{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://chorus.services/schemas/backbeat/beatframe/v1.0.0",
  "title": "BACKBEAT BeatFrame (INT-A)",
  "description": "Beat synchronization message broadcast from Pulse service to all BACKBEAT-enabled services",
  "version": "1.0.0",
  "type": "object",
  "required": [
    "type",
    "cluster_id", 
    "beat_index",
    "downbeat",
    "phase",
    "hlc",
    "deadline_at",
    "tempo_bpm",
    "window_id"
  ],
  "additionalProperties": false,
  "properties": {
    "type": {
      "type": "string",
      "const": "backbeat.beatframe.v1",
      "description": "Message type identifier for BeatFrame v1"
    },
    "cluster_id": {
      "type": "string",
      "pattern": "^[a-zA-Z0-9_-]+$",
      "minLength": 1,
      "maxLength": 64,
      "description": "Unique identifier for the BACKBEAT cluster"
    },
    "beat_index": {
      "type": "integer",
      "minimum": 0,
      "maximum": 9223372036854775807,
      "description": "Monotonically increasing beat counter since cluster start"
    },
    "downbeat": {
      "type": "boolean",
      "description": "True if this is the first beat of a new bar (every 120 beats by default)"
    },
    "phase": {
      "type": "string",
      "enum": ["plan", "execute", "review"],
      "description": "Current phase within the beat cycle"
    },
    "hlc": {
      "type": "string",
      "pattern": "^[0-9a-fA-F]{4}:[0-9a-fA-F]{4}:[0-9a-fA-F]{4}$",
      "description": "Hybrid Logical Clock timestamp for causal ordering (format: wall:logical:node)"
    },
    "deadline_at": {
      "type": "string",
      "format": "date-time",
      "description": "ISO 8601 timestamp when this beat phase must complete"
    },
    "tempo_bpm": {
      "type": "number",
      "minimum": 0.1,
      "maximum": 1000,
      "multipleOf": 0.1,
      "description": "Current tempo in beats per minute (default: 2.0 for 30-second beats)"
    },
    "window_id": {
      "type": "string",
      "pattern": "^[0-9a-fA-F]{32}$",
      "description": "Unique identifier for the current reporting window (changes every bar)"
    },
    "metadata": {
      "type": "object",
      "description": "Optional metadata for extensions and debugging",
      "additionalProperties": true,
      "properties": {
        "pulse_version": {
          "type": "string",
          "description": "Version of the Pulse service generating this beat"
        },
        "cluster_health": {
          "type": "string",
          "enum": ["healthy", "degraded", "critical"],
          "description": "Overall cluster health status"
        },
        "expected_agents": {
          "type": "integer",
          "minimum": 0,
          "description": "Number of agents expected to participate in this beat"
        }
      }
    }
  },
  "examples": [
    {
      "type": "backbeat.beatframe.v1",
      "cluster_id": "chorus-prod",
      "beat_index": 1337,
      "downbeat": false,
      "phase": "execute", 
      "hlc": "7ffd:0001:abcd",
      "deadline_at": "2025-09-05T12:30:00Z",
      "tempo_bpm": 2.0,
      "window_id": "7e9b0e6c4c9a4e59b7f2d9a3c1b2e4d5",
      "metadata": {
        "pulse_version": "1.2.3",
        "cluster_health": "healthy",
        "expected_agents": 150
      }
    },
    {
      "type": "backbeat.beatframe.v1",
      "cluster_id": "dev-cluster",
      "beat_index": 0,
      "downbeat": true,
      "phase": "plan",
      "hlc": "0001:0000:cafe",
      "deadline_at": "2025-09-05T12:00:30Z",
      "tempo_bpm": 4.0,
      "window_id": "a1b2c3d4e5f6789012345678901234ab"
    }
  ]
}