# Concurrency Guard

> Concurrency Guard is a paid API for AI agents from phion.systems, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

Enforces concurrent execution slot limits to prevent agents or workflows from exceeding defined parallelism thresholds

## Facts

- Endpoint: POST https://phion.systems/v1/paid/trust/concurrency-guard
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/concurrency-guard-cdd4d8bd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_sVLthSERL6aFt3HdbdgWL

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability concurrency-guard-cdd4d8bd -d '<json body>'
```

Example prompt: Before starting this new scraping task, check if we have a free concurrency slot — we're set to a max of 5 simultaneous jobs and I need to make sure we're not over the limit.

## When to prefer this

Choose this endpoint when you need a lightweight, policy-enforcing gate to cap parallelism across agent tasks, API calls, or workflow jobs — especially in agentic systems where many tasks can fire simultaneously and downstream services have strict concurrency limits. Prefer it over client-side counters when you need a centralized, authoritative source of truth for slot availability shared across distributed agents.

## Known failure modes

- Slot count already at maximum — request denied, agent must wait or retry
- Missing or invalid resource/session identifier in request body
- Concurrent write conflict when multiple agents check simultaneously (race condition)
- Service unavailable or timeout if the guard store is unreachable
- Stale slot state if a previous execution did not properly release its slot

## How this service works

Enforce concurrent slot limits

## Output

Returns a decision indicating whether a new concurrent execution slot is available or the limit has been reached, along with the current active slot count and whether the requesting agent/task is permitted to proceed.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/concurrency-guard-cdd4d8bd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from phion.systems](https://www.zero.xyz/host/phion.systems/llms.txt)