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James Russo
03b82e6ff8
## What Adds the parametrized-render primitive from [hf#592](https://github.com/heygen-com/hyperframes/issues/592) by introducing a `getVariables()` runtime helper plus a CLI `--variables` / `--variables-file` flag. Compositions declare variables once on the root `<html>` element (the existing `data-composition-variables` attribute, which already drives Studio editing UI), read them at runtime via `window.__hyperframes.getVariables()`, and CLI users override them at render time without touching the composition source. This is **PR 1 of a 4-PR stack**: 1. **PR 1 (this one)** — runtime helper + CLI flag + engine injection (top-level renders). 2. PR 2 — sub-comp per-instance scoping (carry the host's `data-variable-values` into the inlined sub-comp's `getVariables()`). 3. PR 3 — schema validation + lint rules (warn on undeclared variable IDs, optional `--strict-variables`). 4. PR 4 — skill / scaffold distribution (SKILL.md, AGENTS.md scaffolds, openai/plugins mirror). ## Why The existing `data-composition-variables` schema declares variable types and defaults but isn't readable from composition scripts and can't be overridden at render time. To produce N variations of a composition today, an agent has to fork the composition or edit the source HTML before each render. `--variables` collapses that into one render call per variation, matching Editframe's `--data` UX without copying their `getRenderData` framing — `getVariables()` is named for the codebase's existing "variables" terminology and works equally in dev preview and at render time. ## How - **Runtime helper** (`packages/core/src/runtime/getVariables.ts`): reads `data-composition-variables` from `document.documentElement`, extracts `{id: default}` defaults, merges `window.__hfVariables` (override) on top, returns `Partial<T>`. Same code path in dev preview (no override) and at render (with override). Generic parameter for typed editor ergonomics. Exposed both as a named export from `@hyperframes/core` and on `window.__hyperframes.getVariables` for vanilla compositions. - **CLI flag** (`packages/cli/src/commands/render.ts`): `--variables '<json>'` and `--variables-file <path>`. `parseVariablesArg` is split out as a pure function (returns a discriminated `{ ok: true } | { ok: false }` union) so all validation paths are unit-testable; the side-effecting `resolveVariablesArg` wraps it with `errorBox` + `process.exit`. Mutually exclusive with `--variables-file`; fail-fast on conflicts, missing file, unparseable JSON, or non-object payloads (string, number, array, null). - **Engine injection** (`packages/engine/src/services/frameCapture.ts`): added an `evaluateOnNewDocument` step right after the `__name` polyfill that sets `window.__hfVariables` to the parsed JSON before any page script runs. Skipped when payload is empty so we don't add pointless init scripts. Plumbed through `CaptureOptions.variables` and `RenderConfig.variables`. Docker mode forwards the flag to the in-container CLI via `dockerRunArgs`. - **Why a separate `__hfVariables` global** instead of writing into `__hyperframes.getVariables()` directly: the helper is an IIFE that has to be defined before composition scripts execute, but the *override* needs to land before *that*. `evaluateOnNewDocument` is the only reliable hook that runs before the runtime IIFE evaluates. Storing the raw value on `__hfVariables` and merging in the helper keeps both paths order-independent. ## Test plan - [x] Unit tests added/updated - 9 jsdom tests for `getVariables()` covering empty state, declared defaults only, override merge, override-wins, declared-only, invalid JSON, non-array payloads, non-object overrides, typed generic. - 7 tests for `parseVariablesArg` covering all validation paths. - 2 integration tests for `renderLocal` confirming `variables` reach `createRenderJob`. - 3 new `dockerRunArgs` assertions for `--variables` passthrough (set / not-set / empty-object). - All existing tests green: core 611, cli 208, engine 519. - [x] Manual testing performed - `npx tsx packages/cli/src/cli.ts render --help` shows both flags + the two new examples. - [x] Documentation updated - `docs/packages/cli.mdx` — added flags to the table and a "Parametrized renders" section with a worked example. - `docs/concepts/data-attributes.mdx` — added `data-composition-variables` row. ## Backwards compatibility Fully backwards compatible. Compositions without `data-composition-variables` work unchanged; `getVariables()` returns `{}` and the engine skips the injection step. 🤖 Generated with [Claude Code](https://claude.com/claude-code)