Glossary

AppError The central error enum defined in src/error.rs. All fallible operations in the application return Result<T, AppError>.

AsyncGlobalBackoffState The struct that tracks failure streaks and computes jittered exponential backoff delays between API retries.

Bbox Bounding box — a rectangle expressed in PDF page coordinates (x, y, width, height) that describes where a piece of text is positioned on a page. Used by the PDF parser and reconstructor.

CacheKey A composite key of (text, src_lang, tgt_lang) used to look up previously translated sentences in TranslationService’s internal cache.

Cli The struct derived by clap from raw command-line arguments. It is the unvalidated precursor to RuntimeConfig.

Danda (।) The Devanagari sentence-ending punctuation mark, equivalent to a full stop in Latin scripts. TMT’s sentence splitter recognises it as a sentence boundary.

formats::translate_file The top-level dispatch function in src/formats/mod.rs. It inspects the input file extension and routes execution to the correct format handler.

RuntimeConfig The validated configuration struct produced by RuntimeConfig::try_from(&cli). It is the single source of truth for the application’s runtime state and is passed to every subsystem.

Semaphore A tokio::sync::Semaphore used by TranslationService to cap the number of concurrent in-flight API requests to the value specified by --concurrency.

split_sentences The function in src/translate/sentence.rs that divides a text string into sentence fragments on ., !, ?, and ।.

TextBlock A struct produced by the PDF parser that pairs a Bbox with the extracted text string for one text-drawing operator on a PDF page.

TMT API The external HTTP translation service provided by Kathmandu University’s ILPRL lab, accessible at https://tmt.ilprl.ku.edu.np/lang-translate. TMT the CLI tool is a client for this API.

TmtClient The low-level HTTP client in src/tmt/mod.rs that sends TmtRequest objects to the TMT API and parses TmtResponse objects back.

TranslationService The high-level orchestration layer in src/translate/service.rs. It wraps TmtClient and adds sentence splitting, caching, deduplication, and concurrency control.