> ## Documentation Index
> Fetch the complete documentation index at: https://docs.51ultron.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Parallel Execution

> 75 concurrent tasks: how Ultron runs multiple agents across multiple workspaces simultaneously.

Ultron executes up to 75 tasks at the same time. This is not a queue where tasks wait their turn. It is genuine parallel execution across agents and workspaces.

## How the math works

```text theme={null}
Ultron — up to 75 parallel executions
├── Workspace A
│   ├── Cortex    → deep-diving Series A SaaS companies (3 searches in parallel)
│   ├── Specter   → enriching 10 leads (Apollo + ZeroBounce in parallel)
│   ├── Striker   → writing cold emails for 5 qualified leads
│   ├── Pulse     → drafting LinkedIn post (trend research + VIRALS scoring)
│   └── Sentinel  → monitoring system health
├── Workspace B
│   ├── Cortex    → competitive analysis on HubSpot
│   ├── Specter   → ICP matching for a new lead list
│   ├── Striker   → Day 3 follow-ups for last week's outreach
│   └── ...
└── ... up to 15 workspaces
```

5 agents × 15 workspaces = 75 concurrent task slots.

## Within each task

Parallelism doesn't stop at the task level. Inside each skill run, independent tool calls fire simultaneously:

```typescript theme={null}
// Specter enriching one lead — all three calls fire at once
const [company, contacts, emailCheck] = await Promise.all([
  search_companies({ name: "Acme Corp" }),
  search_people({ company: "Acme Corp", title: "CTO" }),
  verify_email({ email: "john@acmecorp.com" })
]);
```

A single lead enrichment that would take 30 seconds sequentially completes in 8–10 seconds with parallel execution.

## Concurrency controls

Parallelism is managed at two levels to protect against rate limit cascades:

| Level                     | Limit              | Reason                             |
| ------------------------- | ------------------ | ---------------------------------- |
| Skills per session        | Max 2 concurrent   | Prevents token-per-minute overflow |
| Tool calls per skill turn | Unlimited parallel | Independent ops always concurrent  |

If you invoke a third skill while two are running, it queues and starts the moment a slot opens.

**Rate limit handling:** On a 429 response, Ultron reads the `retry-after` header, falls back to exponential backoff (1s → 2s → 4s), and retries up to 3 times before surfacing an error.

## Why it matters

A complete outbound cycle — ICP research, lead discovery, enrichment, scoring, cold email draft, quality check — that takes a human 4 hours runs in under 15 minutes when Cortex and Specter work in parallel and hand off to Striker automatically.