Implement SourceControlCacheStore: file-based Rails cache for version control

[Copilot]

Rails cache store that persists entries as version-controllable files, ignoring expiration to enable deterministic builds and shared caching across environments.

Implementation

• Cache store: Inherits ActiveSupport::Cache::Store, stores each entry as SHA256-hashed .key and .value file pairs
• Expiration handling: Strips expiration from deserialized entries to prevent time-based invalidation
• Error handling: File I/O failures return false rather than raising, with StandardError rescue scopes
• Test coverage: 23 specs validating write/read, deletion, expiration ignore, edge cases (nil, booleans, long keys)
• CI: GitHub Actions workflow across Ruby 3.2-3.3 with minimal permissions
• Requirements: Ruby 3.2+ and Rails 7.1+

Usage

# config/application.rb
config.cache_store = :source_control_cache_store, 
  cache_path: Rails.root.join("tmp", "cache")

# Creates deterministic file structure
Rails.cache.write("user:123", {name: "Alice"})
# => tmp/cache/a1b2c3d4...key  (contains "user:123")
# => tmp/cache/a1b2c3d4...value (serialized hash)

# Ignores expiration
Rails.cache.write("key", "value", expires_in: 1.hour)
Rails.cache.read("key")  # Always returns "value", never expires

Design decisions

• SHA256 hashing ensures filesystem safety for arbitrary keys (special chars, long strings)
• Two-file structure enables key inspection without deserialization
• Expiration stripped on read rather than rejected on write to maintain Store interface compatibility

Original prompt

This project is a gem (SourceControlCacheStore) exposing a Rails cache store (compatible with Rails 7.1 and higher) that caches in the following way:

1. Has a directory specific in its store declaration for where files should go
2. Does NOT honor expiration params
3. Hashes each key and uses the hash for filenames
4. Stores two files for each request:

• #{hash}.key - the full key that was used
• #{hash}.value - the full value that was stored

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[nhorton]

@copilot - make this require Ruby 3.2+. Note that it means you need to reduce the CI versions that are tested.

[Copilot]

@copilot - make this require Ruby 3.2+. Note that it means you need to reduce the CI versions that are tested.

Updated to require Ruby 3.2+ and reduced CI matrix to test only Ruby 3.2 and 3.3 in commit 71930ca.