# Architecture

Subtitle Tools is a relocatable React application with a framework-independent
TypeScript subtitle model. The parser first applies byte/text and line bounds,
then produces one normalized cue model for SRT, WebVTT and ASS. Operations return
new documents instead of mutating parser state. Serializers are format-specific;
cross-format export deliberately exposes its preservation boundary.

Parsing and timing transformations are synchronous in v0.1 and therefore capped
at 4,000,000 UTF-16 units, 250,000 units per physical line and 100,000 cues. The
editor renders at most 10,000 cue rows and 2,000 issue rows, while validation and
export still cover the complete bounded document. Revision comparison is
index-aligned and linear rather than an unbounded semantic diff.

The optional waveform component uses browser-native media decoding, keeps at
most 2,000 peak buckets and accepts no more than 128 MiB or four decoded hours.
It does not run a codec, speech-recognition model or network service.