Open Challenge Protocol

Overview

The Open Challenge Protocol (OCP) is a declarative JSON format for expressing fitness challenges. It defines what constitutes success, not how a host application should implement the experience.

A challenge is a structured goal that evaluates rider performance against defined criteria, with optional lifecycle phases, runtime directives, and iteration/loop logic.

Challenges vs Workouts

OCP is specifically designed for Challenges, not Workouts. Understanding this distinction is critical.

Challenge Structure

A challenge is a JSON object with the following top-level fields:

{
  "id": "string",
  "version": "0.1.0",
  "name": "string",
  "description": "string (optional)",
  "sport": "cycling | running | rowing | any (optional)",

  "mode": "record | pass-fail",

  "config": { },
  "phases": [ ],
  "criteria": { },
  "loops": [ ],
  "directives": [ ],
  "record": { },
  "completion": { },

  "metadata": { }
}

Required Fields

Optional Fields

Challenge Modes

pass-fail (default): Traditional challenge with success/failure criteria. Binary outcome.

record: Best-effort challenge where the goal is to achieve the best possible result. No failure state: the challenge records your performance.

Metrics

Metrics are the canonical data points that challenges evaluate. Host applications map their raw data to these paths.

Metric Path Format

Metrics use dot-notation: category.metric

power.instant     → Current power in watts
power.wkg         → Current power in watts per kilogram
lap.index         → Current lap number (0-indexed or 1-indexed per host)
position.current  → Race position (1 = first place)

Core Metrics

Time

Power

Speed, Cadence, Heart Rate

Distance, Lap, Track

Race/Multiplayer Metrics

These are only available during race contexts:

Phases

Phases define the structure of a challenge as an ordered sequence of segments. Each phase has its own duration, targets, exit conditions, and directives.

Phase Structure

{
  "id": "effort",
  "name": "Max Effort",
  "duration": 30,
  "description": "Give everything for 30 seconds",
  "targets": { },
  "exitConditions": { },
  "directives": [ ]
}

Targets

Targets define the expected or required metrics during a phase:

{
  "targets": {
    "power": { "min": 80, "max": 150 },
    "cadence": { "min": 90, "max": 100 }
  }
}

Ramping Targets

{
  "power": {
    "mode": "ramp",
    "start": 100,
    "increment": 1,
    "per": "second"
  }
}

Conditions

A condition is a single testable expression that evaluates to true or false.

Condition Structure

{
  "metric": "power.wkg",
  "operator": ">=",
  "value": 5.0,
  "duration": 10,
  "window": "sustained"
}

Operators

Duration Windows

Logical Gates

Conditions can be combined using logical gates.

Gate Types

Example: Nested Gates

{
  "all": [
    { "metric": "time.elapsed", "operator": ">=", "value": 60 },
    {
      "any": [
        { "metric": "power.wkg", "operator": ">=", "value": 5.0 },
        { "metric": "position.current", "operator": "==", "value": 1 }
      ]
    }
  ]
}

"After 60 seconds, either hit 5.0 w/kg OR be in first place"

Lifecycle

The lifecycle defines when challenge evaluation begins and ends.

┌─────────────┐     ┌─────────────┐     ┌─────────────┐     ┌─────────────┐
│   PENDING   │ ──▶ │   ARMING    │ ──▶ │   ACTIVE    │ ──▶ │  COMPLETE   │
└─────────────┘     └─────────────┘     └─────────────┘     └─────────────┘
                          │                    │
                          │                    ▼
                          │              ┌─────────────┐
                          └────────────▶ │   FAILED    │
                                         └─────────────┘

Lifecycle Structure

{
  "lifecycle": {
    "arming": {
      "all": [
        { "metric": "time.elapsed", "operator": ">=", "value": 120 }
      ]
    },
    "timeout": 600,
    "maxAttempts": 3
  }
}

Success and Failure Criteria

Criteria Structure

{
  "criteria": {
    "success": {
      "all": [
        { "metric": "power.wkg", "operator": ">=", "value": 5.0, "duration": 10 }
      ]
    },
    "failure": {
      "any": [
        { "metric": "power.instant", "operator": "==", "value": 0, "duration": 5 }
      ]
    }
  }
}

Success-Only Challenges

Most challenges only define success criteria. The challenge continues until success or user abandonment.

Challenges with Failure Conditions

{
  "criteria": {
    "success": {
      "all": [
        { "metric": "lap.count", "operator": ">=", "value": 5 }
      ]
    },
    "failure": {
      "any": [
        { "metric": "position.current", "operator": ">", "value": 3 }
      ]
    }
  }
}

"Complete 5 laps while staying in top 3. Drop to 4th or worse = fail."

Loops

Loops enable repeating evaluation blocks with iteration-aware logic. This is essential for challenges that involve multiple intervals, progressive difficulty, or repeated actions.

Loop Structure

{
  "loops": [
    {
      "id": "sprint_intervals",
      "count": 5,
      "trigger": {
        "metric": "lap.index",
        "operator": "increasedBy",
        "value": 1
      },
      "onIteration": {
        "directives": [ ],
        "criteria": { }
      },
      "onComplete": {
        "directives": [ ]
      }
    }
  ]
}

Iteration Context Variables

Progressive Difficulty Example

{
  "loops": [
    {
      "id": "progressive_power",
      "count": 5,
      "trigger": {
        "metric": "time.elapsed",
        "operator": ">=",
        "value": "{{loopIndex * 60}}"
      },
      "onIteration": {
        "directives": [
          {
            "type": "notify",
            "message": "Interval {{loopIndex + 1}}/{{loopCount}}: Hold {{3.0 + loopIndex * 0.5}} w/kg"
          }
        ]
      }
    }
  ]
}

"5 intervals with increasing power: 3.0, 3.5, 4.0, 4.5, 5.0 w/kg"

Directives

Directives are optional runtime behaviors that the host application may execute. They are advisory: the host decides whether to honor them.

Directive Structure

{
  "directives": [
    {
      "id": "gap_warning",
      "type": "notify",
      "when": {
        "metric": "gap.ahead",
        "operator": ">",
        "value": 3.0
      },
      "params": {
        "message": "Gap widening! Push harder.",
        "priority": "high"
      },
      "cooldown": 10
    }
  ]
}

Directive Types

{
  "type": "notify",
  "params": {
    "message": "Push harder!",
    "priority": "normal | high | critical"
  }
}

{
  "type": "sound",
  "params": {
    "sound": "bell | chime | warning | success"
  }
}

{
  "type": "suggest",
  "params": {
    "metric": "power.instant",
    "target": 250
  }
}

{
  "type": "highlight",
  "params": {
    "metric": "power.wkg",
    "style": "pulse | glow | flash"
  }
}

Record (Best Effort Challenges)

For mode: "record" challenges, the record object defines what metrics to capture as the challenge result.

Record Structure

{
  "record": {
    "primary": {
      "metric": "power.max",
      "window": 5,
      "label": "5-Second Max Power",
      "unit": "watts",
      "phase": "effort"
    },
    "secondary": [
      { "metric": "power.peak", "label": "Peak Power", "unit": "watts" },
      { "metric": "cadence.max", "label": "Max Cadence", "unit": "rpm" }
    ]
  }
}

Common Primary Metrics

Completion

The completion object defines how a challenge ends and what to display in the summary.

Completion Structure

{
  "completion": {
    "condition": "phases-complete | exit-or-phases-complete | criteria-met",
    "summary": {
      "headline": "{{record.primary.value}}W",
      "subheadline": "5-Second Max Power"
    }
  }
}

Completion Conditions

Metadata

Metadata provides display hints and categorization for host applications.

{
  "metadata": {
    "difficulty": 4,
    "estimatedDuration": 120,
    "tags": ["sprint", "power", "short"],
    "author": "Ride Cave",
    "icon": "bolt",
    "color": "#FF6B00",
    "shortDescription": "Hold 5.0 w/kg for 10 seconds",
    "requirements": {
      "powerMeter": true,
      "heartRateMonitor": false
    }
  }
}

Complete Example

{
  "id": "power-surge",
  "version": "0.1.0",
  "name": "Power Surge",
  "description": "After a 2-minute warmup, hold 5.0 w/kg for 10 continuous seconds.",
  "sport": "cycling",

  "lifecycle": {
    "arming": {
      "all": [
        { "metric": "time.elapsed", "operator": ">=", "value": 120 }
      ]
    },
    "timeout": 300
  },

  "criteria": {
    "success": {
      "all": [
        {
          "metric": "power.wkg",
          "operator": ">=",
          "value": 5.0,
          "duration": 10,
          "window": "sustained"
        }
      ]
    }
  },

  "directives": [
    {
      "type": "notify",
      "params": {
        "message": "Warmup complete. Go for 5.0 w/kg!"
      },
      "once": true
    },
    {
      "type": "notify",
      "when": {
        "metric": "power.wkg",
        "operator": ">=",
        "value": 4.5
      },
      "params": {
        "message": "Almost there! Push to 5.0!",
        "priority": "high"
      },
      "cooldown": 5
    }
  ],

  "metadata": {
    "difficulty": 4,
    "estimatedDuration": 180,
    "tags": ["sprint", "power", "short"],
    "author": "Ride Cave",
    "shortDescription": "Hold 5.0 w/kg for 10 seconds"
  }
}

Evaluation Model

Evaluation Loop

The challenge evaluator runs at a fixed frequency (recommended: 10Hz).

┌─────────────────────────────────────────────────────────────┐
│                      EVALUATION TICK                        │
├─────────────────────────────────────────────────────────────┤
│  1. Collect current metrics from host                       │
│  2. Check lifecycle phase                                   │
│     - If PENDING: check arming conditions                   │
│     - If ARMING: check arming conditions → transition       │
│     - If ACTIVE: evaluate criteria + loops + directives     │
│  3. Update loop states                                      │
│  4. Check success criteria                                  │
│  5. Check failure criteria (if defined)                     │
│  6. Fire applicable directives                              │
│  7. Return evaluation result                                │
└─────────────────────────────────────────────────────────────┘

Evaluation Result

{
  "phase": "active",
  "success": false,
  "failed": false,
  "progress": {
    "percent": 75,
    "conditions": [
      {
        "metric": "power.wkg",
        "target": 5.0,
        "current": 5.2,
        "durationElapsed": 7.5,
        "durationRequired": 10,
        "met": false
      }
    ]
  },
  "loops": [
    {
      "id": "sprint_intervals",
      "iteration": 2,
      "count": 5,
      "status": "active"
    }
  ],
  "firedDirectives": ["gap_warning"],
  "elapsed": 145.3
}

Appendices

A. Environment & Portability

Challenges may reference environment metrics, values provided by the host application that describe the context in which the challenge runs.

Portability Spectrum

• Fully Portable: Challenges that only reference core metrics (power, cadence, heart rate, time, distance) work on any compliant host
• Environment-Dependent: Challenges that reference environment metrics require the host to provide those values
• Platform-Specific: Some challenges may reference features unique to a specific platform

Fallback Values

{
  "config": {
    "approachDistance": {
      "value": "{{track.length}}",
      "fallback": 250
    }
  }
}

B. Reserved Metric Paths

The following paths are reserved for future use:

• rowing.* - Rowing-specific metrics
• running.* - Running-specific metrics
• strength.* - Strength training metrics
• custom.* - Host-defined custom metrics

C. Host Implementation Notes

Hosts must implement a metric adapter that maps their internal data to OCP metric paths:

interface MetricAdapter {
  resolve(path: string): number | undefined;
  getProfile(): { ftp?: number; weight?: number; maxHr?: number };
}

D. Version History