DI and Services

Service Lifetimes in Plugins

Registering Services in OnRegister

public void OnRegister(IServiceCollection services, OctopusConfig config)
{
    // Scoped services (per HTTP request)
    services.AddScoped<ILeaveService, LeaveService>();
    services.AddScoped<IEmployeeRepository, EmployeeRepository>();

    // Singleton (shared across all requests)
    services.AddSingleton<ILeaveCalculator, LeaveCalculator>();

    // HttpClient with typed client pattern
    services.AddHttpClient<IHRSystemClient, HRSystemClient>(client =>
    {
        client.BaseAddress = new Uri(config.Configuration["HRSystem:BaseUrl"]!);
    });

    // Options pattern
    services.Configure<HRPluginOptions>(
        config.Configuration.GetSection("HRPlugin"));

    // DbContext for this plugin's tables
    services.AddDbContext<HRDbContext>(opt =>
        opt.UseSqlServer(config.Configuration.GetConnectionString("Default")));
}

Resolving Services in OnStartAsync

public async Task OnStartAsync(IServiceProvider sp, CancellationToken ct)
{
    // For scoped services: create a scope
    using var scope = sp.CreateScope();
    var db = scope.ServiceProvider.GetRequiredService<HRDbContext>();
    await db.Database.MigrateAsync(ct);

    // For singleton services: resolve directly
    var registry = sp.GetRequiredService<MCPToolRegistry>();
    var leaveCalc = sp.GetRequiredService<ILeaveCalculator>();

    registry.Register(new MCPTool
    {
        Schema  = LeaveToolDefinition,
        Handler = (input, ctx, token) => HandleLeaveAsync(input, ctx, leaveCalc, token)
    });
}

Overriding Built-In Plugin Services

// To replace the built-in IEpisodicMemoryStore with a custom implementation:
// 1. Register SqlServerPlugin first (it registers the default)
config.AddPlugin<SqlServerPlugin>();

// 2. In your custom plugin's OnRegister, override:
public void OnRegister(IServiceCollection services, OctopusConfig config)
{
    // This replaces the last registered IEpisodicMemoryStore
    services.AddScoped<IEpisodicMemoryStore, MyCustomEpisodicStore>();
}

// The DI container uses the last registration for an interface
// SqlServerPlugin registers first, your plugin overrides it

Core Services Available to All Plugins