coordination · beta · free

Swarm Semaphore

Atomically admits up to a declared capacity of holders. Each holder permit expires independently, can be renewed idempotently, and can be released without exposing holder identities.

Use when

A bounded number of agents may work on the same resource concurrently.
Each holder needs an independently expiring permit.

Do not use when

Exactly one agent must own the resource; use PennyLock instead.
The holder identifier contains secrets or personal data.

Invocation contract

HTTP: /v1/tools/swarm-semaphore
Version: 0.1.0
Mode: atomic
Idempotency: required
Retention: Only hashes of the namespace, key, and holder remain in Valkey until their bounded TTLs expire. Raw identifiers are never returned or persisted in the execution ledger.
Tested with: HTTP/1.1, HTTP/2, MCP Streamable HTTP

Positive and negative examples

{
  "input": {
    "action": "acquire",
    "namespace": "crawl:example.invalid",
    "key": "render-workers",
    "capacity": 3,
    "holder": "agent-a",
    "ttl_seconds": 30
  },
  "output": {
    "action": "acquire",
    "semaphore_hash": "sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
    "configuration_matches": true,
    "capacity": 3,
    "active_holders": 1,
    "available_permits": 2,
    "acquired": true,
    "released": false,
    "already_held": false,
    "next_expiration_at": "2026-07-24T12:00:30.000Z",
    "holder_expiration_at": "2026-07-24T12:00:30.000Z"
  },
  "negative": [
    {
      "scenario": "Exactly one agent must own the resource; use PennyLock instead.",
      "expected_error": "INVALID_INPUT",
      "charged": false
    }
  ]
}

Deterministic errors

Code	Retry	Charged	Recovery
INVALID_INPUT	false	false	Correct the request to match input_schema.
TOOL_PAUSED	true	false	Wait for the operator to resume the tool.
RATE_LIMITED	true	false	Retry after the response Retry-After interval.
DEPENDENCY_UNAVAILABLE	true	false	Retry with the same idempotency identity.

Full machine manifest

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