# SignalHarness ABI Selector Collision Detector

> SignalHarness ABI Selector Collision Detector is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Detects and reports 4-byte function selector collisions within a supplied Ethereum ABI definition

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/abi_selector_collisions/invoke
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-abi-selector-collision-detector-a95cefc6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7njd4Ukb-dwnCo62tm5Kl

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 signalharness-abi-selector-collision-detector-a95cefc6 -d '<json body>'
```

Example prompt: Check this Ethereum ABI for any 4-byte function selector collisions and list any conflicts you find: [paste ABI JSON here].

## When to prefer this

Choose this endpoint when you need automated, programmatic detection of Ethereum ABI function selector collisions as part of a smart contract audit, deployment pipeline, or security workflow. It is ideal for agents building contract validation flows where the ABI is available as a string. Prefer this over manual selector computation when dealing with large or complex ABIs with many functions.

## Known failure modes

- Invalid or malformed ABI JSON input returns an error
- ABI string exceeds 65536 character limit causing rejection
- Empty or too-short input (under 2 characters) fails validation
- Payment failure prevents execution
- Ambiguous or non-standard ABI formats may produce incomplete collision detection

## How this service works

Explore 330 pay-per-call x402 API services and 27 agent-native digital products, with Base USDC pricing, secure Polar checkout, and free discovery.

## Output

Returns a JSON object containing a list of detected selector collisions (selector_collisions), any warnings, an evidence_scope field indicating the data was caller-supplied, and a service_id confirming the service used. Also includes a full receipt with payment details, latency metrics, and a SHA-256 hash of the result for verification.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "abi_collision_request": {
   "type": "string",
   "maxLength": 65536,
   "minLength": 2
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "warnings": [
    "Only supplied ABI entries are evaluated."
   ],
   "service_id": "abi_selector_collisions",
   "evidence_scope": "caller_supplied_data",
   "selector_collisions": "{\"collisions\":[],\"selector_count\":1}"
  },
  "status": "succeeded",
  "receipt": {
   "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
   "usage": [],
   "status": "succeeded",
   "network": "eip155:8453",
   "artifacts": [],
   "endedAtMs": 0,
   "latencyMs": 0,
   "paymentId": "example-payment",
   "receiptId": "example-receipt",
   "requestId": "example-request",
   "serviceId": "abi_selector_collisions",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "10000",
   "resultSha256": "3cb10511292ec2f84ccbf049ef7dd411c3867c66f4ce6f5838d7c7c16d3f3608",
   "serviceVersion": "1.0.0",
   "settlementReference": "0x0000000000000000000000000000000000000000000000000000000000000000"
  },
  "artifacts": [],
  "requestId": "example-request",
  "executionId": "example-execution"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/signalharness-abi-selector-collision-detector-a95cefc6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from signalharness.ai](https://www.zero.xyz/host/signalharness.ai/llms.txt)