content-hash-cache-pattern

The content-hash-cache-pattern skill provides a mechanism for caching the results of computationally expensive file processing tasks using SHA-256 hashes of file contents as cache keys. Unlike traditional path-based caching, this method ensures that the cache remains valid even if files are moved or renamed, and automatically invalidates entries when the file content changes. By decoupling the caching logic from the core processing functions, it allows developers to maintain pure functions while adding caching as a separate service layer, improving efficiency without introducing side effects or modifying existing code.

This skill features a content-hash-based cache key computation for reliable cache identification, a frozen dataclass structure to represent cache entries, and file-based storage where each cache entry is saved as a JSON file named after the content hash. The service layer wrapper handles cache checks, extraction of data, and writing back to the cache, preserving the single-responsibility principle. Additional features include chunked SHA-256 computation for large files, automatic cache invalidation on content changes, and safe handling of corrupted cache files by treating them as cache misses.

Typical use cases include file processing pipelines for PDFs, images, or text extraction, where repeated processing of the same files is costly. It is especially useful for developers implementing command-line interfaces with optional caching, or for enhancing existing pure functions with caching capabilities without changing their core logic. Target users are Python developers, data engineers, and researchers who need efficient and reliable caching for file-based workflows, particularly in scenarios involving large datasets or repeated data processing operations.