Return to the Eastern First Bridge Contextual Translator: A Multilingual Contextual Translation Framework Centered on Source-First Evidence

Method and evaluation-protocol preprint for the Return to the Eastern First Bridge Contextual Translator (FBCT): a source-first multilingual contextual translation framework with four-layer context (segment meaning, internal context, external context, usage scenario) and cross-system mapping-type labels (equivalent / approximate / functional / loanword / non-corresponding). Includes frozen evaluation metrics and a runnable reference skeleton (fbct_ref.py). No measured reproducible-source rates or other empirical numbers are claimed in this Version; filled tables will follow in a New version after the empirical campaign.