Add low-res icon QA exports

Scripts/check-brand-icon-lowres.sh

@@ -0,0 +1,108 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+cd "$repo_root"
+
+ictool="/Applications/Xcode/Xcode.app/Contents/Applications/Icon Composer.app/Contents/Executables/ictool"
+icon_doc="$repo_root/design/brand/Burrow.icon"
+output_dir_arg="${1:-design/brand/low-res}"
+if [[ "$output_dir_arg" = /* ]]; then
+  output_dir="$output_dir_arg"
+else
+  output_dir="$repo_root/$output_dir_arg"
+fi
+master="$output_dir/burrow-icon-1024.png"
+checked_in_master="$repo_root/design/brand/burrow-owl-icon-master.png"
+source_master="$checked_in_master"
+sizes=(16 20 24 29 32 40 48 64 80 128 256)
+
+require_tool() {
+  if ! command -v "$1" >/dev/null 2>&1; then
+    echo "error: required tool not found: $1" >&2
+    exit 127
+  fi
+}
+
+require_tool magick
+require_tool awk
+
+if [[ ! -x "$ictool" ]]; then
+  echo "error: Icon Composer ictool not found at $ictool" >&2
+  exit 127
+fi
+
+mkdir -p "$output_dir"
+
+if [[ "${BURROW_ICON_REFRESH:-0}" == "1" ]]; then
+  if ! "$ictool" "$icon_doc" \
+    --export-image \
+    --output-file "$master" \
+    --platform iOS \
+    --rendition Default \
+    --width 1024 \
+    --height 1024 \
+    --scale 1 >/dev/null; then
+    echo "warning: ictool could not export $icon_doc; falling back to $checked_in_master" >&2
+    magick "$checked_in_master" -colorspace sRGB -strip "PNG24:$master"
+    source_master="$checked_in_master"
+  else
+    source_master="$master"
+  fi
+else
+  magick "$checked_in_master" -colorspace sRGB -strip "PNG24:$master"
+fi
+
+printf "size,colors,gray_stddev,status\n" >"$output_dir/report.csv"
+
+for size in "${sizes[@]}"; do
+  image="$output_dir/burrow-icon-${size}.png"
+  magick "$source_master" -colorspace sRGB -resize "${size}x${size}!" -strip "PNG24:$image"
+
+  actual="$(magick "$image" -format "%wx%h" info:)"
+  if [[ "$actual" != "${size}x${size}" ]]; then
+    echo "error: $image rendered as $actual, expected ${size}x${size}" >&2
+    exit 1
+  fi
+
+  colors="$(magick "$image" -format "%k" info:)"
+  stddev="$(magick "$image" -colorspace Gray -format "%[fx:standard_deviation]" info:)"
+  min_colors=$((size * 4))
+  if (( min_colors < 48 )); then
+    min_colors=48
+  fi
+  if (( min_colors > 900 )); then
+    min_colors=900
+  fi
+
+  awk -v size="$size" -v colors="$colors" -v min_colors="$min_colors" -v stddev="$stddev" '
+    BEGIN {
+      if (colors < min_colors) {
+        printf "error: %dpx icon has only %d colors; expected at least %d\n", size, colors, min_colors > "/dev/stderr";
+        exit 1;
+      }
+      if (stddev < 0.08) {
+        printf "error: %dpx icon grayscale stddev is %.6f; expected at least 0.08\n", size, stddev > "/dev/stderr";
+        exit 1;
+      }
+    }
+  '
+
+  printf "%s,%s,%s,ok\n" "$size" "$colors" "$stddev" >>"$output_dir/report.csv"
+done
+
+preview_inputs=()
+for size in 256 128 80 64 48 40 32 29 20 16; do
+  preview="$output_dir/preview-${size}.png"
+  if (( size <= 20 )); then
+    filter=Point
+  else
+    filter=Lanczos
+  fi
+  magick "$output_dir/burrow-icon-${size}.png" -filter "$filter" -resize 128x128 "$preview"
+  preview_inputs+=("$preview")
+done
+
+magick -background "#202020" -gravity center "${preview_inputs[@]}" +append "$output_dir/preview-strip.png"
+
+echo "low-res icon exports written to $output_dir"