Paragraph rhythm

Every sentence of the paragraph you are in sits on a faint tint whose colour runs cool → warm with the sentence's effective length. Short, punchy sentences are blue; long, loaded ones are red. Monotony shows up as a paragraph of one colour before you would hear it reading aloud.

The tint is deliberately quiet, a wash behind the words rather than a line under them. Underlines are already taken: Obsidian's spellcheck, Harper and links all draw them, and a sentence that carried all three plus a rhythm rule was unreadable. Style checks tint too, at a stronger alpha, so a cliché inside a long sentence reads as the darker patch on the warmer ground.

Rhythm is not a lens: it stays under whichever lens is on, unless Rhythm tint underneath (Settings → Lenses) is off. The dialogue and accents lenses are the exception and hide it regardless, so that a colour there means one thing.

In Zen Mode

Zen Mode keeps the page plain. Rhythm leaves the text and moves to the margin: one bar per sentence, stacked down from the top of the paragraph you are in, all starting at the same x and growing towards the text with the sentence's tier. The meter reads as the paragraph's shape at a glance, and the words carry no colour at all. Turn rhythm off and the meter goes with it.

Effective length

Raw word count is a poor proxy for how long a sentence feels. The plugin uses

effective length = words + commas + ½ × (polysyllables − expected polysyllables)

— a comma adds a beat, and a sentence heavy with three-syllable words reads longer than its word count. Syllables come from a small estimator that is good enough for bucketing (it under-counts vowel hiatus like po-et; that never moves a sentence more than one tier).

Tiers

Settings → Rhythm tiers chooses 4, 5 or 6 colour steps. The boundaries between tiers are absolute, not relative to the paragraph, so a given colour always means the same length — a paragraph of all-red sentences is genuinely long, not merely longer than its neighbours. Boundaries are tuned for English prose and live in one table (RhythmScale.withTiers).

Sentence splitting

Sentences are split with the platform's Intl.Segmenter, then an abbreviation merger rejoins Mr. Smith, St. Ives, etc. and common Portuguese short forms.

Only the current paragraph

Rhythm is computed for the cursor's paragraph, on docChanged, selectionSet and settings changes, once for both renderings. Work is bounded by the paragraph, never by the note.