docs(prompting): fill gaps — vo-paced reveals, density contract, mount thread, sfx

docs/prompting/capstone.mdx

@@ -85,7 +85,7 @@ Every region pins a different technique, and every technique has a chapter:
 | Region | What it demonstrates | Chapter that teaches it |
 | --- | --- | --- |
 | Type (0:00–0:07) | Per-character code typing; the underline that becomes the wire | [Code animations](/prompting/code-blocks), [Prompt anatomy](/prompting/anatomy) |
-| Mount (0:07–0:14) | The timeline's own vocabulary — tracks, clips, `data-*` labels | [Prompt anatomy](/prompting/anatomy) |
+| Mount (0:07–0:14) | The timeline's own vocabulary — tracks, clips, `data-*` labels | [Vocabulary](/prompting/vocabulary) |
 | Measure (0:14–0:21) | `data-chart` block; the wire as chart baseline (matched motion) | [Data and maps](/prompting/data-and-maps), [Transitions](/prompting/transitions) |
 | Everywhere (0:21–0:28) | `world-map` block; real Lambda / Cloud Run regions | [Data and maps](/prompting/data-and-maps), [Rendering and output](/prompting/rendering-and-output) |
 | Material (0:28–0:39) | Generated clip → HEVC proxy → background removed *before* the speech → the line's keywords slam in word-synced as display text BEHIND the cutout (silhouette occlusion) → lower-third behind the subject | [Media and audio](/prompting/media-and-audio), [Caption styles](/prompting/captions-catalog), [Overlays and lower thirds](/prompting/overlays-and-lower-thirds) |
@@ -123,7 +123,7 @@ What IS new — the part you could not have written after any single chapter —
 - **The persistent elements do the handoffs.** The wire is the trick that makes each region *become* the next — the same line is the typed underline, the chart baseline, the map arc, the waveform, the 3D coil. The chip is a callback threaded through all nine techniques; the ruler makes the film's own medium visible.
 - **One brand file governs every region** ([Design systems](/prompting/design-systems)) — so nine techniques from nine chapters land looking like one designer made them.
 - **One variable scope re-skins all of it** ([Variables and templating](/prompting/variables-and-templating)) — the single-file constraint exists so the chart, the map, the glass, the mural, and the confetti all answer to the same two variables in one `--variables` flag.
-- **One soundtrack paces all of it** ([Media and audio](/prompting/media-and-audio)) — the VO cues every region's reveals, and the same BGM that beds the narration feeds the Rhythm region's beat analysis.
+- **One soundtrack paces all of it** ([Media and audio](/prompting/media-and-audio)) — the VO cues every region's reveals ([pace reveals to the narration](/prompting/media-and-audio#pace-reveals-to-the-narration)), the same BGM that beds the narration feeds the Rhythm region's beat analysis, and one SFX plan rides the visual hits — keystrokes at the open, a whoosh per handoff, ticks on counters and beats, one riser into the render ([sound effects](/prompting/media-and-audio#sound-effects)).
 
 That's the method this guide has been building toward: learn each technique in isolation, then write the prompt whose job is not to invent the pieces but to bind them — shared space, shared spine, shared brand, shared variables, shared clock. A chart, a map, typed markup, processed footage, 3D, glass, a shader seam, a beat grid, seeded confetti: every one traceable to a chapter you've already read. The film is what the glue makes of them — and the glue, like everything else here, is just words in the prompt.
 

docs/prompting/media-and-audio.mdx

@@ -41,6 +41,18 @@ SFX resolve from a small bundled library plus the catalog. Cue them to specific
 
 > Put a soft click on the button press at 0:04.
 
+## Pace reveals to the narration
+
+Once a video has a voice, the voice is the clock. The single highest-leverage audio instruction after choosing the voice is telling the agent that on-screen elements land **on their spoken cues** — the stat appears as the narrator says it, not at some independent time the builder eyeballed. Without this, narration and visuals drift into two parallel tracks that happen to share a file:
+
+> VO-paced reveals: each scene's elements land on their spoken cues; secondary elements keep resolving while the narrator is mid-thought; the scene is complete just as the narration moves on.
+
+The capstone film applies exactly this rule to every region — its Direction block reads:
+
+> VO-paced reveals: each region's elements land on their spoken cues as the camera arrives; secondary elements keep resolving while the camera is present; the region is complete just as the camera accelerates away.
+
+Two practical notes: the agent gets word timings for free (the narration is transcribed with per-word timestamps, the same machinery behind [captions](#captions-and-transcription)), so "on its spoken cue" is a real, executable instruction — and the inverse rule matters just as much: the narration never waits for the visuals. Pace the camera and reveals to the voice, not the voice to the animation.
+
 ## Captions and transcription
 
 Captions come from word-level timestamps. When you generate a voiceover, the timing comes with it; for existing footage, transcription produces the timing (Parakeet by default, with a whisper.cpp fallback). Scaffolding a project from a source video can generate captions from its audio directly.

docs/prompting/visual-specs.mdx

@@ -12,6 +12,14 @@ Every element is a primitive the agent can build directly. Two honest limits:
 - **Organic illustration** (drawn characters, painterly texture) can't be fully carried by text — words underdetermine a drawing. Steer to geometric shape language ("flat rounded-geometric figure, circle head, no facial features"), or generate the artwork (see [When to generate artwork](/prompting/generated-artwork)).
 - **Photographic and live-action content** must be supplied as files — mention the paths explicitly.
 
+## The density contract
+
+A spec tells the builder what each element *is*; a density contract tells it how full every frame must be. The capstone film states it once and every region obeys:
+
+> Density: every region fills three roles — one focal element at display scale, at least two supporting elements on their own cues, and the chrome/wire. Asymmetric compositions; display type ~a tenth of frame width; three depth layers with parallax between them.
+
+That's the whole formula, reusable in any prompt: **one focal + at least two supporting + persistent chrome**, composed asymmetrically (60/40, never one element centered in emptiness), display type around a tenth of the frame width, and at least three depth layers so parallax can sell the space. Supporting elements land on their own cues — a frame that fills all three roles at t=0 is a poster, not a scene. Ask for the contract explicitly when a build keeps coming back sparse: "every scene carries one focal element, two supporting elements on staggered cues, and the persistent chrome" is a sentence a builder can be held to.
+
 ## Two more worked specs
 
 The same density applied to a product-UI piece and a typographic piece — both one-shot from these exact words. Where a builder had to make a judgment call on the first pass, the spec below pins it, which is the editing loop these specs live by: build, see what the words underdetermined, tighten the words.

docs/prompting/vocabulary.mdx

@@ -189,4 +189,15 @@ TTS runs locally via Kokoro (no API key needed). Describe the content and the ag
 "Export as transparent WebM"
 ```
 
+<Note>
+**Capstone thread** — the [Level 7 film](/prompting/capstone)'s Mount region (0:07–0:14) is this page's thesis staged as scenery: the framework's own vocabulary — tracks, clips, `data-*` attributes — becomes the scene itself, because the builder and the viewer share the same words for it.
+</Note>
+
+This is the clause in the [full capstone prompt](/prompting/capstone#the-full-prompt-verbatim) that buys the piece — prompt language you can lift for your own video:
+
+> **Mount (7–14s).** Traveling along the wire: it splits into three parallel track lanes; clip chips slide in along the direction of travel and seat onto the lanes on their spoken cues (audio track chip, video track chip, our protagonist chip among them). Small mono labels (`data-start`, `data-track-index`) tag themselves onto chips as the camera passes. The lanes merge back to one wire as the camera accelerates out.
+
+<video controls muted loop playsinline preload="metadata" src="https://static.heygen.ai/hyperframes-oss/docs/images/prompting/capstone-region-mount.mp4" style={{ borderRadius: "0.5rem", marginTop: "0.75rem" }}></video>
+*That clause, rendered — the region cut from the finished film.*
+
 *Next: [High-fidelity looks](/prompting/visual-specs) — past single words, into full visual specs that carry an entire look.*