jmahmood · jmahmood · Nov 17, 2025
diff --git a/README.md b/README.md
@@ -207,6 +207,62 @@ Default `DATA_DIR`: `~/.local/share/krep`
 - **Testability**: 42 unit tests, deterministic prescription logic
 - **No Unsafe Code**: `#![forbid(unsafe_code)]` in core library
 
+## Apple Watch Implementation
+
+A native watchOS version of Krep is available as a **pure Swift port** of the core business logic.
+
+### Status: Phase 1 Complete ✅
+
+- **Core Logic Ported** (~500 LOC)
+  - Types, Catalog, Engine, Progression
+  - 1:1 Swift equivalents of Rust types
+  - Full v1.1 prescription algorithm
+
+- **Unit Tests** (20+ tests)
+  - Catalog validation
+  - Prescription engine rules
+  - Progression algorithms
+
+### Location
+
+```
+cardio_watch/
+├── Package.swift              # Swift Package Manager config
+├── Sources/CardioCore/        # Business logic port
+│   ├── Types.swift            # Domain types
+│   ├── Catalog.swift          # Workout definitions
+│   ├── Engine.swift           # Prescription algorithm
+│   └── Progression.swift      # Intensity upgrades
+└── Tests/CoreTests/           # XCTest unit tests
+```
+
+### Next Steps (Requires macOS + Xcode)
+
+Phase 2-5 implementation requires Xcode on macOS:
+- **watchOS UI** (SwiftUI views)
+- **SwiftData storage** (replaces WAL)
+- **HealthKit integration** (live HR monitoring)
+- **iPhone companion app** (analytics, sync)
+
+### Documentation
+
+See **[docs/WATCH_IMPLEMENTATION.md](docs/WATCH_IMPLEMENTATION.md)** for:
+- Architecture decisions (Why Swift over FFI?)
+- Type mappings (Rust → Swift)
+- Implementation guide (UI, storage, HealthKit)
+- Build instructions (Xcode setup)
+- Migration guide (Rust data → watchOS)
+
+### Features (Planned)
+
+- ⌚ **Native watchOS app** with live workouts
+- ❤️ **HealthKit integration** for HR tracking
+- 📊 **SwiftData persistence** with iCloud sync
+- 🔔 **Complications** showing last workout
+- 📱 **iPhone companion** for analytics
+
+**Estimated completion**: 1-2 weeks for experienced iOS developer
+
 ## Testing
 
 ```bash

diff --git a/cardio_watch/Package.swift b/cardio_watch/Package.swift
@@ -0,0 +1,37 @@
+// swift-tools-version: 5.9
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "CardioWatch",
+    platforms: [
+        .watchOS(.v10),
+        .iOS(.v17)
+    ],
+    products: [
+        // Core library shared between watchOS and iOS
+        .library(
+            name: "CardioCore",
+            targets: ["CardioCore"]),
+    ],
+    dependencies: [
+        // No external dependencies for MVP
+        // Future: Add SwiftUI Charts for analytics
+    ],
+    targets: [
+        // Core business logic (port of cardio_core Rust crate)
+        .target(
+            name: "CardioCore",
+            dependencies: [],
+            path: "Sources/CardioCore"
+        ),
+
+        // Unit tests for core logic
+        .testTarget(
+            name: "CoreTests",
+            dependencies: ["CardioCore"],
+            path: "Tests/CoreTests"
+        ),
+    ]
+)
diff --git a/cardio_watch/Sources/CardioCore/Catalog.swift b/cardio_watch/Sources/CardioCore/Catalog.swift
@@ -0,0 +1,287 @@
+/// Default catalog of movements and microdose definitions.
+///
+/// This module provides the built-in movements and workouts for the system.
+/// Direct port from Rust `cardio_core/src/catalog.rs`
+
+import Foundation
+
+// MARK: - Catalog Builder
+
+/// Builds the default catalog with built-in movements and microdose definitions
+public func buildDefaultCatalog() -> Catalog {
+    var movements: [String: Movement] = [:]
+    var microdoses: [String: MicrodoseDefinition] = [:]
+
+    // ========================================================================
+    // Movements
+    // ========================================================================
+
+    movements["kb_swing_2h"] = Movement(
+        id: "kb_swing_2h",
+        name: "Kettlebell Swing (2-hand)",
+        kind: .kettlebellSwing,
+        defaultStyle: .none,
+        tags: ["vo2", "hinge", "posterior_chain"],
+        referenceUrl: "https://www.youtube.com/watch?v=YSxHifyI6s8"
+    )
+
+    movements["burpee"] = Movement(
+        id: "burpee",
+        name: "Burpee",
+        kind: .burpee,
+        defaultStyle: .burpee(.fourCount),
+        tags: ["vo2", "full_body", "bodyweight"],
+        referenceUrl: "https://www.youtube.com/watch?v=TU8QYVW0gDU"
+    )
+
+    movements["pullup"] = Movement(
+        id: "pullup",
+        name: "Pull-up",
+        kind: .pullup,
+        defaultStyle: .band(.none),
+        tags: ["gtg", "gtg_ok", "upper_body", "pull"],
+        referenceUrl: "https://www.youtube.com/watch?v=eGo4IYlbE5g"
+    )
+
+    movements["hip_cars"] = Movement(
+        id: "hip_cars",
+        name: "Hip Controlled Articular Rotations (CARs)",
+        kind: .mobilityDrill,
+        defaultStyle: .none,
+        tags: ["mobility", "hip", "gtg_ok"],
+        referenceUrl: "https://www.youtube.com/watch?v=mJRXBZGRzKg"
+    )
+
+    movements["shoulder_cars"] = Movement(
+        id: "shoulder_cars",
+        name: "Shoulder Controlled Articular Rotations (CARs)",
+        kind: .mobilityDrill,
+        defaultStyle: .none,
+        tags: ["mobility", "shoulder", "gtg_ok"],
+        referenceUrl: "https://www.youtube.com/watch?v=f9y1lOJ0v4A"
+    )
+
+    // ========================================================================
+    // Microdose Definitions
+    // ========================================================================
+
+    // VO2 EMOM: Kettlebell Swings (5 minutes)
+    microdoses["emom_kb_swing_5m"] = MicrodoseDefinition(
+        id: "emom_kb_swing_5m",
+        name: "5-Min EMOM: KB Swings (2-hand)",
+        category: .vo2,
+        suggestedDurationSeconds: 300,
+        gtgFriendly: false,
+        blocks: [
+            MicrodoseBlock(
+                movementId: "kb_swing_2h",
+                movementStyle: .none,
+                durationHintSeconds: 60,
+                metrics: [
+                    .reps(
+                        key: "reps",
+                        defaultValue: 5,
+                        min: 3,
+                        max: 15,
+                        step: 1,
+                        progressable: true
+                    )
+                ]
+            )
+        ]
+    )
+
+    // VO2 EMOM: Burpees (5 minutes)
+    microdoses["emom_burpee_5m"] = MicrodoseDefinition(
+        id: "emom_burpee_5m",
+        name: "5-Min EMOM: Burpees",
+        category: .vo2,
+        suggestedDurationSeconds: 300,
+        gtgFriendly: false,
+        blocks: [
+            MicrodoseBlock(
+                movementId: "burpee",
+                movementStyle: .burpee(.fourCount),
+                durationHintSeconds: 60,
+                metrics: [
+                    .reps(
+                        key: "reps",
+                        defaultValue: 3,
+                        min: 2,
+                        max: 10,
+                        step: 1,
+                        progressable: true
+                    )
+                ]
+            )
+        ]
+    )
+
+    // GTG: Pull-ups (banded)
+    microdoses["gtg_pullup_band"] = MicrodoseDefinition(
+        id: "gtg_pullup_band",
+        name: "GTG: Banded Pull-ups",
+        category: .gtg,
+        suggestedDurationSeconds: 30,
+        gtgFriendly: true,
+        blocks: [
+            MicrodoseBlock(
+                movementId: "pullup",
+                movementStyle: .band(.namedColour("red")),
+                durationHintSeconds: 30,
+                metrics: [
+                    .reps(
+                        key: "reps",
+                        defaultValue: 3,
+                        min: 1,
+                        max: 8,
+                        step: 1,
+                        progressable: true
+                    ),
+                    .band(
+                        key: "band",
+                        defaultValue: "red",
+                        progressable: false
+                    )
+                ]
+            )
+        ]
+    )
+
+    // Mobility: Hip CARs
+    microdoses["mobility_hip_cars"] = MicrodoseDefinition(
+        id: "mobility_hip_cars",
+        name: "Hip CARs (3 reps each side)",
+        category: .mobility,
+        suggestedDurationSeconds: 120,
+        gtgFriendly: true,
+        blocks: [
+            MicrodoseBlock(
+                movementId: "hip_cars",
+                movementStyle: .none,
+                durationHintSeconds: 120,
+                metrics: [
+                    .reps(
+                        key: "reps_per_side",
+                        defaultValue: 3,
+                        min: 2,
+                        max: 5,
+                        step: 1,
+                        progressable: false
+                    )
+                ]
+            )
+        ]
+    )
+
+    // Mobility: Shoulder CARs
+    microdoses["mobility_shoulder_cars"] = MicrodoseDefinition(
+        id: "mobility_shoulder_cars",
+        name: "Shoulder CARs (3 reps each side)",
+        category: .mobility,
+        suggestedDurationSeconds: 120,
+        gtgFriendly: true,
+        blocks: [
+            MicrodoseBlock(
+                movementId: "shoulder_cars",
+                movementStyle: .none,
+                durationHintSeconds: 120,
+                metrics: [
+                    .reps(
+                        key: "reps_per_side",
+                        defaultValue: 3,
+                        min: 2,
+                        max: 5,
+                        step: 1,
+                        progressable: false
+                    )
+                ]
+            )
+        ]
+    )
+
+    return Catalog(movements: movements, microdoses: microdoses)
+}
+
+// MARK: - Catalog Validation
+
+extension Catalog {
+    /// Validate the catalog for consistency and completeness
+    ///
+    /// Returns a list of validation errors, or empty array if valid.
+    public func validate() -> [String] {
+        var errors: [String] = []
+
+        // Check for duplicate IDs (already guaranteed by Dictionary, but check for empty IDs)
+        for (id, movement) in movements {
+            if id.isEmpty || movement.id.isEmpty {
+                errors.append("Movement has empty ID")
+            }
+            if id != movement.id {
+                errors.append("Movement key '\(id)' doesn't match movement.id '\(movement.id)'")
+            }
+            if movement.name.isEmpty {
+                errors.append("Movement '\(id)' has empty name")
+            }
+        }
+
+        for (id, definition) in microdoses {
+            if id.isEmpty || definition.id.isEmpty {
+                errors.append("Microdose definition has empty ID")
+            }
+            if id != definition.id {
+                errors.append("Microdose key '\(id)' doesn't match definition.id '\(definition.id)'")
+            }
+            if definition.name.isEmpty {
+                errors.append("Microdose '\(id)' has empty name")
+            }
+            if definition.blocks.isEmpty {
+                errors.append("Microdose '\(id)' has no blocks")
+            }
+
+            // Check that all referenced movements exist
+            for block in definition.blocks {
+                if !movements.keys.contains(block.movementId) {
+                    errors.append("Microdose '\(id)' references non-existent movement '\(block.movementId)'")
+                }
+
+                // Validate metrics
+                for metric in block.metrics {
+                    switch metric {
+                    case .reps(_, let defaultValue, let min, let max, _, _):
+                        if defaultValue < min {
+                            errors.append("Microdose '\(id)': default reps \(defaultValue) < min \(min)")
+                        }
+                        if defaultValue > max {
+                            errors.append("Microdose '\(id)': default reps \(defaultValue) > max \(max)")
+                        }
+                        if min > max {
+                            errors.append("Microdose '\(id)': min reps \(min) > max \(max)")
+                        }
+                    case .band(_, let defaultValue, _):
+                        if defaultValue.isEmpty {
+                            errors.append("Microdose '\(id)': band metric has empty default")
+                        }
+                    }
+                }
+            }
+        }
+
+        // Check that we have at least one microdose in each category
+        let hasVO2 = microdoses.values.contains { $0.category == .vo2 }
+        let hasGTG = microdoses.values.contains { $0.category == .gtg }
+        let hasMobility = microdoses.values.contains { $0.category == .mobility }
+
+        if !hasVO2 {
+            errors.append("Catalog has no VO2 microdoses")
+        }
+        if !hasGTG {
+            errors.append("Catalog has no GTG microdoses")
+        }
+        if !hasMobility {
+            errors.append("Catalog has no Mobility microdoses")
+        }
+
+        return errors
+    }
+}