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

# Core Concepts

> Essential concepts for working with ASG Agent Cloud

# Core Concepts

Understanding these concepts will help you get the most out of ASG Agent Cloud.

## The Payment Flow

Every paid tool call follows this flow:

```mermaid theme={null}
sequenceDiagram
    participant Agent
    participant ASG
    participant Solana
    
    Agent->>ASG: Call tool (no payment)
    ASG-->>Agent: 402 + Quote
    Agent->>Solana: Send USDC
    Solana-->>Agent: TX Signature
    Agent->>ASG: Call tool (with signature)
    ASG->>Solana: Verify payment
    ASG-->>Agent: Result + Receipt
```

## Key Terms

### Quote

A **Quote** is a price commitment for a specific request. It includes:

* `quote_id` — Unique identifier
* `amount_usdc_microusd` — Price in micro-USD (1/1,000,000 of \$1)
* `expires_at` — When the quote expires (typically 60 seconds)

### Receipt

A **Receipt** is proof of completed work. It includes:

* `receipt_id` — Unique identifier
* `debited_usdc_microusd` — Actual cost (may differ from quote)
* `step_id` — Reference to the execution step

### Run

A **Run** is a container for related work. Runs have:

* **Budget** — Maximum spend limit
* **TTL** — Time-to-live before auto-cancel
* **Steps** — Individual tool executions

### Step

A **Step** is a single tool execution within a Run. Each Step:

* Has its own budget
* Generates one Receipt
* Can be retried (max 1 retry)

## Budgets

Budgets protect against runaway costs:

| Level           | Purpose                     |
| :-------------- | :-------------------------- |
| **Run Budget**  | Total spend limit for a Run |
| **Step Budget** | Max spend for a single Step |

If a budget is exceeded, you'll receive a `BUDGET_EXCEEDED` error.

## Idempotency

Every request can include an **idempotency key**. If you retry with the same key:

* Same result returned
* No duplicate charges
* Same receipt

## TTL (Time-to-Live)

Resources have TTLs:

* **Quotes** — 60 seconds default
* **GPU Leases** — Configurable, requires heartbeat *(Coming soon)*
* **Runs** — Configurable per-run

***

## Next Steps

<CardGroup cols={2}>
  <Card title="Architecture" icon="sitemap" href="/guide/architecture">
    System architecture overview
  </Card>

  <Card title="Pricing" icon="credit-card" href="/billing/pricing">
    Detailed pricing information
  </Card>
</CardGroup>