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i18n-rosetta v3.0.0: Per-Pair Translation Architecture

· One min read
Curtis Forbes
Creator of i18n-rosetta

i18n-rosetta v3.0.0 introduces the per-pair translation architecture — the defining feature of the entire system.

What Changed​

Prior versions used a single translation method for all language pairs. v3.0.0 breaks that coupling: each source→target pair can use a different method, model, and quality configuration.

{
  "version": 3,
  "pairs": {
    "en:fr": { "method": "google-translate" },
    "en:ja": { "method": "llm", "model": "google/gemini-2.5-pro" },
    "en:crk": { "methodPlugin": "crk-coached-v1" }
  }
}

Why Per-Pair?​

This architecture exists because one project needed Google Translate for French and a coached FST pipeline for an Indigenous language, running side by side in the same sync command.

Google Translate supports ~130 languages. There are over 7,000. The per-pair system means rosetta can scale to any language — you just need a method that works for that pair.

Other Highlights​

  • Plugin system — Install pre-packaged translation methods from the eval harness
  • Config version 3 — New schema with pair-level overrides
  • Quality tiers — Standard, High, Research, Verified — displayed per pair in status

See the Architecture docs for the full ecosystem design.