> ## Documentation Index
> Fetch the complete documentation index at: https://hyprcode.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Building the Core Shell Loop

> How we engineered the foundations of Hypr CLI, introducing immutable message state loops and schema-validated tool pipelines.

To replicate the performance of advanced terminal coding agents, we began by establishing a solid execution environment. The core goal was to build a system that reads, writes, and executes shell directives autonomously.

## Immutable Message State Engine

At the center of Hypr is an append-only conversation log representing the single source of truth. To keep the context window lightweight, we designed a dynamic compaction algorithm. When token usage crosses a warning threshold, the engine prunes past tool logs while preserving system rules, context structures, and active goals.

## Schema-Validated Tools

To ensure system safety, every tool is validated using Zod definitions:

```typescript theme={null}
export interface ToolDef {
  name: string;
  description: string;
  schema: ZodObject<any>;
  isReadOnly: boolean;
  execute: (args: any) => Promise<ToolResult>;
}
```

This strict schema guarantees that the model cannot output malformed parameters. A permission gate middleware intercepts modifying actions, prompting the user for approval.