# Changelog State API – Change History for Tracked Vendor

> Changelog State API – Change History for Tracked Vendor is a paid API for AI agents from changelog-state-api.replit.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Returns the detected changelog update history (change events) for a single tracked vendor, filterable by change type, count, and time window.

## Facts

- Endpoint: GET https://changelog-state-api.replit.app/api/monitors/shadcn/changes
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/changelog-state-api-change-history-for-tracked-vendor-6a55706a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_43_Zyu5_sJ2kPuOyUfxiS

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 changelog-state-api-change-history-for-tracked-vendor-6a55706a
```

Example prompt: Pull the last 20 detected changelog changes for shadcn, and filter to only show breaking_signal events from the past 30 days.

## When to prefer this

Use this endpoint when you need the raw history of detected changelog change events for a specific vendor — especially when you want to filter by event type (e.g. breaking changes only) or restrict results to a recent time window. Prefer the 'releases' sibling endpoint if you want structured release notes rather than raw change detection events.

## Known failure modes

- 404 if the vendor slug is not tracked or the literal placeholder '{slug}' is used instead of a real slug
- 400 if an invalid change type enum value is passed
- 400 if limit is outside the 1–200 range
- Empty array if no changes match the since filter or the vendor has no detected history
- Payment failure (402) if the x402 payment is not properly included

## How this service works

Detected changelog update history for one tracked vendor.

## Output

A JSON array of change event records for the specified vendor, each containing the change type (e.g. new_release, version_changed, breaking_signal), detection timestamp, and relevant changelog metadata. Results are ordered by detection time and capped at the requested limit.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "pathParams": {
     "type": "object",
     "required": [
      "slug"
     ],
     "properties": {
      "slug": {
       "type": "string",
       "example": "openai",
       "pattern": "^[a-z0-9][a-z0-9-]*$",
       "maxLength": 64,
       "minLength": 1,
       "description": "Vendor slug, lowercase alphanumeric with dashes. Take one from GET /api/monitors and substitute it into the path: `{slug}` is a placeholder, and requesting those literal characters returns 404. Worked example: GET /api/monitors/openai."
      }
     }
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "type": {
       "enum": [
        "new_release",
        "version_changed",
        "date_changed",
        "title_changed",
        "breaking_signal"
       ],
       "type": "string",
       "description": "Restrict to a single change type."
      },
      "limit": {
       "type": "integer",
       "default": 50,
       "maximum": 200,
       "minimum": 1,
       "description": "Maximum number of change rows to return."
      },
      "since": {
       "type": "string",
       "format": "date-time",
       "description": "Only return changes detected at or after this instant."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "enum": [
      "json"
     ],
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   },
   "description": "Detected changelog update history (paid)"
  }
 },
 "description": "Call shape for GET /api/monitors/{slug}/changes."
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/changelog-state-api-change-history-for-tracked-vendor-6a55706a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from changelog-state-api.replit.app](https://www.zero.xyz/host/changelog-state-api.replit.app/llms.txt)