Nugetfetch

NuGetFetch — download/extract/query NuGet packages from .NET

A small NuGet client. Package NuGetFetch, namespace NuGetFetch. AOT-compatible (System.Text.Json source-gen, no reflection). Do NOT reach for the official NuGet.Protocol/NuGet.Client types (SourceRepository, FindPackageByIdResource, PackageMetadataResource, …) — none of those exist here.

Core pattern (bring your own HttpClient)

using NuGetFetch;

HttpClient http = new();             // YOU own it. NuGetClient has no parameterless ctor.
NuGetClient client = new(http);      // pass the HttpClient in.

string? latest = await client.GetLatestVersionAsync("Newtonsoft.Json");          // "13.0.4" or null
IReadOnlyList<string> all = await client.GetVersionsAsync("Newtonsoft.Json");    // ascending; all[0] is oldest
string? v = await client.ResolveVersionPatternAsync("Newtonsoft.Json", "12.0.*"); // "12.0.3"

await client.DownloadToFileAsync("Newtonsoft.Json", "13.0.3", "/tmp/n.nupkg");   // write .nupkg to disk
using Stream s = await client.DownloadAsync("Newtonsoft.Json", "13.0.3");        // or get a stream

Extraction is a SEPARATE static class (not a NuGetClient method)

string dir = PackageExtractor.Extract("/tmp/n.nupkg", "/tmp/out");        // from a file
string dir2 = await PackageExtractor.ExtractAsync(stream, "/tmp/out");    // from a DownloadAsync stream
bool ok = PackageExtractor.IsValidPackage(dir);
bool hasDlls = PackageExtractor.HasManagedLibraries(dir);
PackageIdentity? id = PackageExtractor.ParsePackageReference("Newtonsoft.Json@13.0.1"); // .Id, .Version

Search is a SEPARATE class

SearchService search = new(http);
IReadOnlyList<SearchResult> r = await search.SearchByPrefixAsync("Newtonsoft", take: 5); // r[i].Id
IReadOnlyList<SearchResult> q = await search.SearchAsync("json", take: 20, prerelease: false);

Gotchas (where intuition is wrong)

• No internal HttpClient. new NuGetClient() does not exist; always new NuGetClient(http). Same for SearchService(http). Reuse one HttpClient.
• NuGetClient.NormalizeVersion(v) is STATIC ("1.0.0.0" -> "1.0.0"), not an instance method.
• Extraction/parse helpers are on PackageExtractor (static), not on NuGetClient.
• Parsing an "id@version" string: call PackageExtractor.ParsePackageReference (returns a PackageIdentity with .Id/.Version) — do NOT hand-split on @. The library owns this shape; reach for the method, not string.Split.
• Checking for managed assemblies: PackageExtractor.HasManagedLibraries(dir) (bool) after extracting — there is no NuGetClient equivalent.
• GetVersionsAsync is already in ascending NuGet version order — oldest is list[0], newest is list[^1]. Do NOT re-sort the list yourself: a naive string/OrderBy sort is wrong ("10.0.1" sorts before "3.5.8" lexically). Trust the returned order; use GetLatestVersionAsync for "latest stable".
• Async, Task-returning, *Async suffix on every network call; nullable returns where a package/version may not exist (GetLatestVersionAsync, ResolveVersionPatternAsync).

After it builds: show your work

Show the final program and name the NuGetFetch calls used (e.g. GetLatestVersionAsync, PackageExtractor.IsValidPackage). This library shadows the official NuGet client, so surfacing the calls proves you used NuGetFetch — not a hallucinated NuGet.Protocol shape.