macOS DMG: branded window background and icon layout

The DMG opened as a plain Finder window. It now shows the app icon's figure on
the GridCraft colour, with GridCraft.app and the Applications link side by side.
Same approach as PhotoCraft's and VectorCraft's (storytold/photocraft#1201,
storytold/vectorcraft#493).

- packaging/macos/dmg/: background.svg (source; text outlined, no paper grain,
  the figure an <image> of assets/app-icon), background.tiff (1x + 2x HiDPI,
  16-colour palette, Deflate, sRGB; ~26 KB)
  and dmg-layout.DS_Store (Finder view settings: window, icon size 128,
  positions, background).
- generate.py writes the TIFF and the layout on any OS, byte-for-byte
  reproducible, with nothing from the machine that ran it (no paths, users,
  disk names or volume UUIDs).
- package.sh copies them into the staging folder; the image is still built with
  hdiutil makehybrid. Nothing extra runs in the signing job.
- The volume name drops the version: the layout finds the background through
  an alias that includes the volume name. The DMG file name keeps the version.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ATTRIBUTION.md

@@ -18,6 +18,8 @@ Generated-in-code art is original and has no file to list: the UI icon set (`cra
 | `docs/brand/artcraft-mark-black.png` | ArtCraft Team | craftrules `assets/brand/` | ArtCraft brand terms | Trademark |
 | `docs/brand/LICENSE-brand.txt` | (licence text) | craftrules | — | |
 | `assets/app-icon/gridcraft.svg` | GridCraft contributors | original (hand-written SVG; `packaging/icons.sh`) | MIT OR Apache-2.0 (`assets/app-icon/LICENSE.txt`) | PLACEHOLDER app icon (ledger page); replaced by the owner's creature art later |
+| `packaging/macos/dmg/background.svg` | @XusBadia | original (hand-written SVG, derived from the GridCraft app icon `assets/app-icon/gridcraft.svg`, referenced via `<image>`, not copied; text is outlined glyph paths; `packaging/macos/dmg/generate.py` renders it to `background.tiff`) | MIT OR Apache-2.0 (`LICENSE-MIT`, `LICENSE-APACHE`) | GridCraft macOS DMG window background for the Finder window; added 2026-10-08 |
+| `packaging/macos/dmg/background.tiff` | @XusBadia | Rendered from `packaging/macos/dmg/background.svg` by `packaging/macos/dmg/generate.py` | MIT OR Apache-2.0 (`LICENSE-MIT`, `LICENSE-APACHE`) | 1x + 2x HiDPI TIFF for the macOS DMG window; includes the app icon (see its row) and LittleCMS's built-in sRGB profile ("No copyright, use freely") |
 | `assets/app-icon/gridcraft-1024.png` | GridCraft contributors | original (hand-written SVG; `packaging/icons.sh`) | MIT OR Apache-2.0 (`assets/app-icon/LICENSE.txt`) | Placeholder icon, rendered from gridcraft.svg |
 | `assets/app-icon/gridcraft-macos-512.png` | GridCraft contributors | original (hand-written SVG; `packaging/icons.sh`) | MIT OR Apache-2.0 (`assets/app-icon/LICENSE.txt`) | Placeholder icon, macOS grid render |
 | `assets/app-icon/gridcraft.icns` | GridCraft contributors | original (hand-written SVG; `packaging/icons.sh`) | MIT OR Apache-2.0 (`assets/app-icon/LICENSE.txt`) | Placeholder icon, macOS bundle icon |

docs/releasing.md

@@ -101,6 +101,9 @@ and upload their artifacts, the environment refuses macOS and Windows, and no re
 - **Notarization:** the app is zipped and sent with `xcrun notarytool submit --wait`, then
   stapled. The DMG (with an `Applications` link) is signed, notarized and stapled too, and
   checked with `codesign --verify --strict`, `stapler validate` and `spctl -a -vvv`.
+  Its Finder window (background, icon size and positions) comes from
+  [`packaging/macos/dmg/`](../packaging/macos/dmg/README.md), and its volume is named `GridCraft`
+  without the version, which the window's background needs; the DMG file name keeps the version.
 - **CLI:** the universal `gridcraft-cli` is signed, zipped and notarized.
 
 Locally, without certificates, the script signs ad-hoc (`codesign -s -`) and skips notarization:

packaging/macos/dmg/README.md

@@ -0,0 +1,44 @@
+# macOS DMG window
+
+What Finder shows when the DMG opens: a 660 × 400 pt background with the app icon and the
+`Applications` link side by side. `package.sh` copies these files into the image; nothing here is
+generated at build time, so the DMG still builds with `hdiutil makehybrid` (no mounted device, no
+Finder scripting on CI, nothing extra installed in the signing job).
+
+| File | What |
+|---|---|
+| `background.svg` | Source of the background: the app icon (`assets/app-icon/gridcraft.svg`, linked, not copied) cropped as a cover on the GridCraft colour field (`#1f9d55`), Ink and Paper. Its text (Inter, JetBrains Mono) is outlined, so rendering it needs no fonts. No paper grain: noise doesn't compress, and this keeps `background.tiff` small. |
+| `background.tiff` | The background at 1x (660 × 400 px, 72 dpi) and 2x (1320 × 800 px, 144 dpi) in one HiDPI TIFF (16-colour palette, Deflate, sRGB). Goes to `.background/background.tiff`. |
+| `dmg-layout.DS_Store` | Finder's view settings for the volume: window size, icon size 128, GridCraft.app at (326, 205), `Applications` at (574, 205), and the background. Goes to `.DS_Store` in the image; named so it isn't mistaken for (or ignored like) a Finder-generated `.DS_Store`. |
+| `generate.py` | Writes `background.tiff` and `dmg-layout.DS_Store` from the SVG and the layout above. |
+
+## The volume name has no version
+
+The mounted volume is called `GridCraft`, not `GridCraft <version>`. The layout points at the background
+through an alias that includes the volume name, and Finder resolves it by that name: with a
+versioned name the window keeps its size and icon positions but shows no background (tested).
+The DMG file name (`gridcraft-<version>-macos-<arch>.dmg`) still carries the version.
+
+## Rules
+
+- **Finder draws the icon labels in black in light and dark mode** when a window has a background,
+  so the area under both icons stays light (Paper).
+- **Nothing goes inside the icon boxes:** artwork keeps 10 pt clear of each 128 pt icon box and of
+  the label strip under it.
+
+## Regenerate
+
+Edit `background.svg` (or the layout constants in `generate.py`), then run, on any OS:
+
+```sh
+pip install 'pillow>=12' ds_store==1.3.3 mac_alias==2.2.3
+python3 packaging/macos/dmg/generate.py   # needs resvg on PATH
+```
+
+Both outputs are byte-for-byte reproducible and carry nothing from the machine that ran it: the
+SVG renders without any fonts, and `dmg-layout.DS_Store` is written from scratch, its background
+alias holding only the volume name and `/.background/background.tiff`. If you add text to the SVG,
+outline it (`usvg` from resvg converts text to paths). The window is 660 × 432 with Finder's 32 pt
+title bar; the content area is 660 × 400.
+
+This follows VectorCraft's `packaging/macos/dmg/` (storytold/vectorcraft#493).

packaging/macos/dmg/generate.py

@@ -0,0 +1,158 @@
+#!/usr/bin/env python3
+"""Regenerate background.tiff and dmg-layout.DS_Store for the macOS DMG window (see README.md here).
+
+Needs resvg on PATH and:
+    pip install 'pillow>=12' ds_store==1.3.3 mac_alias==2.2.3
+
+Runs on any OS, no Mac needed. Both outputs come from this script alone, so they carry nothing
+from the machine that made them: no local paths, user or disk names, dates or volume UUIDs.
+
+    python3 packaging/macos/dmg/generate.py
+"""
+
+import datetime
+import os
+import shutil
+import subprocess
+import sys
+import tempfile
+
+from ds_store import DSStore
+from mac_alias import Alias, TargetInfo, VolumeInfo
+from PIL import Image, ImageCms
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+
+# Keep in sync with package.sh (volume name) and README.md (layout).
+VOLUME = "GridCraft"
+WIDTH, HEIGHT = 660, 400  # window content, pt; the background's 1x size
+TITLE_BAR = 32
+ICON_SIZE = 128
+PALETTE = 16  # colours in background.tiff
+ICONS = {"GridCraft.app": (326, 205), "Applications": (574, 205)}
+# A fixed date for the alias and the colour profile. Finder never matches it against the image
+# (each build is a new volume): it finds the background by volume name and path.
+FIXED_DATE = datetime.datetime(2026, 10, 8, tzinfo=datetime.timezone.utc)
+
+
+def render(svg, width, out):
+    # The SVG's text is already outlined and no fonts are loaded, so every machine draws the
+    # same pixels.
+    subprocess.run(
+        ["resvg", "--skip-system-fonts", "-w", str(width), svg, out],
+        check=True,
+    )
+    with Image.open(out) as im:
+        return im.convert("RGB")
+
+
+def quantize(im):
+    # No dithering: dither noise compresses badly and the artwork has flat fills.
+    return im.quantize(PALETTE, method=Image.Quantize.FASTOCTREE, dither=Image.Dither.NONE)
+
+
+def srgb_profile():
+    # LittleCMS's built-in sRGB ("No copyright, use freely"), with its creation date fixed.
+    icc = bytearray(ImageCms.ImageCmsProfile(ImageCms.createProfile("sRGB")).tobytes())
+    d = FIXED_DATE
+    icc[24:36] = b"".join(v.to_bytes(2, "big") for v in (d.year, d.month, d.day, 0, 0, 0))
+    if icc[84:100] != bytes(16):
+        sys.exit("error: the sRGB profile has an ID; recompute it after fixing the date")
+    return bytes(icc)
+
+
+def write_tiff(svg, out):
+    """1x (72 dpi) and 2x (144 dpi) in one TIFF, as `tiffutil -cathidpicheck` writes them."""
+    with tempfile.TemporaryDirectory() as tmp:
+        one, two = (
+            quantize(render(svg, WIDTH * s, os.path.join(tmp, f"{s}x.png"))) for s in (1, 2)
+        )
+    two.encoderinfo = {"dpi": (144, 144)}  # the rest as the first page
+    # Opaque 16-colour palette, Deflate: the artwork is three inks plus antialiasing, and a palette
+    # keeps the file under ~100 KB (repository assets must stay small). As PhotoCraft's.
+    one.save(
+        out,
+        "TIFF",
+        save_all=True,
+        append_images=[two],
+        compression="tiff_adobe_deflate",  # brand-ok: Pillow's name for TIFF compression 8 (Deflate)
+        dpi=(72, 72),
+        icc_profile=srgb_profile(),
+    )
+    with Image.open(out) as im:
+        im.seek(1)
+        if im.info.get("dpi") != (144, 144):
+            sys.exit("error: the 2x page isn't 144 dpi (needs Pillow 12 or later)")
+        strips = []
+        for page in (0, 1):
+            im.seek(page)
+            strips += zip(im.tag_v2[273], im.tag_v2[279])  # StripOffsets, StripByteCounts
+    # TIFF keeps directories and tag data on even offsets. When a strip ends on an odd one, libtiff
+    # leaves the padding byte after it uninitialised, so the file changed from run to run with
+    # identical pixels. Zero it: nothing refers to that byte.
+    starts = {o for o, _ in strips}
+    with open(out, "r+b") as f:
+        for o, n in strips:
+            if (o + n) % 2 and o + n not in starts:
+                f.seek(o + n)
+                f.write(bytes(1))
+
+
+def background_alias():
+    # What Finder stores for /.background/background.tiff on the volume, minus anything about the
+    # machine (dmgbuild writes the same kind of alias from a mounted image). Disk type 5 (ejectable),
+    # the volume flags and the folder/file ids (25, 26) are what Finder wrote on a test image; the ids
+    # are only hints, as the volume's creation date.
+    volume = VolumeInfo(VOLUME, FIXED_DATE, b"H+", 5, 0x0D02, b"\0\0")
+    volume.posix_path = f"/Volumes/{VOLUME}"
+    target = TargetInfo(0, "background.tiff", 25, 26, FIXED_DATE, b"\0\0\0\0", b"\0\0\0\0")
+    target.folder_name = ".background"
+    target.cnid_path = [25]
+    target.carbon_path = f"{VOLUME}:.background:\0background.tiff"
+    target.posix_path = "/.background/background.tiff"
+    return Alias(volume=volume, target=target).to_bytes()
+
+
+def write_ds_store(out):
+    if os.path.exists(out):
+        os.remove(out)
+    with DSStore.open(out, "w+") as d:
+        d["."]["bwsp"] = {
+            "ShowStatusBar": False,
+            "ShowToolbar": False,
+            "ShowTabView": False,
+            "ContainerShowSidebar": False,
+            "ShowSidebar": False,
+            "WindowBounds": f"{{{{200, 528}}, {{{WIDTH}, {HEIGHT + TITLE_BAR}}}}}",
+        }
+        d["."]["icvp"] = {
+            "viewOptionsVersion": 1,
+            "backgroundType": 2,
+            "backgroundImageAlias": background_alias(),
+            "backgroundColorRed": 1.0,
+            "backgroundColorGreen": 1.0,
+            "backgroundColorBlue": 1.0,
+            "gridOffsetX": 0.0,
+            "gridOffsetY": 0.0,
+            "gridSpacing": 100.0,
+            "arrangeBy": "none",
+            "showIconPreview": True,
+            "showItemInfo": False,
+            "labelOnBottom": True,
+            "textSize": 16.0,
+            "iconSize": float(ICON_SIZE),
+        }
+        d["."]["vSrn"] = ("long", 1)
+        for name, pos in ICONS.items():
+            d[name]["Iloc"] = pos
+
+
+def main():
+    if not shutil.which("resvg"):
+        sys.exit("error: resvg not found (brew install resvg / cargo install resvg --locked)")
+    write_tiff(os.path.join(HERE, "background.svg"), os.path.join(HERE, "background.tiff"))
+    write_ds_store(os.path.join(HERE, "dmg-layout.DS_Store"))
+
+
+if __name__ == "__main__":
+    main()

packaging/macos/package.sh

@@ -131,10 +131,15 @@ STAGE="$WORK/dmg"
 mkdir -p "$STAGE"
 ditto "$APP" "$STAGE/GridCraft.app"
 ln -s /Applications "$STAGE/Applications"
+# Finder window layout: background, icon size and positions (packaging/macos/dmg/README.md).
+mkdir -p "$STAGE/.background"
+cp "$HERE/dmg/background.tiff" "$STAGE/.background/background.tiff"
+cp "$HERE/dmg/dmg-layout.DS_Store" "$STAGE/.DS_Store"
 rm -f "$DMG" "$WORK/raw.dmg"
 # makehybrid + convert builds the image without attaching a device, unlike `create -srcfolder`,
 # which is flaky on CI runners ("Resource busy") and hangs in sandboxed sessions.
-hdiutil makehybrid -hfs -hfs-volume-name "GridCraft $VERSION" -hfs-openfolder "$STAGE" -o "$WORK/raw.dmg" "$STAGE"
+# The volume name has no version: .DS_Store finds the background through an alias that includes it.
+hdiutil makehybrid -hfs -hfs-volume-name "GridCraft" -hfs-openfolder "$STAGE" -o "$WORK/raw.dmg" "$STAGE"
 hdiutil convert "$WORK/raw.dmg" -format UDZO -imagekey zlib-level=9 -o "$DMG"
 rm -f "$WORK/raw.dmg"
 sign "$DMG"