Controlling visual studio

Controlling Visual Studio from PowerShell

Control a running Visual Studio instance from a PowerShell terminal by acquiring its EnvDTE.DTE COM automation object out of the Windows Running Object Table (ROT).

Scope: Windows-local only. Does not work over SSH, WSL, dev containers, or Codespaces — the ROT is per-Windows-session.

Layout

controlling-visual-studio/
├── SKILL.md                      ← this file
├── scripts/
│   ├── RotHelper.dll             ← prebuilt P/Invoke + ROT helper (~4 KB)
│   └── Connect-VsDte.ps1         ← bootstrap + high-level verbs
└── src/
    ├── RotHelper.cs              ← source for the DLL (auditable)
    └── build.ps1                 ← rebuild scripts/RotHelper.dll

Usage

Dot-source Connect-VsDte.ps1 once per pwsh session, then call the verbs. Substitute the absolute path to the skill folder; the script knows its own location ($PSScriptRoot) and finds RotHelper.dll next to it.

. '<skill-dir>/scripts/Connect-VsDte.ps1'

# Open a file at a specific line
Open-VsFile -Path C:\repo\src\Foo.cs -Line 42

# Execute any registered DTE command
Invoke-VsCommand 'File.SaveAll'
Invoke-VsCommand 'View.ErrorList'
Invoke-VsCommand 'Edit.FormatDocument'

# Build, with timeout
Invoke-VsBuild -TimeoutSeconds 600   # async + poll
Invoke-VsBuild -WaitForBuildToFinish # synchronous

# Direct DTE access for anything not wrapped
$dte = Get-VsDte
$dte.Debugger.CurrentMode      # 1=Design, 2=Break, 3=Run
$dte.ActiveDocument.FullName

How instance selection works

Get-VsDte picks the right Visual Studio instance using this priority:

1. Parent-process walk (ProcessHelper.FindAncestorByName($PID,'devenv')). Deterministic when pwsh was launched from VS's integrated terminal. Uses NtQueryInformationProcess — completes in milliseconds.
2. Solution-name match (-SolutionMatch '*MySolution*') when not running under devenv.
3. First instance found — last-resort fallback.

The selected DTE is cached in a script-scoped variable; subsequent calls in the same session reuse it (with a liveness check).

Verbs exposed by Connect-VsDte.ps1

Function	Purpose
Get-VsDte	Acquire (or reuse cached) DTE for the host VS instance.
Open-VsFile	Open a file, optionally jumping to Line/Column.
Invoke-VsCommand	Call DTE.ExecuteCommand(name, args).
Invoke-VsBuild	Build the solution; sync or async-with-timeout.
Invoke-WithComRetry	Wrap any DTE call to retry RPC_E_CALL_REJECTED / RETRYLATER.

Discover command names via (Get-VsDte).Commands | ? Name | Select Name.

Common pattern — open every git-changed file

. '<skill-dir>/scripts/Connect-VsDte.ps1'
$repoRoot = (& git rev-parse --show-toplevel).Trim()
git -C $repoRoot status --porcelain=v1 | ForEach-Object {
    $path = $_.Substring(3).Trim().Trim('"')
    if ($path -match ' -> ') { $path = $path -replace '^.* -> ','' }
    $full = Join-Path $repoRoot $path
    if (Test-Path -LiteralPath $full -PathType Leaf) { Open-VsFile -Path $full }
}

Performance

Per-invocation wall time on a modern dev box (cold pwsh, warm DLL):

Phase	Time
pwsh.exe startup	~300–400 ms
Add-Type -Path (load DLL)	~60–110 ms
Parent-process walk	~5 ms
ROT enumeration	~25 ms
First DTE call	~30 ms
Total	~450–550 ms

For lower latency (~5–10 ms per call) consider an in-VS named-pipe server shipped as a VSIX. Out of scope for this skill.

Rebuilding the DLL

If you change src/RotHelper.cs:

pwsh -NoProfile -File '<skill-dir>/src/build.ps1'

This regenerates scripts/RotHelper.dll.

Safety guidance

• DTE is powerful. It can build, debug, close unsaved documents, kill the debugger, save/overwrite files, and execute arbitrary registered commands. Treat it with the same caution as a terminal command.
• Query before you mutate. When unsure of state, read $dte.Solution, $dte.Debugger.CurrentMode, $dte.ActiveDocument first.
• Don't auto-confirm destructive prompts. Some ExecuteCommand calls raise UI prompts (e.g. closing dirty documents); never script SendKeys to dismiss them.
• Modal commands block the IDE (e.g. Tools.Options). Avoid invoking modal commands from automation unless the user explicitly asks.

Troubleshooting

Symptom	Cause	Fix
RotHelper.dll not found	Skill checked in without binary, or moved	Run src/build.ps1 to regenerate.
ROT empty but devenv.exe is running	Integrity-level mismatch	Match elevation between VS and pwsh.
RPC_E_CALL_REJECTED / RETRYLATER	VS busy	Wrap in Invoke-WithComRetry.
Wrong instance picked	Multiple devenvs, terminal not a child of VS	Pass -SolutionMatch '*Name*' to Get-VsDte.
MoveToLineAndOffset throws	Active item is not a text document (e.g. designer)	Open-VsFile already best-efforts this; check Document.Type.
Hangs in Invoke-VsBuild	Long build, or VS prompting	Increase -TimeoutSeconds; check VS UI for modal dialogs.
Works in Windows PowerShell, fails in pwsh 7	MTA apartment	Launch with pwsh -STA for sessions making many DTE calls.