Edit Operations

Every mutation in the SDK is expressed as an EditOp — a plain data object with a discriminated type field. You can submit ops individually through dispatch(), validate them with can(), or group them into a single undo/persist step with batch().

Every element op requires an explicit target (an HfId string or HfId[] array). There is no selection-implicit mutation — the SDK never reads the current selection to decide what to edit. The typed methods on Composition (such as comp.setText() and comp.setStyle()) are convenience sugar that construct and dispatch these same ops.

dispatch, batch, and can

dispatch

comp.dispatch(op: EditOp, opts?: { origin?: unknown }): void

Applies op immediately. Emits a patch event, persists if an adapter is attached, and records a history entry. The optional origin is forwarded verbatim in the resulting PatchEvent; use it to label the source of the change (e.g. "user", "agent", or your own string constant).

comp.dispatch(
  { type: "setStyle", target: "hf-title", styles: { color: "#FFD60A" } },
  { origin: "agent" },
);

batch

comp.batch(fn: () => void, opts?: { origin?: unknown }): void

Groups all dispatch() calls made inside fn into a single undo step, a single persist write, and a single patch event. Use batch() when several mutations belong together logically.

comp.batch(() => {
  comp.dispatch({ type: "setText", target: "hf-title", value: "Launch Day" });
  comp.dispatch({ type: "setStyle", target: "hf-title", styles: { fontSize: "96px" } });
  comp.dispatch({ type: "setTiming", target: "hf-title", start: 0.5, duration: 3 });
});

can

comp.can(op: EditOp): CanResult

Dry-runs op without mutating the document. Returns { ok: true } when dispatch(op) would succeed, or { ok: false; code: string; message: string; hint?: string } when it would be a no-op or error. Use can() as a feature-detection gate before rendering controls or applying optional operations:

const result = comp.can({
  type: "setGsapTween",
  animationId: "anim-1",
  properties: { ease: "power3.out" },
});

if (result.ok) {
  comp.setGsapTween("anim-1", { ease: "power3.out" });
} else {
  console.warn(result.code, result.message);
}

Stable code values for ok: false:

Code	Meaning
`E_TARGET_NOT_FOUND`	The `target` hf-id does not exist in the document.
`E_NO_ROOT`	The document has no root element (empty HTML).
`E_NO_GSAP_TIMELINE`	Op requires a parsed GSAP timeline; parser engine not yet active.
`E_NO_GSAP_SCRIPT`	Op requires a GSAP `<script>` block; none found in the document.

Several Phase-3b GSAP ops (addGsapTween, setGsapTween, removeGsapTween, addGsapKeyframe, setGsapKeyframe, removeGsapKeyframe, etc.) return { ok: false, code: 'E_NO_GSAP_TIMELINE' } from can() until the parser engine ships. dispatch() still applies those ops structurally even when can() returns false.

See also: Composition for the typed-method wrappers, Types for CanResult and EditOp.

Element edits

These ops target one or more elements by explicit hf-id. target accepts a single HfId string or an HfId[] array; when an array is given the op is applied to each id individually within a single batch.

`type`	Key fields	What it does
`setStyle`	`target`, `styles`	Merges CSS inline styles. `null` values remove that property.
`setText`	`target`, `value`	Replaces the element’s direct text content.
`setAttribute`	`target`, `name`, `value`	Sets or removes an HTML attribute. `null` removes it. Does not touch `style`, `class`, or `data-hf-*`.
`setTiming`	`target`, `start?`, `duration?`, `trackIndex?`	Updates one or more timing attributes (`data-start`, `data-duration`, `data-track`). Omitted fields are unchanged.
`setHold`	`target`, `hold`	Sets an elastic hold window; see `ElasticHold` shape below.
`moveElement`	`target`, `x`, `y`	Repositions the element by setting `data-x` / `data-y` (not CSS `left`/`top`).
`removeElement`	`target`	Removes the element and all its children from the document. Inverse of `addElement`.

setStyle

comp.dispatch({
  type: "setStyle",
  target: "hf-card",
  styles: {
    borderRadius: "24px",
    backgroundColor: "#1A1A1A",
    color: null,          // removes the color property
  },
});

styles keys are camelCase property names, matching CSSStyleDeclaration convention.

setText

comp.dispatch({
  type: "setText",
  target: ["hf-headline", "hf-sub"],
  value: "Coming soon",
});

setAttribute

comp.dispatch({
  type: "setAttribute",
  target: "hf-logo",
  name: "src",
  value: "/assets/logo-v2.png",
});

// Remove an attribute:
comp.dispatch({
  type: "setAttribute",
  target: "hf-video",
  name: "autoplay",
  value: null,
});

setTiming

comp.dispatch({
  type: "setTiming",
  target: "hf-title",
  start: 1.5,
  duration: 3,
  trackIndex: 0,
});

setHold

hold is an ElasticHold object:

comp.dispatch({
  type: "setHold",
  target: "hf-badge",
  hold: {
    start: 2,
    end: 5,
    fill: "freeze",   // "freeze" | "loop"
  },
});

moveElement

Sets the element’s position via data-x / data-y attributes. Coordinates are in composition-space pixels.

comp.dispatch({
  type: "moveElement",
  target: "hf-logo",
  x: 120,
  y: 48,
});

Structure

These ops mutate document structure (add/remove/reorder elements, apply class-level styles, or change composition metadata). They do not take a target field in the same form as element edits.

`type`	Key fields	What it does
`addElement`	`parent`, `index`, `html`	Inserts an HTML fragment. Returns the minted hf-id via the typed `comp.addElement()` method.
`reorderElements`	`entries`	Sets inline `z-index` on one or more elements to reorder their stacking.
`setClassStyle`	`selector`, `styles`	Merges CSS rule styles for a class selector. `null` values remove properties.
`deleteAllForSelector`	`selector`	Removes all elements matching the CSS selector from the document.
`setCompositionMetadata`	`width?`, `height?`, `duration?`	Updates top-level composition dimensions and/or total duration.

addElement

parent is the hf-id of the parent element, or null to insert at the document body root. index is the zero-based sibling index (append if >= childCount). html must be a single-root HTML fragment and must not contain <script>.

comp.dispatch({
  type: "addElement",
  parent: "hf-scene-1",
  index: 2,
  html: '<div class="clip" data-start="3" data-duration="2">New layer</div>',
});

Use the typed comp.addElement(parent, index, html) method to get back the minted hf-id.

reorderElements

Each entry sets z-index on one element. Elements must be non-statically positioned for z-index to take effect — the caller must ensure position is set.

comp.dispatch({
  type: "reorderElements",
  entries: [
    { target: "hf-bg",   zIndex: 0 },
    { target: "hf-logo", zIndex: 10 },
    { target: "hf-text", zIndex: 20 },
  ],
});

setClassStyle

comp.dispatch({
  type: "setClassStyle",
  selector: ".caption",
  styles: { fontSize: "14px", fontWeight: "600" },
});

deleteAllForSelector

comp.dispatch({
  type: "deleteAllForSelector",
  selector: ".debug-overlay",
});

setCompositionMetadata

comp.dispatch({
  type: "setCompositionMetadata",
  width: 1920,
  height: 1080,
  duration: 30,
});

Variables

`type`	Key fields	What it does
`setVariableValue`	`id`, `value`	Sets a composition variable’s current value by id. Value may be a string, number, boolean, `FontValue`, or `ImageValue`. Refuses to create an undeclared variable.
`declareVariable`	`decl`	Creates a new variable declaration, or fully replaces an existing one (type, label, default, and all other schema fields — not just the value). The only op that creates the schema entry from scratch.
`removeVariable`	`id`	Removes a variable’s declaration entirely. Live `var.{id}` overrides and `data-var-*` DOM references are left untouched.

// Scalar variable
comp.dispatch({
  type: "setVariableValue",
  id: "brandColor",
  value: "#6C5CE7",
});

// Font variable (object-valued — never a CSS string)
comp.dispatch({
  type: "setVariableValue",
  id: "brand-font",
  value: {
    name: "Inter",
    source: "https://fonts.googleapis.com/css2?family=Inter:wght@400;700",
  },
});

// Image variable (object-valued)
comp.dispatch({
  type: "setVariableValue",
  id: "hero-image",
  value: {
    url: "/assets/hero.jpg",
    alt: "Product hero",
    fit: "cover",
  },
});

// Create a new variable declaration
comp.dispatch({
  type: "declareVariable",
  decl: {
    id: "brandColor",
    type: "color",
    label: "Brand color",
    default: "#6C5CE7",
  },
});

// Remove a variable's declaration
comp.dispatch({ type: "removeVariable", id: "brandColor" });

GSAP tweens

These ops add, edit, and remove GSAP tween entries in the composition’s GSAP script block. They operate by animationId — a stable string identifier minted when a tween is created. Use comp.addGsapTween() or addWithKeyframes to mint a new id; the typed wrapper returns it directly.

Several GSAP ops require the parser engine to be active. Until it ships, can() returns { ok: false, code: 'E_NO_GSAP_TIMELINE' } for these ops. dispatch() still applies the op structurally.

`type`	Key fields	What it does
`addGsapTween`	`target`, `tween`	Adds a new tween for a target hf-id. Returns the minted `animationId` via the typed method.
`setGsapTween`	`animationId`, `properties`	Partially updates an existing tween’s `GsapTweenSpec` fields.
`removeGsapTween`	`animationId`	Removes the tween entirely.
`removeGsapProperty`	`animationId`, `property`, `from?`	Removes one animated property from a tween. `from: true` removes from `fromProperties`; otherwise removes from `toProperties` / `properties`.

addGsapTween

tween is a GsapTweenSpec object:

comp.dispatch({
  type: "addGsapTween",
  target: "hf-title",
  tween: {
    method: "from",
    position: 0,
    duration: 0.8,
    ease: "power3.out",
    fromProperties: { opacity: 0, y: 40 },
  },
});

GsapTweenSpec fields:

Field	Type	Description
`method`	`"from" \| "to" \| "fromTo" \| "set"`	GSAP tween method.
`position`	`number \| string`	Timeline position. Accepts numbers (seconds) or label-relative strings (`"intro+=0.5"`).
`duration`	`number`	Tween duration in seconds.
`ease`	`string`	GSAP ease string (e.g. `"power3.out"`).
`fromProperties`	`Record<string, unknown>`	Start-state properties (used by `from` and `fromTo`).
`toProperties`	`Record<string, unknown>`	End-state properties (used by `fromTo`).
`properties`	`Record<string, unknown>`	Animated properties for `to` tweens.
`repeat`	`number`	Repeat count (`-1` = infinite).
`yoyo`	`boolean`	Reverse on alternating repeats.
`stagger`	`number \| Record<string, unknown>`	Stagger config for multi-target tweens.

setGsapTween

Only the fields you supply are changed; omit any field to leave it unchanged.

comp.dispatch({
  type: "setGsapTween",
  animationId: "anim-1",
  properties: { ease: "elastic.out(1, 0.3)", duration: 1.2 },
});

removeGsapProperty

// Remove 'scale' from the to-properties of an existing tween
comp.dispatch({
  type: "removeGsapProperty",
  animationId: "anim-1",
  property: "scale",
});

// Remove 'opacity' from the from-properties
comp.dispatch({
  type: "removeGsapProperty",
  animationId: "anim-2",
  property: "opacity",
  from: true,
});

Keyframes

Keyframe ops work with tweens that use CSS @keyframes-style percentage arrays rather than a single fromProperties/toProperties shape.

`type`	Key fields	What it does
`setGsapKeyframe`	`animationId`, `keyframeIndex`, `position?`, `value?`, `ease?`	Updates one keyframe by index inside an existing keyframed tween.
`addGsapKeyframe`	`animationId`, `position`, `value`	Appends a new keyframe at a given percentage position.
`removeGsapKeyframe`	`animationId`, `percentage`	Removes the keyframe at a specific percentage.
`removeAllKeyframes`	`animationId`	Clears all keyframes from a tween, leaving the tween shell intact.
`convertToKeyframes`	`animationId`, `resolvedFromValues?`	Converts a `from`/`to`/`fromTo` tween into keyframe form. `resolvedFromValues` provides live computed values for the 0% stop.
`materializeKeyframes`	`animationId`, `keyframes`, `easeEach?`, `resolvedSelector?`	Writes a complete keyframe set to an existing tween, replacing any previous keyframes.
`addWithKeyframes`	`targetSelector`, `position`, `duration`, `keyframes`, `ease?`	Creates a new keyframed tween for the given CSS selector. Returns minted `animationId` via typed method.
`replaceWithKeyframes`	`animationId`, `targetSelector`, `position`, `duration`, `keyframes`, `ease?`	Atomically removes an existing tween and inserts a new keyframed tween.
`splitIntoPropertyGroups`	`animationId`	Splits a multi-property keyframed tween into one tween per animated property.
`splitAnimations`	`originalId`, `newId`, `splitTime`, `elementStart`, `elementDuration`	Splits one tween into two at `splitTime`. The second half gets `newId`.
`unrollDynamicAnimations`	`animationId`, `elements`	Converts a selector-targeted tween that matches multiple elements into per-element keyframe tweens.

materializeKeyframes

keyframes is an array of { percentage, properties, ease? } objects:

comp.dispatch({
  type: "materializeKeyframes",
  animationId: "anim-3",
  keyframes: [
    { percentage: 0,   properties: { opacity: 0, y: 30 } },
    { percentage: 100, properties: { opacity: 1, y: 0 }, ease: "power2.out" },
  ],
  easeEach: "none",
  resolvedSelector: "#hf-title",
});

addWithKeyframes / replaceWithKeyframes

position is a number (seconds) — unlike GsapTweenSpec.position, label-relative strings are not accepted here.

// Create a new keyframed tween:
comp.dispatch({
  type: "addWithKeyframes",
  targetSelector: "#hf-card",
  position: 1.5,
  duration: 0.6,
  keyframes: [
    { percentage: 0,   properties: { scale: 0.8, opacity: 0 } },
    { percentage: 100, properties: { scale: 1,   opacity: 1 } },
  ],
  ease: "back.out(1.7)",
});

// Replace an existing tween atomically:
comp.dispatch({
  type: "replaceWithKeyframes",
  animationId: "anim-4",
  targetSelector: "#hf-card",
  position: 1.5,
  duration: 0.6,
  keyframes: [
    { percentage: 0,   properties: { scale: 0.9 } },
    { percentage: 100, properties: { scale: 1 } },
  ],
});

After replaceWithKeyframes, position-derived tween IDs renumber. Re-query comp.getElement(id).animationIds to discover the new ID rather than assuming it matches the old one.

KeyframeSpec fields:

Field	Type	Description
`percentage`	`number`	Keyframe stop position (0–100).
`properties`	`Record<string, number \| string>`	CSS / GSAP properties at this stop.
`ease`	`string`	Ease applied from this stop to the next.
`auto`	`boolean`	GSAP endpoint flag — emitted as numeric `_auto: 1`.

Labels

GSAP timeline labels mark named positions (in seconds) in the master timeline. Labels are referenced in GsapTweenSpec.position as strings like "intro" or "intro+=0.5".

`type`	Key fields	What it does
`addLabel`	`name`, `position`	Adds a named label at a timeline position (seconds).
`removeLabel`	`name`	Removes a named label.

comp.dispatch({ type: "addLabel", name: "intro", position: 0 });
comp.dispatch({ type: "addLabel", name: "outro", position: 8 });

// Tween positioned relative to a label:
comp.dispatch({
  type: "addGsapTween",
  target: "hf-cta",
  tween: {
    method: "from",
    position: "outro-=0.5",
    duration: 0.4,
    fromProperties: { opacity: 0 },
  },
});

comp.dispatch({ type: "removeLabel", name: "intro" });

Arc paths

Arc path ops control the motion path of a GSAP tween — the curve along which an element travels.

`type`	Key fields	What it does
`setArcPath`	`animationId`, `config`	Creates or replaces the arc-path config on a tween.
`updateArcSegment`	`animationId`, `segmentIndex`, `update`	Updates one segment’s curviness or control points.
`removeArcPath`	`animationId`	Removes the arc-path from a tween, reverting to a straight-line path.

setArcPath

config shape:

comp.dispatch({
  type: "setArcPath",
  animationId: "anim-5",
  config: {
    enabled: true,
    autoRotate: true,            // boolean, or a number (degrees offset)
    segments: [
      {
        curviness: 1.5,
        cp1: { x: 200, y: -80 }, // first control point
        cp2: { x: 400, y: 20 },  // second control point
      },
    ],
  },
});

Field	Type	Description
`enabled`	`boolean`	Whether the arc path is active.
`autoRotate`	`boolean \| number`	`true` = auto-rotate to follow path tangent; a number offsets the rotation by that many degrees.
`segments`	`Array<{ curviness?, cp1?, cp2? }>`	Per-segment path definition. `curviness` is a GSAP Bezier curviness value; `cp1`/`cp2` are control-point coordinates in composition space.

updateArcSegment

comp.dispatch({
  type: "updateArcSegment",
  animationId: "anim-5",
  segmentIndex: 0,
  update: { curviness: 2, cp1: { x: 220, y: -100 } },
});

Overview

Guides

Reference

dispatch, batch, and can

dispatch

batch

can

Element edits

setStyle

setText

setAttribute

setTiming

setHold

moveElement

Structure

addElement

reorderElements

setClassStyle

deleteAllForSelector

setCompositionMetadata

Variables

GSAP tweens

addGsapTween

setGsapTween

removeGsapProperty

Keyframes

materializeKeyframes

addWithKeyframes / replaceWithKeyframes

Labels

Arc paths

setArcPath

updateArcSegment

​dispatch, batch, and can

​dispatch

​batch

​can

​Element edits

​setStyle

​setText

​setAttribute

​setTiming

​setHold

​moveElement

​Structure

​addElement

​reorderElements

​setClassStyle

​deleteAllForSelector

​setCompositionMetadata

​Variables

​GSAP tweens

​addGsapTween

​setGsapTween

​removeGsapProperty

​Keyframes

​materializeKeyframes

​addWithKeyframes / replaceWithKeyframes

​Labels

​Arc paths

​setArcPath

​updateArcSegment

dispatch, batch, and can

dispatch

batch

can

Element edits

setStyle

setText

setAttribute

setTiming

setHold

moveElement

Structure

addElement

reorderElements

setClassStyle

deleteAllForSelector

setCompositionMetadata

Variables

GSAP tweens

addGsapTween

setGsapTween

removeGsapProperty

Keyframes

materializeKeyframes

addWithKeyframes / replaceWithKeyframes

Labels

Arc paths

setArcPath

updateArcSegment