Wizard state machine & artefact gating (#4)

- WizardState: Codable persisted fields — currentStage, basename, cwd,
  printerName, sessionMode (profile|calibration), profileBasename;
  WizardStateStore writes wizard_state.json atomically
- WizardGating: pure gating — 1 always; 2 on .ti1; 3 on .ti1+.ti2; 4 on
  .ti3 only (never .ti2 — #109/#110); 5 on .ti3+profile (#69). Forward
  gated, backward always; Stage 0 a side-trip
- WizardViewModel: setTarget sanitises basename (#60) and resolves cwd
  (#59); locked forward nav shows a warning banner; windowDidBecomeKey
  re-probes and drops back to deepest unlocked when files vanish (#151)
- RootView: NSWindow.didBecomeKeyNotification -> revalidate
- Sidebar stepper enabled state now driven by artefact gating
- 11 new tests incl. gating matrix + persistence; 71/71 green

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

Packages/ICCeryCore/Sources/ICCeryCore/Argyll/BinaryResolver.swift

@@ -0,0 +1,100 @@
+import Foundation
+
+/// Resolves Argyll sidecar binaries (docs/04 §0.1 `resolve_binary`).
+///
+/// Order:
+/// 1. Settings `argyll_binary_dir` override — only if `<dir>/<name>`
+///    exists there.
+/// 2. Bundled `<bundle>/Resources/Argyll/<platform>/<name>`.
+///    On macOS, `macos-universal` wins whenever it contains the `instlist`
+///    marker; otherwise `macos-arm64` / `macos-x86_64` by host arch.
+/// 3. If nothing exists the *constructed* bundled path is still returned
+///    — a missing binary surfaces later as `process:error` on spawn,
+///    matching v1 semantics.
+public struct BinaryResolver: Sendable {
+
+    /// Root that contains the platform dirs — `Bundle.resource/Argyll` in
+    /// the app, a fixture dir in tests.
+    public let bundledRoot: URL
+    /// `settings.argyll_binary_dir`, already expanded to a URL.
+    public let overrideDir: URL?
+    /// Host architecture directory names, universal preferred.
+    public let archDirs: [String]
+
+    public init(
+        bundledRoot: URL = AppPaths.bundledArgyllDir,
+        overrideDir: URL? = nil,
+        archDirs: [String]? = nil
+    ) {
+        self.bundledRoot = bundledRoot
+        self.overrideDir = overrideDir
+        #if arch(arm64)
+        let fallback = ["macos-arm64", "macos-aarch64"]
+        #else
+        let fallback = ["macos-x86_64"]
+        #endif
+        self.archDirs = archDirs ?? ["macos-universal"] + fallback
+    }
+
+    /// Marker used to decide whether `macos-universal` is usable.
+    public static let markerBinary = "instlist"
+
+    /// Resolves a tool name to an absolute URL (never throws — see type
+    /// docs). `name` is the bare tool name, e.g. `"targen"`.
+    public func resolve(_ name: String) -> URL {
+        let fm = FileManager.default
+
+        if let dir = overrideDir {
+            let candidate = dir.appendingPathComponent(name)
+            if fm.fileExists(atPath: candidate.path) {
+                return candidate
+            }
+        }
+
+        return bundledRoot
+            .appendingPathComponent(platformDir(), isDirectory: true)
+            .appendingPathComponent(name, isDirectory: false)
+    }
+
+    /// The bundled platform directory that resolution will use.
+    public func platformDir() -> String {
+        let fm = FileManager.default
+        let universal = bundledRoot.appendingPathComponent("macos-universal")
+        if fm.fileExists(
+            atPath: universal.appendingPathComponent(Self.markerBinary).path
+        ) {
+            return "macos-universal"
+        }
+        for dir in archDirs where dir != "macos-universal" {
+            if fm.fileExists(
+                atPath: bundledRoot
+                    .appendingPathComponent(dir)
+                    .appendingPathComponent(Self.markerBinary).path
+            ) {
+                return dir
+            }
+        }
+        // Nothing present — still return the preferred dir so the error
+        // message points at where the user should drop binaries.
+        return archDirs.first ?? "macos-universal"
+    }
+
+    /// Bundled mock tool (tracked in git under `Resources/Argyll/mocks/`).
+    public func mock(_ name: String) -> URL {
+        bundledRoot
+            .appendingPathComponent("mocks", isDirectory: true)
+            .appendingPathComponent("\(name).mock", isDirectory: false)
+    }
+
+    /// Bundled reference gamut (`Resources/Argyll/reference_gamuts/`).
+    public func referenceGamut(_ name: String) -> URL {
+        bundledRoot
+            .appendingPathComponent("reference_gamuts", isDirectory: true)
+            .appendingPathComponent(name, isDirectory: false)
+    }
+
+    /// Whether the resolved path exists and is executable.
+    public func exists(_ url: URL) -> Bool {
+        FileManager.default.isExecutableFile(atPath: url.path)
+    }
+}

Packages/ICCeryCore/Sources/ICCeryCore/Files/ArtefactFiles.swift

@@ -0,0 +1,28 @@
+import Foundation
+
+/// Small host-side file helpers (issue #6).
+public enum ArtefactFiles {
+
+    /// `get_default_working_dir` — `resolveSafeCwd(nil)`.
+    public static func defaultWorkingDirectory() -> URL {
+        PathSecurity.resolveSafeCwd(nil)
+    }
+
+    /// `read_file_base64` — for **text artefacts** the UI needs verbatim
+    /// (ti1/ti2 previews, CGATS datasets, logs). Binary payloads (TIFF)
+    /// go through `TiffPreview` instead.
+    public static func readBase64(_ url: URL) throws -> String {
+        try Data(contentsOf: url).base64EncodedString()
+    }
+
+    /// `get_app_info` — version + build for the About dialog.
+    public static func appInfo(
+        bundle: Bundle = .main
+    ) -> (version: String, build: String) {
+        let info = bundle.infoDictionary ?? [:]
+        return (
+            info["CFBundleShortVersionString"] as? String ?? "0.0.0",
+            info["CFBundleVersion"] as? String ?? "0"
+        )
+    }
+}

Packages/ICCeryCore/Sources/ICCeryCore/Files/ArtefactProbe.swift

@@ -0,0 +1,112 @@
+import Foundation
+
+/// Result of `verify_stage_artefacts(cwd, basename)` (docs/06).
+public struct StageArtefacts: Sendable, Equatable {
+    /// `<basename>.ti1` exists (Stage 1 done → unlocks Stage 2).
+    public var stage1Complete = false
+    /// `<basename>.ti2` exists (Stage 2 done → with ti1, unlocks Stage 3).
+    public var stage2Complete = false
+    /// `<basename>.ti3` exists (Stage 3 done → unlocks Stage 4).
+    public var stage3Complete = false
+    /// `.icc`/`.icm` exists (Stage 4 done → with ti3, unlocks Stage 5).
+    public var stage4Complete = false
+    /// Absolute path of the profile file when present.
+    public var profilePath: URL?
+
+    public init(
+        stage1Complete: Bool = false,
+        stage2Complete: Bool = false,
+        stage3Complete: Bool = false,
+        stage4Complete: Bool = false,
+        profilePath: URL? = nil
+    ) {
+        self.stage1Complete = stage1Complete
+        self.stage2Complete = stage2Complete
+        self.stage3Complete = stage3Complete
+        self.stage4Complete = stage4Complete
+        self.profilePath = profilePath
+    }
+}
+
+/// Filesystem probing for wizard artefacts (docs/02 §Working directory,
+/// docs/06 §Stages). All artefacts live next to each other in `cwd`.
+public enum ArtefactProbe {
+
+    /// `verify_stage_artefacts` — the gating truth source.
+    public static func verify(
+        basename: String,
+        cwd: URL,
+        fileManager: FileManager = .default
+    ) -> StageArtefacts {
+        var out = StageArtefacts()
+        out.stage1Complete = exists(artefact(basename, "ti1", cwd), fm: fileManager)
+        out.stage2Complete = exists(artefact(basename, "ti2", cwd), fm: fileManager)
+        out.stage3Complete = exists(artefact(basename, "ti3", cwd), fm: fileManager)
+        if let profile = resolveProfile(basename: basename, cwd: cwd, fileManager: fileManager) {
+            out.stage4Complete = true
+            out.profilePath = profile
+        }
+        return out
+    }
+
+    /// `<cwd>/<basename>.<ext>` — the canonical artefact URL.
+    public static func artefact(_ basename: String, _ ext: String, _ cwd: URL) -> URL {
+        cwd.appendingPathComponent("\(basename).\(ext)", isDirectory: false)
+    }
+
+    /// Profile extension resolution (#69): existing `.icm` wins over
+    /// `.icc`; when neither exists the macOS default is `.icc`.
+    /// (`profcheck`/`iccgamut` swap extension when the requested path is
+    /// missing.)
+    public static func resolveProfile(
+        basename: String,
+        cwd: URL,
+        fileManager: FileManager = .default
+    ) -> URL? {
+        let icm = artefact(basename, "icm", cwd)
+        if exists(icm, fm: fileManager) { return icm }
+        let icc = artefact(basename, "icc", cwd)
+        if exists(icc, fm: fileManager) { return icc }
+        return nil
+    }
+
+    /// Default extension for a *new* profile on macOS (#69).
+    public static let defaultProfileExtension = "icc"
+
+    /// Every artefact path for a basename: `.ti1 .ti2 .tif .N.tif
+    /// .ti3 _passN.ti3 .icc .icm .gam` plus the `CAL_<basename>` namespace.
+    /// Multi-page TIFFs match `<basename>.tif`, `<basename>.1.tif` … and
+    /// `<basename>_NN.tif` (manifest naming).
+    public static func existingArtefacts(
+        basename: String,
+        cwd: URL,
+        fileManager: FileManager = .default
+    ) -> [URL] {
+        guard let entries = try? fileManager.contentsOfDirectory(
+            at: cwd,
+            includingPropertiesForKeys: nil,
+            options: [.skipsHiddenFiles]
+        ) else { return [] }
+
+        let prefixes = [basename + ".", "CAL_" + basename + "."]
+        let suffixes: Set<String> = ["ti1", "ti2", "tif", "ti3", "icc", "icm", "gam", "cal"]
+        let passPrefix = basename + "_pass"
+        let tifStemPrefix = basename + "_"
+        let calPrefix = "CAL_" + basename
+
+        return entries.filter { url in
+            let name = url.lastPathComponent
+            let ext = url.pathExtension.lowercased()
+            guard suffixes.contains(ext) else { return false }
+            if prefixes.contains(where: { name.hasPrefix($0) }) { return true }
+            if name.hasPrefix(passPrefix), ext == "ti3" { return true }
+            if name.hasPrefix(tifStemPrefix), ext == "tif" { return true }
+            if name.hasPrefix(calPrefix) { return true }
+            return false
+        }.sorted { $0.lastPathComponent < $1.lastPathComponent }
+    }
+
+    private static func exists(_ url: URL, fm: FileManager) -> Bool {
+        fm.fileExists(atPath: url.path)
+    }
+}

Packages/ICCeryCore/Sources/ICCeryCore/Files/AtomicFileWriter.swift

@@ -0,0 +1,34 @@
+import Foundation
+
+/// Atomic `.tmp`-then-rename file writes — the convention used by
+/// settings.json, verification_history.json and wizard_state.json
+/// (docs/02 §Persistence, #213).
+public enum AtomicFileWriter {
+
+    /// Writes `data` to `url` atomically: sibling `<name>.tmp`, then a
+    /// rename (which is atomic on APFS/HFS+). Parent dirs are created.
+    public static func write(_ data: Data, to url: URL) throws {
+        let fm = FileManager.default
+        let dir = url.deletingLastPathComponent()
+        try fm.createDirectory(at: dir, withIntermediateDirectories: true)
+
+        let tmp = url.appendingPathExtension("tmp")
+        do {
+            try data.write(to: tmp, options: [])
+            // replaceItemAt handles same-volume atomic swap and removes
+            // the destination cleanly; fall back to remove+move.
+            if fm.fileExists(atPath: url.path) {
+                _ = try fm.replaceItemAt(url, withItemAt: tmp)
+            } else {
+                try fm.moveItem(at: tmp, to: url)
+            }
+        } catch {
+            try? fm.removeItem(at: tmp)
+            throw error
+        }
+    }
+
+    public static func write(_ text: String, to url: URL) throws {
+        try write(Data(text.utf8), to: url)
+    }
+}

Packages/ICCeryCore/Sources/ICCeryCore/Files/PathSecurity.swift

@@ -0,0 +1,54 @@
+import Foundation
+
+/// Basename sanitisation and safe working-directory resolution
+/// (docs/02 §Working directory, docs/06 §Empty cwd).
+public enum PathSecurity {
+
+    public enum Error: Swift.Error, Equatable, Sendable {
+        case invalidBasename(String)
+    }
+
+    /// Basenames must not contain `/`, `\`, or `..` and must be
+    /// non-empty. Never invent a default basename (#60).
+    public static func isValidBasename(_ name: String) -> Bool {
+        guard !name.isEmpty else { return false }
+        return !name.contains("/") && !name.contains("\\") && !name.contains("..")
+    }
+
+    @discardableResult
+    public static func sanitizeBasename(_ name: String) throws -> String {
+        guard isValidBasename(name) else {
+            throw Error.invalidBasename(name)
+        }
+        return name
+    }
+
+    /// `resolve_safe_cwd` (docs/04 §0.2): explicit real directory →
+    /// Documents → Home → app-data. Never returns an empty/nil cwd.
+    public static func resolveSafeCwd(
+        _ explicit: URL?,
+        fileManager: FileManager = .default
+    ) -> URL {
+        if let explicit,
+           fileManager.fileExists(atPath: explicit.path, isDirectory: nil) {
+            return explicit
+        }
+        let candidates: [URL?] = [
+            fileManager.urls(for: .documentDirectory, in: .userDomainMask).first,
+            fileManager.homeDirectoryForCurrentUser,
+            AppPaths.appDataDir,
+        ]
+        for candidate in candidates {
+            guard let url = candidate else { continue }
+            if !fileManager.fileExists(atPath: url.path) {
+                try? fileManager.createDirectory(at: url, withIntermediateDirectories: true)
+            }
+            if fileManager.fileExists(atPath: url.path, isDirectory: nil) {
+                return url
+            }
+        }
+        // Last resort: app-data, created unconditionally.
+        try? fileManager.createDirectory(at: AppPaths.appDataDir, withIntermediateDirectories: true)
+        return AppPaths.appDataDir
+    }
+}

Packages/ICCeryCore/Sources/ICCeryCore/Files/Ti2Header.swift

@@ -0,0 +1,53 @@
+import Foundation
+
+/// Parsed header of a `.ti2` chart-layout file (docs/06 §Resume).
+/// `parse_ti2_header` reads only CGATS keyword lines — the data grid
+/// itself belongs to issue #30.
+public struct Ti2Header: Sendable, Equatable {
+    /// `TARGET_INSTRUMENT` (e.g. `i1`, `i1iO`, `CM`).
+    public var instrument: String?
+    /// `NUMBER_OF_SETS` — the patch count. Note: `NUMBER_OF_FIELDS` is
+    /// the CGATS column count, *not* the patch count.
+    public var patchCount: Int?
+    /// `NUMBER_OF_PAGES`.
+    public var pageCount: Int?
+    /// A sibling `<stem>.ti1` exists next to the parsed file.
+    public var hasSiblingTi1 = false
+
+    public static func parse(
+        _ url: URL,
+        fileManager: FileManager = .default
+    ) -> Ti2Header {
+        var header = Ti2Header()
+        guard let text = try? String(contentsOf: url, encoding: .utf8) else {
+            return header
+        }
+        for rawLine in text.split(whereSeparator: \.isNewline) {
+            let line = rawLine.trimmingCharacters(in: .whitespaces)
+            if line.hasPrefix("BEGIN_DATA_FORMAT") || line.hasPrefix("BEGIN_DATA") {
+                break
+            }
+            // CGATS keyword lines: `KEYWORD "value"` or `KEYWORD value`.
+            guard let space = line.firstIndex(of: " ") else { continue }
+            let key = String(line[..<space])
+            let value = String(line[line.index(after: space)...])
+                .trimmingCharacters(in: .whitespaces)
+                .trimmingCharacters(in: CharacterSet(charactersIn: "\""))
+            switch key {
+            case "TARGET_INSTRUMENT":
+                header.instrument = value
+            case "NUMBER_OF_SETS":
+                header.patchCount = Int(value)
+            case "NUMBER_OF_PAGES":
+                header.pageCount = Int(value)
+            default:
+                continue
+            }
+        }
+        let stem = url.deletingPathExtension()
+        header.hasSiblingTi1 = fileManager.fileExists(
+            atPath: stem.appendingPathExtension("ti1").path
+        )
+        return header
+    }
+}

Packages/ICCeryCore/Sources/ICCeryCore/Files/TiffPreview.swift

@@ -0,0 +1,38 @@
+import Foundation
+import ImageIO
+import UniformTypeIdentifiers
+
+/// TIFF → PNG preview for the Stage 2 gallery (#58): decode on the host
+/// side, cap the long edge at 1200 px, emit PNG. Never hand raw TIFF
+/// bytes to the UI.
+public enum TiffPreview {
+
+    public static let maxEdge: Int = 1200
+
+    /// Returns PNG data for the first page of a TIFF, or `nil` when the
+    /// file cannot be decoded.
+    public static func previewPNG(
+        tiff url: URL,
+        maxEdge: Int = Self.maxEdge
+    ) -> Data? {
+        guard let source = CGImageSourceCreateWithURL(url as CFURL, nil) else {
+            return nil
+        }
+        let options: [CFString: Any] = [
+            kCGImageSourceCreateThumbnailFromImageAlways: true,
+            kCGImageSourceThumbnailMaxPixelSize: maxEdge,
+            kCGImageSourceCreateThumbnailWithTransform: true,
+        ]
+        guard let image = CGImageSourceCreateThumbnailAtIndex(
+            source, 0, options as CFDictionary
+        ) else { return nil }
+
+        let out = NSMutableData()
+        guard let dest = CGImageDestinationCreateWithData(
+            out, UTType.png.identifier as CFString, 1, nil
+        ) else { return nil }
+        CGImageDestinationAddImage(dest, image, nil)
+        guard CGImageDestinationFinalize(dest) else { return nil }
+        return out as Data
+    }
+}

Packages/ICCeryCore/Sources/ICCeryCore/Logging/AppLogger.swift

@@ -15,6 +15,7 @@ public enum LogLevel: String, Codable, Sendable, CaseIterable {
         }
     }
 
+    /// Lower rank = more severe. `shouldLog` keeps `rank <= min`.
     var rank: Int {
         switch self {
         case .error: return 0
@@ -26,16 +27,19 @@ public enum LogLevel: String, Codable, Sendable, CaseIterable {
     }
 }
 
-/// Central logger. For M1 PR2 this writes to `os.Logger` only;
-/// issue #5 adds the rolling file sink and runtime `setLevel`.
+/// Central logger: `os.Logger` + rolling file sink (`LogSink`), level
+/// gated at write time so a settings save takes effect immediately
+/// (#158).
 public struct AppLogger: Sendable {
     public static let shared = AppLogger(category: "app")
 
     private let osLog: Logger
+    private let sink: LogSink
     public let category: String
 
-    public init(category: String) {
+    public init(category: String, sink: LogSink = .shared) {
         self.category = category
+        self.sink = sink
         self.osLog = Logger(
             subsystem: AppPaths.bundleIdentifier,
             category: category
@@ -44,7 +48,10 @@ public struct AppLogger: Sendable {
 
     public func log(_ level: LogLevel, _ message: @autoclosure () -> String) {
         let text = LogSanitizer.sanitize(message())
-        osLog.log(level: level.osType, "\(text, privacy: .public)")
+        if level.rank <= sink.level.rank {
+            osLog.log(level: level.osType, "\(text, privacy: .public)")
+        }
+        sink.write(level: level, category: category, message: text)
     }
 
     public func error(_ message: @autoclosure () -> String) { log(.error, message()) }

Packages/ICCeryCore/Sources/ICCeryCore/Logging/RollingFileLogger.swift

@@ -0,0 +1,127 @@
+import Foundation
+import OSLog
+
+/// Rolling file sink for `AppLogger` — `~/Library/Logs/<bundle>/
+/// iccery.log`, rotated at 5 MiB, keeping 5 historical segments
+/// (`iccery.log.1` … `iccery.log.5`).
+///
+/// The minimum level is **runtime state** (#158): `setLevel` takes
+/// effect immediately — at startup and on every settings save.
+public final class LogSink: @unchecked Sendable {
+
+    public static let shared = LogSink(fileURL: AppPaths.logFile)
+
+    private let lock = NSLock()
+    private let fileURL: URL
+    private var minimumLevel: LogLevel
+    private var handle: FileHandle?
+
+    /// 5 MiB per segment, 5 historical segments kept.
+    public static let maxSegmentBytes: UInt64 = 5 * 1024 * 1024
+    public static let keptSegments = 5
+
+    public init(
+        fileURL: URL = AppPaths.logFile,
+        minimumLevel: LogLevel? = nil
+    ) {
+        self.fileURL = fileURL
+        #if DEBUG
+        self.minimumLevel = minimumLevel ?? .debug
+        #else
+        self.minimumLevel = minimumLevel ?? .info
+        #endif
+    }
+
+    public var level: LogLevel {
+        lock.lock()
+        defer { lock.unlock() }
+        return minimumLevel
+    }
+
+    /// Applied at startup AND on every settings save (issue #5, #158).
+    public func setLevel(_ level: LogLevel) {
+        lock.lock()
+        minimumLevel = level
+        lock.unlock()
+    }
+
+    /// `nil` → DEBUG-build default (.debug) / release (.info).
+    public func applySettings(_ settings: AppSettings) {
+        setLevel(settings.effectiveLogLevel)
+    }
+
+    public func shouldLog(_ level: LogLevel) -> Bool {
+        level.rank <= { lock.lock(); defer { lock.unlock() }; return minimumLevel }().rank
+    }
+
+    // MARK: - Writing
+
+    /// Appends a `YYYY-MM-DD HH:mm:ss.SSS [LEVEL] category: msg` line,
+    /// rotating first when the active segment exceeds 5 MiB.
+    public func write(level: LogLevel, category: String, message: String) {
+        guard shouldLog(level) else { return }
+        lock.lock()
+        defer { lock.unlock() }
+        rotateIfNeeded()
+        openIfNeeded()
+        let stamp = Self.timestamp()
+        let line = "\(stamp) [\(level.rawValue.uppercased())] \(category): \(message)\n"
+        if let data = line.data(using: .utf8) {
+            handle?.write(data)
+        }
+    }
+
+    private static let formatter: DateFormatter = {
+        let f = DateFormatter()
+        f.dateFormat = "yyyy-MM-dd HH:mm:ss.SSS"
+        f.locale = Locale(identifier: "en_US_POSIX")
+        return f
+    }()
+
+    private static func timestamp() -> String {
+        formatter.string(from: Date())
+    }
+
+    private func openIfNeeded() {
+        guard handle == nil else { return }
+        try? FileManager.default.createDirectory(
+            at: fileURL.deletingLastPathComponent(), withIntermediateDirectories: true
+        )
+        if !FileManager.default.fileExists(atPath: fileURL.path) {
+            FileManager.default.createFile(atPath: fileURL.path, contents: nil)
+        }
+        handle = try? FileHandle(forWritingTo: fileURL)
+        try? handle?.seekToEnd()
+    }
+
+    /// Shifts `iccery.log.4→.5`, `.3→.4`, …, `.log→.1` and resets the
+    /// writer. Oldest segment is deleted.
+    private func rotateIfNeeded() {
+        guard FileManager.default.fileExists(atPath: fileURL.path),
+              let attrs = try? FileManager.default.attributesOfItem(atPath: fileURL.path),
+              let size = attrs[.size] as? UInt64,
+              size >= Self.maxSegmentBytes
+        else { return }
+
+        try? handle?.close()
+        handle = nil
+        let fm = FileManager.default
+        let oldest = fileURL.appendingPathExtension("\(Self.keptSegments)")
+        try? fm.removeItem(at: oldest)
+        for i in stride(from: Self.keptSegments - 1, through: 1, by: -1) {
+            let src = fileURL.appendingPathExtension("\(i)")
+            let dst = fileURL.appendingPathExtension("\(i + 1)")
+            if fm.fileExists(atPath: src.path) {
+                try? fm.moveItem(at: src, to: dst)
+            }
+        }
+        try? fm.moveItem(at: fileURL, to: fileURL.appendingPathExtension("1"))
+    }
+
+    /// Tail of the active log for the settings dialog's "copy excerpt".
+    public func tailExcerpt(maxBytes: Int = 32 * 1024) -> String {
+        guard let data = try? Data(contentsOf: fileURL) else { return "" }
+        let slice = data.suffix(maxBytes)
+        return String(decoding: slice, as: UTF8.self)
+    }
+}

Packages/ICCeryCore/Sources/ICCeryCore/Settings/AppSettings.swift

@@ -0,0 +1,115 @@
+import Foundation
+
+/// A saved wizard preset slot (docs/22 §Presets). The preset *engine*
+/// lands in issue #11; for M1 the store only needs a Codable container.
+public struct CustomPreset: Codable, Equatable, Sendable {
+    public var name: String
+    /// Opaque per-stage form values — keyed by field id.
+    public var values: [String: String]
+
+    public init(name: String, values: [String: String] = [:]) {
+        self.name = name
+        self.values = values
+    }
+}
+
+/// Where `install_profile` drops finished profiles (docs/22).
+public enum InstallLocation: String, Codable, Sendable, CaseIterable {
+    case user
+    case system
+}
+
+/// `settings.json` model (docs/22). snake_case keys match the v1 file
+/// so field names stay identical across rewrites.
+public struct AppSettings: Codable, Equatable, Sendable {
+
+    /// User override for Argyll binaries; `nil` → bundled sidecars.
+    public var argyllBinaryDir: String?
+
+    /// Stored but **never applied to argv** — Stage 2's own instrument
+    /// select is the live source (docs/04 §0.1).
+    public var defaultInstrument: String?
+
+    /// `nil` → `.debug` in debug builds, `.info` in release (#158).
+    public var logLevel: LogLevel?
+
+    public var deltaEGoodMax: Double
+    public var deltaEWarningMax: Double
+    public var customPresets: [CustomPreset]
+    public var enableI1Pro2Leds: Bool
+    public var calibrationStaleDays: Int
+    public var defaultInstallLocation: InstallLocation
+    public var askBeforeOverwriteProfile: Bool
+    public var openColorPanelAfterInstall: Bool
+
+    public init(
+        argyllBinaryDir: String? = nil,
+        defaultInstrument: String? = nil,
+        logLevel: LogLevel? = nil,
+        deltaEGoodMax: Double = 2.0,
+        deltaEWarningMax: Double = 5.0,
+        customPresets: [CustomPreset] = [],
+        enableI1Pro2Leds: Bool = false,
+        calibrationStaleDays: Int = 30,
+        defaultInstallLocation: InstallLocation = .user,
+        askBeforeOverwriteProfile: Bool = true,
+        openColorPanelAfterInstall: Bool = false
+    ) {
+        self.argyllBinaryDir = argyllBinaryDir
+        self.defaultInstrument = defaultInstrument
+        self.logLevel = logLevel
+        self.deltaEGoodMax = deltaEGoodMax
+        self.deltaEWarningMax = deltaEWarningMax
+        self.customPresets = customPresets
+        self.enableI1Pro2Leds = enableI1Pro2Leds
+        self.calibrationStaleDays = calibrationStaleDays
+        self.defaultInstallLocation = defaultInstallLocation
+        self.askBeforeOverwriteProfile = askBeforeOverwriteProfile
+        self.openColorPanelAfterInstall = openColorPanelAfterInstall
+    }
+
+    public static let `default` = AppSettings()
+
+    /// Effective log level — runtime state, not just persistence (#158).
+    public var effectiveLogLevel: LogLevel {
+        if let logLevel { return logLevel }
+        #if DEBUG
+        return .debug
+        #else
+        return .info
+        #endif
+    }
+
+    enum CodingKeys: String, CodingKey {
+        case argyllBinaryDir = "argyll_binary_dir"
+        case defaultInstrument = "default_instrument"
+        case logLevel = "log_level"
+        case deltaEGoodMax = "delta_e_good_max"
+        case deltaEWarningMax = "delta_e_warning_max"
+        case customPresets = "custom_presets"
+        case enableI1Pro2Leds = "enable_i1pro2_leds"
+        case calibrationStaleDays = "calibration_stale_days"
+        case defaultInstallLocation = "default_install_location"
+        case askBeforeOverwriteProfile = "ask_before_overwrite_profile"
+        case openColorPanelAfterInstall = "open_color_panel_after_install"
+    }
+
+    /// UI-facing validation. Strings are part of the contract (issue #5).
+    public static let errorNegativeDeltaE = "ΔE thresholds cannot be negative."
+    public static let errorThresholdOrder =
+        "Good ΔE threshold must be strictly less than the warning threshold."
+
+    /// All validation errors, in declaration order. Empty = valid.
+    public func validate() -> [String] {
+        var errors: [String] = []
+        if deltaEGoodMax < 0 || deltaEWarningMax < 0 {
+            errors.append(Self.errorNegativeDeltaE)
+        }
+        if deltaEGoodMax >= deltaEWarningMax {
+            errors.append(Self.errorThresholdOrder)
+        }
+        return errors
+    }
+
+    public var isValid: Bool { validate().isEmpty }
+}

Packages/ICCeryCore/Sources/ICCeryCore/Settings/SettingsStore.swift

@@ -0,0 +1,47 @@
+import Foundation
+
+/// Persists `AppSettings` to
+/// `~/Library/Application Support/com.gronod.iccery2/settings.json`
+/// (issue #5 — the v1 path is never read).
+///
+/// Writes are atomic (`AtomicFileWriter`). Invalid/corrupt JSON falls
+/// back to defaults. Saving posts `settingsDidChange` so #20 can
+/// reclassify swatches.
+public final class SettingsStore: Sendable {
+
+    /// Posted on `NotificationCenter.default` after every successful save.
+    public static let settingsDidChange =
+        Notification.Name("com.gronod.iccery2.settingsDidChange")
+
+    public let fileURL: URL
+
+    public init(fileURL: URL = AppPaths.appDataDir.appendingPathComponent("settings.json")) {
+        self.fileURL = fileURL
+    }
+
+    public func load() -> AppSettings {
+        guard let data = try? Data(contentsOf: fileURL),
+              let settings = try? JSONDecoder().decode(AppSettings.self, from: data)
+        else {
+            return .default
+        }
+        return settings
+    }
+
+    /// Validates before persisting — throws `SettingsError` listing
+    /// every violation; nothing is written on failure.
+    public func save(_ settings: AppSettings) throws {
+        let errors = settings.validate()
+        guard errors.isEmpty else {
+            throw SettingsError.validationFailed(errors)
+        }
+        let encoder = JSONEncoder()
+        encoder.outputFormatting = [.prettyPrinted, .sortedKeys]
+        try AtomicFileWriter.write(encoder.encode(settings), to: fileURL)
+        NotificationCenter.default.post(name: Self.settingsDidChange, object: nil)
+    }
+
+    public enum SettingsError: Error, Equatable {
+        case validationFailed([String])
+    }
+}

Packages/ICCeryCore/Sources/ICCeryCore/Wizard/WizardGating.swift

@@ -0,0 +1,59 @@
+import Foundation
+
+/// Artefact-driven stage gating (issue #4, docs/06 §Stages).
+///
+/// Navigation is *disk*, not buttons: a stage unlocks only when its
+/// predecessor artefacts exist. Forward moves are gated; backward is
+/// always allowed. Gating is re-evaluated on window focus and on stage
+/// entry (#151 — files can disappear in Finder).
+public enum WizardGating {
+
+    /// Whether `stage` is reachable given the probed artefacts.
+    ///
+    /// - Stage 0 (calibrate): always — it is out-of-band, not gated.
+    /// - Stage 1: always.
+    /// - Stage 2: `.ti1` exists.
+    /// - Stage 3: `.ti1` **and** `.ti2`.
+    /// - Stage 4: `.ti3` exists (accepted measurement only — a `.ti2`
+    ///   alone never unlocks it; #109/#110).
+    /// - Stage 5: `.ti3` **and** `.icc`/`.icm`.
+    public static func isUnlocked(
+        _ stage: WizardStage,
+        artefacts: StageArtefacts
+    ) -> Bool {
+        switch stage {
+        case .calibrate:     return true
+        case .generate:      return true
+        case .layOutPrint:   return artefacts.stage1Complete
+        case .measure:       return artefacts.stage1Complete && artefacts.stage2Complete
+        case .buildProfile:  return artefacts.stage3Complete
+        case .verifyInstall: return artefacts.stage3Complete && artefacts.stage4Complete
+        }
+    }
+
+    /// Whether `go(to:)` may proceed. Backward moves and the current
+    /// stage are always allowed; forward moves must be unlocked.
+    public static func canNavigate(
+        to target: WizardStage,
+        from current: WizardStage,
+        artefacts: StageArtefacts
+    ) -> Bool {
+        if target == current { return true }
+        if target == .calibrate || current == .calibrate {
+            // Stage 0 is a side-trip, not stepper navigation.
+            return true
+        }
+        if target.rawValue < current.rawValue { return true }
+        return isUnlocked(target, artefacts: artefacts)
+    }
+
+    /// The deepest unlocked stepper stage — used when revalidation
+    /// locks the current stage (#151).
+    public static func deepestUnlocked(artefacts: StageArtefacts) -> WizardStage {
+        for stage in WizardStage.stepperStages.reversed()
+        where isUnlocked(stage, artefacts: artefacts) {
+            return stage
+        }
+        return .generate
+    }
+}

Packages/ICCeryCore/Sources/ICCeryCore/Wizard/WizardState.swift

@@ -0,0 +1,72 @@
+import Foundation
+
+/// Session mode (docs/06 §wizardState). `"calibration"` is set while
+/// Stage 0 is driving a `CAL_` chart through the same pipeline.
+public enum SessionMode: String, Codable, Sendable {
+    case profile
+    case calibration
+}
+
+/// Persisted wizard state (docs/06 §wizardState fields) —
+/// `wizard_state.json` in app data.
+public struct WizardState: Codable, Equatable, Sendable {
+    /// 0–5 (`WizardStage.rawValue`).
+    public var currentStage: Int
+    /// Run name without extension — never invented (#60).
+    public var basename: String
+    /// Working directory for artefacts; empty → `resolveSafeCwd` (#59).
+    public var cwd: String
+    /// Last spooled printer, for calibration drift history.
+    public var printerName: String?
+    public var sessionMode: SessionMode
+    /// May differ from `basename` after a `.ti3` import (#94).
+    public var profileBasename: String?
+
+    public init(
+        currentStage: Int = WizardStage.generate.rawValue,
+        basename: String = "",
+        cwd: String = "",
+        printerName: String? = nil,
+        sessionMode: SessionMode = .profile,
+        profileBasename: String? = nil
+    ) {
+        self.currentStage = currentStage
+        self.basename = basename
+        self.cwd = cwd
+        self.printerName = printerName
+        self.sessionMode = sessionMode
+        self.profileBasename = profileBasename
+    }
+
+    public static let `default` = WizardState()
+
+    /// The stage a saved `currentStage` resolves to, clamped to a valid
+    /// value (corrupt ints fall back to Stage 1).
+    public var stage: WizardStage {
+        WizardStage(rawValue: currentStage) ?? .generate
+    }
+}
+
+/// Atomic JSON persistence for `WizardState` (issue #4).
+public final class WizardStateStore: Sendable {
+    public let fileURL: URL
+
+    public init(
+        fileURL: URL = AppPaths.appDataDir.appendingPathComponent("wizard_state.json")
+    ) {
+        self.fileURL = fileURL
+    }
+
+    public func load() -> WizardState {
+        guard let data = try? Data(contentsOf: fileURL),
+              let state = try? JSONDecoder().decode(WizardState.self, from: data)
+        else { return .default }
+        return state
+    }
+
+    public func save(_ state: WizardState) throws {
+        let encoder = JSONEncoder()
+        encoder.outputFormatting = [.prettyPrinted, .sortedKeys]
+        try AtomicFileWriter.write(encoder.encode(state), to: fileURL)
+    }
+}

Resources/Argyll/mocks/chartread.mock

@@ -0,0 +1,75 @@
+#!/bin/bash
+# Mock script for chartread -u
+# This script simulates the behaviour of chartread for testing purposes.
+
+# Check for --xy argument or MOCK_XY_TABLE environment variable
+IS_XY=0
+for arg in "$@"; do
+    if [ "$arg" = "--xy" ]; then
+        IS_XY=1
+        break
+    fi
+done
+
+if [ "$IS_XY" = "1" ] || [ "${MOCK_XY_TABLE}" = "1" ]; then
+    echo "Place instrument on calibration tile and hit [Space] to calibrate."
+    read -r _calib
+    echo "Calibration successful."
+
+    echo "Please place sheet 1 of 1 on the table"
+    echo "hit return to continue, Esc or 'q' to give up"
+    read -r _sheet1
+
+    echo "locate patch A1 with the sight,"
+    echo "then hit return to continue"
+    read -r _fid1
+
+    echo "locate patch B24 with the sight,"
+    echo "then hit return to continue"
+    read -r _fid2
+
+    echo "Reading sheet 1..."
+    sleep 0.5
+
+    # Emit mock JSON for strip A
+    cat << 'EOF'
+ROW_COLORS_JSON: {"event": "row_complete", "row_id": "A", "row_index": 0, "total_rows": 2, "patch_count": 3, "patches": [{"id": "1", "loc": "A1", "is_pad": false, "device": [0.0, 50.0, 100.0], "expected": {"XYZ": [18.4210, 20.1234, 15.6789], "Lab": [51.98, -8.45, 12.32]}, "measured": {"XYZ": [18.5120, 20.0451, 15.7100], "Lab": [51.89, -8.31, 12.15]}}, {"id": "2", "loc": "A2", "is_pad": false, "device": [10.0, 60.0, 90.0], "expcted": {"Lab": [60.0, 10.0, -20.0]}, "measured": {"Lab": [60.1, 10.5, -19.5]}}, {"id": "3", "loc": "A3", "is_pad": true, "device": [100.0, 100.0, 100.0]}]}
+EOF
+
+    # Emit mock JSON for strip B
+    cat << 'EOF'
+ROW_COLORS_JSON: {"event": "row_complete", "row_id": "B", "row_index": 1, "total_rows": 2, "patch_count": 2, "patches": [{"id": "4", "loc": "B1", "is_pad": false, "device": [100.0, 0.0, 0.0], "expected": {"Lab": [40.0, 40.0, 40.0]}, "measured": {"Lab": [38.0, 41.0, 39.0]}}, {"id": "5", "loc": "B2", "is_pad": false, "device": [0.0, 100.0, 0.0], "expcted": {"Lab": [80.0, -50.0, 50.0]}, "measured": {"Lab": [79.0, -49.0, 51.0]}}]}
+EOF
+
+    echo "Sheet 1 of 1 read OK"
+    echo "Please remove last sheet from table"
+    exit 0
+fi
+
+# Handheld / strip reader simulation
+echo "Place instrument on calibration tile and hit [Space] to calibrate."
+
+# We don't really wait for input, just wait 1 second
+sleep 1
+echo "Calibration successful."
+echo "Hit [Space] to read strip A (or 's' to skip)."
+
+sleep 1
+echo "Reading strip A..."
+
+# Emit mock JSON for strip A
+cat << 'EOF'
+ROW_COLORS_JSON: {"event": "row_complete", "row_id": "A", "row_index": 0, "total_rows": 2, "patch_count": 3, "patches": [{"id": "1", "loc": "A1", "is_pad": false, "device": [0.0, 50.0, 100.0], "expected": {"XYZ": [18.4210, 20.1234, 15.6789], "Lab": [51.98, -8.45, 12.32]}, "measured": {"XYZ": [18.5120, 20.0451, 15.7100], "Lab": [51.89, -8.31, 12.15]}}, {"id": "2", "loc": "A2", "is_pad": false, "device": [10.0, 60.0, 90.0], "expcted": {"Lab": [60.0, 10.0, -20.0]}, "measured": {"Lab": [60.1, 10.5, -19.5]}}, {"id": "3", "loc": "A3", "is_pad": true, "device": [100.0, 100.0, 100.0]}]}
+EOF
+
+echo "Hit [Space] to read strip B (or 's' to skip)."
+sleep 1
+echo "Reading strip B..."
+
+# Emit mock JSON for strip B
+cat << 'EOF'
+ROW_COLORS_JSON: {"event": "row_complete", "row_id": "B", "row_index": 1, "total_rows": 2, "patch_count": 2, "patches": [{"id": "4", "loc": "B1", "is_pad": false, "device": [100.0, 0.0, 0.0], "expected": {"Lab": [40.0, 40.0, 40.0]}, "measured": {"Lab": [38.0, 41.0, 39.0]}}, {"id": "5", "loc": "B2", "is_pad": false, "device": [0.0, 100.0, 0.0], "expected": {"Lab": [80.0, -50.0, 50.0]}, "measured": {"Lab": [79.0, -49.0, 51.0]}}]}
+EOF
+
+echo "Ready to read... done."
+exit 0

Resources/Argyll/mocks/colprof.mock

@@ -0,0 +1,20 @@
+#!/bin/bash
+# Mock script for colprof
+# Simulates colprof execution and outputs progress log
+
+basename="$1"
+# Find last argument if -D or other flags are used
+for arg in "$@"; do
+    basename="$arg"
+done
+
+echo "colprof: Starting profile calculation for $basename"
+sleep 1
+echo "Gamut mapping calculation..."
+sleep 1
+echo "Fitting cLUT grid points..."
+sleep 1
+echo "Writing ICC profile $basename.icc..."
+touch "$basename.icc"
+echo "Done."
+exit 0

Resources/Argyll/mocks/profcheck.mock

@@ -0,0 +1,12 @@
+#!/bin/bash
+# Mock script for profcheck
+# Simulates real ArgyllCMS profcheck -v -k -s -u output
+
+echo "profcheck: Checking profile accuracy..."
+echo "No of test patches = 52"
+sleep 1
+cat << 'EOF'
+{"event": "report", "peak_de2000": 2.41, "avg_de2000": 0.85, "rms": 1.02}
+EOF
+echo "Profile check complete, errors(CIEDE2000): max. = 2.41, avg. = 0.85, RMS = 1.02"
+exit 0

Sources/ICCery/FileDialogService.swift

@@ -0,0 +1,112 @@
+import AppKit
+import UniformTypeIdentifiers
+
+/// Dedicated NSOpenPanel / NSSavePanel wrappers (issue #6) — one method
+/// per purpose, matching the v1 `select_*` commands (docs/21 §Dialogs).
+/// No call site shares a generic picker (#103/#210/#211).
+@MainActor
+final class FileDialogService {
+
+    static let shared = FileDialogService()
+    private init() {}
+
+    // MARK: - selectDirectory
+
+    /// `#btnBrowse` — working directory for Argyll artefacts.
+    /// Defaults to Documents (docs/06 §Empty cwd).
+    func selectDirectory(startingAt start: URL? = nil) -> URL? {
+        let panel = NSOpenPanel()
+        panel.canChooseDirectories = true
+        panel.canChooseFiles = false
+        panel.allowsMultipleSelection = false
+        panel.directoryURL = start
+            ?? FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first
+        panel.prompt = "Choose"
+        return run(panel)
+    }
+
+    // MARK: - Dedicated open pickers
+
+    /// `selectTargetFile` — **save** panel for the new `.ti1` target.
+    func selectTargetFile(startingAt start: URL? = nil) -> URL? {
+        let panel = NSSavePanel()
+        panel.nameFieldStringValue = "target.ti1"
+        panel.allowedContentTypes = utTypes(["ti1"])
+        panel.allowsOtherFileTypes = false
+        panel.directoryURL = start
+        panel.message = "Choose the .ti1 target file to create"
+        return run(panel)
+    }
+
+    /// `selectExistingTarget` — open `.ti1`/`.ti2` (docs/06 §Resume, #140).
+    func selectExistingTarget(startingAt start: URL? = nil) -> URL? {
+        open(extensions: ["ti1", "ti2"], startingAt: start,
+             message: "Open an existing target (.ti1 or .ti2)")
+    }
+
+    /// `selectProfileFile` — `.icc`/`.icm`/`.mpp` only — **never** `.ti*`
+    /// (#172: the profile filter must not accept datasets).
+    func selectProfileFile(startingAt start: URL? = nil) -> URL? {
+        open(extensions: ["icc", "icm", "mpp"], startingAt: start,
+             message: "Choose an ICC/ICM profile or measurement preconditioning file")
+    }
+
+    /// `selectSpectrumFile` — `.sp` illuminant spectrum (colprof -i).
+    func selectSpectrumFile(startingAt start: URL? = nil) -> URL? {
+        open(extensions: ["sp"], startingAt: start,
+             message: "Choose a custom illuminant spectrum (.sp)")
+    }
+
+    /// `selectDatasetFile` — open a measured dataset (`.ti3`, `.txt`,
+    /// `.cgats`, `.csv`). Always an *open* dialog, never save (#211).
+    func selectDatasetFile(startingAt start: URL? = nil) -> URL? {
+        open(extensions: ["ti3", "txt", "cgats", "csv"], startingAt: start,
+             message: "Import a measured dataset")
+    }
+
+    /// `selectCsvSavePath` — verification-history CSV export.
+    func selectCsvSavePath(startingAt start: URL? = nil) -> URL? {
+        let panel = NSSavePanel()
+        panel.nameFieldStringValue = "verification-history.csv"
+        panel.allowedContentTypes = utTypes(["csv"])
+        panel.allowsOtherFileTypes = false
+        panel.directoryURL = start
+        return run(panel)
+    }
+
+    /// `selectCalFile` — `.cal` calibration curves.
+    func selectCalFile(startingAt start: URL? = nil) -> URL? {
+        open(extensions: ["cal"], startingAt: start,
+             message: "Choose a calibration file (.cal)")
+    }
+
+    // MARK: - Internals (private — not a shared public picker API)
+
+    private func open(
+        extensions: [String],
+        startingAt start: URL?,
+        message: String?
+    ) -> URL? {
+        let panel = NSOpenPanel()
+        panel.canChooseDirectories = false
+        panel.canChooseFiles = true
+        panel.allowsMultipleSelection = false
+        panel.allowedContentTypes = utTypes(extensions)
+        panel.allowsOtherFileTypes = true
+        panel.directoryURL = start
+        if let message { panel.message = message }
+        return run(panel)
+    }
+
+    private func utTypes(_ extensions: [String]) -> [UTType] {
+        extensions.compactMap { UTType(filenameExtension: $0) }
+    }
+
+    private func run(_ panel: NSOpenPanel) -> URL? {
+        panel.runModal() == .OK ? panel.url : nil
+    }
+
+    private func run(_ panel: NSSavePanel) -> URL? {
+        panel.runModal() == .OK ? panel.url : nil
+    }
+}

Sources/ICCery/ICCeryApp.swift

@@ -1,4 +1,5 @@
 import AppKit
+import ICCeryCore
 import SwiftUI
 
 @main
@@ -6,6 +7,13 @@ struct ICCeryApp: App {
     @NSApplicationDelegateAdaptor(AppDelegate.self) private var appDelegate
     @State private var model = WizardViewModel()
 
+    init() {
+        try? AppPaths.ensureDirectories()
+        // Log level is runtime state — apply persisted settings at
+        // startup (#158); the Settings sheet re-applies on save.
+        LogSink.shared.applySettings(SettingsStore().load())
+    }
+
     var body: some Scene {
         // Single fixed window (docs/21 §Shell: 1280×800, min 1100×700).
         Window("ICCery", id: "main") {
@@ -19,15 +27,24 @@ struct ICCeryApp: App {
     }
 }
 
-/// AppDelegate: quit when the single window closes, and give later
-/// milestones a hook to `killAll` Argyll children before teardown
-/// (#147/#149 — wired once ProcessManager exists in #2).
+/// AppDelegate: quit when the single window closes, and `killAll` Argyll
+/// children before teardown (#147/#149). Termination is deferred until
+/// `killAll` has signaled every child so `chartread` can park an XY head
+/// when the UI already sent `q\n`.
 final class AppDelegate: NSObject, NSApplicationDelegate {
+    private var terminationRequested = false
+
     func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool {
         true
     }
 
-    func applicationWillTerminate(_ notification: Notification) {
-        // Issue #2+: ProcessManager.shared.killAll()
+    func applicationShouldTerminate(_ sender: NSApplication) -> NSApplication.TerminateReply {
+        guard !terminationRequested else { return .terminateNow }
+        terminationRequested = true
+        Task {
+            await ProcessManager.shared.killAll()
+            NSApplication.shared.reply(toApplicationShouldTerminate: true)
+        }
+        return .terminateLater
     }
 }

Sources/ICCery/RootView.swift

@@ -1,3 +1,4 @@
+import AppKit
 import SwiftUI
 
 /// Root layout: 270 pt sidebar + main stage area with the notification
@@ -28,16 +29,15 @@ struct RootView: View {
         }
         .frame(minWidth: 1100, minHeight: 700)
         .background(Theme.background)
+        // #151: re-probe artefacts when the window regains focus —
+        // files deleted in Finder must re-lock stages.
+        .onReceive(
+            NotificationCenter.default.publisher(
+                for: NSWindow.didBecomeKeyNotification
+            )
+        ) { _ in model.windowDidBecomeKey() }
         .sheet(isPresented: $showingSettings) {
-            // Full settings dialog lands in issue #5.
-            VStack(spacing: 12) {
-                Text("Settings").font(.headline)
-                Text("Implemented in issue #5.")
-                    .foregroundStyle(.secondary)
-                Button("Close") { showingSettings = false }
-            }
-            .padding(24)
-            .frame(width: 420)
+            SettingsView()
         }
         .alert("ICCery 2.0.0", isPresented: $showingAbout) {
             Button("OK") {}

Sources/ICCery/SettingsView.swift

@@ -0,0 +1,169 @@
+import SwiftUI
+import ICCeryCore
+
+/// Settings sheet (issue #5, docs/21 §Settings). Dark-theme Form with
+/// the full v1 field set; ΔE validation shows inline under the fields.
+struct SettingsView: View {
+    @State var model = SettingsViewModel()
+    @Environment(\.dismiss) private var dismiss
+
+    private static let instruments: [(code: String, label: String)] = [
+        ("i1", "X-Rite i1Pro / i1Pro 2"),
+        ("p3", "X-Rite i1Pro 3 / 3 Plus"),
+        ("CM", "ColorMunki"),
+        ("SS", "Specbos / Spectraval"),
+        ("20", "Gretag i1Display 2"),
+        ("22", "X-Rite i1Display Pro / ColorMunki Display"),
+        ("41", "Datacolor Spyder 4/5"),
+        ("51", "Spyder X"),
+    ]
+
+    var body: some View {
+        VStack(spacing: 0) {
+            Form {
+                Section("Argyll") {
+                    HStack {
+                        TextField(
+                            "Bundled sidecars",
+                            text: Binding(
+                                get: { model.settings.argyllBinaryDir ?? "" },
+                                set: {
+                                    model.settings.argyllBinaryDir =
+                                        $0.isEmpty ? nil : $0
+                                }
+                            )
+                        )
+                        Button("Browse…") {
+                            if let dir = FileDialogService.shared.selectDirectory() {
+                                model.settings.argyllBinaryDir = dir.path
+                            }
+                        }
+                    }
+                    Text("Leave empty to use the bundled Argyll tools.")
+                        .font(.caption)
+                        .foregroundStyle(.secondary)
+
+                    Picker(
+                        "Default instrument",
+                        selection: Binding(
+                            get: { model.settings.defaultInstrument ?? "" },
+                            set: {
+                                model.settings.defaultInstrument =
+                                    $0.isEmpty ? nil : $0
+                            }
+                        )
+                    ) {
+                        Text("None").tag("")
+                        ForEach(Self.instruments, id: \.code) {
+                            Text($0.label).tag($0.code)
+                        }
+                    }
+                    Text("Display-only — Stage 2's instrument select is used for actual runs.")
+                        .font(.caption)
+                        .foregroundStyle(.secondary)
+
+                    Toggle(
+                        "Enable i1Pro 2 LEDs",
+                        isOn: $model.settings.enableI1Pro2Leds
+                    )
+                }
+
+                Section("Verification") {
+                    HStack {
+                        Text("Good ΔE ≤")
+                        TextField(
+                            "2.0",
+                            value: $model.settings.deltaEGoodMax,
+                            format: .number
+                        )
+                        .frame(width: 60)
+                        Text("Warning ΔE ≤")
+                        TextField(
+                            "5.0",
+                            value: $model.settings.deltaEWarningMax,
+                            format: .number
+                        )
+                        .frame(width: 60)
+                    }
+                    ForEach(model.validationErrors, id: \.self) { error in
+                        Text(error)
+                            .font(.caption)
+                            .foregroundStyle(.red)
+                    }
+                }
+
+                Section("Calibration") {
+                    HStack {
+                        Text("Stale after")
+                        TextField(
+                            "30",
+                            value: $model.settings.calibrationStaleDays,
+                            format: .number
+                        )
+                        .frame(width: 60)
+                        Text("days")
+                    }
+                }
+
+                Section("Profile install") {
+                    Picker(
+                        "Install location",
+                        selection: $model.settings.defaultInstallLocation
+                    ) {
+                        Text("User library").tag(InstallLocation.user)
+                        Text("System library").tag(InstallLocation.system)
+                    }
+                    Toggle(
+                        "Ask before overwriting a profile",
+                        isOn: $model.settings.askBeforeOverwriteProfile
+                    )
+                    Toggle(
+                        "Open ColorSync after install",
+                        isOn: $model.settings.openColorPanelAfterInstall
+                    )
+                }
+
+                Section("Logging") {
+                    Picker(
+                        "Log level",
+                        selection: Binding(
+                            get: { model.settings.logLevel },
+                            set: { model.settings.logLevel = $0 }
+                        )
+                    ) {
+                        Text("Default").tag(LogLevel?.none)
+                        ForEach(LogLevel.allCases, id: \.self) {
+                            Text($0.rawValue.capitalized).tag(LogLevel?.some($0))
+                        }
+                    }
+                    HStack {
+                        Button("Open log folder") { model.openLogFolder() }
+                        Button("Copy path") { model.copyLogPath() }
+                        Button("Copy excerpt") { model.copyLogExcerpt() }
+                    }
+                }
+            }
+            .formStyle(.grouped)
+
+            Divider()
+
+            HStack {
+                if model.savedFlash {
+                    Text("Saved")
+                        .foregroundStyle(.green)
+                        .font(.callout)
+                }
+                Spacer()
+                Button("Cancel") { dismiss() }
+                    .keyboardShortcut(.cancelAction)
+                Button("Save") {
+                    if model.save() { dismiss() }
+                }
+                .keyboardShortcut(.defaultAction)
+            }
+            .padding(12)
+        }
+        .frame(width: 560, height: 620)
+        .background(Theme.background)
+    }
+}

Sources/ICCery/SettingsViewModel.swift

@@ -0,0 +1,68 @@
+import AppKit
+import Foundation
+import ICCeryCore
+
+/// Backs the Settings sheet (issue #5). Load → edit → save with
+/// validation; the log level is applied live via `LogSink` (#158) and a
+/// `settingsDidChange` notification fans out to #20.
+@MainActor
+@Observable
+final class SettingsViewModel {
+
+    var settings: AppSettings
+    var validationErrors: [String] = []
+    var savedFlash = false
+
+    private let store: SettingsStore
+    private let sink: LogSink
+
+    init(store: SettingsStore = SettingsStore(), sink: LogSink = .shared) {
+        self.store = store
+        self.sink = sink
+        self.settings = store.load()
+    }
+
+    /// Persists after validation. Returns false (and shows inline
+    /// errors) when the form is invalid.
+    @discardableResult
+    func save() -> Bool {
+        validationErrors = settings.validate()
+        guard validationErrors.isEmpty else { return false }
+        do {
+            try store.save(settings)
+            sink.applySettings(settings)
+            savedFlash = true
+            Task {
+                try? await Task.sleep(for: .seconds(1.5))
+                savedFlash = false
+            }
+            return true
+        } catch {
+            validationErrors = ["Could not save settings: \(error.localizedDescription)"]
+            return false
+        }
+    }
+
+    // MARK: - Log helpers
+
+    var logFileURL: URL { AppPaths.logFile }
+
+    func openLogFolder() {
+        try? FileManager.default.createDirectory(
+            at: AppPaths.logDir, withIntermediateDirectories: true
+        )
+        NSWorkspace.shared.selectFile(
+            AppPaths.logFile.path, inFileViewerRootedAtPath: AppPaths.logDir.path
+        )
+    }
+
+    func copyLogPath() {
+        NSPasteboard.general.clearContents()
+        NSPasteboard.general.setString(AppPaths.logFile.path, forType: .string)
+    }
+
+    func copyLogExcerpt() {
+        NSPasteboard.general.clearContents()
+        NSPasteboard.general.setString(sink.tailExcerpt(), forType: .string)
+    }
+}

Sources/ICCery/SidebarView.swift

@@ -60,8 +60,8 @@ struct SidebarView: View {
                     StepperRow(
                         stage: stage,
                         isActive: model.stage == stage,
-                        // Only Stage 1 until artefact gating lands in #4.
-                        isEnabled: stage == .generate
+                        // Artefact gating (issue #4) — disk is truth.
+                        isEnabled: model.isUnlocked(stage)
                     ) {
                         model.go(to: stage)
                     }

Sources/ICCery/WizardViewModel.swift

@@ -2,44 +2,142 @@ import Foundation
 import Observation
 import ICCeryCore
 
-/// Wizard shell state (issue #1). Artefact gating, persistence and the
-/// "open existing" flow land in issue #4.
+/// Wizard state machine + artefact gating (issue #4, docs/06).
+///
+/// `wizardState` fields (`currentStage`, `basename`, `cwd`,
+/// `printerName`, `sessionMode`, `profileBasename`) are persisted to
+/// `wizard_state.json`; unlocks come from `ArtefactProbe.verify` —
+/// navigation is disk, not buttons.
 @MainActor
 @Observable
 final class WizardViewModel {
-    /// Currently displayed stage.
-    var stage: WizardStage = .generate
+
+    // MARK: - wizardState fields (persisted)
+
+    var stage: WizardStage {
+        didSet { if stage != oldValue { persist() } }
+    }
+    /// `wizardState.basename` — empty until a real artefact names it (#60).
+    var basename: String {
+        didSet { if basename != oldValue { refreshGating(); persist() } }
+    }
+    /// `wizardState.cwd` — resolved via `resolveSafeCwd` (#59).
+    var workingDirectory: URL? {
+        didSet { if workingDirectory != oldValue { refreshGating(); persist() } }
+    }
+    var printerName: String? {
+        didSet { if printerName != oldValue { persist() } }
+    }
+    var sessionMode: SessionMode {
+        didSet { if sessionMode != oldValue { persist() } }
+    }
+    /// `profileBasename` may differ after a `.ti3` import (#94).
+    var profileBasename: String? {
+        didSet { if profileBasename != oldValue { persist() } }
+    }
+
+    // MARK: - Ephemeral
 
     /// Banner notice currently displayed (`#wizardNotification`).
     var notice: Notice?
+    /// Current artefact probe result; recomputed on `refreshGating()`.
+    private(set) var artefacts = StageArtefacts()
 
-    /// Target basename shared across stages (`targetBasename`).
-    var basename: String = ""
-
-    /// Working directory for all Argyll artefacts.
-    var workingDirectory: URL?
-
-    /// Printer queue selected in Stage 2; retained across stages.
-    var printerName: String?
-
+    private let stateStore: WizardStateStore
     private var noticeDismissTask: Task<Void, Never>?
 
-    /// `true` while Stage 0 (printer calibration) is shown instead of a
-    /// stepper stage.
+    init(stateStore: WizardStateStore = WizardStateStore()) {
+        self.stateStore = stateStore
+        let s = stateStore.load()
+        self.stage = s.stage
+        self.basename = s.basename
+        self.workingDirectory = s.cwd.isEmpty ? nil : URL(fileURLWithPath: s.cwd)
+        self.printerName = s.printerName
+        self.sessionMode = s.sessionMode
+        self.profileBasename = s.profileBasename
+        refreshGating()
+        // A restored stage may have been locked since (#151).
+        if !WizardGating.isUnlocked(stage, artefacts: artefacts), stage != .calibrate {
+            stage = WizardGating.deepestUnlocked(artefacts: artefacts)
+        }
+    }
+
+    // MARK: - Gating
+
+    /// `isUnlocked` for the sidebar stepper.
+    func isUnlocked(_ stage: WizardStage) -> Bool {
+        WizardGating.isUnlocked(stage, artefacts: artefacts)
+    }
+
+    /// `true` while Stage 0 (printer calibration) is shown.
     var isCalibrating: Bool { stage == .calibrate }
 
-    func go(to stage: WizardStage) {
-        self.stage = stage
+    /// Re-probes the artefact directory and re-locks (#151). Called on
+    /// window focus, stage entry, and basename/cwd changes.
+    func refreshGating() {
+        guard !basename.isEmpty, let dir = effectiveWorkingDirectory else {
+            artefacts = StageArtefacts()
+            return
+        }
+        artefacts = ArtefactProbe.verify(basename: basename, cwd: dir)
+    }
+
+    /// `setTarget(basename, cwd)` — validates the basename (no `/`, `\`,
+    /// `..`; no placeholders — #60) and resolves the cwd (#59).
+    func setTarget(basename: String, workingDirectory: URL?) {
+        do {
+            self.basename = try PathSecurity.sanitizeBasename(basename)
+        } catch {
+            showNotice("Invalid target name.", kind: .error)
+            return
+        }
+        self.workingDirectory = PathSecurity.resolveSafeCwd(workingDirectory)
+    }
+
+    /// cwd never stays empty once a basename exists (#59).
+    var effectiveWorkingDirectory: URL? {
+        if let workingDirectory { return workingDirectory }
+        return basename.isEmpty ? nil : PathSecurity.resolveSafeCwd(nil)
+    }
+
+    // MARK: - Navigation
+
+    /// `navigateToStage(n)` — refuses locked forward moves with a
+    /// warning banner; backward is always allowed (docs/06).
+    func go(to target: WizardStage) {
+        guard target != .calibrate else { enterCalibration(); return }
+        if WizardGating.canNavigate(to: target, from: stage, artefacts: artefacts) {
+            stage = target
+        } else {
+            showNotice(
+                "Stage \(target.stepperIndex ?? 0) is locked — the required artefact is missing.",
+                kind: .warning
+            )
+        }
     }
 
     func enterCalibration() {
+        sessionMode = .calibration
         stage = .calibrate
     }
 
     func exitCalibration() {
+        sessionMode = .profile
         stage = .generate
     }
 
+    /// Window-focus hook (#151): files deleted in Finder re-lock stages.
+    /// If the current stage re-locked, fall back to the deepest unlocked.
+    func windowDidBecomeKey() {
+        refreshGating()
+        if stage != .calibrate,
+           !WizardGating.isUnlocked(stage, artefacts: artefacts) {
+            stage = WizardGating.deepestUnlocked(artefacts: artefacts)
+        }
+    }
+
+    // MARK: - Notice
+
     func showNotice(_ text: String, kind: Notice.Kind = .info, autoHideAfter: TimeInterval? = 6) {
         noticeDismissTask?.cancel()
         let notice = Notice(kind: kind, text: text, autoHideAfter: autoHideAfter)
@@ -59,4 +157,18 @@ final class WizardViewModel {
         noticeDismissTask?.cancel()
         notice = nil
     }
+
+    // MARK: - Persistence
+
+    private func persist() {
+        let state = WizardState(
+            currentStage: stage.rawValue,
+            basename: basename,
+            cwd: workingDirectory?.path ?? "",
+            printerName: printerName,
+            sessionMode: sessionMode,
+            profileBasename: profileBasename
+        )
+        try? stateStore.save(state)
+    }
 }

Tests/ICCeryCoreTests/ArtefactFilesTests.swift

@@ -0,0 +1,124 @@
+import Testing
+import Foundation
+import ImageIO
+import UniformTypeIdentifiers
+@testable import ICCeryCore
+
+private func tempURL(_ name: String) -> URL {
+    FileManager.default.temporaryDirectory
+        .appendingPathComponent("iccery-af-\(UUID().uuidString)")
+        .appendingPathComponent(name)
+}
+
+@Suite("Ti2Header")
+struct Ti2HeaderTests {
+    @Test func parsesKeywordsAndSibling() throws {
+        let dir = FileManager.default.temporaryDirectory
+            .appendingPathComponent("iccery-ti2-\(UUID().uuidString)")
+        try FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
+        try """
+        CTI2
+        TARGET_INSTRUMENT "i1iO"
+        NUMBER_OF_FIELDS 9
+        NUMBER_OF_SETS 800
+        NUMBER_OF_PAGES 3
+        BEGIN_DATA_FORMAT
+        SAMPLE_ID RGB_R
+        END_DATA_FORMAT
+        """.write(to: dir.appendingPathComponent("job.ti2"), atomically: true, encoding: .utf8)
+        try "CGATS".write(
+            to: dir.appendingPathComponent("job.ti1"), atomically: true, encoding: .utf8
+        )
+
+        let h = Ti2Header.parse(dir.appendingPathComponent("job.ti2"))
+        #expect(h.instrument == "i1iO")
+        #expect(h.patchCount == 800)
+        #expect(h.pageCount == 3)
+        #expect(h.hasSiblingTi1)
+    }
+
+    @Test func missingFileYieldsEmptyHeader() {
+        let h = Ti2Header.parse(URL(fileURLWithPath: "/nonexistent/x.ti2"))
+        #expect(h.instrument == nil && h.patchCount == nil && !h.hasSiblingTi1)
+    }
+
+    @Test func numberOfFieldsIsNotPatchCount() throws {
+        let url = tempURL("t.ti2")
+        try FileManager.default.createDirectory(
+            at: url.deletingLastPathComponent(), withIntermediateDirectories: true
+        )
+        try "NUMBER_OF_FIELDS 9\nNUMBER_OF_SETS 52\nBEGIN_DATA\n".write(
+            to: url, atomically: true, encoding: .utf8
+        )
+        #expect(Ti2Header.parse(url).patchCount == 52)
+    }
+}
+
+@Suite("TiffPreview")
+struct TiffPreviewTests {
+    /// Builds a real 2000×1000 TIFF in a temp dir via ImageIO.
+    private func makeTiff(width: Int = 2000, height: Int = 1000) throws -> URL {
+        let url = tempURL("big.tif")
+        try FileManager.default.createDirectory(
+            at: url.deletingLastPathComponent(), withIntermediateDirectories: true
+        )
+        let colorSpace = CGColorSpace(name: CGColorSpace.sRGB)!
+        let ctx = CGContext(
+            data: nil, width: width, height: height,
+            bitsPerComponent: 8, bytesPerRow: width * 4,
+            space: colorSpace,
+            bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+        )!
+        ctx.setFillColor(CGColor(red: 0.5, green: 0.5, blue: 0.5, alpha: 1))
+        ctx.fill(CGRect(x: 0, y: 0, width: width, height: height))
+        let image = ctx.makeImage()!
+
+        guard let dest = CGImageDestinationCreateWithURL(
+            url as CFURL, UTType.tiff.identifier as CFString, 1, nil
+        ) else { throw CocoaError(.fileWriteUnknown) }
+        CGImageDestinationAddImage(dest, image, nil)
+        guard CGImageDestinationFinalize(dest) else { throw CocoaError(.fileWriteUnknown) }
+        return url
+    }
+
+    @Test func producesCappedPNG() throws {
+        let tiff = try makeTiff()
+        let png = TiffPreview.previewPNG(tiff: tiff)
+        #expect(png != nil)
+        // PNG magic
+        #expect(png!.prefix(8) == Data([0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A]))
+        // Verify the cap by decoding the thumbnail header.
+        let src = CGImageSourceCreateWithData(png! as CFData, nil)!
+        let img = CGImageSourceCreateImageAtIndex(src, 0, nil)!
+        #expect(max(img.width, img.height) <= TiffPreview.maxEdge)
+        #expect(img.width == 1200)
+    }
+
+    @Test func nonTiffReturnsNil() throws {
+        let url = tempURL("not-tiff.txt")
+        try FileManager.default.createDirectory(
+            at: url.deletingLastPathComponent(), withIntermediateDirectories: true
+        )
+        try "hello".write(to: url, atomically: true, encoding: .utf8)
+        #expect(TiffPreview.previewPNG(tiff: url) == nil)
+    }
+}
+
+@Suite("ArtefactFiles")
+struct ArtefactFilesTests {
+    @Test func base64RoundTrip() throws {
+        let url = tempURL("a.txt")
+        try FileManager.default.createDirectory(
+            at: url.deletingLastPathComponent(), withIntermediateDirectories: true
+        )
+        try "hello".write(to: url, atomically: true, encoding: .utf8)
+        let b64 = try ArtefactFiles.readBase64(url)
+        #expect(Data(base64Encoded: b64) == Data("hello".utf8))
+    }
+
+    @Test func defaultWorkingDirExists() {
+        #expect(FileManager.default.fileExists(
+            atPath: ArtefactFiles.defaultWorkingDirectory().path
+        ))
+    }
+}

Tests/ICCeryCoreTests/BinaryResolverTests.swift

@@ -0,0 +1,83 @@
+import Testing
+import Foundation
+@testable import ICCeryCore
+
+@Suite("BinaryResolver")
+struct BinaryResolverTests {
+
+    private func makeTree(_ body: (URL) throws -> Void) throws -> URL {
+        let root = FileManager.default.temporaryDirectory
+            .appendingPathComponent("iccery-resolver-\(UUID().uuidString)")
+        try FileManager.default.createDirectory(at: root, withIntermediateDirectories: true)
+        try body(root)
+        return root
+    }
+
+    private func touch(_ url: URL, executable: Bool = true) throws {
+        FileManager.default.createFile(atPath: url.path, contents: Data())
+        if executable {
+            try FileManager.default.setAttributes(
+                [.posixPermissions: 0o755], ofItemAtPath: url.path
+            )
+        }
+    }
+
+    @Test func overrideDirWinsWhenFileExists() throws {
+        let override = try makeTree { root in
+            try touch(root.appendingPathComponent("targen"))
+        }
+        let bundled = try makeTree { _ in }
+        let r = BinaryResolver(bundledRoot: bundled, overrideDir: override)
+        #expect(r.resolve("targen") == override.appendingPathComponent("targen"))
+    }
+
+    @Test func overrideFallsThroughWhenMissing() throws {
+        let override = try makeTree { _ in }
+        let bundled = try makeTree { root in
+            let dir = root.appendingPathComponent("macos-universal")
+            try FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
+            try touch(dir.appendingPathComponent("instlist"))
+        }
+        let r = BinaryResolver(bundledRoot: bundled, overrideDir: override)
+        #expect(r.resolve("targen").path.contains("macos-universal/targen"))
+    }
+
+    @Test func universalPreferredWhenMarkerPresent() throws {
+        let bundled = try makeTree { root in
+            for dir in ["macos-universal", "macos-x86_64"] {
+                let d = root.appendingPathComponent(dir)
+                try FileManager.default.createDirectory(at: d, withIntermediateDirectories: true)
+                try touch(d.appendingPathComponent("instlist"))
+            }
+        }
+        let r = BinaryResolver(bundledRoot: bundled)
+        #expect(r.platformDir() == "macos-universal")
+    }
+
+    @Test func fallsBackToArchDir() throws {
+        let bundled = try makeTree { root in
+            let d = root.appendingPathComponent("macos-x86_64")
+            try FileManager.default.createDirectory(at: d, withIntermediateDirectories: true)
+            try touch(d.appendingPathComponent("instlist"))
+        }
+        let r = BinaryResolver(
+            bundledRoot: bundled,
+            archDirs: ["macos-universal", "macos-x86_64"]
+        )
+        #expect(r.platformDir() == "macos-x86_64")
+    }
+
+    @Test func missingEverythingReturnsConstructedPath() throws {
+        let bundled = try makeTree { _ in }
+        let r = BinaryResolver(bundledRoot: bundled)
+        // v1 semantic: path is returned; spawn surfaces the error.
+        #expect(r.resolve("targen").path.hasSuffix("macos-universal/targen"))
+        #expect(!r.exists(r.resolve("targen")))
+    }
+
+    @Test func mockAndGamutPaths() throws {
+        let r = BinaryResolver(bundledRoot: URL(fileURLWithPath: "/x"))
+        #expect(r.mock("chartread").path == "/x/mocks/chartread.mock")
+        #expect(r.referenceGamut("sRGB.gam").path == "/x/reference_gamuts/sRGB.gam")
+    }
+}

Tests/ICCeryCoreTests/FileHelpersTests.swift

@@ -0,0 +1,129 @@
+import Testing
+import Foundation
+@testable import ICCeryCore
+
+private func tempDir(_ name: String = UUID().uuidString) throws -> URL {
+    let url = FileManager.default.temporaryDirectory
+        .appendingPathComponent("iccery-files-\(name)")
+    try FileManager.default.createDirectory(at: url, withIntermediateDirectories: true)
+    return url
+}
+
+private func touch(_ url: URL, _ contents: String = "x") throws {
+    try contents.write(to: url, atomically: true, encoding: .utf8)
+}
+
+@Suite("PathSecurity")
+struct PathSecurityTests {
+    @Test func rejectsTraversalAndSeparators() {
+        for bad in ["a/b", "a\\b", "..", "a/../b", "", "..x"] {
+            #expect(!PathSecurity.isValidBasename(bad))
+            #expect(throws: PathSecurity.Error.self) {
+                try PathSecurity.sanitizeBasename(bad)
+            }
+        }
+    }
+
+    @Test func acceptsNormalNames() {
+        for good in ["target", "My Target 01", "écheneau-ümläut", "a.b"] {
+            #expect(PathSecurity.isValidBasename(good))
+        }
+    }
+
+    @Test func resolveSafeCwdPrefersExplicit() throws {
+        let dir = try tempDir()
+        #expect(PathSecurity.resolveSafeCwd(dir) == dir)
+    }
+
+    @Test func resolveSafeCwdNeverReturnsNil() {
+        let missing = URL(fileURLWithPath: "/nonexistent-\(UUID().uuidString)")
+        let resolved = PathSecurity.resolveSafeCwd(missing)
+        #expect(FileManager.default.fileExists(atPath: resolved.path))
+    }
+}
+
+@Suite("AtomicFileWriter")
+struct AtomicFileWriterTests {
+    @Test func writesAndLeavesNoTmp() throws {
+        let dir = try tempDir()
+        let url = dir.appendingPathComponent("state.json")
+        try AtomicFileWriter.write(Data("{\"a\":1}".utf8), to: url)
+        #expect(try String(contentsOf: url, encoding: .utf8) == "{\"a\":1}")
+        #expect(!FileManager.default.fileExists(atPath: url.appendingPathExtension("tmp").path))
+    }
+
+    @Test func overwritesExistingAtomically() throws {
+        let dir = try tempDir()
+        let url = dir.appendingPathComponent("f.txt")
+        try AtomicFileWriter.write("one", to: url)
+        try AtomicFileWriter.write("two-longer", to: url)
+        #expect(try String(contentsOf: url, encoding: .utf8) == "two-longer")
+    }
+
+    @Test func createsParentDirs() throws {
+        let dir = try tempDir()
+        let url = dir.appendingPathComponent("a/b/c/deep.json")
+        try AtomicFileWriter.write("{}", to: url)
+        #expect(FileManager.default.fileExists(atPath: url.path))
+    }
+}
+
+@Suite("ArtefactProbe")
+struct ArtefactProbeTests {
+    @Test func verifyProgression() throws {
+        let dir = try tempDir()
+        var v = ArtefactProbe.verify(basename: "t", cwd: dir)
+        #expect(v == StageArtefacts())
+
+        try touch(dir.appendingPathComponent("t.ti1"))
+        v = ArtefactProbe.verify(basename: "t", cwd: dir)
+        #expect(v.stage1Complete && !v.stage2Complete && !v.stage3Complete)
+
+        try touch(dir.appendingPathComponent("t.ti2"))
+        try touch(dir.appendingPathComponent("t.ti3"))
+        v = ArtefactProbe.verify(basename: "t", cwd: dir)
+        #expect(v.stage2Complete && v.stage3Complete && !v.stage4Complete)
+
+        try touch(dir.appendingPathComponent("t.icc"))
+        v = ArtefactProbe.verify(basename: "t", cwd: dir)
+        #expect(v.stage4Complete && v.profilePath?.pathExtension == "icc")
+    }
+
+    @Test func icmWinsOverIcc() throws {
+        let dir = try tempDir()
+        try touch(dir.appendingPathComponent("p.icc"))
+        try touch(dir.appendingPathComponent("p.icm"))
+        let profile = ArtefactProbe.resolveProfile(basename: "p", cwd: dir)
+        #expect(profile?.pathExtension == "icm")
+    }
+
+    @Test func enumeratesPassesPagesAndCAL() throws {
+        let dir = try tempDir()
+        for name in [
+            "t.ti1", "t.ti2", "t.tif", "t.2.tif", "t_03.tif",
+            "t.ti3", "t_pass1.ti3", "t_pass2.ti3",
+            "t.icc", "t.gam",
+            "CAL_t.ti1", "CAL_t.cal",
+            // must NOT match:
+            "other.ti1", "t.txt", "CAL_other.ti1",
+        ] { try touch(dir.appendingPathComponent(name)) }
+
+        let names = ArtefactProbe.existingArtefacts(basename: "t", cwd: dir)
+            .map(\.lastPathComponent)
+        for expected in [
+            "t.ti1", "t.ti2", "t.tif", "t.2.tif", "t_03.tif",
+            "t.ti3", "t_pass1.ti3", "t_pass2.ti3",
+            "t.icc", "t.gam", "CAL_t.ti1", "CAL_t.cal",
+        ] {
+            #expect(names.contains(expected), "missing \(expected)")
+        }
+        #expect(!names.contains("other.ti1"))
+        #expect(!names.contains("t.txt"))
+        #expect(!names.contains("CAL_other.ti1"))
+    }
+
+    @Test func emptyDirReturnsEmpty() throws {
+        let dir = try tempDir()
+        #expect(ArtefactProbe.existingArtefacts(basename: "x", cwd: dir).isEmpty)
+    }
+}

Tests/ICCeryCoreTests/SettingsTests.swift

@@ -0,0 +1,164 @@
+import Testing
+import Foundation
+@testable import ICCeryCore
+
+private func tempStoreURL() -> URL {
+    FileManager.default.temporaryDirectory
+        .appendingPathComponent("iccery-settings-\(UUID().uuidString)")
+        .appendingPathComponent("settings.json")
+}
+
+@Suite("AppSettings")
+struct AppSettingsTests {
+    @Test func defaults() {
+        let s = AppSettings.default
+        #expect(s.argyllBinaryDir == nil)
+        #expect(s.defaultInstrument == nil)
+        #expect(s.logLevel == nil)
+        #expect(s.deltaEGoodMax == 2.0)
+        #expect(s.deltaEWarningMax == 5.0)
+        #expect(s.customPresets.isEmpty)
+        #expect(!s.enableI1Pro2Leds)
+        #expect(s.calibrationStaleDays == 30)
+        #expect(s.defaultInstallLocation == .user)
+        #expect(s.askBeforeOverwriteProfile)
+        #expect(!s.openColorPanelAfterInstall)
+        #expect(s.isValid)
+    }
+
+    @Test func negativeThresholds() {
+        var s = AppSettings.default
+        s.deltaEGoodMax = -1
+        #expect(s.validate() == [AppSettings.errorNegativeDeltaE])
+        s.deltaEGoodMax = 2.0
+        s.deltaEWarningMax = -0.5
+        // -0.5 < 0 → negative error; good(2.0) >= warn(-0.5) → order error too
+        #expect(s.validate() == [
+            AppSettings.errorNegativeDeltaE,
+            AppSettings.errorThresholdOrder,
+        ])
+    }
+
+    @Test func goodMustBeStrictlyLessThanWarning() {
+        var s = AppSettings.default
+        s.deltaEGoodMax = 5.0
+        #expect(s.validate() == [AppSettings.errorThresholdOrder])
+        s.deltaEGoodMax = 6.0
+        #expect(s.validate() == [AppSettings.errorThresholdOrder])
+        s.deltaEGoodMax = 4.9
+        #expect(s.isValid)
+    }
+
+    @Test func snakeCaseKeys() throws {
+        let s = AppSettings.default
+        let data = try JSONEncoder().encode(s)
+        let json = String(data: data, encoding: .utf8)!
+        #expect(json.contains("\"delta_e_good_max\""))
+        #expect(json.contains("\"default_install_location\""))
+        #expect(json.contains("\"enable_i1pro2_leds\""))
+    }
+}
+
+@Suite("SettingsStore")
+struct SettingsStoreTests {
+    @Test func roundTrip() throws {
+        let url = tempStoreURL()
+        let store = SettingsStore(fileURL: url)
+        var s = AppSettings.default
+        s.deltaEGoodMax = 1.5
+        s.defaultInstrument = "p3"
+        try store.save(s)
+        #expect(store.load() == s)
+    }
+
+    @Test func corruptJsonFallsBackToDefaults() throws {
+        let url = tempStoreURL()
+        try FileManager.default.createDirectory(
+            at: url.deletingLastPathComponent(), withIntermediateDirectories: true
+        )
+        try "{ not json".write(to: url, atomically: true, encoding: .utf8)
+        #expect(SettingsStore(fileURL: url).load() == .default)
+    }
+
+    @Test func missingFileReturnsDefaults() {
+        #expect(SettingsStore(fileURL: tempStoreURL()).load() == .default)
+    }
+
+    @Test func invalidSettingsNotPersisted() throws {
+        let url = tempStoreURL()
+        let store = SettingsStore(fileURL: url)
+        var s = AppSettings.default
+        s.deltaEGoodMax = 9.0 // >= warning 5.0
+        #expect(throws: SettingsStore.SettingsError.self) { try store.save(s) }
+        #expect(!FileManager.default.fileExists(atPath: url.path))
+    }
+
+    @Test func savePostsNotification() async throws {
+        let url = tempStoreURL()
+        let store = SettingsStore(fileURL: url)
+        var fired = false
+        let token = NotificationCenter.default.addObserver(
+            forName: SettingsStore.settingsDidChange, object: nil, queue: nil
+        ) { _ in fired = true }
+        defer { NotificationCenter.default.removeObserver(token) }
+        try store.save(.default)
+        #expect(fired)
+    }
+}
+
+@Suite("LogSink")
+struct LogSinkTests {
+    private func tempLog() -> (URL, LogSink) {
+        let url = FileManager.default.temporaryDirectory
+            .appendingPathComponent("iccery-log-\(UUID().uuidString)")
+            .appendingPathComponent("iccery.log")
+        return (url, LogSink(fileURL: url))
+    }
+
+    @Test func writesFormattedLines() {
+        let (url, sink) = tempLog()
+        sink.setLevel(.debug)
+        sink.write(level: .info, category: "test", message: "hello")
+        let content = (try? String(contentsOf: url, encoding: .utf8)) ?? ""
+        #expect(content.contains("[INFO] test: hello"))
+    }
+
+    @Test func levelFilteringIsLive() {
+        let (url, sink) = tempLog()
+        sink.setLevel(.error)
+        sink.write(level: .info, category: "t", message: "hidden")
+        sink.setLevel(.info)   // runtime change, no restart (#158)
+        sink.write(level: .info, category: "t", message: "shown")
+        let content = (try? String(contentsOf: url, encoding: .utf8)) ?? ""
+        #expect(!content.contains("hidden"))
+        #expect(content.contains("shown"))
+    }
+
+    @Test func rotatesAt5MiBKeeping5Segments() throws {
+        let (url, sink) = tempLog()
+        sink.setLevel(.trace)
+        // Pre-fill the active log just under the cap, then cross it.
+        try FileManager.default.createDirectory(
+            at: url.deletingLastPathComponent(), withIntermediateDirectories: true
+        )
+        let big = String(repeating: "x", count: Int(LogSink.maxSegmentBytes))
+        try big.write(to: url, atomically: true, encoding: .utf8)
+
+        sink.write(level: .info, category: "t", message: "trigger rotation")
+        #expect(FileManager.default.fileExists(
+            atPath: url.appendingPathExtension("1").path
+        ))
+        // Active log is small again.
+        let size = try FileManager.default.attributesOfItem(
+            atPath: url.path
+        )[.size] as? UInt64
+        #expect((size ?? 0) < 1024)
+    }
+
+    @Test func tailExcerptCaps() throws {
+        let (url, sink) = tempLog()
+        sink.setLevel(.debug)
+        sink.write(level: .info, category: "t", message: "line")
+        #expect(sink.tailExcerpt(maxBytes: 8).count <= 8)
+    }
+}

Tests/ICCeryCoreTests/WizardGatingTests.swift

@@ -0,0 +1,127 @@
+import Testing
+import Foundation
+@testable import ICCeryCore
+
+private func artefacts(
+    ti1: Bool = false, ti2: Bool = false, ti3: Bool = false, profile: Bool = false
+) -> StageArtefacts {
+    var a = StageArtefacts()
+    a.stage1Complete = ti1
+    a.stage2Complete = ti2
+    a.stage3Complete = ti3
+    a.stage4Complete = profile
+    if profile {
+        a.profilePath = URL(fileURLWithPath: "/x/t.icc")
+    }
+    return a
+}
+
+@Suite("WizardGating matrix")
+struct WizardGatingTests {
+
+    @Test func emptyProjectOnlyStage1() {
+        let a = artefacts()
+        #expect(WizardGating.isUnlocked(.generate, artefacts: a))
+        #expect(WizardGating.isUnlocked(.calibrate, artefacts: a))
+        for s in [WizardStage.layOutPrint, .measure, .buildProfile, .verifyInstall] {
+            #expect(!WizardGating.isUnlocked(s, artefacts: a), "\(s) should be locked")
+        }
+    }
+
+    @Test func ti1UnlocksStage2Only() {
+        let a = artefacts(ti1: true)
+        #expect(WizardGating.isUnlocked(.layOutPrint, artefacts: a))
+        #expect(!WizardGating.isUnlocked(.measure, artefacts: a))
+        #expect(!WizardGating.isUnlocked(.buildProfile, artefacts: a))
+        #expect(!WizardGating.isUnlocked(.verifyInstall, artefacts: a))
+    }
+
+    @Test func stage3NeedsTi1AndTi2() {
+        #expect(!WizardGating.isUnlocked(.measure, artefacts: artefacts(ti2: true)))
+        #expect(WizardGating.isUnlocked(.measure, artefacts: artefacts(ti1: true, ti2: true)))
+    }
+
+    @Test func stage4NeedsTi3NotTi2() {
+        // #109/#110: .ti2 alone must never unlock Stage 4.
+        let a = artefacts(ti1: true, ti2: true)
+        #expect(!WizardGating.isUnlocked(.buildProfile, artefacts: a))
+        #expect(WizardGating.isUnlocked(.buildProfile, artefacts: artefacts(ti3: true)))
+    }
+
+    @Test func stage5NeedsTi3AndProfile() {
+        #expect(!WizardGating.isUnlocked(.verifyInstall, artefacts: artefacts(ti3: true)))
+        #expect(!WizardGating.isUnlocked(.verifyInstall, artefacts: artefacts(profile: true)))
+        #expect(WizardGating.isUnlocked(
+            .verifyInstall, artefacts: artefacts(ti3: true, profile: true)
+        ))
+    }
+
+    @Test func forwardGatedBackwardFree() {
+        let a = artefacts()
+        #expect(!WizardGating.canNavigate(to: .layOutPrint, from: .generate, artefacts: a))
+        // Backward always allowed even when artefacts vanished.
+        #expect(WizardGating.canNavigate(to: .generate, from: .measure, artefacts: a))
+        // Same stage is a no-op.
+        #expect(WizardGating.canNavigate(to: .measure, from: .measure, artefacts: a))
+        // Stage 0 is a side-trip, never gated.
+        #expect(WizardGating.canNavigate(to: .calibrate, from: .generate, artefacts: a))
+    }
+
+    @Test func deepestUnlocked() {
+        #expect(WizardGating.deepestUnlocked(artefacts: artefacts()) == .generate)
+        #expect(WizardGating.deepestUnlocked(
+            artefacts: artefacts(ti1: true, ti2: true)
+        ) == .measure)
+        #expect(WizardGating.deepestUnlocked(
+            artefacts: artefacts(ti3: true, profile: true)
+        ) == .verifyInstall)
+    }
+}
+
+@Suite("WizardStateStore")
+struct WizardStateStoreTests {
+    private func tempURL() -> URL {
+        FileManager.default.temporaryDirectory
+            .appendingPathComponent("iccery-wiz-\(UUID().uuidString)")
+            .appendingPathComponent("wizard_state.json")
+    }
+
+    @Test func roundTrip() throws {
+        let url = tempURL()
+        let store = WizardStateStore(fileURL: url)
+        var s = WizardState()
+        s.currentStage = 3
+        s.basename = "run-42"
+        s.cwd = "/tmp/charts"
+        s.sessionMode = .calibration
+        s.profileBasename = "imported"
+        try store.save(s)
+        #expect(store.load() == s)
+    }
+
+    @Test func missingFileDefaults() {
+        let s = WizardStateStore(fileURL: tempURL()).load()
+        #expect(s == .default)
+        #expect(s.stage == .generate)
+        #expect(s.sessionMode == .profile)
+    }
+
+    @Test func corruptStageFallsBackToGenerate() throws {
+        let url = tempURL()
+        try FileManager.default.createDirectory(
+            at: url.deletingLastPathComponent(), withIntermediateDirectories: true
+        )
+        try #"{"current_stage": 99, "basename": "", "cwd": "", "session_mode": "profile"}"#
+            .write(to: url, atomically: true, encoding: .utf8)
+        #expect(WizardStateStore(fileURL: url).load().stage == .generate)
+    }
+
+    @Test func sessionModeCalibrationRoundTrips() throws {
+        var s = WizardState(sessionMode: .calibration)
+        let data = try JSONEncoder().encode(s)
+        let decoded = try JSONDecoder().decode(WizardState.self, from: data)
+        #expect(decoded.sessionMode == .calibration)
+        s.sessionMode = .profile
+        #expect(s.sessionMode == .profile)
+    }
+}

project.yml

@@ -19,9 +19,25 @@ targets:
       - path: Resources
         excludes:
           - ICCery.entitlements
+          - Argyll
+      - path: Resources/Argyll
+        type: folder
     dependencies:
       - package: ICCeryCore
         product: ICCeryCore
+    postBuildScripts:
+      - name: Copy Argyll sidecars
+        script: |
+          set -e
+          SRC="${SRCROOT}/Vendor/Argyll"
+          DEST="${BUILT_PRODUCTS_DIR}/${UNLOCALIZED_RESOURCES_FOLDER_PATH}/Argyll"
+          if [ -d "$SRC" ]; then
+            mkdir -p "$DEST"
+            rsync -a "$SRC/" "$DEST/"
+          else
+            echo "note: Vendor/Argyll absent — run scripts/fetch-argyll.sh"
+          fi
+        basedOnDependencyAnalysis: false
     settings:
       base:
         PRODUCT_BUNDLE_IDENTIFIER: com.gronod.iccery2

scripts/fetch-argyll.sh

@@ -0,0 +1,140 @@
+#!/bin/sh
+# scripts/fetch-argyll.sh
+#
+# Downloads the Gronod ArgyllCMS fork release (macOS universal binaries)
+# into Vendor/Argyll/. POSIX sh + curl + tar — no Node dependency.
+#
+# Env overrides (parity with v1 fetch-argyll.mjs):
+#   ARGYLL_SERVER_URL   default https://git.i3omb.com
+#   ARGYLL_REPO         default gronod/argyllcms
+#   ARGYLL_RELEASE_TAG   default: latest release
+#   GITEA_TOKEN         optional, for private repos
+#
+# Layout produced (docs/04 §0.6, docs/02 §Sidecar layout):
+#   Vendor/Argyll/macos-universal/<tools>   # marker binary: instlist
+# Mocks and reference_gamuts are tracked under Resources/Argyll/ —
+# they ship in git, not in the release tarball.
+
+set -eu
+
+SERVER="${ARGYLL_SERVER_URL:-https://git.i3omb.com}"
+REPO="${ARGYLL_REPO:-gronod/argyllcms}"
+TAG="${ARGYLL_RELEASE_TAG:-}"
+SUFFIX="_macOS_universal_bin.tgz"
+PLATFORM_DIR="macos-universal"
+MARKER="instlist"
+
+ROOT="$(CDPATH='' cd -- "$(dirname -- "$0")/.." && pwd)"
+DEST="$ROOT/Vendor/Argyll/$PLATFORM_DIR"
+
+FORCE=0
+for arg in "$@"; do
+    case "$arg" in
+        --force) FORCE=1 ;;
+        *) echo "usage: $0 [--force]" >&2; exit 2 ;;
+    esac
+done
+
+if [ "$FORCE" -eq 0 ] && [ -x "$DEST/$MARKER" ]; then
+    echo "ArgyllCMS binaries already present at $DEST (use --force to re-download)"
+    exit 0
+fi
+
+AUTH_HEADER=""
+if [ -n "${GITEA_TOKEN:-}" ]; then
+    AUTH_HEADER="Authorization: token $GITEA_TOKEN"
+fi
+
+api_get() {
+    if [ -n "$AUTH_HEADER" ]; then
+        curl -fsSL -H 'Accept: application/json' -H "$AUTH_HEADER" "$1"
+    else
+        curl -fsSL -H 'Accept: application/json' "$1"
+    fi
+}
+
+if [ -n "$TAG" ]; then
+    API_URL="$SERVER/api/v1/repos/$REPO/releases/tags/$TAG"
+else
+    API_URL="$SERVER/api/v1/repos/$REPO/releases/latest"
+fi
+
+echo "Fetching release info from $API_URL"
+RELEASE_JSON="$(api_get "$API_URL")" || {
+    echo "error: failed to fetch release info (set GITEA_TOKEN if the repo is private)" >&2
+    exit 1
+}
+
+# Find the macOS universal asset's browser_download_url without jq.
+ASSET_URL="$(printf '%s' "$RELEASE_JSON" \
+    | tr ',' '\n' \
+    | grep '"browser_download_url"' \
+    | grep "$SUFFIX" \
+    | sed -E 's/.*"browser_download_url"[^"]*"([^"]+)".*/\1/' \
+    | head -n 1)"
+
+if [ -z "$ASSET_URL" ]; then
+    echo "error: no release asset matching '*$SUFFIX' on $API_URL" >&2
+    echo "looked-for pattern: Argyll_<tag>_<sha>$SUFFIX" >&2
+    exit 1
+fi
+
+echo "Downloading $ASSET_URL"
+TMPDIR_FETCH="$(mktemp -d)"
+trap 'rm -rf "$TMPDIR_FETCH"' EXIT
+ARCHIVE="$TMPDIR_FETCH/argyll.tgz"
+
+if [ -n "$AUTH_HEADER" ]; then
+    curl -fSL -o "$ARCHIVE" -H "$AUTH_HEADER" "$ASSET_URL"
+else
+    curl -fSL -o "$ARCHIVE" "$ASSET_URL"
+fi
+
+EXTRACT="$TMPDIR_FETCH/extract"
+mkdir -p "$EXTRACT"
+tar -xzf "$ARCHIVE" -C "$EXTRACT"
+
+# Archive contains Argyll_V*/bin/ (or a bare bin/).
+BIN_DIR=""
+for d in "$EXTRACT"/Argyll_V*/bin "$EXTRACT"/bin; do
+    if [ -d "$d" ]; then BIN_DIR="$d"; break; fi
+done
+if [ -z "$BIN_DIR" ]; then
+    echo "error: archive has no Argyll_V*/bin or bin/ directory" >&2
+    exit 1
+fi
+
+mkdir -p "$DEST"
+cp -R "$BIN_DIR"/. "$DEST"/
+find "$DEST" -type f -exec chmod 0755 {} +
+# Downloads carry com.apple.quarantine; the app cannot spawn quarantined tools.
+xattr -dr com.apple.quarantine "$DEST" 2>/dev/null || true
+
+# Ad-hoc sign every Mach-O (#165: unsigned arm64 → "Killed: 9"), then
+# verify — an unsigned sidecar fails the script.
+for f in "$DEST"/*; do
+    [ -f "$f" ] || continue
+    if file -b "$f" | grep -q 'Mach-O'; then
+        codesign -f -s - "$f" 2>/dev/null || true
+    fi
+done
+UNSIGNED=""
+for f in "$DEST"/*; do
+    [ -f "$f" ] || continue
+    if file -b "$f" | grep -q 'Mach-O'; then
+        if ! codesign -dvv "$f" >/dev/null 2>&1; then
+            UNSIGNED="$UNSIGNED $f"
+        fi
+    fi
+done
+if [ -n "$UNSIGNED" ]; then
+    echo "error: unsigned binaries remain:$UNSIGNED" >&2
+    exit 1
+fi
+
+if [ ! -x "$DEST/$MARKER" ]; then
+    echo "error: marker binary $MARKER missing after extraction" >&2
+    exit 1
+fi
+
+echo "OK: $(ls "$DEST" | wc -l | tr -d ' ') tools installed to $DEST"