Add HyperFrames skills

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011h6NB8JQtfPc6eRCefEzBB

.agents/skills/remotion-to-hyperframes/scripts/frame_strip.sh

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+#!/usr/bin/env bash
+# frame_strip.sh — produce a side-by-side comparison strip from two videos.
+#
+# Used to debug failing render_diff.sh runs visually: pick a sample timestamp
+# range, extract frames from both videos, lay them out as a grid for review.
+#
+# Usage:
+#   frame_strip.sh <baseline.mp4> <translated.mp4> [output-dir] [samples]
+#
+# Defaults: output-dir=./strip-out, samples=8 (evenly spaced across duration).
+# Output:
+#   strip.png         — single PNG with `samples` rows, each row is
+#                       (baseline frame | translated frame) at one timestamp
+#   timestamps.txt    — the timestamps sampled
+
+set -euo pipefail
+
+if [[ $# -lt 2 || $# -gt 4 ]]; then
+  echo "usage: $0 <baseline.mp4> <translated.mp4> [output-dir] [samples]" >&2
+  exit 2
+fi
+
+BASELINE="$1"
+TRANSLATED="$2"
+OUTDIR="${3:-./strip-out}"
+SAMPLES="${4:-8}"
+
+if ! command -v ffmpeg >/dev/null 2>&1 || ! command -v ffprobe >/dev/null 2>&1; then
+  echo "error: ffmpeg/ffprobe not on PATH" >&2
+  exit 2
+fi
+
+mkdir -p "$OUTDIR"
+
+# Build the strip in a single ffmpeg invocation. Two inputs (baseline and
+# translated) are sampled at N evenly-spaced timestamps via the `select`
+# filter, then assembled with hstack (per-row pairs) + vstack (rows).
+# Earlier versions spawned 3 ffmpeg calls per timestamp + a final vstack;
+# this is one call regardless of N.
+python3 - "$BASELINE" "$TRANSLATED" "$OUTDIR" "$SAMPLES" <<'PY'
+import json
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+baseline, translated, outdir, samples = sys.argv[1], sys.argv[2], Path(sys.argv[3]), int(sys.argv[4])
+
+# Read fps + duration from the baseline so we can map timestamps to frame
+# indexes for the `select` filter (frame-accurate, doesn't depend on
+# keyframe alignment).
+probe = subprocess.run(
+    ["ffprobe", "-v", "error", "-select_streams", "v:0",
+     "-show_entries", "stream=r_frame_rate,nb_read_frames,duration",
+     "-show_entries", "format=duration",
+     "-of", "json", "-count_frames", "--", baseline],
+    check=True, capture_output=True, text=True,
+)
+data = json.loads(probe.stdout)
+stream = data["streams"][0]
+num, den = stream["r_frame_rate"].split("/")
+fps = float(num) / float(den)
+nb_frames = int(stream.get("nb_read_frames") or 0)
+if nb_frames <= 0:
+    duration = float(stream.get("duration") or data["format"]["duration"])
+    nb_frames = int(duration * fps)
+
+# Even-spaced sample frames in the 5%-95% window (skip fade-in/out noise).
+start = max(0, int(nb_frames * 0.05))
+end = max(start, int(nb_frames * 0.95) - 1)
+if samples == 1:
+    frames = [start]
+else:
+    step = (end - start) / (samples - 1)
+    frames = [int(start + i * step) for i in range(samples)]
+
+(outdir / "timestamps.txt").write_text(
+    "\n".join(f"{f / fps:.3f}" for f in frames) + "\n"
+)
+
+# select='eq(n,F1)+eq(n,F2)+...' picks exactly the listed frames from each
+# input. We then hstack per-frame pairs and vstack the result.
+select_expr = "+".join(f"eq(n,{f})" for f in frames)
+n = len(frames)
+filter_parts = [
+    f"[0:v]select='{select_expr}',setpts=N/FRAME_RATE/TB,split={n}"
+    + "".join(f"[b{i}]" for i in range(n)),
+    f"[1:v]select='{select_expr}',setpts=N/FRAME_RATE/TB,split={n}"
+    + "".join(f"[t{i}]" for i in range(n)),
+]
+for i in range(n):
+    filter_parts.append(f"[b{i}][t{i}]hstack=inputs=2[row{i}]")
+filter_parts.append(
+    "".join(f"[row{i}]" for i in range(n)) + f"vstack=inputs={n}[out]"
+)
+filter_graph = ";".join(filter_parts)
+
+cmd = [
+    "ffmpeg", "-y", "-hide_banner", "-loglevel", "error",
+    "-i", baseline, "-i", translated,
+    "-filter_complex", filter_graph,
+    "-map", "[out]", "-frames:v", "1",
+    str(outdir / "strip.png"),
+]
+subprocess.run(cmd, check=True)
+print(f"wrote {outdir / 'strip.png'} ({n} samples)")
+PY