Real grammar engine + scan every text area on screen

- SystemGrammarEngine: on-device spelling + grammar via NSSpellChecker (no deps,
  no network), augmented with deterministic Harper-style rules. Now the default.
- TextFieldScanner: walks the frontmost window's Accessibility tree to find every
  editable text area (bounded for huge web/Electron trees), not just the focused one.
- LiveMonitor now publishes per-field issues across the whole window + fix methods
  (apply one suggestion, fix a field, fix everything) via AX value writes.
- LiveCheckView: a panel listing each text area with errors highlighted inline and
  one-click fixes; opened from the menu bar (Show live issues / Show issues / Fix all).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Sources/GrammaGem/App/AppState.swift

@@ -39,11 +39,12 @@ final class AppState: ObservableObject {
     private var onboardingWindow: NSWindow?
     private var askWindow: NSWindow?
     private var mainWindow: NSWindow?
+    private var liveCheckWindow: NSWindow?
     private var cancellables = Set<AnyCancellable>()
 
     private init() {
-        let harper = HarperEngine()
-        grammar = harper
+        let engine = SystemGrammarEngine()
+        grammar = engine
         ai = MLXEngine(ready: true)
         permissions = Permissions()
         model = ModelManager()
@@ -59,9 +60,9 @@ final class AppState: ObservableObject {
         snippets = SnippetStore()
         let excl = Exclusions()
         exclusions = excl
-        liveMonitor = LiveMonitor(grammar: harper, detector: detector, exclusions: excl, capture: capture)
+        liveMonitor = LiveMonitor(grammar: engine, detector: detector, exclusions: excl, capture: capture)
         coordinator = TextReplacementCoordinator(
-            capture: capture, grammar: harper, ai: ai, gate: gate, detector: detector)
+            capture: capture, grammar: engine, ai: ai, gate: gate, detector: detector)
     }
 
     /// Called once at launch (from the AppDelegate).
@@ -140,6 +141,27 @@ final class AppState: ObservableObject {
         liveMonitor.refreshSoon()
     }
 
+    // MARK: - Live multi-field fixes (from the Live Check panel)
+
+    func fixAllDetected() {
+        if let reason = blockReason() { lastStatus = reason; return }
+        let n = liveMonitor.fixAll()
+        if n > 0 { usage.recordCorrection(words: n) }
+        lastStatus = n > 0 ? "Fixed \(n) issue\(n == 1 ? "" : "s")" : "Nothing to fix"
+    }
+
+    func fixDetectedField(_ field: DetectedField) {
+        if let reason = blockReason() { lastStatus = reason; return }
+        let n = liveMonitor.fix(field)
+        if n > 0 { usage.recordCorrection(words: n) }
+    }
+
+    func applySuggestion(_ suggestion: Suggestion, in field: DetectedField) {
+        if let reason = blockReason() { lastStatus = reason; return }
+        liveMonitor.apply(suggestion, in: field)
+        usage.recordCorrection(words: 1)
+    }
+
     /// Pause/resume all of GrammaGem (hotkeys + live monitoring).
     func togglePause() {
         isPaused.toggle()
@@ -258,6 +280,27 @@ final class AppState: ObservableObject {
         mainWindow?.makeKeyAndOrderFront(nil)
     }
 
+    /// The Live Check panel: every on-screen text area with grammar issues.
+    func showLiveCheck() {
+        if liveCheckWindow == nil {
+            let root = LiveCheckView()
+                .environmentObject(self)
+                .environmentObject(liveMonitor)
+            let host = NSHostingController(rootView: root)
+            let win = NSWindow(contentViewController: host)
+            win.title = "Live Check"
+            win.styleMask = [.titled, .closable, .miniaturizable, .resizable]
+            win.setContentSize(NSSize(width: 560, height: 620))
+            win.minSize = NSSize(width: 460, height: 420)
+            win.isReleasedWhenClosed = false
+            win.center()
+            liveCheckWindow = win
+        }
+        liveMonitor.refreshSoon()
+        NSApp.activate(ignoringOtherApps: true)
+        liveCheckWindow?.makeKeyAndOrderFront(nil)
+    }
+
     func showAsk() {
         askText = ""
         if askWindow == nil {

Sources/GrammaGem/App/MainWindow/LiveCheckView.swift

@@ -0,0 +1,169 @@
+import SwiftUI
+import AppKit
+
+/// A floating panel that lists every on-screen text area with grammar/spelling
+/// issues, shows the offending text with the errors highlighted, and offers
+/// one-click fixes (per issue, per field, or everything).
+struct LiveCheckView: View {
+    @EnvironmentObject private var app: AppState
+    @ObservedObject private var monitor: LiveMonitor
+
+    init() {
+        _monitor = ObservedObject(wrappedValue: AppState.shared.liveMonitor)
+    }
+
+    var body: some View {
+        VStack(spacing: 0) {
+            header
+            Divider()
+            if monitor.fields.isEmpty {
+                emptyState
+            } else {
+                ScrollView {
+                    VStack(spacing: 14) {
+                        ForEach(monitor.fields) { field in
+                            FieldCard(field: field)
+                        }
+                    }
+                    .padding(16)
+                }
+            }
+        }
+        .frame(maxWidth: .infinity, maxHeight: .infinity)
+        .tint(GG.emerald)
+    }
+
+    private var header: some View {
+        HStack(spacing: 12) {
+            VStack(alignment: .leading, spacing: 2) {
+                Text(summary).font(.headline)
+                Text(monitor.activeAppName.isEmpty
+                     ? "Checking text areas on screen"
+                     : "In \(monitor.activeAppName) · \(monitor.scannedCount) text area\(monitor.scannedCount == 1 ? "" : "s") checked")
+                    .font(.caption).foregroundStyle(.secondary)
+            }
+            Spacer()
+            Button { monitor.refreshSoon() } label: { Image(systemName: "arrow.clockwise") }
+                .help("Re-scan now")
+            if monitor.issueCount > 0 {
+                Button { app.fixAllDetected() } label: {
+                    Label("Fix everything", systemImage: "checkmark.circle.fill")
+                }
+                .buttonStyle(.borderedProminent)
+            }
+        }
+        .padding(16)
+    }
+
+    private var summary: String {
+        let issues = monitor.issueCount
+        if issues == 0 { return "No issues found" }
+        return "\(issues) issue\(issues == 1 ? "" : "s") across \(monitor.fields.count) text area\(monitor.fields.count == 1 ? "" : "s")"
+    }
+
+    private var emptyState: some View {
+        VStack(spacing: 10) {
+            Image(systemName: "checkmark.seal.fill").font(.system(size: 42)).foregroundStyle(GG.emerald)
+            Text("Looks clean").font(.title3.weight(.semibold))
+            Text("No grammar or spelling issues in the text on screen right now.")
+                .font(.callout).foregroundStyle(.secondary).multilineTextAlignment(.center)
+        }
+        .frame(maxWidth: .infinity, maxHeight: .infinity)
+        .padding(40)
+    }
+}
+
+/// One detected text area: highlighted text + its individual issues.
+private struct FieldCard: View {
+    @EnvironmentObject private var app: AppState
+    let field: DetectedField
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 10) {
+            HStack(spacing: 8) {
+                Image(systemName: field.isFocused ? "cursorarrow.rays" : "text.cursor")
+                    .foregroundStyle(field.isFocused ? GG.emerald : .secondary)
+                Text(field.label).font(.subheadline.weight(.semibold)).lineLimit(1)
+                Text(field.roleName).font(.caption).foregroundStyle(.secondary)
+                Spacer()
+                Text("\(field.suggestions.count)")
+                    .font(.caption.weight(.semibold))
+                    .padding(.horizontal, 7).padding(.vertical, 2)
+                    .background(GG.gold.opacity(0.2), in: Capsule())
+                    .foregroundStyle(GG.gold)
+            }
+
+            Text(highlighted(field.text, field.suggestions))
+                .font(.callout)
+                .textSelection(.enabled)
+                .frame(maxWidth: .infinity, alignment: .leading)
+                .padding(10)
+                .background(Color(nsColor: .textBackgroundColor), in: RoundedRectangle(cornerRadius: 8))
+
+            VStack(spacing: 6) {
+                ForEach(field.suggestions) { s in
+                    HStack(spacing: 8) {
+                        Circle().fill(color(for: s.kind)).frame(width: 7, height: 7)
+                        VStack(alignment: .leading, spacing: 1) {
+                            Text(s.message).font(.caption)
+                            if s.replacement != s.original && !s.replacement.isEmpty {
+                                Text("“\(s.original)” → “\(s.replacement)”")
+                                    .font(.caption2.monospaced()).foregroundStyle(.secondary).lineLimit(1)
+                            }
+                        }
+                        Spacer()
+                        if s.replacement != s.original && !s.replacement.isEmpty {
+                            Button("Apply") { app.applySuggestion(s, in: field) }
+                                .controlSize(.small)
+                        }
+                    }
+                }
+            }
+
+            HStack {
+                Spacer()
+                Button { app.fixDetectedField(field) } label: {
+                    Label("Fix this field", systemImage: "checkmark.circle")
+                }
+                .controlSize(.small)
+            }
+        }
+        .padding(14)
+        .background(Color(nsColor: .controlBackgroundColor), in: RoundedRectangle(cornerRadius: 12))
+        .overlay(RoundedRectangle(cornerRadius: 12).stroke(Color.primary.opacity(0.07)))
+    }
+
+    private func color(for kind: GrammarKind) -> Color {
+        switch kind {
+        case .spelling: return .red
+        case .grammar, .punctuation: return .orange
+        default: return GG.gold
+        }
+    }
+
+    /// Build an attributed string with each issue span tinted.
+    private func highlighted(_ text: String, _ suggestions: [Suggestion]) -> AttributedString {
+        let ns = text as NSString
+        let sorted = suggestions.sorted { $0.location < $1.location }
+        var result = AttributedString()
+        var cursor = 0
+        for s in sorted {
+            let loc = s.location, len = s.length
+            guard loc >= cursor, len > 0, loc + len <= ns.length else { continue }
+            if loc > cursor {
+                result += AttributedString(ns.substring(with: NSRange(location: cursor, length: loc - cursor)))
+            }
+            var run = AttributedString(ns.substring(with: NSRange(location: loc, length: len)))
+            let tint: Color = s.kind == .spelling ? .red : .orange
+            run.backgroundColor = tint.opacity(0.18)
+            run.foregroundColor = tint
+            run.underlineStyle = .single
+            result += run
+            cursor = loc + len
+        }
+        if cursor < ns.length {
+            result += AttributedString(ns.substring(with: NSRange(location: cursor, length: ns.length - cursor)))
+        }
+        return result
+    }
+}

Sources/GrammaGem/App/MenuBarContent.swift

@@ -57,6 +57,7 @@ struct MenuBarContent: View {
 
             Divider()
 
+            actionRow(title: "Show live issues…", shortcut: nil) { app.showLiveCheck() }
             actionRow(title: "Open GrammaGem…", shortcut: nil) { app.showMainWindow() }
             actionRow(title: "Manage devices…", shortcut: nil) { app.showMainWindow(select: .devices) }
             actionRow(title: "Page blocker…", shortcut: nil) { app.showMainWindow(select: .exclusions) }
@@ -102,24 +103,31 @@ struct MenuBarContent: View {
 
     @ViewBuilder
     private var liveStatus: some View {
+        let inApp = monitor.activeAppName.isEmpty ? "" : " in \(monitor.activeAppName)"
         if app.isPaused {
             Label("Paused — not monitoring", systemImage: "pause.circle")
                 .font(.callout).foregroundStyle(.secondary)
         } else if monitor.issueCount > 0 {
             VStack(alignment: .leading, spacing: 6) {
-                Label("\(monitor.issueCount) suggestion\(monitor.issueCount == 1 ? "" : "s")"
-                      + (monitor.activeAppName.isEmpty ? "" : " in \(monitor.activeAppName)"),
-                      systemImage: "text.badge.checkmark")
+                Label("\(monitor.issueCount) issue\(monitor.issueCount == 1 ? "" : "s") in "
+                      + "\(monitor.fields.count) text area\(monitor.fields.count == 1 ? "" : "s")" + inApp,
+                      systemImage: "text.badge.xmark")
                     .font(.callout).foregroundStyle(.primary)
-                ForEach(monitor.suggestions.prefix(3)) { s in
-                    Text("• \(s.message): “\(s.original)” → “\(s.replacement)”")
+                ForEach(monitor.fields.prefix(2)) { f in
+                    Text("• \(f.label): \(f.suggestions.count) issue\(f.suggestions.count == 1 ? "" : "s")")
                         .font(.caption).foregroundStyle(.secondary).lineLimit(1)
                 }
-                Button { Task { await app.fixFocusedField() } } label: {
+                HStack {
+                    Button { app.showLiveCheck() } label: {
+                        Label("Show issues", systemImage: "list.bullet.rectangle")
+                    }
+                    .controlSize(.small)
+                    Button { app.fixAllDetected() } label: {
                         Label("Fix all", systemImage: "checkmark.circle.fill")
                     }
                     .buttonStyle(.borderedProminent).controlSize(.small)
                 }
+            }
         } else if monitor.running {
             Label(monitor.activeAppName.isEmpty ? "Monitoring — looks clean"
                   : "Watching \(monitor.activeAppName) — looks clean",

Sources/GrammaGem/Grammar/SystemGrammarEngine.swift

@@ -0,0 +1,93 @@
+import Foundation
+import AppKit
+
+/// Real, on-device grammar + spelling using macOS's built-in `NSSpellChecker`
+/// (the same engine TextEdit/Mail use). No network, no model — fully local,
+/// matching the privacy promise. Augmented with a few deterministic Harper-style
+/// rules (repeated words, lowercase "i", common expansions) the system checker
+/// doesn't surface.
+final class SystemGrammarEngine: GrammarEngine {
+    var ignoreList: Set<String> = []
+
+    private let checker = NSSpellChecker.shared
+    private let tag = NSSpellChecker.uniqueSpellDocumentTag()
+    private let extras = HarperEngine()
+
+    func check(_ text: String) -> [Suggestion] {
+        guard text.count >= 2 else { return [] }
+        return onMain { self.checkOnMain(text) }
+    }
+
+    private func checkOnMain(_ text: String) -> [Suggestion] {
+        let ns = text as NSString
+        let full = NSRange(location: 0, length: ns.length)
+        let language = checker.language()
+        var out: [Suggestion] = []
+
+        let types = NSTextCheckingResult.CheckingType([.spelling, .grammar]).rawValue
+        let results = checker.check(
+            text, range: full, types: types, options: nil,
+            inSpellDocumentWithTag: tag, orthography: nil, wordCount: nil)
+
+        for r in results {
+            switch r.resultType {
+            case .spelling:
+                let word = ns.substring(with: r.range)
+                if ignoreList.contains(word.lowercased()) { continue }
+                let fix = checker.correction(
+                    forWordRange: r.range, in: text, language: language, inSpellDocumentWithTag: tag)
+                    ?? checker.guesses(
+                        forWordRange: r.range, in: text, language: language,
+                        inSpellDocumentWithTag: tag)?.first
+                out.append(Suggestion(
+                    location: r.range.location, length: r.range.length,
+                    original: word, replacement: fix ?? word,
+                    kind: .spelling, message: "Possible spelling mistake"))
+
+            case .grammar:
+                let details = r.grammarDetails ?? []
+                if details.isEmpty {
+                    let phrase = ns.substring(with: r.range)
+                    out.append(Suggestion(
+                        location: r.range.location, length: r.range.length,
+                        original: phrase, replacement: phrase,
+                        kind: .grammar, message: "Grammar issue"))
+                } else {
+                    for d in details {
+                        var loc = r.range.location, len = r.range.length
+                        if let rv = d[NSGrammarRange] as? NSValue {
+                            let sub = rv.rangeValue
+                            loc = r.range.location + sub.location
+                            len = sub.length
+                        }
+                        guard len > 0, loc + len <= ns.length else { continue }
+                        let phrase = ns.substring(with: NSRange(location: loc, length: len))
+                        let message = (d[NSGrammarUserDescription] as? String) ?? "Grammar issue"
+                        let corrections = (d[NSGrammarCorrections] as? [String]) ?? []
+                        out.append(Suggestion(
+                            location: loc, length: len,
+                            original: phrase, replacement: corrections.first ?? phrase,
+                            kind: .grammar, message: message))
+                    }
+                }
+            default:
+                break
+            }
+        }
+
+        // Deterministic extras, skipping anything overlapping a system result.
+        extras.ignoreList = ignoreList
+        for h in extras.check(text) where !out.contains(where: { overlaps($0.range, h.range) }) {
+            out.append(h)
+        }
+        return out.sorted { $0.location < $1.location }
+    }
+
+    private func overlaps(_ a: NSRange, _ b: NSRange) -> Bool {
+        NSIntersectionRange(a, b).length > 0
+    }
+
+    private func onMain<T>(_ work: @escaping () -> T) -> T {
+        Thread.isMainThread ? work() : DispatchQueue.main.sync(execute: work)
+    }
+}

Sources/GrammaGem/System/LiveMonitor.swift

@@ -2,17 +2,31 @@ import Foundation
 import AppKit
 import ApplicationServices
 
+/// A text area discovered on screen that has at least one grammar/spelling issue.
+struct DetectedField: Identifiable {
+    let id: String
+    let label: String
+    let roleName: String
+    let text: String
+    let suggestions: [Suggestion]
+    let element: AXUIElement
+    let isFocused: Bool
+}
+
 /// The always-on, menu-bar–resident monitor. While enabled, it periodically
-/// reads the focused text field (Accessibility API), runs the offline grammar
-/// engine, and publishes live suggestions — so the menu bar reflects issues as
-/// you type. It stays out of excluded apps/domains and never sends text anywhere.
+/// scans **every** text area in the frontmost window (Accessibility API), runs
+/// the offline grammar engine on each, and publishes the ones with issues — so
+/// GrammaGem reflects problems across the whole screen, not just the focused
+/// field. It stays out of excluded apps/domains and never sends text anywhere.
 @MainActor
 final class LiveMonitor: ObservableObject {
-    @Published private(set) var suggestions: [Suggestion] = []
-    @Published private(set) var activeAppName: String = ""
+    @Published private(set) var fields: [DetectedField] = []
+    @Published private(set) var scannedCount = 0
+    @Published private(set) var activeAppName = ""
     @Published private(set) var running = false
 
-    var issueCount: Int { suggestions.count }
+    /// Total number of issues across all detected text areas.
+    var issueCount: Int { fields.reduce(0) { $0 + $1.suggestions.count } }
 
     private let grammar: GrammarEngine
     private let detector: AppDetector
@@ -23,7 +37,7 @@ final class LiveMonitor: ObservableObject {
     private var enabled = false
     private var paused = false
     private var lastHash = 0
-    private let interval: TimeInterval = 1.3
+    private let interval: TimeInterval = 1.4
 
     init(grammar: GrammarEngine, detector: AppDetector, exclusions: Exclusions, capture: TextCapture) {
         self.grammar = grammar
@@ -32,24 +46,49 @@ final class LiveMonitor: ObservableObject {
         self.capture = capture
     }
 
-    /// Turn live monitoring on/off (driven by the "live underlines" preference).
-    func setEnabled(_ on: Bool) {
-        enabled = on
-        reconcile()
+    func setEnabled(_ on: Bool) { enabled = on; reconcile() }
+    func setPaused(_ p: Bool) { paused = p; reconcile() }
+
+    /// Re-scan now (e.g. after applying a fix).
+    func refreshSoon() { lastHash = 0; tick() }
+
+    // MARK: - Applying fixes
+
+    @discardableResult
+    func fixAll() -> Int {
+        let total = fields.reduce(0) { $0 + applyCorrection(to: $1) }
+        refreshSoon()
+        return total
     }
 
-    /// Global pause (also stops the hotkeys, handled in AppState).
-    func setPaused(_ p: Bool) {
-        paused = p
-        reconcile()
+    @discardableResult
+    func fix(_ field: DetectedField) -> Int {
+        let n = applyCorrection(to: field)
+        refreshSoon()
+        return n
     }
 
-    /// Re-run immediately (e.g. after a "fix all").
-    func refreshSoon() {
-        lastHash = 0
-        tick()
+    func apply(_ suggestion: Suggestion, in field: DetectedField) {
+        let ns = NSMutableString(string: field.text)
+        guard suggestion.location + suggestion.length <= ns.length else { return }
+        ns.replaceCharacters(in: suggestion.range, with: suggestion.replacement)
+        setValue(ns as String, on: field.element)
+        refreshSoon()
     }
 
+    private func applyCorrection(to field: DetectedField) -> Int {
+        let corrected = grammar.correct(field.text)
+        guard corrected != field.text else { return 0 }
+        setValue(corrected, on: field.element)
+        return field.suggestions.count
+    }
+
+    private func setValue(_ text: String, on element: AXUIElement) {
+        AXUIElementSetAttributeValue(element, kAXValueAttribute as CFString, text as CFTypeRef)
+    }
+
+    // MARK: - Scanning
+
     private func reconcile() {
         let shouldRun = enabled && !paused
         if shouldRun && timer == nil {
@@ -58,7 +97,7 @@ final class LiveMonitor: ObservableObject {
             let t = Timer.scheduledTimer(withTimeInterval: interval, repeats: true) { [weak self] _ in
                 Task { @MainActor in self?.tick() }
             }
-            t.tolerance = 0.4
+            t.tolerance = 0.5
             timer = t
         } else if !shouldRun {
             running = false
@@ -70,29 +109,52 @@ final class LiveMonitor: ObservableObject {
 
     private func tick() {
         guard enabled, !paused, AXIsProcessTrusted() else { clear(); return }
+        guard let app = NSWorkspace.shared.frontmostApplication else { clear(); return }
+        activeAppName = app.localizedName ?? ""
 
-        let front = detector.frontmost()
-        activeAppName = front?.name ?? ""
-
-        // Respect the page blocker.
-        if exclusions.isBlocked(bundleID: front?.bundleID, domain: detector.frontmostDomain()) {
+        if exclusions.isBlocked(bundleID: app.bundleIdentifier, domain: detector.frontmostDomain()) {
             clear()
             return
         }
 
-        guard let field = capture.focusedFieldText() else { clear(); return }
-        let text = field.text
-        guard text.count >= 3 else { clear(); return }
+        let focused = systemFocusedElement()
+        let scanned = TextFieldScanner.scan(pid: app.processIdentifier, focused: focused)
+        guard !scanned.isEmpty else { clear(); return }
 
-        let h = text.hashValue
-        if h == lastHash { return } // unchanged since last check
+        // Skip re-checking if nothing on screen changed.
+        var hasher = Hasher()
+        hasher.combine(app.bundleIdentifier ?? "")
+        for f in scanned { hasher.combine(f.text) }
+        let h = hasher.finalize()
+        if h == lastHash { return }
         lastHash = h
 
-        suggestions = grammar.check(text)
+        scannedCount = scanned.count
+        var detected: [DetectedField] = []
+        for (i, f) in scanned.enumerated() {
+            let suggestions = grammar.check(f.text)
+            guard !suggestions.isEmpty else { continue }
+            detected.append(DetectedField(
+                id: "\(f.roleName)#\(i)", label: f.label, roleName: f.roleName,
+                text: f.text, suggestions: suggestions, element: f.element, isFocused: f.isFocused))
+        }
+        // Focused field first.
+        detected.sort { ($0.isFocused ? 0 : 1) < ($1.isFocused ? 0 : 1) }
+        fields = detected
+    }
+
+    private func systemFocusedElement() -> AXUIElement? {
+        let system = AXUIElementCreateSystemWide()
+        var ref: CFTypeRef?
+        guard AXUIElementCopyAttributeValue(
+            system, kAXFocusedUIElementAttribute as CFString, &ref) == .success, let ref
+        else { return nil }
+        return (ref as! AXUIElement)
     }
 
     private func clear() {
-        if !suggestions.isEmpty { suggestions = [] }
+        if !fields.isEmpty { fields = [] }
+        scannedCount = 0
         lastHash = 0
     }
 }

Sources/GrammaGem/System/TextFieldScanner.swift

@@ -0,0 +1,91 @@
+import Foundation
+import AppKit
+import ApplicationServices
+
+/// A text element discovered in the frontmost window via the Accessibility tree.
+struct ScannedField {
+    let element: AXUIElement
+    let roleName: String
+    let label: String
+    let text: String
+    let isFocused: Bool
+}
+
+/// Walks the Accessibility tree of the frontmost window and collects every
+/// editable text element (text fields, text areas, combo/search boxes) with
+/// content — so GrammaGem can check *all* the text on screen, not just the one
+/// the cursor is in. Bounded so huge web/Electron trees can't stall the app.
+enum TextFieldScanner {
+    static func scan(
+        pid: pid_t, focused: AXUIElement?,
+        maxFields: Int = 30, maxVisited: Int = 4000
+    ) -> [ScannedField] {
+        let axApp = AXUIElementCreateApplication(pid)
+        guard let root = window(of: axApp) ?? optional(axApp) else { return [] }
+        var out: [ScannedField] = []
+        var visited = 0
+        walk(root, focused: focused, depth: 0, out: &out, visited: &visited,
+             maxFields: maxFields, maxVisited: maxVisited)
+        return out
+    }
+
+    private static func optional(_ el: AXUIElement) -> AXUIElement? { el }
+
+    private static func window(of axApp: AXUIElement) -> AXUIElement? {
+        for attr in [kAXFocusedWindowAttribute, kAXMainWindowAttribute] {
+            var ref: CFTypeRef?
+            if AXUIElementCopyAttributeValue(axApp, attr as CFString, &ref) == .success,
+               let ref { return (ref as! AXUIElement) }
+        }
+        return nil
+    }
+
+    private static func walk(
+        _ el: AXUIElement, focused: AXUIElement?, depth: Int,
+        out: inout [ScannedField], visited: inout Int, maxFields: Int, maxVisited: Int
+    ) {
+        if out.count >= maxFields || visited >= maxVisited || depth > 70 { return }
+        visited += 1
+
+        let role = string(el, kAXRoleAttribute) ?? ""
+        if role == kAXTextFieldRole as String
+            || role == kAXTextAreaRole as String
+            || role == kAXComboBoxRole as String {
+            if let value = string(el, kAXValueAttribute),
+               value.trimmingCharacters(in: .whitespacesAndNewlines).count >= 3 {
+                let label = string(el, kAXTitleAttribute)
+                    ?? string(el, kAXDescriptionAttribute)
+                    ?? string(el, kAXPlaceholderValueAttribute)
+                    ?? roleLabel(role)
+                let isFocused = focused != nil && CFEqual(el, focused!)
+                out.append(ScannedField(
+                    element: el, roleName: roleLabel(role),
+                    label: label, text: value, isFocused: isFocused))
+            }
+        }
+
+        var childrenRef: CFTypeRef?
+        if AXUIElementCopyAttributeValue(el, kAXChildrenAttribute as CFString, &childrenRef) == .success,
+           let kids = childrenRef as? [AXUIElement] {
+            for k in kids {
+                if out.count >= maxFields || visited >= maxVisited { break }
+                walk(k, focused: focused, depth: depth + 1, out: &out,
+                     visited: &visited, maxFields: maxFields, maxVisited: maxVisited)
+            }
+        }
+    }
+
+    private static func string(_ el: AXUIElement, _ attr: String) -> String? {
+        var ref: CFTypeRef?
+        guard AXUIElementCopyAttributeValue(el, attr as CFString, &ref) == .success else { return nil }
+        return ref as? String
+    }
+
+    private static func roleLabel(_ role: String) -> String {
+        switch role {
+        case kAXTextAreaRole as String: return "Text area"
+        case kAXComboBoxRole as String: return "Combo box"
+        default: return "Text field"
+        }
+    }
+}