feat(scripts): make-demo-gif.sh — produce optimized README hero GIF (Closes #7)

scripts/make-demo-gif.sh

@@ -0,0 +1,106 @@
+#!/usr/bin/env bash
+# make-demo-gif.sh — turn a screen recording into a README-ready GIF.
+#
+# Usage:
+#   scripts/make-demo-gif.sh <input.mov> [output.gif]
+#
+# Defaults:
+#   output         docs/screenshots/flow-editor.gif
+#   trim           first 15 s of the recording
+#   width          900 px (preserves aspect ratio)
+#   fps            15 (good motion-to-size tradeoff for UI demos)
+#   palette        gifski's perceptual quantizer (preferred), or
+#                  ffmpeg's two-pass palettegen+paletteuse (fallback)
+#
+# Why this script: we want the README hero GIF to look sharp without
+# blowing past the 10 MiB GitHub asset soft-limit. Gifski is markedly
+# better than ffmpeg's GIF encoder for UI screen captures, but isn't
+# always installed; ffmpeg almost always is. Both branches go through
+# the same trim+scale ffmpeg first stage so the input format/codec
+# doesn't matter.
+
+set -euo pipefail
+
+if [[ $# -lt 1 ]]; then
+    echo "usage: $0 <input.mov> [output.gif]" >&2
+    echo "  default output: docs/screenshots/flow-editor.gif" >&2
+    exit 1
+fi
+
+INPUT="$1"
+OUTPUT="${2:-docs/screenshots/flow-editor.gif}"
+DURATION="${DURATION:-15}"
+WIDTH="${WIDTH:-900}"
+FPS="${FPS:-15}"
+TARGET_MAX_MB="${TARGET_MAX_MB:-10}"
+
+if [[ ! -f "$INPUT" ]]; then
+    echo "❌ input not found: $INPUT" >&2
+    exit 1
+fi
+
+if ! command -v ffmpeg >/dev/null 2>&1; then
+    echo "❌ ffmpeg not found. Install it:" >&2
+    echo "   macOS:  brew install ffmpeg" >&2
+    echo "   debian: apt install ffmpeg" >&2
+    exit 1
+fi
+
+mkdir -p "$(dirname "$OUTPUT")"
+
+WORK_DIR="$(mktemp -d -t make-demo-gif.XXXXXX)"
+trap 'rm -rf "$WORK_DIR"' EXIT
+
+INTERMEDIATE_MP4="$WORK_DIR/trimmed.mp4"
+
+say() { printf "\n\033[1;36m==> %s\033[0m\n" "$*"; }
+
+# ── 1. Trim + scale + drop audio ─────────────────────────────────────
+say "Trim to ${DURATION}s, scale width to ${WIDTH}, fps=${FPS}"
+ffmpeg -hide_banner -loglevel warning -y \
+    -i "$INPUT" \
+    -t "$DURATION" \
+    -vf "scale=${WIDTH}:-2:flags=lanczos,fps=${FPS}" \
+    -an \
+    -c:v libx264 -preset slow -crf 18 \
+    "$INTERMEDIATE_MP4"
+
+# ── 2. Encode GIF — gifski (preferred) or ffmpeg palettegen ──────────
+if command -v gifski >/dev/null 2>&1; then
+    say "Encoding GIF with gifski (high quality)"
+    # gifski needs frames; pull them out first.
+    FRAMES_DIR="$WORK_DIR/frames"
+    mkdir -p "$FRAMES_DIR"
+    ffmpeg -hide_banner -loglevel warning -y \
+        -i "$INTERMEDIATE_MP4" \
+        "$FRAMES_DIR/frame-%05d.png"
+    gifski --fps "$FPS" --width "$WIDTH" --quality 90 \
+           -o "$OUTPUT" "$FRAMES_DIR"/frame-*.png
+else
+    say "Encoding GIF with ffmpeg palettegen+paletteuse (gifski not installed; brew install gifski for better quality)"
+    PALETTE="$WORK_DIR/palette.png"
+    ffmpeg -hide_banner -loglevel warning -y \
+        -i "$INTERMEDIATE_MP4" \
+        -vf "palettegen=stats_mode=diff" \
+        "$PALETTE"
+    ffmpeg -hide_banner -loglevel warning -y \
+        -i "$INTERMEDIATE_MP4" -i "$PALETTE" \
+        -filter_complex "paletteuse=dither=bayer:bayer_scale=5:diff_mode=rectangle" \
+        "$OUTPUT"
+fi
+
+# ── 3. Report size + warn if over target ─────────────────────────────
+SIZE_BYTES=$(stat -f%z "$OUTPUT" 2>/dev/null || stat -c%s "$OUTPUT")
+SIZE_MB=$(awk "BEGIN {printf \"%.2f\", $SIZE_BYTES / 1024 / 1024}")
+say "Wrote $OUTPUT (${SIZE_MB} MiB)"
+
+if (( $(awk "BEGIN {print ($SIZE_MB > $TARGET_MAX_MB)}") )); then
+    cat >&2 <<EOF
+
+⚠ GIF is ${SIZE_MB} MiB — above the ${TARGET_MAX_MB} MiB soft limit.
+  Try one of:
+    DURATION=10 $0 "$INPUT" "$OUTPUT"     # shorter clip
+    WIDTH=720   $0 "$INPUT" "$OUTPUT"     # narrower
+    FPS=12      $0 "$INPUT" "$OUTPUT"     # fewer frames
+EOF
+fi