refactor!: drop six runtime dependencies

[Halvanhelv]

Summary

The gemspec declared eight runtime dependencies. Six of them are never loaded by this gem. After this change it loads two: ox and punkt-segmenter.

That is what the README promised all along — "This dependencies are not included, as you might need to roll your own cache based on different store" — the gemspec just never agreed with it.

What was actually used

gem	where its constant appears in lib/	verdict
ox	Ox::Sax, Ox.sax_parse in the tokenizer	kept
punkt-segmenter	Punkt::SentenceTokenizer in the tokenizer	kept
dry-initializer	five extend lines	dropped
connection_pool	nowhere — the pool is duck typed on #with	dropped
redis	nowhere — bare Redis is never named	dropped
deepl-rb	nowhere — require "deepl" at load, constant unused	dropped
redis-namespace	inside one method body of RedisCacheStore	dropped
ratelimit	inside one method body of RedisRateLimiter	dropped

The last two already resolved lazily: they are named inside method bodies, so the gem loaded fine without them and only broke if you actually used those classes. Declaring them as hard runtime dependencies forced them on everyone who used their own cache store.

dry-initializer → plain Ruby

Dry::Initializer generated private readers, so replacing them with a private attr_reader keeps the public API byte-for-byte identical:

# before
extend Dry::Initializer
param :values
option :limit, default: proc { MAX_CHUNK_SIZE }

# after
def initialize(values, limit: MAX_CHUNK_SIZE, count_limit: COUNT_LIMIT)
  @values = values
  @limit = limit
  @count_limit = count_limit
end

private

attr_reader :values, :limit, :count_limit

Bug fixed on the way

RedisRateLimiter declared threshold and interval as positional params, so the keyword call the README documents silently discarded them:

RedisRateLimiter.new(pool, threshold: 999, interval: 7)
#=> threshold 8000, interval 60

They are keywords now, matching RedisCacheStore. There is a regression test.

Tests

Both Redis wrappers had no tests at all. They have them now — 6 new cases. The stand-ins they use for Redis::Namespace, Ratelimit and the connection pool double as an executable statement of the duck types this gem expects.

Coverage: 94.68% → 97.57% (282/289).

Breaking changes → 2.0.0

• Applications relying on this gem to install the DeepL client, redis, redis-namespace, connection_pool or ratelimit must depend on them directly. The README now says so explicitly and its example requires deepl.
• Callers passing threshold/interval to RedisRateLimiter positionally must switch to keywords.

Test plan

• bundle exec rake test — 34 runs, 44 assertions, 0 failures, on Ruby 4.0.5 and 3.2.4.
• bundle exec rubocop — 0 offenses.
• Gemfile.lock re-resolved: zero matches for dry-initializer, deepl-rb, redis, connection_pool, ratelimit. With none of them installed, require "deepl_diff" loads and DeepLDiff::Tokenizer.tokenize("<b>hi</b>") returns the expected tokens.

https://claude.ai/code/session_01Pda49PcgziFVnibkKKjXRE