# Prompt Expander

> Use when someone hands you a rough video idea, logline or one-liner and wants a full cinematic prompt, when writing or polishing a Gemini Omni Flash / Google Flow prompt, or when planning a conversational edit of an existing clip. Turns "a lonely astronaut finds a flower" into a complete, generation-ready prompt by deciding every dimension a clip can express.

- Skill: `raphaelbgr/prompt-expander` (Agent Skill, multi-file: 4 files)
- Install (CLI): `npx skillmds@latest add raphaelbgr/prompt-expander`
- Raw SKILL.md: https://api.skillmd.com/api/skills/raphaelbgr/prompt-expander/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: raphaelbgr (https://skillmd.com/u/raphaelbgr)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/raphaelbgr/prompt-expander

---


# Prompt expander

Turn a rough idea into a complete, generation-ready cinematic prompt — by deliberately
deciding **every dimension a clip can express**, then writing only the relevant choices
as natural prose.

Written against **Gemini Omni Flash** in Google Flow (~10s clips with synced audio;
accepts text + reference image/audio/video; supports multi-turn conversational editing).
The dimension model transfers to any video generator; the mechanics in §B of the audio
reference are Omni-specific.

**When to use:** someone hands you a logline and wants it "expanded" · you are writing
or polishing a Flow prompt · you want to edit an existing clip (use the Editing path,
not full expansion).

---

## The dimensions — think through ALL of them

For every prompt, consciously decide each axis, then keep only what serves the idea:

| # | Dimension | Reference |
|---|---|---|
| 1 | **Subject** — who/what, 5–8 specific descriptors | [`subject-action-continuity.md`](references/subject-action-continuity.md) |
| 2 | **Action / physics** — one beat, strong verbs, secondary motion | same |
| 3 | **Setting** — location, era, weather, depth layers | same |
| 4 | **Camera** — shot size, angle, movement, lens | [`visual-language.md`](references/visual-language.md) |
| 5 | **Light & colour** — setup, time of day, palette, film stock | same |
| 6 | **Style & mood** — visual style, tone word, atmosphere | same |
| 7 | **Audio** — dialogue / SFX / ambient / music, or explicit silence | [`audio-and-mechanics.md`](references/audio-and-mechanics.md) |
| 8 | **Beat** — the single emotional moment the clip delivers | [`subject-action-continuity.md`](references/subject-action-continuity.md) |

Read the reference for any axis you are unsure how to fill. **Do not paste the menus
into the prompt** — choose a few options and write prose.

---

## Workflow

1. **Parse** the idea: pull out subject, action, setting, and any stated mood, genre or
   audio.
2. **Classify:** a fresh **generation**, or an **edit** of an existing clip? An edit goes
   to the Editing path below.
3. **Fill the gaps:** for each of the 8 dimensions, choose options that fit the mood.
   Use the defaults table for anything unspecified.
4. **Respect the constraints** (audio reference §B5): one beat per ~10s · always specify
   audio · phrase exclusions positively · do not rely on rendered on-screen text · keep
   references to a few.
5. **Write** the prompt as flowing prose in this order:
   *camera → subject → action → setting → light/style → audio*.
   Add a timestamp breakdown only if there are genuinely 2–3 beats.
6. **Lint** the result — [`veo-prompt-lint`](../veo-prompt-lint/SKILL.md) — and fix any
   ERRORs. If that is unavailable, self-check against the Common mistakes list below.
7. **Present** three things: the prompt block, a short **Levers** list of the assumptions
   you made so they can be tweaked, and 1–2 suggested **conversational edits** for
   iterating.

---

## Sensible defaults (when the user is silent)

| Axis | Default |
|---|---|
| Style | photorealistic, cinematic |
| Camera | slow push-in, eye-level, 50mm, shallow depth of field |
| Light | motivated natural light matched to the setting's time of day |
| Motion | 24fps real-time, natural real-world physics |
| Audio | matching ambient bed + one tied SFX; **no dialogue** unless implied |
| Aspect | 16:9 (9:16 if "shorts / vertical / phone" is implied) |
| Beat | one clear reveal or reaction |

**State the defaults you used in the Levers list.** Never silently bury a consequential
choice.

## Ask vs. assume

Default to assuming and proceeding, noting it in Levers. Ask **only** when a choice is
both consequential and genuinely ambiguous — almost always one of: **realistic vs.
animated/stylised**, **dialogue vs. silent**, **vertical vs. widescreen**. Bundle those
questions; do not drip them one at a time.

---

## Editing path (an existing clip)

Use the surgical rule from the audio reference §B1:

- **One change per turn.** Isolate a single dimension; verify before the next edit.
- **Freeze-list:** name explicitly what stays.
  `Change <X>. Keep the camera, subject, location, timing, and audio identical.`
- **Batch changes as a numbered list**, ending with the same freeze line.
- Remember: editing the *spoken audio* of a clip is currently restricted.

---

## Worked example

**Idea:** "a lonely astronaut finds a flower on a dead planet"

**Expanded prompt:**

> Slow push-in, low-angle medium shot on a weathered astronaut in a scuffed white EVA
> suit, cracked gold visor reflecting a dim red sun, kneeling on cracked ochre desert
> rock. He slowly reaches a trembling gloved hand toward a single impossible blue flower
> pushing up through the dust; grit drifts in the low gravity. Vast empty rust-coloured
> plain stretches to a hazy horizon behind him, distant dust devils. Bleak desaturated
> palette with one vivid blue accent, harsh low sunlight, 35mm film grain, melancholic
> and awestruck. Ambient: faint wind and the hiss of suit air. SFX: soft servo whir as
> his hand moves. No dialogue, no music.

**Levers:** photorealistic (could go painterly) · 16:9 (could be 9:16) · silent (could
add a breath or VO) · single push-in (could add a `[00:06-00:10]` insert close-up on the
flower).

**Suggested edit:** `Change the flower from blue to glowing bioluminescent teal. Keep
the camera, subject, location, timing, and audio identical.`

---

## Common mistakes

- Pasting whole menu tables into the prompt — pick a few options, write prose.
- Forgetting audio → the model invents unwanted speech.
- Cramming a multi-scene story into 10 seconds — one beat.
- "no people / no text" phrasing → flip it positive ("a deserted street", "a clear sky").
- "locked tripod" → use "static shot".

---

## The reference menus

| File | Covers |
|---|---|
| [`visual-language.md`](references/visual-language.md) | Shot sizes, angles, camera movements, lenses and optics, composition, motion feel, lighting setups, time of day, colour temperature, palettes and grading, film stock, visual styles, mood, texture |
| [`subject-action-continuity.md`](references/subject-action-continuity.md) | Subject descriptor slots (people, creatures, objects), action verbs and pacing, physics cues, setting layers, continuity and multi-shot sequencing, emotional beats |
| [`audio-and-mechanics.md`](references/audio-and-mechanics.md) | Dialogue, SFX, ambient, music, sync, the silence gotcha — plus Omni Flash mechanics: conversational editing, reference inputs, exclusions, timestamps, constraints |