Fix sparse-packaged apps unable to discover module-specific PRI files by yeelam-gordon · Pull Request #6376 · microsoft/WindowsAppSDK

yeelam-gordon · 2026-04-03T05:02:17Z

Summary

Fixes sparse-packaged apps (unpackaged + self-contained WinUI3 with identity via AddPackageByUriAsync) failing to locate module-specific PRI files (e.g., MyApp.pri set via ProjectPriFileName).

Why This Matters

Not an regression, it doesn't work from the first day.

While unpackaged apps that need package-identity-only APIs (e.g., Windows AI APIs) must use sparse app registration (AddPackageByUriAsync) to acquire identity. When multiple such apps share the same output directory, each needs its own module-specific PRI (via ProjectPriFileName) to avoid resource conflicts. This fix unblocks that scenario - without it, any sparse-packaged app with a custom PRI name fails to load resources.

Problem

GetDefaultPriFile() determines isPackaged=true for sparse apps because they have package identity. This causes GetDefaultPriFileForCurentModule to pass "resources.pri" to MrmGetFilePathFromName, which only searches for that exact filename - skipping the [modulename].pri fallback that unpackaged apps (the one leverage sparse app) receive.

When multiple apps share the same output directory, each needs its own module-specific PRI to avoid conflicts, but sparse apps could only find resources.pri.

Fix

When the packaged "resources.pri" search fails for apps with identity, fall back to the unpackaged discovery path (pass nullptr to MrmGetFilePathFromName) which triggers the broader search including "[modulename].pri" derived from the process executable name.

The fallback is gated on IsResourceNotFound(hr) to ensure only genuine not-found conditions trigger it, avoiding masking real errors (e.g., E_OUTOFMEMORY, E_ACCESSDENIED). If the fallback also fails, the original HRESULT from the "resources.pri" search is returned for backward compatibility so callers checking for specific errors (e.g., ERROR_FILE_NOT_FOUND) are not broken.

Changed file

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp

Existing test coverage

DefaultResourceManagerWithExePri — validates the nullptr fallback mechanism
DefaultResourceManager — validates error behavior when no PRI exists
DefaultResourceManagerWithResourcePri — validates the normal packaged path

A full sparse-app integration test requires actual sparse package registration (AddPackageByUriAsync) which is beyond unit test scope.

Validation

Builds clean with no warnings
/azp run pipeline validation

A microsoft employee must use /azp run to validate using the pipelines below.

WARNING:

Comments made by azure-pipelines bot maybe inaccurate.

Please see pipeline link to verify that the build is being ran.

For status checks on the main branch, please use TransportPackage-Foundation-PR

(https://microsoft.visualstudio.com/ProjectReunion/_build?definitionId=81063&_a=summary)

and run the build against your PR branch with the default parameters.

Sparse-packaged apps have package identity (via AddPackageByUriAsync) but deploy resources as loose files next to the executable. GetDefaultPriFile() determines isPackaged=true for these apps (since they have identity), causing GetDefaultPriFileForCurentModule to pass "resources.pri" to MrmGetFilePathFromName — which only searches for that exact filename, skipping the [modulename].pri fallback that unpackaged apps receive. When the "resources.pri" search fails for apps with identity, fall back to the unpackaged discovery path (pass nullptr to MrmGetFilePathFromName) which triggers the broader search including "[modulename].pri" derived via PathCchRenameExtension from the process executable name. If the fallback also fails, return the original HRESULT from the "resources.pri" search so callers that check for specific errors (e.g., ERROR_FILE_NOT_FOUND) are not broken. Existing test coverage: - DefaultResourceManagerWithExePri validates the nullptr fallback mechanism - DefaultResourceManager validates error behavior when no PRI exists - DefaultResourceManagerWithResourcePri validates the normal packaged path A full sparse-app integration test requires actual sparse package registration (AddPackageByUriAsync) which is beyond unit test scope. Fixes: microsoft/microsoft-ui-xaml#10856 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

yeelam-gordon · 2026-04-03T05:25:14Z

/azp run

azure-pipelines · 2026-04-03T05:25:34Z

Azure Pipelines successfully started running 1 pipeline(s).

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp

Copilot

Pull request overview

This PR updates MRTCore’s default PRI discovery logic to support sparse-packaged apps (apps with package identity but deploying PRI files as loose files next to the executable), ensuring module-specific PRI files (e.g., [modulename].pri) can be discovered when resources.pri is not present.

Changes:

After a failed packaged-module lookup ("resources.pri"), add a fallback to the unpackaged discovery path (MrmGetFilePathFromName(nullptr, ...)) for apps with identity.
Preserve the original HRESULT from the packaged-module lookup when the fallback also fails.

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp

…ound

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp

yeelam-gordon · 2026-04-03T05:53:54Z

@copilot review

…ecks

Agent-Logs-Url: https://github.com/microsoft/WindowsAppSDK/sessions/ed36cfc6-52ad-414b-8e1a-dc16f413a97e Co-authored-by: yeelam-gordon <73506701+yeelam-gordon@users.noreply.github.com>

Copilot · 2026-04-03T06:00:12Z

@copilot review

Reviewed the current state of Helper.cpp. No bugs or concerns in the changed code — the fallback is correctly gated on IsResourceNotFound(hr), the original HRESULT is preserved for backward compatibility when both paths fail, and comments are concise single-line statements.

yeelam-gordon · 2026-04-03T06:00:58Z

/azp run

azure-pipelines · 2026-04-03T06:01:15Z

Azure Pipelines successfully started running 1 pipeline(s).

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp

microsoft-github-policy-service bot added the needs-triage label Apr 3, 2026

yeelam-gordon requested a review from Copilot April 3, 2026 05:25

yeelam-gordon commented Apr 3, 2026

View reviewed changes

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp Outdated Show resolved Hide resolved

Copilot started reviewing on behalf of yeelam-gordon April 3, 2026 05:26 View session

yeelam-gordon commented Apr 3, 2026

View reviewed changes

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp Outdated Show resolved Hide resolved

yeelam-gordon commented Apr 3, 2026

View reviewed changes

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp Outdated Show resolved Hide resolved

Copilot AI reviewed Apr 3, 2026

View reviewed changes

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp Outdated Show resolved Hide resolved

Address PR review: simplify flow, shorten comment, gate on file-not-f…

f9d3f9f

…ound

yeelam-gordon commented Apr 3, 2026

View reviewed changes

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp Show resolved Hide resolved

yeelam-gordon requested a review from Copilot April 3, 2026 05:43

Add backward-compatibility comment on return hr

8ca5867

Copilot started reviewing on behalf of yeelam-gordon April 3, 2026 05:44 View session

Copilot AI reviewed Apr 3, 2026

View reviewed changes

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp Outdated Show resolved Hide resolved

Move backward-compat comment to fallback block for clarity

e09967f

yeelam-gordon requested a review from Copilot April 3, 2026 05:50

yeelam-gordon commented Apr 3, 2026

View reviewed changes

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp Outdated Show resolved Hide resolved

Copilot started reviewing on behalf of yeelam-gordon April 3, 2026 05:51 View session

yeelam-gordon commented Apr 3, 2026

View reviewed changes

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp Outdated Show resolved Hide resolved

Keep comment sentences on single lines

9c59166

Copilot AI reviewed Apr 3, 2026

View reviewed changes

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp Outdated Show resolved Hide resolved

Copilot started work on behalf of yeelam-gordon April 3, 2026 05:54 View session

yeelam-gordon and others added 2 commits April 3, 2026 13:55

Use existing IsResourceNotFound() helper instead of manual HRESULT ch…

2abd142

…ecks

Merge two-line comment into single line

d07e76b

Agent-Logs-Url: https://github.com/microsoft/WindowsAppSDK/sessions/ed36cfc6-52ad-414b-8e1a-dc16f413a97e Co-authored-by: yeelam-gordon <73506701+yeelam-gordon@users.noreply.github.com>

yeelam-gordon requested a review from Copilot April 3, 2026 05:59

Copilot started reviewing on behalf of yeelam-gordon April 3, 2026 06:00 View session

Copilot finished work on behalf of yeelam-gordon April 3, 2026 06:01

yeelam-gordon requested a review from Scottj1s April 3, 2026 06:01

Copilot AI reviewed Apr 3, 2026

View reviewed changes

dev/MRTCore/mrt/Microsoft.Windows.ApplicationModel.Resources/src/Helper.cpp Show resolved Hide resolved

yeelam-gordon linked an issue Apr 3, 2026 that may be closed by this pull request

MRT ResourceManager default constructor doesn't find [modulename].pri for sparse-packaged apps #6375

Closed

Scottj1s approved these changes Apr 6, 2026

View reviewed changes

yeelam-gordon merged commit d5afea6 into main Apr 9, 2026
53 checks passed

yeelam-gordon deleted the fix/sparse-app-pri-discovery branch April 9, 2026 01:44

Conversation

yeelam-gordon commented Apr 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary

Why This Matters

Problem

Fix

Changed file

Existing test coverage

Validation

Uh oh!

yeelam-gordon commented Apr 3, 2026

Uh oh!

azure-pipelines bot commented Apr 3, 2026

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

yeelam-gordon commented Apr 3, 2026

Uh oh!

Copilot AI commented Apr 3, 2026

Uh oh!

yeelam-gordon commented Apr 3, 2026

Uh oh!

azure-pipelines bot commented Apr 3, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

yeelam-gordon commented Apr 3, 2026 •

edited

Loading