+jest.unstable_mockModule("../../src/utils/fetch", () => ({
+  fetch: mockFetch,
+}));
+
+const {
+  clearCache,
+  fetchVersionData,
+  getAllVersions,
+  getArtifact,
+  getHighestSatisfyingVersion,
+  getLatestVersion,
+  parseVersionData,
+} = await import("../../src/download/versions-client");
+
+const sampleNdjsonResponse = `{"version":"0.9.26","artifacts":[{"platform":"aarch64-apple-darwin","variant":"default","url":"https://github.com/astral-sh/uv/releases/download/0.9.26/uv-aarch64-apple-darwin.tar.gz","archive_format":"tar.gz","sha256":"fcf0a9ea6599c6ae28a4c854ac6da76f2c889354d7c36ce136ef071f7ab9721f"},{"platform":"x86_64-pc-windows-msvc","variant":"default","url":"https://github.com/astral-sh/uv/releases/download/0.9.26/uv-x86_64-pc-windows-msvc.zip","archive_format":"zip","sha256":"eb02fd95d8e0eed462b4a67ecdd320d865b38c560bffcda9a0b87ec944bdf036"}]}
+{"version":"0.9.25","artifacts":[{"platform":"aarch64-apple-darwin","variant":"default","url":"https://github.com/astral-sh/uv/releases/download/0.9.25/uv-aarch64-apple-darwin.tar.gz","archive_format":"tar.gz","sha256":"606b3c6949d971709f2526fa0d9f0fd23ccf60e09f117999b406b424af18a6a6"}]}`;
+
+const multiVariantNdjsonResponse = `{"version":"0.9.26","artifacts":[{"platform":"aarch64-apple-darwin","variant":"python-managed","url":"https://github.com/astral-sh/uv/releases/download/0.9.26/uv-aarch64-apple-darwin-managed.tar.gz","archive_format":"tar.gz","sha256":"managed-checksum"},{"platform":"aarch64-apple-darwin","variant":"default","url":"https://github.com/astral-sh/uv/releases/download/0.9.26/uv-aarch64-apple-darwin.zip","archive_format":"zip","sha256":"default-checksum"}]}`;
+
+function createMockStream(chunks: string[]): ReadableStream<Uint8Array> {
+  const encoder = new TextEncoder();
+
+  return new ReadableStream<Uint8Array>({
+    start(controller) {
+      for (const chunk of chunks) {
+        controller.enqueue(encoder.encode(chunk));
+      }
+      controller.close();
+    },
+  });
+}
+
+function createMockResponse(
+  ok: boolean,
+  status: number,
+  statusText: string,
+  data: string,
+  chunks: string[] = [data],
+) {
+  return {
+    body: createMockStream(chunks),
+    ok,
+    status,
+    statusText,
+    text: async () => data,
+  };
+}
+
+describe("versions-client", () => {
+  beforeEach(() => {
+    clearCache();
+    mockFetch.mockReset();
+  });
+
+  describe("fetchVersionData", () => {
+    it("should fetch and parse NDJSON data", async () => {
+      mockFetch.mockResolvedValue(
+        createMockResponse(true, 200, "OK", sampleNdjsonResponse),
+      );
+
+      const versions = await fetchVersionData();
+
+      expect(versions).toHaveLength(2);
+      expect(versions[0].version).toBe("0.9.26");
+      expect(versions[1].version).toBe("0.9.25");
+    });
+
+    it("should throw error on failed fetch", async () => {
+      mockFetch.mockResolvedValue(
+        createMockResponse(false, 500, "Internal Server Error", ""),
+      );
+
+      await expect(fetchVersionData()).rejects.toThrow(
+        "Failed to fetch version data: 500 Internal Server Error",
+      );
+    });
+
+    it("should cache results", async () => {
+      mockFetch.mockResolvedValue(
+        createMockResponse(true, 200, "OK", sampleNdjsonResponse),
+      );
+
+      await fetchVersionData();
+      await fetchVersionData();
+
+      expect(mockFetch).toHaveBeenCalledTimes(1);
+    });
+  });
+
+  describe("getLatestVersion", () => {
+    it("should return the first version (newest)", async () => {
+      mockFetch.mockResolvedValue(
+        createMockResponse(true, 200, "OK", sampleNdjsonResponse),
+      );
+
+      const latest = await getLatestVersion();
+
+      expect(latest).toBe("0.9.26");
+    });
+
+    it("should stop after the first record when resolving latest", async () => {
+      mockFetch.mockResolvedValue(
+        createMockResponse(
+          true,
+          200,
+          "OK",
+          `${sampleNdjsonResponse}\n{"version":`,
+          [`${sampleNdjsonResponse.split("\n")[0]}\n`, '{"version":'],
+        ),
+      );
+
+      const latest = await getLatestVersion();
+
+      expect(latest).toBe("0.9.26");
+    });
+  });
+
+  describe("getAllVersions", () => {
+    it("should return all version strings", async () => {
+      mockFetch.mockResolvedValue(
+        createMockResponse(true, 200, "OK", sampleNdjsonResponse),
+      );
+
+      const versions = await getAllVersions();
+
+      expect(versions).toEqual(["0.9.26", "0.9.25"]);
+    });
+  });
+
+  describe("getHighestSatisfyingVersion", () => {
+    it("should return the first matching version from the stream", async () => {
+      mockFetch.mockResolvedValue(
+        createMockResponse(
+          true,
+          200,
+          "OK",
+          `${sampleNdjsonResponse}\n{"version":`,
+          [`${sampleNdjsonResponse.split("\n")[0]}\n`, '{"version":'],
+        ),
+      );
+
+      const version = await getHighestSatisfyingVersion("^0.9.0");
+
+      expect(version).toBe("0.9.26");
+    });
+  });
+
+  describe("getArtifact", () => {
+    beforeEach(() => {
+      mockFetch.mockResolvedValue(
+        createMockResponse(true, 200, "OK", sampleNdjsonResponse),
+      );
+    });
+
+    it("should find artifact by version and platform", async () => {
+      const artifact = await getArtifact("0.9.26", "aarch64", "apple-darwin");
+
+      expect(artifact).toEqual({
+        archiveFormat: "tar.gz",
+        sha256:
+          "fcf0a9ea6599c6ae28a4c854ac6da76f2c889354d7c36ce136ef071f7ab9721f",
+        url: "https://github.com/astral-sh/uv/releases/download/0.9.26/uv-aarch64-apple-darwin.tar.gz",
+      });
+    });
+
+    it("should stop once the requested version is found", async () => {
+      mockFetch.mockResolvedValue(
+        createMockResponse(
+          true,
+          200,
+          "OK",
+          `${sampleNdjsonResponse}\n{"version":`,
+          [`${sampleNdjsonResponse.split("\n")[0]}\n`, '{"version":'],
+        ),
+      );
+
+      const artifact = await getArtifact("0.9.26", "aarch64", "apple-darwin");
+
+      expect(artifact).toEqual({
+        archiveFormat: "tar.gz",
+        sha256:
+          "fcf0a9ea6599c6ae28a4c854ac6da76f2c889354d7c36ce136ef071f7ab9721f",
+        url: "https://github.com/astral-sh/uv/releases/download/0.9.26/uv-aarch64-apple-darwin.tar.gz",
+      });
+    });
+
+    it("should find windows artifact", async () => {
+      const artifact = await getArtifact("0.9.26", "x86_64", "pc-windows-msvc");
+
+      expect(artifact).toEqual({
+        archiveFormat: "zip",
+        sha256:
+          "eb02fd95d8e0eed462b4a67ecdd320d865b38c560bffcda9a0b87ec944bdf036",
+        url: "https://github.com/astral-sh/uv/releases/download/0.9.26/uv-x86_64-pc-windows-msvc.zip",
+      });
+    });
+
+    it("should prefer the default variant when multiple artifacts share a platform", async () => {
+      mockFetch.mockResolvedValue(
+        createMockResponse(true, 200, "OK", multiVariantNdjsonResponse),
+      );
+
+      const artifact = await getArtifact("0.9.26", "aarch64", "apple-darwin");
+
+      expect(artifact).toEqual({
+        archiveFormat: "zip",
+        sha256: "default-checksum",
+        url: "https://github.com/astral-sh/uv/releases/download/0.9.26/uv-aarch64-apple-darwin.zip",
+      });
+    });
+
+    it("should return undefined for unknown version", async () => {
+      const artifact = await getArtifact("0.0.1", "aarch64", "apple-darwin");
+
+      expect(artifact).toBeUndefined();
+    });
+
+    it("should return undefined for unknown platform", async () => {
+      const artifact = await getArtifact(
+        "0.9.26",
+        "aarch64",
+        "unknown-linux-musl",
+      );
+
+      expect(artifact).toBeUndefined();
+    });
+  });
+
+  describe("parseVersionData", () => {
+    it("should throw for malformed NDJSON", () => {
+      expect(() =>
+        parseVersionData('{"version":"0.1.0"', "test-source"),
+      ).toThrow("Failed to parse version data from test-source");
+    });
+  });
+});

__tests__/utils/inputs.test.ts

@@ -1,14 +1,3 @@
-jest.mock("@actions/core", () => {
-  return {
-    debug: jest.fn(),
-    getBooleanInput: jest.fn(
-      (name: string) => (mockInputs[name] ?? "") === "true",
-    ),
-    getInput: jest.fn((name: string) => mockInputs[name] ?? ""),
-    warning: jest.fn(),
-  };
-});
-
 import {
   afterEach,
   beforeEach,
@@ -22,6 +11,26 @@ import {
 let mockInputs: Record<string, string> = {};
 const ORIGINAL_HOME = process.env.HOME;
 
+const mockDebug = jest.fn();
+const mockGetBooleanInput = jest.fn(
+  (name: string) => (mockInputs[name] ?? "") === "true",
+);
+const mockGetInput = jest.fn((name: string) => mockInputs[name] ?? "");
+const mockInfo = jest.fn();
+const mockWarning = jest.fn();
+
+jest.unstable_mockModule("@actions/core", () => ({
+  debug: mockDebug,
+  getBooleanInput: mockGetBooleanInput,
+  getInput: mockGetInput,
+  info: mockInfo,
+  warning: mockWarning,
+}));
+
+async function importInputsModule() {
+  return await import("../../src/utils/inputs");
+}
+
 describe("cacheDependencyGlob", () => {
   beforeEach(() => {
     jest.resetModules();
@@ -36,21 +45,21 @@ describe("cacheDependencyGlob", () => {
 
   it("returns empty string when input not provided", async () => {
     mockInputs["working-directory"] = "/workspace";
-    const { cacheDependencyGlob } = await import("../../src/utils/inputs");
+    const { cacheDependencyGlob } = await importInputsModule();
     expect(cacheDependencyGlob).toBe("");
   });
 
   it("resolves a single relative path", async () => {
     mockInputs["working-directory"] = "/workspace";
     mockInputs["cache-dependency-glob"] = "requirements.txt";
-    const { cacheDependencyGlob } = await import("../../src/utils/inputs");
+    const { cacheDependencyGlob } = await importInputsModule();
     expect(cacheDependencyGlob).toBe("/workspace/requirements.txt");
   });
 
   it("strips leading ./ from relative path", async () => {
     mockInputs["working-directory"] = "/workspace";
     mockInputs["cache-dependency-glob"] = "./uv.lock";
-    const { cacheDependencyGlob } = await import("../../src/utils/inputs");
+    const { cacheDependencyGlob } = await importInputsModule();
     expect(cacheDependencyGlob).toBe("/workspace/uv.lock");
   });
 
@@ -58,7 +67,7 @@ describe("cacheDependencyGlob", () => {
     mockInputs["working-directory"] = "/workspace";
     mockInputs["cache-dependency-glob"] =
       "  ~/.cache/file1\n ./rel/file2  \nfile3.txt";
-    const { cacheDependencyGlob } = await import("../../src/utils/inputs");
+    const { cacheDependencyGlob } = await importInputsModule();
     expect(cacheDependencyGlob).toBe(
       [
         "/home/testuser/.cache/file1", // expanded tilde, absolute path unchanged
@@ -71,7 +80,7 @@ describe("cacheDependencyGlob", () => {
   it("keeps absolute path unchanged in multiline input", async () => {
     mockInputs["working-directory"] = "/workspace";
     mockInputs["cache-dependency-glob"] = "/abs/path.lock\nrelative.lock";
-    const { cacheDependencyGlob } = await import("../../src/utils/inputs");
+    const { cacheDependencyGlob } = await importInputsModule();
     expect(cacheDependencyGlob).toBe(
       ["/abs/path.lock", "/workspace/relative.lock"].join("\n"),
     );
@@ -80,7 +89,7 @@ describe("cacheDependencyGlob", () => {
   it("handles exclusions in relative paths correct", async () => {
     mockInputs["working-directory"] = "/workspace";
     mockInputs["cache-dependency-glob"] = "!/abs/path.lock\n!relative.lock";
-    const { cacheDependencyGlob } = await import("../../src/utils/inputs");
+    const { cacheDependencyGlob } = await importInputsModule();
     expect(cacheDependencyGlob).toBe(
       ["!/abs/path.lock", "!/workspace/relative.lock"].join("\n"),
     );
@@ -104,7 +113,7 @@ describe("tool directories", () => {
     mockInputs["tool-bin-dir"] = "~/tool-bin-dir";
     mockInputs["tool-dir"] = "~/tool-dir";
 
-    const { toolBinDir, toolDir } = await import("../../src/utils/inputs");
+    const { toolBinDir, toolDir } = await importInputsModule();
 
     expect(toolBinDir).toBe("/home/testuser/tool-bin-dir");
     expect(toolDir).toBe("/home/testuser/tool-dir");
@@ -127,9 +136,7 @@ describe("cacheLocalPath", () => {
     mockInputs["working-directory"] = "/workspace";
     mockInputs["cache-local-path"] = "~/uv-cache/cache-local-path";
 
-    const { CacheLocalSource, cacheLocalPath } = await import(
-      "../../src/utils/inputs"
-    );
+    const { CacheLocalSource, cacheLocalPath } = await importInputsModule();
 
     expect(cacheLocalPath).toEqual({
       path: "/home/testuser/uv-cache/cache-local-path",
@@ -152,7 +159,7 @@ describe("venvPath", () => {
 
   it("defaults to .venv in the working directory", async () => {
     mockInputs["working-directory"] = "/workspace";
-    const { venvPath } = await import("../../src/utils/inputs");
+    const { venvPath } = await importInputsModule();
     expect(venvPath).toBe("/workspace/.venv");
   });
 
@@ -160,7 +167,7 @@ describe("venvPath", () => {
     mockInputs["working-directory"] = "/workspace";
     mockInputs["activate-environment"] = "true";
     mockInputs["venv-path"] = "custom-venv";
-    const { venvPath } = await import("../../src/utils/inputs");
+    const { venvPath } = await importInputsModule();
     expect(venvPath).toBe("/workspace/custom-venv");
   });
 
@@ -168,7 +175,7 @@ describe("venvPath", () => {
     mockInputs["working-directory"] = "/workspace";
     mockInputs["activate-environment"] = "true";
     mockInputs["venv-path"] = "custom-venv/";
-    const { venvPath } = await import("../../src/utils/inputs");
+    const { venvPath } = await importInputsModule();
     expect(venvPath).toBe("/workspace/custom-venv");
   });
 
@@ -176,7 +183,7 @@ describe("venvPath", () => {
     mockInputs["working-directory"] = "/workspace";
     mockInputs["activate-environment"] = "true";
     mockInputs["venv-path"] = "/tmp/custom-venv";
-    const { venvPath } = await import("../../src/utils/inputs");
+    const { venvPath } = await importInputsModule();
     expect(venvPath).toBe("/tmp/custom-venv");
   });
 
@@ -184,7 +191,7 @@ describe("venvPath", () => {
     mockInputs["working-directory"] = "/workspace";
     mockInputs["activate-environment"] = "true";
     mockInputs["venv-path"] = "~/.venv";
-    const { venvPath } = await import("../../src/utils/inputs");
+    const { venvPath } = await importInputsModule();
     expect(venvPath).toBe("/home/testuser/.venv");
   });
 
@@ -192,18 +199,11 @@ describe("venvPath", () => {
     mockInputs["working-directory"] = "/workspace";
     mockInputs["venv-path"] = "custom-venv";
 
-    const { activateEnvironment, venvPath } = await import(
-      "../../src/utils/inputs"
-    );
+    const { activateEnvironment, venvPath } = await importInputsModule();
 
     expect(activateEnvironment).toBe(false);
     expect(venvPath).toBe("/workspace/custom-venv");
-
-    const mockedCore = jest.requireMock("@actions/core") as {
-      warning: jest.Mock;
-    };
-
-    expect(mockedCore.warning).toHaveBeenCalledWith(
+    expect(mockWarning).toHaveBeenCalledWith(
       "venv-path is only used when activate-environment is true",
     );
   });

__tests__/version/tool-versions-file.test.ts

@@ -1,113 +1,121 @@
-jest.mock("node:fs");
-jest.mock("@actions/core", () => ({
-  warning: jest.fn(),
+import { beforeEach, describe, expect, it, jest } from "@jest/globals";
+
+const mockReadFileSync = jest.fn();
+const mockWarning = jest.fn();
+
+jest.unstable_mockModule("node:fs", () => ({
+  default: {
+    readFileSync: mockReadFileSync,
+  },
 }));
 
-import fs from "node:fs";
-import * as core from "@actions/core";
-import { beforeEach, describe, expect, it, jest } from "@jest/globals";
-import { getUvVersionFromToolVersions } from "../../src/version/tool-versions-file";
+jest.unstable_mockModule("@actions/core", () => ({
+  warning: mockWarning,
+}));
 
-const mockedFs = fs as jest.Mocked<typeof fs>;
-const mockedCore = core as jest.Mocked<typeof core>;
+async function getVersionFromToolVersions(filePath: string) {
+  const { getUvVersionFromToolVersions } = await import(
+    "../../src/version/tool-versions-file"
+  );
+
+  return getUvVersionFromToolVersions(filePath);
+}
 
 describe("getUvVersionFromToolVersions", () => {
   beforeEach(() => {
+    jest.resetModules();
     jest.clearAllMocks();
   });
 
-  it("should return undefined for non-.tool-versions files", () => {
-    const result = getUvVersionFromToolVersions("package.json");
+  it("should return undefined for non-.tool-versions files", async () => {
+    const result = await getVersionFromToolVersions("package.json");
     expect(result).toBeUndefined();
-    expect(mockedFs.readFileSync).not.toHaveBeenCalled();
+    expect(mockReadFileSync).not.toHaveBeenCalled();
   });
 
-  it("should return version for valid uv entry", () => {
+  it("should return version for valid uv entry", async () => {
     const fileContent = "python 3.11.0\nuv 0.1.0\nnodejs 18.0.0";
-    mockedFs.readFileSync.mockReturnValue(fileContent);
+    mockReadFileSync.mockReturnValue(fileContent);
 
-    const result = getUvVersionFromToolVersions(".tool-versions");
+    const result = await getVersionFromToolVersions(".tool-versions");
 
     expect(result).toBe("0.1.0");
-    expect(mockedFs.readFileSync).toHaveBeenCalledWith(
-      ".tool-versions",
-      "utf8",
-    );
+    expect(mockReadFileSync).toHaveBeenCalledWith(".tool-versions", "utf8");
   });
 
-  it("should return version for uv entry with v prefix", () => {
+  it("should return version for uv entry with v prefix", async () => {
     const fileContent = "uv v0.2.0";
-    mockedFs.readFileSync.mockReturnValue(fileContent);
+    mockReadFileSync.mockReturnValue(fileContent);
 
-    const result = getUvVersionFromToolVersions(".tool-versions");
+    const result = await getVersionFromToolVersions(".tool-versions");
 
     expect(result).toBe("0.2.0");
   });
 
-  it("should handle whitespace around uv entry", () => {
+  it("should handle whitespace around uv entry", async () => {
     const fileContent = "  uv   0.3.0  ";
-    mockedFs.readFileSync.mockReturnValue(fileContent);
+    mockReadFileSync.mockReturnValue(fileContent);
 
-    const result = getUvVersionFromToolVersions(".tool-versions");
+    const result = await getVersionFromToolVersions(".tool-versions");
 
     expect(result).toBe("0.3.0");
   });
 
-  it("should skip commented lines", () => {
+  it("should skip commented lines", async () => {
     const fileContent = "# uv 0.1.0\npython 3.11.0\nuv 0.2.0";
-    mockedFs.readFileSync.mockReturnValue(fileContent);
+    mockReadFileSync.mockReturnValue(fileContent);
 
-    const result = getUvVersionFromToolVersions(".tool-versions");
+    const result = await getVersionFromToolVersions(".tool-versions");
 
     expect(result).toBe("0.2.0");
   });
 
-  it("should return first matching uv version", () => {
+  it("should return first matching uv version", async () => {
     const fileContent = "uv 0.1.0\npython 3.11.0\nuv 0.2.0";
-    mockedFs.readFileSync.mockReturnValue(fileContent);
+    mockReadFileSync.mockReturnValue(fileContent);
 
-    const result = getUvVersionFromToolVersions(".tool-versions");
+    const result = await getVersionFromToolVersions(".tool-versions");
 
     expect(result).toBe("0.1.0");
   });
 
-  it("should return undefined when no uv entry found", () => {
+  it("should return undefined when no uv entry found", async () => {
     const fileContent = "python 3.11.0\nnodejs 18.0.0";
-    mockedFs.readFileSync.mockReturnValue(fileContent);
+    mockReadFileSync.mockReturnValue(fileContent);
 
-    const result = getUvVersionFromToolVersions(".tool-versions");
+    const result = await getVersionFromToolVersions(".tool-versions");
 
     expect(result).toBeUndefined();
   });
 
-  it("should return undefined for empty file", () => {
-    mockedFs.readFileSync.mockReturnValue("");
+  it("should return undefined for empty file", async () => {
+    mockReadFileSync.mockReturnValue("");
 
-    const result = getUvVersionFromToolVersions(".tool-versions");
+    const result = await getVersionFromToolVersions(".tool-versions");
 
     expect(result).toBeUndefined();
   });
 
-  it("should warn and return undefined for ref syntax", () => {
+  it("should warn and return undefined for ref syntax", async () => {
     const fileContent = "uv ref:main";
-    mockedFs.readFileSync.mockReturnValue(fileContent);
+    mockReadFileSync.mockReturnValue(fileContent);
 
-    const result = getUvVersionFromToolVersions(".tool-versions");
+    const result = await getVersionFromToolVersions(".tool-versions");
 
     expect(result).toBeUndefined();
-    expect(mockedCore.warning).toHaveBeenCalledWith(
+    expect(mockWarning).toHaveBeenCalledWith(
       "The ref syntax of .tool-versions is not supported. Please use a released version instead.",
     );
   });
 
-  it("should handle file path with .tool-versions extension", () => {
+  it("should handle file path with .tool-versions extension", async () => {
     const fileContent = "uv 0.1.0";
-    mockedFs.readFileSync.mockReturnValue(fileContent);
+    mockReadFileSync.mockReturnValue(fileContent);
 
-    const result = getUvVersionFromToolVersions("path/to/.tool-versions");
+    const result = await getVersionFromToolVersions("path/to/.tool-versions");
 
     expect(result).toBe("0.1.0");
-    expect(mockedFs.readFileSync).toHaveBeenCalledWith(
+    expect(mockReadFileSync).toHaveBeenCalledWith(
       "path/to/.tool-versions",
       "utf8",
     );

action.yml

@@ -26,7 +26,7 @@ inputs:
     required: false
   github-token:
     description:
-      "Used to increase the rate limit when retrieving versions and downloading uv."
+      "Used when downloading uv from GitHub releases."
     required: false
     default: ${{ github.token }}
   enable-cache:
@@ -75,7 +75,7 @@ inputs:
     description: "Custom path to set UV_TOOL_BIN_DIR to."
     required: false
   manifest-file:
-    description: "URL to the manifest file containing available versions and download URLs."
+    description: "URL to a custom manifest file. Supports the astral-sh/versions NDJSON format and the legacy JSON array format (deprecated)."
     required: false
   add-problem-matchers:
     description: "Add problem matchers."
@@ -102,8 +102,8 @@ outputs:
     description: "A boolean value to indicate the Python cache entry was found"
 runs:
   using: "node24"
-  main: "dist/setup/index.js"
-  post: "dist/save-cache/index.js"
+  main: "dist/setup/index.cjs"
+  post: "dist/save-cache/index.cjs"
   post-if: success()
 branding:
   icon: "package"

biome.json

@@ -1,5 +1,5 @@
 {
-  "$schema": "https://biomejs.dev/schemas/2.3.7/schema.json",
+  "$schema": "https://biomejs.dev/schemas/2.4.7/schema.json",
   "assist": {
     "actions": {
       "source": {

docs/customization.md

@@ -18,12 +18,29 @@ are automatically verified by this action. The sha256 hashes can be found on the
 
 ## Manifest file
 
-The `manifest-file` input allows you to specify a JSON manifest that lists available uv versions,
-architectures, and their download URLs. By default, this action uses the manifest file contained
-in this repository, which is automatically updated with each release of uv.
+By default, setup-uv reads version metadata from
+[`astral-sh/versions`](https://github.com/astral-sh/versions) (NDJSON format).
 
-The manifest file contains an array of objects, each describing a version,
-architecture, platform, and the corresponding download URL. For example:
+The `manifest-file` input lets you override that source with your own URL, for example to test
+custom uv builds or alternate download locations.
+
+### Format
+
+The manifest file must be in NDJSON format, where each line is a JSON object representing a version and its artifacts. For example:
+
+```json
+{"version":"0.10.7","artifacts":[{"platform":"x86_64-unknown-linux-gnu","variant":"default","url":"https://example.com/uv-x86_64-unknown-linux-gnu.tar.gz","archive_format":"tar.gz","sha256":"..."}]}
+{"version":"0.10.6","artifacts":[{"platform":"x86_64-unknown-linux-gnu","variant":"default","url":"https://example.com/uv-x86_64-unknown-linux-gnu.tar.gz","archive_format":"tar.gz","sha256":"..."}]}
+```
+
+setup-uv currently only supports `default` as the `variant`.
+
+The `archive_format` field is currently ignored.
+
+### Legacy format: JSON array (deprecated)
+
+The previous JSON array format is still supported for compatibility, but deprecated and will be
+removed in a future major release.
 
 ```json
 [
@@ -33,26 +50,20 @@ architecture, platform, and the corresponding download URL. For example:
     "arch": "aarch64",
     "platform": "apple-darwin",
     "downloadUrl": "https://github.com/astral-sh/uv/releases/download/0.7.13/uv-aarch64-apple-darwin.tar.gz"
-  },
-  ...
+  }
 ]
 ```
 
-You can supply a custom manifest file URL to define additional versions,
-architectures, or different download URLs.
-This is useful if you maintain your own uv builds or want to override the default sources.
-
 ```yaml
 - name: Use a custom manifest file
   uses: astral-sh/setup-uv@v7
   with:
-    manifest-file: "https://example.com/my-custom-manifest.json"
+    manifest-file: "https://example.com/my-custom-manifest.ndjson"
 ```
 
 > [!NOTE]
-> When you use a custom manifest file and do not set the `version` input, its default value is `latest`.
-> This means the action will install the latest version available in the custom manifest file.
-> This is different from the default behavior of installing the latest version from the official uv releases.
+> When you use a custom manifest file and do not set the `version` input, setup-uv installs the
+> latest version from that custom manifest.
 
 ## Add problem matchers
 

docs/environment-and-tools.md

@@ -38,9 +38,12 @@ You can customize the venv location with `venv-path`, for example to place it in
 
 ## GitHub authentication token
 
-This action uses the GitHub API to fetch the uv release artifacts. To avoid hitting the GitHub API
-rate limit too quickly, an authentication token can be provided via the `github-token` input. By
-default, the `GITHUB_TOKEN` secret is used, which is automatically provided by GitHub Actions.
+By default, this action resolves available uv versions from
+[`astral-sh/versions`](https://github.com/astral-sh/versions), then downloads uv artifacts from
+GitHub Releases.
+
+You can provide a token via `github-token` to authenticate those downloads. By default, the
+`GITHUB_TOKEN` secret is used, which is automatically provided by GitHub Actions.
 
 If the default
 [permissions for the GitHub token](https://docs.github.com/en/actions/security-for-github-actions/security-guides/automatic-token-authentication#permissions-for-the-github_token)

jest.config.js

@@ -1,9 +0,0 @@
-module.exports = {
-  clearMocks: true,
-  moduleFileExtensions: ["js", "ts"],
-  testMatch: ["**/*.test.ts"],
-  transform: {
-    "^.+\\.ts$": "ts-jest",
-  },
-  verbose: true,
-};

jest.config.mjs

@@ -0,0 +1,14 @@
+import { createDefaultEsmPreset } from "ts-jest";
+
+const esmPreset = createDefaultEsmPreset({
+  tsconfig: "./tsconfig.json",
+});
+
+export default {
+  ...esmPreset,
+  clearMocks: true,
+  moduleFileExtensions: ["js", "mjs", "ts"],
+  testEnvironment: "node",
+  testMatch: ["**/*.test.ts"],
+  verbose: true,
+};

package.json

@@ -2,16 +2,19 @@
   "name": "setup-uv",
   "version": "1.0.0",
   "private": true,
+  "type": "module",
   "description": "Set up your GitHub Actions workflow with a specific version of uv",
-  "main": "dist/index.js",
+  "main": "dist/setup/index.cjs",
   "scripts": {
-    "build": "tsc",
+    "build": "tsc --noEmit",
     "check": "biome check --write",
-    "package": "ncc build -o dist/setup src/setup-uv.ts && ncc build -o dist/save-cache src/save-cache.ts && ncc build -o dist/update-known-versions src/update-known-versions.ts",
-    "test": "jest",
+    "package": "node scripts/build-dist.mjs",
+    "bench:versions": "node scripts/bench-versions-client.mjs",
+    "test:unit": "node --experimental-vm-modules ./node_modules/jest/bin/jest.js",
+    "test": "npm run build && npm run test:unit",
     "act": "act pull_request -W .github/workflows/test.yml --container-architecture linux/amd64 -s GITHUB_TOKEN=\"$(gh auth token)\"",
-    "update-known-versions": "RUNNER_TEMP=known_versions node dist/update-known-versions/index.js src/download/checksum/known-versions.ts \"$(gh auth token)\"",
-    "all": "npm run build && npm run check && npm run package && npm test"
+    "update-known-checksums": "RUNNER_TEMP=known_versions node dist/update-known-checksums/index.cjs src/download/checksum/known-checksums.ts",
+    "all": "npm run build && npm run check && npm run package && npm run test:unit"
   },
   "repository": {
     "type": "git",
@@ -26,28 +29,26 @@
   "author": "@eifinger",
   "license": "MIT",
   "dependencies": {
-    "@actions/cache": "^4.1.0",
-    "@actions/core": "^1.11.1",
-    "@actions/exec": "^1.1.1",
-    "@actions/glob": "^0.5.0",
-    "@actions/io": "^1.1.3",
-    "@actions/tool-cache": "^2.0.2",
-    "@octokit/core": "^7.0.6",
-    "@octokit/plugin-paginate-rest": "^14.0.0",
-    "@octokit/plugin-rest-endpoint-methods": "^17.0.0",
-    "@renovatebot/pep440": "^4.2.1",
+    "@actions/cache": "^6.0.0",
+    "@actions/core": "^3.0.0",
+    "@actions/exec": "^3.0.0",
+    "@actions/glob": "^0.6.1",
+    "@actions/io": "^3.0.2",
+    "@actions/tool-cache": "^4.0.0",
+    "@renovatebot/pep440": "^4.2.2",
     "smol-toml": "^1.6.0",
-    "undici": "5.28.5"
+    "undici": "^7.24.2"
   },
   "devDependencies": {
-    "@biomejs/biome": "2.3.8",
+    "@biomejs/biome": "^2.4.7",
     "@types/js-yaml": "^4.0.9",
-    "@types/node": "^24.10.1",
+    "@types/node": "^25.5.0",
     "@types/semver": "^7.7.1",
     "@vercel/ncc": "^0.38.4",
-    "jest": "^30.2.0",
-    "js-yaml": "^4.1.0",
-    "ts-jest": "^29.4.5",
+    "esbuild": "^0.27.4",
+    "jest": "^30.3.0",
+    "js-yaml": "^4.1.1",
+    "ts-jest": "^29.4.6",
     "typescript": "^5.9.3"
   }
 }

scripts/bench-versions-client.mjs

@@ -0,0 +1,483 @@
+import { performance } from "node:perf_hooks";
+import * as pep440 from "@renovatebot/pep440";
+import * as semver from "semver";
+import { ProxyAgent, fetch as undiciFetch } from "undici";
+
+const DEFAULT_URL =
+  "https://raw.githubusercontent.com/astral-sh/versions/main/v1/uv.ndjson";
+const DEFAULT_ITERATIONS = 100;
+const DEFAULT_ARCH = "aarch64";
+const DEFAULT_PLATFORM = "apple-darwin";
+
+function getProxyAgent() {
+  const httpProxy = process.env.HTTP_PROXY || process.env.http_proxy;
+  if (httpProxy) {
+    return new ProxyAgent(httpProxy);
+  }
+
+  const httpsProxy = process.env.HTTPS_PROXY || process.env.https_proxy;
+  if (httpsProxy) {
+    return new ProxyAgent(httpsProxy);
+  }
+
+  return undefined;
+}
+
+async function fetch(url) {
+  return await undiciFetch(url, {
+    dispatcher: getProxyAgent(),
+  });
+}
+
+function parseArgs(argv) {
+  const options = {
+    arch: DEFAULT_ARCH,
+    iterations: DEFAULT_ITERATIONS,
+    platform: DEFAULT_PLATFORM,
+    url: DEFAULT_URL,
+  };
+
+  for (let index = 0; index < argv.length; index += 1) {
+    const arg = argv[index];
+    const next = argv[index + 1];
+
+    if (arg === "--iterations" && next !== undefined) {
+      options.iterations = Number.parseInt(next, 10);
+      index += 1;
+      continue;
+    }
+
+    if (arg === "--url" && next !== undefined) {
+      options.url = next;
+      index += 1;
+      continue;
+    }
+
+    if (arg === "--arch" && next !== undefined) {
+      options.arch = next;
+      index += 1;
+      continue;
+    }
+
+    if (arg === "--platform" && next !== undefined) {
+      options.platform = next;
+      index += 1;
+    }
+  }
+
+  if (!Number.isInteger(options.iterations) || options.iterations <= 0) {
+    throw new Error("--iterations must be a positive integer");
+  }
+
+  return options;
+}
+
+function parseVersionLine(line, sourceDescription, lineNumber) {
+  let parsed;
+  try {
+    parsed = JSON.parse(line);
+  } catch (error) {
+    throw new Error(
+      `Failed to parse version data from ${sourceDescription} at line ${lineNumber}: ${error.message}`,
+    );
+  }
+
+  if (
+    typeof parsed !== "object" ||
+    parsed === null ||
+    typeof parsed.version !== "string" ||
+    !Array.isArray(parsed.artifacts)
+  ) {
+    throw new Error(
+      `Invalid NDJSON record in ${sourceDescription} at line ${lineNumber}.`,
+    );
+  }
+
+  return parsed;
+}
+
+function parseVersionData(data, sourceDescription) {
+  const versions = [];
+
+  for (const [index, line] of data.split("\n").entries()) {
+    const trimmed = line.trim();
+    if (trimmed === "") {
+      continue;
+    }
+
+    versions.push(parseVersionLine(trimmed, sourceDescription, index + 1));
+  }
+
+  if (versions.length === 0) {
+    throw new Error(`No version data found in ${sourceDescription}.`);
+  }
+
+  return versions;
+}
+
+async function readEntireResponse(response) {
+  if (response.body === null) {
+    const text = await response.text();
+    return {
+      bytesRead: Buffer.byteLength(text, "utf8"),
+      text,
+    };
+  }
+
+  const reader = response.body.getReader();
+  const decoder = new TextDecoder();
+  const chunks = [];
+  let bytesRead = 0;
+
+  while (true) {
+    const { done, value } = await reader.read();
+    if (done) {
+      chunks.push(decoder.decode());
+      break;
+    }
+
+    bytesRead += value.byteLength;
+    chunks.push(decoder.decode(value, { stream: true }));
+  }
+
+  return {
+    bytesRead,
+    text: chunks.join(""),
+  };
+}
+
+async function fetchAllVersions(url) {
+  const response = await fetch(url);
+  if (!response.ok) {
+    throw new Error(
+      `Failed to fetch version data: ${response.status} ${response.statusText}`,
+    );
+  }
+
+  const { bytesRead, text } = await readEntireResponse(response);
+  return {
+    bytesRead,
+    versions: parseVersionData(text, url),
+  };
+}
+
+async function streamUntil(url, predicate) {
+  const response = await fetch(url);
+  if (!response.ok) {
+    throw new Error(
+      `Failed to fetch version data: ${response.status} ${response.statusText}`,
+    );
+  }
+
+  if (response.body === null) {
+    const { bytesRead, versions } = await fetchAllVersions(url);
+    return {
+      bytesRead,
+      matchedVersion: versions.find(predicate),
+    };
+  }
+
+  const reader = response.body.getReader();
+  const decoder = new TextDecoder();
+  let bytesRead = 0;
+  let buffer = "";
+  let lineNumber = 0;
+
+  while (true) {
+    const { done, value } = await reader.read();
+    if (done) {
+      buffer += decoder.decode();
+      break;
+    }
+
+    bytesRead += value.byteLength;
+    buffer += decoder.decode(value, { stream: true });
+
+    let newlineIndex = buffer.indexOf("\n");
+    while (newlineIndex !== -1) {
+      const line = buffer.slice(0, newlineIndex);
+      buffer = buffer.slice(newlineIndex + 1);
+      const trimmed = line.trim();
+
+      if (trimmed !== "") {
+        lineNumber += 1;
+        const versionData = parseVersionLine(trimmed, url, lineNumber);
+        if (predicate(versionData)) {
+          await reader.cancel();
+          return { bytesRead, matchedVersion: versionData };
+        }
+      }
+
+      newlineIndex = buffer.indexOf("\n");
+    }
+  }
+
+  if (buffer.trim() !== "") {
+    lineNumber += 1;
+    const versionData = parseVersionLine(buffer.trim(), url, lineNumber);
+    if (predicate(versionData)) {
+      return { bytesRead, matchedVersion: versionData };
+    }
+  }
+
+  return { bytesRead, matchedVersion: undefined };
+}
+
+function versionSatisfies(version, versionSpecifier) {
+  return (
+    semver.satisfies(version, versionSpecifier) ||
+    pep440.satisfies(version, versionSpecifier)
+  );
+}
+
+function maxSatisfying(versions, versionSpecifier) {
+  const semverMatch = semver.maxSatisfying(versions, versionSpecifier);
+  if (semverMatch !== null) {
+    return semverMatch;
+  }
+
+  return pep440.maxSatisfying(versions, versionSpecifier) ?? undefined;
+}
+
+function selectArtifact(artifacts) {
+  if (artifacts.length === 1) {
+    return artifacts[0];
+  }
+
+  const defaultVariant = artifacts.find(
+    (candidate) => candidate.variant === "default",
+  );
+  if (defaultVariant !== undefined) {
+    return defaultVariant;
+  }
+
+  return artifacts[0];
+}
+
+async function benchmarkCase(name, expected, implementations, iterations) {
+  const results = {
+    name,
+    new: [],
+    old: [],
+  };
+
+  for (let iteration = 0; iteration < iterations; iteration += 1) {
+    const order = iteration % 2 === 0 ? ["old", "new"] : ["new", "old"];
+
+    for (const label of order) {
+      const implementation = implementations[label];
+      const startedAt = performance.now();
+      const outcome = await implementation.run();
+      const durationMs = performance.now() - startedAt;
+
+      if (outcome.value !== expected) {
+        throw new Error(
+          `${name} ${label} produced ${JSON.stringify(outcome.value)}; expected ${JSON.stringify(expected)}`,
+        );
+      }
+
+      results[label].push({
+        bytesRead: outcome.bytesRead,
+        durationMs,
+      });
+    }
+  }
+
+  return results;
+}
+
+function summarize(samples) {
+  const durations = samples
+    .map((sample) => sample.durationMs)
+    .sort((left, right) => left - right);
+  const bytes = samples
+    .map((sample) => sample.bytesRead)
+    .sort((left, right) => left - right);
+
+  const sum = (values) => values.reduce((total, value) => total + value, 0);
+  const percentile = (values, ratio) => {
+    const index = Math.min(
+      values.length - 1,
+      Math.max(0, Math.ceil(values.length * ratio) - 1),
+    );
+    return values[index];
+  };
+
+  return {
+    avgBytes: sum(bytes) / bytes.length,
+    avgMs: sum(durations) / durations.length,
+    maxMs: durations[durations.length - 1],
+    medianMs: percentile(durations, 0.5),
+    minMs: durations[0],
+    p95Ms: percentile(durations, 0.95),
+  };
+}
+
+function formatNumber(value, digits = 2) {
+  return value.toFixed(digits);
+}
+
+function formatSummary(name, oldSummary, newSummary) {
+  const speedup = oldSummary.avgMs / newSummary.avgMs;
+  const timeReduction =
+    ((oldSummary.avgMs - newSummary.avgMs) / oldSummary.avgMs) * 100;
+  const byteReduction =
+    ((oldSummary.avgBytes - newSummary.avgBytes) / oldSummary.avgBytes) * 100;
+
+  return [
+    `Scenario: ${name}`,
+    `  old avg: ${formatNumber(oldSummary.avgMs)} ms | median: ${formatNumber(oldSummary.medianMs)} ms | p95: ${formatNumber(oldSummary.p95Ms)} ms | avg bytes: ${Math.round(oldSummary.avgBytes)}`,
+    `  new avg: ${formatNumber(newSummary.avgMs)} ms | median: ${formatNumber(newSummary.medianMs)} ms | p95: ${formatNumber(newSummary.p95Ms)} ms | avg bytes: ${Math.round(newSummary.avgBytes)}`,
+    `  delta: ${formatNumber(timeReduction)}% faster | ${formatNumber(speedup)}x speedup | ${formatNumber(byteReduction)}% fewer bytes read`,
+  ].join("\n");
+}
+
+async function main() {
+  const options = parseArgs(process.argv.slice(2));
+  console.log(`Preparing benchmark data from ${options.url}`);
+  const baseline = await fetchAllVersions(options.url);
+  const latestVersion = baseline.versions[0]?.version;
+  if (!latestVersion) {
+    throw new Error("No versions found in NDJSON data");
+  }
+
+  const latestArtifact = selectArtifact(
+    baseline.versions[0].artifacts.filter(
+      (candidate) =>
+        candidate.platform === `${options.arch}-${options.platform}`,
+    ),
+  );
+  if (!latestArtifact) {
+    throw new Error(
+      `No artifact found for ${options.arch}-${options.platform} in ${latestVersion}`,
+    );
+  }
+
+  const rangeSpecifier = `^${latestVersion.split(".")[0]}.${latestVersion.split(".")[1]}.0`;
+
+  console.log(
+    `Running ${options.iterations} iterations per scenario against ${options.url}`,
+  );
+  console.log(`Latest version: ${latestVersion}`);
+  console.log(`Range benchmark: ${rangeSpecifier}`);
+  console.log(`Artifact benchmark: ${options.arch}-${options.platform}`);
+  console.log("");
+
+  const scenarios = [
+    await benchmarkCase(
+      "latest version",
+      latestVersion,
+      {
+        new: {
+          run: async () => {
+            const { bytesRead, matchedVersion } = await streamUntil(
+              options.url,
+              () => true,
+            );
+            return {
+              bytesRead,
+              value: matchedVersion?.version,
+            };
+          },
+        },
+        old: {
+          run: async () => {
+            const { bytesRead, versions } = await fetchAllVersions(options.url);
+            return {
+              bytesRead,
+              value: versions[0]?.version,
+            };
+          },
+        },
+      },
+      options.iterations,
+    ),
+    await benchmarkCase(
+      "highest satisfying range",
+      latestVersion,
+      {
+        new: {
+          run: async () => {
+            const { bytesRead, matchedVersion } = await streamUntil(
+              options.url,
+              (candidate) =>
+                versionSatisfies(candidate.version, rangeSpecifier),
+            );
+            return {
+              bytesRead,
+              value: matchedVersion?.version,
+            };
+          },
+        },
+        old: {
+          run: async () => {
+            const { bytesRead, versions } = await fetchAllVersions(options.url);
+            return {
+              bytesRead,
+              value: maxSatisfying(
+                versions.map((versionData) => versionData.version),
+                rangeSpecifier,
+              ),
+            };
+          },
+        },
+      },
+      options.iterations,
+    ),
+    await benchmarkCase(
+      "exact version artifact",
+      latestArtifact.url,
+      {
+        new: {
+          run: async () => {
+            const { bytesRead, matchedVersion } = await streamUntil(
+              options.url,
+              (candidate) => candidate.version === latestVersion,
+            );
+            const artifact = matchedVersion
+              ? selectArtifact(
+                  matchedVersion.artifacts.filter(
+                    (candidate) =>
+                      candidate.platform ===
+                      `${options.arch}-${options.platform}`,
+                  ),
+                )
+              : undefined;
+            return {
+              bytesRead,
+              value: artifact?.url,
+            };
+          },
+        },
+        old: {
+          run: async () => {
+            const { bytesRead, versions } = await fetchAllVersions(options.url);
+            const versionData = versions.find(
+              (candidate) => candidate.version === latestVersion,
+            );
+            const artifact = selectArtifact(
+              versionData.artifacts.filter(
+                (candidate) =>
+                  candidate.platform === `${options.arch}-${options.platform}`,
+              ),
+            );
+            return {
+              bytesRead,
+              value: artifact?.url,
+            };
+          },
+        },
+      },
+      options.iterations,
+    ),
+  ];
+
+  for (const scenario of scenarios) {
+    const oldSummary = summarize(scenario.old);
+    const newSummary = summarize(scenario.new);
+    console.log(formatSummary(scenario.name, oldSummary, newSummary));
+    console.log("");
+  }
+}
+
+await main();

scripts/build-dist.mjs

@@ -0,0 +1,33 @@
+import { rm } from "node:fs/promises";
+import { build } from "esbuild";
+
+const builds = [
+  {
+    entryPoints: ["src/setup-uv.ts"],
+    outfile: "dist/setup/index.cjs",
+    staleOutfiles: ["dist/setup/index.mjs"],
+  },
+  {
+    entryPoints: ["src/save-cache.ts"],
+    outfile: "dist/save-cache/index.cjs",
+    staleOutfiles: ["dist/save-cache/index.mjs"],
+  },
+  {
+    entryPoints: ["src/update-known-checksums.ts"],
+    outfile: "dist/update-known-checksums/index.cjs",
+    staleOutfiles: ["dist/update-known-checksums/index.mjs"],
+  },
+];
+
+for (const { staleOutfiles, ...options } of builds) {
+  await Promise.all(
+    staleOutfiles.map((outfile) => rm(outfile, { force: true })),
+  );
+  await build({
+    bundle: true,
+    format: "cjs",
+    platform: "node",
+    target: "node24",
+    ...options,
+  });
+}

src/download/checksum/checksum.ts

@@ -6,33 +6,35 @@ import type { Architecture, Platform } from "../../utils/platforms";
 import { KNOWN_CHECKSUMS } from "./known-checksums";
 
 export async function validateChecksum(
-  checkSum: string | undefined,
+  checksum: string | undefined,
   downloadPath: string,
   arch: Architecture,
   platform: Platform,
   version: string,
 ): Promise<void> {
-  let isValid: boolean | undefined;
-  if (checkSum !== undefined && checkSum !== "") {
-    isValid = await validateFileCheckSum(downloadPath, checkSum);
-  } else {
-    core.debug("Checksum not provided. Checking known checksums.");
   const key = `${arch}-${platform}-${version}`;
-    if (key in KNOWN_CHECKSUMS) {
-      const knownChecksum = KNOWN_CHECKSUMS[`${arch}-${platform}-${version}`];
-      core.debug(`Checking checksum for ${arch}-${platform}-${version}.`);
-      isValid = await validateFileCheckSum(downloadPath, knownChecksum);
-    } else {
-      core.debug(`No known checksum found for ${key}.`);
-    }
+  const hasProvidedChecksum = checksum !== undefined && checksum !== "";
+  const checksumToUse = hasProvidedChecksum ? checksum : KNOWN_CHECKSUMS[key];
+
+  if (checksumToUse === undefined) {
+    core.debug(`No checksum found for ${key}.`);
+    return;
   }
 
-  if (isValid === false) {
-    throw new Error(`Checksum for ${downloadPath} did not match ${checkSum}.`);
+  const checksumSource = hasProvidedChecksum
+    ? "provided checksum"
+    : `KNOWN_CHECKSUMS entry for ${key}`;
+
+  core.debug(`Validating checksum using ${checksumSource}.`);
+  const isValid = await validateFileCheckSum(downloadPath, checksumToUse);
+
+  if (!isValid) {
+    throw new Error(
+      `Checksum for ${downloadPath} did not match ${checksumToUse}.`,
+    );
   }
-  if (isValid === true) {
+
   core.debug(`Checksum for ${downloadPath} is valid.`);
-  }
 }
 
 async function validateFileCheckSum(

src/download/checksum/known-checksums.ts

@@ -1,5 +1,39 @@
 // AUTOGENERATED_DO_NOT_EDIT
 export const KNOWN_CHECKSUMS: { [key: string]: string } = {
+  "aarch64-apple-darwin-0.10.10":
+    "8a09f0ef51ee7f7170731b4cb8bde5bf9ba6da5304f49a7df6cdab42a1f37b5d",
+  "aarch64-pc-windows-msvc-0.10.10":
+    "2c6fe113f14574bc27f085751c68d3485589fcc3c3c64ed85dd1eecc2f87cffc",
+  "aarch64-unknown-linux-gnu-0.10.10":
+    "2b80457b950deda12e8d5dc3b9b7494ac143eae47f1fb11b1c6e5a8495a6421e",
+  "aarch64-unknown-linux-musl-0.10.10":
+    "d08c08b82cdcaf2bd3d928ffe844d3558dda53f90066db6ef9174157cc763252",
+  "arm-unknown-linux-musleabihf-0.10.10":
+    "ccc3c4dd5eeea4b2be829ef9bc0b8d9882389c0f303f7ec5ba668065d57e2673",
+  "armv7-unknown-linux-gnueabihf-0.10.10":
+    "032786622b52f8d0232b5ad16e25342a64f9e43576652db7bf607231021902f3",
+  "armv7-unknown-linux-musleabihf-0.10.10":
+    "f6f67b190eb28b473917c97210f89fd11d9b9393d774acd093ea738fcee68864",
+  "i686-pc-windows-msvc-0.10.10":
+    "980d7ea368cc4883f572bb85c285a647eddfc23539064d2bfaf8fbfefcc2112b",
+  "i686-unknown-linux-gnu-0.10.10":
+    "5260fbef838f8cfec44697064a5cfae08a27c6ab7ed7feab7fc946827e896952",
+  "i686-unknown-linux-musl-0.10.10":
+    "a6683ade964f8d8623098ca0c96b4311d8388b44a56a386cd795974f39fb5bd2",
+  "powerpc64le-unknown-linux-gnu-0.10.10":
+    "78939dc4fc905aca8af4be19b6c6ecc306f04c6ca9f98d144372595d9397fd0d",
+  "riscv64gc-unknown-linux-gnu-0.10.10":
+    "5eff670bf80fce9d9e50df5b4d46c415a9c0324eadf7059d97c76f89ffc33c3f",
+  "s390x-unknown-linux-gnu-0.10.10":
+    "a32d2be5600f7f42f82596ffe9d3115f020974ca7fb4f15251c5625c5481ea5e",
+  "x86_64-apple-darwin-0.10.10":
+    "dd18420591d625f9b4ca2b57a7a6fe3cce43910f02e02d90e47a4101428de14a",
+  "x86_64-pc-windows-msvc-0.10.10":
+    "d31a30f1dfb96e630a08d5a9b3f3f551254b7ed6e9b7e495f46a4232661c7252",
+  "x86_64-unknown-linux-gnu-0.10.10":
+    "3e1027f26ce8c7e4c32e2277a7fed2cb410f2f1f9320d3df97653d40e21f415b",
+  "x86_64-unknown-linux-musl-0.10.10":
+    "74544e8755fbc27559e22e29fd561bdc48f91b8bd8323e760a1130f32433bea4",
   "aarch64-apple-darwin-0.10.9":
     "a92f61e9ac9b0f29668c15f56152e4a60143fca148ff5bfadb86718472c3f376",
   "aarch64-pc-windows-msvc-0.10.9":

src/download/checksum/update-known-checksums.ts

@@ -1,59 +1,34 @@
 import { promises as fs } from "node:fs";
-import * as tc from "@actions/tool-cache";
-import { KNOWN_CHECKSUMS } from "./known-checksums";
+
+export interface ChecksumEntry {
+  key: string;
+  checksum: string;
+}
+
 export async function updateChecksums(
   filePath: string,
-  downloadUrls: string[],
+  checksumEntries: ChecksumEntry[],
 ): Promise<void> {
-  await fs.rm(filePath);
-  await fs.appendFile(
-    filePath,
-    "// AUTOGENERATED_DO_NOT_EDIT\nexport const KNOWN_CHECKSUMS: { [key: string]: string } = {\n",
-  );
-  let firstLine = true;
-  for (const downloadUrl of downloadUrls) {
-    const key = getKey(downloadUrl);
-    if (key === undefined) {
+  const deduplicatedEntries = new Map<string, string>();
+
+  for (const entry of checksumEntries) {
+    if (deduplicatedEntries.has(entry.key)) {
       continue;
     }
-    const checksum = await getOrDownloadChecksum(key, downloadUrl);
-    if (!firstLine) {
-      await fs.appendFile(filePath, ",\n");
-    }
-    await fs.appendFile(filePath, `  "${key}":\n    "${checksum}"`);
-    firstLine = false;
-  }
-  await fs.appendFile(filePath, ",\n};\n");
-}
 
-function getKey(downloadUrl: string): string | undefined {
-  // https://github.com/astral-sh/uv/releases/download/0.3.2/uv-aarch64-apple-darwin.tar.gz.sha256
-  const parts = downloadUrl.split("/");
-  const fileName = parts[parts.length - 1];
-  if (fileName.startsWith("source")) {
-    return undefined;
+    deduplicatedEntries.set(entry.key, entry.checksum);
   }
-  const name = fileName.split(".")[0].split("uv-")[1];
-  const version = parts[parts.length - 2];
-  return `${name}-${version}`;
-}
 
-async function getOrDownloadChecksum(
-  key: string,
-  downloadUrl: string,
-): Promise<string> {
-  let checksum = "";
-  if (key in KNOWN_CHECKSUMS) {
-    checksum = KNOWN_CHECKSUMS[key];
-  } else {
-    const content = await downloadAssetContent(downloadUrl);
-    checksum = content.split(" ")[0].trim();
-  }
-  return checksum;
-}
+  const body = [...deduplicatedEntries.entries()]
+    .map(([key, checksum]) => `  "${key}":\n    "${checksum}"`)
+    .join(",\n");
 
-async function downloadAssetContent(downloadUrl: string): Promise<string> {
-  const downloadPath = await tc.downloadTool(downloadUrl);
-  const content = await fs.readFile(downloadPath, "utf8");
-  return content;
+  const content =
+    "// AUTOGENERATED_DO_NOT_EDIT\n" +
+    "export const KNOWN_CHECKSUMS: { [key: string]: string } = {\n" +
+    body +
+    (body === "" ? "" : ",\n") +
+    "};\n";
+
+  await fs.writeFile(filePath, content);
 }

src/download/download-version.ts

@@ -2,20 +2,22 @@ import { promises as fs } from "node:fs";
 import * as path from "node:path";
 import * as core from "@actions/core";
 import * as tc from "@actions/tool-cache";
-import type { Endpoints } from "@octokit/types";
 import * as pep440 from "@renovatebot/pep440";
 import * as semver from "semver";
-import { OWNER, REPO, TOOL_CACHE_NAME } from "../utils/constants";
-import { Octokit } from "../utils/octokit";
+import { TOOL_CACHE_NAME, VERSIONS_NDJSON_URL } from "../utils/constants";
 import type { Architecture, Platform } from "../utils/platforms";
 import { validateChecksum } from "./checksum/checksum";
 import {
-  getDownloadUrl,
+  getAllVersions as getAllManifestVersions,
   getLatestKnownVersion as getLatestVersionInManifest,
+  getManifestArtifact,
 } from "./version-manifest";
-
-type Release =
-  Endpoints["GET /repos/{owner}/{repo}/releases"]["response"]["data"][number];
+import {
+  getAllVersions as getAllVersionsFromNdjson,
+  getArtifact as getArtifactFromNdjson,
+  getHighestSatisfyingVersion as getHighestSatisfyingVersionFromNdjson,
+  getLatestVersion as getLatestVersionFromNdjson,
+} from "./versions-client";
 
 export function tryGetFromToolCache(
   arch: Architecture,
@@ -32,19 +34,26 @@ export function tryGetFromToolCache(
   return { installedPath, version: resolvedVersion };
 }
 
-export async function downloadVersionFromGithub(
+export async function downloadVersionFromNdjson(
   platform: Platform,
   arch: Architecture,
   version: string,
   checkSum: string | undefined,
   githubToken: string,
 ): Promise<{ version: string; cachedToolDir: string }> {
-  const artifact = `uv-${arch}-${platform}`;
-  const extension = getExtension(platform);
-  const downloadUrl = `https://github.com/${OWNER}/${REPO}/releases/download/${version}/${artifact}${extension}`;
+  const artifact = await getArtifactFromNdjson(version, arch, platform);
+
+  if (!artifact) {
+    throw new Error(
+      `Could not find artifact for version ${version}, arch ${arch}, platform ${platform} in ${VERSIONS_NDJSON_URL} .`,
+    );
+  }
+
+  // For the default astral-sh/versions source, checksum validation relies on
+  // user input or the built-in KNOWN_CHECKSUMS table, not NDJSON sha256 values.
   return await downloadVersion(
-    downloadUrl,
-    artifact,
+    artifact.url,
+    `uv-${arch}-${platform}`,
     platform,
     arch,
     version,
@@ -54,38 +63,32 @@ export async function downloadVersionFromGithub(
 }
 
 export async function downloadVersionFromManifest(
-  manifestUrl: string | undefined,
+  manifestUrl: string,
   platform: Platform,
   arch: Architecture,
   version: string,
   checkSum: string | undefined,
   githubToken: string,
 ): Promise<{ version: string; cachedToolDir: string }> {
-  const downloadUrl = await getDownloadUrl(
+  const artifact = await getManifestArtifact(
     manifestUrl,
     version,
     arch,
     platform,
   );
-  if (!downloadUrl) {
-    core.info(
-      `manifest-file does not contain version ${version}, arch ${arch}, platform ${platform}. Falling back to GitHub releases.`,
-    );
-    return await downloadVersionFromGithub(
-      platform,
-      arch,
-      version,
-      checkSum,
-      githubToken,
+  if (!artifact) {
+    throw new Error(
+      `manifest-file does not contain version ${version}, arch ${arch}, platform ${platform}.`,
     );
   }
+
   return await downloadVersion(
-    downloadUrl,
+    artifact.downloadUrl,
     `uv-${arch}-${platform}`,
     platform,
     arch,
     version,
-    checkSum,
+    resolveChecksum(checkSum, artifact.checksum),
     githubToken,
   );
 }
@@ -96,7 +99,7 @@ async function downloadVersion(
   platform: Platform,
   arch: Architecture,
   version: string,
-  checkSum: string | undefined,
+  checksum: string | undefined,
   githubToken: string,
 ): Promise<{ version: string; cachedToolDir: string }> {
   core.info(`Downloading uv from "${downloadUrl}" ...`);
@@ -105,14 +108,14 @@ async function downloadVersion(
     undefined,
     githubToken,
   );
-  await validateChecksum(checkSum, downloadPath, arch, platform, version);
+  await validateChecksum(checksum, downloadPath, arch, platform, version);
 
   let uvDir: string;
   if (platform === "pc-windows-msvc") {
-    // On windows extracting the zip does not create an intermediate directory
+    // On windows extracting the zip does not create an intermediate directory.
     try {
       // Try tar first as it's much faster, but only bsdtar supports zip files,
-      // so this my fail if another tar, like gnu tar, ends up being used.
+      // so this may fail if another tar, like gnu tar, ends up being used.
       uvDir = await tc.extractTar(downloadPath, undefined, "x");
     } catch (err) {
       core.info(
@@ -127,6 +130,7 @@ async function downloadVersion(
     const extractedDir = await tc.extractTar(downloadPath);
     uvDir = path.join(extractedDir, artifactName);
   }
+
   const cachedToolDir = await tc.cacheDir(
     uvDir,
     TOOL_CACHE_NAME,
@@ -136,14 +140,22 @@ async function downloadVersion(
   return { cachedToolDir, version: version };
 }
 
+function resolveChecksum(
+  checkSum: string | undefined,
+  manifestChecksum?: string,
+): string | undefined {
+  return checkSum !== undefined && checkSum !== ""
+    ? checkSum
+    : manifestChecksum;
+}
+
 function getExtension(platform: Platform): string {
   return platform === "pc-windows-msvc" ? ".zip" : ".tar.gz";
 }
 
 export async function resolveVersion(
   versionInput: string,
-  manifestFile: string | undefined,
-  githubToken: string,
+  manifestUrl: string | undefined,
   resolutionStrategy: "highest" | "lowest" = "highest",
 ): Promise<string> {
   core.debug(`Resolving version: ${versionInput}`);
@@ -155,15 +167,15 @@ export async function resolveVersion(
   if (resolveVersionSpecifierToLatest) {
     core.info("Found minimum version specifier, using latest version");
   }
-  if (manifestFile) {
+  if (manifestUrl !== undefined) {
     version =
       versionInput === "latest" || resolveVersionSpecifierToLatest
-        ? await getLatestVersionInManifest(manifestFile)
+        ? await getLatestVersionInManifest(manifestUrl)
         : versionInput;
   } else {
     version =
       versionInput === "latest" || resolveVersionSpecifierToLatest
-        ? await getLatestVersion(githubToken)
+        ? await getLatestVersionFromNdjson()
         : versionInput;
   }
   if (tc.isExplicitVersion(version)) {
@@ -175,91 +187,44 @@ export async function resolveVersion(
     }
     return version;
   }
-  const availableVersions = await getAvailableVersions(githubToken);
+
+  if (manifestUrl === undefined && resolutionStrategy === "highest") {
+    const resolvedVersion =
+      await getHighestSatisfyingVersionFromNdjson(version);
+    if (resolvedVersion !== undefined) {
+      core.debug(`Resolved version from NDJSON stream: ${resolvedVersion}`);
+      return resolvedVersion;
+    }
+
+    throw new Error(`No version found for ${version}`);
+  }
+
+  const availableVersions = await getAvailableVersions(manifestUrl);
   core.debug(`Available versions: ${availableVersions}`);
   const resolvedVersion =
     resolutionStrategy === "lowest"
       ? minSatisfying(availableVersions, version)
       : maxSatisfying(availableVersions, version);
+
   if (resolvedVersion === undefined) {
     throw new Error(`No version found for ${version}`);
   }
+
   return resolvedVersion;
 }
 
-async function getAvailableVersions(githubToken: string): Promise<string[]> {
-  core.info("Getting available versions from GitHub API...");
-  try {
-    const octokit = new Octokit({
-      auth: githubToken,
-    });
-    return await getReleaseTagNames(octokit);
-  } catch (err) {
-    if ((err as Error).message.includes("Bad credentials")) {
+async function getAvailableVersions(
+  manifestUrl: string | undefined,
+): Promise<string[]> {
+  if (manifestUrl !== undefined) {
     core.info(
-        "No (valid) GitHub token provided. Falling back to anonymous. Requests might be rate limited.",
+      `Getting available versions from manifest-file ${manifestUrl} ...`,
     );
-      const octokit = new Octokit();
-      return await getReleaseTagNames(octokit);
-    }
-    throw err;
-  }
-}
-
-async function getReleaseTagNames(octokit: Octokit): Promise<string[]> {
-  const response: Release[] = await octokit.paginate(
-    octokit.rest.repos.listReleases,
-    {
-      owner: OWNER,
-      repo: REPO,
-    },
-  );
-  const releaseTagNames = response.map((release) => release.tag_name);
-  if (releaseTagNames.length === 0) {
-    throw Error(
-      "Github API request failed while getting releases. Check the GitHub status page for outages. Try again later.",
-    );
-  }
-  return releaseTagNames;
-}
-
-async function getLatestVersion(githubToken: string) {
-  core.info("Getting latest version from GitHub API...");
-  const octokit = new Octokit({
-    auth: githubToken,
-  });
-
-  let latestRelease: { tag_name: string } | undefined;
-  try {
-    latestRelease = await getLatestRelease(octokit);
-  } catch (err) {
-    if ((err as Error).message.includes("Bad credentials")) {
-      core.info(
-        "No (valid) GitHub token provided. Falling back to anonymous. Requests might be rate limited.",
-      );
-      const octokit = new Octokit();
-      latestRelease = await getLatestRelease(octokit);
-    } else {
-      core.error(
-        "Github API request failed while getting latest release. Check the GitHub status page for outages. Try again later.",
-      );
-      throw err;
-    }
+    return await getAllManifestVersions(manifestUrl);
   }
 
-  if (!latestRelease) {
-    throw new Error("Could not determine latest release.");
-  }
-  core.debug(`Latest version: ${latestRelease.tag_name}`);
-  return latestRelease.tag_name;
-}
-
-async function getLatestRelease(octokit: Octokit) {
-  const { data: latestRelease } = await octokit.rest.repos.getLatestRelease({
-    owner: OWNER,
-    repo: REPO,
-  });
-  return latestRelease;
+  core.info(`Getting available versions from ${VERSIONS_NDJSON_URL} ...`);
+  return await getAllVersionsFromNdjson();
 }
 
 function maxSatisfying(

src/download/legacy-version-manifest.ts

@@ -0,0 +1,80 @@
+import * as core from "@actions/core";
+
+export interface ManifestEntry {
+  arch: string;
+  platform: string;
+  version: string;
+  downloadUrl: string;
+  checksum?: string;
+  variant?: string;
+  archiveFormat?: string;
+}
+
+interface LegacyManifestEntry {
+  arch: string;
+  platform: string;
+  version: string;
+  downloadUrl: string;
+  checksum?: string;
+}
+
+const warnedLegacyManifestUrls = new Set<string>();
+
+export function parseLegacyManifestEntries(
+  parsedEntries: unknown[],
+  manifestUrl: string,
+): ManifestEntry[] {
+  warnAboutLegacyManifestFormat(manifestUrl);
+
+  return parsedEntries.map((entry, index) => {
+    if (!isLegacyManifestEntry(entry)) {
+      throw new Error(
+        `Invalid legacy manifest-file entry at index ${index} in ${manifestUrl}.`,
+      );
+    }
+
+    return {
+      arch: entry.arch,
+      checksum: entry.checksum,
+      downloadUrl: entry.downloadUrl,
+      platform: entry.platform,
+      version: entry.version,
+    };
+  });
+}
+
+export function clearLegacyManifestWarnings(): void {
+  warnedLegacyManifestUrls.clear();
+}
+
+function warnAboutLegacyManifestFormat(manifestUrl: string): void {
+  if (warnedLegacyManifestUrls.has(manifestUrl)) {
+    return;
+  }
+
+  warnedLegacyManifestUrls.add(manifestUrl);
+  core.warning(
+    `manifest-file ${manifestUrl} uses the legacy JSON array format, which is deprecated. Please migrate to the astral-sh/versions NDJSON format before the next major release.`,
+  );
+}
+
+function isLegacyManifestEntry(value: unknown): value is LegacyManifestEntry {
+  if (!isRecord(value)) {
+    return false;
+  }
+
+  const checksumIsValid =
+    typeof value.checksum === "string" || value.checksum === undefined;
+
+  return (
+    typeof value.arch === "string" &&
+    checksumIsValid &&
+    typeof value.downloadUrl === "string" &&
+    typeof value.platform === "string" &&
+    typeof value.version === "string"
+  );
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null;
+}

src/download/variant-selection.ts

@@ -0,0 +1,39 @@
+interface VariantAwareEntry {
+  variant?: string;
+}
+
+export function selectDefaultVariant<T extends VariantAwareEntry>(
+  entries: T[],
+  duplicateEntryDescription: string,
+): T {
+  const firstEntry = entries[0];
+  if (firstEntry === undefined) {
+    throw new Error("selectDefaultVariant requires at least one candidate.");
+  }
+
+  if (entries.length === 1) {
+    return firstEntry;
+  }
+
+  const defaultEntries = entries.filter((entry) =>
+    isDefaultVariant(entry.variant),
+  );
+  if (defaultEntries.length === 1) {
+    return defaultEntries[0];
+  }
+
+  throw new Error(
+    `${duplicateEntryDescription} with variants ${formatVariants(entries)}. setup-uv currently requires a single default variant for duplicate platform entries.`,
+  );
+}
+
+function isDefaultVariant(variant: string | undefined): boolean {
+  return variant === undefined || variant === "default";
+}
+
+function formatVariants<T extends VariantAwareEntry>(entries: T[]): string {
+  return entries
+    .map((entry) => entry.variant ?? "default")
+    .sort((left, right) => left.localeCompare(right))
+    .join(", ");
+}

src/download/version-manifest.ts

@@ -1,49 +1,78 @@
-import { promises as fs } from "node:fs";
-import { join } from "node:path";
 import * as core from "@actions/core";
 import * as semver from "semver";
 import { fetch } from "../utils/fetch";
+import {
+  clearLegacyManifestWarnings,
+  type ManifestEntry,
+  parseLegacyManifestEntries,
+} from "./legacy-version-manifest";
+import { selectDefaultVariant } from "./variant-selection";
+import { type NdjsonVersion, parseVersionData } from "./versions-client";
 
-const localManifestFile = join(__dirname, "..", "..", "version-manifest.json");
-
-interface ManifestEntry {
-  version: string;
-  artifactName: string;
-  arch: string;
-  platform: string;
+export interface ManifestArtifact {
   downloadUrl: string;
+  checksum?: string;
+  archiveFormat?: string;
 }
 
+const cachedManifestEntries = new Map<string, ManifestEntry[]>();
+
 export async function getLatestKnownVersion(
-  manifestUrl: string | undefined,
+  manifestUrl: string,
 ): Promise<string> {
-  const manifestEntries = await getManifestEntries(manifestUrl);
-  return manifestEntries.reduce((a, b) =>
-    semver.gt(a.version, b.version) ? a : b,
-  ).version;
+  const versions = await getAllVersions(manifestUrl);
+  const latestVersion = versions.reduce((latest, current) =>
+    semver.gt(current, latest) ? current : latest,
+  );
+
+  return latestVersion;
 }
 
-export async function getDownloadUrl(
-  manifestUrl: string | undefined,
+export async function getAllVersions(manifestUrl: string): Promise<string[]> {
+  const manifestEntries = await getManifestEntries(manifestUrl);
+  return [...new Set(manifestEntries.map((entry) => entry.version))];
+}
+
+export async function getManifestArtifact(
+  manifestUrl: string,
   version: string,
   arch: string,
   platform: string,
-): Promise<string | undefined> {
+): Promise<ManifestArtifact | undefined> {
   const manifestEntries = await getManifestEntries(manifestUrl);
-  const entry = manifestEntries.find(
-    (entry) =>
-      entry.version === version &&
-      entry.arch === arch &&
-      entry.platform === platform,
+  const entry = selectManifestEntry(
+    manifestEntries,
+    manifestUrl,
+    version,
+    arch,
+    platform,
   );
-  return entry ? entry.downloadUrl : undefined;
+
+  if (!entry) {
+    return undefined;
+  }
+
+  return {
+    archiveFormat: entry.archiveFormat,
+    checksum: entry.checksum,
+    downloadUrl: entry.downloadUrl,
+  };
+}
+
+export function clearManifestCache(): void {
+  cachedManifestEntries.clear();
+  clearLegacyManifestWarnings();
 }
 
 async function getManifestEntries(
-  manifestUrl: string | undefined,
+  manifestUrl: string,
 ): Promise<ManifestEntry[]> {
-  let data: string;
-  if (manifestUrl !== undefined) {
+  const cachedEntries = cachedManifestEntries.get(manifestUrl);
+  if (cachedEntries !== undefined) {
+    core.debug(`Using cached manifest-file from: ${manifestUrl}`);
+    return cachedEntries;
+  }
+
   core.info(`Fetching manifest-file from: ${manifestUrl}`);
   const response = await fetch(manifestUrl, {});
   if (!response.ok) {
@@ -51,41 +80,90 @@ async function getManifestEntries(
       `Failed to fetch manifest-file: ${response.status} ${response.statusText}`,
     );
   }
-    data = await response.text();
-  } else {
-    core.info("manifest-file not provided, reading from local file.");
-    const fileContent = await fs.readFile(localManifestFile);
-    data = fileContent.toString();
-  }
 
-  return JSON.parse(data);
+  const data = await response.text();
+  const parsedEntries = parseManifestEntries(data, manifestUrl);
+  cachedManifestEntries.set(manifestUrl, parsedEntries);
+
+  return parsedEntries;
 }
 
-export async function updateVersionManifest(
+function parseManifestEntries(
+  data: string,
   manifestUrl: string,
-  downloadUrls: string[],
-): Promise<void> {
-  const manifest: ManifestEntry[] = [];
+): ManifestEntry[] {
+  const trimmed = data.trim();
+  if (trimmed === "") {
+    throw new Error(`manifest-file at ${manifestUrl} is empty.`);
+  }
 
-  for (const downloadUrl of downloadUrls) {
-    const urlParts = downloadUrl.split("/");
-    const version = urlParts[urlParts.length - 2];
-    const artifactName = urlParts[urlParts.length - 1];
-    if (!artifactName.startsWith("uv-")) {
-      continue;
+  const parsedAsJson = tryParseJson(trimmed);
+  if (Array.isArray(parsedAsJson)) {
+    return parseLegacyManifestEntries(parsedAsJson, manifestUrl);
   }
-    if (artifactName.startsWith("uv-installer")) {
-      continue;
+
+  const versions = parseVersionData(trimmed, manifestUrl);
+  return mapNdjsonVersionsToManifestEntries(versions, manifestUrl);
+}
+
+function mapNdjsonVersionsToManifestEntries(
+  versions: NdjsonVersion[],
+  manifestUrl: string,
+): ManifestEntry[] {
+  const manifestEntries: ManifestEntry[] = [];
+
+  for (const versionData of versions) {
+    for (const artifact of versionData.artifacts) {
+      const [arch, ...platformParts] = artifact.platform.split("-");
+      if (arch === undefined || platformParts.length === 0) {
+        throw new Error(
+          `Invalid artifact platform '${artifact.platform}' in manifest-file ${manifestUrl}.`,
+        );
       }
-    const artifactParts = artifactName.split(".")[0].split("-");
-    manifest.push({
-      arch: artifactParts[1],
-      artifactName: artifactName,
-      downloadUrl: downloadUrl,
-      platform: artifactName.split(`uv-${artifactParts[1]}-`)[1].split(".")[0],
-      version: version,
+
+      manifestEntries.push({
+        arch,
+        archiveFormat: artifact.archive_format,
+        checksum: artifact.sha256,
+        downloadUrl: artifact.url,
+        platform: platformParts.join("-"),
+        variant: artifact.variant,
+        version: versionData.version,
       });
     }
-  core.debug(`Updating manifest-file: ${JSON.stringify(manifest)}`);
-  await fs.writeFile(manifestUrl, JSON.stringify(manifest));
+  }
+
+  return manifestEntries;
+}
+
+function selectManifestEntry(
+  manifestEntries: ManifestEntry[],
+  manifestUrl: string,
+  version: string,
+  arch: string,
+  platform: string,
+): ManifestEntry | undefined {
+  const matches = manifestEntries.filter(
+    (candidate) =>
+      candidate.version === version &&
+      candidate.arch === arch &&
+      candidate.platform === platform,
+  );
+
+  if (matches.length === 0) {
+    return undefined;
+  }
+
+  return selectDefaultVariant(
+    matches,
+    `manifest-file ${manifestUrl} contains multiple artifacts for version ${version}, arch ${arch}, platform ${platform}`,
+  );
+}
+
+function tryParseJson(value: string): unknown {
+  try {
+    return JSON.parse(value);
+  } catch {
+    return undefined;
+  }
 }

src/download/versions-client.ts

@@ -0,0 +1,380 @@
+import * as core from "@actions/core";
+import * as pep440 from "@renovatebot/pep440";
+import * as semver from "semver";
+import { VERSIONS_NDJSON_URL } from "../utils/constants";
+import { fetch } from "../utils/fetch";
+import { selectDefaultVariant } from "./variant-selection";
+
+export interface NdjsonArtifact {
+  platform: string;
+  variant?: string;
+  url: string;
+  archive_format: string;
+  sha256: string;
+}
+
+export interface NdjsonVersion {
+  version: string;
+  artifacts: NdjsonArtifact[];
+}
+
+export interface ArtifactResult {
+  url: string;
+  sha256: string;
+  archiveFormat: string;
+}
+
+const cachedVersionData = new Map<string, NdjsonVersion[]>();
+const cachedLatestVersionData = new Map<string, NdjsonVersion>();
+const cachedVersionLookup = new Map<string, Map<string, NdjsonVersion>>();
+
+export async function fetchVersionData(
+  url: string = VERSIONS_NDJSON_URL,
+): Promise<NdjsonVersion[]> {
+  const cachedVersions = cachedVersionData.get(url);
+  if (cachedVersions !== undefined) {
+    core.debug(`Using cached NDJSON version data from ${url}`);
+    return cachedVersions;
+  }
+
+  core.info(`Fetching version data from ${url} ...`);
+  const { versions } = await readVersionData(url);
+  cacheCompleteVersionData(url, versions);
+  return versions;
+}
+
+export function parseVersionData(
+  data: string,
+  sourceDescription: string,
+): NdjsonVersion[] {
+  const versions: NdjsonVersion[] = [];
+
+  for (const [index, line] of data.split("\n").entries()) {
+    const trimmed = line.trim();
+    if (trimmed === "") {
+      continue;
+    }
+
+    versions.push(parseVersionLine(trimmed, sourceDescription, index + 1));
+  }
+
+  if (versions.length === 0) {
+    throw new Error(`No version data found in ${sourceDescription}.`);
+  }
+
+  return versions;
+}
+
+export async function getLatestVersion(): Promise<string> {
+  const cachedVersions = cachedVersionData.get(VERSIONS_NDJSON_URL);
+  const cachedLatestVersion =
+    cachedVersions?.[0] ?? cachedLatestVersionData.get(VERSIONS_NDJSON_URL);
+  if (cachedLatestVersion !== undefined) {
+    core.debug(
+      `Latest version from NDJSON cache: ${cachedLatestVersion.version}`,
+    );
+    return cachedLatestVersion.version;
+  }
+
+  const latestVersion = await findVersionData(() => true);
+  if (!latestVersion) {
+    throw new Error("No versions found in NDJSON data");
+  }
+
+  core.debug(`Latest version from NDJSON: ${latestVersion.version}`);
+  return latestVersion.version;
+}
+
+export async function getAllVersions(): Promise<string[]> {
+  const versions = await fetchVersionData();
+  return versions.map((versionData) => versionData.version);
+}
+
+export async function getHighestSatisfyingVersion(
+  versionSpecifier: string,
+  url: string = VERSIONS_NDJSON_URL,
+): Promise<string | undefined> {
+  const matchedVersion = await findVersionData(
+    (candidate) => versionSatisfies(candidate.version, versionSpecifier),
+    url,
+  );
+
+  return matchedVersion?.version;
+}
+
+export async function getArtifact(
+  version: string,
+  arch: string,
+  platform: string,
+): Promise<ArtifactResult | undefined> {
+  const versionData = await getVersionData(version);
+  if (!versionData) {
+    core.debug(`Version ${version} not found in NDJSON data`);
+    return undefined;
+  }
+
+  const targetPlatform = `${arch}-${platform}`;
+  const matchingArtifacts = versionData.artifacts.filter(
+    (candidate) => candidate.platform === targetPlatform,
+  );
+
+  if (matchingArtifacts.length === 0) {
+    core.debug(
+      `Artifact for ${targetPlatform} not found in version ${version}. Available platforms: ${versionData.artifacts
+        .map((candidate) => candidate.platform)
+        .join(", ")}`,
+    );
+    return undefined;
+  }
+
+  const artifact = selectArtifact(matchingArtifacts, version, targetPlatform);
+
+  return {
+    archiveFormat: artifact.archive_format,
+    sha256: artifact.sha256,
+    url: artifact.url,
+  };
+}
+
+export function clearCache(url?: string): void {
+  if (url === undefined) {
+    cachedVersionData.clear();
+    cachedLatestVersionData.clear();
+    cachedVersionLookup.clear();
+    return;
+  }
+
+  cachedVersionData.delete(url);
+  cachedLatestVersionData.delete(url);
+  cachedVersionLookup.delete(url);
+}
+
+function selectArtifact(
+  artifacts: NdjsonArtifact[],
+  version: string,
+  targetPlatform: string,
+): NdjsonArtifact {
+  return selectDefaultVariant(
+    artifacts,
+    `Multiple artifacts found for ${targetPlatform} in version ${version}`,
+  );
+}
+
+async function getVersionData(
+  version: string,
+  url: string = VERSIONS_NDJSON_URL,
+): Promise<NdjsonVersion | undefined> {
+  const cachedVersions = cachedVersionData.get(url);
+  if (cachedVersions !== undefined) {
+    return cachedVersions.find((candidate) => candidate.version === version);
+  }
+
+  const cachedVersion = cachedVersionLookup.get(url)?.get(version);
+  if (cachedVersion !== undefined) {
+    return cachedVersion;
+  }
+
+  return await findVersionData(
+    (candidate) => candidate.version === version,
+    url,
+  );
+}
+
+async function findVersionData(
+  predicate: (versionData: NdjsonVersion) => boolean,
+  url: string = VERSIONS_NDJSON_URL,
+): Promise<NdjsonVersion | undefined> {
+  const cachedVersions = cachedVersionData.get(url);
+  if (cachedVersions !== undefined) {
+    return cachedVersions.find(predicate);
+  }
+
+  const { matchedVersion, versions, complete } = await readVersionData(
+    url,
+    predicate,
+  );
+
+  if (complete) {
+    cacheCompleteVersionData(url, versions);
+  }
+
+  return matchedVersion;
+}
+
+async function readVersionData(
+  url: string,
+  stopWhen?: (versionData: NdjsonVersion) => boolean,
+): Promise<{
+  complete: boolean;
+  matchedVersion: NdjsonVersion | undefined;
+  versions: NdjsonVersion[];
+}> {
+  const response = await fetch(url, {});
+  if (!response.ok) {
+    throw new Error(
+      `Failed to fetch version data: ${response.status} ${response.statusText}`,
+    );
+  }
+
+  if (response.body === null) {
+    const body = await response.text();
+    const versions = parseVersionData(body, url);
+    const matchedVersion = stopWhen
+      ? versions.find((candidate) => stopWhen(candidate))
+      : undefined;
+    return { complete: true, matchedVersion, versions };
+  }
+
+  const versions: NdjsonVersion[] = [];
+  let lineNumber = 0;
+  let matchedVersion: NdjsonVersion | undefined;
+  let buffer = "";
+  const decoder = new TextDecoder();
+  const reader = response.body.getReader();
+
+  const processLine = (line: string): boolean => {
+    const trimmed = line.trim();
+    if (trimmed === "") {
+      return false;
+    }
+
+    lineNumber += 1;
+    const versionData = parseVersionLine(trimmed, url, lineNumber);
+    if (versions.length === 0) {
+      cachedLatestVersionData.set(url, versionData);
+    }
+
+    versions.push(versionData);
+    cacheVersion(url, versionData);
+
+    if (stopWhen?.(versionData) === true) {
+      matchedVersion = versionData;
+      return true;
+    }
+
+    return false;
+  };
+
+  while (true) {
+    const { done, value } = await reader.read();
+    if (done) {
+      buffer += decoder.decode();
+      break;
+    }
+
+    buffer += decoder.decode(value, { stream: true });
+    let newlineIndex = buffer.indexOf("\n");
+    while (newlineIndex !== -1) {
+      const line = buffer.slice(0, newlineIndex);
+      buffer = buffer.slice(newlineIndex + 1);
+
+      if (processLine(line)) {
+        await reader.cancel();
+        return { complete: false, matchedVersion, versions };
+      }
+
+      newlineIndex = buffer.indexOf("\n");
+    }
+  }
+
+  if (buffer.trim() !== "" && processLine(buffer)) {
+    return { complete: true, matchedVersion, versions };
+  }
+
+  if (versions.length === 0) {
+    throw new Error(`No version data found in ${url}.`);
+  }
+
+  return { complete: true, matchedVersion, versions };
+}
+
+function cacheCompleteVersionData(
+  url: string,
+  versions: NdjsonVersion[],
+): void {
+  cachedVersionData.set(url, versions);
+
+  if (versions[0] !== undefined) {
+    cachedLatestVersionData.set(url, versions[0]);
+  }
+
+  const versionLookup = new Map<string, NdjsonVersion>();
+  for (const versionData of versions) {
+    versionLookup.set(versionData.version, versionData);
+  }
+
+  cachedVersionLookup.set(url, versionLookup);
+}
+
+function cacheVersion(url: string, versionData: NdjsonVersion): void {
+  let versionLookup = cachedVersionLookup.get(url);
+  if (versionLookup === undefined) {
+    versionLookup = new Map<string, NdjsonVersion>();
+    cachedVersionLookup.set(url, versionLookup);
+  }
+
+  versionLookup.set(versionData.version, versionData);
+}
+
+function parseVersionLine(
+  line: string,
+  sourceDescription: string,
+  lineNumber: number,
+): NdjsonVersion {
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(line);
+  } catch (error) {
+    throw new Error(
+      `Failed to parse version data from ${sourceDescription} at line ${lineNumber}: ${(error as Error).message}`,
+    );
+  }
+
+  if (!isNdjsonVersion(parsed)) {
+    throw new Error(
+      `Invalid NDJSON record in ${sourceDescription} at line ${lineNumber}.`,
+    );
+  }
+
+  return parsed;
+}
+
+function versionSatisfies(version: string, versionSpecifier: string): boolean {
+  return (
+    semver.satisfies(version, versionSpecifier) ||
+    pep440.satisfies(version, versionSpecifier)
+  );
+}
+
+function isNdjsonVersion(value: unknown): value is NdjsonVersion {
+  if (!isRecord(value)) {
+    return false;
+  }
+
+  if (typeof value.version !== "string" || !Array.isArray(value.artifacts)) {
+    return false;
+  }
+
+  return value.artifacts.every(isNdjsonArtifact);
+}
+
+function isNdjsonArtifact(value: unknown): value is NdjsonArtifact {
+  if (!isRecord(value)) {
+    return false;
+  }
+
+  const variantIsValid =
+    typeof value.variant === "string" || value.variant === undefined;
+
+  return (
+    typeof value.archive_format === "string" &&
+    typeof value.platform === "string" &&
+    typeof value.sha256 === "string" &&
+    typeof value.url === "string" &&
+    variantIsValid
+  );
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null;
+}

src/setup-uv.ts

@@ -5,6 +5,7 @@ import * as exec from "@actions/exec";
 import { restoreCache } from "./cache/restore-cache";
 import {
   downloadVersionFromManifest,
+  downloadVersionFromNdjson,
   resolveVersion,
   tryGetFromToolCache,
 } from "./download/download-version";
@@ -37,6 +38,8 @@ import {
 } from "./utils/platforms";
 import { getUvVersionFromFile } from "./version/resolve";
 
+const sourceDir = __dirname;
+
 async function getPythonVersion(): Promise<string> {
   if (pythonVersion !== "") {
     return pythonVersion;
@@ -139,13 +142,22 @@ async function setupUv(
     };
   }
 
-  const downloadVersionResult = await downloadVersionFromManifest(
+  const downloadVersionResult =
+    manifestFile !== undefined
+      ? await downloadVersionFromManifest(
           manifestFile,
           platform,
           arch,
           resolvedVersion,
           checkSum,
           githubToken,
+        )
+      : await downloadVersionFromNdjson(
+          platform,
+          arch,
+          resolvedVersion,
+          checkSum,
+          githubToken,
         );
 
   return {
@@ -158,12 +170,7 @@ async function determineVersion(
   manifestFile: string | undefined,
 ): Promise<string> {
   if (versionInput !== "") {
-    return await resolveVersion(
-      versionInput,
-      manifestFile,
-      githubToken,
-      resolutionStrategy,
-    );
+    return await resolveVersion(versionInput, manifestFile, resolutionStrategy);
   }
   if (versionFileInput !== "") {
     const versionFromFile = getUvVersionFromFile(versionFileInput);
@@ -175,7 +182,6 @@ async function determineVersion(
     return await resolveVersion(
       versionFromFile,
       manifestFile,
-      githubToken,
       resolutionStrategy,
     );
   }
@@ -193,7 +199,6 @@ async function determineVersion(
   return await resolveVersion(
     versionFromUvToml || versionFromPyproject || "latest",
     manifestFile,
-    githubToken,
     resolutionStrategy,
   );
 }
@@ -305,7 +310,7 @@ function setCacheDir(): void {
 
 function addMatchers(): void {
   if (addProblemMatchers) {
-    const matchersPath = path.join(__dirname, `..${path.sep}..`, ".github");
+    const matchersPath = path.join(sourceDir, "..", "..", ".github");
     core.info(`##[add-matcher]${path.join(matchersPath, "python.json")}`);
   }
 }

src/update-known-checksums.ts

@@ -0,0 +1,81 @@
+import * as core from "@actions/core";
+import * as semver from "semver";
+import { KNOWN_CHECKSUMS } from "./download/checksum/known-checksums";
+import {
+  type ChecksumEntry,
+  updateChecksums,
+} from "./download/checksum/update-known-checksums";
+import {
+  fetchVersionData,
+  getLatestVersion,
+  type NdjsonVersion,
+} from "./download/versions-client";
+
+const VERSION_IN_CHECKSUM_KEY_PATTERN =
+  /-(\d+\.\d+\.\d+(?:[-+][0-9A-Za-z.-]+)?)$/;
+
+async function run(): Promise<void> {
+  const checksumFilePath = process.argv.slice(2)[0];
+  if (!checksumFilePath) {
+    throw new Error(
+      "Missing checksum file path. Usage: node dist/update-known-checksums/index.cjs <checksum-file-path>",
+    );
+  }
+
+  const latestVersion = await getLatestVersion();
+  const latestKnownVersion = getLatestKnownVersionFromChecksums();
+
+  if (semver.lte(latestVersion, latestKnownVersion)) {
+    core.info(
+      `Latest release (${latestVersion}) is not newer than the latest known version (${latestKnownVersion}). Skipping update.`,
+    );
+    return;
+  }
+
+  const versions = await fetchVersionData();
+  const checksumEntries = extractChecksumsFromNdjson(versions);
+  await updateChecksums(checksumFilePath, checksumEntries);
+
+  core.setOutput("latest-version", latestVersion);
+}
+
+function getLatestKnownVersionFromChecksums(): string {
+  const versions = new Set<string>();
+
+  for (const key of Object.keys(KNOWN_CHECKSUMS)) {
+    const version = extractVersionFromChecksumKey(key);
+    if (version !== undefined) {
+      versions.add(version);
+    }
+  }
+
+  const latestVersion = [...versions].sort(semver.rcompare)[0];
+  if (!latestVersion) {
+    throw new Error("Could not determine latest known version from checksums.");
+  }
+
+  return latestVersion;
+}
+
+function extractVersionFromChecksumKey(key: string): string | undefined {
+  return key.match(VERSION_IN_CHECKSUM_KEY_PATTERN)?.[1];
+}
+
+function extractChecksumsFromNdjson(
+  versions: NdjsonVersion[],
+): ChecksumEntry[] {
+  const checksums: ChecksumEntry[] = [];
+
+  for (const version of versions) {
+    for (const artifact of version.artifacts) {
+      checksums.push({
+        checksum: artifact.sha256,
+        key: `${artifact.platform}-${version.version}`,
+      });
+    }
+  }
+
+  return checksums;
+}
+
+run();

src/update-known-versions.ts

@@ -1,63 +0,0 @@
-import * as core from "@actions/core";
-import type { Endpoints } from "@octokit/types";
-import * as semver from "semver";
-import { updateChecksums } from "./download/checksum/update-known-checksums";
-import {
-  getLatestKnownVersion,
-  updateVersionManifest,
-} from "./download/version-manifest";
-import { OWNER, REPO } from "./utils/constants";
-import { Octokit } from "./utils/octokit";
-
-type Release =
-  Endpoints["GET /repos/{owner}/{repo}/releases"]["response"]["data"][number];
-
-async function run(): Promise<void> {
-  const checksumFilePath = process.argv.slice(2)[0];
-  const versionsManifestFile = process.argv.slice(2)[1];
-  const githubToken = process.argv.slice(2)[2];
-
-  const octokit = new Octokit({
-    auth: githubToken,
-  });
-
-  const { data: latestRelease } = await octokit.rest.repos.getLatestRelease({
-    owner: OWNER,
-    repo: REPO,
-  });
-
-  const latestKnownVersion = await getLatestKnownVersion(undefined);
-
-  if (semver.lte(latestRelease.tag_name, latestKnownVersion)) {
-    core.info(
-      `Latest release (${latestRelease.tag_name}) is not newer than the latest known version (${latestKnownVersion}). Skipping update.`,
-    );
-    return;
-  }
-
-  const releases: Release[] = await octokit.paginate(
-    octokit.rest.repos.listReleases,
-    {
-      owner: OWNER,
-      repo: REPO,
-    },
-  );
-  const checksumDownloadUrls: string[] = releases.flatMap((release) =>
-    release.assets
-      .filter((asset) => asset.name.endsWith(".sha256"))
-      .map((asset) => asset.browser_download_url),
-  );
-  await updateChecksums(checksumFilePath, checksumDownloadUrls);
-
-  const artifactDownloadUrls: string[] = releases.flatMap((release) =>
-    release.assets
-      .filter((asset) => !asset.name.endsWith(".sha256"))
-      .map((asset) => asset.browser_download_url),
-  );
-
-  await updateVersionManifest(versionsManifestFile, artifactDownloadUrls);
-
-  core.setOutput("latest-version", latestRelease.tag_name);
-}
-
-run();

src/utils/constants.ts

@@ -1,5 +1,5 @@
-export const REPO = "uv";
-export const OWNER = "astral-sh";
 export const TOOL_CACHE_NAME = "uv";
 export const STATE_UV_PATH = "uv-path";
 export const STATE_UV_VERSION = "uv-version";
+export const VERSIONS_NDJSON_URL =
+  "https://raw.githubusercontent.com/astral-sh/versions/main/v1/uv.ndjson";

src/utils/octokit.ts

@@ -1,34 +0,0 @@
-import type { OctokitOptions } from "@octokit/core";
-import { Octokit as Core } from "@octokit/core";
-import {
-  type PaginateInterface,
-  paginateRest,
-} from "@octokit/plugin-paginate-rest";
-import { legacyRestEndpointMethods } from "@octokit/plugin-rest-endpoint-methods";
-import { fetch as customFetch } from "./fetch";
-
-export type { RestEndpointMethodTypes } from "@octokit/plugin-rest-endpoint-methods";
-
-const DEFAULTS = {
-  baseUrl: "https://api.github.com",
-  userAgent: "setup-uv",
-};
-
-const OctokitWithPlugins = Core.plugin(paginateRest, legacyRestEndpointMethods);
-
-export const Octokit = OctokitWithPlugins.defaults(function buildDefaults(
-  options: OctokitOptions,
-): OctokitOptions {
-  return {
-    ...DEFAULTS,
-    ...options,
-    request: {
-      fetch: customFetch,
-      ...options.request,
-    },
-  };
-});
-
-export type Octokit = InstanceType<typeof OctokitWithPlugins> & {
-  paginate: PaginateInterface;
-};

tsconfig.json

@@ -1,12 +1,12 @@
 {
   "compilerOptions": {
-    "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */,
-    "module": "nodenext" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */,
-    "noImplicitAny": true /* Raise error on expressions and declarations with an implied 'any' type. */,
-    "outDir": "./lib" /* Redirect output structure to the directory. */,
-    "rootDir": "./src" /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */,
-    "strict": true /* Enable all strict type-checking options. */,
-    "target": "ES2022" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019' or 'ESNEXT'. */
+    "esModuleInterop": true,
+    "isolatedModules": true,
+    "module": "esnext",
+    "moduleResolution": "bundler",
+    "noImplicitAny": true,
+    "strict": true,
+    "target": "ES2022"
   },
-  "exclude": ["node_modules", "**/*.test.ts"]
+  "include": ["src/**/*.ts"]
 }