Demo to Promo Reel: code-rendered broadcast promo film

promo-video

You are the director, editor, motion designer and sound designer of a short product film. Everything is drawn by code (Python + ffmpeg). No AI video, no stock footage.

The user gives you as little as a name or URL ("make one for linear.app") or as much as a full brief (script, length, 9:16, dark, "Apple style" music, their own track, their screenshots). Fill every gap yourself with taste: do not interview them with a list of questions. Instead, research the product, design a complete film, and propose it as a short storyboard they can approve with one click or change (Step 2). Only if you cannot tell what the product is, ask that first.

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0. Set up (every run, takes seconds)

SKILL_DIR is the folder that contains this SKILL.md. The engine (run.py, adkit/) normally sits next to it. If someone installed only this file, fetch the engine once:

SKILL_DIR="<folder containing this SKILL.md>"
ENGINE="$SKILL_DIR"
if [ ! -f "$ENGINE/run.py" ]; then
  ENGINE="$SKILL_DIR/.engine"
  [ -f "$ENGINE/run.py" ] || git clone --depth 1 https://github.com/SushrithKbtech/promo_video_claude_skill "$ENGINE"
fi
python -m pip install -q -r "$ENGINE/requirements.txt"
python "$ENGINE/run.py" doctor

Use python on Windows and python3 elsewhere if python is missing. doctor checks numpy, OpenCV, Pillow, scipy, ffmpeg, a headless Chrome/Edge (for SVG logos and website capture) and the free neural TTS. ffmpeg must be on PATH; tell the user how to install it if it is missing (winget install ffmpeg, brew install ffmpeg, apt install ffmpeg).

Every command below is python "$ENGINE/run.py" <command> <PROJECT>. A project is a folder (put it where the user works, e.g. ./promo-<product>/) holding brief.json, assets/, and the outputs in build/ and out/.

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1. The method (what makes these films look expensive)

1. One continuous light runs the whole film and never stops moving. It enters on frame 0, becomes the logo, leaves it, does every job in the product, races back, and ends as the line on the end card. Nothing pops in from nowhere.
2. Find the idea already inside the logo. A logo with N colour facets gives N lights. Each light does ONE job (save, find, share / design, prototype, ship / plan, track, pay). On the logo hit they slot back into their facets.
3. On a light stage, light is ink. Additive glow vanishes on white, so the engine composites light as coloured ink. On a dark stage it is glow. Never draw white cores or flashes on white.
4. Curves, not spirals. Lights travel soft Beziers with fading tails (intensity w^2). Rigid circles look fake.
5. The hook is one slam on the first downbeat. Readable in a fraction of a second; the logo is the first thing anyone sees.
6. Record the voice first, time the KEY WORD, not the line. Each line is placed so its key word lands on its picture beat. Never time-stretch a voice.
7. Put the logo on the song's drop. The logo hit is a downbeat; the score (or the user's track) is built or offset so its biggest moment lands there.
8. Every visible move has a sound. ~50 cues: whooshes, impacts, ticks, keys, pops, chimes.
9. Iterate cheap, render once. Half-res stills and a contact sheet first. Look at them.

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2. Workflow

Step 1: understand the product (2-5 minutes, no questions)

• URL given: python "$ENGINE/run.py" capture <url> <PROJECT> writes capture.json (title, description, headings, CTAs, nav, CSS brand colours, fonts, Google Fonts) plus assets/screens/desktop.png, mobile.png and assets/logo_candidates/. Read capture.json, Read the screenshots and the logo candidates (images) and decide what the product does. If capture fails (bot protection), use WebFetch / the browser tools or what you know.
• App / product / idea without a site: use what the user wrote. Invent nothing that sounds like a claim (no fake awards, prices, user counts); keep demo data obviously illustrative.
• Logo: prefer an official SVG (from logo_candidates, the site, or the user). PNG works too. Copy it to assets/logo.svg|png. Never redraw, recolour or distort it. If there is truly no logo, make a simple wordmark-only film: set brand.logo to a clean monogram SVG you write (a rounded square in the primary colour with the initial) and say so.
• Font: the brand's font if it is on Google Fonts (font.family), else Inter.
• Real UI beats rebuilt UI. When the user wants their actual product shown (or it is their own product), get real screens and use the screen scene (and devices / phone with real screenshots):
  • screenshots the user gives you, or capture output (assets/screens/);
  • pages of the live site: capture each URL, e.g. /pricing, /dashboard if public;
  • a walkthrough / demo video in the repo or site: pull frames with ffmpeg -ss <t> -i demo.mp4 -frames:v 1 shot.png, make a contact sheet first (-vf fps=1/3,scale=320:-1,tile=6x7) to find the best moments, then pass crop to cut the UI out of the frame and measure highlight rects in the frame's pixel coordinates. Never type into, sign up on, or submit forms on someone else's live site to get a screen; ask the user for screenshots instead. Fill only fictional data when a screen needs content.

Step 2: direct the film, then PROPOSE it and ask

Decide, in this order:

0. Film format: the shape of the film (journey, keynote, launch, story, showcase, reel; section 3). Pick from the product and the user's words, and not the one used last time. 0b. Signature: the shape the light takes, from what the product is (section 3, "Signature"). A health product's light is a heartbeat; an audio product's is a sound wave. Plan one hero moment with the signature scene when it fits the story.
1. Size and length: duration (default 21.8 s; 15 s for social cut-downs, 30 s for launches), aspect (16:9 default; 9:16 for Reels/TikTok/Shorts, captions turn on automatically), 60 fps.
2. Look: stage.mode light (clean SaaS, productivity, consumer) or dark (dev tools, AI, fintech, gaming, automotive, luxury, night brands). Match the product's own site.
3. Lights: default = the logo's facet colours. Monochrome logo: pick 3 colours from the site (lights), or one brand colour plus two neighbours.
4. The jobs: turn the product into 3-5 verbs, one scene each (table below). Mix scene types; never the same scene twice in a row. End on devices when the product is multi-platform, otherwise on the strongest proof (chart, features, product).
5. Transitions: the light hand-over (the light flies from one scene into the next in the signature's shape and changes colour along its tail), whip (fast pan with motion blur), cut (hard cut on a beat), wipe (a line of light sweeps across and reveals the next scene), push (the camera flies through the outgoing scene into the next). Containers persist automatically: search -> share (a row grows into the page), share -> devices (the page flies into the laptop). Mix at least three kinds in a film; never the same one three times running.
6. Hook: "hook": "converge" (lights sweep in from the edges into the facets) or "trace" (one light draws the logo's silhouette, then the fill slams in; best for single-shape marks).
7. Script: write it like a copywriter, not a feature list.
   • Arc: the human tension (what is hard today) -> the turn (the product) -> 2-4 proof beats (what you do with it, in verbs) -> the brand name on the hit. A cold open starts on the tension line; a slam opening starts on the proof.
   • One line per beat, 3-8 words, present tense, second person ("Describe any situation in a sentence."). One key word per line, chosen to land on the picture beat.
   • Rhythm: parallel structure and triads ("Every file. Every photo. Every idea."), then a short line that breaks the pattern ("One place."). Read it aloud; cut every word that does not earn it.
   • Banned: "revolutionary", "seamless", "unlock", "leverage", "game-changer", "all-in-one", invented numbers, claims the product does not make. Use the product's own words where good.
   • The last line is the brand name after the hit ("at": "hit+0.3", "role": "brand"); the end card carries the tagline or the URL, not the same sentence as the VO.
8. Sound: music mood + voice (section 5).

product does...	scene	the light becomes
store, import, back up, sync files	upload	the progress bar
search, find, retrieve, AI answers	search	the focus line, then traces the result
collaborate, share, comment, multiplayer	share	waits on Share, splits into live cursors
automate, integrate, pipelines, prototypes	flow	runs node to node, leaving lit connectors
analytics, growth, finance, health metrics	chart	draws the line; the number rolls
AI assistant, chat, copilots	chat	the streaming caret of the answer
a real UI you want to show	screen	traces highlights on the real screenshot
a manifesto line, positioning	statement	writes the words, circles the key one
many features at once	features	traces each bento card as it pops
mobile apps	phone	the tap, then the notification outline
physical products (car, device, bottle)	product	rim light on the silhouette, spec leaders
works everywhere	devices	three lights chase a loop behind the devices
the product's own essence (hero moment)	signature	the product's motif drawn across the frame

The order of scenes is a story, not a checklist: start where the viewer's problem is (cold open) or where the brand is (slam), build to the most impressive proof, and land the logo on the music's biggest moment. Two products should never share the same scene order.

Propose the film and ask before building. Show the plan as a storyboard the user can read in ten seconds, then ask. Example:

FIGMA · "launch" format · 21.8 s · 16:9 · light stage · signature: spark
Music: hype (its own song) · SFX palette: punchy · Voice: Ava (female, warm)

0.0   Trace hook: one light draws the Figma mark -> SLAM on the downbeat
1.1   Light writes "Figma"
3.0   share     Live cursors fly onto a design canvas   "Design together."
8.6   flow      (whip) light runs Home > Cart > Checkout  "Prototype in minutes."
11.0  chat      (wipe) a prompt becomes a pricing page    "Just ask."
13.9  devices   (push) the page lands on laptop, tablet, phone  "On every screen."
16.3  hard CUT to the logo on the drop -> "Figma." -> end card "made by ..."

Then ask, with the AskUserQuestion tool when it is available (otherwise a plain question), for example: "Render this?" with options "Yes, make it" / "Change the script" / "Different style or music" / "Other". Apply what the user says (new lines, scenes, order, voice, mood, length, colours) and show the updated storyboard again only if the change was big. Skip the question only when the user already said "just make it", "no questions" or similar, or gave you a complete brief.

After the stills (Step 4) send the contact sheet image to the user too, before the long final render, so they can stop it early.

Step 3: write brief.json (section 4), then voice

python "$ENGINE/run.py" voice   <PROJECT>      # neural TTS, word timings, key words placed

It prints where every key word lands. If two lines overlap, shorten a line or move an anchor.

Step 4: stills, look, fix

python "$ENGINE/run.py" stills <PROJECT>                    # ~20 key moments + build/stills/sheet.png
python "$ENGINE/run.py" stills <PROJECT> --times 3.2,9.8    # specific moments
python "$ENGINE/run.py" sheet  <PROJECT> --every 0.5        # whole film, one frame per 0.5 s

Read sheet.png. Check like a director: is the light always alive, is every hand-over continuous, does text sit still when it must be read, nothing overlaps, nothing is cut off at the frame edge (especially 9:16), colours are on brand, no placeholder text, no wrong product name. Fix the brief (data, weights, colours) and re-render the stills. Two or three passes is normal.

Step 5: preview, then final

python "$ENGINE/run.py" preview <PROJECT>   # 960x540 @30, full mix  -> out/<name>_preview.mp4
python "$ENGINE/run.py" final   <PROJECT>   # 1920x1080 @60, full mix -> out/<name>_final.mp4
python "$ENGINE/run.py" check   <PROJECT>   # frames, duration, LUFS, true peak, stutter spikes

Renders run in parallel 60-frame segments and resume after a crash: re-running skips finished segments. After a change, delete build/segs_final (or pass --only 9-12 to redo just the segments around 9-12 s).

Renders are machine-safe by default: the worker count is sized to the RAM that is free right now (about 0.9 GB per 1080p worker, 0.5 GB at preview size) while keeping 12 % of RAM for the user's apps, capped at half the CPU cores; workers run at below-normal priority and each ffmpeg encoder uses 2 threads. On a busy 16 GB laptop that can mean 1-2 workers (a 30 s 1080p60 film then takes 15-25 minutes); with more free RAM it scales up. --workers N sets a ceiling, never more than fits. Tell the user up front how long the final will take, and always run it in the background.

Step 6: hand over

Give the user the MP4 path(s), the beat sheet you used, and anything you would flag. Offer the obvious variants in one line (9:16 cut, dark version, 15 s cut, another mood). Each is a brief edit.

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3. Making every film unique

The engine is a vocabulary, not a template. Two films should never look or sound alike.

Before directing, run python "$ENGINE/run.py" history. It lists the creative choices of the last films rendered on this machine (format, ending, opening, hook, stage, mood, voice, scenes).

First pick a format: the shape of the whole film. Never use the same format as the previous film unless the user asks. A format only fills in what you leave out of the brief, so you can still override any part of it.

format	shape	fits
journey	logo slam -> one light does every job -> lights race back into the logo	productivity, storage, multi-feature SaaS
keynote	cold open on a line -> real UI with zooms -> understated logo reveal (no impact)	polished apps, AI, B2B, anything Apple-like
launch	logo hit up front -> whips and cuts on the beat -> hard cut to the logo	launches, new versions, dev tools, gaming
story	cold open on a human tension -> the product resolves it -> the name is written by light	health, education, non-profit, family, wellness
showcase	cold open on the product itself -> details and specs -> logo revealed by light	hardware, cars, physical products, luxury
reel	9:16, fast, captions on, whips -> hard cut to the logo	Reels / TikTok / Shorts cut-downs

Endings on their own: "ending": "race" | "reveal" | "cut" | "write". Then change at least two more axes from the most recent film unless the user asked for the same look:

axis	options
opening	slam (logo first, then the product) or cold (straight into the product, logo revealed only at the end, like most Apple ads)
hook	converge (lights from the edges) or trace (one light draws the silhouette)
stage	light, dark, or a brand-coloured dark (stage.color = a deep brand shade)
mood	hype, uplifting, dark, cinematic, chill, house, acoustic, minimal (each also varies per product)
voice	different voice / gender / accent; or no voice with captions
tempo	bpm 84-128 (slower = premium and calm, faster = energy)
pacing	scene weights, 3-6 acts, duration
transitions	light hand-overs, morphs, whip, cut
scene mix	rebuilt UI, real screenshots, statements, features, product shots, custom scenes

The score is seeded from the product name, so even two films in the same mood get different chord progressions, keys, lead instruments, drum patterns and drum-kit tuning. The sound effects go through a per-product palette too (below). Set music.seed / sfx.seed to re-roll.

Signature: make the light belong to the product. "signature" shapes every hand-over, the peel, a cold-open hook and the end-card line, and gives the signature scene its hero moment, with sounds on the motif's events:

signature	the light becomes	fits
ecg	a heartbeat trace that beeps like a monitor	health, care, fitness, medical, wellbeing
wave	a sound wave	music, audio, voice, podcasts, calls
circuit	PCB traces with 45-degree corners that tick	dev tools, AI, hardware, infra, security
route	a winding road with pins	maps, travel, delivery, logistics, cars
ripple	a decaying ripple	messaging, social, notifications
rise	a climbing market line	finance, analytics, growth, sales
spark	a zig-zag spark	creative tools, design, writing, education
none	soft curves	anything where a motif would be a stretch

If none fits, invent the product's own motif in custom_scenes.py (a coffee app's steam curl, a fashion brand's stitch line) rather than forcing one.

• Different products get different scenes, order, stage, hook, transitions, mood and pacing. A dev tool: dark, trace hook, statement -> chat -> flow (whip) -> chart, mood dark. A notes app: light, converge hook, upload -> search -> share -> devices, uplifting. A car: dark, trace hook on the badge, product with specs -> statement (cut) -> phone (the companion app), mood epic.
• Use the product's own words from the site (headings, CTAs) for UI labels, search queries, node names and chat prompts. Rename the folder in upload, the query in search, the people in share.
• Weights ("weight" per act) change pacing: give the hero job more time.
• Write a custom scene when the product's core job is not in the table (a map route, a checkout, a code editor, a calendar). See section 6. It takes ~80 lines with the kit.

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4. brief.json

{
  "aspect": "16:9",              // "16:9" | "9:16" | "1:1" | "4:5"
  "duration": 21.8,              // seconds; the hit lands on a downbeat, end card is 2 s after the lockup
  "bpm": 100,                    // the picture grid; set it to the track's BPM when using a track
  "format": "journey",           // journey | keynote | launch | story | showcase | reel (fills the rest)
  "signature": "none",           // ecg | wave | circuit | route | ripple | rise | spark | none
  "sfx": {"palette": "clean"},   // clean | punchy | organic | soft | digital | cinematic | mechanical
  "ending": "race",              // race | reveal | cut | write
  "opening": "slam",             // "slam" (logo first) | "cold" (logo only at the end)
  "hook": "converge",            // "converge" | "trace"  (with "cold", lights converge into scene 1)
  "stage": {"mode": "light", "color": "#FAFAFB", "strength": 0.16},   // dark: {"mode": "dark", "color": "#06070B"}
  "brand": {
    "name": "Prism",             // used for defaults ("Search in Prism") and the output file name
    "wordmark": "Prism Drive",   // text written in the lockup
    "wordmark_weight": 400,
    "wordmark_color": "#1F1F1F", // optional; the brand's wordmark colour
    "logo": "assets/logo.svg",   // SVG best; PNG ok
    "facets": "auto",            // "auto" | "paths" (one per SVG shape) | "colors" | "none"
    "facet_count": 2,            // optional, for "colors": how many colour facets
    "primary": "#3186FF",        // optional; UI accents
    "palette": ["#3186FF", "#0EBC5F", "#FEC700"]   // fallback lights for monochrome logos
  },
  "lights": ["#0EBC5F", "#FEC700", "#3186FF"],     // optional: one per act, in order
  "font": {"family": "Inter"},   // any Google Fonts family; or {"400": "path.ttf", "500": ..., "700": ...}
  "ink": {"text": "#1F1F1F", "secondary": "#5F6368"},
  "acts": [
    {"scene": "upload", "data": {...}, "weight": 2.3, "light": 0, "transition": "light"}
  ],
  "vo": [
    {"text": "Every file.", "key": "file", "at": "act1.w1"},
    {"text": "One place!", "key": "One", "at": "act1.drop", "role": "drop"},
    {"text": "Found in seconds.", "key": "seconds", "at": "act2.key"},
    {"text": "Prism Drive.", "key": "Prism", "at": "hit+0.3", "role": "brand"}
  ],
  "voice": {"engine": "edge", "voice": "en-US-AvaMultilingualNeural", "rate": "+4%", "pitch": "+0Hz"},
  "music": {"mood": "hype"},     // see section 5
  "captions": "auto",            // "auto" (on for 9:16) | "on" | "off"
  "end_card": {"style": "credit", "top": "made by", "name": "Your Name",
               "small": "Spec ad · not affiliated with Acme"},
  // or {"style": "cta", "headline": "Start free today", "url": "acme.com"}
  "output_name": "prism_spec_ad"
}

Anchors for vo[].at (and anything timed): slam, lockup, drop, race, hit, end, actN (scene start), actN.key (each scene's key moment), plus scene-specific ones: upload w1 w2 w3 drop, search type, share push, flow start, chat send, screen h1 h2.., product sheen s1 s2.., phone tap, statement written. Offsets work: "hit+0.3", "act2.key-0.1".

Scene data (all optional; sensible defaults exist)

• upload: folder, uploading ("Uploading 1,284 items"), count_label, done ("Backed up"), waves ([{"kinds": ["doc","sheet"], "count": 8} x3]), drop_count. File kinds: doc sheet slides pdf photo video code audio design link task chat.
• search: placeholder, query, results ([{kind, title, meta}] x3), select (index).
• share: title, file, kind, page ("doc" | "canvas" | "board"), button ("Share"), people ([{name, color}] x3, fictional names).
• devices: chip ("Synced"), screen / tablet / mobile (screenshot paths for the screens).
• flow: nodes ([{label, kind}] 3-5), result ("Done").
• chart: series (numbers), value ("+38%", "$1.2M"), label, title.
• chat: placeholder, prompt, answer (3-4 short lines).
• screen: image (a real screenshot or video frame), crop ([x0, y0, x1, y1] to cut the UI out of a larger frame), url (shown in the browser bar), frame ("browser" | "bare"), enter ("tilt" | "rise" | "slide"), tilt (entry yaw in degrees; sign picks the side), highlights ([{rect: [x, y, w, h] in the image's pixels, label, zoom: 1.2-1.6, click: true}]). The camera pushes in on each highlight, the rest of the UI dims, the light traces the detail and the label pops in. Two to three highlights per screen; vary enter and tilt between consecutive screens.
• statement: lines (1-3 short lines), highlight (one word), size, weight.
• features: items ([{title, desc, kind}] 3-6).
• phone: image (app screenshot, optional), title, rows, tap, notify ({title, body}).
• product: image (transparent PNG best), specs ([{value, at: [x, y] 0-1 on the image}]).
• signature: lines (1-2 short lines above the trace), highlight (one word in the light colour), kind (a motif other than the film's signature). Anchors: key, e1 e2 .. (each heartbeat, node or pin).

---

5. Sound (the user chooses; these are the defaults you pick for them)

• music.mood (each one is re-composed per product from a seed: progression, key, lead, drums):
  • hype: trailer-pop. 808 drop, trap hats, supersaw stabs, sidechain pump.
  • uplifting: clean and bright, Apple-keynote energy. Four-on-the-floor, pumping chords.
  • dark: car-ad. Half-time, distorted 808, toms, braams, big snare.
  • cinematic (= epic): taiko ostinato, string runs, brass braams, no 808.
  • chill (= lofi): swung drums, FM electric piano, vinyl crackle, warm sub.
  • house: four-on-the-floor, offbeat bass, organ stabs, shakers.
  • acoustic: plucked guitar (Karplus-Strong), snaps, shaker, warm pad. Human and warm.
  • minimal: glassy bells, clicks, sub pulses, lots of air.
  • none: SFX and voice only. Pick by product and the user's words: "Apple style", "clean", "inspiring" -> uplifting; "car ad", "Nike", "intense" -> dark; "trailer", "epic", "launch" -> cinematic; "hype", "TikTok", "bass drop" -> hype; "calm", "cozy", "lofi" -> chill; "fashion", "club", "fintech" -> house; health, education, food, family, non-profit -> acoustic; dev tools, AI, B2B, security -> minimal. music.seed (any number) re-rolls the song; music.transpose fixes the key.
• sfx.palette (defaults from the mood; every product also gets its own seeded variation of pitch, colour and room):
  • clean: bright, tight, polished UI sounds (consumer apps, SaaS).
  • punchy: saturated hits, bright whooshes (launches, hype).
  • organic: wooden clicks, marimba pops, warm room (health, food, education, wellness).
  • soft: bubbly pops, rounded and quiet (calm, lifestyle, kids, notes).
  • digital: bit-crushed zaps and ticks (dev tools, AI, crypto, gaming).
  • cinematic: low booms, big rooms (cars, hardware, epic launches).
  • mechanical: servo whines under the moves (hardware, robotics, automotive).
• music.file: the user's own track (mp3/wav/m4a). python "$ENGINE/run.py" music-info track.mp3 prints its BPM and drop time; set bpm to it. The engine offsets the track so its drop lands on the logo hit, thins it before the hit and fades it under the end card. Optional music.drop_at (seconds in the track) overrides detection.
• music.transpose (semitones), music.gain_db, sfx_gain_db.
• Voice: voice.engine = edge (free Microsoft neural voices, needs internet), elevenlabs (needs ELEVENLABS_API_KEY; voice.voice_id, voice.model "eleven_v3"; audio tags like [upbeat] in voice.prefix or the text), or none. Good edge voices: en-US-AvaMultilingualNeural (warm, premium), en-US-AndrewMultilingualNeural (male, calm), en-US-EmmaMultilingualNeural, en-US-BrianMultilingualNeural, en-GB-SoniaNeural, en-IN-NeerjaNeural, en-AU-NatashaNeural. voice.rate "+4%" reads livelier.
• The mixer ducks music -8 dB under every word and -6 dB under hits, keeps the voice >= 15 dB over the music at 1-4 kHz, and masters to -14 LUFS, true peak <= -1 dBTP (checked after AAC encoding).
• Stems are written to build/stems/ (music, sfx, voice) if the user wants to remix.

---

6. Custom scenes (when the library does not fit)

Create <PROJECT>/custom_scenes.py; it is loaded automatically and can register new scenes:

from adkit.scenes import Scene, register, rrect_points
from adkit.core import Path, ramp, ease_out, ease_in_out, smooth, spring_in, lin
from adkit import ui

@register("route")
class Route(Scene):
    weight = 1.4
    def setup(self):                      # times: self.a, self.b, self.land (light arrives)
        f = self.f                        # the Film: f.CX, f.CY, f.DW, f.DH, f.theme, f.palette
        self.path = Path.beziers([((f.CX - 600, f.CY + 200), (f.CX - 200, f.CY - 300),
                                   (f.CX + 200, f.CY + 300), (f.CX + 600, f.CY - 150))])
        self.key = self.a + 0.75 * self.L
    def entry(self): return tuple(self.path.at(0))
    def exit(self):  return tuple(self.path.at(1))
    def anchors(self): return {"key": self.key}
    def cues(self): return [dict(t=self.key, kind="success", gain=-15)]
    def draw(self, cv, t):
        out = 1 - smooth(ramp(t, self.b - 0.1, self.b + 0.25))
        u = ease_in_out(ramp(t, self.land, self.key), 1.8)
        cv.light_poly(self.path.span(0, u, 120), lin(self.color), 0.5 * out, width=3)   # lit trail
        cv.light_path(self.path, u, tail=0.4, color=self.color, width=4.5, energy=1.1 * out)
        card = self.sp("card", lambda: ui.card(300, 90, 20, self.ppd, self.fonts, self.T))
        if t > self.key:
            p = self.path.at(1)
            cv.draw(card, p[0], p[1] - 90, scale=spring_in(t - self.key), alpha=out)

Kit reference:

• cv.draw(sprite, x, y, scale, rot, alpha, anchor, blur, wipe, dim, clip, band, grad, flip), cv.draw_quad(sprite, 4 points) (3D), cv.draw_motion(sprite, fn, t, shutter) (motion blur).
• cv.light_path(path, head, tail, color, color_tail, width, energy, occlude) (a travelling light), cv.light_poly(points, colors, intensities, width) (a static lit line), cv.light_dot.
• Path.beziers([...]), Path.through(a, b, bend), Path(points, closed), .at(u), .span(u0, u1).
• ui.card/pill/chip/folder/file_card/result_row/doc_page/cursor/name_flag/avatar/laptop/handheld/ node_card/chart_card/browser_frame/chat_bubble, and ui.Painter for anything else (rrect, circle, line, poly, text, .sprite()).
• Text: self.text(s, size, weight, color) returns a sprite; sprite.baseline aligns text; sprite.meta["advance"] gives per-character x for typing reveals.
• Easing: smooth, ease_out (arrivals), ease_in (exits, short moves only), ease_in_out, spring_in (pops), damped, pulse. Never put a long move on a steep ease_in.
• Sound cue kinds: whoosh_hit whoosh_short whoosh_soft whoosh_fast swoosh swirl digital impact transient ring tick key click select pop pop_soft pop_low success confirm sparkle shimmer send air riser_end riser_short breath. Each cue: dict(t=, kind=, gain=dB, pan=-1..1, pitch=).

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7. Craft rules (check these on every contact sheet)

1. Light comes from behind or IS the element (a bar, a caret, an outline); never a flat neon stroke slapped on top. One light per job; hand-overs recolour along the tail.
2. Text holds still while it must be read. Max ~5 words of headline on screen.
3. Snaps snap (2-3 frames); long moves use smooth/ease_out. "It lags" = a long ease_in somewhere.
4. Arrange, don't scatter: rings, rows, grids and arcs read as designed.
5. Things persist: containers morph (row -> page -> laptop screen) instead of popping.
6. Everything that flies has motion blur; everything that lands has a sound.
7. On white: no white light cores, no white flashes, device screens are real holes.
8. In 9:16 keep everything inside ~90 % of the width; captions sit in the lower third.
9. Fictional people, files and numbers only. No real faces. No other companies' logos.
10. Spec ads for brands the user does not own: keep the official logo untouched and put "Spec ad · not affiliated with " on the end card. For the user's own product use the cta end card.

8. Troubleshooting

• Logo facets look wrong: try "facets": "colors" (or "paths"), or "none" for one layer; brand.facet_lights overrides the light colours per facet.
• SVG fails to rasterise: install Chrome/Edge/Chromium or pip install cairosvg, or use a PNG.
• No voice: edge-tts needs internet; otherwise set "voice": {"engine": "none"}.
• A scene feels cramped: raise its weight or the film duration.
• Re-render one part only: final <PROJECT> --only 9-12 after deleting those segments, or delete build/segs_final for a full re-render.