Provides atomic file write operations by writing to a temporary file, then renaming to the target path with 0o600 permissions. This prevents partial writes and race conditions when multiple processes or requests write to the same file. The pattern is self-contained and can be extracted for any Node.js project needing safe file updates.

Implements password-based authentication with HMAC-signed session tokens, constant-time password comparison to prevent timing attacks, and Basic Auth header parsing. The module handles session token generation, validation, and expiry, and can be reused in any web application requiring simple yet secure local authentication.

A plugin-based internationalization system with a registry for locale messages, interpolation support, and relative-time formatting. It provides a React context provider (useI18n hook) with SSR-safe hydration. The architecture is decoupled from the application and can be extracted as a standalone i18n library for any React project.

Provides lexical and realpath-based path containment checks to prevent directory traversal attacks. It validates that a given path stays within an allowed root directory, handling symlinks, '..' segments, and cross-platform path separators. This is a reusable security utility for any Node.js application that serves user-accessible files.

Manages a Server-Sent Events (SSE) connection with automatic retry and exponential backoff, handling connection lifecycle, startup errors, and cancel-safe reconnection. It provides a clean interface for consuming real-time event streams and can be reused in any web application that needs resilient SSE consumption.

Parses compaction summary metadata from session files, extracting token counts, cost, and other aggregated statistics. It demonstrates a clean pattern for extracting structured data from semi-structured text blocks and can be adapted for any application that needs to parse summary metadata from log or session files.