## drawElement fast-capture — config + CLI flag (stack 1/6)
Foundation layer for the drawElement fast-capture feature: the config surface and CLI/Docker plumbing that the rest of the stack builds on.
### What this adds
- **`packages/engine/src/config.ts`** — new config fields for fast capture: `useDrawElement` / `enableDrawElementWorkerEncode` (macOS-GPU `drawElementImage` capture + worker-offloaded JPEG encode), resolved from env in `resolveConfig` (env `HF_DE_WORKER_ENCODE`). Wired alongside main's existing `staticFrameDedup` (unified downstream in 4/6).
- **`packages/cli/src/commands/render.ts`** — `--experimental-fast-capture` flag → sets `experimentalFastCapture`; `--debug` passthrough.
- **`packages/cli/src/utils/dockerRunArgs.ts`** — pass the fast-capture env through to the container.
- **`.github/workflows/fast-video-validation.yml`** — CI job validating fast-capture renders.
- `.oxlintrc.json` / `.fallowrc.jsonc` — ignore-pattern housekeeping for the new paths.
### Notes
- Config-only + entrypoint; no capture behavior yet (that's 2/6–4/6).
- Tests: `config.test.ts`, `dockerRunArgs.test.ts` added.
---
**Stack (drawElement fast-capture, rebased onto current `main`, supersedes #1295 + #1444):**
1. **#1916 config + CLI** ← you are here
2. #1917 drawElementImage capture service
3. #1918 3D projection + compositor-effect risk gate
4. #1919 frame-capture core (routing, worker-encode, static-dedup unification)
5. #1920 producer render stages + remote bg-image localizer
6. #1921 lint rule + player media sync
⚠️ Intermediate PRs (1–5) are split by package boundary for review and **do not each compile independently** (cross-file deps); the complete feature is green at the stack tip (#1921) — tsc-clean on engine + producer, 231 tests pass.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Root-cause fix for edits being wiped after refresh: the studio's
inspector edits were patched client-side via regex matching in
sourcePatcher.ts, which silently failed for many compositions ("Unable
to patch" toast). Replaced with a server-side patch-element API endpoint
using linkedom for proper DOM parsing via querySelector.
Also fixes the WYSIWYG render bug where sub-composition CSS was not
applied. The CSS scoping generated descendant selectors when both
attributes coexist on the same host element. Fixed to use compound
selectors for the authored root.
Edit persistence:
- New POST /file-mutations/patch-element endpoint using linkedom
- persistDomEditOperations calls server instead of client regex
- 15 tests covering all patch operation types
Render CSS scoping:
- Compound selector for authored root on host element
- Regression test: wysiwyg-subcomp-css (baseline pending Docker)
- 3 unit tests + 1 integration test
GSAP CDN fallback:
- Preview: error-handler catches gsap 404 and loads from CDN
- Producer: rewrites missing local gsap paths to CDN before compile
Studio resilience:
- Error boundary with recoverable UI
- Lazy mediabunny import prevents crash cascade
- Hash routing listens for hashchange events
- Sub-composition duration reads data-hf-authored-duration fallback
- Save debounce 600ms to requestAnimationFrame
Observability:
- PostHog telemetry for crashes, save failures, tab switches, playback,
toolbar actions, navigation, and render starts
Miguel Ángel