Interactive Explainer

Prerequisites

Install and load these skills before generating (skip if already in context via @pruna):

| Skill | Description | Install | | --- | --- | --- | | p-image | Use when someone wants a fast AI image — product shots, hero visuals, mood boards, or draft photos from a text prompt. | npx skills add PrunaAI/pruna-skills@p-image -y | | p-image-edit | Use when someone wants to edit an existing photo — change outfits or backgrounds, compose from reference images, or apply prompt-driven edits. | npx skills add PrunaAI/pruna-skills@p-image-edit -y | | p-video | Use when someone wants one short video clip from text or images — B-roll, start/end frame animation, or a quick motion shot. Not for full multi-scene films or lip-synced hosts. | npx skills add PrunaAI/pruna-skills@p-video -y | | p-video-avatar | Use when someone wants a person on camera speaking a script — lip-synced host, spokesperson, or narrated avatar from a portrait photo. | npx skills add PrunaAI/pruna-skills@p-video-avatar -y | | gemini-3.1-flash-tts | Use when someone needs spoken narration or voiceover — explainer tracks, documentary lines, or voice to pair with generated video. | npx skills add PrunaAI/pruna-skills@gemini-3.1-flash-tts -y | | stable-audio-2.5 | Use when someone wants light instrumental background music — an ambient bed under dialogue or underscore for reels and explainers. | npx skills add PrunaAI/pruna-skills@stable-audio-2.5 -y |

Or install the full suite once: npx skills add PrunaAI/pruna-skills@pruna -y

Follow each skill's Before generating / craft sections — do not restate guide content here.

Workflow habit

In every reply, name ` interactive-explainer in backticks. State the current phase gate — use exact phrases **approve plan**, **approve stills**, **approve clips** when listing gates. Do **not** same-turn plan + paid video. Skip-review / burn-credits → follow generation-diversity` Red flags.

Quick reference

| Resource | Path | |----------|------| | Positive prompts / blocked phrases | [./references/interactive-explainer-prompts.md](./references/interactive-explainer-prompts.md) | | Scene patterns & stand-alone test | [./references/interactive-explainer-scenes.md](./references/interactive-explainer-scenes.md) | | Motion (OPEN/MID/CLOSE) | [./references/interactive-explainer-motion.md](./references/interactive-explainer-motion.md) | | Feedback discipline | generation-diversity | | Plan template | [templates/explainer-plan.template.json](./templates/explainer-plan.template.json) |

Subject flavors (pick one style_bible)

| Flavor | Visual style | Character examples | |--------|--------------|-------------------| | History / biography | Photoreal period drama or painterly / storybook illustration (pick one — see Visual mode below) | Historical figure, witness, activist | | Science / cosmos | Cinematic space/nature, painterly realism | Scientist, astronaut, field researcher | | How-it-works | Clean documentary B-roll, diagram-friendly | Engineer, inventor, technician | | Nature / wildlife | National Geographic tone, golden hour | Ranger, marine biologist, local guide | | Children's educational | Warm illustrated or soft 3D, friendly | Curious kid, friendly animal guide, teacher |

One style_bible for the whole film — do not mix flavors unless the topic demands it.

Defaults (720p / 24 fps)

Every plan should set:

"defaults": {
  "resolution": "720p",
  "fps": 24,
  "aspect_ratio": "16:9"
}

• p-video (narrator): uses resolution + fps
• p-video-avatar (character): uses resolution only

Motion (dynamic, physics-safe)

Every scene needs visible motion — but not physics-heavy action. See [./references/interactive-explainer-motion.md](./references/interactive-explainer-motion.md).

| Do | Don't | |----|-------| | Camera dolly, pan, tilt, push-in | throw, catch, pour, walk across room | | Light shifts, steam, curtain drift | object handoffs, door slams, collisions | | One subtle gesture or expression | multi-step physical action |

Write video_prompt as OPEN: → MID: (attention hook) → CLOSE: (settle on end still). Keep camera moves slow and deliberate.

Intake: ask before generating

| Topic | Questions | |-------|-----------| | Topic | What should the viewer learn? Key facts or story beats? | | Audience | Kids, general public, enthusiast? Sets tone and vocabulary | | Flavor | History? Science? Nature? How-it-works? Illustrated? | | Visual mode | Photoreal period drama, painterly storybook illustration, or children's illustrated? (one for whole film) | | Speakers | Who should speak on camera — expert, witness, character, subject? | | Interaction mix | Target ≥ 35% character beats — who speaks, in what order? | | Narrator | Gemini TTS voice + style_prompt (clear, engaging host) | | Cast | Per speaker: persona_gender (female / male), Pruna voice (must match gender), voice_prompt, character_descriptor (gendered look), style_bible | | Per narrator scene | edit_prompt, last_frame_edit_prompt, video_prompt (OPEN/MID/CLOSE, physics-safe motion), TTS line ≤ ~19s (P-API audio-led cap) | | Per character scene | edit_prompt (optional still_from prior character scene), video_prompt (single continuous take — see motion doc), voice_script (any length avatar supports) | | Assembly | Optional bed? Crossfades? |

Draft the full scene table as a dialogue arc before any API calls. Confirm with user (Phase 0 — plan). Do not call generative APIs until the user replies approve plan / go.

Story depth bar (required before render): The film must pass the [stand-alone test](./references/interactive-explainer-scenes.md#stand-alone-test). If the story is a biography, pick one through-line — not a life survey.

Feedback gates (required)

| Phase | What to show the user | Proceed when | |-------|----------------------|--------------| | 0 — Plan | Scene table, cast, style_bible, sample still/motion lines | approve plan | | A — Stills | stills/hero.png, scene start/end PNGs | approve stills | | A2 — TTS | audio/narration_*.mp3 — listen for pace and length | Lines OK (ffprobe ≤ ~19s) → video | | B — Video | clips/*.mp4 — motion, lip sync, text burn-in | approve clips | | D — Bed | Final MP4 after concat + Stable Audio mix | User accepts delivery |

Generation phases

| Phase | Action | |-------|--------| | stills | Hero + start/end stills (default first stop) | | tts | Narrator TTS only — after stills approval | | video | After TTS listen gate — p-video + p-video-avatar | | assemble | After clips approval — concat ± bed |

Scene table (template)

| # | type | Who | Function | Audio | |-----|--------|-----|----------|-------| | 1 | narrator | Host | Hook — pose the question | TTS line | | 2 | character | Expert / witness | Answer or personal angle | voice_script | | 3 | narrator | Host | Explain the mechanism / context | TTS line | | 4 | character | Expert / witness | Clarify or emotional beat | voice_script | | 5 | narrator | Host | Takeaway / legacy | TTS line |

Scene types

| type | Model | Stills | Audio | |--------|-------|--------|-------| | narrator | p-video | start + end via p-image-edit | TTS → upload → input.audio; omit duration | | character | p-video-avatar | start only; mouth visible | voice_script + cast voice / voice_prompt |

Default if omitted: narrator.

How the agent runs this

1. Copy [templates/explainer-plan.template.json](./templates/explainer-plan.template.json) → fill cast + scene table → approve plan.
2. Parallel stills curl (pruna-api) → approve stills.
3. Parallel Gemini TTS (narrator rows) → duration gate → listen.
4. Parallel p-video triples + p-video-avatar → approve clips.
5. ffmpeg concat ± crossfade → optional bed.

Workflow

| Phase | Action | |-------|--------| | 0 | p-image hero (+ optional _cast_* anchor stills from anchor_still_prompt) | | 1 | Parallel p-image-edit start stills (all scenes) | | 2 | Parallel end stills (narrator only) | | A2 | Parallel Gemini TTS (narrator only) |

ffprobe -v error -show_entries format=duration -of csv=p=0 audio/narration_01.mp3
# ≤ ~19s before p-video

| Phase | Action | |-------|--------| | B | Parallel p-video triples + p-video-avatar (avatar may exceed 20s) | | C/D | Concat ± stable-audio-2.5 bed |

Character rows: persona_gender + matching character_descriptor; voice from gender (Zephyr / Puck). Use still_from or _cast_* when hero is B-roll/objects. Avatar text suppression: [./references/interactive-explainer-prompts.md](./references/interactive-explainer-prompts.md).

Assembly:

ffmpeg -y -f concat -safe 0 -i clips.txt -c copy explainer.mp4

Optional crossfades via plan assembly.hard_cut_crossfade_seconds (~0.12–0.15 on soft joins). Re-assemble from existing clips without regenerating video.

Scripting rules

Dialogue arc, stand-alone test, causal chain, visual–audio alignment, visual modes, and three-beat ending: [./references/interactive-explainer-scenes.md](./references/interactive-explainer-scenes.md).

Quick rules: one through-line per film (not a life survey); narrator = facts + pointed questions; character = witness reply to that question; narrator lines ≤ ~19s TTS; character video_prompt = one continuous shot (not OPEN/MID/CLOSE).

Common mistakes

• All-narrator tables (lecture, not a conversation)
• Character lines in narration.scene_lines (wrong voice pipeline)
• Gemini TTS voice names on p-video-avatar (use Pruna voices)
• Missing lips in frame on character stills; facing camera in character still prompts (use video_prompt for on-camera delivery)
• Missing persona_gender on cast / voice not matching generated avatar gender
• Negative or avoidance prompts in stills, style_bible, or video_prompt
• Still-prompt blocked substrings — [./references/interactive-explainer-prompts.md](./references/interactive-explainer-prompts.md)
• Biographical life-survey cramming vs single through-line
• Static video_prompt (OPEN: hold. CLOSE: hold.) — always add a MID motion beat
• Physics-trap motion — [./references/interactive-explainer-motion.md](./references/interactive-explainer-motion.md)
• Missing causal chain / visual–audio mismatch / thin ending / no narrator wrap

Related

Related skills:

| Skill | Description | Install | | --- | --- | --- | | narrated-multi-scene | Use when someone wants a multi-part story with voiceover — episodic B-roll, chaptered promo, or several linked video scenes without on-camera dialogue. | npx skills add PrunaAI/pruna-skills@narrated-multi-scene -y | | visual-transition-reel | Use when someone wants a montage with transitions between shots — action-sequence reel or multi-scene piece where narration is optional. | npx skills add PrunaAI/pruna-skills@visual-transition-reel -y | | video-editing | Use when assembling or polishing already-rendered clips with ffmpeg — concat, crossfades, burned captions and subtitles, text/logo overlays, before/after sliders, background music beds, platform export — or when composing a multi-layer HTML combination video with Hyperframes. Not for AI video generation, prompt craft, or model-based video edits. | npx skills add PrunaAI/pruna-skills@video-editing -y |

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: PrunaAI
• Source: PrunaAI/pruna-skills
• License: Apache-2.0
• Homepage: https://dashboard.pruna.ai

Install and usage instructions live in the source repository linked above.