Usage Logging

---
name: usage-logging
description: Consult this skill when implementing usage logging and audit trails.
  Use when implementing audit trails, tracking costs, collecting usage analytics,
  managing session logging. Do not use when simple operations without logging needs.
category: infrastructure
tags:
- logging
- usage
- audit
- metrics
- sessions
- analytics
dependencies: []
tools:
- usage-logger
provides:
  infrastructure:
  - usage-logging
  - session-management
  - audit-trails
  patterns:
  - structured-logging
  - metrics-collection
  - cost-tracking
usage_patterns:
- audit-logging
- cost-tracking
- usage-analytics
- session-management
complexity: beginner
estimated_tokens: 450
progressive_loading: true
modules:
- modules/session-patterns.md
- modules/log-formats.md
---
## Table of Contents

- [Overview](#overview)
- [When to Use](#when-to-use)
- [Core Concepts](#core-concepts)
- [Session Management](#session-management)
- [Log Entry Structure](#log-entry-structure)
- [Quick Start](#quick-start)
- [Initialize Logger](#initialize-logger)
- [Log Operations](#log-operations)
- [Query Usage](#query-usage)
- [Integration Pattern](#integration-pattern)
- [Log Storage](#log-storage)
- [Detailed Resources](#detailed-resources)
- [Exit Criteria](#exit-criteria)


# Usage Logging

## Overview

Session-aware logging infrastructure for tracking operations across plugins. Provides structured JSONL logging with automatic session management for audit trails and analytics.

## When To Use

- Need audit trails for operations
- Tracking costs across sessions
- Building usage analytics
- Debugging with operation history

## When NOT To Use

- Simple operations without logging needs

## Core Concepts

### Session Management

Sessions group related operations:
- Auto-created on first operation
- Timeout after 1 hour of inactivity
- Unique session IDs for tracking

### Log Entry Structure

```json
{
  "timestamp": "2025-12-05T10:30:00Z",
  "session_id": "session_1733394600",
  "service": "my-service",
  "operation": "analyze_files",
  "tokens": 5000,
  "success": true,
  "duration_seconds": 2.5,
  "metadata": {}
}
```
**Verification:** Run the command with `--help` flag to verify availability.

## Quick Start

### Initialize Logger
```python
from leyline.usage_logger import UsageLogger

logger = UsageLogger(service="my-service")
```
**Verification:** Run the command with `--help` flag to verify availability.

### Log Operations
```python
logger.log_usage(
    operation="analyze_files",
    tokens=5000,
    success=True,
    duration=2.5,
    metadata={"files": 10}
)
```
**Verification:** Run the command with `--help` flag to verify availability.

### Query Usage
```python
# Recent operations
recent = logger.get_recent_operations(hours=24)

# Usage summary
summary = logger.get_usage_summary(days=7)
print(f"Total tokens: {summary['total_tokens']}")
print(f"Total cost: ${summary['estimated_cost']:.2f}")

# Recent errors
errors = logger.get_recent_errors(count=10)
```
**Verification:** Run the command with `--help` flag to verify availability.

## Integration Pattern

```yaml
# In your skill's frontmatter
dependencies: [leyline:usage-logging]
```
**Verification:** Run the command with `--help` flag to verify availability.

Standard integration flow:
1. Initialize logger for your service
2. Log operations after completion
3. Query for analytics and debugging

## Log Storage

Default location: `~/.claude/leyline/usage/{service}.jsonl`

```bash
# View recent logs
tail -20 ~/.claude/leyline/usage/my-service.jsonl | jq .

# Query by date
grep "2025-12-05" ~/.claude/leyline/usage/my-service.jsonl
```
**Verification:** Run the command with `--help` flag to verify availability.

## Detailed Resources

- **Session Patterns**: See `modules/session-patterns.md` for session management
- **Log Formats**: See `modules/log-formats.md` for structured formats

## Exit Criteria

- Operation logged with all required fields
- Session tracked for grouping
- Logs queryable for analytics
## Troubleshooting

### Common Issues

**Command not found**
Ensure all dependencies are installed and in PATH

**Permission errors**
Check file permissions and run with appropriate privileges

**Unexpected behavior**
Enable verbose logging with `--verbose` flag