## 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.
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