Support for long paths in run command

[zateutsch]

winapp run fails on paths exceeding ~260 chars due to Windows MAX_PATH limits. This adds longPathAware manifest support, a LongPathHelper utility, and targeted workarounds for the two main failure points: Win32 build tools (MakePri/MakeAppx) and the WinRT PackageManager API.

LongPathHelper

• EnsureExtendedLengthPrefix — adds \\?\ (or \\?\UNC\ for UNC paths) to bypass MAX_PATH in Win32 file I/O
• GetShortPath — converts long paths to 8.3 form via GetShortPathName; preserves trailing directory separators (critical for sparse registration URIs); consistent <= MaxPath boundaries throughout
• GetShortPathOrThrow — throws an actionable InvalidOperationException when shortening fails (8.3 disabled, path doesn't exist on disk)
• ValidatePathLength — fast-fails with a clear remediation message when long paths are unsupported at the system level
• GetShortPathRaw — correctly restores \\?\UNC\server\share\... → \\server\share\... (not the invalid UNC\server\share\...); handles DllNotFoundException gracefully on non-Windows

RunCommand

• Validates inputFolder.FullName early (before the status spinner) so long-path errors surface before any file system work
• Also validates the resolved manifest path immediately after resolution

PackageRegistrationService

• All three PackageManager call sites (RegisterLooseLayoutAsync, RegisterSparseAsync, InstallPackageAsync) use GetShortPathOrThrow instead of the silent GetShortPath fallback
• Sparse registration preserves the trailing separator on the external location URI

PriService

• Uses the extended-prefix dumpPath consistently for File.Exists, ReadAllTextAsync, and File.Delete — not the unprefixed dumpOutputFile

Tests

Added LongPathHelperTests with 16 unit tests covering boundary cases (== MaxPath, > MaxPath), UNC prefix handling, trailing separator preservation, and GetShortPathOrThrow throw behavior.

[github-actions]

Build Metrics Report

Binary Sizes

Artifact	Baseline	Current	Delta
CLI (ARM64)	29.22 MB	29.22 MB	📈 +5.0 KB (+0.02%)
CLI (x64)	29.67 MB	29.67 MB	📈 +5.0 KB (+0.02%)
MSIX (ARM64)	12.31 MB	12.32 MB	📈 +5.1 KB (+0.04%)
MSIX (x64)	13.09 MB	13.10 MB	📈 +7.8 KB (+0.06%)
NPM Package	25.63 MB	25.63 MB	📈 +4.2 KB (+0.02%)
NuGet Package	25.70 MB	25.71 MB	📈 +7.2 KB (+0.03%)

Test Results

✅ 714 passed out of 714 tests in 345.1s (+16 tests, -56.1s vs. baseline)

Test Coverage

❌ 21% line coverage, 37.1% branch coverage · ✅ +0.1% vs. baseline

CLI Startup Time

40ms median (x64, winapp --version) · ✅ no change vs. baseline

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Updated 2026-04-09 03:40:09 UTC · commit 51e6a29 · workflow run

[Copilot]

Pull request overview

This PR addresses issue #391 where winapp run fails on long (> ~260 char) paths by making the CLI long-path aware and adding path-handling utilities/workarounds for external tool and WinRT deployment operations.

Changes:

• Mark the CLI executable as longPathAware via an application manifest.
• Add LongPathHelper and use extended-length (\\?\) prefixes when invoking build tools (MakePri/MakeAppx).
• Work around WinRT PackageManager path limitations by converting relevant paths to 8.3 short paths and adding fast-fail validation.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/winapp-CLI/WinApp.Cli/WinApp.Cli.csproj	Wires in the application manifest to enable long-path awareness.
src/winapp-CLI/WinApp.Cli/app.manifest	Declares the process as longPathAware.
src/winapp-CLI/WinApp.Cli/Helpers/LongPathHelper.cs	Introduces long-path validation, extended-length prefixing, and 8.3 short-path conversion.
src/winapp-CLI/WinApp.Cli/Commands/RunCommand.cs	Adds a long-path validation check during run.
src/winapp-CLI/WinApp.Cli/Services/PackageRegistrationService.cs	Uses long-path validation + 8.3 short paths to keep WinRT PackageManager calls under MAX_PATH.
src/winapp-CLI/WinApp.Cli/Services/PriService.cs	Uses extended-length prefixes when calling makepri with long paths.
src/winapp-CLI/WinApp.Cli/Services/MsixService.cs	Uses extended-length prefixes when calling makeappx with long paths.
src/winapp-CLI/WinApp.Cli/NativeMethods.txt	Adds GetShortPathName for CsWin32 generation.

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[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

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[zateutsch]

@copilot apply changes based on the comments in this thread

Please do not change the PR title, and append the changes you made at the bottom of the existing PR body,

[Copilot]

@copilot apply changes based on the comments in this thread

Please do not change the PR title, and append the changes...

Applied all changes in commit ca0bc07:

• LongPathHelper.cs:166-170 — Fixed UNC prefix stripping: \\?\UNC\server\share\... now correctly converts back to \\server\share\...; extracted ExtendedLengthUncPrefix constant to avoid repetition
• LongPathHelper.cs:92-97 — Fixed boundary inconsistency: GetShortPath now uses <= MaxPath (early return) and <= MaxPath (success check); GetShortPathOrThrow uses > MaxPath to throw
• PriService.cs:209-213 — dumpPath (with extended-length prefix) is now used consistently for File.Exists, File.ReadAllTextAsync, and File.Delete
• Added LongPathHelperTests.cs with 16 unit tests

[nmetulev]

just a minor comment on linking to docs for enabling long path