Visual Studio Versions & Channels

msvc-kit discovers MSVC toolsets and Windows SDK packages from a Visual Studio channel manifest — a per-version JSON document served at a channel URL such as https://aka.ms/vs/17/release/channel. Each supported release's URL is listed in the table below.

Every channel msvc-kit knows about lives in one table, VS_CHANNELS, so Visual Studio support is data, not logic:

Major	Release	Channel URL
18	Visual Studio 2026	https://aka.ms/vs/18/stable/channel
17	Visual Studio 2022	https://aka.ms/vs/17/release/channel

Note: VS 2026 (v18) has no published release channel — that URL serves an HTML page instead of a JSON manifest. msvc-kit tracks v18 through the published stable channel. The release channel stays correct for VS 2022 (v17).

Selecting a channel

By default msvc-kit uses auto selection: it walks the table newest first and uses the first channel that actually serves a usable manifest. A Visual Studio release that upstream has not published yet is skipped with a warning, so a new release is picked up automatically once Microsoft publishes its channel.

# Default: newest channel that serves a manifest
msvc-kit download
msvc-kit list --available

# Pin a channel (major version or release year both work)
msvc-kit download --vs-channel 17
msvc-kit download --vs-channel 2022
msvc-kit list --available --vs-channel 2026

Accepted selector forms: 17, v17, vs17, 2022, auto, latest.

You can also pin the channel without touching the command line:

# Environment variable
export MSVC_KIT_VS_CHANNEL=17

# Persisted configuration
msvc-kit config --set-vs-channel 2022

Precedence: --vs-channel > MSVC_KIT_VS_CHANNEL > config file > auto.

When a channel is not published yet

Microsoft publishes a channel manifest only once the release is available. Until then its channel URL serves an HTML page instead of JSON — for example the release channel of a future, not-yet-published version such as https://aka.ms/vs/19/release/channel. msvc-kit detects this and degrades cleanly instead of failing with a parse error:

• Auto selection skips the channel and falls back to the next one. The skip is recorded next to the manifest cache and remembered for 10 minutes, so an unpublished release is not re-probed on every command; the reason is logged at debug level, not warn, because walking past an unpublished channel is the normal case:

  Visual Studio channel: Visual Studio 2026 (v18)

• Pinned selection reports a typed error, ChannelUnavailable, with the URL and the reason. It never silently falls back to another Visual Studio version, and it always talks to the network, so the “not published yet” answer is never hidden behind the 10 minute skip above.

• Transport failures (5xx, 429, 408, 407) are not treated as an unpublished channel: they surface as TransientHttp instead of falling back to an older Visual Studio, so a proxy or outage is not mistaken for “Microsoft has not released it yet”.

An unusable response (HTML, empty body, invalid JSON, or a manifest without packages) is never kept in the manifest cache, and the skip entry is dropped as soon as a channel serves a usable manifest, so the channel is picked up as soon as upstream publishes it.

Adding support for a new Visual Studio version

Adding a release is a one-row data change in src/vs_channel.rs:

1. Open src/vs_channel.rs and add an entry to the VS_CHANNELS table. Keep the table sorted newest first — auto selection relies on that order:

   pub const VS_CHANNELS: &[VsChannelEntry] = &[
       VsChannelEntry {
           major: 19,
           year: 2027,
           channel_url: "https://aka.ms/vs/19/release/channel",
       },
       VsChannelEntry {
           major: 18,
           year: 2026,
           channel_url: "https://aka.ms/vs/18/stable/channel",
       },
       // ...
   ];

2. Nothing else is required. Selection (--vs-channel 19, --vs-channel 2027), the library API, per-channel manifest caching (the manifest is cached as channel-v19.json) and the "newest first" auto fallback all read the table.

3. Add a test. src/vs_channel.rs has table tests; extend them with the new major/year pair, e.g. selectors_resolve_to_the_same_channel.

4. Update the table at the top of this page.

Zero-code escape hatch

A bare major version that is not in the table still works: it resolves through the VS_CHANNEL_URL_TEMPLATE (https://aka.ms/vs/{major}/release/channel). So msvc-kit download --vs-channel 19 targets a new release before any code change; adding the row only adds the friendly release name and makes it the auto selection candidate.

Library API

use msvc_kit::downloader::{list_available_versions_with_selection, VsManifest};
use msvc_kit::vs_channel::{VsChannelSelection, VsChannelSpec};

// Discover packages from a specific Visual Studio release
let selection = VsChannelSelection::Pinned(VsChannelSpec::from_major(18));
let versions = list_available_versions_with_selection(selection).await?;
println!("served by: {:?}", versions.channel);

// Or take whatever the newest published channel offers
let versions = msvc_kit::list_available_versions().await?;
# Ok::<(), msvc_kit::MsvcKitError>(())

DownloadOptions::builder().vs_channel("2026") pins the channel for download_msvc / download_sdk; VsManifest::fetch_with_selection returns the manifest together with the channel that served it.

Troubleshooting

Symptom	Cause	Fix
Unknown Visual Studio channel 'x'	The selector is not a major version, a release year, or auto/latest.	Use 17, 2022, auto, … — the error lists the known channels.
Visual Studio channel … is not available (pinned)	Upstream has not published that channel manifest yet.	Drop the flag, or pin an older release such as --vs-channel 2022.
Auto selection logs "skipped as unavailable"	A newer channel is registered but not published yet.	Informational — msvc-kit used the next channel. Pin a channel to silence it.