Initial commit

Signed-off-by: Thomas Klaehn <thomas.klaehn@perinet.io>
2026-02-10 11:47:49 +01:00
commit c54fa58c35
17 changed files with 1834 additions and 0 deletions
--- a/.dockerignore
+++ b/.dockerignore
@@ -0,0 +1,49 @@
+# Git
+.git
+.gitignore
+
+# Docker
+Dockerfile
+docker-compose.yml
+.dockerignore
+
+# Data directories
+data/
+/data
+
+# Build artifacts
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+zwift-monitor
+
+# Test files
+*_test.go
+testdata/
+
+# IDE
+.idea
+.vscode
+*.swp
+*.swo
+*~
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Documentation
+README.md
+*.md
+
+# Config files (will be mounted)
+config.yaml
+.env
+
+# Logs
+*.log
+
+# State files
+*.json
--- a/.gitignore
+++ b/.gitignore
@@ -0,0 +1,49 @@
+# Binaries
+zwift-monitor
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Data directories
+data/
+/data
+
+# Config files with credentials
+config.yaml
+.env
+
+# State files
+*.json
+!go.mod
+!go.sum
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool
+*.out
+
+# Dependency directories
+vendor/
+
+# Go workspace file
+go.work
+
+# IDE
+.idea
+.vscode
+*.swp
+*.swo
+*~
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Logs
+*.log
+
+# Token cache
+.zwift-token.json
--- a/51
+++ b/51
@@ -0,0 +1,51 @@
+# Build stage
+FROM golang:1.25-alpine AS builder
+
+WORKDIR /app
+
+# Install build dependencies
+RUN apk add --no-cache git ca-certificates tzdata
+
+# Copy go mod files
+COPY go.mod go.sum ./
+RUN go mod download
+
+# Copy source code
+COPY . .
+
+# Build the binary
+RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o zwift-monitor .
+
+# Final stage
+FROM alpine:latest
+
+# Install runtime dependencies
+RUN apk --no-cache add ca-certificates tzdata
+
+WORKDIR /app
+
+# Copy binary from builder
+COPY --from=builder /app/zwift-monitor .
+
+# Create data directory
+RUN mkdir -p /data/activities
+
+# Run as non-root user
+RUN addgroup -S appgroup && adduser -S appuser -G appgroup
+RUN chown -R appuser:appgroup /app /data
+USER appuser
+
+# Set default environment variables
+ENV ZWIFT_OUTPUT_DIR=/data/activities \
+    ZWIFT_STATE_FILE=/data/zwift-state.json \
+    ZWIFT_TOKEN_CACHE=/data/.zwift-token.json \
+    ZWIFT_POLL_INTERVAL=5m \
+    ZWIFT_LOG_LEVEL=info \
+    ZWIFT_RATE_LIMIT=5 \
+    ZWIFT_MAX_RETRIES=3
+
+# Expose volume for data
+VOLUME ["/data"]
+
+# Run the service
+CMD ["/app/zwift-monitor"]
--- a/README.md
+++ b/README.md
@@ -0,0 +1,337 @@
+# Zwift Activity Monitor
+
+Automatic monitoring service that continuously watches for new Zwift activities and downloads their FIT files.
+
+## Features
+
+- ✅ **Continuous Monitoring**: Automatically checks for new activities every 5 minutes (configurable)
+- ✅ **Automatic Downloads**: Downloads FIT files for new activities as soon as they're available
+- ✅ **Docker Support**: Easy deployment with Docker and Docker Compose
+- ✅ **Persistent State**: Tracks downloaded activities to prevent duplicates
+- ✅ **Rate Limiting**: Respects API rate limits with built-in throttling
+- ✅ **Graceful Shutdown**: Handles SIGTERM/SIGINT for clean container restarts
+- ✅ **Structured Logging**: JSON logging with configurable levels
+- ✅ **Retry Logic**: Automatic retry with exponential backoff for transient failures
+
+## Quick Start
+
+### Using Docker Compose (Recommended)
+
+1. **Clone the repository**
+   ```bash
+   git clone <your-repo-url>
+   cd zwift
+   ```
+
+2. **Create environment file**
+   ```bash
+   cat > .env <<EOF
+   ZWIFT_USERNAME=your@email.com
+   ZWIFT_PASSWORD=yourpassword
+   TZ=Europe/Berlin
+   EOF
+   ```
+
+3. **Create data directory**
+   ```bash
+   mkdir -p data/activities
+   ```
+
+4. **Start the service**
+   ```bash
+   docker-compose up -d
+   ```
+
+5. **View logs**
+   ```bash
+   docker-compose logs -f
+   ```
+
+6. **Check downloaded files**
+   ```bash
+   ls -lh data/activities/
+   ```
+
+### Using Docker
+
+```bash
+docker build -t zwift-monitor .
+
+docker run -d \
+  --name zwift-monitor \
+  --restart unless-stopped \
+  -e ZWIFT_USERNAME=your@email.com \
+  -e ZWIFT_PASSWORD=yourpassword \
+  -e TZ=Europe/Berlin \
+  -v $(pwd)/data:/data \
+  zwift-monitor
+```
+
+### Local Development
+
+```bash
+# Install dependencies
+go mod download
+
+# Set credentials
+export ZWIFT_USERNAME=your@email.com
+export ZWIFT_PASSWORD=yourpassword
+export ZWIFT_OUTPUT_DIR=./data/activities
+export ZWIFT_STATE_FILE=./data/state.json
+
+# Run the service
+go run .
+```
+
+## Configuration
+
+### Environment Variables
+
+| Variable | Default | Description |
+|----------|---------|-------------|
+| `ZWIFT_USERNAME` | *required* | Your Zwift email address |
+| `ZWIFT_PASSWORD` | *required* | Your Zwift password |
+| `ZWIFT_OUTPUT_DIR` | `/data/activities` | Directory for FIT files |
+| `ZWIFT_STATE_FILE` | `/data/zwift-state.json` | State persistence file |
+| `ZWIFT_TOKEN_CACHE` | `/data/.zwift-token.json` | OAuth token cache |
+| `ZWIFT_POLL_INTERVAL` | `5m` | How often to check for new activities |
+| `ZWIFT_RATE_LIMIT` | `5` | Maximum requests per second |
+| `ZWIFT_MAX_RETRIES` | `3` | Number of retries for failed requests |
+| `ZWIFT_LOG_LEVEL` | `info` | Logging level (debug, info, warn, error) |
+| `ZWIFT_LOG_FILE` | `` | Optional log file path |
+| `TZ` | `UTC` | Timezone for timestamps |
+
+### Configuration File (Optional)
+
+You can also use a `config.yaml` file:
+
+```yaml
+username: your@email.com
+password: yourpassword
+output_dir: /data/activities
+poll_interval: 5m
+rate_limit: 5
+max_retries: 3
+log_level: info
+```
+
+Place the config file:
+- Local: `config.yaml` in the project directory
+- Docker: Mount as `/app/config.yaml`
+
+**Note**: Environment variables take precedence over config file values.
+
+## File Naming
+
+Downloaded FIT files are named using the format:
+```
+{activityID}_{date}_{activity-name}.fit
+```
+
+Example:
+```
+12345678_2025-02-10_Morning-Ride.fit
+```
+
+## Logging
+
+The service uses structured logging with the following levels:
+
+- **DEBUG**: Detailed API calls and responses
+- **INFO**: Normal operation, downloads, statistics
+- **WARN**: Retries, non-fatal errors
+- **ERROR**: Failed downloads, authentication issues
+
+### Example Log Output
+
+```
+2025-02-10T10:00:00Z  INFO  Starting Zwift Activity Monitor  poll_interval=5m0s output_dir=/data/activities
+2025-02-10T10:00:01Z  INFO  Loaded state  total_downloaded=42 last_check=2025-02-10T09:55:00Z
+2025-02-10T10:00:02Z  INFO  Running initial check...
+2025-02-10T10:00:03Z  INFO  Checking for new activities...
+2025-02-10T10:00:05Z  INFO  Found new activities  count=1
+2025-02-10T10:00:06Z  INFO  Downloading activity  activity_id=12345678 name="Morning Ride"
+2025-02-10T10:00:08Z  INFO  Successfully downloaded activity  activity_id=12345678 filepath=/data/activities/12345678_2025-02-10_Morning-Ride.fit
+2025-02-10T10:00:08Z  INFO  Download complete  downloaded=1 total_new=1
+```
+
+## State Management
+
+The service maintains a JSON state file (`zwift-state.json`) that tracks:
+- All downloaded activity IDs
+- Activity metadata (name, date, file path)
+- Last check timestamp
+- Total downloads
+
+### Example State File
+
+```json
+{
+  "downloaded_activities": {
+    "12345678": {
+      "id": 12345678,
+      "name": "Morning Ride",
+      "date": "2025-02-10T08:30:00Z",
+      "file_path": "/data/activities/12345678_2025-02-10_Morning-Ride.fit",
+      "downloaded_at": "2025-02-10T10:00:08Z",
+      "sport_type": "cycling"
+    }
+  },
+  "last_check": "2025-02-10T10:00:08Z",
+  "total_downloaded": 1
+}
+```
+
+This state file ensures:
+- No duplicate downloads after restarts
+- Resume capability after crashes
+- Historical tracking of all downloads
+
+## Troubleshooting
+
+### Authentication Fails
+
+```
+ERROR  Failed to create service  error="failed to create Zwift client: ..."
+```
+
+**Solution**: Verify your Zwift credentials are correct.
+
+### No New Activities Detected
+
+```
+INFO  No new activities found
+```
+
+**Possible causes**:
+- No new activities since last check
+- Activities already downloaded
+- Activity privacy settings
+
+**Check**: View your state file to see what's already downloaded:
+```bash
+cat data/zwift-state.json | jq .
+```
+
+### Rate Limiting Issues
+
+```
+WARN  Rate limited by Zwift API
+```
+
+**Solution**: Increase the poll interval:
+```bash
+ZWIFT_POLL_INTERVAL=10m  # Check every 10 minutes instead of 5
+```
+
+### Disk Space Issues
+
+```
+ERROR  Failed to save FIT file  error="no space left on device"
+```
+
+**Solution**: Free up disk space or mount a larger volume.
+
+## Docker Commands
+
+```bash
+# View logs
+docker-compose logs -f
+
+# Restart service
+docker-compose restart
+
+# Stop service
+docker-compose down
+
+# Rebuild after code changes
+docker-compose up -d --build
+
+# View container stats
+docker stats zwift-monitor
+
+# Access container shell
+docker-compose exec zwift-monitor sh
+
+# Check state file
+docker-compose exec zwift-monitor cat /data/zwift-state.json
+```
+
+## Building from Source
+
+```bash
+# Build binary
+go build -o zwift-monitor .
+
+# Run tests (when available)
+go test ./...
+
+# Build Docker image
+docker build -t zwift-monitor .
+
+# Cross-compile for different platforms
+GOOS=linux GOARCH=amd64 go build -o zwift-monitor-linux-amd64
+GOOS=darwin GOARCH=arm64 go build -o zwift-monitor-darwin-arm64
+```
+
+## Architecture
+
+```
+zwift/
+├── main.go                      # Entry point with signal handling
+├── internal/
+│   ├── service/                 # Main service loop
+│   │   └── service.go          # Ticker-based monitoring
+│   ├── monitor/                 # Activity monitoring logic
+│   │   └── monitor.go          # Check and download orchestration
+│   ├── client/                  # Zwift API client
+│   │   ├── client.go           # API wrapper with rate limiting
+│   │   └── auth.go             # OAuth token management
+│   ├── state/                   # State persistence
+│   │   └── state.go            # Thread-safe JSON state
+│   ├── storage/                 # File system operations
+│   │   └── storage.go          # Atomic FIT file writes
+│   └── config/                  # Configuration management
+│       └── config.go           # Env vars + YAML loading
+└── Dockerfile                   # Multi-stage Docker build
+```
+
+## Security Considerations
+
+- **Credentials**: Never commit credentials to git. Use environment variables or Docker secrets.
+- **Token Cache**: Stored with 0600 permissions (owner read/write only).
+- **State File**: Contains activity IDs but no sensitive data.
+- **Container**: Runs as non-root user for security.
+
+## API Usage
+
+This service uses the unofficial Zwift API via the [gravl](https://github.com/bzimmer/gravl) library. The API:
+
+- Is not officially supported by Zwift
+- May change without notice
+- Requires regular Zwift credentials (no special API key needed)
+- Respects rate limiting (5 requests/second by default)
+
+## License
+
+[Your License Here]
+
+## Contributing
+
+Contributions welcome! Please:
+1. Fork the repository
+2. Create a feature branch
+3. Make your changes
+4. Submit a pull request
+
+## Support
+
+For issues or questions:
+- Create an issue in the repository
+- Check existing issues for similar problems
+- Include logs and configuration (redact credentials!)
+
+## Acknowledgments
+
+- [gravl](https://github.com/bzimmer/gravl) - Go library for Zwift API
+- [Zwift](https://zwift.com) - Virtual cycling platform
--- a/config.example.yaml
+++ b/config.example.yaml
@@ -0,0 +1,22 @@
+# Zwift Activity Monitor Configuration
+# Copy this file to config.yaml and fill in your credentials
+
+# Authentication (prefer environment variables for security)
+username: ""  # Or set ZWIFT_USERNAME
+password: ""  # Or set ZWIFT_PASSWORD
+
+# Storage paths
+output_dir: /data/activities          # Directory for FIT files
+state_file: /data/zwift-state.json    # State persistence file
+token_cache: /data/.zwift-token.json  # OAuth token cache
+
+# Monitoring configuration
+poll_interval: 5m  # How often to check for new activities (e.g., 5m, 10m, 1h)
+
+# API configuration
+rate_limit: 5     # Maximum requests per second to Zwift API
+max_retries: 3    # Number of retries for failed API calls
+
+# Logging configuration
+log_level: info   # Logging level: debug, info, warn, error
+log_file: ""      # Optional: path to log file (empty = stdout only)
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -0,0 +1,39 @@
+version: '3.8'
+
+services:
+  zwift-monitor:
+    build: .
+    container_name: zwift-monitor
+    restart: unless-stopped
+    environment:
+      # Required: Zwift credentials (use .env file or set directly)
+      - ZWIFT_USERNAME=${ZWIFT_USERNAME}
+      - ZWIFT_PASSWORD=${ZWIFT_PASSWORD}
+
+      # Optional: Monitoring configuration
+      - ZWIFT_POLL_INTERVAL=${ZWIFT_POLL_INTERVAL:-5m}
+      - ZWIFT_LOG_LEVEL=${ZWIFT_LOG_LEVEL:-info}
+
+      # Optional: API configuration
+      - ZWIFT_RATE_LIMIT=${ZWIFT_RATE_LIMIT:-5}
+      - ZWIFT_MAX_RETRIES=${ZWIFT_MAX_RETRIES:-3}
+
+      # Optional: Timezone (adjust to your timezone)
+      - TZ=${TZ:-Europe/Berlin}
+    volumes:
+      # Persistent storage for FIT files and state
+      - ./data:/data
+
+      # Optional: Mount custom config file
+      # - ./config.yaml:/app/config.yaml:ro
+    logging:
+      driver: "json-file"
+      options:
+        max-size: "10m"
+        max-file: "3"
+    healthcheck:
+      test: ["CMD", "test", "-f", "/data/zwift-state.json"]
+      interval: 1m
+      timeout: 10s
+      retries: 3
+      start_period: 30s
--- a/go.mod
+++ b/go.mod
@@ -0,0 +1,43 @@
+module zwift-activity-loader
+
+go 1.25.6
+
+require (
+	github.com/bzimmer/activity v0.10.0 // indirect
+	github.com/bzimmer/gravl v0.10.0 // indirect
+	github.com/bzimmer/httpwares v0.1.3 // indirect
+	github.com/cpuguy83/go-md2man/v2 v2.0.4 // indirect
+	github.com/fsnotify/fsnotify v1.9.0 // indirect
+	github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
+	github.com/hashicorp/go-immutable-radix v1.0.0 // indirect
+	github.com/hashicorp/go-metrics v0.5.3 // indirect
+	github.com/hashicorp/golang-lru v0.5.0 // indirect
+	github.com/martinlindhe/unit v0.0.0-20230420213220-4adfd7d0a0d6 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
+	github.com/rs/zerolog v1.33.0 // indirect
+	github.com/russross/blackfriday/v2 v2.1.0 // indirect
+	github.com/sagikazarmark/locafero v0.11.0 // indirect
+	github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 // indirect
+	github.com/spf13/afero v1.15.0 // indirect
+	github.com/spf13/cast v1.10.0 // indirect
+	github.com/spf13/pflag v1.0.10 // indirect
+	github.com/spf13/viper v1.21.0 // indirect
+	github.com/subosito/gotenv v1.6.0 // indirect
+	github.com/twpayne/go-geom v1.5.4 // indirect
+	github.com/twpayne/go-gpx v1.3.1 // indirect
+	github.com/twpayne/go-polyline v1.1.1 // indirect
+	github.com/urfave/cli/v2 v2.27.2 // indirect
+	github.com/xrash/smetrics v0.0.0-20240312152122-5f08fbb34913 // indirect
+	go.uber.org/multierr v1.10.0 // indirect
+	go.uber.org/zap v1.27.1 // indirect
+	go.yaml.in/yaml/v3 v3.0.4 // indirect
+	golang.org/x/net v0.25.0 // indirect
+	golang.org/x/oauth2 v0.35.0 // indirect
+	golang.org/x/sync v0.16.0 // indirect
+	golang.org/x/sys v0.29.0 // indirect
+	golang.org/x/text v0.28.0 // indirect
+	golang.org/x/time v0.14.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
--- a/go.sum
+++ b/go.sum
@@ -0,0 +1,175 @@
+github.com/DataDog/datadog-go v3.2.0+incompatible/go.mod h1:LButxg5PwREeZtORoXG3tL4fMGNddJ+vMq1mwgfaqoQ=
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+golang.org/x/time v0.14.0 h1:MRx4UaLrDotUKUdCIqzPC48t1Y9hANFKIRpNx+Te8PI=
+golang.org/x/time v0.14.0/go.mod h1:eL/Oa2bBBK0TkX57Fyni+NgnyQQN4LitPmob2Hjnqw4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
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+gopkg.in/yaml.v2 v2.2.5/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
--- a/internal/client/auth.go
+++ b/internal/client/auth.go
@@ -0,0 +1,90 @@
+package client
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	"golang.org/x/oauth2"
+)
+
+// TokenCache handles token persistence
+type TokenCache struct {
+	filePath string
+}
+
+// NewTokenCache creates a new token cache
+func NewTokenCache(filePath string) *TokenCache {
+	return &TokenCache{filePath: filePath}
+}
+
+// Load loads a token from cache
+func (tc *TokenCache) Load() (*oauth2.Token, error) {
+	// Check if file exists
+	if _, err := os.Stat(tc.filePath); os.IsNotExist(err) {
+		return nil, nil // No cached token
+	}
+
+	// Read file
+	data, err := os.ReadFile(tc.filePath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read token cache: %w", err)
+	}
+
+	// Unmarshal token
+	var token oauth2.Token
+	if err := json.Unmarshal(data, &token); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal token: %w", err)
+	}
+
+	// Check if token is expired
+	if token.Expiry.Before(time.Now()) {
+		return nil, nil // Token expired
+	}
+
+	return &token, nil
+}
+
+// Save saves a token to cache
+func (tc *TokenCache) Save(token *oauth2.Token) error {
+	// Create directory if it doesn't exist
+	dir := filepath.Dir(tc.filePath)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return fmt.Errorf("failed to create token cache directory: %w", err)
+	}
+
+	// Marshal token
+	data, err := json.MarshalIndent(token, "", "  ")
+	if err != nil {
+		return fmt.Errorf("failed to marshal token: %w", err)
+	}
+
+	// Write to file with restricted permissions
+	if err := os.WriteFile(tc.filePath, data, 0600); err != nil {
+		return fmt.Errorf("failed to write token cache: %w", err)
+	}
+
+	return nil
+}
+
+// Authenticate authenticates with Zwift using username and password
+func Authenticate(ctx context.Context, username, password string, tokenCache *TokenCache) (*oauth2.Token, error) {
+	// Try to load cached token first
+	if tokenCache != nil {
+		token, err := tokenCache.Load()
+		if err == nil && token != nil && token.Valid() {
+			return token, nil
+		}
+	}
+
+	// Authenticate with username/password
+	// Note: The gravl library handles the actual OAuth2 flow
+	// We'll use the credentials directly with the client
+
+	// For now, we'll return nil as the gravl client handles authentication
+	// This function serves as a placeholder for explicit token management
+	return nil, fmt.Errorf("authentication handled by gravl client")
+}
--- a/internal/client/client.go
+++ b/internal/client/client.go
@@ -0,0 +1,125 @@
+package client
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"github.com/bzimmer/activity"
+	"github.com/bzimmer/activity/zwift"
+	"golang.org/x/time/rate"
+)
+
+// Client wraps the Zwift API client with rate limiting and retry logic
+type Client struct {
+	client      *zwift.Client
+	rateLimiter *rate.Limiter
+	maxRetries  int
+	athleteID   int64 // Cached athlete ID
+}
+
+// NewClient creates a new Zwift client
+func NewClient(username, password string, rateLimit, maxRetries int) (*Client, error) {
+	// Create HTTP client
+	httpClient := &http.Client{
+		Timeout: 30 * time.Second,
+	}
+
+	// Create rate limiter (requests per second)
+	limiter := rate.NewLimiter(rate.Limit(rateLimit), rateLimit*2)
+
+	// Create Zwift client with credentials
+	zwiftClient, err := zwift.NewClient(
+		zwift.WithHTTPClient(httpClient),
+		zwift.WithRateLimiter(limiter),
+		zwift.WithTokenRefresh(username, password),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create Zwift client: %w", err)
+	}
+
+	return &Client{
+		client:      zwiftClient,
+		rateLimiter: limiter,
+		maxRetries:  maxRetries,
+	}, nil
+}
+
+// GetProfile gets the authenticated user's profile and caches the athlete ID
+func (c *Client) GetProfile(ctx context.Context) (int64, error) {
+	// Return cached athlete ID if available
+	if c.athleteID != 0 {
+		return c.athleteID, nil
+	}
+
+	// Get profile from Zwift (using "me" as the profile ID)
+	profile, err := c.client.Profile.Profile(ctx, zwift.Me)
+	if err != nil {
+		return 0, fmt.Errorf("failed to get profile: %w", err)
+	}
+
+	// Cache athlete ID
+	c.athleteID = profile.ID
+
+	return profile.ID, nil
+}
+
+// ListRecentActivities lists recent activities for the athlete
+func (c *Client) ListRecentActivities(ctx context.Context, athleteID int64, limit int) ([]*zwift.Activity, error) {
+	// Create pagination spec
+	spec := activity.Pagination{
+		Total: limit,
+	}
+
+	// List activities from Zwift
+	activities, err := c.client.Activity.Activities(ctx, athleteID, spec)
+	if err != nil {
+		return nil, fmt.Errorf("failed to list activities: %w", err)
+	}
+
+	return activities, nil
+}
+
+// DownloadFIT downloads the FIT file for an activity
+func (c *Client) DownloadFIT(ctx context.Context, athleteID, activityID int64) ([]byte, string, error) {
+	// Retry logic
+	var lastErr error
+	for attempt := 0; attempt < c.maxRetries; attempt++ {
+		if attempt > 0 {
+			// Exponential backoff
+			backoff := time.Duration(1<<uint(attempt)) * time.Second
+			select {
+			case <-ctx.Done():
+				return nil, "", ctx.Err()
+			case <-time.After(backoff):
+			}
+		}
+
+		// Export FIT file
+		export, err := c.client.Activity.Export(ctx, activityID)
+		if err != nil {
+			lastErr = err
+			continue
+		}
+
+		// Read data from reader
+		data, err := io.ReadAll(export.Reader)
+		if err != nil {
+			lastErr = err
+			continue
+		}
+
+		// Return data and filename
+		return data, export.Filename, nil
+	}
+
+	return nil, "", fmt.Errorf("failed to download FIT file after %d attempts: %w", c.maxRetries, lastErr)
+}
+
+// Close closes the client
+func (c *Client) Close() error {
+	// Nothing to close for now
+	return nil
+}
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -0,0 +1,123 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/spf13/viper"
+)
+
+// Config holds all configuration for the Zwift monitor service
+type Config struct {
+	// Authentication
+	Username string `mapstructure:"username"`
+	Password string `mapstructure:"password"`
+
+	// Storage
+	OutputDir      string `mapstructure:"output_dir"`
+	StateFile      string `mapstructure:"state_file"`
+	TokenCachePath string `mapstructure:"token_cache"`
+
+	// Monitoring
+	PollInterval time.Duration `mapstructure:"poll_interval"`
+
+	// API Configuration
+	RateLimit  int `mapstructure:"rate_limit"`
+	MaxRetries int `mapstructure:"max_retries"`
+
+	// Logging
+	LogLevel string `mapstructure:"log_level"`
+	LogFile  string `mapstructure:"log_file"`
+}
+
+// Load loads configuration from environment variables and optional config file
+func Load() (*Config, error) {
+	v := viper.New()
+
+	// Set defaults
+	v.SetDefault("output_dir", "/data/activities")
+	v.SetDefault("state_file", "/data/zwift-state.json")
+	v.SetDefault("token_cache", "/data/.zwift-token.json")
+	v.SetDefault("poll_interval", "5m")
+	v.SetDefault("rate_limit", 5)
+	v.SetDefault("max_retries", 3)
+	v.SetDefault("log_level", "info")
+	v.SetDefault("log_file", "")
+
+	// Bind environment variables
+	v.SetEnvPrefix("ZWIFT")
+	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
+	v.AutomaticEnv()
+
+	// Try to load config file if it exists
+	configPaths := []string{
+		"config.yaml",
+		"/app/config.yaml",
+		filepath.Join(os.Getenv("HOME"), ".zwift-monitor.yaml"),
+	}
+
+	for _, path := range configPaths {
+		if _, err := os.Stat(path); err == nil {
+			v.SetConfigFile(path)
+			if err := v.ReadInConfig(); err != nil {
+				return nil, fmt.Errorf("failed to read config file %s: %w", path, err)
+			}
+			break
+		}
+	}
+
+	var cfg Config
+	if err := v.Unmarshal(&cfg); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal config: %w", err)
+	}
+
+	// Validate required fields
+	if err := cfg.Validate(); err != nil {
+		return nil, err
+	}
+
+	// Expand paths (handle ~)
+	cfg.OutputDir = expandPath(cfg.OutputDir)
+	cfg.StateFile = expandPath(cfg.StateFile)
+	cfg.TokenCachePath = expandPath(cfg.TokenCachePath)
+	if cfg.LogFile != "" {
+		cfg.LogFile = expandPath(cfg.LogFile)
+	}
+
+	return &cfg, nil
+}
+
+// Validate checks if required configuration is present
+func (c *Config) Validate() error {
+	if c.Username == "" {
+		return fmt.Errorf("username is required (set ZWIFT_USERNAME environment variable)")
+	}
+	if c.Password == "" {
+		return fmt.Errorf("password is required (set ZWIFT_PASSWORD environment variable)")
+	}
+	if c.PollInterval < time.Minute {
+		return fmt.Errorf("poll_interval must be at least 1 minute")
+	}
+	if c.RateLimit < 1 {
+		return fmt.Errorf("rate_limit must be at least 1")
+	}
+	if c.MaxRetries < 1 {
+		return fmt.Errorf("max_retries must be at least 1")
+	}
+	return nil
+}
+
+// expandPath expands ~ to home directory
+func expandPath(path string) string {
+	if strings.HasPrefix(path, "~") {
+		home, err := os.UserHomeDir()
+		if err != nil {
+			return path
+		}
+		return filepath.Join(home, path[1:])
+	}
+	return path
+}
--- a/internal/monitor/monitor.go
+++ b/internal/monitor/monitor.go
@@ -0,0 +1,149 @@
+package monitor
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"zwift-activity-loader/internal/client"
+	"zwift-activity-loader/internal/state"
+	"zwift-activity-loader/internal/storage"
+
+	"github.com/bzimmer/activity/zwift"
+	"go.uber.org/zap"
+)
+
+// Monitor handles activity monitoring and downloading
+type Monitor struct {
+	client    *client.Client
+	state     *state.State
+	storage   *storage.Storage
+	logger    *zap.Logger
+	athleteID int64 // Cached athlete ID
+}
+
+// New creates a new Monitor instance
+func New(client *client.Client, state *state.State, storage *storage.Storage, logger *zap.Logger) *Monitor {
+	return &Monitor{
+		client:  client,
+		state:   state,
+		storage: storage,
+		logger:  logger,
+	}
+}
+
+// CheckAndDownload checks for new activities and downloads them
+func (m *Monitor) CheckAndDownload(ctx context.Context) error {
+	m.logger.Info("Checking for new activities...")
+
+	// Get athlete ID (cached after first call)
+	if m.athleteID == 0 {
+		athleteID, err := m.client.GetProfile(ctx)
+		if err != nil {
+			return fmt.Errorf("failed to get profile: %w", err)
+		}
+		m.athleteID = athleteID
+		m.logger.Debug("Got athlete profile", zap.Int64("athlete_id", athleteID))
+	}
+
+	// List recent activities (last 100)
+	activities, err := m.client.ListRecentActivities(ctx, m.athleteID, 100)
+	if err != nil {
+		return fmt.Errorf("failed to list activities: %w", err)
+	}
+
+	m.logger.Debug("Listed recent activities", zap.Int("count", len(activities)))
+
+	// Filter new activities
+	newActivities := m.filterNewActivities(activities)
+	if len(newActivities) == 0 {
+		m.logger.Info("No new activities found")
+		if err := m.state.UpdateLastCheck(); err != nil {
+			m.logger.Warn("Failed to update last check time", zap.Error(err))
+		}
+		return nil
+	}
+
+	m.logger.Info("Found new activities", zap.Int("count", len(newActivities)))
+
+	// Download new activities
+	downloaded := 0
+	for _, act := range newActivities {
+		if err := m.downloadActivity(ctx, act); err != nil {
+			m.logger.Error("Failed to download activity",
+				zap.Int64("activity_id", act.ID),
+				zap.String("name", act.Name),
+				zap.Error(err))
+			continue
+		}
+		downloaded++
+	}
+
+	m.logger.Info("Download complete",
+		zap.Int("downloaded", downloaded),
+		zap.Int("total_new", len(newActivities)))
+
+	return nil
+}
+
+// filterNewActivities filters activities that haven't been downloaded yet
+func (m *Monitor) filterNewActivities(activities []*zwift.Activity) []*zwift.Activity {
+	var newActivities []*zwift.Activity
+
+	for _, act := range activities {
+		if !m.state.IsDownloaded(act.ID) {
+			newActivities = append(newActivities, act)
+		}
+	}
+
+	return newActivities
+}
+
+// downloadActivity downloads a single activity
+func (m *Monitor) downloadActivity(ctx context.Context, act *zwift.Activity) error {
+	m.logger.Info("Downloading activity",
+		zap.Int64("activity_id", act.ID),
+		zap.String("name", act.Name),
+		zap.Time("date", act.StartDate.Time))
+
+	// Download FIT file
+	data, filename, err := m.client.DownloadFIT(ctx, m.athleteID, act.ID)
+	if err != nil {
+		return fmt.Errorf("failed to download FIT file: %w", err)
+	}
+
+	m.logger.Debug("Downloaded FIT file",
+		zap.Int64("activity_id", act.ID),
+		zap.String("filename", filename),
+		zap.Int("size_bytes", len(data)))
+
+	// Save to storage
+	filepath, err := m.storage.Save(act.ID, act.Name, act.StartDate.Time, data)
+	if err != nil {
+		return fmt.Errorf("failed to save FIT file: %w", err)
+	}
+
+	// Mark as downloaded in state
+	info := state.ActivityInfo{
+		ID:           act.ID,
+		Name:         act.Name,
+		Date:         act.StartDate.Time,
+		FilePath:     filepath,
+		DownloadedAt: time.Now(),
+		SportType:    act.Sport,
+	}
+
+	if err := m.state.MarkDownloaded(info); err != nil {
+		m.logger.Error("Failed to mark activity as downloaded",
+			zap.Int64("activity_id", act.ID),
+			zap.Error(err))
+		// Don't return error here - file is saved, just state update failed
+	}
+
+	m.logger.Info("Successfully downloaded activity",
+		zap.Int64("activity_id", act.ID),
+		zap.String("name", act.Name),
+		zap.String("filepath", filepath))
+
+	return nil
+}
--- a/internal/service/service.go
+++ b/internal/service/service.go
@@ -0,0 +1,160 @@
+package service
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"zwift-activity-loader/internal/client"
+	"zwift-activity-loader/internal/config"
+	"zwift-activity-loader/internal/monitor"
+	"zwift-activity-loader/internal/state"
+	"zwift-activity-loader/internal/storage"
+
+	"go.uber.org/zap"
+)
+
+// Service represents the main monitoring service
+type Service struct {
+	config  *config.Config
+	client  *client.Client
+	monitor *monitor.Monitor
+	state   *state.State
+	storage *storage.Storage
+	logger  *zap.Logger
+	ticker  *time.Ticker
+	ctx     context.Context
+	cancel  context.CancelFunc
+}
+
+// New creates a new Service instance
+func New(cfg *config.Config, logger *zap.Logger) (*Service, error) {
+	// Create client
+	zwiftClient, err := client.NewClient(cfg.Username, cfg.Password, cfg.RateLimit, cfg.MaxRetries)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create Zwift client: %w", err)
+	}
+
+	// Create storage
+	stor, err := storage.New(cfg.OutputDir)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create storage: %w", err)
+	}
+
+	// Create state
+	st := state.New(cfg.StateFile)
+	if err := st.Load(); err != nil {
+		return nil, fmt.Errorf("failed to load state: %w", err)
+	}
+
+	// Create monitor
+	mon := monitor.New(zwiftClient, st, stor, logger)
+
+	// Create context
+	ctx, cancel := context.WithCancel(context.Background())
+
+	return &Service{
+		config:  cfg,
+		client:  zwiftClient,
+		monitor: mon,
+		state:   st,
+		storage: stor,
+		logger:  logger,
+		ticker:  time.NewTicker(cfg.PollInterval),
+		ctx:     ctx,
+		cancel:  cancel,
+	}, nil
+}
+
+// Run starts the service loop
+func (s *Service) Run() error {
+	s.logger.Info("Starting Zwift Activity Monitor",
+		zap.Duration("poll_interval", s.config.PollInterval),
+		zap.String("output_dir", s.config.OutputDir))
+
+	// Get initial stats
+	totalDownloaded, lastCheck := s.state.GetStats()
+	s.logger.Info("Loaded state",
+		zap.Int("total_downloaded", totalDownloaded),
+		zap.Time("last_check", lastCheck))
+
+	// Run initial check immediately
+	s.logger.Info("Running initial check...")
+	if err := s.runCheck(); err != nil {
+		s.logger.Error("Initial check failed", zap.Error(err))
+	}
+
+	// Start ticker loop
+	for {
+		select {
+		case <-s.ctx.Done():
+			s.logger.Info("Service context cancelled, shutting down")
+			return nil
+
+		case <-s.ticker.C:
+			if err := s.runCheck(); err != nil {
+				s.logger.Error("Check failed", zap.Error(err))
+			}
+		}
+	}
+}
+
+// runCheck runs a single check for new activities
+func (s *Service) runCheck() error {
+	// Recover from panics
+	defer func() {
+		if r := recover(); r != nil {
+			s.logger.Error("Panic recovered in runCheck",
+				zap.Any("panic", r),
+				zap.Stack("stack"))
+		}
+	}()
+
+	// Create context with timeout
+	ctx, cancel := context.WithTimeout(s.ctx, 5*time.Minute)
+	defer cancel()
+
+	// Run check and download
+	return s.monitor.CheckAndDownload(ctx)
+}
+
+// Shutdown gracefully shuts down the service
+func (s *Service) Shutdown() error {
+	s.logger.Info("Shutting down gracefully...")
+
+	// Stop ticker
+	s.ticker.Stop()
+
+	// Cancel context (with timeout for current operation)
+	shutdownCtx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	// Wait for current operation to complete
+	done := make(chan struct{})
+	go func() {
+		s.cancel()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+		s.logger.Info("Service stopped")
+	case <-shutdownCtx.Done():
+		s.logger.Warn("Shutdown timeout, forcing exit")
+	}
+
+	// Save final state
+	if err := s.state.Save(); err != nil {
+		s.logger.Error("Failed to save state on shutdown", zap.Error(err))
+		return err
+	}
+
+	// Close client
+	if err := s.client.Close(); err != nil {
+		s.logger.Error("Failed to close client", zap.Error(err))
+		return err
+	}
+
+	s.logger.Info("Shutdown complete")
+	return nil
+}
--- a/internal/state/state.go
+++ b/internal/state/state.go
@@ -0,0 +1,166 @@
+package state
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+)
+
+// ActivityInfo holds information about a downloaded activity
+type ActivityInfo struct {
+	ID               int64     `json:"id"`
+	Name             string    `json:"name"`
+	Date             time.Time `json:"date"`
+	FilePath         string    `json:"file_path"`
+	DownloadedAt     time.Time `json:"downloaded_at"`
+	SportType        string    `json:"sport_type,omitempty"`
+}
+
+// State manages the persistent state of downloaded activities
+type State struct {
+	DownloadedActivities map[int64]ActivityInfo `json:"downloaded_activities"`
+	LastCheck            time.Time              `json:"last_check"`
+	TotalDownloaded      int                    `json:"total_downloaded"`
+
+	filePath string
+	mu       sync.RWMutex
+}
+
+// New creates a new State instance
+func New(filePath string) *State {
+	return &State{
+		DownloadedActivities: make(map[int64]ActivityInfo),
+		LastCheck:            time.Time{},
+		TotalDownloaded:      0,
+		filePath:             filePath,
+	}
+}
+
+// Load loads state from JSON file
+func (s *State) Load() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	// Check if file exists
+	if _, err := os.Stat(s.filePath); os.IsNotExist(err) {
+		// File doesn't exist, start with empty state
+		return nil
+	}
+
+	// Read file
+	data, err := os.ReadFile(s.filePath)
+	if err != nil {
+		return fmt.Errorf("failed to read state file: %w", err)
+	}
+
+	// Unmarshal JSON
+	if err := json.Unmarshal(data, s); err != nil {
+		// Try to backup corrupted file
+		backupPath := s.filePath + ".backup"
+		_ = os.WriteFile(backupPath, data, 0600)
+		return fmt.Errorf("failed to unmarshal state file (backed up to %s): %w", backupPath, err)
+	}
+
+	return nil
+}
+
+// Save saves state to JSON file
+func (s *State) Save() error {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	// Create directory if it doesn't exist
+	dir := filepath.Dir(s.filePath)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return fmt.Errorf("failed to create state directory: %w", err)
+	}
+
+	// Marshal to JSON
+	data, err := json.MarshalIndent(s, "", "  ")
+	if err != nil {
+		return fmt.Errorf("failed to marshal state: %w", err)
+	}
+
+	// Write to temporary file first (atomic write)
+	tmpFile := s.filePath + ".tmp"
+	if err := os.WriteFile(tmpFile, data, 0600); err != nil {
+		return fmt.Errorf("failed to write temporary state file: %w", err)
+	}
+
+	// Rename temporary file to actual file (atomic operation)
+	if err := os.Rename(tmpFile, s.filePath); err != nil {
+		return fmt.Errorf("failed to rename temporary state file: %w", err)
+	}
+
+	return nil
+}
+
+// IsDownloaded checks if an activity has already been downloaded
+func (s *State) IsDownloaded(activityID int64) bool {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	_, exists := s.DownloadedActivities[activityID]
+	return exists
+}
+
+// MarkDownloaded marks an activity as downloaded
+func (s *State) MarkDownloaded(info ActivityInfo) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.DownloadedActivities[info.ID] = info
+	s.TotalDownloaded++
+	s.LastCheck = time.Now()
+
+	// Save state after marking downloaded
+	return s.save()
+}
+
+// UpdateLastCheck updates the last check timestamp
+func (s *State) UpdateLastCheck() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.LastCheck = time.Now()
+	return s.save()
+}
+
+// GetStats returns statistics about downloaded activities
+func (s *State) GetStats() (totalDownloaded int, lastCheck time.Time) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	return s.TotalDownloaded, s.LastCheck
+}
+
+// save is an internal method that saves without locking (assumes lock is held)
+func (s *State) save() error {
+	// Create directory if it doesn't exist
+	dir := filepath.Dir(s.filePath)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return fmt.Errorf("failed to create state directory: %w", err)
+	}
+
+	// Marshal to JSON
+	data, err := json.MarshalIndent(s, "", "  ")
+	if err != nil {
+		return fmt.Errorf("failed to marshal state: %w", err)
+	}
+
+	// Write to temporary file first (atomic write)
+	tmpFile := s.filePath + ".tmp"
+	if err := os.WriteFile(tmpFile, data, 0600); err != nil {
+		return fmt.Errorf("failed to write temporary state file: %w", err)
+	}
+
+	// Rename temporary file to actual file (atomic operation)
+	if err := os.Rename(tmpFile, s.filePath); err != nil {
+		return fmt.Errorf("failed to rename temporary state file: %w", err)
+	}
+
+	return nil
+}
--- a/internal/storage/storage.go
+++ b/internal/storage/storage.go
@@ -0,0 +1,117 @@
+package storage
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"time"
+)
+
+// Storage handles local file system operations for FIT files
+type Storage struct {
+	outputDir string
+}
+
+// New creates a new Storage instance
+func New(outputDir string) (*Storage, error) {
+	// Create output directory if it doesn't exist
+	if err := os.MkdirAll(outputDir, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create output directory: %w", err)
+	}
+
+	return &Storage{
+		outputDir: outputDir,
+	}, nil
+}
+
+// Save saves a FIT file to the output directory
+func (s *Storage) Save(activityID int64, activityName string, date time.Time, data []byte) (string, error) {
+	// Generate filename
+	filename := s.generateFilename(activityID, activityName, date)
+	filepath := filepath.Join(s.outputDir, filename)
+
+	// Check if file already exists
+	if _, err := os.Stat(filepath); err == nil {
+		return filepath, nil // File already exists, no need to save
+	}
+
+	// Write to temporary file first (atomic write)
+	tmpFile := filepath + ".tmp"
+	if err := os.WriteFile(tmpFile, data, 0644); err != nil {
+		return "", fmt.Errorf("failed to write temporary FIT file: %w", err)
+	}
+
+	// Verify file integrity (non-zero size)
+	if len(data) == 0 {
+		_ = os.Remove(tmpFile)
+		return "", fmt.Errorf("FIT file is empty")
+	}
+
+	// Rename temporary file to actual file (atomic operation)
+	if err := os.Rename(tmpFile, filepath); err != nil {
+		_ = os.Remove(tmpFile)
+		return "", fmt.Errorf("failed to rename temporary FIT file: %w", err)
+	}
+
+	return filepath, nil
+}
+
+// Exists checks if a FIT file already exists for an activity
+func (s *Storage) Exists(activityID int64) bool {
+	// List files in output directory
+	files, err := os.ReadDir(s.outputDir)
+	if err != nil {
+		return false
+	}
+
+	// Check if any file starts with the activity ID
+	prefix := fmt.Sprintf("%d_", activityID)
+	for _, file := range files {
+		if strings.HasPrefix(file.Name(), prefix) {
+			return true
+		}
+	}
+
+	return false
+}
+
+// generateFilename generates a filename for a FIT file
+// Format: {activityID}_{date}_{name}.fit
+func (s *Storage) generateFilename(activityID int64, activityName string, date time.Time) string {
+	// Format date as YYYY-MM-DD
+	dateStr := date.Format("2006-01-02")
+
+	// Sanitize activity name (remove special characters)
+	name := sanitizeFilename(activityName)
+	if name == "" {
+		name = "activity"
+	}
+
+	// Limit name length
+	if len(name) > 50 {
+		name = name[:50]
+	}
+
+	return fmt.Sprintf("%d_%s_%s.fit", activityID, dateStr, name)
+}
+
+// sanitizeFilename removes special characters from filename
+func sanitizeFilename(name string) string {
+	// Replace spaces with dashes
+	name = strings.ReplaceAll(name, " ", "-")
+
+	// Remove special characters (keep alphanumeric, dash, underscore)
+	re := regexp.MustCompile(`[^a-zA-Z0-9_-]`)
+	name = re.ReplaceAllString(name, "")
+
+	// Remove multiple consecutive dashes
+	re = regexp.MustCompile(`-+`)
+	name = re.ReplaceAllString(name, "-")
+
+	// Trim dashes from start and end
+	name = strings.Trim(name, "-")
+
+	return name
+}
--- a/main.go
+++ b/main.go
@@ -0,0 +1,106 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"zwift-activity-loader/internal/config"
+	"zwift-activity-loader/internal/service"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+func main() {
+	// Load configuration
+	cfg, err := config.Load()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to load configuration: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Set up logging
+	logger, err := setupLogger(cfg.LogLevel, cfg.LogFile)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to setup logger: %v\n", err)
+		os.Exit(1)
+	}
+	defer logger.Sync()
+
+	// Create service
+	svc, err := service.New(cfg, logger)
+	if err != nil {
+		logger.Fatal("Failed to create service", zap.Error(err))
+	}
+
+	// Set up signal handling for graceful shutdown
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
+
+	// Start service in goroutine
+	errChan := make(chan error, 1)
+	go func() {
+		errChan <- svc.Run()
+	}()
+
+	// Wait for shutdown signal or error
+	select {
+	case sig := <-sigChan:
+		logger.Info("Received signal", zap.String("signal", sig.String()))
+		if err := svc.Shutdown(); err != nil {
+			logger.Error("Error during shutdown", zap.Error(err))
+			os.Exit(1)
+		}
+	case err := <-errChan:
+		if err != nil {
+			logger.Error("Service error", zap.Error(err))
+			os.Exit(1)
+		}
+	}
+
+	logger.Info("Service exited successfully")
+}
+
+// setupLogger creates a zap logger based on configuration
+func setupLogger(logLevel, logFile string) (*zap.Logger, error) {
+	// Parse log level
+	var level zapcore.Level
+	if err := level.UnmarshalText([]byte(logLevel)); err != nil {
+		level = zapcore.InfoLevel
+	}
+
+	// Create encoder config
+	encoderConfig := zap.NewProductionEncoderConfig()
+	encoderConfig.TimeKey = "time"
+	encoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
+
+	// Create core
+	var core zapcore.Core
+
+	if logFile != "" {
+		// Log to both file and stdout
+		file, err := os.OpenFile(logFile, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+		if err != nil {
+			return nil, fmt.Errorf("failed to open log file: %w", err)
+		}
+
+		fileEncoder := zapcore.NewJSONEncoder(encoderConfig)
+		consoleEncoder := zapcore.NewConsoleEncoder(encoderConfig)
+
+		core = zapcore.NewTee(
+			zapcore.NewCore(fileEncoder, zapcore.AddSync(file), level),
+			zapcore.NewCore(consoleEncoder, zapcore.AddSync(os.Stdout), level),
+		)
+	} else {
+		// Log to stdout only
+		consoleEncoder := zapcore.NewConsoleEncoder(encoderConfig)
+		core = zapcore.NewCore(consoleEncoder, zapcore.AddSync(os.Stdout), level)
+	}
+
+	// Create logger
+	logger := zap.New(core, zap.AddCaller(), zap.AddStacktrace(zapcore.ErrorLevel))
+
+	return logger, nil
+}
--- a/run-local.sh
+++ b/run-local.sh
@@ -0,0 +1,33 @@
+#!/bin/bash
+# Script to run Zwift monitor locally with proper configuration
+
+# Check if credentials are set
+if [ -z "$ZWIFT_USERNAME" ] || [ -z "$ZWIFT_PASSWORD" ]; then
+    echo "Error: ZWIFT_USERNAME and ZWIFT_PASSWORD must be set"
+    echo ""
+    echo "Usage:"
+    echo "  export ZWIFT_USERNAME=your@email.com"
+    echo "  export ZWIFT_PASSWORD=yourpassword"
+    echo "  ./run-local.sh"
+    exit 1
+fi
+
+# Set local paths (relative to current directory)
+export ZWIFT_OUTPUT_DIR="$(pwd)/data/activities"
+export ZWIFT_STATE_FILE="$(pwd)/data/zwift-state.json"
+export ZWIFT_TOKEN_CACHE="$(pwd)/data/.zwift-token.json"
+export ZWIFT_LOG_LEVEL="${ZWIFT_LOG_LEVEL:-info}"
+export ZWIFT_POLL_INTERVAL="${ZWIFT_POLL_INTERVAL:-5m}"
+
+# Create data directory if it doesn't exist
+mkdir -p "$ZWIFT_OUTPUT_DIR"
+
+echo "Starting Zwift Activity Monitor..."
+echo "Output directory: $ZWIFT_OUTPUT_DIR"
+echo "State file: $ZWIFT_STATE_FILE"
+echo "Log level: $ZWIFT_LOG_LEVEL"
+echo "Poll interval: $ZWIFT_POLL_INTERVAL"
+echo ""
+
+# Run the monitor
+./zwift-monitor