hyperframes: add HTML/CSS/GSAP as a parallel composition runtime

Separates creative grammar (renderer_family) from technical engine
(render_runtime) so HyperFrames can stand alongside Remotion as a
first-class runtime instead of masquerading as a Remotion sub-case.
Locks runtime choice at proposal stage and enforces it end-to-end: the
schemas require it, video_compose routes by it, the reviewer fails
closed on silent swaps, and a parametrized contract test walks every
pipeline manifest to ensure each planning-stage skill explains the
conversation to the user. Adds hyperframes_compose (scaffold/lint/
validate/render/doctor/add_block), a playbook -> CSS style bridge, and
vendored HyperFrames Layer 3 skills from commit d291358, pinned via
PROVENANCE.md for future re-sync. Final_review now records
render_runtime_used and runtime_swap_detected so compose lies are
catchable after the fact.

skills/pipelines/explainer/compose-director.md

@@ -6,6 +6,18 @@ You are the Compositor for a generated explainer video. You have `edit_decisions
 
 This is the last technical stage before the video exists as a playable file. Everything converges here.
 
+## Runtime Routing (MANDATORY first step)
+
+Read `edit_decisions.render_runtime` before anything else. It was locked at proposal and must not be changed silently. The rest of this skill's process steps (Remotion public/ staging, word-level caption burn, etc.) assume `render_runtime="remotion"` — the default for data-driven explainers.
+
+- **`render_runtime="hyperframes"`** — HTML/CSS/GSAP render. Do NOT follow the Remotion-specific steps below. Instead: read `skills/core/hyperframes.md`, `.agents/skills/hyperframes/SKILL.md`, and `.agents/skills/hyperframes-cli/SKILL.md`. Call `video_compose` with the edit_decisions unchanged — it will delegate to `hyperframes_compose`, which materializes a workspace under `projects/<name>/hyperframes/`, runs `lint → validate → render`, and returns the MP4. Both lint AND validate must pass before render; contrast can be deferred during iteration but not for final delivery.
+- **`render_runtime="ffmpeg"`** — simple concat/trim. Call `video_compose` directly; it will NOT auto-upgrade to Remotion when this runtime is explicitly locked.
+- **Runtime unavailable** — surface the blocker per AGENT_GUIDE.md > "Escalate Blockers Explicitly" and get user approval (recorded as a `render_runtime_selection` decision in decision_log) before switching.
+
+`final_review.checks.promise_preservation.render_runtime_used` must equal the runtime that actually ran; `runtime_swap_detected` must be `false` unless an approved decision authorizes the swap.
+
+**Pass `proposal_packet` to `video_compose.execute()`** so in-tool swap detection can actually fire. Without it the `runtime_swap_check` is reported as `skipped` and you have to rely on the reviewer skill's cross-artifact comparison instead.
+
 ## Prerequisites
 
 | Layer | Resource | Purpose |

skills/pipelines/explainer/proposal-director.md

@@ -8,6 +8,28 @@ You are the **Proposal Director** for a generated explainer video. You sit betwe
 
 Think of yourself as a creative agency pitching to a client: you present concepts backed by research, show what it'll cost, explain the tradeoffs, and let the client choose.
 
+## Runtime Selection (required field — `render_runtime`)
+
+Explainer proposals must lock **both** a `renderer_family` (creative grammar) and a `render_runtime` (technical engine). Read `skills/meta/animation-runtime-selector.md` for the decision matrix and `AGENT_GUIDE.md` → "Present Both Composition Runtimes (HARD RULE)" for the governance contract.
+
+**MANDATORY workflow — present both runtimes, don't silently default:**
+
+1. Query `video_compose.get_info()["render_engines"]`. If both `remotion` and `hyperframes` are `True`, proceed to step 2. If only one is available, go to step 4 with just that one.
+2. Present both runtimes to the user with brief-specific analysis. For THIS concept:
+   - **Remotion** — one line on fit (mention the React scene stack components that apply), one line on tradeoff.
+   - **HyperFrames** — one line on fit (mention HTML/GSAP motion, registry blocks, kinetic typography if applicable), one line on tradeoff.
+3. Recommend one with rationale tied to the brief's `delivery_promise`, `visual_approach`, and whether word-level caption burn is required (that one forces Remotion).
+4. Wait for explicit user approval. Do NOT write `render_runtime` into `proposal_packet.production_plan` before approval.
+5. Log a `render_runtime_selection` decision in `decision_log` with BOTH runtimes (plus `ffmpeg` if it was a realistic option) in `options_considered`, the user's pick as `selected`, and the rationale as `reason`. If a runtime was unavailable, record it as rejected with `rejected_because: "runtime not available on this machine"`.
+
+Fit cheat-sheet for recommendation (input for the conversation, not an auto-decision):
+
+- Existing React scene stack (text_card, stat_card, bar_chart, line_chart, pie_chart, kpi_grid, callout, comparison, hero_title, caption overlay, anime_scene) fits → recommend **Remotion**.
+- Kinetic typography, custom HTML motion graphics, registry-block-driven scenes, or website-to-video → recommend **HyperFrames**.
+- Word-level/karaoke captions required → **Remotion only** in Phase 1 (caption parity is deferred).
+
+A `render_runtime_selection` decision with only one option considered when both were available is a CRITICAL reviewer finding.
+
 ## Prerequisites
 
 | Layer | Resource | Purpose |