Caption craft · browser-local timing · 2026 · Solo — product framing, test-first timing logic, interaction design, accessibility, responsive verification, production deployment
Breathline
A typographic caption bench that turns one spoken passage into a readable, portable timing score.
The problem
Video editors preparing hand-authored captions often split a spoken passage by feel, estimate whether each cue can be read, then manually translate those breaks into subtitle timing. Breathline makes that editorial loop causal: paste a bounded passage, click before any word to place or remove a cut, adjust the known clip duration, and read a proportional timing tape alongside explicit pace, length, and one-word warnings. The same reviewed score becomes a downloadable or copyable WEBVTT artifact. Copy and media never leave the browser; the app has no account, upload, persistence, analytics SDK, payment path, or transcription claim. Production deployment dpl_ERGJHX1yW27zZvccDQTVEc4w9U61 reached READY before independent Foundry harness checks proved HTTPS markers and the four-step export interaction at the stable production alias.
Architecture
Key decisions
Make cuts the memorable control
Every word is a semantic button; activating one toggles the cue break before it. The red cut rule, timing tape, cue count, rates, warnings, and WEBVTT all update from that one editorial decision.
Allocate time without pretending to hear audio
The deterministic core weights non-whitespace characters and preserves the operator's exact total duration. The interface calls this guidance and asks for review against the actual performance rather than claiming transcription or speech analysis.
Use one asymmetric Configure bench
The composition pairs a ruled-paper cutting desk with a large live score, Georgia display copy, monospaced evidence labels, circular cue folios, and proportional tape. It avoids feature tiles, dashboard cards, and a generic center stack.
Prove a portable outcome over HTTPS
The production golden path replaced the source passage, downloaded a generated WEBVTT, and asserted the visible success receipt. Independent desktop and 390-pixel probes also found no horizontal overflow or console/page errors.