@hypit/caption

External components import @hypit/caption. Source uses the @hypit/caption@1 Module identity for shared declarations such as Hidden.

Caption has independent content, timing and presentation structures: CaptionDocument owns display Words, correspondence Units and authored Cues; CaptionTiming locates every Unit; and each rendering family presents those Cues before timed Uses choose how they appear. A Use may begin inside a Cue. It changes presentation without changing that Cue's content or restarting its Unit timing.

CaptionDocument owns displayed words with authored separators, display units, word attributes and complete Cue membership. Every Word belongs to exactly one Unit and every Unit belongs to exactly one Cue, in document order. A Cue may carry one Role. The document contains no Narrative token or Segment identities and no time. CaptionTiming independently owns one complete, flat table of absolute unit boundaries on one Timeline. A domain adapter can produce that timing from speech, SRT/VTT can publish it directly, and authored absolute timing can use the same renderer. Cue membership belongs to the document; visibility envelopes, handoff, layout and motion belong to the selected rendering family.

A rendering family's Track accepts document, timing, timeline, the spatial inputs its renderer actually needs and ordered Use children. Fine takes one placement Frame:

<caption:Hidden id="hidden"/>
<narrative-caption:Timing id="story-captions" document={story.caption}
  binding={story.caption-binding} projection={story-time}/>
<time:Window id="impact-window" timeline={film.timeline} from="12s" for="2s"/>
<caption-fine:Caption id="captions" document={story.caption} timing={story-captions}
  timeline={film.timeline} within={vertical.bounds}>
  <caption-fine:Use style={plain}/>
  <caption-fine:Use role="GUEST" style={guest}/>
  <caption-fine:Use during={demo-window} style={hidden}/>
  <caption-fine:Use during={impact-window} style={impact}/>
</caption-fine:Caption>

Each bounded Use consumes one resolved Window through during. Omitted time means the Use applies to the complete Caption document; it is the deliberate batch-caption form, not an anonymous Timeline Window. Domain adapters must resolve semantic or other domain references to ordinary absolute values before a Caption family consumes them. role filters content independently of time. Later matching Uses replace earlier presentation inside their windows, including a Hidden Style. Separate Tracks remain independent and can intentionally display simultaneous captions.

Rendering-family extension

A family owns its Style, schedule, renderer and Track Surface. It can use ordinary VisualTrack objects or an explicit HTML visual; no central renderer dispatch is required.

The public helpers and Types are in index.ts:

• CaptionStyleIntent carries a family identifier and parameters, or rendering: null for Hidden.
• CaptionProgram is the Track's internal collection of ordered, resolved Uses and referenced Styles. It is not a separate author element. create-caption-uses and append-caption-use assemble it from typed Windows. The Track may export it for its Companion, like Visual and Audio Clips.
• captionUseVisibility(program, index, role, envelope) intersects a Cue envelope with a Use and subtracts later matching windows. Hidden participates even though it renders nothing.
• CaptionTiming retains only timelineId, documentId and complete absolute unit boundaries. Narrative-specific binding and projection belong to @hypit/narrative-caption.

Derive layout and animation from authored Cue content and original timing. Apply Use coverage as a visibility mask. Fine keeps the original Present span and element animations, with separate visibility intervals; changing or briefly hiding a Style does not restart karaoke, typing or motion. A family may define lead/tail, handoff, lines, pages and local states, but it does not split or merge authored Cues. Its resulting visibility stays inside the winning Use window. Empty content produces no drawing.

Word attributes remain on CaptionDocument.words. A structural family can interpret an explicit attribute as a keyword role while retaining complete display/alignment units. Time selection does not split <display|speech> text, and elapsed Cue progress is not a replacement for word timing. The content query helpers for Role and attributes remain here. Narrative Selection-to-unit queries belong to @hypit/narrative-caption; neither defines the Use time language.

See Fine's Surface, schedule and renderer for a concrete implementation. New family behavior belongs in its own project package. The selected family interprets its own Styles; mixed-family dispatch, when useful, is an explicit component responsibility.