Document default probing behavior in AssemblyLoadContext for LoadFromPath/LoadFromStream

[Copilot]

The managed assembly loading algorithm documentation didn't explain that LoadFromPath, LoadFromStream, and similar methods use default probing logic (including APP_PATHS) when called on the default AssemblyLoadContext, before attempting to load from the specified path or stream.

Changes

• Updated loading-managed.md algorithm step 3: Added explicit documentation that when the active AssemblyLoadContext is the default instance, the runtime first checks the default probing logic (TPA list, APP_PATHS) before loading from the specified path or raw assembly object.

• Updated default-probing.md managed assembly default probing section: Added clarification that assemblies found in TRUSTED_PLATFORM_ASSEMBLIES or APP_PATHS take precedence over specified paths or raw assembly objects when loading in the default AssemblyLoadContext, with concrete examples using LoadFromStream and LoadFromAssemblyPath.

This clarifies unexpected behavior where AssemblyLoadContext.Default.LoadFromStream(stream) may load an assembly from disk instead of the stream if a matching assembly exists in APP_PATHS:

// With APP_PATHS set, this may load from disk instead of stream
// if an assembly with matching name exists in APP_PATHS
var assembly = AssemblyLoadContext.Default.LoadFromStream(memoryStream);

Related: dotnet/runtime#122304

Original prompt

Update the docs at dotnet/core/dependency-loading/loading-managed to indicate that for other types of loads, if the default AssemblyLoadContext is the active one, the managed assembly default probing logic is used before loading from the specified path or raw assembly object.

Related: dotnet/runtime#122304

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Internal previews

📄 File	🔗 Preview link
docs/core/dependency-loading/default-probing.md	Default probing
docs/core/dependency-loading/loading-managed.md	Managed assembly loading algorithm - .NET Core

[elinor-fung]

@copilot also update dotnet/core/dependency-loading/default-probing to indicate that any assemblies in TRUSTED_PLATFORM_ASSEMBLIES or APP_PATHS take precedence when loading in the default AssemblyLoadContext (for example, over a specified path or raw assembly object).

[Copilot]

@copilot also update dotnet/core/dependency-loading/default-probing to indicate that any assemblies in TRUSTED_PLATFORM_ASSEMBLIES or APP_PATHS take precedence when loading in the default Assembly...

Updated default-probing.md to clarify that assemblies in TRUSTED_PLATFORM_ASSEMBLIES or APP_PATHS take precedence over specified paths or raw assembly objects when loading in the default AssemblyLoadContext. Added concrete examples using LoadFromStream and LoadFromAssemblyPath. (commit 019631d)

[Copilot]

Pull request overview

This pull request documents previously undocumented behavior in the .NET assembly loading algorithm where the default AssemblyLoadContext applies default probing logic (checking TPA list and APP_PATHS) before loading from explicitly specified paths or streams.

Changes:

• Added a step in the managed assembly loading algorithm to document that default probing runs before loading from specified paths when using the default AssemblyLoadContext
• Added explanatory paragraph with concrete examples showing that assemblies in TRUSTED_PLATFORM_ASSEMBLIES or APP_PATHS take precedence over explicitly specified paths or streams

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
docs/core/dependency-loading/loading-managed.md	Added algorithm step documenting default probing precedence for LoadFromPath/LoadFromStream methods on default AssemblyLoadContext
docs/core/dependency-loading/default-probing.md	Added explanatory paragraph with examples showing how default probing takes precedence over specified paths and streams

[adegeo]

This looks good. I had one minor suggestion to help the readability of how AssemblyLoadContext.Default will print.