Crate structure

trango is a Cargo workspace with six members, all inheriting version, edition, and rust-version from [workspace.package] in the root Cargo.toml.

crates/subtitle (library)

Cue { index, start, end, text, translation } and SubtitleError (see thiserror). parse_srt(&str) -> Result<Vec<Cue>, SubtitleError> parses .srt content (strips a BOM, normalizes line endings), tested against fixtures in crates/subtitle/tests/fixtures/. merge_translation(original, translation) attaches a translation track by timing overlap, not index — each original cue takes the translation cue with the most overlap — since the two tracks may not have matching cue counts (e.g. a hand-timed original paired with an STT-generated translation). No Slint/libmpv dependency.

crates/playback-state (library)

Depends on subtitle. PlaybackMode (Normal | SentenceBySentence, default SentenceBySentence) and MediaSource (Video | Audio, default Video) are independent enums — which source is active and how navigation behaves are separate choices. PlayerState { mode, media_source, cues, current_cue_index, show_translation }; set_mode(mode)/ set_media_source(source) switch directly to either value.

Cue navigation is pure logic returning a SeekCommand/PlaySpanCommand — "what the player should do" — rather than driving mpv directly: next_cue/previous_cue move the cursor and return a command (None at either end); repeat_current_cue never moves the cursor, always returning the same command for the same cue; jump_to_cue(index) backs the sentence list's row clicks, sharing the same command logic so clicks behave exactly like arrow navigation.

format_time(seconds) -> String formats MM:SS/H:MM:SS, clamping non-finite/negative input to 00:00. sync_cue_to_time(time) finds the latest cue starting at-or-before time, driving Normal mode's live sentence tracking (see Video playback).

No I/O, no UI — TDD'd standalone.

crates/word-analysis (library)

Word-by-word sentence analysis, split out the same way for testability without Slint/libmpv. WordEntry/WordAnalysis (entry.rs) is the data model. cache.rs persists analyses to a JSON sidecar (subs.srt → subs.wordanalysis.json), AnalysisCache { model, entries: HashMap<u32, WordAnalysis> } keyed by Cue::index; a missing/corrupt cache loads as empty rather than erroring. ollama.rs's OllamaClient trait (list_models, analyze_sentence) lets tests swap in a fake instead of a real server; HttpOllamaClient talks to http://localhost:11434 via ureq (GET /api/tags, POST /api/generate with stream: false/format: "json"), defensively stripping a ```json fence some models add. Prompt-building and response-parsing are plain functions tested with canned strings; HttpOllamaClient itself is tested against a local mock HTTP server (TcpListener on a random port).

crates/audio-capture (library)

System audio capture for the Audio source (see System audio capture). AudioCapture runs ffmpeg -f pulse as a subprocess (start/stop, the latter asking ffmpeg to quit gracefully via stdin before falling back to killing it), and default_monitor_source asks pactl for the default sink's matching .monitor source. Same external-process-via-Command pattern as subtitle::WhisperCliGenerator, tested against fake shell-script binaries the same way. No Slint/libmpv dependency.

crates/niqud (library)

Hebrew niqud diacritization and a deterministic Latin pronunciation guide, replacing Ollama's unreliable LLM-guessed pronunciation for Hebrew sentences only (see specs.md's "Hebrew pronunciation" entry and ort). hebrew_detect::contains_hebrew gates the whole pipeline per sentence (Unicode block U+0590-U+05FF) — sentences in other languages never invoke it. tokenizer.rs/decode.rs are pure functions (tokenizing, and reconstructing the diacritized string from a model run's logits) tested against fixtures with no model file needed; onnx_client::OnnxNiqudClient ties them to a real ort::Session — Clone, so the loaded model is reused for the process's lifetime rather than per call. No Slint/libmpv dependency, same testability split as word-analysis.

crates/app (binary, package trango)

Ties Slint, libmpv, and the library crates together. Package name trango (binary name), directory crates/app; UI-facing product name is TrangoPlayer.

main.rs initializes tracing, opens the Slint window (app-window.slint), and always calls video_player::VideoPlayer::attach once at startup — even with no CLI video path — because Slint's RenderingSetup notification only ever fires once per window (see Video playback for why this can't be deferred). A CLI video argument starts loading immediately; otherwise the video area stays a placeholder until one is picked via the top bar's "Open" button (open_media_dialog.rs: lists a folder's subfolders/video-or-audio files as rows depending on the active source, auto-matches a same-stem .srt, only file rows are selectable) or a second/third CLI argument (subs.srt, and a translation subs.en.srt merged via subtitle::merge_translation). A subtitle or translation file that can't be read/parsed is logged and skipped rather than blocking video playback.

wire_player_state creates the shared Rc<RefCell<PlayerState>> (UI-thread-only, so no Send/Sync needed) and wires select-mode/toggle-translation to PlayerState's methods, mirroring the result back into AppWindow properties the top bar/translation toggle read directly.

Why six crates instead of one

Splitting subtitle, playback-state, word-analysis, audio-capture, and niqud out of the binary keeps most business logic testable without Slint/libmpv, and keeps files small (CLAUDE.md: aim for ~200 lines/file).