@expo/fingerprint

In production use, @expo/fingerprint does exactly what it promises: generates stable, deterministic hashes of your React Native project state. This is critical for build caching and deciding when OTA updates are safe. The library scans native code, dependencies, and configuration files to detect meaningful changes.

The API is straightforward - primarily `createFingerprintAsync()` with options for customizing what gets hashed. Performance is acceptable for CI environments (typically 2-5 seconds on medium projects), though it does file I/O extensively. Memory footprint stays reasonable even on large monorepos. The library handles missing files gracefully and provides clear error messages when project structure is unexpected.

One gotcha: the fingerprint can change between library versions as hashing logic evolves, so pin your version in CI. The `ignorePaths` option is essential for excluding generated files, but requires manual tuning. Documentation could be better on what exactly gets included in fingerprints by default. No built-in retry logic, but operations are synchronous enough that wrapping with your own retry is straightforward.

In practice, @expo/fingerprint does exactly what it promises: generates consistent hashes of your React Native/Expo project to determine if native rebuilds are needed. The core API is straightforward—`createFingerprintAsync()` returns a structured fingerprint object with sources and hash. Integration into CI/CD pipelines is simple, and the fingerprint generation is reliably deterministic across environments.

The TypeScript support is excellent with well-defined types for `FingerprintResult`, `HashSource`, and options. IDE autocomplete works smoothly, making it easy to explore configuration options like `platforms`, `ignorePaths`, and `hashAlgorithm`. Error messages are generally clear when file access issues occur.

The main pain point is documentation sparseness. While the README covers basic usage, there's limited guidance on advanced scenarios like customizing source selection or debugging fingerprint mismatches. You'll need to read the source code or experiment to understand how different file changes affect fingerprints. The learning curve isn't steep, but better real-world examples would help, especially for monorepo setups or when excluding specific native modules.

The @expo/fingerprint package does exactly what it promises: generates deterministic hashes of your React Native project to detect when native rebuilds are needed. The core API is straightforward—`createFingerprintAsync()` returns a hash and sources array with minimal configuration. TypeScript support is solid with well-defined types for options and return values, making IDE autocomplete helpful when configuring ignore patterns or custom hash sources.

In practice, integrating this into CI/CD pipelines is smooth. The fingerprint accurately detects changes to native dependencies, app.json modifications, and native code alterations. Error messages are generally clear when file access issues occur, though debugging why certain files are included/excluded can require digging into the sources array.

The main pain point is documentation depth. While the README covers basic usage, there's limited guidance on advanced scenarios like custom hash sources, monorepo setups, or interpreting the sources array for debugging. You'll likely need to read the TypeScript definitions or source code for non-trivial use cases. Still, for its core purpose in Expo projects and EAS builds, it's a reliable tool.