[Design] PluginSystemOptions.RegisteredALCs is hidden mutable state — side-channel coupling between PluginLoader and PluginManager

Start with Plugins/FluentCMS.Infrastructure.Plugins/PluginSystemOptions.cs at the RegisteredALCs property, then trace PluginLoader.LoadPluginTypes and the PluginManager call sites that consume the list. Define the result shape described in the issue, pass it directly between the components, and remove the runtime registry from the options object. Done means the data flow is explicit and existing plugin behavior remains intact.

Summary

PluginSystemOptions contains an internal mutable list of AssemblyLoadContext instances (RegisteredALCs). This list is populated by PluginLoader and consumed by PluginManager. Using a public options/configuration object as a hidden communication channel between two components is an anti-pattern: the options class should carry only configuration values, not mutable runtime state.

Location

Plugins/FluentCMS.Infrastructure.Plugins/PluginSystemOptions.cs — line 51

Problematic Code

internal List<AssemblyLoadContext> RegisteredALCs { get; } = [];

Impact

• Hidden coupling: PluginLoader and PluginManager are implicitly coupled through the shared options object with no documented contract.
• Unexpected mutation: Any component that holds a reference to PluginSystemOptions can observe or modify the ALC list, which should be an implementation detail.
• Testing difficulty: Creating a PluginSystemOptions instance in tests doesn't give the expected clean state without knowing about this hidden list.
• Violation of SRP: PluginSystemOptions now serves two roles: configuration data-bag and runtime ALC registry.

Recommendation

Remove RegisteredALCs from PluginSystemOptions and change LoadPluginTypes to return a result type that packages both outputs together:

public record PluginLoadResult(
    IReadOnlyList<Type> PluginTypes,
    IReadOnlyList<AssemblyLoadContext> LoadContexts
);

// PluginLoader.LoadPluginTypes() returns PluginLoadResult
// PluginManager receives PluginLoadResult directly

This makes the data-flow explicit and removes the hidden state from the configuration object.

Severity

🔵 Design / Maintainability