fix(ci): pin GitHub Actions to macos-14 and keep the window on-screen

macos-latest is macos-26-arm64 (run 34864198118). A 1280x800 window
centered on that display hangs off the left edge, so XCTest sees
sidebar controls at x ≈ -116 and refuses the click. Pin the GitHub
workflow to macos-14 and clamp the main window to visibleFrame.

.gitea/workflows/macos.yml

@@ -35,7 +35,8 @@ jobs:
       # The job still succeeds quickly so `package`'s `needs:` stays satisfied.
       # Homebrew's xcodegen formula requires Xcode 15.3, which cannot be
       # installed on macOS 12 (#109). The script installs a pinned
-      # prebuilt release instead.
+      # prebuilt release instead. dmgbuild is not installed here — the
+      # test job does not package (#95).
       - name: Ensure host tools
         if: "!(startsWith(github.ref, 'refs/tags/') && contains(github.ref_name, 'prerelease'))"
         run: scripts/ensure-host-tools.sh
@@ -193,8 +194,10 @@ jobs:
 
       # scripts/package-release.sh runs `xcodegen generate` and dmgbuild;
       # see build-and-test for why brew is not used on macOS 12 (#109).
+      # INSTALL_DMGBUILD isolates dmgbuild in build/.venv-dmgbuild so
+      # the test job never pip-installs it (#95).
       - name: Ensure host tools
-        run: scripts/ensure-host-tools.sh
+        run: INSTALL_DMGBUILD=1 scripts/ensure-host-tools.sh
 
       - name: Package release
         run: scripts/package-release.sh

.github/workflows/macos.yml

@@ -0,0 +1,231 @@
+# GitHub Actions twin of .gitea/workflows/macos.yml.
+# Deltas from the Gitea file (everything else is the same jobs/steps):
+#   - runs-on macos-14: github.com retired macos-12. Do not use
+#     macos-latest — in 2026 that is macos-26-arm64, where a 1280×800
+#     window hangs off the virtual display and XCTest marks sidebar
+#     controls (x ≈ -116) as not hittable (run 34864198118).
+#   - actions/upload-artifact@v4: v3 is shut down on github.com. Gitea act_runner
+#     still uses v3.
+#   - No NODE_EXTRA_CA_CERTS / System keychain bundle: that is only for the
+#     private Gitea CA when the runner talks to git.i3omb.com.
+#   - Tag DMGs go to a GitHub Release via `gh` instead of
+#     scripts/attach-release-asset.sh (Gitea /api/v1).
+name: macOS CI
+
+on:
+  push:
+    branches:
+      - develop
+    tags:
+      - 'v*'
+  pull_request:
+    branches:
+      - develop
+
+permissions:
+  contents: read
+
+jobs:
+  build-and-test:
+    runs-on: macos-14
+    env:
+      DERIVED: build/DerivedData-test
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Assert Xcode 14+ toolchain
+        run: |
+          line="$(xcodebuild -version | head -1)"
+          major="$(printf '%s' "$line" | sed -n 's/^Xcode \([0-9][0-9]*\)\..*/\1/p')"
+          if [ -z "$major" ] || [ "$major" -lt 14 ]; then
+            echo "Unexpected Xcode version: $line" >&2; exit 1
+          fi
+          echo "$line"
+
+      # Tag pushes whose name contains "prerelease" skip the test build and both
+      # test legs: they exist to package a build already validated elsewhere.
+      # The job still succeeds quickly so `package`'s `needs:` stays satisfied.
+      # Homebrew's xcodegen formula requires Xcode 15.3, which cannot be
+      # installed on macOS 12 (#109). The script installs a pinned
+      # prebuilt release instead. dmgbuild is not installed here — the
+      # test job does not package (#95).
+      - name: Ensure host tools
+        if: "!(startsWith(github.ref, 'refs/tags/') && contains(github.ref_name, 'prerelease'))"
+        run: scripts/ensure-host-tools.sh
+
+      - name: Generate Xcode project
+        if: "!(startsWith(github.ref, 'refs/tags/') && contains(github.ref_name, 'prerelease'))"
+        run: xcodegen generate --spec project.yml
+
+      # Tests only ever run on the runner's own architecture; build
+      # just that slice. Packaging (scripts/package-release.sh) still
+      # produces the universal Release binary.
+      - name: Build for testing (host arch)
+        if: "!(startsWith(github.ref, 'refs/tags/') && contains(github.ref_name, 'prerelease'))"
+        run: |
+          xcodebuild build-for-testing \
+            -scheme ICCery \
+            -destination 'platform=macOS' \
+            -derivedDataPath "$DERIVED" \
+            -configuration Debug \
+            ARCHS="$(uname -m)" \
+            ONLY_ACTIVE_ARCH=NO \
+            CODE_SIGNING_ALLOWED=YES \
+            CODE_SIGN_IDENTITY='-'
+
+      # Xcode embeds the shared ICCeryCore package framework into the app
+      # and the test bundle without signing it. Ad-hoc hosts still require
+      # every loaded dylib to carry a cdhash — dyld killed the test host at
+      # launch (run 31992) — so sign every embedded copy once the build is
+      # done (embed steps run after any build script phase) (#119).
+      - name: Sign package product frameworks
+        if: "!(startsWith(github.ref, 'refs/tags/') && contains(github.ref_name, 'prerelease'))"
+        run: |
+          find "$DERIVED/Build/Products/Debug" -depth -name '*_PackageProduct.framework' -print0 \
+            | while IFS= read -r -d '' fw; do
+                echo "signing $fw"
+                codesign --force --sign - --timestamp=none "$fw"
+              done
+
+      - name: Test unit (ICCeryCoreTests)
+        if: "!(startsWith(github.ref, 'refs/tags/') && contains(github.ref_name, 'prerelease'))"
+        run: |
+          XCTESTRUN="$(find "$DERIVED" -name 'ICCery*.xctestrun' | head -n 1)"
+          if [ -z "$XCTESTRUN" ] || [ ! -f "$XCTESTRUN" ]; then
+            echo "error: no xctestrun produced by build-for-testing" >&2
+            exit 1
+          fi
+          echo "xctestrun: $XCTESTRUN"
+          xcodebuild test-without-building \
+            -xctestrun "$XCTESTRUN" \
+            -only-testing:ICCeryCoreTests \
+            -destination 'platform=macOS' \
+            -derivedDataPath "$DERIVED"
+
+      # UI tests need macOS Automation / Accessibility permission on the
+      # runner. GitHub-hosted macos-14 images enable this; a self-hosted
+      # Mac can still time out enabling that mode (run 29700) or launch
+      # the app into `.runningBackground` (run 29804). Kill any leftover
+      # unit-test host first; retry once; if the runner still cannot
+      # attach, do not fail the required gate so tag packaging can
+      # proceed. Real XCTest assertion failures still fail the job.
+      - name: Test UI (ICCeryUITests)
+        if: "!(startsWith(github.ref, 'refs/tags/') && contains(github.ref_name, 'prerelease'))"
+        run: |
+          set -o pipefail
+          XCTESTRUN="$(find "$DERIVED" -name 'ICCery*.xctestrun' | head -n 1)"
+          LOG="$DERIVED/ui-test.log"
+          pkill -x ICCery 2>/dev/null || true
+          sleep 1
+
+          run_ui() {
+            local label="$1"
+            shift
+            echo "::group::UI tests $label"
+            set +e
+            xcodebuild test-without-building \
+              -xctestrun "$XCTESTRUN" \
+              -destination 'platform=macOS' \
+              -derivedDataPath "$DERIVED" \
+              "$@" | tee "$LOG"
+            rc=${PIPESTATUS[0]}
+            set -e
+            echo "::endgroup::"
+            return "$rc"
+          }
+
+          is_runner_attach_failure() {
+            grep -Eq "Timed out while enabling automation mode|Failed to activate application|current state: Running Background" "$LOG"
+          }
+
+          attempt=1
+          while [ "$attempt" -le 2 ]; do
+            # Probe one case first. A background-activate failure costs
+            # ~65s here instead of ~25 minutes for the whole suite (29804).
+            if ! run_ui "probe attempt $attempt" \
+                -only-testing:ICCeryUITests/AboutHelpUITests/testAboutDialogShowsVersionAndBuildDate; then
+              if is_runner_attach_failure; then
+                echo "warning: UI runner could not attach/activate the app (attempt $attempt)"
+                pkill -x ICCery 2>/dev/null || true
+                attempt=$((attempt + 1))
+                sleep 8
+                continue
+              fi
+              echo "error: UI probe failed with a real test error" >&2
+              exit 1
+            fi
+            if run_ui "full suite attempt $attempt" -only-testing:ICCeryUITests \
+                -skip-testing:ICCeryUITests/AboutHelpUITests/testAboutDialogShowsVersionAndBuildDate; then
+              exit 0
+            fi
+            if is_runner_attach_failure; then
+              echo "warning: UI runner lost activation mid-suite (attempt $attempt)"
+              pkill -x ICCery 2>/dev/null || true
+              attempt=$((attempt + 1))
+              sleep 8
+              continue
+            fi
+            echo "error: UI tests failed with a real test error" >&2
+            exit 1
+          done
+          echo "warning: skipping UI tests after repeated runner attach/activate failures"
+          exit 0
+
+      # XCTest stores the a11y hierarchy snapshot and screenshots in the
+      # xcresult on failure — upload it so UI failures can be triaged
+      # without access to the runner (#126).
+      - name: Upload UI test xcresult
+        if: "failure() && !(startsWith(github.ref, 'refs/tags/') && contains(github.ref_name, 'prerelease'))"
+        uses: actions/upload-artifact@v4
+        with:
+          name: ui-test-xcresult
+          path: build/DerivedData-test/Logs/Test
+
+  package:
+    needs: build-and-test
+    runs-on: macos-14
+    if: github.ref == 'refs/heads/develop' || startsWith(github.ref, 'refs/tags/v')
+    permissions:
+      contents: write
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      # scripts/package-release.sh runs `xcodegen generate` and dmgbuild;
+      # see build-and-test for why brew is not used on macOS 12 (#109).
+      # INSTALL_DMGBUILD isolates dmgbuild in build/.venv-dmgbuild so
+      # the test job never pip-installs it (#95).
+      - name: Ensure host tools
+        run: INSTALL_DMGBUILD=1 scripts/ensure-host-tools.sh
+
+      - name: Package release
+        run: scripts/package-release.sh
+        env:
+          CODESIGN_IDENTITY: ${{ secrets.CODESIGN_IDENTITY }}
+          DEVELOPMENT_TEAM: ${{ secrets.DEVELOPMENT_TEAM }}
+          NOTARIZE_APPLE_ID: ${{ secrets.NOTARIZE_APPLE_ID }}
+          NOTARIZE_PASSWORD: ${{ secrets.NOTARIZE_PASSWORD }}
+          APPLE_TEAM_ID: ${{ secrets.APPLE_TEAM_ID }}
+
+      - name: Upload DMG artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: iccery-dmg
+          path: ICCery-*.dmg
+
+      - name: Attach DMG to GitHub release
+        if: startsWith(github.ref, 'refs/tags/v')
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          set -eu
+          TAG="$GITHUB_REF_NAME"
+          case "$TAG" in
+            *prerelease*) PRE_FLAG=--prerelease ;;
+            *)            PRE_FLAG= ;;
+          esac
+          if ! gh release view "$TAG" >/dev/null 2>&1; then
+            gh release create "$TAG" --title "$TAG" --target "$GITHUB_SHA" $PRE_FLAG
+          fi
+          gh release upload "$TAG" ICCery-*.dmg --clobber

README.md

@@ -1,45 +1,75 @@
 # ICCery
 
-Native macOS frontend for printer ICC/ICM profiling. ICCery walks a user from chart generation through measurement, `colprof`, verification, and ColorSync install. It is **not** a colour engine.
+Native macOS frontend for printer ICC/ICM profiling. ICCery walks a user from
+chart generation through measurement, `colprof`, verification, and ColorSync
+install. It is **not** a colour engine.
 
-All measurement, chart generation, and profile mathematics live in the [Gronod ArgyllCMS 3.5.0 fork](https://git.i3omb.com/gronod/argyllcms), spawned as AGPLv3 child processes. The GUI never `dlopen`s or links Argyll.
+**End-user guide:** the [repository wiki](https://git.i3omb.com/gronod/iccery-v2-mac/wiki)
+covers every screen (Getting Started through Troubleshooting). This README is
+for building, packaging, and contributing.
+
+All measurement, chart generation, and profile mathematics live in the
+[Gronod ArgyllCMS 3.5.0 fork](https://git.i3omb.com/gronod/argyllcms), spawned
+as AGPLv3 child processes. The GUI never `dlopen`s or links Argyll.
 
 | | |
 |---|---|
 | Product | ICCery v2 for macOS |
 | Bundle | `com.gronod.iccery2` |
+| Version | 2.0.0 |
 | Floor | macOS 12.0 Monterey, universal `arm64` + `x86_64` |
+| Toolchain | Xcode 14.2 / Swift 5.7 (project `SWIFT_VERSION` is 5.0) |
+| CI | Gitea Actions `macos-12` runner |
 | Default branch | `develop` |
-| M6 | Stage 0 calibration, CGATS import, SceneKit gamut viewer, packaging — shipped on `develop` |
+| M6 | Stage 0 calibration, CGATS import, SceneKit gamut viewer, packaging — shipped |
-| M7 | Pre-UAT hardening & baseline consolidation — shipped on `develop` |
+| M7 | Pre-UAT hardening — shipped |
-| M8 | Deduplication/consolidation contracts & UAT-ready hardening (#79–#86) — shipped on `develop` |
+| M8 | Deduplication contracts & UAT-ready hardening (#79–#86) — shipped |
-| M9 | macOS 12 / Xcode 14.2 retarget — shipped on `develop` (PR #145) |
+| M9 | macOS 12 / Xcode 14.2 retarget (PR #145) — shipped |
-| M10 | Studio workflow (#146–#149) — in flight on `milestone/m10-studio` |
+| M10 | Studio workflow: gamut compare (#147), Spot Read (#148), project files (#149) shipped on `develop`; media library (#146) is in the tree, issue still open |
 | Licence | Proprietary source in [`LICENCE.md`](LICENCE.md); bundled Argyll sidecars remain AGPLv3 |
 
 ## What it does
 
 The wizard is artefact-gated:
 
-1. **Stage 0** — printer calibration: `printcal` / `applycal` session, `CAL_` basename restore
+1. **Stage 1** — `targen` → `.ti1`
-2. **Stage 1** — `targen` → `.ti1`
+2. **Stage 2** — `printtarg` → `.ti2` + TIFF, unmanaged `lp` spool, bound `NSPrintPanel`
-3. **Stage 2** — `printtarg` → `.ti2` + TIFF, unmanaged `lp` spool, bound `NSPrintPanel`
+3. **Stage 3** — `instlist` + streaming `chartread` (strip / XY / handheld) → `.ti3`, multi-pass average, CIEDE2000
-4. **Stage 3** — `instlist` + streaming `chartread` (strip / XY / handheld) → `.ti3`, multi-pass average, CIEDE2000
+4. **Stage 4** — `colprof` → `.icc` / `.icm`; optional `applycal`; `iccgamut` next to the profile
-5. **Stage 4** — `colprof` → `.icc` / `.icm`; optional `applycal`; `iccgamut` next to the profile
+5. **Stage 5** — `profcheck`, verification history, ColorSync user/system install
-6. **Stage 5** — `profcheck`, verification history, ColorSync user/system install
 
-Plus CGATS dataset import (`.ti3` / `.txt` / `.cgats` / `.csv`), SceneKit gamut preview with sRGB overlay, and signed `.dmg` packaging.
+Plus:
 
-**Not this product:** display calibration (`dispwin` / `dispread`), i18n, Windows/Linux print trees, in-process Argyll, App Sandbox.
+- **Calibrate Printer** — optional `printcal` / `applycal` session under a `CAL_` basename
+- **CGATS import** — `.ti3` / `.txt` / `.cgats` / `.csv`
+- **Media recipes and presets** — printer + paper + ink bound to a preset and optional `.cal`
+- **Spot Read** — live one-patch Lab/XYZ from the instrument
+- **Project files** — `.icceryproj` bookmark over folder, basename, recipe, last ΔE
+- **Gamut viewer** — SceneKit Lab hull, sRGB overlay, second-profile compare, click-inspect
+- **Settings** — default instrument, ΔE good/warning cutoffs, install location, logging
+- Signed `.dmg` packaging with a HiDPI Finder background (Monterey through Sonoma)
+
+**Not this product:** display calibration (`dispwin` / `dispread`), i18n,
+Windows/Linux print trees, in-process Argyll, App Sandbox.
 
 ## Requirements
 
-- macOS 14+
+To **run** a packaged build:
-- Xcode 15.4+ with the macOS 14 SDK and Swift 6.0
-- [XcodeGen](https://github.com/yonaskolb/XcodeGen)
-- Network once, to fetch Argyll sidecars
 
-App Sandbox is **off**. Hardened Runtime is **on**. Entitlements live in `ICCery.entitlements`.
+- macOS 12.0 Monterey or later (Intel or Apple silicon)
+
+To **build** on the supported CI/host floor:
+
+- macOS 12 with **Xcode 14.2** (macOS 12 SDK, Swift 5.7)
+- [XcodeGen](https://github.com/yonaskolb/XcodeGen) **2.38.0** (Homebrew’s current
+  formula needs Xcode 15.3; CI installs the pinned zip via
+  `scripts/ensure-host-tools.sh`)
+- Network once, to fetch Argyll sidecars
+- For DMGs: Python 3.9+ and `dmgbuild==1.6.7` in `build/.venv-dmgbuild`
+  (`INSTALL_DMGBUILD=1 scripts/ensure-host-tools.sh`)
+
+App Sandbox is **off**. Hardened Runtime is **on**. Entitlements live in
+`ICCery.entitlements`.
 
 ## Build
 
@@ -49,7 +79,7 @@ cd iccery-v2-mac
 git checkout develop
 
 make fetch-argyll          # Vendor/Argyll/macos-universal/, ad-hoc signed
-make test                  # xcodegen + xcodebuild build test
+make test                  # xcodegen + xcodebuild build test (host arch)
 make universal             # ARCHS='arm64 x86_64' ONLY_ACTIVE_ARCH=NO
 ```
 
@@ -62,9 +92,14 @@ xcodebuild test -scheme ICCery \
   ARCHS="$(uname -m)"
 ```
 
-`project.yml` sets `ARCHS: "$(ARCHS_STANDARD)"`, so a plain `xcodebuild test` (and `make test`) builds universal; the `ARCHS="$(uname -m)"` override narrows it to the host slice.
+`project.yml` sets `ARCHS: "$(ARCHS_STANDARD)"`. CI and `make test` override
+that with `ARCHS="$(uname -m)"` so unit/UI tests build the host slice only.
+Fat binaries are `make universal` / `scripts/package-release.sh`.
 
-Sidecars are **not** in git. `scripts/fetch-argyll.sh` pulls the latest (or `ARGYLL_RELEASE_TAG`) macOS-universal release from `gronod/argyllcms`, extracts to `Vendor/Argyll/macos-universal/`, ad-hoc signs every Mach-O, and fails if `codesign -dvv` or the `instlist` marker is missing.
+Sidecars are **not** in git. `scripts/fetch-argyll.sh` pulls the latest (or
+`ARGYLL_RELEASE_TAG`) macOS-universal release from `gronod/argyllcms`, extracts
+to `Vendor/Argyll/macos-universal/`, ad-hoc signs every Mach-O, and fails if
+`codesign -dvv` or the `instlist` marker is missing.
 
 ```bash
 # optional
@@ -74,9 +109,11 @@ export ARGYLL_RELEASE_TAG=…    # default: latest
 export GITEA_TOKEN=…           # private releases
 ```
 
-`make clean` drops `ICCery.xcodeproj`, `DerivedData`, and `Packages/ICCeryCore/.build`.
+`make clean` drops `ICCery.xcodeproj`, `DerivedData`, and
+`Packages/ICCeryCore/.build`.
 
-Do not open the generated xcodeproj as the source of truth. Edit `project.yml` and regenerate.
+Do not open the generated xcodeproj as the source of truth. Edit `project.yml`
+and regenerate.
 
 ## Release packaging
 
@@ -84,11 +121,20 @@ Do not open the generated xcodeproj as the source of truth. Edit `project.yml` a
 scripts/package-release.sh    # fetch → sign → universal build → verify → DMG
 ```
 
-The script builds with a fixed derived data path (`build/DerivedData`),
+The script builds with a fixed derived data path (`build/DerivedData`), locates
-locates `Release/ICCery.app` from it, signs the bundle, recursively verifies
+`Release/ICCery.app` from it, signs the bundle, recursively verifies every
-every bundled Mach-O sidecar (`scripts/verify-sidecar-signatures.sh`), and
+bundled Mach-O sidecar (`scripts/verify-sidecar-signatures.sh`), builds a
-writes `ICCery-${VERSION}-${BUILD_NUM}.dmg` via `dmgbuild`. Sidecars stay
+HiDPI TIFF from `Resources/dmg-background.png` (+ `@2x`) via `tiffutil`, and
-ad-hoc signed inside the bundle — the app is never `codesign --deep`ed.
+writes `ICCery-${VERSION}-${BUILD_NUM}.dmg` with `dmgbuild==1.6.7`.
+
+Sidecars stay ad-hoc signed inside the bundle — the app is never
+`codesign --deep`ed.
+
+`dmgbuild` is **not** a test-job dependency. The package job sets
+`INSTALL_DMGBUILD=1` so `scripts/ensure-host-tools.sh` creates
+`build/.venv-dmgbuild`. On the Monterey runner (Python 3.9) that install uses
+`PIP_IGNORE_REQUIRES_PYTHON=1` and pins `pip>=24.3,<26.1` (pip 26.1+ needs
+3.10). Missing background art is a hard fail (#95).
 
 Environment variables read by the pipeline:
 
@@ -110,30 +156,47 @@ Resources/                 assets; Argyll reference files (not the tools)
 Vendor/Argyll/             fetched sidecars (gitignored)
 Tests/ICCeryCoreTests/     argv goldens, parsers, stores
 Tests/ICCeryUITests/       fixture / mock-binary UI tests
+scripts/ensure-host-tools.sh
 scripts/fetch-argyll.sh
+scripts/package-release.sh
 docs/                      functional spec + v2 ticket plan
 ```
 
-`ICCeryPrintKit` (issue #16, Quartz / AirPrint / TargetPrint) is v2.1 and is not in this tree.
+`ICCeryPrintKit` (issue #16, Quartz / AirPrint / TargetPrint) is v2.1 and is
+not in this tree.
 
 ## Architecture
 
-- **Spawn, never link.** Tools resolve through `BinaryResolver` inside the bundle / `Vendor` tree. `$PATH` is not searched. `ARGYLL_NOT_INTERACTIVE=1` is always set.
+- **Spawn, never link.** Tools resolve through `BinaryResolver` inside the
-- **`ProcessManager` actor** owns child lifetime. Streaming tools (`chartread`, `printcal`, etc.) use the event bus; one-shot tools use `runCaptured`. Exclusive `ProcessID` leases. Quit path: `q\n`, ~500 ms, kill; `killAll` on terminate.
+  bundle / `Vendor` tree. `$PATH` is not searched. `ARGYLL_NOT_INTERACTIVE=1`
-- **Argv builders** in ICCeryCore (`TargenArgs`, `PrinttargArgs`, `ChartreadArgs`, `ColprofArgs`, `ApplycalArgs`, `IccgamutArgs`, `ProfcheckArgs`, `LpArgs`, …). UI must not concatenate flags.
+  is always set.
-- **Atomic artefacts.** Writes go to `*.tmp` then `replaceItemAt`. `applycal` must not replace the input profile on cancel or non-zero exit.
+- **`ProcessManager` actor** owns child lifetime. Streaming tools
-- **Concurrency.** View models are `@MainActor`. No blocking I/O on the main actor. SwiftUI `@Observable` for new state.
+  (`chartread`, `printtarg`, `colprof`, …) use the event bus; one-shot tools
-- **Print.** Unmanaged `lp` with ColorSync suppression (`AP_ColorMatchingMode` / `AP.ColorMatchingMode`). Captured `NSPrintPanel` options win over derived CUPS keys. Never `lp -o raw`.
+  (`printcal`, `applycal`, CUPS) use `runCaptured`. Exclusive `ProcessID`
+  leases. Quit path: `q\n`, ~500 ms, kill; `killAll` on terminate.
+- **Argv builders** in ICCeryCore (`TargenArgs`, `PrinttargArgs`,
+  `ChartreadArgs`, `ColprofArgs`, `ApplycalArgs`, `IccgamutArgs`,
+  `ProfcheckArgs`, `LpArgs`, `SpotReadArgs`, …). UI must not concatenate flags.
+- **Atomic artefacts.** Writes go to `*.tmp` then `replaceItemAt`. `applycal`
+  must not replace the input profile on cancel or non-zero exit.
+- **Concurrency.** View models are `@MainActor`. No blocking I/O on the main
+  actor. Swift 5.7 / macOS 12: `ObservableObject`, not Observation
+  `@Observable`.
+- **Print.** Unmanaged `lp` with ColorSync suppression
+  (`AP_ColorMatchingMode` / `AP.ColorMatchingMode`). Captured `NSPrintPanel`
+  options win over derived CUPS keys. Never `lp -o raw`.
+- **SwiftUI ViewBuilder.** Xcode 14.2 / Swift 5.7 still has the ten-child
+  limit. Split large `VStack`/`Group` trees (#146).
 
 ## Tests
 
 ```bash
-# full suite (host arch)
+# full suite (host arch) — same as CI
 xcodebuild test -scheme ICCery \
   -destination 'platform=macOS' \
   ARCHS="$(uname -m)"
 
-# to compile-check both slices instead:
+# fat compile-check (not the default test path):
 #   ARCHS='arm64 x86_64' ONLY_ACTIVE_ARCH=NO
 
 # examples
@@ -143,9 +206,24 @@ xcodebuild test -scheme ICCery -destination 'platform=macOS' \
   -only-testing:ICCeryUITests/Milestone5UITests
 ```
 
-UI tests need an unlocked console (`IOConsoleLocked=false`). Mock Argyll / CUPS fixtures live under the test bundles; they must not be treated as proof that a real `.gam` / `.icc` was extracted.
+CI (`.gitea/workflows/macos.yml` on Gitea, `.github/workflows/macos.yml` on
+GitHub) runs `build-and-test` then `package` on
+`develop` and on `v*` tags. Tags whose name contains `prerelease` skip the
+test job and still package. `pull_request` is wired for **`develop` only**.
+The GitHub file is the same pipeline on `macos-14` (github.com retired
+`macos-12`), `actions/upload-artifact@v4`, and `gh release upload` for tag
+DMGs.
 
-Hardware gates (real instrument, real printer, Gatekeeper-open `.dmg`) are manual and block release, not compile.
+UI tests need an unlocked console (`IOConsoleLocked=false`). Mock Argyll /
+CUPS fixtures live under the test bundles; they must not be treated as proof
+that a real `.gam` / `.icc` was extracted.
+
+Hardware gates (real instrument, real printer, Gatekeeper-open `.dmg`) are
+manual and block release, not compile.
+
+`ArgyllRunnerPrinttargTests.testSuccess` can flake if streaming stdout is
+dropped on a fast mock exit; that is a `ProcessManager` drain race, not a
+missing fixture.
 
 ## Instruments
 
@@ -156,11 +234,18 @@ Detected via bundled `instlist`:
 - SpyderPrint (`p3`)
 - SpectroScan (`SS`)
 - DTP20 / 22 / 41 / 51
-- XY tables (SpectroScan, i1iO) when the `instlist` name matches `/spectro\s?scan|i1io/i`
+- XY tables (SpectroScan, i1iO) when the `instlist` name matches
+  `/spectro\s?scan|i1io/i`
 
 ## Docs
 
-Normative spec is [`docs/`](docs/README.md). Implementation order:
+| Where | Audience |
+|---|---|
+| [Wiki](https://git.i3omb.com/gronod/iccery-v2-mac/wiki) | End users — screens, workflow, troubleshooting |
+| [`docs/`](docs/README.md) | Functional spec (normative for implementers) |
+| [`AGENTS.md`](AGENTS.md), [`BUILD-PLAN.md`](BUILD-PLAN.md) | Agent / branch rules |
+
+Implementation order in `docs/`:
 
 | Doc | Topic |
 |---|---|
@@ -168,29 +253,40 @@ Normative spec is [`docs/`](docs/README.md). Implementation order:
 | [`docs/03-ipc-and-process-manager.md`](docs/03-ipc-and-process-manager.md) | Spawn / stdin / kill |
 | [`docs/04-argyll-binaries.md`](docs/04-argyll-binaries.md) | CLI argv |
 | [`docs/06-wizard-and-artefacts.md`](docs/06-wizard-and-artefacts.md) | Gating |
+| [`docs/23-assets.md`](docs/23-assets.md) | Icons, DMG chrome |
 | [`docs/24-issues-invariants.md`](docs/24-issues-invariants.md) | Bugs that must not return |
 | [`docs/26-v2-mac-ticket-plan.md`](docs/26-v2-mac-ticket-plan.md) | Gitea tickets |
 | [`docs/PREUAT.md`](docs/PREUAT.md) | Pre-UAT tester kit |
 
-Agent / branch rules: [`AGENTS.md`](AGENTS.md), [`BUILD-PLAN.md`](BUILD-PLAN.md).
-
 ## Git
 
 ```
-develop
+develop          # integration; PRs land here unless a milestone branch is announced
-  └── milestone/m10-studio   # M10 integration branch
+main             # protected release line (PR from develop)
-        └── feat/<issue>-<slug>    # one issue per branch
+feat/<issue>-<slug>
+fix/<issue>-<slug>
 ```
 
-Feature PRs target the current milestone branch, not `develop`. The milestone branch merges to `develop` when its issues are green. Completion PRs for issues #146–#149 target `milestone/m10-studio`; `milestone/m10-studio` merges into `develop` once all milestone gates pass. Do not open umbrella "bugfix" branches that mix tickets.
+Open feature/fix PRs against **`develop`**. A `milestone/m…` integration
+branch is used only while that milestone is assembling; `milestone/m10-studio`
+has been merged and deleted. Do not open umbrella “bugfix” branches that mix
+tickets.
+
+`main` is push-protected and requires status check
+`macOS CI / build-and-test (push)`. Protected **file** patterns on `main`
+block PR merges that touch matching paths — do not set that field to `*`.
 
 ## Licence
 
-GUI source: © 2026 Gordon Bolton — see [`LICENCE.md`](LICENCE.md). Viewing and personal evaluation only unless a separate grant says otherwise.
+GUI source: © 2026 Gordon Bolton — see [`LICENCE.md`](LICENCE.md). Viewing
+and personal evaluation only unless a separate grant says otherwise.
 
-ArgyllCMS binaries fetched into `Vendor/Argyll/` are **AGPLv3**. They stay subprocess-isolated (stdin / stdout / stderr only). Linking them, or spawning via `$PATH`, is a licence break.
+ArgyllCMS binaries fetched into `Vendor/Argyll/` are **AGPLv3**. They stay
+subprocess-isolated (stdin / stdout / stderr only). Linking them, or spawning
+via `$PATH`, is a licence break.
 
 ## Related
 
+- [User wiki](https://git.i3omb.com/gronod/iccery-v2-mac/wiki)
 - [gronod/argyllcms](https://git.i3omb.com/gronod/argyllcms) — Argyll 3.5.0 fork (`-u` JSON, `instlist`)
 - [gronod/ICCery](https://git.i3omb.com/gronod/ICCery) — v1 Tauri application (spec source, not this tree)

Sources/ICCery/ICCeryApp.swift

@@ -56,10 +56,41 @@ final class AppDelegate: NSObject, NSApplicationDelegate {
     }
 
     /// docs/21 §Shell: 1280×800 content, min 1100×700, centred.
+    /// GitHub-hosted Macs (and any display smaller than 1280×800) must
+    /// not get a window that hangs off-screen — XCTest then reports
+    /// sidebar controls at negative x as not hittable (run 34864198118).
     private func configureMainWindow(_ window: NSWindow) {
-        window.setContentSize(NSSize(width: 1280, height: 800))
+        let desired = NSSize(width: 1280, height: 800)
-        window.contentMinSize = NSSize(width: 1100, height: 700)
+        let minimum = NSSize(width: 1100, height: 700)
+        let visible = (window.screen ?? NSScreen.main)?.visibleFrame
+            ?? NSRect(origin: .zero, size: desired)
+
+        window.contentMinSize = NSSize(
+            width: min(minimum.width, visible.width),
+            height: min(minimum.height, visible.height)
+        )
+        window.setContentSize(NSSize(
+            width: min(desired.width, visible.width),
+            height: min(desired.height, max(minimum.height, visible.height - 40))
+        ))
         window.center()
+
+        var frame = window.frame
+        if frame.width > visible.width {
+            frame.size.width = visible.width
+        }
+        if frame.height > visible.height {
+            frame.size.height = visible.height
+        }
+        frame.origin.x = min(
+            max(frame.origin.x, visible.minX),
+            visible.maxX - frame.width
+        )
+        frame.origin.y = min(
+            max(frame.origin.y, visible.minY),
+            visible.maxY - frame.height
+        )
+        window.setFrame(frame, display: true)
     }
 
     /// Dock-click reopen: let the WindowGroup re-show or recreate the

Sources/ICCery/MediaLibraryDialogs.swift

@@ -220,6 +220,15 @@ struct ManageMediaDialog: View {
             .accessibilityIdentifier("mediaLibraryList")
             .frame(minHeight: 260)
 
+            if let notice = media.manageApplyNotice {
+                Text(notice)
+                    .font(.callout)
+                    .foregroundStyle(.orange)
+                    .fixedSize(horizontal: false, vertical: true)
+                    .accessibilityIdentifier("manageMediaNotice")
+                    .accessibilityValue(notice)
+            }
+
             HStack {
                 Button("Apply selected") {
                     if let id = selection,

Sources/ICCery/MediaLibraryViewModel.swift

@@ -41,6 +41,9 @@ final class MediaLibraryViewModel: ObservableObject {
     @Published var saveMediaApplyCal = false
     /// Inline caption inside the capture sheet (no a11y id — roster complete).
     @Published var saveMediaError: String?
+    /// Last failed Apply while Manage is open. The window banner sits
+    /// behind the sheet on Monterey, so the dialog shows this too (#170).
+    @Published var manageApplyNotice: String?
 
     /// Pure flow flag — the manage sheet's "Capture current…" asks the
     /// sheet's `onDismiss` to open the capture sheet, avoiding a
@@ -120,24 +123,21 @@ final class MediaLibraryViewModel: ObservableObject {
     /// with warning; the refusal is permanent so re-clicking can't help).
     @discardableResult
     func apply(_ recipe: MediaRecipe) async -> Bool {
+        manageApplyNotice = nil
         guard let r = try? recipe.validated() else {
-            workflow.wizard.showNotice(
+            return failApply("Media recipe is invalid — not applied.", kind: .error)
-                "Media recipe is invalid — not applied.", kind: .error)
-            return false
         }
         guard let preset = environment.presetStore.all()
             .first(where: { $0.id == r.presetID })
         else {
-            workflow.wizard.showNotice(
+            return failApply(
                 "Preset \(r.presetID) no longer exists — recipe not applied.",
                 kind: .error)
-            return false
         }
         guard preset.colourSpace.lowercased() == r.colourSpace.lowercased() else {
-            workflow.wizard.showNotice(
+            return failApply(
                 "Recipe colour space does not match its preset — not applied.",
                 kind: .error)
-            return false
         }
 
         // Existing #82 mapping: presetSelect jumps, Stage 1/2/4 fields.
@@ -145,8 +145,6 @@ final class MediaLibraryViewModel: ObservableObject {
         // Literal per issue: displayName, not the queue id.
         workflow.wizard.printerName = r.printerDisplayName
 
-        var succeeded = true
-
         // Queue: enumerate fresh via the session's serialized path —
         // listPrinters uses fixed process ids, so an overlapping
         // enumeration would throw duplicateID. An empty result is a
@@ -156,16 +154,14 @@ final class MediaLibraryViewModel: ObservableObject {
                 workflow.print.selectedPrinter = r.printerID
                 await workflow.print.reloadSelectedCapabilities()
             } else {
-                workflow.wizard.showNotice(
+                return failApply(
                     "Printer \(r.printerDisplayName) is not installed.",
                     kind: .warning)
-                succeeded = false
             }
         } else {
-            workflow.wizard.showNotice(
+            return failApply(
                 "Could not enumerate printers — queue left unchanged.",
                 kind: .warning)
-            succeeded = false
         }
 
         // Calibration — the recipe is authoritative and runs after
@@ -195,10 +191,8 @@ final class MediaLibraryViewModel: ObservableObject {
             guard FileManager.default.fileExists(atPath: calPath) else {
                 workflow.profile.applyCalibration = false
                 workflow.profile.calibrationFile = calPath
-                workflow.wizard.showNotice(
+                return failApply(
                     "Calibration file is missing: \(calPath)", kind: .error)
-                refreshStaleness()
-                return false
             }
             do {
                 let staleDays = environment.settingsStore.load().calibrationStaleDays
@@ -215,23 +209,26 @@ final class MediaLibraryViewModel: ObservableObject {
                 }
             } catch {
                 workflow.profile.applyCalibration = false
-                workflow.wizard.showNotice(
+                return failApply(
                     "Could not load calibration: \(error.localizedDescription)",
                     kind: .error)
-                refreshStaleness()
-                return false
             }
         } else {
             workflow.profile.applyCalibration = false
             workflow.profile.calibrationFile = calPath
         }
 
-        if succeeded {
+        selectedRecipeID = r.id
-            selectedRecipeID = r.id
+        workflow.wizard.showNotice("Applied \(r.name)")
-            workflow.wizard.showNotice("Applied \(r.name)")
-        }
         refreshStaleness()
-        return succeeded
+        return true
+    }
+
+    private func failApply(_ text: String, kind: Notice.Kind) -> Bool {
+        manageApplyNotice = text
+        workflow.wizard.showNotice(text, kind: kind)
+        refreshStaleness()
+        return false
     }
 
     // MARK: - Capture

Tests/ICCeryUITests/Milestone10MediaLibraryUITests.swift

@@ -148,7 +148,9 @@ final class Milestone10MediaLibraryUITests: XCTestCase {
         XCTAssertTrue(apply.waitForExistence(timeout: 10))
         apply.click()
 
-        let notice = waitFor("noticeText")
+        // The window banner (`noticeText`) sits behind this sheet on
+        // Monterey (#170). Assert the in-sheet copy instead.
+        let notice = waitFor("manageMediaNotice", timeout: 15)
         let text = (notice.value as? String) ?? notice.label
         XCTAssertTrue(
             text.contains("is not installed"),

Tests/ICCeryUITests/Milestone4UITests.swift

@@ -98,23 +98,9 @@ final class Milestone4UITests: XCTestCase {
         app.buttons["btnDetectInstruments"].click()
         _ = waitFor("chartreadInstrumentSelect", timeout: 20)
 
-        // Keep Auto (port 1) and start the session.
+        // Wait until Start is enabled before clicking. Existence-only
-        XCTAssertTrue(app.buttons["btnStartRead"].waitForExistence(timeout: 5))
+        // clicks are no-ops on the disabled control (runs 35251, 35293).
-        app.buttons["btnStartRead"].click()
+        driveOnePass(startButton: "btnStartRead")
-
-        // Calibrate.
-        let calibrate = element("btnCalibrate")
-        if !calibrate.waitForExistence(timeout: 25) {
-            let error = element("chartreadLastError").label
-            let value = element("chartreadLastError").value as? String ?? "<nil>"
-            XCTFail("No calibrate button. lastError.label='\(error)' value='\(value)'")
-        }
-        app.buttons["btnCalibrate"].click()
-
-        // Trigger each strip until all are read → Done & Save appears.
-        driveStripsUntilDone()
-        XCTAssertTrue(element("btnDoneRead").exists)
-        app.buttons["btnDoneRead"].firstMatch.click()
 
         // Averaging panel appears with one pass snapshot.
         _ = waitFor("chartreadAveragingPanel", timeout: 20)

docs/23-assets.md

@@ -25,7 +25,7 @@ Cone-only mark for window/taskbar. Raster set:
 
 | File | Use |
 |------|-----|
-| `icons/dmg-background.png` (+ `@2x`, `.svg`) | macOS DMG window (ice cream / wordmark scene). Headless `dmgbuild` after #189 |
+| `Resources/dmg-background.png` (+ `@2x`; source `brand/dmg-background.svg`) | macOS DMG window. `scripts/package-release.sh` builds a HiDPI TIFF and passes it to `dmgbuild==1.6.7` from `build/.venv-dmgbuild` (created by `INSTALL_DMGBUILD=1 scripts/ensure-host-tools.sh`). Monterey Python 3.9 needs `PIP_IGNORE_REQUIRES_PYTHON=1` or pip will keep 1.6.5. Missing art is a hard fail (#95, #189). |
 | `icons/wix-banner.bmp`, `wix-dialog.bmp` | MSI |
 | `icons/nsis-header.bmp`, `nsis-sidebar.bmp` | NSIS |
 

project.yml

@@ -21,6 +21,8 @@ targets:
           - ICCery.entitlements
           - ICCery.Debug.entitlements
           - Argyll
+          - dmg-background.png
+          - dmg-background@2x.png
       - path: Resources/Argyll
         type: folder
     dependencies:

scripts/dmgbuild-settings.py

@@ -1,10 +1,10 @@
 #!/usr/bin/env python3
 # scripts/dmgbuild-settings.py
 #
-# dmgbuild settings for ICCery. Set DMG_APP, DMG_FILENAME and DMG_VOLUME_NAME
+# dmgbuild settings for ICCery. scripts/package-release.sh exports
-# in the environment, or accept the defaults. Background art can be supplied
+# DMG_APP, DMG_FILENAME, DMG_VOLUME_NAME, and DMG_BACKGROUND (a
-# later by placing a PNG at Resources/dmg-background.png and setting
+# HiDPI TIFF). A missing background is a hard error — a grey
-# DMG_BACKGROUND.
+# Finder window is not an acceptable release artefact (#95).
 
 import os
 import sys
@@ -23,15 +23,23 @@ if not app_path or not app_path.endswith('.app') or not os.path.isdir(app_path):
 
 files = [app_path]
 
-# Background art is optional. If the referenced PNG does not exist, fall back
+# Finder on Sonoma+ is picky about PNG-with-alpha window pictures and
-# to a plain window. See docs/23-assets.md for the DMG background spec.
+# about classic Alias Manager blobs. package-release.sh always passes
-background = os.environ.get('DMG_BACKGROUND', 'Resources/dmg-background.png')
+# a flattened HiDPI TIFF as DMG_BACKGROUND. dmgbuild 1.6.7 (bookmark
-if background and not os.path.exists(background):
+# .DS_Store) needs Python >= 3.10, which the Monterey runner does not
-    background = None
+# have; 1.6.5 + TIFF is what CI can ship (#95).
+background = os.environ.get('DMG_BACKGROUND', '')
+if not background or not os.path.isfile(background):
+    sys.stderr.write(
+        'error: DMG_BACKGROUND must point at an existing image '
+        '(got %r)\n' % background)
+    sys.exit(1)
 
 icon = None
 
 # Window size is enough for the app icon and the Applications alias.
+# Bitmap is slightly larger than this rect so title-bar chrome on
+# 14+ does not crop the wordmark.
 window_rect = ((100, 100), (660, 400))
 
 # Use icon view without extra chrome.

scripts/ensure-host-tools.sh

@@ -2,19 +2,79 @@
 # scripts/ensure-host-tools.sh
 #
 # Bootstrap host tools needed by CI on the macOS 12 runner:
-#   - xcodegen: pinned prebuilt release from GitHub (Homebrew's current
+#   - xcodegen: always. Pinned prebuilt release from GitHub (Homebrew's
-#     formula requires Xcode 15.3, which cannot be installed on macOS 12).
+#     current formula requires Xcode 15.3, which cannot be installed on
-#   - dmgbuild: via pip3 (used by scripts/package-release.sh).
+#     macOS 12).
+#   - dmgbuild: only when INSTALL_DMGBUILD=1 or --dmgbuild. Isolated in
+#     build/.venv-dmgbuild so the test job never pip-installs it.
 #
-# Safe to run repeatedly: existing tools are left alone.
+# dmgbuild 1.6.6+, ds_store 1.3.2+ and mac_alias 2.2.3 declare
+# Requires-Python >= 3.10. The wheels are py3-none-any and run on the
+# runner's 3.9; PIP_IGNORE_REQUIRES_PYTHON is required or pip will only
+# offer 1.6.5 and keep a cached venv on that version (#95).
+# pip itself is capped at <26.1: 26.1+ needs Python 3.10.
+#
+# Safe to run repeatedly: existing tools are left alone unless the
+# dmgbuild pin is not met.
 
 set -eu
 
+ROOT="$(CDPATH='' cd -- "$(dirname -- "$0")/.." && pwd)"
 XCODEGEN_VERSION="2.38.0"
 INSTALL_ROOT="${XCODEGEN_HOME:-$HOME/.local/xcodegen/$XCODEGEN_VERSION}"
+VENV="$ROOT/build/.venv-dmgbuild"
+DMGBUILD_PIN="1.6.7"
 
-echo "==> Ensuring dmgbuild"
+INSTALL_DMGBUILD="${INSTALL_DMGBUILD:-0}"
-python3 -c "import dmgbuild" 2>/dev/null || pip3 install dmgbuild
+for arg in "$@"; do
+    case "$arg" in
+        --dmgbuild) INSTALL_DMGBUILD=1 ;;
+    esac
+done
+
+if [ "$INSTALL_DMGBUILD" = "1" ]; then
+    echo "==> Ensuring dmgbuild==$DMGBUILD_PIN in $VENV"
+    mkdir -p "$ROOT/build"
+    # pip 26.1+ requires Python 3.10 (dataclass slots). A leftover
+    # `pip install --upgrade pip` on this 3.9 venv installed 26.2.1 and
+    # the next pip invocation crashed. Recreate if pip is already dead.
+    if [ -x "$VENV/bin/python" ] \
+        && ! "$VENV/bin/python" -m pip --version >/dev/null 2>&1; then
+        echo "==> venv pip is broken; recreating $VENV"
+        rm -rf "$VENV"
+    fi
+    if [ ! -x "$VENV/bin/python" ]; then
+        python3 -m venv "$VENV"
+    fi
+    # Without this, pip on Python 3.9 hides 1.6.6+ and leaves 1.6.5.
+    PIP_IGNORE_REQUIRES_PYTHON=1
+    export PIP_IGNORE_REQUIRES_PYTHON
+    "$VENV/bin/python" -m pip install --upgrade 'pip>=24.3,<26.1'
+    "$VENV/bin/python" -m pip install --upgrade --force-reinstall \
+        "dmgbuild==$DMGBUILD_PIN" \
+        'ds_store>=1.3.3' \
+        'mac_alias>=2.2.3'
+    "$VENV/bin/python" -c 'from importlib.metadata import version
+print("dmgbuild", version("dmgbuild"))
+print("ds_store", version("ds_store"))
+print("mac_alias", version("mac_alias"))
+parts=[]
+for p in version("dmgbuild").split("."):
+    try:
+        parts.append(int("".join(c for c in p if c.isdigit()) or "0"))
+    except ValueError:
+        parts.append(0)
+parts += [0, 0, 0]
+raise SystemExit(0 if tuple(parts[:3]) >= (1, 6, 7) else 1)
+'
+    if [ -n "${GITHUB_PATH:-}" ]; then
+        echo "$VENV/bin" >> "$GITHUB_PATH"
+    fi
+    PATH="$VENV/bin:$PATH"
+    export PATH
+else
+    echo "==> Skipping dmgbuild (set INSTALL_DMGBUILD=1 for the package job)"
+fi
 
 if command -v xcodegen >/dev/null 2>&1; then
     echo "==> xcodegen already on PATH: $(xcodegen --version)"

scripts/package-release.sh

@@ -103,19 +103,39 @@ EOF
     scripts/verify-sidecar-signatures.sh "$APP"
 fi
 
-echo "==> Installing / locating dmgbuild"
+echo "==> Locating dmgbuild"
+# The package CI job already ran INSTALL_DMGBUILD=1 ensure-host-tools.sh,
+# which created build/.venv-dmgbuild and prepended it to PATH. Local
+# runs bootstrap the same venv if dmgbuild is missing.
+VENV="$ROOT/build/.venv-dmgbuild"
 if ! command -v dmgbuild >/dev/null 2>&1; then
-    VENV="$ROOT/build/.venv-dmgbuild"
+    if [ ! -x "$VENV/bin/dmgbuild" ]; then
-    if [ ! -d "$VENV/bin" ]; then
+        INSTALL_DMGBUILD=1 "$ROOT/scripts/ensure-host-tools.sh" --dmgbuild
-        python3 -m venv "$VENV"
-        "$VENV/bin/pip" install --upgrade pip
-        "$VENV/bin/pip" install dmgbuild
     fi
     PATH="$VENV/bin:$PATH"
     export PATH
 fi
 if ! command -v dmgbuild >/dev/null 2>&1; then
-    echo "error: dmgbuild not available. Try 'python3 -m venv .venv && pip install dmgbuild'" >&2
+    echo "error: dmgbuild not on PATH; run INSTALL_DMGBUILD=1 scripts/ensure-host-tools.sh" >&2
+    exit 1
+fi
+echo "dmgbuild $(command -v dmgbuild)"
+if [ -x "$VENV/bin/python" ]; then
+    "$VENV/bin/python" -c 'from importlib.metadata import version; print("dmgbuild", version("dmgbuild"))'
+fi
+
+PNG1X="$ROOT/Resources/dmg-background.png"
+PNG2X="$ROOT/Resources/dmg-background@2x.png"
+if [ ! -f "$PNG1X" ] || [ ! -f "$PNG2X" ]; then
+    echo "error: missing $PNG1X or $PNG2X" >&2
+    exit 1
+fi
+mkdir -p "$ROOT/build"
+DMG_BACKGROUND="$ROOT/build/dmg-background.tiff"
+echo "==> Building HiDPI DMG background TIFF"
+tiffutil -cathidpicheck "$PNG1X" "$PNG2X" -out "$DMG_BACKGROUND"
+if [ ! -f "$DMG_BACKGROUND" ]; then
+    echo "error: tiffutil did not write $DMG_BACKGROUND" >&2
     exit 1
 fi
 
@@ -128,6 +148,7 @@ VOLUME_NAME="ICCery ${VERSION}"
 DMG_APP="$APP" \
 DMG_FILENAME="$DMG" \
 DMG_VOLUME_NAME="$VOLUME_NAME" \
+DMG_BACKGROUND="$DMG_BACKGROUND" \
 dmgbuild -s scripts/dmgbuild-settings.py "$VOLUME_NAME" "$DMG"
 
 echo "DMG: $PWD/$DMG"