Document `#:include` support in file-based apps by Copilot · Pull Request #53350 · dotnet/docs

Copilot · 2026-04-22T21:11:14Z

The file-based apps article was missing the new #:include directive introduced with .NET 11 Preview 3 and now available in .NET SDK 10.0.300. This update adds directive coverage and clarifies how included files participate in compilation.

Supported directives
- Added #:include to the top-level list of supported file-based app directives.
New #:include directive section
- Added dedicated documentation for #:include.
- Added version availability note immediately under the #:include heading: .NET 11 Preview 3 and .NET SDK 10.0.300+.
- Added syntax examples for:
  - Including files from the app root and subfolders.
  - Glob patterns (for example, shared/**/*.cs).
  - MSBuild-property-based paths (for example, $(MSBuildProjectName).*.cs).
Included item behavior clarification
- Documented file type support and item mappings in .NET SDK 10.0.300:
  - *.cs -> Compile
  - *.resx -> EmbeddedResource
  - *.json -> None
  - *.razor -> Content
- Clarified that included .cs files are compiled as part of the same app and can add declarations, but can't add top-level statements.
- Documented that using glob patterns currently disables file-based app build caching.
- Added a reference to MSBuild reserved and well-known properties.

#:include helpers.cs
#:include models/customer.cs
#:include shared/**/*.cs
#:include $(MSBuildProjectName).*.cs

Internal previews

📄 File	🔗 Preview link
docs/core/sdk/file-based-apps.md	docs/core/sdk/file-based-apps

Internal previews

📄 File	🔗 Preview link
docs/core/sdk/file-based-apps.md	docs/core/sdk/file-based-apps

Agent-Logs-Url: https://github.com/dotnet/docs/sessions/27329bc4-87c0-469b-b146-55d906707455 Co-authored-by: gewarren <24882762+gewarren@users.noreply.github.com>

gewarren · 2026-04-22T21:57:14Z

@copilot Please respond to feedback.

Reordered the list of supported directives for clarity and moved the `#:project` section to a new position.

Removed duplicate section for the `#:include` directive in the documentation.

Copilot

Pull request overview

Updates the file-based apps documentation to cover the newly supported #:include directive so developers can split a file-based app across multiple source files.

Changes:

Adds #:include to the supported directives list.
Adds a new #:include subsection with examples and an availability note.

Agent-Logs-Url: https://github.com/dotnet/docs/sessions/a2dfc33b-80ca-4bce-a649-cb0f6ef97058 Co-authored-by: gewarren <24882762+gewarren@users.noreply.github.com>

Copilot · 2026-04-22T22:09:33Z

@copilot Please respond to feedback.

Done—feedback has been applied in 95713a7.

adegeo · 2026-04-29T17:30:49Z

+#:include models/customer.cs
+```
+
+The `#:include` directive is available in .NET 11 Preview 3 and .NET SDK 10.0.3xx and later.


We should wait for this to actually land in 3xx. It might not, you never know.

Do you think it's a good idea to put this up front? Someone may get here, try it, find it not working, never see that paragraph and complain it doesn't work.

I think we should put this up front, yeah, immediately under the heading.

Applied in 043d1cc. I moved the availability note directly under the #:include heading so readers see version support immediately.

gewarren · 2026-05-14T17:46:40Z

Feature PR is closed, so abandoning this PR.

DamianEdwards · 2026-05-17T16:49:13Z

This feature landed in 10.0.300 last week so reopening.

DamianEdwards · 2026-05-17T16:50:06Z

+
+Includes another C# source file in the file-based app.
+
+Included files compile as part of the same app. They can add types, top-level statements, and other declarations.


included files can't add top-level statements, only the entry-point file can have top-level statements

Fixed in 043d1cc. I removed the top-level statements claim and updated the text to describe supported declarations in included .cs files.

DamianEdwards · 2026-05-17T16:52:29Z

+
+### `#:include`
+
+Includes another C# source file in the file-based app.


#:include supports other file types, not just .cs. In .NET 10.0.300 it supports .cs, .resx, .json, and .razor, with each being mapped to the appropriate item type:

.cs -> Compile

.resx -> EmbeddedResource

.json -> None

.razor -> Content

Applied in 043d1cc. The section now documents *.cs, *.resx, *.json, and *.razor support, with their mapped item types.

DamianEdwards · 2026-05-17T16:54:50Z

+
+```csharp
+#:include helpers.cs
+#:include models/customer.cs


The path also supports globs, e.g. #:include shared/**/*.cs, but it's worth noting that globs will disable the build caching currently. Also you can use MSBuild properties too, e.g. #:include $(MSBuildProjectName).*.cs in an app.cs file will result in app.helpers.cs, etc. being included (maybe worth a link to https://learn.microsoft.com/visualstudio/msbuild/msbuild-reserved-and-well-known-properties).

Applied in 043d1cc. I added examples for glob and MSBuild-property paths, and noted that glob patterns currently disable file-based app build caching, with an MSBuild properties link.

gewarren · 2026-05-18T15:58:41Z

@copilot Please respond to all feedback.

Agent-Logs-Url: https://github.com/dotnet/docs/sessions/9e2da8dc-710b-4505-890e-2e264be1aa13 Co-authored-by: gewarren <24882762+gewarren@users.noreply.github.com>

Copilot · 2026-05-18T16:03:40Z

@copilot Please respond to all feedback.

Done—I've applied and responded to the actionable feedback in 043d1cc and follow-up wording refinements through 261ed22.

Agent-Logs-Url: https://github.com/dotnet/docs/sessions/9e2da8dc-710b-4505-890e-2e264be1aa13 Co-authored-by: gewarren <24882762+gewarren@users.noreply.github.com>

Initial plan

d8ea0eb

Copilot AI assigned Copilot and gewarren Apr 22, 2026

Copilot AI linked an issue Apr 22, 2026 that may be closed by this pull request

File-based apps can include other code files #53204

Open

Copilot started work on behalf of gewarren April 22, 2026 21:11 View session

Document #:include support for file-based apps

da16212

Agent-Logs-Url: https://github.com/dotnet/docs/sessions/27329bc4-87c0-469b-b146-55d906707455 Co-authored-by: gewarren <24882762+gewarren@users.noreply.github.com>

dotnet-policy-service Bot added the dotnet-fundamentals/svc label Apr 22, 2026

Copilot AI changed the title ~~[WIP] Update article on file-based apps with include syntax~~ Document #:include support in file-based apps Apr 22, 2026

Copilot finished work on behalf of gewarren April 22, 2026 21:14

Copilot AI requested a review from gewarren April 22, 2026 21:14

gewarren reviewed Apr 22, 2026

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Comment thread docs/core/sdk/file-based-apps.md Outdated

Comment thread docs/core/sdk/file-based-apps.md Outdated

Comment thread docs/core/sdk/file-based-apps.md Outdated

gewarren added 2 commits April 22, 2026 14:59

Reorganize supported directives in file-based apps docs

dce1256

Reordered the list of supported directives for clarity and moved the `#:project` section to a new position.

Remove duplicate #:include directive section

c26788a

Removed duplicate section for the `#:include` directive in the documentation.

gewarren reviewed Apr 22, 2026

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Comment thread docs/core/sdk/file-based-apps.md Outdated

Update docs/core/sdk/file-based-apps.md

45e2f60

gewarren approved these changes Apr 22, 2026

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gewarren marked this pull request as ready for review April 22, 2026 22:03

gewarren requested a review from a team as a code owner April 22, 2026 22:03

Copilot AI review requested due to automatic review settings April 22, 2026 22:03

Copilot started reviewing on behalf of gewarren April 22, 2026 22:03 View session

Copilot AI reviewed Apr 22, 2026

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Copilot started work on behalf of gewarren April 22, 2026 22:06 View session

Copilot AI and others added 4 commits April 22, 2026 22:07

Clarify #:include compilation behavior in file-based apps docs

94d3ead

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Refine #:include clarification wording for list clarity

b5f492a

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Adjust include clarification phrasing

70062cf

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Split include clarification into two sentences

95713a7

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Copilot finished work on behalf of gewarren April 22, 2026 22:10

Copilot AI requested a review from gewarren April 22, 2026 22:10

gewarren requested a review from adegeo April 28, 2026 17:57

adegeo added the DO NOT MERGE label Apr 29, 2026

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gewarren closed this May 14, 2026

DamianEdwards reopened this May 17, 2026

DamianEdwards reviewed May 17, 2026

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Copilot AI and others added 5 commits May 18, 2026 16:00

Expand #:include directive docs for file types and path patterns

043d1cc

Agent-Logs-Url: https://github.com/dotnet/docs/sessions/9e2da8dc-710b-4505-890e-2e264be1aa13 Co-authored-by: gewarren <24882762+gewarren@users.noreply.github.com>

Refine #:include wording for declarations and path options

a520d1e

Agent-Logs-Url: https://github.com/dotnet/docs/sessions/9e2da8dc-710b-4505-890e-2e264be1aa13 Co-authored-by: gewarren <24882762+gewarren@users.noreply.github.com>

Use active voice for included C# file compilation note

29e6e27

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Clarify included C# file compilation sentence

9bf0daf

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Tighten #:include path guidance wording

261ed22

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Copilot AI and others added 2 commits May 18, 2026 16:03

Clarify top-level statements are not supported in included files

0335113

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Use direct wording for top-level statement restriction

500b48d

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Copilot started work on behalf of gewarren May 18, 2026 16:07 View session

Copilot finished work on behalf of gewarren May 18, 2026 16:28


		Includes another C# source file in the file-based app.

		Included files compile as part of the same app. They can add types, top-level statements, and other declarations.


		### `#:include`

		Includes another C# source file in the file-based app.

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