ci: pin Xcode 26.6, run the consumer checks and an iOS build

.github/workflows/ci.yml

@@ -1,7 +1,8 @@
-# CuboKit CI: the test run (tools/test.sh = `swift test -c release`) and, on a tag, the CHANGELOG version check.
+# CuboKit CI: the test run (tools/test.sh = `swift test -c release`) on every pull request; after merge the consumer check,
+# the README consumer and an iOS Simulator build; on a tag, the CHANGELOG version check.
 #
-# Actions must be enabled on the repository. The package needs macOS 15 or later and a Swift 6.2 or later toolchain
-# (Package.swift: `.macOS(.v15)`, tools 6.2); `macos-latest` with its newest Xcode carries both.
+# The package needs macOS 15 / iOS 18 or later and a Swift 6.2 or later toolchain (Package.swift: tools 6.2); the
+# macos-26 image with Xcode 26.6, pinned below, carries both.
 # No real data in CI: RealDataTests skip by name when ~/Library/Caches/CuboKit/real-data is absent, so tools/test.sh is
 # green without it. No libhdf5 and no References/ (CuboKit has no package dependencies).
 # Never `swift build --build-tests -c release` (fails on this toolchain's Swift Build backend); tools/test.sh is the gate.
@@ -18,20 +19,38 @@ concurrency:
   group: ci-${{ github.ref }}
   cancel-in-progress: true
 
+env:
+  # Pinned like the apps: the macos-26 image's Xcode 26.6 (Swift 6.3, macOS 26 SDK). Bump on purpose.
+  DEVELOPER_DIR: /Applications/Xcode_26.6.app/Contents/Developer
+
 jobs:
   test:
-    runs-on: macos-latest
+    runs-on: macos-26
     timeout-minutes: 90
     steps:
       - uses: actions/checkout@v7
-      - name: Select the newest Xcode
+      - name: Toolchain on record
         run: |
-          xcode=$(ls -d /Applications/Xcode*.app | sort -V | tail -1)
-          sudo xcode-select -s "$xcode"
+          xcode-select -p
           swift --version
       - name: Gate (tools/test.sh, release)
         run: tools/test.sh
 
+  post-merge:
+    name: Consumer checks and iOS build (after merge)
+    # Not on pull requests: the free plan's macOS runners are scarce, so the extra builds run on main, tags and by hand.
+    if: github.event_name != 'pull_request'
+    runs-on: macos-26
+    timeout-minutes: 90
+    steps:
+      - uses: actions/checkout@v7
+      - name: Consumer check (a separate package, the public API only)
+        run: tools/consumer-check/run.sh
+      - name: README consumer (a separate package compiling exactly the README's program, output checked)
+        run: tools/readme-consumer/run.sh
+      - name: Build the libraries for iOS (Simulator, not run)
+        run: xcodebuild -scheme CuboKit-Package -destination 'generic/platform=iOS Simulator' -quiet build
+
   version:
     name: CHANGELOG version matches the tag
     runs-on: ubuntu-latest
@@ -59,7 +78,7 @@ jobs:
     name: Lint (shared SwiftLint and SwiftFormat config)
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
       - name: SwiftLint
         run: docker run --rm -v "$PWD:/work" -w /work --entrypoint swiftlint ghcr.io/realm/swiftlint:0.65.1 lint --strict --quiet
       - name: SwiftFormat

.github/workflows/docs.yml

@@ -23,16 +23,19 @@ concurrency:
   group: docs-${{ github.ref }}
   cancel-in-progress: true
 
+env:
+  # Pinned like the apps: the macos-26 image's Xcode 26.6 (Swift 6.3, macOS 26 SDK). Bump on purpose.
+  DEVELOPER_DIR: /Applications/Xcode_26.6.app/Contents/Developer
+
 jobs:
   build:
-    runs-on: macos-latest
+    runs-on: macos-26
     timeout-minutes: 60
     steps:
       - uses: actions/checkout@v7
-      - name: Select the newest Xcode
+      - name: Toolchain on record
         run: |
-          xcode=$(ls -d /Applications/Xcode*.app | sort -V | tail -1)
-          sudo xcode-select -s "$xcode"
+          xcode-select -p
           xcodebuild -version
       - name: Build the site
         run: tools/build-docs.sh .docs-site /CuboKit

Tests/CuboVirtualTests/TruthTests.swift

@@ -117,7 +117,7 @@ import CuboVirtual
         for (row, column) in [(1, 5), (3, 2), (4, 0), (0, 6), (2, 4)] {
             for path in paths {
                 let image = try await VirtualImaging.image(of: source, geometry: .point(row: row, column: column), path: path)
-                #expect(image.values == (0..<6).map { Double($0 * 10000 + row * 100 + column) }, "(\(row), \(column)) \(path)")
+                #expect(image.values == (0..<6).map { (i: Int) -> Double in Double(i * 10000 + row * 100 + column) }, "(\(row), \(column)) \(path)")
             }
         }
     }

tools/consumer-check/Sources/consumer-check/main.swift

@@ -475,7 +475,7 @@ check("CuboVirtualError.invalidInput", CuboVirtualError.invalidInput("x") == .in
 // HotPixelFilter.Replacer: the reusable in-place replacement plan (equals the one-frame `replacing`).
 do {
     let hpMask = (0..<20).map { $0 % 7 == 3 }
-    let hpFrame = (0..<20).map { Float(($0 * 37) % 11) + (($0 == 3) ? 50 : 0) }
+    let hpFrame: [Float] = (0..<20).map { (i: Int) -> Float in Float((i * 37) % 11) + (i == 3 ? 50 : 0) }
     var hpPlanned = hpFrame
     let replacer = try HotPixelFilter.Replacer(rows: 4, columns: 5, mask: hpMask)
     replacer.apply(to: &hpPlanned)
@@ -659,7 +659,9 @@ do {
     let probe = try PtychographyArray(rows: d, columns: d, real: probeRe, imaginary: [Double](repeating: 0, count: d * d))
     let object = try PtychographyArray(rows: 24, columns: 24, real: [Double](repeating: 1, count: 576), imaginary: [Double](repeating: 0, count: 576))
     let amps = [Double](repeating: 1, count: count * d * d)
-    let positions = (0..<count).map { PtychographyPosition(row: Double(8 + 3 * $0), column: Double(8 + 2 * $0)) }
+    let positions: [PtychographyPosition] = (0..<count).map { (i: Int) -> PtychographyPosition in
+        PtychographyPosition(row: Double(8 + 3 * i), column: Double(8 + 2 * i))
+    }
     nonisolated(unsafe) var ptychoProgress: [Int] = []
     let single = try SingleslicePtychography.reconstruct(amplitudes: amps, positions: positions, object: object, probe: probe, iterations: 2,
                                                          precision: .single, progress: { done, _ in ptychoProgress.append(done) })