{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://openwop.dev/spec/v1/run-diff-response.schema.json",
  "title": "RunDiffResponse",
  "description": "RFC 0054 — deterministic, replay-aware structured diff of two runs' event sequences and terminal states, returned by GET /v1/runs/{runId}:diff?against={otherRunId}. The diff is a pure function of the two event logs (see spec/v1/replay.md determinism contract).",
  "type": "object",
  "required": ["a", "b", "eventDiffs", "stateDiff"],
  "properties": {
    "a": {
      "type": "string",
      "description": "The {runId} run (the path resource)."
    },
    "b": {
      "type": "string",
      "description": "The {against} run (the query parameter)."
    },
    "divergedAtSeq": {
      "type": ["integer", "null"],
      "minimum": 0,
      "description": "Event sequence number at which the two logs first diverge; null if identical. Aligns with replay.diverged.divergencePoint in spec/v1/replay.md."
    },
    "eventDiffs": {
      "type": "array",
      "description": "Ordered per-sequence differences. Empty when the logs are identical.",
      "items": {
        "type": "object",
        "required": ["seq", "op"],
        "properties": {
          "seq": {
            "type": "integer",
            "minimum": 0,
            "description": "Event sequence number this diff entry applies to."
          },
          "op": {
            "type": "string",
            "enum": ["added", "removed", "changed"],
            "description": "added = present in b only; removed = present in a only; changed = present in both at this seq but differ by canonical comparison."
          },
          "aEvent": {
            "type": "object",
            "additionalProperties": true,
            "description": "The run-a event at this seq (omitted when op = added). Shape per run-event.schema.json."
          },
          "bEvent": {
            "type": "object",
            "additionalProperties": true,
            "description": "The run-b event at this seq (omitted when op = removed). Shape per run-event.schema.json."
          }
        },
        "additionalProperties": false
      }
    },
    "stateDiff": {
      "type": "object",
      "additionalProperties": true,
      "description": "Diff of terminal RunSnapshot states (status, variables, channels) — redaction-safe (never carries credential material)."
    },
    "truncated": {
      "type": "boolean",
      "description": "True if either run was in-flight and only a prefix was compared."
    }
  },
  "additionalProperties": false
}