release

name	release
description	Orchestrate an MSBuild release: create the tracking issue, branch, configure DARC channels and subscriptions, bump version in main, final-brand the release branch, insert into VS, and publish post-GA. Covers the full monthly release lifecycle aligned with VS shipping cadence.
argument-hint	Specify which phase to execute (0-5) and provide required inputs (THIS_RELEASE_VERSION, NEXT_VERSION, etc.)

MSBuild Release Orchestration

This skill guides an agent through the MSBuild release process defined in documentation/release-checklist.md. The checklist is the single source of truth — this skill provides context on how to execute it.

Overview

MSBuild is a component that gets inserted into Visual Studio. VS ships monthly; MSBuild must branch and prepare its bits before VS is ready to take them. See the release process doc for the full timeline diagram.

The insertion pipeline routes MSBuild branches to VS branches:

• main → VS main (daily canary)
• vs* release branch → VS main (replaces main → main after branch snap)

VS handles the progression from main → rel/insiders → rel/stable on its own schedule. MSBuild's responsibility is to have final-branded bits in VS main before the insiders snap date.

Each monthly VS release produces:

• A new vs* branch from main
• Final branding on that branch
• A version bump in main
• DARC channel/subscription updates
• A VS insertion
• Post-GA publishing to nuget.org and docs

The process is organized into 6 timeline-gated phases (0–5), each with an explicit trigger.

Execution model: This skill is designed for an interactive Copilot session. The agent walks through each phase step-by-step, but every command that modifies state (git push, DARC writes, pipeline changes, PR creation) requires user approval before execution. Read-only queries (DARC get-*, git log, etc.) can run without approval.

Required Inputs

Before starting any phase, ensure you have these values (the user must provide them — version increments are irregular and cannot be computed):

Input	Example	How to determine
PREVIOUS_RELEASE_VERSION	18.9	Previous entry in the merge-flow chain
PREVIOUS_RELEASE_EXACT_VERSION	18.9.6	The version the previous release actually shipped as. From the previous release's tracking issue, or git tag --list 'v18.9.*'. Used by Phase 5.3a.
THIS_RELEASE_VERSION	18.10	Current VersionPrefix in eng/Versions.props (drop .0)
NEXT_VERSION	18.11	User-provided — not computable from current version
BRANCH_SNAP_DATE	YYYY-MM-DD	From VS-Dates wiki — when MSBuild branches vs* from main, insertion targets VS main
INSIDERS_SNAP_DATE	YYYY-MM-DD	From VS-Dates wiki — when VS snaps main → rel/insiders; final-branded bits must be in VS main before this
STABLE_SNAP_DATE	YYYY-MM-DD	From VS-Dates wiki — when VS promotes rel/insiders → rel/stable
VS_SHIP_DATE	YYYY-MM-DD	When VS ships publicly (GA) — triggers post-release tasks
PACKAGE_VALIDATION_BASELINE_VERSION	18.9.0-preview-26330-01	See How to determine PACKAGE_VALIDATION_BASELINE_VERSION below — non-trivial: most "obvious" picks are wrong.

Version examples above track the current cycle (eng/Versions.props VersionPrefix is 18.10.0). Dates are intentionally shown as a format only — always read the real ones from the VS-Dates wiki.

How to determine PACKAGE_VALIDATION_BASELINE_VERSION

The value is the latest {{THIS_RELEASE_VERSION}}.0-preview-NNNNN-NN MSBuild package that is both:

1. Published on the public dotnet-tools feed — this is the feed the official build publishes to and that ApiCompat restores baselines from. If the version isn't here, ApiCompat fails with NU1102.
2. Produced from a commit reachable from vs{{THIS_RELEASE_VERSION}} — i.e. a commit on vs{{THIS_RELEASE_VERSION}}, or the main commit vs{{THIS_RELEASE_VERSION}} was branched from.

Two tempting wrong answers — and why they're wrong:

Wrong pick	Why it fails
❌ The release-versioned {{THIS_RELEASE_VERSION}}.X package that ships in VS / on nuget.org	Since #14277 release branches build and insert prerelease versions, exactly like main; the release-versioned variants are produced by NuGetRepack at manual publish time. They never exist on the public CI feed, so ApiCompat cannot restore them.
❌ Blindly the most recent {{THIS_RELEASE_VERSION}}.0-preview-* on dotnet-tools	After vs{{THIS_RELEASE_VERSION}} branches, main keeps producing {{THIS_RELEASE_VERSION}}.0-preview-* until this main-bump PR merges — so the most recent feed entries may be {{NEXT_VERSION}}-content builds wearing {{THIS_RELEASE_VERSION}} branding. Picking one drifts the API baseline forward and silently hides real compat breaks.

Procedure: run the helper — it does the whole resolution mechanically (requires az login with devdiv access):

pwsh ./scripts/Get-PackageValidationBaseline.ps1 -ThisReleaseVersion {{THIS_RELEASE_VERSION}}
# -> prints e.g. 18.9.0-preview-26330-01

It computes git merge-base origin/main origin/vs{{THIS_RELEASE_VERSION}}, finds the matching successful build in pipeline 9434, derives the package version from the OfficialBuildId, and verifies it on the dotnet-tools feed. If it fails, read the script's own .DESCRIPTION header for the manual equivalent rather than reproducing it here.

Prerequisites

• gh cli
• az cli
• darc cli — Arcade enforces a minimum version; if darc refuses with a "below the minimum required version" error, run .\eng\common\darc-init.ps1

Phase Summary

Phase	Trigger	Key Actions
0: Instantiate	User-initiated	Validate inputs, create GitHub tracking issue
1: Branch & Prepare	BRANCH_SNAP_DATE	Create vs* branch, DARC channel setup (batched PR), merge-flow config, VisualStudio.ChannelName
2: DARC Subscription Updates	Phase 1 branch exists (vs* created)	Retarget main-targeting subs + VMR backflow to next channel, retired-branch cleanup (batched PR), Arcade verify
3: Bump Main	Phase 2 merged	Branding PR in main (VersionPrefix → next, ApiCompat baseline, refresh OptProf baseline)
4: Final Branding	7 days before INSIDERS_SNAP_DATE	Public API promotion, OptProf bootstrap (usually a no-op), M2/QB approval only if behind schedule, babysit the VS insertion into VS main before insiders snap
5: Post-GA	VS shipped (VS_SHIP_DATE)	Resolve the exact shipped version (SDK-coupled? SDK wins over VS rel/stable), nuget.org publish, docs, GitHub release, Change Waves Learn sync, retro

DARC Batching

DARC write commands push to the maestro-configuration repo. Batch related changes into one PR:

1. Choose a branch name like release/msbuild-{{THIS_RELEASE_VERSION}}
2. Add --configuration-branch <name> --no-pr to every write command except the last
3. Last command: use --configuration-branch <name> without --no-pr to create the PR
4. Get the PR reviewed and merged

Read-only commands (get-default-channels, get-subscriptions, get-channel) don't need these flags.

Non-interactive (-q). darc add-default-channel / add-subscription prompt y/n when the target branch does not exist yet (e.g. pre-creating the vs{{NEXT_VERSION}} mapping in Phase 1.2c, or adding the new vs{{THIS_RELEASE_VERSION}} backflow in Phase 2). Console input is redirected in an agent session, so the prompt fails the command — always pass -q for these "branch doesn't exist yet" writes.

Phase 2 — what moves vs. what stays. When rotating main to the next channel, retarget only the subscriptions whose target branch is main (dotnet/dotnet @ main, dotnet/fsharp @ main). Never retarget a subscription that targets a VMR servicing/release branch (dotnet/dotnet @ release/*) — that includes the SDK band paired with the new vs{{THIS_RELEASE_VERSION}} branch and any .NET-next preview band (release/*-preview*). Those stay on VS {{THIS_RELEASE_VERSION}} so the new release branch owns their downstream flow; moving them steals it. (This bit the 18.9 release: the band and preview subs were moved and had to be reverted.)

Phase 2 — VMR backflow rotation (easy to miss). Backflow (dotnet/dotnet → msbuild, source-enabled) must rotate too when the new vs{{THIS_RELEASE_VERSION}} is paired with an SDK band (skip for a VS-only release): repoint the → main backflow to the next SDK band channel (.NET <NEXT_BAND> SDK, the channel dotnet/dotnet @ main publishes to), and add a backflow from the outgoing band channel into the new vs{{THIS_RELEASE_VERSION}} branch (mirror the prior release branch's backflow, e.g. vs18.0 ← .NET 10.0.1xx SDK). See checklist steps 2.2b / 2.3f / 2.3g.

Executing a Phase

When asked to execute a specific phase:

1. Read the full phase from documentation/release-checklist.md
2. Verify the trigger condition is met (previous phases completed)
3. Execute steps in order — respect sequential/parallel annotations
4. For DARC commands: batch writes into one configuration PR per phase
5. Record all output URLs in the tracking issue's artifact table
6. Mark checkboxes as completed in the tracking issue
7. In Phase 4 (step 4.7): if documentation/wiki/ChangeWaves.md is changed for this release, update the public Learn page at https://learn.microsoft.com/visualstudio/msbuild/change-waves. Sync the Change Waves Learn page from documentation/wiki/ChangeWaves.md on the vsXX.Y branch that is live in VS Insiders / the latest preview SDK. PR goes to MicrosoftDocs/visualstudio-docs-pr (docs/msbuild/change-waves.md); example: https://github.com/MicrosoftDocs/visualstudio-docs-pr/pull/15662.

Key Files

File	Purpose
documentation/release-checklist.md	Operational checklist — the source of truth
documentation/release.md	Process description: final branding, public API, major version steps
documentation/wiki/ChangeWaves.md	Source doc for the Learn page sync — always sync the vsXX.Y (Insiders/preview-SDK) copy, not main
MSBuild Change Waves Learn page	Public docs target to MicrosoftDocs/visualstudio-docs-pr (docs/msbuild/change-waves.md)
eng/Versions.props	VersionPrefix, PackageValidationBaselineVersion, BootstrapSdkVersion
.config/git-merge-flow-config.jsonc	Branch merge chain — update each release
azure-pipelines/vs-insertion.yml	VS insertion pipeline — AutoInsertTargetBranch mappings
azure-pipelines/vs-insertion-experimental.yml	Experimental insertion — TargetBranch parameter values
scripts/Get-PackageValidationBaseline.ps1	Phase 3.2 — resolves PackageValidationBaselineVersion deterministically (merge-base → pipeline 9434 → dotnet-tools feed)
scripts/Get-LatestOptProfDrop.ps1	Phase 3.3 — resolves the latest main OptProf drop (MSBuild-OptProf pipeline 17389) to refresh OptProfBaselineDrop in .vsts-dotnet.yml

Validation

After completing all phases, verify:

1. Branch vs{{THIS_RELEASE_VERSION}} exists and has final branding
2. Main has VersionPrefix = {{NEXT_VERSION}}.0
3. DARC: main → VS {{NEXT_VERSION}} channel, release branch → VS {{THIS_RELEASE_VERSION}} channel
4. VS insertion PR merged
5. Packages published to nuget.org
6. GitHub release created with tag v{{THIS_RELEASE_EXACT_VERSION}}
7. The Learn page https://learn.microsoft.com/visualstudio/msbuild/change-waves lists exactly the waves present in vsXX.Y (the version in VS Insiders / the latest released preview SDK), or the sync is explicitly tracked

Error Recovery

• Branch already exists: Release was partially started — check the tracking issue for progress
• DARC channel already exists: Safe to continue — add-channel is idempotent
• OptProf fails on first build: Expected — that's why we use main's OptProf data as fallback
• DARC configuration PR conflicts: Rebase the configuration branch on production and force-push

Major Version Releases

If NEXT_VERSION is a new major version (e.g., 18.x → 19.0), additional steps are needed after Phase 5. See release.md for:

• src/Shared/BuildEnvironmentHelper.cs — VS major version constants
• src/Shared/Constants.cs — version constants
• src/Framework/Telemetry/TelemetryConstants.cs — telemetry version