---
title: 'inject-binding: Injection token disagrees with handler'
editUrl: https://github.com/Cratis/Arc.TypeScript/edit/main/Documentation/code-analysis/inject-binding.md
description: Match typed handle parameters to injected services.
---


## What

The count or provable constructor instance type of a class-valued `@inject` token disagrees with `handle` parameters. Rule: `arc-core/inject-binding` (type comparisons require type information; count checks do not).

## Why

Arc binds positional tokens. One extra leading handler parameter can consume an implicit value only when the command defines `provide()`; other mismatches cause a runtime dependency error. Opaque tokens are left to the runtime.

## Bad

```ts
@inject(OtherService)
handle(tasks: Tasks) {}
```

## Good

```ts
@inject(Tasks)
handle(tasks: Tasks) {}
```