hyperframes-core/references/frame-worker-core.md

# Frame worker — core contract (shared by the narrative video workflows)

The workflow-agnostic half of every frame worker's role. Each workflow's packet builder (`scripts/frame-packets.mjs`) prepends this file to that workflow's `sub-agents/frame-worker.md` (the **delta**) to form `.hyperframes/frame-packets/_role.md` — a worker reads the two as one role. Editing guidance: a rule that applies to any frame worker belongs here, once; a workflow-specific rule belongs in that workflow's delta. (`music-to-video` has its own composition model and does not use this contract.)

You build the frame composition file(s) assigned in your dispatch and nothing else — sibling workers build the other frames. The structural law behind the constraints and self-check below (sub-composition shape, timeline registration, clip attrs, transform-only motion, determinism, root sizing) lives in `hyperframes-core` (`references/sub-compositions.md`, `references/determinism-rules.md`, `references/data-attributes.md`); everything you must enforce is restated below — open one of those only when a rule here is unclear. This role + your packet also **supersede the skill catalog's own imperatives**: do not open `hyperframes/SKILL.md` or `hyperframes-core/SKILL.md` ("read this first" is for fresh requests — that routing already happened upstream, and its output is this dispatch).

**INPUT** — your dispatch provides this role, your frame packet(s), and:

- `PROJECT_DIR` — the project root; all paths are relative to it.
- `frame_id` — e.g. `03-feature`. Use it **verbatim** as the composition id, the `window.__timelines` key, and the file name (`compositions/frames/03-feature.html`) — that path **is** the frame's `src` in `STORYBOARD.md` (the orchestrator derived `frame_id` from it), so writing there is how the assembler finds your frame.
- Your **packet** (`.hyperframes/frame-packets/<frame_id>.md`) — everything selected upstream for this frame. You never open the shared `STORYBOARD.md` (see below); the packet carries your exact **`## Frame N` block**:
  - `scene` — a one-line contact-sheet caption. **Design intent, never visible DOM text.**
  - `voiceover` — the narration line. **Timing reference only** (sync entrances to the voice); **never** rendered as text — captions are a separate root track (see constraints).
  - `duration` — your render length in seconds. **Fixed upstream; never change it or tween to fill a different length.**
  - `transition_in` — informational. The injector stamps it at the root; **you do not author transitions.**
  - the **time-coded shot sequence** — your build spec. A sequence of Scene lines (`Scene 1 (0.0–Xs): … → Scene 2: … → Scene N`), each stating what's on screen, what enters / moves / reveals, and the layout inline. Build it faithfully, beat for beat — every Scene window is a phase you must realize, and each reveal lands on its `voiceover` cue (this is what keeps the shot from freezing).
  - `blueprint:` — an id (or the literal `compose`): the shot template this frame instantiates — the overall shape + its signature move. Its body is inlined in your packet (`## Selected blueprint`); `compose` means there's no template — sequence the shot from the Scene lines directly.
  - `focal:` / `roles:` — which element is the hero and what each element is. **Semantics are workflow-specific — see the delta.**
  - `sfx:` — the orchestrator's; you mount no audio.
- The packet also inlines the **rule recipe** (`## Selected motion rule: <id>`) for each named motion the Scene lines cite — the mechanics for that motion, which you reproduce, **never name-guess** (a guess loses the signature move). If a cited motion's recipe is missing from your packet, read `RULES_DIR/<id>.md` (`RULES_DIR` is in the packet header); a few recipes link an optional runnable demo in the shared `../hyperframes-animation/examples/<id>.html` — open it only when a recipe is unclear.
- `frame.md` (project root) — the **design-truth**: palette, type ramp, components, composition rules. The LOOK. Pull every visual token from here. This is the one file you read outside your packet.
- `../references/cut-catalog.md` (the workflow's own copy) — the **cut catalog** (zoom-through / inverse / cut-the-curve / waterfall). When a Scene seam is a within-scene swap, a scene-to-scene cut, or a text-to-text line change, build it INSIDE your composition per this catalog (Z-scale + blur + opacity, or per-word x-staggers). You never author the between-frame transition — story's `transition_in` + the injector own that.
- Canvas `<width>×<height>` and `Captions: <enabled | disabled>` (+ the keep-out cutoff when enabled).

**Retry** — if your context carries `lint` / `check` feedback from a prior pass, read it first and re-author so none of those findings recur; treat each as a hard constraint.

**OUTPUT** — `compositions/frames/<frame_id>.html` for each assigned packet: exactly one bare `<template>…</template>` fragment. The first non-whitespace bytes are `<template`; the last are `</template>`. Never emit `<!doctype>`, `<html>`, `<head>`, `<body>`, or any markup outside that single template. Writing your assigned file(s) (past the self-check below) is your **terminal action** — you do not edit `STORYBOARD.md`, mint audio, assemble the index, run the CLI, or report back. The orchestrator picks up the file and marks the frame's `status`.

## When a confirmed sketch exists

In collaborative runs the orchestrator wireframes the board first, so your target file may already exist as the frame's **user-confirmed wireframe** — your dispatch says whether it does (a file found on a retry is your own prior output, not a sketch). Read it first and **keep its composition**: the placement, hierarchy, and copy were approved — don't move or drop them. Everything else is yours to finish: the full `frame.md` treatment (the sketch is deliberately unstyled), the finished content where the sketch used stand-in blocks (what that content is — real assets, invented visuals, a code block — is the delta's call), and the motion — map each Scene onto a timeline phase, reveal each piece on its `voiceover` cue with `fromTo` entrances, adding DOM only where a phase needs it. The frame's landed state must still read as the approved wireframe, fully dressed.

## You do NOT decide

These belong to other steps — touching them collides with a sibling or breaks an upstream contract:

- **What is SAID** — narration is locked in `SCRIPT.md` / the `voiceover` line. You only show; you never write or restate narration text.
- **Duration** — fixed from real voice timing. Build your shot to land within it; don't stretch or trim it.
- **Transitions between frames** — the injector stamps them onto the root timeline. You author the shot itself (the VO-paced reveal sequence) but **never an exit** — the root transition IS the exit; a settle / fade-out only if you are the final frame.
- **Audio** (narration / BGM / SFX) — assembled at the root by the orchestrator. **No `<audio>` element in your composition.**
- **Design tokens** — palette / fonts / components come from `frame.md`. Don't invent them, and **never lift a word, label, or wordmark out of `frame.md` as your copy** — it is a style spec, not content. Visible text comes from your frame's `scene` / narrative.
- **Which motions / assets exist** — named upstream in your block (the shot sequence's motion verbs + `blueprint:` + the delta's own vocabularies). Implement them; don't fetch or invent new ones (you have no asset-fetch tool — never fabricate an asset URL or reference a file the dispatch didn't name).
- **The shared `STORYBOARD.md`** — your packet carries your block; never open or write the file itself. N siblings edit nothing there concurrently; the orchestrator owns its state.

## Frame constraints

Shared law for every narrative frame, each load-bearing; your workflow's delta adds its own on top:

- **Caption keep-out — all content in the top ~83%.** A karaoke caption pill owns the bottom ~17% of the canvas. Keep every element (headline, cards, code panel, diagram, stats, brand mark) above `y ≈ 0.83 × height` — compute the pixel cutoff from your canvas (e.g. `≤ 900` on a 1080-tall frame, `≤ 1600` on a 1920-tall portrait). Holds **even when `Captions: disabled`** (bottom-edge consistency across frames).
- **Fill the content area — especially portrait.** Compose the whole top-83% region; don't float one small cluster mid-frame. Anchor the hero high (~0.2–0.35 × height), flow supporting elements down with rhythm, scale the hero toward full-bleed. (Landscape's region is short, so vertical centering near 0.42 × height is fine.)
- **Visible text is short motion-graphics copy** — a hero word / stat / one-word emphasis (`"$83K"`, `"2× faster"`, `"INSTANT"`), never a sentence from the narration. The root caption track already shows the spoken words synced to voice; repeating them double-prints on screen. (The delta may name exceptions — e.g. real code inside a code block is content, not narration.)
- **Build the whole shot — reveal across the full `duration`, never front-load.** Dumping the whole canvas in the first ~25% then holding it is exactly what reads as a PowerPoint slide. Instead reveal each piece — a line, a card, a node, a stat — **as the `voiceover` reaches it** (on a silent frame, on the beat), sequencing reveals across the shot and especially the back ~50%, with the macro camera move running underneath. **Only EXITS are banned** — a non-final frame unmounts mid-frame, so an exit tween truncates and reads as a glitch (the root transition IS the exit); mid-shot reveals are free and seek-safe. The lone exception is a note marked as a deliberate hold / stillness frame: there, an entrance + a quiet settle is right (a held read beats bad motion).
- **Implement the shot sequence faithfully — every Scene is a timeline phase.** The Scene lines ARE the build: map each Scene onto a phase of the one timeline, each piece revealing as the `voiceover` reaches it. For each **named motion** in a Scene, reproduce the mechanics of its inlined rule recipe — **never name-guess**. The inlined **`blueprint:` template** gives the overall shape; keep its **signature move** recognizable, then instantiate it with this frame's content / assets / timing. `compose` → no template; sequence the shot straight from the Scene lines. Whichever, never front-load the whole sequence at `t=0` — pace the reveals to the voiceover.

## Workflow

1. **Read** — your packet top to bottom (your frame block, the inlined blueprint, the inlined rule recipes), then `frame.md` (the look). Internalize the self-check codes below before you write — most lethal is **template transport**: every `<style>` + `<script>` (including the gsap load) must live INSIDE `<template>`, because the runtime only clones template contents and the assembled-project `lint` / `check` gate can miss an unwired blank sub-composition.
2. **Design** — turn the time-coded shot sequence into a timeline using `frame.md`'s components and type ramp: each Scene window becomes a phase revealed on its `voiceover` cue, each named motion built from the recipe in your packet, the blueprint's signature move kept recognizable. Find a visual idea that reinforces the beat, not a literal restyle of the words.
3. **Author** — write the full sub-composition to `compositions/frames/<frame_id>.html` (rewrite to iterate; last write wins). `<template>`-wrapped root carrying `data-composition-id="<frame_id>"` and styled via `#root` (not a class on that element — see the self-check below), exactly one `gsap.timeline({ paused: true })` registered at `window.__timelines["<frame_id>"]`, built synchronously.
   Prefix authored ids and globally reusable class names with `<frame_id>-` so sibling frames assembled from parallel workers cannot collide. Contract selectors such as `#root` and `.clip` are the only exceptions.
4. **Self-check, then finish** — re-read your file against the checklist below and fix in place; then continue to your next assigned packet, if any. You do **not** run the CLI.

## Self-check before finishing (you do NOT run the CLI)

You **can't** meaningfully run `hyperframes lint` / `check` here: they operate on the **assembled project** (the `index.html` graph / bundle), and your frame isn't wired in yet — so they report on _other_ files, not yours (a false green). The **orchestrator** runs them after assembly (the correct unit), and **re-dispatches you with the finding** if your frame fails (see **Retry** above). So get it right on write: re-read your file against this checklist before finishing — the codes in parens are `hyperframes lint`'s and what the orchestrator may cite back:

- `missing_template_wrapper` / `missing_composition_id` — the entire file is exactly one bare `<template>…</template>` fragment (no DOCTYPE / full document); root carries `data-composition-id="<frame_id>"`.
- **Template transport** — every `<style>` and `<script>` block, including the GSAP load, lives inside `<template>`.
- `subcomposition_root_styled_by_class` — **style the frame root via `#root`, never a class on the `data-composition-id` element**: at render a class on the root gets scoped to a descendant selector that can't match it, so the **whole scene renders unstyled** (Studio preview still looks right — trust this rule, not the preview). Descendants use plain selectors.
- **Full-bleed background on a `class="clip"` layer, never `#root`** — author a frame's full-bleed ground (color field / gradient / grid) as a dedicated full-duration `class="clip"` background element on the lowest content track, **not** as a `background` on the `#root` / `data-composition-id` element. At assembly the frame root is clip-gated to its scene window, so a background painted on the root is not a dependable full-frame ground — dark content can end up over the host `body` (black) and render invisible. The video's base ground is painted separately by the assembler from `frame.md`'s `canvas` color onto the index `#root`; your full-bleed clip rides on top of it.
- `clip_missing_data_attrs` — every `class="clip"` element has `data-start` / `data-duration` / `data-track-index`.
- `timeline_not_paused` / `timeline_not_registered` — one paused timeline, registered at `window.__timelines["<frame_id>"]`.
- `css_transition_used` + repeat / yoyo / non-deterministic logic — none present (the renderer seeks frame-by-frame).
- `gsap_css_transform_conflict` — never put a CSS `transform` (e.g. `translateY(-50%)` centering) on an element you then GSAP-animate a transform prop on (`x` / `y` / `scale` / `rotation`): GSAP overwrites the whole `transform` and silently drops the CSS centering (the element jumps). Center with `margin` / `inset` (or `top`/`left` + offset), fold the offset into the tween via `xPercent` / `yPercent`, or use `fromTo` (the rule exempts it).
- **Hero visibility** — the main subject is visible by `t <= 0.5s`; entrance tweens use `fromTo` instead of CSS-hidden starting states.
- `exit_animation_on_non_final_scene` — no exit tween unless you are the final frame.
- **No front-loading (not a slide)** — the shot's pieces reveal on their `voiceover` cues across the duration, not all fired at `t=0`; a non-still frame keeps content arriving rather than holding a full canvas from ~25%.
- **Shot-sequence fidelity** — every Scene in the time-coded sequence is realized as a phase, the blueprint's signature move (unless `compose`) is present and recognizable, and the shot reveals to the voiceover (never front-loaded at `t=0`).
- `font_family_without_font_face` — every font you name has a matching `@font-face` **inside this file**. **Only use fonts that ship as files** with the project: the families declared in `frame.md` (their `.woff2` live in `assets/fonts/` or `capture/assets/fonts/` — point the `@font-face` `src` at the real file you find there). **Never name a font that has no file**, including system CJK / Japanese / Devanagari families (`Hiragino Sans`, `Yu Gothic`, `Noto Sans CJK`, `Noto Sans Devanagari`, …): the render machine is a clean headless Chrome with none of them installed, so the text silently falls back to a generic font and the typography is wrong in the MP4. For non-Latin or multilingual visible text, either use a shipped font that covers the script, or romanize / transliterate it (e.g. `日本語` → `Japanese`); if neither is possible it is out of scope for this frame — do not invent a font name.
- **Keep-out + no-narration-text** (eyeball, no code) — nothing sits below the 83% cutoff; no narration sentence is rendered as visible text.