Editable TextKit 2 spike !7

merged merged by cmc on 2026-10-05 01:03 UTC · krz/orgstar:phase1-editing-spike into main

9 files changed, +2213 −4

Layout: unified · split

Package.swift +10 −2

         .library(name: "OrgCore", targets: ["OrgCore"]),
         .library(name: "OrgDocument", targets: ["OrgDocument"]),
         .library(name: "OrgIndex", targets: ["OrgIndex"]),
-        .library(name: "OrgWorkspace", targets: ["OrgWorkspace"])
+        .library(name: "OrgWorkspace", targets: ["OrgWorkspace"]),
+        .library(name: "OrgPresentation", targets: ["OrgPresentation"]),
+        .library(name: "OrgEditorAppKit", targets: ["OrgEditorAppKit"]),
+        .executable(name: "OrgstarSpike", targets: ["OrgstarSpike"])
     ],
     dependencies: [
         .package(url: "https://github.com/groue/GRDB.swift", from: "7.11.1")
         .target(name: "OrgDocument", dependencies: ["OrgCore"]),
         .target(name: "OrgIndex", dependencies: ["OrgCore", .product(name: "GRDB", package: "GRDB.swift")]),
         .target(name: "OrgWorkspace", dependencies: ["OrgIndex"]),
+        .target(name: "OrgPresentation", dependencies: ["OrgCore"]),
+        .target(name: "OrgEditorAppKit", dependencies: ["OrgDocument", "OrgPresentation"]),
+        .executableTarget(name: "OrgstarSpike", dependencies: ["OrgEditorAppKit"]),
         .testTarget(name: "OrgCoreTests", dependencies: ["OrgCore"]),
         .testTarget(name: "OrgDocumentTests", dependencies: ["OrgDocument"]),
         .testTarget(name: "OrgIndexTests", dependencies: ["OrgIndex"]),
-        .testTarget(name: "OrgWorkspaceTests", dependencies: ["OrgWorkspace"])
+        .testTarget(name: "OrgWorkspaceTests", dependencies: ["OrgWorkspace"]),
+        .testTarget(name: "OrgPresentationTests", dependencies: ["OrgPresentation"]),
+        .testTarget(name: "OrgEditorAppKitTests", dependencies: ["OrgEditorAppKit"])
     ]
 )

Sources/OrgDocument/ViewState.swift +13 −2

     /// Drops folds that no longer sit at the start of a heading.
     public func pruned(to tree: OrgTree) -> ViewState {
-        let headings = Set(tree.root.descendants().filter { $0.kind == .heading }.map(\.range.lowerBound))
+        guard !folds.isEmpty else { return self }
-        return ViewState(selection: selection, folds: folds.intersection(headings))
+        return ViewState(selection: selection, folds: folds.filter { isHeadingStart($0, tree.root) })
     }
 }
+/// Descends only through the sections containing `offset`.
+func isHeadingStart(_ offset: Int, _ root: SyntaxNode) -> Bool {
+    var node = root
+    while let child = node.children.first(where: { $0.range.contains(offset) }) {
+        if child.kind == .heading { return child.range.lowerBound == offset }
+        guard child.kind == .section || child.kind == .zerothSection else { return false }
+        node = child
+    }
+    return false
+}
 /// An offset before an edit stays put; one at the start of a replaced range stays at its start;
 /// one inside it, at its end, or at an insertion point moves past the replacement.
 func mapOffset(_ offset: Int, _ sortedEdits: [TextEdit]) -> Int {

Sources/OrgEditorAppKit/OrgEditor.swift added +347

@@ -0,0 +1,347 @@
	1	#if os(macOS)
	2	import AppKit
	3	import OrgCore
	4	import OrgDocument
	5	import OrgPresentation
	6
	7	/// Hidden ranges, read by TextKit's enumeration callbacks, which may run off the main thread.
	8	final class HiddenRanges: @unchecked Sendable {
	9	private let lock = NSLock()
	10	private var ranges: [Range<Int>] = []
	11
	12	func set(_ new: [Range<Int>]) {
	13	lock.withLock { ranges = new }
	14	}
	15
	16	var all: [Range<Int>] {
	17	lock.withLock { ranges }
	18	}
	19
	20	func covers(_ start: Int, _ end: Int) -> Bool {
	21	lock.withLock { ranges.contains { $0.lowerBound <= start && end <= $0.upperBound } }
	22	}
	23
	24	func containing(_ offset: Int) -> Range<Int>? {
	25	lock.withLock { ranges.first { $0.lowerBound <= offset && offset < $0.upperBound } }
	26	}
	27	}
	28
	29	/// Folded heading starts, read by the layout-fragment callback.
	30	final class FoldedHeadings: @unchecked Sendable {
	31	private let lock = NSLock()
	32	private var starts: Set<Int> = []
	33
	34	func set(_ new: Set<Int>) {
	35	lock.withLock { starts = new }
	36	}
	37
	38	func contains(_ offset: Int) -> Bool {
	39	lock.withLock { starts.contains(offset) }
	40	}
	41	}
	42
	43	/// A TextKit 2 text view over a `DocumentState`. The text storage mirrors the document; every
	44	/// character edit goes through `DocumentState.apply`, and only the affected region is restyled.
	45	@MainActor
	46	public final class OrgEditor: NSObject {
	47	public let textView: NSTextView
	48	public private(set) var document: DocumentState
	49	public private(set) var view = ViewState()
	50	/// Called with the time from a character edit to restyled text.
	51	public var onEditTiming: ((Duration) -> Void)?
	52
	53	let hidden = HiddenRanges()
	54	let folded = FoldedHeadings()
	55	let theme = Theme()
	56	private var isLoading = false
	57	private var previousSelection = 0
	58
	59	public init(document: DocumentState, frame: NSRect = NSRect(x: 0, y: 0, width: 600, height: 800)) {
	60	self.document = document
	61	textView = NSTextView(usingTextLayoutManager: true)
	62	super.init()
	63	textView.frame = frame
	64	textView.isRichText = false
	65	textView.allowsUndo = true
	66	textView.isAutomaticQuoteSubstitutionEnabled = false
	67	textView.isAutomaticDashSubstitutionEnabled = false
	68	textView.isAutomaticTextReplacementEnabled = false
	69	textView.isAutomaticSpellingCorrectionEnabled = false
	70	textView.font = theme.font
	71	textView.typingAttributes = theme.base
	72	textView.isVerticallyResizable = true
	73	textView.autoresizingMask = [.width]
	74	textView.textContainer?.widthTracksTextView = true
	75	textView.delegate = self
	76	textView.textStorage?.delegate = self
	77	textLayoutManager.delegate = self
	78	textContentStorage.delegate = self
	79
	80	isLoading = true
	81	textView.string = document.text
	82	isLoading = false
	83	restyleOutsideEditing(0..<utf16Length)
	84	}
	85
	86	public var textLayoutManager: NSTextLayoutManager { textView.textLayoutManager! }
	87	var textContentStorage: NSTextContentStorage { textLayoutManager.textContentManager as! NSTextContentStorage }
	88	var utf16Length: Int { (textView.string as NSString).length }
	89
	90	/// A scroll view holding the text view, ready for a window.
	91	public func makeScrollView() -> NSScrollView {
	92	let scroll = NSScrollView(frame: textView.frame)
	93	scroll.hasVerticalScroller = true
	94	scroll.documentView = textView
	95	textView.minSize = NSSize(width: 0, height: scroll.contentSize.height)
	96	textView.maxSize = NSSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude)
	97	return scroll
	98	}
	99
	100	// MARK: - Saving
	101
	102	/// Saves through `saver`. When a merge changes the buffer, the text view is reloaded and
	103	/// folds are mapped through the change.
	104	@discardableResult
	105	public func save(using saver: Saver, to url: URL) throws -> SaveOutcome {
	106	let before = document.text
	107	let outcome = try saver.save(&document, to: url)
	108	if document.text != before {
	109	let edits = lineEdits(from: before, to: document.text)
	110	isLoading = true
	111	textView.string = document.text
	112	isLoading = false
	113	restyleOutsideEditing(0..<utf16Length)
	114	setFolds(view.mapped(through: edits).folds)
	115	}
	116	return outcome
	117	}
	118
	119	// MARK: - Folding
	120
	121	public func setFolds(_ folds: Set<Int>) {
	122	view.folds = folds
	123	view = view.pruned(to: document.tree)
	124	folded.set(view.folds)
	125	hidden.set(Presentation.hiddenRanges(document.tree, folds: view.folds))
	126	textLayoutManager.invalidateLayout(for: textLayoutManager.documentRange)
	127	textView.needsDisplay = true
	128	let caret = textView.selectedRange().location
	129	if let range = hidden.containing(caret) { setCaret(range.lowerBound - 1) }
	130	}
	131
	132	/// Folds or unfolds the heading whose line holds the caret. Returns false off a heading.
	133	@discardableResult
	134	public func toggleFoldAtCaret() -> Bool {
	135	guard let heading = Presentation.heading(containing: textView.selectedRange().location, in: document.tree) else { return false }
	136	var folds = view.folds
	137	if folds.contains(heading) { folds.remove(heading) } else { folds.insert(heading) }
	138	setFolds(folds)
	139	return true
	140	}
	141
	142	/// Folds every heading, or unfolds everything if anything is folded.
	143	public func toggleAllFolds() {
	144	setFolds(view.folds.isEmpty ? Set(Presentation.headings(document.tree)) : [])
	145	}
	146
	147	private func setCaret(_ offset: Int) {
	148	let clamped = max(0, min(offset, utf16Length))
	149	previousSelection = clamped
	150	textView.setSelectedRange(NSRange(location: clamped, length: 0))
	151	}
	152
	153	// MARK: - Styling
	154
	155	private func restyleOutsideEditing(_ range: Range<Int>) {
	156	guard let storage = textView.textStorage else { return }
	157	storage.beginEditing()
	158	restyle(range, in: storage)
	159	storage.endEditing()
	160	}
	161
	162	/// Sets attributes for whole lines in `range`. Safe inside `didProcessEditing`, where
	163	/// attribute changes are allowed and characters must not change.
	164	private func restyle(_ range: Range<Int>, in storage: NSTextStorage) {
	165	guard !range.isEmpty else { return }
	166	let whole = NSRange(range)
	167	storage.setAttributes(theme.base, range: whole)
	168	for run in Presentation.indents(document.tree, in: range) {
	169	guard let clipped = clip(run.range, to: range) else { continue }
	170	storage.addAttribute(.paragraphStyle, value: theme.paragraphStyle(firstLine: run.firstLine, wrapped: run.wrapped), range: clipped)
	171	}
	172	for run in Presentation.styles(document.tree, in: range) {
	173	guard let clipped = clip(run.range, to: range) else { continue }
	174	theme.apply(run.role, to: storage, range: clipped)
	175	}
	176	}
	177
	178	private func clip(_ run: Range<Int>, to range: Range<Int>) -> NSRange? {
	179	let clipped = run.clamped(to: range)
	180	return clipped.isEmpty ? nil : NSRange(clipped)
	181	}
	182
	183	/// The region an edit affects in one version of the tree: inside the innermost section
	184	/// holding the edited lines (plus the line after), every element that overlaps them or the
	185	/// line on either side. A changed heading line, or an added or removed heading, widens it
	186	/// to that section's whole own body. Run on the old and the new tree, the union covers
	187	/// elements that grew and elements that shrank.
	188	static func affectedRange(_ tree: OrgTree, _ text: NSString, _ start: Int, _ end: Int, touchedHeadings: Bool) -> Range<Int> {
	189	let lines = text.lineRange(for: NSRange(location: start, length: min(end + 1, text.length) - start))
	190	let lineRange = lines.location..<(lines.location + lines.length)
	191	let around = max(0, lineRange.lowerBound - 1)..<min(text.length, lineRange.upperBound + 1)
	192	var container = tree.root
	193	while let child = container.children.first(where: {
	194	($0.kind == .section \|\| $0.kind == .zerothSection)
	195	&& $0.range.lowerBound <= lineRange.lowerBound && lineRange.upperBound <= $0.range.upperBound
	196	}) {
	197	container = child
	198	}
	199	var lower = lineRange.lowerBound
	200	var upper = lineRange.upperBound
	201	let children = container.children
	202	for child in children where child.range.overlaps(around) {
	203	lower = min(lower, child.range.lowerBound)
	204	upper = max(upper, child.range.upperBound)
	205	}
	206	let heading = children.first { $0.kind == .heading }
	207	if touchedHeadings \|\| heading.map({ $0.range.overlaps(lineRange) }) == true {
	208	lower = min(lower, container.range.lowerBound)
	209	upper = max(upper, children.first { $0.kind == .section }?.range.lowerBound ?? container.range.upperBound)
	210	}
	211	return lower..<min(upper, text.length)
	212	}
	213
	214	// MARK: - Editing
	215
	216	fileprivate func storageEdited(range: NSRange, delta: Int) {
	217	guard !isLoading, let storage = textView.textStorage else { return }
	218	let clock = ContinuousClock()
	219	let start = clock.now
	220	let replacement = (storage.string as NSString).substring(with: range)
	221	let edit = TextEdit(range: range.location..<(range.location + range.length - delta), replacement: replacement)
	222	let oldText = document.text as NSString
	223	let newText = storage.string as NSString
	224	let newEnd = edit.range.lowerBound + replacement.utf16.count
	225	let touchedHeadings = Self.headingLineNear(edit.range.lowerBound, edit.range.upperBound, in: oldText)
	226	\|\| Self.headingLineNear(edit.range.lowerBound, newEnd, in: newText)
	227	let oldAffected = Self.affectedRange(document.tree, oldText, edit.range.lowerBound, edit.range.upperBound, touchedHeadings: touchedHeadings)
	228	do {
	229	try document.apply([edit], baseRevision: document.revision)
	230	} catch {
	231	assertionFailure("text view and document disagree: \(error)")
	232	return
	233	}
	234	let oldHidden = hidden.all
	235	view = view.mapped(through: [edit]).pruned(to: document.tree)
	236	folded.set(view.folds)
	237	hidden.set(Presentation.hiddenRanges(document.tree, folds: view.folds))
	238	let newAffected = Self.affectedRange(document.tree, newText, edit.range.lowerBound, newEnd, touchedHeadings: touchedHeadings)
	239	let delta = edit.replacement.utf16.count - edit.range.count
	240	let oldMapped = oldAffected.lowerBound..<(oldAffected.upperBound >= edit.range.upperBound ? oldAffected.upperBound + delta : newEnd)
	241	restyle(min(oldMapped.lowerBound, newAffected.lowerBound)..<min(max(oldMapped.upperBound, newAffected.upperBound), newText.length), in: storage)
	242	if hidden.all != oldHidden.map({ mapRange($0, through: edit) }) {
	243	textLayoutManager.invalidateLayout(for: textLayoutManager.documentRange)
	244	}
	245	onEditTiming?(clock.now - start)
	246	}
	247
	248	/// Whether a heading line touches `start..<end` or starts right after it, where joining
	249	/// lines could take it away.
	250	static func headingLineNear(_ start: Int, _ end: Int, in text: NSString) -> Bool {
	251	let length = min(end + 1, text.length) - start
	252	guard length >= 0 else { return false }
	253	let lines = text.substring(with: text.lineRange(for: NSRange(location: start, length: length)))
	254	return lines.split(separator: "\n", omittingEmptySubsequences: false).contains { line in
	255	let stars = line.prefix { $0 == "*" }
	256	let after = line.dropFirst(stars.count)
	257	return !stars.isEmpty && (after.isEmpty \|\| after.first == " " \|\| after.first == "\t" \|\| after.first == "\r")
	258	}
	259	}
	260
	261	private func mapRange(_ range: Range<Int>, through edit: TextEdit) -> Range<Int> {
	262	let mapped = ViewState(selection: [range]).mapped(through: [edit]).selection[0]
	263	return mapped
	264	}
	265
	266	/// Keeps the caret out of folded text: moving forward into a fold jumps past it, moving
	267	/// back jumps to the end of the heading line.
	268	fileprivate func selectionChanged() {
	269	let selection = textView.selectedRange()
	270	defer { previousSelection = selection.location }
	271	guard selection.length == 0, let range = hidden.containing(selection.location) else { return }
	272	setCaret(selection.location >= previousSelection ? range.upperBound : range.lowerBound - 1)
	273	}
	274	}
	275
	276	extension OrgEditor: NSTextViewDelegate {
	277	public func textView(_ textView: NSTextView, doCommandBy selector: Selector) -> Bool {
	278	switch selector {
	279	case #selector(NSResponder.insertTab(_:)): return toggleFoldAtCaret()
	280	case #selector(NSResponder.insertBacktab(_:)):
	281	toggleAllFolds()
	282	return true
	283	default: return false
	284	}
	285	}
	286
	287	public func textViewDidChangeSelection(_ notification: Notification) {
	288	selectionChanged()
	289	}
	290	}
	291
	292	extension OrgEditor: NSTextStorageDelegate {
	293	public nonisolated func textStorage(
	294	_ textStorage: NSTextStorage, didProcessEditing editedMask: NSTextStorageEditActions, range editedRange: NSRange, changeInLength delta: Int
	295	) {
	296	guard editedMask.contains(.editedCharacters) else { return }
	297	MainActor.assumeIsolated { storageEdited(range: editedRange, delta: delta) }
	298	}
	299	}
	300
	301	extension OrgEditor: NSTextContentStorageDelegate {
	302	/// Folded text isn't enumerated, so it isn't laid out or drawn.
	303	public nonisolated func textContentManager(
	304	_ textContentManager: NSTextContentManager, shouldEnumerate textElement: NSTextElement, options: NSTextContentManager.EnumerationOptions = []
	305	) -> Bool {
	306	guard let range = textElement.elementRange else { return true }
	307	let documentStart = textContentManager.documentRange.location
	308	let start = textContentManager.offset(from: documentStart, to: range.location)
	309	let end = textContentManager.offset(from: documentStart, to: range.endLocation)
	310	return !hidden.covers(start, end)
	311	}
	312	}
	313
	314	extension OrgEditor: NSTextLayoutManagerDelegate {
	315	public nonisolated func textLayoutManager(
	316	_ textLayoutManager: NSTextLayoutManager, textLayoutFragmentFor location: NSTextLocation, in textElement: NSTextElement
	317	) -> NSTextLayoutFragment {
	318	let range = textElement.elementRange
	319	if let range, let manager = textLayoutManager.textContentManager {
	320	let offset = manager.offset(from: manager.documentRange.location, to: range.location)
	321	if folded.contains(offset) { return FoldedHeadingFragment(textElement: textElement, range: range) }
	322	}
	323	return NSTextLayoutFragment(textElement: textElement, range: range)
	324	}
	325	}
	326
	327	/// A heading line drawn with an ellipsis after it, like org's folded headings.
	328	final class FoldedHeadingFragment: NSTextLayoutFragment, @unchecked Sendable {
	329	override func draw(at point: CGPoint, in context: CGContext) {
	330	super.draw(at: point, in: context)
	331	guard let line = textLineFragments.first else { return }
	332	let bounds = line.typographicBounds
	333	let ellipsis = NSAttributedString(string: " …", attributes: [
	334	.font: NSFont.monospacedSystemFont(ofSize: NSFont.systemFontSize, weight: .regular),
	335	.foregroundColor: NSColor.secondaryLabelColor,
	336	])
	337	NSGraphicsContext.saveGraphicsState()
	338	NSGraphicsContext.current = NSGraphicsContext(cgContext: context, flipped: true)
	339	ellipsis.draw(at: CGPoint(x: point.x + bounds.maxX, y: point.y + bounds.minY))
	340	NSGraphicsContext.restoreGraphicsState()
	341	}
	342
	343	override var renderingSurfaceBounds: CGRect {
	344	super.renderingSurfaceBounds.insetBy(dx: -40, dy: 0).offsetBy(dx: 40, dy: 0)
	345	}
	346	}
	347	#endif

Sources/OrgEditorAppKit/Theme.swift added +74

@@ -0,0 +1,74 @@
	1	#if os(macOS)
	2	import AppKit
	3	import OrgPresentation
	4
	5	/// Attributes for each style role. A fixed theme for now; the app's theme settings replace it.
	6	@MainActor
	7	struct Theme {
	8	let font = NSFont.monospacedSystemFont(ofSize: 13, weight: .regular)
	9
	10	var base: [NSAttributedString.Key: Any] {
	11	[.font: font, .foregroundColor: NSColor.textColor]
	12	}
	13
	14	/// Width of one column of the monospaced font.
	15	var column: CGFloat {
	16	("0" as NSString).size(withAttributes: [.font: font]).width
	17	}
	18
	19	func paragraphStyle(firstLine: Int, wrapped: Int) -> NSParagraphStyle {
	20	let style = NSMutableParagraphStyle()
	21	style.firstLineHeadIndent = CGFloat(firstLine) * column
	22	style.headIndent = CGFloat(wrapped) * column
	23	return style
	24	}
	25
	26	func apply(_ role: StyleRole, to storage: NSTextStorage, range: NSRange) {
	27	switch role {
	28	case .heading(let level):
	29	let size = font.pointSize + CGFloat(max(0, 4 - level))
	30	storage.addAttribute(.font, value: NSFont.monospacedSystemFont(ofSize: size, weight: .semibold), range: range)
	31	case .leadingStars:
	32	storage.addAttribute(.foregroundColor, value: NSColor.clear, range: range)
	33	case .todo:
	34	storage.addAttributes([.foregroundColor: NSColor.systemRed, .font: bold(storage, range)], range: range)
	35	case .done:
	36	storage.addAttributes([.foregroundColor: NSColor.systemGreen, .font: bold(storage, range)], range: range)
	37	case .priority:
	38	storage.addAttribute(.foregroundColor, value: NSColor.systemOrange, range: range)
	39	case .tags, .comment, .keyword, .metadata:
	40	storage.addAttribute(.foregroundColor, value: NSColor.secondaryLabelColor, range: range)
	41	case .bold:
	42	storage.addAttribute(.font, value: bold(storage, range), range: range)
	43	case .italic:
	44	storage.addAttribute(.font, value: NSFontManager.shared.convert(currentFont(storage, range), toHaveTrait: .italicFontMask), range: range)
	45	case .underline:
	46	storage.addAttribute(.underlineStyle, value: NSUnderlineStyle.single.rawValue, range: range)
	47	case .strikeThrough:
	48	storage.addAttribute(.strikethroughStyle, value: NSUnderlineStyle.single.rawValue, range: range)
	49	case .verbatim, .code, .inlineSource:
	50	storage.addAttribute(.backgroundColor, value: NSColor.quaternarySystemFill, range: range)
	51	case .markup, .linkMarkup, .blockDelimiter:
	52	storage.addAttribute(.foregroundColor, value: NSColor.tertiaryLabelColor, range: range)
	53	case .link:
	54	storage.addAttributes([.foregroundColor: NSColor.linkColor, .underlineStyle: NSUnderlineStyle.single.rawValue], range: range)
	55	case .timestamp:
	56	storage.addAttribute(.foregroundColor, value: NSColor.systemPurple, range: range)
	57	case .footnote, .cookie, .target, .macro, .latex:
	58	storage.addAttribute(.foregroundColor, value: NSColor.systemTeal, range: range)
	59	case .block:
	60	storage.addAttribute(.backgroundColor, value: NSColor.quaternarySystemFill, range: range)
	61	case .table, .rule:
	62	break
	63	}
	64	}
	65
	66	private func currentFont(_ storage: NSTextStorage, _ range: NSRange) -> NSFont {
	67	storage.attribute(.font, at: range.location, effectiveRange: nil) as? NSFont ?? font
	68	}
	69
	70	private func bold(_ storage: NSTextStorage, _ range: NSRange) -> NSFont {
	71	NSFontManager.shared.convert(currentFont(storage, range), toHaveTrait: .boldFontMask)
	72	}
	73	}
	74	#endif

Sources/OrgPresentation/Presentation.swift added +171

@@ -0,0 +1,171 @@
	1	import OrgCore
	2
	3	/// What a range of text is, for styling. Platform adapters map roles to attributes.
	4	public enum StyleRole: Hashable, Sendable {
	5	/// A whole heading line.
	6	case heading(level: Int)
	7	/// All stars of a heading but the last, hidden as in `org-hide-leading-stars`.
	8	case leadingStars
	9	case todo, done, priority, tags
	10	case bold, italic, underline, strikeThrough, verbatim, code
	11	/// Emphasis markers.
	12	case markup
	13	case link
	14	/// Brackets and the target of a described link.
	15	case linkMarkup
	16	case timestamp, footnote, cookie, target, macro, latex, inlineSource
	17	case comment, keyword
	18	/// Planning lines, drawers, property drawers, clock lines.
	19	case metadata
	20	case block, blockDelimiter, table, rule
	21	}
	22
	23	public struct StyleRun: Sendable, Equatable {
	24	public let range: Range<Int>
	25	public let role: StyleRole
	26	}
	27
	28	/// org-indent: how many columns a run of whole lines starts in.
	29	public struct IndentRun: Sendable, Equatable {
	30	public let range: Range<Int>
	31	public let firstLine: Int
	32	/// Continuation lines of a wrapped paragraph.
	33	public let wrapped: Int
	34	}
	35
	36	public enum Presentation {
	37	/// Style runs for nodes and tokens overlapping `range`, outer before inner, so applying
	38	/// them in order lets inner roles win.
	39	public static func styles(_ tree: OrgTree, in range: Range<Int>) -> [StyleRun] {
	40	var runs: [StyleRun] = []
	41	visit(tree.root, range, tree.settings, &runs)
	42	return runs
	43	}
	44
	45	private static func visit(_ node: SyntaxNode, _ range: Range<Int>, _ settings: OrgSettings, _ runs: inout [StyleRun]) {
	46	if let role = role(of: node) { runs.append(StyleRun(range: node.range, role: role)) }
	47	switch node.kind {
	48	case .heading:
	49	for token in node.tokens {
	50	switch token.kind {
	51	case .stars where token.range.count > 1:
	52	runs.append(StyleRun(range: token.range.lowerBound..<(token.range.upperBound - 1), role: .leadingStars))
	53	case .todoKeyword:
	54	runs.append(StyleRun(range: token.range, role: settings.isDone(token.text) ? .done : .todo))
	55	case .priority:
	56	runs.append(StyleRun(range: token.range, role: .priority))
	57	case .tags:
	58	runs.append(StyleRun(range: token.range, role: .tags))
	59	default:
	60	break
	61	}
	62	}
	63	case .link:
	64	let described = node.children.contains { $0.kind == .linkDescription }
	65	for token in node.tokens where token.kind == .marker \|\| (described && token.kind == .linkPath) {
	66	runs.append(StyleRun(range: token.range, role: .linkMarkup))
	67	}
	68	case .bold, .italic, .underline, .strikeThrough, .verbatim, .code:
	69	for token in node.tokens where token.kind == .marker {
	70	runs.append(StyleRun(range: token.range, role: .markup))
	71	}
	72	case .block, .dynamicBlock:
	73	let lines = node.tokens.filter { $0.kind == .text }
	74	for token in [lines.first, lines.count > 1 ? lines.last : nil].compactMap({ $0 }) {
	75	runs.append(StyleRun(range: token.range, role: .blockDelimiter))
	76	}
	77	default:
	78	break
	79	}
	80	for child in node.children where child.range.overlaps(range) {
	81	visit(child, range, settings, &runs)
	82	}
	83	}
	84
	85	static func role(of node: SyntaxNode) -> StyleRole? {
	86	switch node.kind {
	87	case .heading: .heading(level: node.tokens.first { $0.kind == .stars }?.text.count ?? 1)
	88	case .bold: .bold
	89	case .italic: .italic
	90	case .underline: .underline
	91	case .strikeThrough: .strikeThrough
	92	case .verbatim: .verbatim
	93	case .code: .code
	94	case .link: .link
	95	case .timestamp: .timestamp
	96	case .footnoteReference, .footnoteDefinition: .footnote
	97	case .statisticsCookie: .cookie
	98	case .target: .target
	99	case .macro: .macro
	100	case .latexFragment: .latex
	101	case .inlineSourceBlock: .inlineSource
	102	case .comment: .comment
	103	case .keyword, .affiliatedKeyword: .keyword
	104	case .planning, .propertyDrawer, .drawer, .clock: .metadata
	105	case .block, .dynamicBlock, .fixedWidth: .block
	106	case .table: .table
	107	case .horizontalRule: .rule
	108	default: nil
	109	}
	110	}
	111
	112	/// Heading lines start at column 0, with wrapped title lines under the title; a section's
	113	/// own body starts one column past its stars.
	114	public static func indents(_ tree: OrgTree, in range: Range<Int>) -> [IndentRun] {
	115	var runs: [IndentRun] = []
	116	collectIndents(tree.root, range, &runs)
	117	return runs
	118	}
	119
	120	private static func collectIndents(_ node: SyntaxNode, _ range: Range<Int>, _ runs: inout [IndentRun]) {
	121	for section in node.children where section.kind == .section && section.range.overlaps(range) {
	122	let children = section.children
	123	guard let heading = children.first(where: { $0.kind == .heading }) else { continue }
	124	let level = heading.tokens.first { $0.kind == .stars }?.text.count ?? 1
	125	runs.append(IndentRun(range: heading.range, firstLine: 0, wrapped: level + 1))
	126	let bodyEnd = children.first { $0.kind == .section }?.range.lowerBound ?? section.range.upperBound
	127	if heading.range.upperBound < bodyEnd {
	128	runs.append(IndentRun(range: heading.range.upperBound..<bodyEnd, firstLine: level + 1, wrapped: level + 1))
	129	}
	130	collectIndents(section, range, &runs)
	131	}
	132	}
	133
	134	/// Ranges to hide for folded headings, given by their start offsets: from the end of the
	135	/// heading line to the end of its section. Sorted, without nested duplicates.
	136	public static func hiddenRanges(_ tree: OrgTree, folds: Set<Int>) -> [Range<Int>] {
	137	guard !folds.isEmpty else { return [] }
	138	var ranges: [Range<Int>] = []
	139	collectHidden(tree.root, folds, &ranges)
	140	return ranges
	141	}
	142
	143	private static func collectHidden(_ node: SyntaxNode, _ folds: Set<Int>, _ ranges: inout [Range<Int>]) {
	144	for section in node.children where section.kind == .section {
	145	guard let heading = section.children.first(where: { $0.kind == .heading }) else { continue }
	146	if folds.contains(heading.range.lowerBound) {
	147	if heading.range.upperBound < section.range.upperBound {
	148	ranges.append(heading.range.upperBound..<section.range.upperBound)
	149	}
	150	} else {
	151	collectHidden(section, folds, &ranges)
	152	}
	153	}
	154	}
	155
	156	/// Start offset of the heading whose line contains `offset`.
	157	public static func heading(containing offset: Int, in tree: OrgTree) -> Int? {
	158	var node = tree.root
	159	while let child = node.children.first(where: { $0.range.contains(offset) }) {
	160	if child.kind == .heading { return child.range.lowerBound }
	161	guard child.kind == .section \|\| child.kind == .zerothSection else { return nil }
	162	node = child
	163	}
	164	return nil
	165	}
	166
	167	/// Start offsets of every heading, for folding everything.
	168	public static func headings(_ tree: OrgTree) -> [Int] {
	169	tree.root.descendants().filter { $0.kind == .heading }.map(\.range.lowerBound)
	170	}
	171	}

Sources/OrgstarSpike/main.swift added +89

@@ -0,0 +1,89 @@
	1	#if os(macOS)
	2	import AppKit
	3	import OrgDocument
	4	import OrgEditorAppKit
	5
	6	/// A throwaway app for trying the editor by hand: `swift run OrgstarSpike path/to/file.org`.
	7	/// TAB on a heading folds it, Shift-TAB folds everything, ⌘S saves. Edit timings are printed
	8	/// every 50 edits.
	9	@MainActor
	10	final class SpikeDelegate: NSObject, NSApplicationDelegate {
	11	let url: URL
	12	var editor: OrgEditor?
	13	var window: NSWindow?
	14	var timings: [Duration] = []
	15
	16	init(url: URL) {
	17	self.url = url
	18	}
	19
	20	func applicationDidFinishLaunching(_ notification: Notification) {
	21	let bytes = (try? [UInt8](Data(contentsOf: url))) ?? []
	22	let editor = OrgEditor(document: DocumentState(bytes: bytes), frame: NSRect(x: 0, y: 0, width: 900, height: 1000))
	23	editor.onEditTiming = { [weak self] in self?.record($0) }
	24	let window = NSWindow(
	25	contentRect: NSRect(x: 100, y: 100, width: 900, height: 1000),
	26	styleMask: [.titled, .closable, .resizable, .miniaturizable], backing: .buffered, defer: false
	27	)
	28	window.title = url.lastPathComponent
	29	window.contentView = editor.makeScrollView()
	30	window.makeKeyAndOrderFront(nil)
	31	window.makeFirstResponder(editor.textView)
	32	self.editor = editor
	33	self.window = window
	34	buildMenu()
	35	NSApp.activate()
	36	}
	37
	38	func buildMenu() {
	39	let main = NSMenu()
	40	let appItem = NSMenuItem()
	41	appItem.submenu = NSMenu()
	42	appItem.submenu?.addItem(withTitle: "Quit", action: #selector(NSApplication.terminate(_:)), keyEquivalent: "q")
	43	let fileItem = NSMenuItem()
	44	fileItem.submenu = NSMenu(title: "File")
	45	fileItem.submenu?.addItem(withTitle: "Save", action: #selector(save), keyEquivalent: "s").target = self
	46	let editItem = NSMenuItem()
	47	editItem.submenu = NSMenu(title: "Edit")
	48	editItem.submenu?.addItem(withTitle: "Undo", action: Selector(("undo:")), keyEquivalent: "z")
	49	editItem.submenu?.addItem(withTitle: "Redo", action: Selector(("redo:")), keyEquivalent: "Z")
	50	editItem.submenu?.addItem(withTitle: "Cut", action: #selector(NSText.cut(_:)), keyEquivalent: "x")
	51	editItem.submenu?.addItem(withTitle: "Copy", action: #selector(NSText.copy(_:)), keyEquivalent: "c")
	52	editItem.submenu?.addItem(withTitle: "Paste", action: #selector(NSText.paste(_:)), keyEquivalent: "v")
	53	editItem.submenu?.addItem(withTitle: "Select All", action: #selector(NSText.selectAll(_:)), keyEquivalent: "a")
	54	[appItem, fileItem, editItem].forEach(main.addItem)
	55	NSApp.mainMenu = main
	56	}
	57
	58	@objc func save() {
	59	guard let editor else { return }
	60	let recovery = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)[0]
	61	.appendingPathComponent("Orgstar/Recovery")
	62	let saver = Saver(fileSystem: CoordinatedFileSystem(), recovery: FileRecoveryStore(directory: recovery))
	63	do {
	64	print("save:", try editor.save(using: saver, to: url))
	65	} catch {
	66	print("save failed:", error)
	67	}
	68	}
	69
	70	func record(_ duration: Duration) {
	71	timings.append(duration)
	72	guard timings.count % 50 == 0 else { return }
	73	let sorted = timings.sorted()
	74	print("edits: \(timings.count) p50 \(sorted[sorted.count / 2]) p95 \(sorted[sorted.count * 95 / 100])")
	75	}
	76
	77	func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool { true }
	78	}
	79
	80	guard CommandLine.arguments.count > 1 else {
	81	print("usage: OrgstarSpike path/to/file.org")
	82	exit(2)
	83	}
	84	let app = NSApplication.shared
	85	app.setActivationPolicy(.regular)
	86	let delegate = SpikeDelegate(url: URL(fileURLWithPath: CommandLine.arguments[1]))
	87	app.delegate = delegate
	88	app.run()
	89	#endif

Tests/OrgEditorAppKitTests/EditorTests.swift added +248

@@ -0,0 +1,248 @@
	1	import AppKit
	2	import OrgCore
	3	import OrgDocument
	4	import Testing
	5	@testable import OrgEditorAppKit
	6
	7	/// An editor in an offscreen window, laid out.
	8	@MainActor
	9	final class Harness {
	10	let editor: OrgEditor
	11	let window: NSWindow
	12
	13	init(_ text: String) {
	14	_ = NSApplication.shared
	15	editor = OrgEditor(document: DocumentState(bytes: Array(text.utf8)))
	16	window = NSWindow(contentRect: NSRect(x: 0, y: 0, width: 600, height: 800), styleMask: [.titled], backing: .buffered, defer: false)
	17	window.contentView = editor.makeScrollView()
	18	window.makeFirstResponder(editor.textView)
	19	layout()
	20	}
	21
	22	var textView: NSTextView { editor.textView }
	23	var string: String { textView.string }
	24
	25	func layout() {
	26	let manager = editor.textLayoutManager
	27	manager.ensureLayout(for: manager.documentRange)
	28	}
	29
	30	/// Text of each laid-out paragraph.
	31	var visibleLines: [String] {
	32	layout()
	33	let manager = editor.textLayoutManager
	34	var lines: [String] = []
	35	manager.enumerateTextLayoutFragments(from: manager.documentRange.location, options: [.ensuresLayout]) { fragment in
	36	let content = manager.textContentManager!
	37	let start = content.offset(from: content.documentRange.location, to: fragment.rangeInElement.location)
	38	let end = content.offset(from: content.documentRange.location, to: fragment.rangeInElement.endLocation)
	39	lines.append((self.string as NSString).substring(with: NSRange(location: start, length: end - start)))
	40	return true
	41	}
	42	return lines.filter { !$0.isEmpty }
	43	}
	44
	45	func caret(at offset: Int) {
	46	textView.setSelectedRange(NSRange(location: offset, length: 0))
	47	}
	48
	49	var caret: Int { textView.selectedRange().location }
	50
	51	func offset(of line: String) -> Int {
	52	(string as NSString).range(of: line).location
	53	}
	54
	55	func checkInSync() {
	56	#expect(editor.document.text == string)
	57	#expect(editor.document.tree.green == OrgParser.parse(string).green)
	58	}
	59	}
	60
	61	let outline = "* a\nbody\n** b\nmore\n* c\ntext\n"
	62
	63	@MainActor
	64	struct FoldingTests {
	65	@Test func foldingHidesTheSubtree() {
	66	let h = Harness(outline)
	67	#expect(h.visibleLines == ["* a\n", "body\n", "** b\n", "more\n", "* c\n", "text\n"])
	68	h.caret(at: 1)
	69	#expect(h.editor.toggleFoldAtCaret())
	70	#expect(h.visibleLines == ["* a\n", "* c\n", "text\n"])
	71	h.editor.toggleFoldAtCaret()
	72	#expect(h.visibleLines.count == 6)
	73	}
	74
	75	@Test func tabFoldsOnlyOnHeadings() {
	76	let h = Harness(outline)
	77	h.caret(at: 5)
	78	#expect(!h.editor.toggleFoldAtCaret())
	79	h.textView.doCommand(by: #selector(NSResponder.insertBacktab(_:)))
	80	#expect(h.visibleLines == ["* a\n", "* c\n"])
	81	}
	82
	83	@Test func caretMovesOverFoldedText() {
	84	let h = Harness(outline)
	85	h.caret(at: 1)
	86	h.editor.toggleFoldAtCaret()
	87	h.caret(at: 0)
	88	h.textView.moveDown(nil)
	89	#expect(h.caret >= h.offset(of: "* c") && h.caret < h.offset(of: "text"))
	90	h.caret(at: 3)
	91	h.textView.moveRight(nil)
	92	#expect(h.caret == h.offset(of: "* c"))
	93	h.textView.moveLeft(nil)
	94	#expect(h.caret == 3)
	95	}
	96
	97	@Test func copyingAcrossAFoldIncludesHiddenText() {
	98	let h = Harness(outline)
	99	h.caret(at: 1)
	100	h.editor.toggleFoldAtCaret()
	101	h.textView.setSelectedRange(NSRange(location: 0, length: h.offset(of: "text")))
	102	let pasteboard = NSPasteboard(name: NSPasteboard.Name("orgstar-test-\(UUID().uuidString)"))
	103	defer { pasteboard.releaseGlobally() }
	104	#expect(h.textView.writeSelection(to: pasteboard, types: h.textView.writablePasteboardTypes))
	105	#expect(pasteboard.string(forType: .string) == "* a\nbody\n** b\nmore\n* c\n")
	106	}
	107
	108	@Test func foldsFollowEdits() {
	109	let h = Harness(outline)
	110	h.caret(at: h.offset(of: "* c") + 1)
	111	h.editor.toggleFoldAtCaret()
	112	h.caret(at: 0)
	113	h.textView.insertText("new ", replacementRange: NSRange(location: 2, length: 0))
	114	#expect(h.visibleLines == ["* new a\n", "body\n", "** b\n", "more\n", "* c\n"])
	115	h.checkInSync()
	116	}
	117	}
	118
	119	@MainActor
	120	struct EditingTests {
	121	@Test func typingKeepsTheDocumentInSync() {
	122	let h = Harness(outline)
	123	h.caret(at: h.offset(of: "body") + 4)
	124	h.textView.insertText(" bold", replacementRange: h.textView.selectedRange())
	125	h.textView.insertNewline(nil)
	126	h.textView.insertText("* new heading", replacementRange: h.textView.selectedRange())
	127	h.textView.deleteBackward(nil)
	128	h.checkInSync()
	129	#expect(h.editor.document.isDirty)
	130	}
	131
	132	@Test func inputMethodComposition() {
	133	let h = Harness("* a\n")
	134	h.caret(at: 3)
	135	h.textView.setMarkedText("か", selectedRange: NSRange(location: 1, length: 0), replacementRange: NSRange(location: NSNotFound, length: 0))
	136	#expect(h.textView.hasMarkedText())
	137	h.textView.setMarkedText("かん", selectedRange: NSRange(location: 2, length: 0), replacementRange: NSRange(location: NSNotFound, length: 0))
	138	h.textView.insertText("漢", replacementRange: NSRange(location: NSNotFound, length: 0))
	139	#expect(!h.textView.hasMarkedText())
	140	#expect(h.string == "* a漢\n")
	141	h.checkInSync()
	142	}
	143
	144	@Test func undoKeepsTheDocumentInSync() {
	145	let h = Harness(outline)
	146	h.caret(at: 3)
	147	h.textView.insertText("xyz", replacementRange: h.textView.selectedRange())
	148	h.textView.breakUndoCoalescing()
	149	h.textView.undoManager?.undo()
	150	#expect(h.string == outline)
	151	h.checkInSync()
	152	}
	153
	154	@Test func styling() throws {
	155	let h = Harness("** b\nbody\n")
	156	let storage = try #require(h.textView.textStorage)
	157	#expect(storage.attribute(.foregroundColor, at: 0, effectiveRange: nil) as? NSColor == .clear)
	158	let style = try #require(storage.attribute(.paragraphStyle, at: 6, effectiveRange: nil) as? NSParagraphStyle)
	159	#expect(style.firstLineHeadIndent == 3 * h.editor.theme.column)
	160	h.caret(at: 0)
	161	h.textView.insertText("*", replacementRange: NSRange(location: 0, length: 0))
	162	let deeper = try #require(storage.attribute(.paragraphStyle, at: 7, effectiveRange: nil) as? NSParagraphStyle)
	163	#expect(deeper.firstLineHeadIndent == 4 * h.editor.theme.column)
	164	}
	165
	166	@Test func accessibilityReadsTheWholeText() {
	167	let h = Harness(outline)
	168	h.caret(at: 1)
	169	h.editor.toggleFoldAtCaret()
	170	#expect(h.textView.accessibilityValue() as? String == outline)
	171	h.textView.setSelectedRange(NSRange(location: 0, length: 3))
	172	#expect(h.textView.accessibilitySelectedText() == "* a")
	173	#expect(h.textView.accessibilityLine(for: h.offset(of: "* c")) >= 1)
	174	}
	175
	176	@Test func saveWritesAndClearsDirty() throws {
	177	let folder = FileManager.default.temporaryDirectory.appendingPathComponent("orgstar-\(UUID().uuidString)")
	178	try FileManager.default.createDirectory(at: folder, withIntermediateDirectories: true)
	179	defer { try? FileManager.default.removeItem(at: folder) }
	180	let file = folder.appendingPathComponent("a.org")
	181	try Data(outline.utf8).write(to: file)
	182	let h = Harness(outline)
	183	h.textView.insertText("x", replacementRange: NSRange(location: 0, length: 0))
	184	let saver = Saver(fileSystem: CoordinatedFileSystem(), recovery: FileRecoveryStore(directory: folder.appendingPathComponent("r")))
	185	#expect(try h.editor.save(using: saver, to: file) == .saved)
	186	#expect(!h.editor.document.isDirty)
	187	#expect(try String(contentsOf: file, encoding: .utf8) == "x" + outline)
	188	}
	189	}
	190
	191	@MainActor
	192	struct RestyleTests {
	193	func indent(_ h: Harness, at line: String) -> CGFloat? {
	194	let style = h.textView.textStorage?.attribute(.paragraphStyle, at: h.offset(of: line), effectiveRange: nil) as? NSParagraphStyle
	195	return style.map { $0.firstLineHeadIndent / h.editor.theme.column }
	196	}
	197
	198	@Test func newHeadingReindentsTheLinesItTakesOver() {
	199	let h = Harness("* a\none\ntwo\nthree\n")
	200	h.textView.insertText("** b\n", replacementRange: NSRange(location: h.offset(of: "two"), length: 0))
	201	#expect(indent(h, at: "one") == 2)
	202	#expect(indent(h, at: "three") == 3)
	203	h.checkInSync()
	204	}
	205
	206	@Test func joiningAwayAHeadingReindentsItsBody() {
	207	let h = Harness("* a\none\n** b\ntwo\nthree\n")
	208	h.textView.insertText("", replacementRange: NSRange(location: h.offset(of: "** b") - 1, length: 1))
	209	#expect(indent(h, at: "three") == 2)
	210	h.checkInSync()
	211	}
	212
	213	@Test func typingASpaceAfterAStarMakesAHeading() {
	214	let h = Harness("* a\n*x\nbody\nmore\n")
	215	h.textView.insertText(" ", replacementRange: NSRange(location: h.offset(of: "*x") + 1, length: 0))
	216	#expect(indent(h, at: "more") == 2)
	217	h.checkInSync()
	218	}
	219	}
	220
	221	@MainActor
	222	struct RestyleFuzzTests {
	223	/// After each random edit, the restyled text must equal a fresh editor's full styling. Set
	224	/// `ORGSTAR_RESTYLE_EDITS` and `ORGSTAR_FUZZ_SEED` for longer runs.
	225	@Test func incrementalRestyleEqualsFullRestyle() throws {
	226	let environment = ProcessInfo.processInfo.environment
	227	var state = UInt64(environment["ORGSTAR_FUZZ_SEED"] ?? "") ?? 20261006
	228	let count = Int(environment["ORGSTAR_RESTYLE_EDITS"] ?? "") ?? 300
	229	func next(_ bound: Int) -> Int {
	230	state = state &* 6364136223846793005 &+ 1442695040888963407
	231	return Int((state >> 33) % UInt64(bound))
	232	}
	233	let pieces = ["* ", "** ", "", " ", "\n", "x", "b*", "TODO ", "- ", "\| a \|", "#+begin_src\n", "#+end_src\n", ":PROPERTIES:\n", ":END:\n", "[[l][d]]", "<2026-10-04 Sun>"]
	234	let h = Harness("* a\nbody b\n** b\n- item\nmore\n* c\ntext\n")
	235	for n in 0..<count {
	236	let length = (h.string as NSString).length
	237	let start = next(length + 1)
	238	let end = min(length, start + next(4))
	239	let replacement = next(3) == 0 ? "" : pieces[next(pieces.count)]
	240	h.textView.insertText(replacement, replacementRange: NSRange(location: start, length: end - start))
	241	let fresh = Harness(h.string)
	242	let same = h.textView.textStorage!.isEqual(to: fresh.textView.textStorage!)
	243	#expect(same, "edit \(n): \(start)..<\(end) \(replacement.debugDescription) -> \(h.string.debugDescription)")
	244	if !same { break }
	245	}
	246	h.checkInSync()
	247	}
	248	}

Tests/OrgPresentationTests/PresentationTests.swift added +78

@@ -0,0 +1,78 @@
	1	import OrgCore
	2	import Testing
	3	@testable import OrgPresentation
	4
	5	func roles(_ text: String) -> [String] {
	6	let tree = OrgParser.parse(text)
	7	let utf16 = Array(text.utf16)
	8	return Presentation.styles(tree, in: 0..<utf16.count).map { run in
	9	"\(run.role):\(String(decoding: utf16[run.range], as: UTF16.self))"
	10	}
	11	}
	12
	13	struct StyleTests {
	14	@Test func headingParts() {
	15	#expect(roles("** DONE [#A] Ship it :work:\n") == [
	16	"heading(level: 2):** DONE [#A] Ship it :work:\n",
	17	"leadingStars:*", "done:DONE", "priority:[#A]", "tags::work:",
	18	"bold:it", "markup:", "markup:",
	19	])
	20	}
	21
	22	@Test func describedLinksDimTheirTarget() {
	23	#expect(roles("[[https://a.b][site]]\n") == [
	24	"link:[[https://a.b][site]]", "linkMarkup:[[", "linkMarkup:https://a.b", "linkMarkup:][", "linkMarkup:]]",
	25	])
	26	#expect(roles("[[https://a.b]]\n") == ["link:[[https://a.b]]", "linkMarkup:[[", "linkMarkup:]]"])
	27	}
	28
	29	@Test func blocksAndMetadata() {
	30	#expect(roles("#+begin_src sh\necho\n#+end_src\n") == [
	31	"block:#+begin_src sh\necho\n#+end_src\n", "blockDelimiter:#+begin_src sh", "blockDelimiter:#+end_src",
	32	])
	33	#expect(roles("* a\nSCHEDULED: <2026-10-04 Sun>\n").contains("metadata:SCHEDULED: <2026-10-04 Sun>\n"))
	34	}
	35
	36	@Test func onlyRunsOverlappingTheRange() {
	37	let text = "* a\nfirst b\n* c\nsecond d\n"
	38	let tree = OrgParser.parse(text)
	39	let runs = Presentation.styles(tree, in: 17..<28)
	40	#expect(!runs.contains { $0.range == 10..<13 })
	41	#expect(runs.contains { $0.range == 25..<28 && $0.role == .bold })
	42	}
	43	}
	44
	45	struct IndentTests {
	46	@Test func bodiesIndentPastTheirStars() {
	47	let text = "pre\n* a\nbody\n** b\nmore\n"
	48	let runs = Presentation.indents(OrgParser.parse(text), in: 0..<text.utf16.count)
	49	#expect(runs == [
	50	IndentRun(range: 4..<8, firstLine: 0, wrapped: 2),
	51	IndentRun(range: 8..<13, firstLine: 2, wrapped: 2),
	52	IndentRun(range: 13..<18, firstLine: 0, wrapped: 3),
	53	IndentRun(range: 18..<23, firstLine: 3, wrapped: 3),
	54	])
	55	}
	56	}
	57
	58	struct FoldTests {
	59	let text = "* a\nbody\n** b\nmore\n* c\ntext\n"
	60
	61	@Test func hiddenRanges() {
	62	let tree = OrgParser.parse(text)
	63	#expect(Presentation.hiddenRanges(tree, folds: [0]) == [4..<19])
	64	#expect(Presentation.hiddenRanges(tree, folds: [9]) == [14..<19])
	65	#expect(Presentation.hiddenRanges(tree, folds: [0, 9]) == [4..<19])
	66	#expect(Presentation.hiddenRanges(tree, folds: [19]) == [23..<28])
	67	#expect(Presentation.hiddenRanges(OrgParser.parse("* a"), folds: [0]).isEmpty)
	68	}
	69
	70	@Test func headingContaining() {
	71	let tree = OrgParser.parse(text)
	72	#expect(Presentation.heading(containing: 2, in: tree) == 0)
	73	#expect(Presentation.heading(containing: 3, in: tree) == 0)
	74	#expect(Presentation.heading(containing: 5, in: tree) == nil)
	75	#expect(Presentation.heading(containing: 10, in: tree) == 9)
	76	#expect(Presentation.headings(tree) == [0, 9, 19])
	77	}
	78	}

docs/plans/2026-10-04-editing-spike.md added +1183

@@ -0,0 +1,1183 @@
	1	# Editable TextKit 2 Spike Implementation Plan
	2
	3	> For agentic workers: REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
	4
	5	Goal: Prove that a TextKit 2 text view can fold org subtrees and show org-indent while caret movement, selection, input methods, VoiceOver and copy/paste stay correct, with typing restyled inside a 16 ms frame. Find what doesn't work before phase 2 builds on it.
	6
	7	Architecture: `OrgPresentation` is the platform-free layout policy: style runs, org-indent columns and hidden ranges, all computed from the tree. `OrgEditorAppKit` maps that policy onto an `NSTextView` with TextKit 2: folded paragraphs are skipped by `NSTextContentManagerDelegate.shouldEnumerate`, folded headings draw an ellipsis from a custom `NSTextLayoutFragment`, and every character edit flows from the text storage into `DocumentState.apply`. Only the affected region is restyled: the elements around the edit in the innermost section, computed on both the old and the new tree. `OrgstarSpike` is a throwaway app for trying it by hand.
	8
	9	Tech Stack: Swift 6.2 tools, Swift Testing, AppKit, TextKit 2.
	10
	11	Spec: `docs/design.md`, "iOS considerations" (editor view row) and the phase 1 editing spike gate.
	12
	13	## Global Constraints
	14
	15	- `OrgPresentation` imports only `OrgCore`; it builds for iOS.
	16	- The text storage and `DocumentState` hold the same text after every edit, and the tree equals a full parse.
	17	- Incrementally restyled text equals a fresh editor's full styling after every edit.
	18	- Folded text stays in the storage: copy, accessibility and saving see all of it.
	19
	20	## Findings
	21
	22	Measured in release builds on an M-series Mac (not yet the M1 Air reference machine).
	23
	24	\| Check \| Result \|
	25	\| --- \| --- \|
	26	\| Folding by skipping enumeration \| Works; layout drops folded paragraphs; ellipsis drawn after folded headings \|
	27	\| Caret \| `moveDown` skips folds; `moveRight`/`moveLeft` would enter hidden text, so the editor moves the caret across the fold \|
	28	\| Copy across a fold \| Includes the hidden text \|
	29	\| Input methods \| Marked text and commit keep the document in sync \|
	30	\| Undo (`NSTextView`'s undo manager) \| Keeps the document in sync \|
	31	\| Accessibility \| `accessibilityValue` is the whole file, folds included; selection and line queries work. A manual VoiceOver pass is still needed (below) \|
	32	\| Typing, p95 \| 5.8 ms on a 1.5 MB file, 3.4 ms on 0.86 MB (gate 16 ms) \|
	33	\| Blank line in a 1.2 MB top-level section \| 256 ms; the reparse covers the whole top-level section (gate 16 ms) \|
	34	\| Open: parse + load and style \| 313 + 124 ms for 1.5 MB; 126 + 101 ms for 0.86 MB (gate 100 ms for 1 MB) \|
	35	\| Restyle correctness \| 10,500 random edits over seven seeds match a fresh full styling \|
	36
	37	Two bugs the differential test found and the plan fixes: a line split off by an inserted newline kept the old line's style, and a block or drawer whose delimiters changed left stale styling below the edit (fixed by restyling the union of the old and new trees' affected ranges).
	38
	39	Work for the performance plan: reparse structural edits within the innermost section instead of the top-level section; a faster parser (about 3x for the open gate); style the visible region first on open and the rest after.
	40
	41	Manual VoiceOver checklist (run `swift run OrgstarSpike <file>`, turn on VoiceOver):
	42	- [ ] Line by line through a folded heading skips to the next visible heading.
	43	- [ ] Reading a heading with tags and a TODO keyword is understandable.
	44	- [ ] Selection announcements are correct across a fold.
	45
	46	## File structure
	47
	48	\| File \| Responsibility \|
	49	\| --- \| --- \|
	50	\| `Sources/OrgPresentation/Presentation.swift` \| Style roles and runs, indent runs, hidden ranges, heading lookup \|
	51	\| `Sources/OrgEditorAppKit/OrgEditor.swift` \| TextKit 2 editor: sync, folding, caret, restyle region, save \|
	52	\| `Sources/OrgEditorAppKit/Theme.swift` \| Attributes per style role \|
	53	\| `Sources/OrgstarSpike/main.swift` \| Runnable spike app \|
	54	\| `Sources/OrgDocument/ViewState.swift` \| `pruned(to:)` descends only through containing sections \|
	55
	56	---
	57
	58	### Task 1: Presentation policy
	59
	60	Files:
	61	- Modify: `Package.swift` (add `OrgPresentation`)
	62	- Create: `Sources/OrgPresentation/Presentation.swift`
	63	- Test: `Tests/OrgPresentationTests/PresentationTests.swift`
	64
	65	Interfaces:
	66	- Produces: `StyleRole`, `StyleRun`, `IndentRun`, `Presentation.styles(_:in:)`, `Presentation.indents(_:in:)`, `Presentation.hiddenRanges(_:folds:)`, `Presentation.heading(containing:in:)`, `Presentation.headings(_:)`.
	67
	68	- [ ] Step 1: Write the failing tests
	69
	70	```swift
	71	import OrgCore
	72	import Testing
	73	@testable import OrgPresentation
	74
	75	func roles(_ text: String) -> [String] {
	76	let tree = OrgParser.parse(text)
	77	let utf16 = Array(text.utf16)
	78	return Presentation.styles(tree, in: 0..<utf16.count).map { run in
	79	"\(run.role):\(String(decoding: utf16[run.range], as: UTF16.self))"
	80	}
	81	}
	82
	83	struct StyleTests {
	84	@Test func headingParts() {
	85	#expect(roles("** DONE [#A] Ship it :work:\n") == [
	86	"heading(level: 2):** DONE [#A] Ship it :work:\n",
	87	"leadingStars:*", "done:DONE", "priority:[#A]", "tags::work:",
	88	"bold:it", "markup:", "markup:",
	89	])
	90	}
	91
	92	@Test func describedLinksDimTheirTarget() {
	93	#expect(roles("[[https://a.b][site]]\n") == [
	94	"link:[[https://a.b][site]]", "linkMarkup:[[", "linkMarkup:https://a.b", "linkMarkup:][", "linkMarkup:]]",
	95	])
	96	#expect(roles("[[https://a.b]]\n") == ["link:[[https://a.b]]", "linkMarkup:[[", "linkMarkup:]]"])
	97	}
	98
	99	@Test func blocksAndMetadata() {
	100	#expect(roles("#+begin_src sh\necho\n#+end_src\n") == [
	101	"block:#+begin_src sh\necho\n#+end_src\n", "blockDelimiter:#+begin_src sh", "blockDelimiter:#+end_src",
	102	])
	103	#expect(roles("* a\nSCHEDULED: <2026-10-04 Sun>\n").contains("metadata:SCHEDULED: <2026-10-04 Sun>\n"))
	104	}
	105
	106	@Test func onlyRunsOverlappingTheRange() {
	107	let text = "* a\nfirst b\n* c\nsecond d\n"
	108	let tree = OrgParser.parse(text)
	109	let runs = Presentation.styles(tree, in: 17..<28)
	110	#expect(!runs.contains { $0.range == 10..<13 })
	111	#expect(runs.contains { $0.range == 25..<28 && $0.role == .bold })
	112	}
	113	}
	114
	115	struct IndentTests {
	116	@Test func bodiesIndentPastTheirStars() {
	117	let text = "pre\n* a\nbody\n** b\nmore\n"
	118	let runs = Presentation.indents(OrgParser.parse(text), in: 0..<text.utf16.count)
	119	#expect(runs == [
	120	IndentRun(range: 4..<8, firstLine: 0, wrapped: 2),
	121	IndentRun(range: 8..<13, firstLine: 2, wrapped: 2),
	122	IndentRun(range: 13..<18, firstLine: 0, wrapped: 3),
	123	IndentRun(range: 18..<23, firstLine: 3, wrapped: 3),
	124	])
	125	}
	126	}
	127
	128	struct FoldTests {
	129	let text = "* a\nbody\n** b\nmore\n* c\ntext\n"
	130
	131	@Test func hiddenRanges() {
	132	let tree = OrgParser.parse(text)
	133	#expect(Presentation.hiddenRanges(tree, folds: [0]) == [4..<19])
	134	#expect(Presentation.hiddenRanges(tree, folds: [9]) == [14..<19])
	135	#expect(Presentation.hiddenRanges(tree, folds: [0, 9]) == [4..<19])
	136	#expect(Presentation.hiddenRanges(tree, folds: [19]) == [23..<28])
	137	#expect(Presentation.hiddenRanges(OrgParser.parse("* a"), folds: [0]).isEmpty)
	138	}
	139
	140	@Test func headingContaining() {
	141	let tree = OrgParser.parse(text)
	142	#expect(Presentation.heading(containing: 2, in: tree) == 0)
	143	#expect(Presentation.heading(containing: 3, in: tree) == 0)
	144	#expect(Presentation.heading(containing: 5, in: tree) == nil)
	145	#expect(Presentation.heading(containing: 10, in: tree) == 9)
	146	#expect(Presentation.headings(tree) == [0, 9, 19])
	147	}
	148	}
	149	```
	150
	151	- [ ] Step 2: Implement
	152
	153	```swift
	154	import OrgCore
	155
	156	/// What a range of text is, for styling. Platform adapters map roles to attributes.
	157	public enum StyleRole: Hashable, Sendable {
	158	/// A whole heading line.
	159	case heading(level: Int)
	160	/// All stars of a heading but the last, hidden as in `org-hide-leading-stars`.
	161	case leadingStars
	162	case todo, done, priority, tags
	163	case bold, italic, underline, strikeThrough, verbatim, code
	164	/// Emphasis markers.
	165	case markup
	166	case link
	167	/// Brackets and the target of a described link.
	168	case linkMarkup
	169	case timestamp, footnote, cookie, target, macro, latex, inlineSource
	170	case comment, keyword
	171	/// Planning lines, drawers, property drawers, clock lines.
	172	case metadata
	173	case block, blockDelimiter, table, rule
	174	}
	175
	176	public struct StyleRun: Sendable, Equatable {
	177	public let range: Range<Int>
	178	public let role: StyleRole
	179	}
	180
	181	/// org-indent: how many columns a run of whole lines starts in.
	182	public struct IndentRun: Sendable, Equatable {
	183	public let range: Range<Int>
	184	public let firstLine: Int
	185	/// Continuation lines of a wrapped paragraph.
	186	public let wrapped: Int
	187	}
	188
	189	public enum Presentation {
	190	/// Style runs for nodes and tokens overlapping `range`, outer before inner, so applying
	191	/// them in order lets inner roles win.
	192	public static func styles(_ tree: OrgTree, in range: Range<Int>) -> [StyleRun] {
	193	var runs: [StyleRun] = []
	194	visit(tree.root, range, tree.settings, &runs)
	195	return runs
	196	}
	197
	198	private static func visit(_ node: SyntaxNode, _ range: Range<Int>, _ settings: OrgSettings, _ runs: inout [StyleRun]) {
	199	if let role = role(of: node) { runs.append(StyleRun(range: node.range, role: role)) }
	200	switch node.kind {
	201	case .heading:
	202	for token in node.tokens {
	203	switch token.kind {
	204	case .stars where token.range.count > 1:
	205	runs.append(StyleRun(range: token.range.lowerBound..<(token.range.upperBound - 1), role: .leadingStars))
	206	case .todoKeyword:
	207	runs.append(StyleRun(range: token.range, role: settings.isDone(token.text) ? .done : .todo))
	208	case .priority:
	209	runs.append(StyleRun(range: token.range, role: .priority))
	210	case .tags:
	211	runs.append(StyleRun(range: token.range, role: .tags))
	212	default:
	213	break
	214	}
	215	}
	216	case .link:
	217	let described = node.children.contains { $0.kind == .linkDescription }
	218	for token in node.tokens where token.kind == .marker \|\| (described && token.kind == .linkPath) {
	219	runs.append(StyleRun(range: token.range, role: .linkMarkup))
	220	}
	221	case .bold, .italic, .underline, .strikeThrough, .verbatim, .code:
	222	for token in node.tokens where token.kind == .marker {
	223	runs.append(StyleRun(range: token.range, role: .markup))
	224	}
	225	case .block, .dynamicBlock:
	226	let lines = node.tokens.filter { $0.kind == .text }
	227	for token in [lines.first, lines.count > 1 ? lines.last : nil].compactMap({ $0 }) {
	228	runs.append(StyleRun(range: token.range, role: .blockDelimiter))
	229	}
	230	default:
	231	break
	232	}
	233	for child in node.children where child.range.overlaps(range) {
	234	visit(child, range, settings, &runs)
	235	}
	236	}
	237
	238	static func role(of node: SyntaxNode) -> StyleRole? {
	239	switch node.kind {
	240	case .heading: .heading(level: node.tokens.first { $0.kind == .stars }?.text.count ?? 1)
	241	case .bold: .bold
	242	case .italic: .italic
	243	case .underline: .underline
	244	case .strikeThrough: .strikeThrough
	245	case .verbatim: .verbatim
	246	case .code: .code
	247	case .link: .link
	248	case .timestamp: .timestamp
	249	case .footnoteReference, .footnoteDefinition: .footnote
	250	case .statisticsCookie: .cookie
	251	case .target: .target
	252	case .macro: .macro
	253	case .latexFragment: .latex
	254	case .inlineSourceBlock: .inlineSource
	255	case .comment: .comment
	256	case .keyword, .affiliatedKeyword: .keyword
	257	case .planning, .propertyDrawer, .drawer, .clock: .metadata
	258	case .block, .dynamicBlock, .fixedWidth: .block
	259	case .table: .table
	260	case .horizontalRule: .rule
	261	default: nil
	262	}
	263	}
	264
	265	/// Heading lines start at column 0, with wrapped title lines under the title; a section's
	266	/// own body starts one column past its stars.
	267	public static func indents(_ tree: OrgTree, in range: Range<Int>) -> [IndentRun] {
	268	var runs: [IndentRun] = []
	269	collectIndents(tree.root, range, &runs)
	270	return runs
	271	}
	272
	273	private static func collectIndents(_ node: SyntaxNode, _ range: Range<Int>, _ runs: inout [IndentRun]) {
	274	for section in node.children where section.kind == .section && section.range.overlaps(range) {
	275	let children = section.children
	276	guard let heading = children.first(where: { $0.kind == .heading }) else { continue }
	277	let level = heading.tokens.first { $0.kind == .stars }?.text.count ?? 1
	278	runs.append(IndentRun(range: heading.range, firstLine: 0, wrapped: level + 1))
	279	let bodyEnd = children.first { $0.kind == .section }?.range.lowerBound ?? section.range.upperBound
	280	if heading.range.upperBound < bodyEnd {
	281	runs.append(IndentRun(range: heading.range.upperBound..<bodyEnd, firstLine: level + 1, wrapped: level + 1))
	282	}
	283	collectIndents(section, range, &runs)
	284	}
	285	}
	286
	287	/// Ranges to hide for folded headings, given by their start offsets: from the end of the
	288	/// heading line to the end of its section. Sorted, without nested duplicates.
	289	public static func hiddenRanges(_ tree: OrgTree, folds: Set<Int>) -> [Range<Int>] {
	290	guard !folds.isEmpty else { return [] }
	291	var ranges: [Range<Int>] = []
	292	collectHidden(tree.root, folds, &ranges)
	293	return ranges
	294	}
	295
	296	private static func collectHidden(_ node: SyntaxNode, _ folds: Set<Int>, _ ranges: inout [Range<Int>]) {
	297	for section in node.children where section.kind == .section {
	298	guard let heading = section.children.first(where: { $0.kind == .heading }) else { continue }
	299	if folds.contains(heading.range.lowerBound) {
	300	if heading.range.upperBound < section.range.upperBound {
	301	ranges.append(heading.range.upperBound..<section.range.upperBound)
	302	}
	303	} else {
	304	collectHidden(section, folds, &ranges)
	305	}
	306	}
	307	}
	308
	309	/// Start offset of the heading whose line contains `offset`.
	310	public static func heading(containing offset: Int, in tree: OrgTree) -> Int? {
	311	var node = tree.root
	312	while let child = node.children.first(where: { $0.range.contains(offset) }) {
	313	if child.kind == .heading { return child.range.lowerBound }
	314	guard child.kind == .section \|\| child.kind == .zerothSection else { return nil }
	315	node = child
	316	}
	317	return nil
	318	}
	319
	320	/// Start offsets of every heading, for folding everything.
	321	public static func headings(_ tree: OrgTree) -> [Int] {
	322	tree.root.descendants().filter { $0.kind == .heading }.map(\.range.lowerBound)
	323	}
	324	}
	325	```
	326
	327	- [ ] Step 3: Run, build for iOS, commit
	328
	329	Run: `swift test --filter OrgPresentationTests`, then `xcodebuild -scheme OrgPresentation -destination 'generic/platform=iOS' build`.
	330
	331	```bash
	332	git add Package.swift Sources/OrgPresentation Tests/OrgPresentationTests
	333	git commit -m "Add platform-free presentation policy"
	334	```
	335
	336	---
	337
	338	### Task 2: AppKit editor
	339
	340	Files:
	341	- Modify: `Package.swift` (add `OrgEditorAppKit`), `Sources/OrgDocument/ViewState.swift`
	342	- Create: `Sources/OrgEditorAppKit/OrgEditor.swift`, `Sources/OrgEditorAppKit/Theme.swift`
	343	- Test: `Tests/OrgEditorAppKitTests/EditorTests.swift`
	344
	345	Interfaces:
	346	- Consumes: `DocumentState`, `ViewState`, `Saver`, `lineEdits` (OrgDocument); Task 1.
	347	- Produces: `OrgEditor(document:frame:)` with `textView`, `document`, `view`, `onEditTiming`, `makeScrollView()`, `setFolds(_:)`, `toggleFoldAtCaret()`, `toggleAllFolds()`, `save(using:to:)`.
	348
	349	- [ ] Step 1: Make pruning cheap
	350
	351	```diff
	352	@@ -22,11 +22,22 @@ public struct ViewState: Sendable, Equatable {
	353
	354	/// Drops folds that no longer sit at the start of a heading.
	355	public func pruned(to tree: OrgTree) -> ViewState {
	356	- let headings = Set(tree.root.descendants().filter { $0.kind == .heading }.map(\.range.lowerBound))
	357	- return ViewState(selection: selection, folds: folds.intersection(headings))
	358	+ guard !folds.isEmpty else { return self }
	359	+ return ViewState(selection: selection, folds: folds.filter { isHeadingStart($0, tree.root) })
	360	}
	361	}
	362
	363	+/// Descends only through the sections containing `offset`.
	364	+func isHeadingStart(_ offset: Int, _ root: SyntaxNode) -> Bool {
	365	+ var node = root
	366	+ while let child = node.children.first(where: { $0.range.contains(offset) }) {
	367	+ if child.kind == .heading { return child.range.lowerBound == offset }
	368	+ guard child.kind == .section \|\| child.kind == .zerothSection else { return false }
	369	+ node = child
	370	+ }
	371	+ return false
	372	+}
	373	+
	374	/// An offset before an edit stays put; one at the start of a replaced range stays at its start;
	375	/// one inside it, at its end, or at an insertion point moves past the replacement.
	376	func mapOffset(_ offset: Int, _ sortedEdits: [TextEdit]) -> Int {
	377	```
	378
	379	- [ ] Step 2: Write the failing tests
	380
	381	The tests drive a real `NSTextView` in an offscreen window. `RestyleFuzzTests` compares the incrementally styled storage with a fresh editor after every random edit.
	382
	383	```swift
	384	import AppKit
	385	import OrgCore
	386	import OrgDocument
	387	import Testing
	388	@testable import OrgEditorAppKit
	389
	390	/// An editor in an offscreen window, laid out.
	391	@MainActor
	392	final class Harness {
	393	let editor: OrgEditor
	394	let window: NSWindow
	395
	396	init(_ text: String) {
	397	_ = NSApplication.shared
	398	editor = OrgEditor(document: DocumentState(bytes: Array(text.utf8)))
	399	window = NSWindow(contentRect: NSRect(x: 0, y: 0, width: 600, height: 800), styleMask: [.titled], backing: .buffered, defer: false)
	400	window.contentView = editor.makeScrollView()
	401	window.makeFirstResponder(editor.textView)
	402	layout()
	403	}
	404
	405	var textView: NSTextView { editor.textView }
	406	var string: String { textView.string }
	407
	408	func layout() {
	409	let manager = editor.textLayoutManager
	410	manager.ensureLayout(for: manager.documentRange)
	411	}
	412
	413	/// Text of each laid-out paragraph.
	414	var visibleLines: [String] {
	415	layout()
	416	let manager = editor.textLayoutManager
	417	var lines: [String] = []
	418	manager.enumerateTextLayoutFragments(from: manager.documentRange.location, options: [.ensuresLayout]) { fragment in
	419	let content = manager.textContentManager!
	420	let start = content.offset(from: content.documentRange.location, to: fragment.rangeInElement.location)
	421	let end = content.offset(from: content.documentRange.location, to: fragment.rangeInElement.endLocation)
	422	lines.append((self.string as NSString).substring(with: NSRange(location: start, length: end - start)))
	423	return true
	424	}
	425	return lines.filter { !$0.isEmpty }
	426	}
	427
	428	func caret(at offset: Int) {
	429	textView.setSelectedRange(NSRange(location: offset, length: 0))
	430	}
	431
	432	var caret: Int { textView.selectedRange().location }
	433
	434	func offset(of line: String) -> Int {
	435	(string as NSString).range(of: line).location
	436	}
	437
	438	func checkInSync() {
	439	#expect(editor.document.text == string)
	440	#expect(editor.document.tree.green == OrgParser.parse(string).green)
	441	}
	442	}
	443
	444	let outline = "* a\nbody\n** b\nmore\n* c\ntext\n"
	445
	446	@MainActor
	447	struct FoldingTests {
	448	@Test func foldingHidesTheSubtree() {
	449	let h = Harness(outline)
	450	#expect(h.visibleLines == ["* a\n", "body\n", "** b\n", "more\n", "* c\n", "text\n"])
	451	h.caret(at: 1)
	452	#expect(h.editor.toggleFoldAtCaret())
	453	#expect(h.visibleLines == ["* a\n", "* c\n", "text\n"])
	454	h.editor.toggleFoldAtCaret()
	455	#expect(h.visibleLines.count == 6)
	456	}
	457
	458	@Test func tabFoldsOnlyOnHeadings() {
	459	let h = Harness(outline)
	460	h.caret(at: 5)
	461	#expect(!h.editor.toggleFoldAtCaret())
	462	h.textView.doCommand(by: #selector(NSResponder.insertBacktab(_:)))
	463	#expect(h.visibleLines == ["* a\n", "* c\n"])
	464	}
	465
	466	@Test func caretMovesOverFoldedText() {
	467	let h = Harness(outline)
	468	h.caret(at: 1)
	469	h.editor.toggleFoldAtCaret()
	470	h.caret(at: 0)
	471	h.textView.moveDown(nil)
	472	#expect(h.caret >= h.offset(of: "* c") && h.caret < h.offset(of: "text"))
	473	h.caret(at: 3)
	474	h.textView.moveRight(nil)
	475	#expect(h.caret == h.offset(of: "* c"))
	476	h.textView.moveLeft(nil)
	477	#expect(h.caret == 3)
	478	}
	479
	480	@Test func copyingAcrossAFoldIncludesHiddenText() {
	481	let h = Harness(outline)
	482	h.caret(at: 1)
	483	h.editor.toggleFoldAtCaret()
	484	h.textView.setSelectedRange(NSRange(location: 0, length: h.offset(of: "text")))
	485	let pasteboard = NSPasteboard(name: NSPasteboard.Name("orgstar-test-\(UUID().uuidString)"))
	486	defer { pasteboard.releaseGlobally() }
	487	#expect(h.textView.writeSelection(to: pasteboard, types: h.textView.writablePasteboardTypes))
	488	#expect(pasteboard.string(forType: .string) == "* a\nbody\n** b\nmore\n* c\n")
	489	}
	490
	491	@Test func foldsFollowEdits() {
	492	let h = Harness(outline)
	493	h.caret(at: h.offset(of: "* c") + 1)
	494	h.editor.toggleFoldAtCaret()
	495	h.caret(at: 0)
	496	h.textView.insertText("new ", replacementRange: NSRange(location: 2, length: 0))
	497	#expect(h.visibleLines == ["* new a\n", "body\n", "** b\n", "more\n", "* c\n"])
	498	h.checkInSync()
	499	}
	500	}
	501
	502	@MainActor
	503	struct EditingTests {
	504	@Test func typingKeepsTheDocumentInSync() {
	505	let h = Harness(outline)
	506	h.caret(at: h.offset(of: "body") + 4)
	507	h.textView.insertText(" bold", replacementRange: h.textView.selectedRange())
	508	h.textView.insertNewline(nil)
	509	h.textView.insertText("* new heading", replacementRange: h.textView.selectedRange())
	510	h.textView.deleteBackward(nil)
	511	h.checkInSync()
	512	#expect(h.editor.document.isDirty)
	513	}
	514
	515	@Test func inputMethodComposition() {
	516	let h = Harness("* a\n")
	517	h.caret(at: 3)
	518	h.textView.setMarkedText("か", selectedRange: NSRange(location: 1, length: 0), replacementRange: NSRange(location: NSNotFound, length: 0))
	519	#expect(h.textView.hasMarkedText())
	520	h.textView.setMarkedText("かん", selectedRange: NSRange(location: 2, length: 0), replacementRange: NSRange(location: NSNotFound, length: 0))
	521	h.textView.insertText("漢", replacementRange: NSRange(location: NSNotFound, length: 0))
	522	#expect(!h.textView.hasMarkedText())
	523	#expect(h.string == "* a漢\n")
	524	h.checkInSync()
	525	}
	526
	527	@Test func undoKeepsTheDocumentInSync() {
	528	let h = Harness(outline)
	529	h.caret(at: 3)
	530	h.textView.insertText("xyz", replacementRange: h.textView.selectedRange())
	531	h.textView.breakUndoCoalescing()
	532	h.textView.undoManager?.undo()
	533	#expect(h.string == outline)
	534	h.checkInSync()
	535	}
	536
	537	@Test func styling() throws {
	538	let h = Harness("** b\nbody\n")
	539	let storage = try #require(h.textView.textStorage)
	540	#expect(storage.attribute(.foregroundColor, at: 0, effectiveRange: nil) as? NSColor == .clear)
	541	let style = try #require(storage.attribute(.paragraphStyle, at: 6, effectiveRange: nil) as? NSParagraphStyle)
	542	#expect(style.firstLineHeadIndent == 3 * h.editor.theme.column)
	543	h.caret(at: 0)
	544	h.textView.insertText("*", replacementRange: NSRange(location: 0, length: 0))
	545	let deeper = try #require(storage.attribute(.paragraphStyle, at: 7, effectiveRange: nil) as? NSParagraphStyle)
	546	#expect(deeper.firstLineHeadIndent == 4 * h.editor.theme.column)
	547	}
	548
	549	@Test func accessibilityReadsTheWholeText() {
	550	let h = Harness(outline)
	551	h.caret(at: 1)
	552	h.editor.toggleFoldAtCaret()
	553	#expect(h.textView.accessibilityValue() as? String == outline)
	554	h.textView.setSelectedRange(NSRange(location: 0, length: 3))
	555	#expect(h.textView.accessibilitySelectedText() == "* a")
	556	#expect(h.textView.accessibilityLine(for: h.offset(of: "* c")) >= 1)
	557	}
	558
	559	@Test func saveWritesAndClearsDirty() throws {
	560	let folder = FileManager.default.temporaryDirectory.appendingPathComponent("orgstar-\(UUID().uuidString)")
	561	try FileManager.default.createDirectory(at: folder, withIntermediateDirectories: true)
	562	defer { try? FileManager.default.removeItem(at: folder) }
	563	let file = folder.appendingPathComponent("a.org")
	564	try Data(outline.utf8).write(to: file)
	565	let h = Harness(outline)
	566	h.textView.insertText("x", replacementRange: NSRange(location: 0, length: 0))
	567	let saver = Saver(fileSystem: CoordinatedFileSystem(), recovery: FileRecoveryStore(directory: folder.appendingPathComponent("r")))
	568	#expect(try h.editor.save(using: saver, to: file) == .saved)
	569	#expect(!h.editor.document.isDirty)
	570	#expect(try String(contentsOf: file, encoding: .utf8) == "x" + outline)
	571	}
	572	}
	573
	574	@MainActor
	575	struct RestyleTests {
	576	func indent(_ h: Harness, at line: String) -> CGFloat? {
	577	let style = h.textView.textStorage?.attribute(.paragraphStyle, at: h.offset(of: line), effectiveRange: nil) as? NSParagraphStyle
	578	return style.map { $0.firstLineHeadIndent / h.editor.theme.column }
	579	}
	580
	581	@Test func newHeadingReindentsTheLinesItTakesOver() {
	582	let h = Harness("* a\none\ntwo\nthree\n")
	583	h.textView.insertText("** b\n", replacementRange: NSRange(location: h.offset(of: "two"), length: 0))
	584	#expect(indent(h, at: "one") == 2)
	585	#expect(indent(h, at: "three") == 3)
	586	h.checkInSync()
	587	}
	588
	589	@Test func joiningAwayAHeadingReindentsItsBody() {
	590	let h = Harness("* a\none\n** b\ntwo\nthree\n")
	591	h.textView.insertText("", replacementRange: NSRange(location: h.offset(of: "** b") - 1, length: 1))
	592	#expect(indent(h, at: "three") == 2)
	593	h.checkInSync()
	594	}
	595
	596	@Test func typingASpaceAfterAStarMakesAHeading() {
	597	let h = Harness("* a\n*x\nbody\nmore\n")
	598	h.textView.insertText(" ", replacementRange: NSRange(location: h.offset(of: "*x") + 1, length: 0))
	599	#expect(indent(h, at: "more") == 2)
	600	h.checkInSync()
	601	}
	602	}
	603
	604	@MainActor
	605	struct RestyleFuzzTests {
	606	/// After each random edit, the restyled text must equal a fresh editor's full styling. Set
	607	/// `ORGSTAR_RESTYLE_EDITS` and `ORGSTAR_FUZZ_SEED` for longer runs.
	608	@Test func incrementalRestyleEqualsFullRestyle() throws {
	609	let environment = ProcessInfo.processInfo.environment
	610	var state = UInt64(environment["ORGSTAR_FUZZ_SEED"] ?? "") ?? 20261006
	611	let count = Int(environment["ORGSTAR_RESTYLE_EDITS"] ?? "") ?? 300
	612	func next(_ bound: Int) -> Int {
	613	state = state &* 6364136223846793005 &+ 1442695040888963407
	614	return Int((state >> 33) % UInt64(bound))
	615	}
	616	let pieces = ["* ", "** ", "", " ", "\n", "x", "b*", "TODO ", "- ", "\| a \|", "#+begin_src\n", "#+end_src\n", ":PROPERTIES:\n", ":END:\n", "[[l][d]]", "<2026-10-04 Sun>"]
	617	let h = Harness("* a\nbody b\n** b\n- item\nmore\n* c\ntext\n")
	618	for n in 0..<count {
	619	let length = (h.string as NSString).length
	620	let start = next(length + 1)
	621	let end = min(length, start + next(4))
	622	let replacement = next(3) == 0 ? "" : pieces[next(pieces.count)]
	623	h.textView.insertText(replacement, replacementRange: NSRange(location: start, length: end - start))
	624	let fresh = Harness(h.string)
	625	let same = h.textView.textStorage!.isEqual(to: fresh.textView.textStorage!)
	626	#expect(same, "edit \(n): \(start)..<\(end) \(replacement.debugDescription) -> \(h.string.debugDescription)")
	627	if !same { break }
	628	}
	629	h.checkInSync()
	630	}
	631	}
	632	```
	633
	634	- [ ] Step 3: Implement `Theme.swift`
	635
	636	```swift
	637	#if os(macOS)
	638	import AppKit
	639	import OrgPresentation
	640
	641	/// Attributes for each style role. A fixed theme for now; the app's theme settings replace it.
	642	@MainActor
	643	struct Theme {
	644	let font = NSFont.monospacedSystemFont(ofSize: 13, weight: .regular)
	645
	646	var base: [NSAttributedString.Key: Any] {
	647	[.font: font, .foregroundColor: NSColor.textColor]
	648	}
	649
	650	/// Width of one column of the monospaced font.
	651	var column: CGFloat {
	652	("0" as NSString).size(withAttributes: [.font: font]).width
	653	}
	654
	655	func paragraphStyle(firstLine: Int, wrapped: Int) -> NSParagraphStyle {
	656	let style = NSMutableParagraphStyle()
	657	style.firstLineHeadIndent = CGFloat(firstLine) * column
	658	style.headIndent = CGFloat(wrapped) * column
	659	return style
	660	}
	661
	662	func apply(_ role: StyleRole, to storage: NSTextStorage, range: NSRange) {
	663	switch role {
	664	case .heading(let level):
	665	let size = font.pointSize + CGFloat(max(0, 4 - level))
	666	storage.addAttribute(.font, value: NSFont.monospacedSystemFont(ofSize: size, weight: .semibold), range: range)
	667	case .leadingStars:
	668	storage.addAttribute(.foregroundColor, value: NSColor.clear, range: range)
	669	case .todo:
	670	storage.addAttributes([.foregroundColor: NSColor.systemRed, .font: bold(storage, range)], range: range)
	671	case .done:
	672	storage.addAttributes([.foregroundColor: NSColor.systemGreen, .font: bold(storage, range)], range: range)
	673	case .priority:
	674	storage.addAttribute(.foregroundColor, value: NSColor.systemOrange, range: range)
	675	case .tags, .comment, .keyword, .metadata:
	676	storage.addAttribute(.foregroundColor, value: NSColor.secondaryLabelColor, range: range)
	677	case .bold:
	678	storage.addAttribute(.font, value: bold(storage, range), range: range)
	679	case .italic:
	680	storage.addAttribute(.font, value: NSFontManager.shared.convert(currentFont(storage, range), toHaveTrait: .italicFontMask), range: range)
	681	case .underline:
	682	storage.addAttribute(.underlineStyle, value: NSUnderlineStyle.single.rawValue, range: range)
	683	case .strikeThrough:
	684	storage.addAttribute(.strikethroughStyle, value: NSUnderlineStyle.single.rawValue, range: range)
	685	case .verbatim, .code, .inlineSource:
	686	storage.addAttribute(.backgroundColor, value: NSColor.quaternarySystemFill, range: range)
	687	case .markup, .linkMarkup, .blockDelimiter:
	688	storage.addAttribute(.foregroundColor, value: NSColor.tertiaryLabelColor, range: range)
	689	case .link:
	690	storage.addAttributes([.foregroundColor: NSColor.linkColor, .underlineStyle: NSUnderlineStyle.single.rawValue], range: range)
	691	case .timestamp:
	692	storage.addAttribute(.foregroundColor, value: NSColor.systemPurple, range: range)
	693	case .footnote, .cookie, .target, .macro, .latex:
	694	storage.addAttribute(.foregroundColor, value: NSColor.systemTeal, range: range)
	695	case .block:
	696	storage.addAttribute(.backgroundColor, value: NSColor.quaternarySystemFill, range: range)
	697	case .table, .rule:
	698	break
	699	}
	700	}
	701
	702	private func currentFont(_ storage: NSTextStorage, _ range: NSRange) -> NSFont {
	703	storage.attribute(.font, at: range.location, effectiveRange: nil) as? NSFont ?? font
	704	}
	705
	706	private func bold(_ storage: NSTextStorage, _ range: NSRange) -> NSFont {
	707	NSFontManager.shared.convert(currentFont(storage, range), toHaveTrait: .boldFontMask)
	708	}
	709	}
	710	#endif
	711	```
	712
	713	- [ ] Step 4: Implement `OrgEditor.swift`
	714
	715	```swift
	716	#if os(macOS)
	717	import AppKit
	718	import OrgCore
	719	import OrgDocument
	720	import OrgPresentation
	721
	722	/// Hidden ranges, read by TextKit's enumeration callbacks, which may run off the main thread.
	723	final class HiddenRanges: @unchecked Sendable {
	724	private let lock = NSLock()
	725	private var ranges: [Range<Int>] = []
	726
	727	func set(_ new: [Range<Int>]) {
	728	lock.withLock { ranges = new }
	729	}
	730
	731	var all: [Range<Int>] {
	732	lock.withLock { ranges }
	733	}
	734
	735	func covers(_ start: Int, _ end: Int) -> Bool {
	736	lock.withLock { ranges.contains { $0.lowerBound <= start && end <= $0.upperBound } }
	737	}
	738
	739	func containing(_ offset: Int) -> Range<Int>? {
	740	lock.withLock { ranges.first { $0.lowerBound <= offset && offset < $0.upperBound } }
	741	}
	742	}
	743
	744	/// Folded heading starts, read by the layout-fragment callback.
	745	final class FoldedHeadings: @unchecked Sendable {
	746	private let lock = NSLock()
	747	private var starts: Set<Int> = []
	748
	749	func set(_ new: Set<Int>) {
	750	lock.withLock { starts = new }
	751	}
	752
	753	func contains(_ offset: Int) -> Bool {
	754	lock.withLock { starts.contains(offset) }
	755	}
	756	}
	757
	758	/// A TextKit 2 text view over a `DocumentState`. The text storage mirrors the document; every
	759	/// character edit goes through `DocumentState.apply`, and only the affected region is restyled.
	760	@MainActor
	761	public final class OrgEditor: NSObject {
	762	public let textView: NSTextView
	763	public private(set) var document: DocumentState
	764	public private(set) var view = ViewState()
	765	/// Called with the time from a character edit to restyled text.
	766	public var onEditTiming: ((Duration) -> Void)?
	767
	768	let hidden = HiddenRanges()
	769	let folded = FoldedHeadings()
	770	let theme = Theme()
	771	private var isLoading = false
	772	private var previousSelection = 0
	773
	774	public init(document: DocumentState, frame: NSRect = NSRect(x: 0, y: 0, width: 600, height: 800)) {
	775	self.document = document
	776	textView = NSTextView(usingTextLayoutManager: true)
	777	super.init()
	778	textView.frame = frame
	779	textView.isRichText = false
	780	textView.allowsUndo = true
	781	textView.isAutomaticQuoteSubstitutionEnabled = false
	782	textView.isAutomaticDashSubstitutionEnabled = false
	783	textView.isAutomaticTextReplacementEnabled = false
	784	textView.isAutomaticSpellingCorrectionEnabled = false
	785	textView.font = theme.font
	786	textView.typingAttributes = theme.base
	787	textView.isVerticallyResizable = true
	788	textView.autoresizingMask = [.width]
	789	textView.textContainer?.widthTracksTextView = true
	790	textView.delegate = self
	791	textView.textStorage?.delegate = self
	792	textLayoutManager.delegate = self
	793	textContentStorage.delegate = self
	794
	795	isLoading = true
	796	textView.string = document.text
	797	isLoading = false
	798	restyleOutsideEditing(0..<utf16Length)
	799	}
	800
	801	public var textLayoutManager: NSTextLayoutManager { textView.textLayoutManager! }
	802	var textContentStorage: NSTextContentStorage { textLayoutManager.textContentManager as! NSTextContentStorage }
	803	var utf16Length: Int { (textView.string as NSString).length }
	804
	805	/// A scroll view holding the text view, ready for a window.
	806	public func makeScrollView() -> NSScrollView {
	807	let scroll = NSScrollView(frame: textView.frame)
	808	scroll.hasVerticalScroller = true
	809	scroll.documentView = textView
	810	textView.minSize = NSSize(width: 0, height: scroll.contentSize.height)
	811	textView.maxSize = NSSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude)
	812	return scroll
	813	}
	814
	815	// MARK: - Saving
	816
	817	/// Saves through `saver`. When a merge changes the buffer, the text view is reloaded and
	818	/// folds are mapped through the change.
	819	@discardableResult
	820	public func save(using saver: Saver, to url: URL) throws -> SaveOutcome {
	821	let before = document.text
	822	let outcome = try saver.save(&document, to: url)
	823	if document.text != before {
	824	let edits = lineEdits(from: before, to: document.text)
	825	isLoading = true
	826	textView.string = document.text
	827	isLoading = false
	828	restyleOutsideEditing(0..<utf16Length)
	829	setFolds(view.mapped(through: edits).folds)
	830	}
	831	return outcome
	832	}
	833
	834	// MARK: - Folding
	835
	836	public func setFolds(_ folds: Set<Int>) {
	837	view.folds = folds
	838	view = view.pruned(to: document.tree)
	839	folded.set(view.folds)
	840	hidden.set(Presentation.hiddenRanges(document.tree, folds: view.folds))
	841	textLayoutManager.invalidateLayout(for: textLayoutManager.documentRange)
	842	textView.needsDisplay = true
	843	let caret = textView.selectedRange().location
	844	if let range = hidden.containing(caret) { setCaret(range.lowerBound - 1) }
	845	}
	846
	847	/// Folds or unfolds the heading whose line holds the caret. Returns false off a heading.
	848	@discardableResult
	849	public func toggleFoldAtCaret() -> Bool {
	850	guard let heading = Presentation.heading(containing: textView.selectedRange().location, in: document.tree) else { return false }
	851	var folds = view.folds
	852	if folds.contains(heading) { folds.remove(heading) } else { folds.insert(heading) }
	853	setFolds(folds)
	854	return true
	855	}
	856
	857	/// Folds every heading, or unfolds everything if anything is folded.
	858	public func toggleAllFolds() {
	859	setFolds(view.folds.isEmpty ? Set(Presentation.headings(document.tree)) : [])
	860	}
	861
	862	private func setCaret(_ offset: Int) {
	863	let clamped = max(0, min(offset, utf16Length))
	864	previousSelection = clamped
	865	textView.setSelectedRange(NSRange(location: clamped, length: 0))
	866	}
	867
	868	// MARK: - Styling
	869
	870	private func restyleOutsideEditing(_ range: Range<Int>) {
	871	guard let storage = textView.textStorage else { return }
	872	storage.beginEditing()
	873	restyle(range, in: storage)
	874	storage.endEditing()
	875	}
	876
	877	/// Sets attributes for whole lines in `range`. Safe inside `didProcessEditing`, where
	878	/// attribute changes are allowed and characters must not change.
	879	private func restyle(_ range: Range<Int>, in storage: NSTextStorage) {
	880	guard !range.isEmpty else { return }
	881	let whole = NSRange(range)
	882	storage.setAttributes(theme.base, range: whole)
	883	for run in Presentation.indents(document.tree, in: range) {
	884	guard let clipped = clip(run.range, to: range) else { continue }
	885	storage.addAttribute(.paragraphStyle, value: theme.paragraphStyle(firstLine: run.firstLine, wrapped: run.wrapped), range: clipped)
	886	}
	887	for run in Presentation.styles(document.tree, in: range) {
	888	guard let clipped = clip(run.range, to: range) else { continue }
	889	theme.apply(run.role, to: storage, range: clipped)
	890	}
	891	}
	892
	893	private func clip(_ run: Range<Int>, to range: Range<Int>) -> NSRange? {
	894	let clipped = run.clamped(to: range)
	895	return clipped.isEmpty ? nil : NSRange(clipped)
	896	}
	897
	898	/// The region an edit affects in one version of the tree: inside the innermost section
	899	/// holding the edited lines (plus the line after), every element that overlaps them or the
	900	/// line on either side. A changed heading line, or an added or removed heading, widens it
	901	/// to that section's whole own body. Run on the old and the new tree, the union covers
	902	/// elements that grew and elements that shrank.
	903	static func affectedRange(_ tree: OrgTree, _ text: NSString, _ start: Int, _ end: Int, touchedHeadings: Bool) -> Range<Int> {
	904	let lines = text.lineRange(for: NSRange(location: start, length: min(end + 1, text.length) - start))
	905	let lineRange = lines.location..<(lines.location + lines.length)
	906	let around = max(0, lineRange.lowerBound - 1)..<min(text.length, lineRange.upperBound + 1)
	907	var container = tree.root
	908	while let child = container.children.first(where: {
	909	($0.kind == .section \|\| $0.kind == .zerothSection)
	910	&& $0.range.lowerBound <= lineRange.lowerBound && lineRange.upperBound <= $0.range.upperBound
	911	}) {
	912	container = child
	913	}
	914	var lower = lineRange.lowerBound
	915	var upper = lineRange.upperBound
	916	let children = container.children
	917	for child in children where child.range.overlaps(around) {
	918	lower = min(lower, child.range.lowerBound)
	919	upper = max(upper, child.range.upperBound)
	920	}
	921	let heading = children.first { $0.kind == .heading }
	922	if touchedHeadings \|\| heading.map({ $0.range.overlaps(lineRange) }) == true {
	923	lower = min(lower, container.range.lowerBound)
	924	upper = max(upper, children.first { $0.kind == .section }?.range.lowerBound ?? container.range.upperBound)
	925	}
	926	return lower..<min(upper, text.length)
	927	}
	928
	929	// MARK: - Editing
	930
	931	fileprivate func storageEdited(range: NSRange, delta: Int) {
	932	guard !isLoading, let storage = textView.textStorage else { return }
	933	let clock = ContinuousClock()
	934	let start = clock.now
	935	let replacement = (storage.string as NSString).substring(with: range)
	936	let edit = TextEdit(range: range.location..<(range.location + range.length - delta), replacement: replacement)
	937	let oldText = document.text as NSString
	938	let newText = storage.string as NSString
	939	let newEnd = edit.range.lowerBound + replacement.utf16.count
	940	let touchedHeadings = Self.headingLineNear(edit.range.lowerBound, edit.range.upperBound, in: oldText)
	941	\|\| Self.headingLineNear(edit.range.lowerBound, newEnd, in: newText)
	942	let oldAffected = Self.affectedRange(document.tree, oldText, edit.range.lowerBound, edit.range.upperBound, touchedHeadings: touchedHeadings)
	943	do {
	944	try document.apply([edit], baseRevision: document.revision)
	945	} catch {
	946	assertionFailure("text view and document disagree: \(error)")
	947	return
	948	}
	949	let oldHidden = hidden.all
	950	view = view.mapped(through: [edit]).pruned(to: document.tree)
	951	folded.set(view.folds)
	952	hidden.set(Presentation.hiddenRanges(document.tree, folds: view.folds))
	953	let newAffected = Self.affectedRange(document.tree, newText, edit.range.lowerBound, newEnd, touchedHeadings: touchedHeadings)
	954	let delta = edit.replacement.utf16.count - edit.range.count
	955	let oldMapped = oldAffected.lowerBound..<(oldAffected.upperBound >= edit.range.upperBound ? oldAffected.upperBound + delta : newEnd)
	956	restyle(min(oldMapped.lowerBound, newAffected.lowerBound)..<min(max(oldMapped.upperBound, newAffected.upperBound), newText.length), in: storage)
	957	if hidden.all != oldHidden.map({ mapRange($0, through: edit) }) {
	958	textLayoutManager.invalidateLayout(for: textLayoutManager.documentRange)
	959	}
	960	onEditTiming?(clock.now - start)
	961	}
	962
	963	/// Whether a heading line touches `start..<end` or starts right after it, where joining
	964	/// lines could take it away.
	965	static func headingLineNear(_ start: Int, _ end: Int, in text: NSString) -> Bool {
	966	let length = min(end + 1, text.length) - start
	967	guard length >= 0 else { return false }
	968	let lines = text.substring(with: text.lineRange(for: NSRange(location: start, length: length)))
	969	return lines.split(separator: "\n", omittingEmptySubsequences: false).contains { line in
	970	let stars = line.prefix { $0 == "*" }
	971	let after = line.dropFirst(stars.count)
	972	return !stars.isEmpty && (after.isEmpty \|\| after.first == " " \|\| after.first == "\t" \|\| after.first == "\r")
	973	}
	974	}
	975
	976	private func mapRange(_ range: Range<Int>, through edit: TextEdit) -> Range<Int> {
	977	let mapped = ViewState(selection: [range]).mapped(through: [edit]).selection[0]
	978	return mapped
	979	}
	980
	981	/// Keeps the caret out of folded text: moving forward into a fold jumps past it, moving
	982	/// back jumps to the end of the heading line.
	983	fileprivate func selectionChanged() {
	984	let selection = textView.selectedRange()
	985	defer { previousSelection = selection.location }
	986	guard selection.length == 0, let range = hidden.containing(selection.location) else { return }
	987	setCaret(selection.location >= previousSelection ? range.upperBound : range.lowerBound - 1)
	988	}
	989	}
	990
	991	extension OrgEditor: NSTextViewDelegate {
	992	public func textView(_ textView: NSTextView, doCommandBy selector: Selector) -> Bool {
	993	switch selector {
	994	case #selector(NSResponder.insertTab(_:)): return toggleFoldAtCaret()
	995	case #selector(NSResponder.insertBacktab(_:)):
	996	toggleAllFolds()
	997	return true
	998	default: return false
	999	}
	1000	}
	1001
	1002	public func textViewDidChangeSelection(_ notification: Notification) {
	1003	selectionChanged()
	1004	}
	1005	}
	1006
	1007	extension OrgEditor: NSTextStorageDelegate {
	1008	public nonisolated func textStorage(
	1009	_ textStorage: NSTextStorage, didProcessEditing editedMask: NSTextStorageEditActions, range editedRange: NSRange, changeInLength delta: Int
	1010	) {
	1011	guard editedMask.contains(.editedCharacters) else { return }
	1012	MainActor.assumeIsolated { storageEdited(range: editedRange, delta: delta) }
	1013	}
	1014	}
	1015
	1016	extension OrgEditor: NSTextContentStorageDelegate {
	1017	/// Folded text isn't enumerated, so it isn't laid out or drawn.
	1018	public nonisolated func textContentManager(
	1019	_ textContentManager: NSTextContentManager, shouldEnumerate textElement: NSTextElement, options: NSTextContentManager.EnumerationOptions = []
	1020	) -> Bool {
	1021	guard let range = textElement.elementRange else { return true }
	1022	let documentStart = textContentManager.documentRange.location
	1023	let start = textContentManager.offset(from: documentStart, to: range.location)
	1024	let end = textContentManager.offset(from: documentStart, to: range.endLocation)
	1025	return !hidden.covers(start, end)
	1026	}
	1027	}
	1028
	1029	extension OrgEditor: NSTextLayoutManagerDelegate {
	1030	public nonisolated func textLayoutManager(
	1031	_ textLayoutManager: NSTextLayoutManager, textLayoutFragmentFor location: NSTextLocation, in textElement: NSTextElement
	1032	) -> NSTextLayoutFragment {
	1033	let range = textElement.elementRange
	1034	if let range, let manager = textLayoutManager.textContentManager {
	1035	let offset = manager.offset(from: manager.documentRange.location, to: range.location)
	1036	if folded.contains(offset) { return FoldedHeadingFragment(textElement: textElement, range: range) }
	1037	}
	1038	return NSTextLayoutFragment(textElement: textElement, range: range)
	1039	}
	1040	}
	1041
	1042	/// A heading line drawn with an ellipsis after it, like org's folded headings.
	1043	final class FoldedHeadingFragment: NSTextLayoutFragment, @unchecked Sendable {
	1044	override func draw(at point: CGPoint, in context: CGContext) {
	1045	super.draw(at: point, in: context)
	1046	guard let line = textLineFragments.first else { return }
	1047	let bounds = line.typographicBounds
	1048	let ellipsis = NSAttributedString(string: " …", attributes: [
	1049	.font: NSFont.monospacedSystemFont(ofSize: NSFont.systemFontSize, weight: .regular),
	1050	.foregroundColor: NSColor.secondaryLabelColor,
	1051	])
	1052	NSGraphicsContext.saveGraphicsState()
	1053	NSGraphicsContext.current = NSGraphicsContext(cgContext: context, flipped: true)
	1054	ellipsis.draw(at: CGPoint(x: point.x + bounds.maxX, y: point.y + bounds.minY))
	1055	NSGraphicsContext.restoreGraphicsState()
	1056	}
	1057
	1058	override var renderingSurfaceBounds: CGRect {
	1059	super.renderingSurfaceBounds.insetBy(dx: -40, dy: 0).offsetBy(dx: 40, dy: 0)
	1060	}
	1061	}
	1062	#endif
	1063	```
	1064
	1065	- [ ] Step 5: Run, including longer fuzz runs, then commit
	1066
	1067	Run: `swift test`, then `ORGSTAR_RESTYLE_EDITS=1500 ORGSTAR_FUZZ_SEED=<n> swift test --filter RestyleFuzzTests` for several seeds.
	1068
	1069	```bash
	1070	git add Package.swift Sources/OrgDocument/ViewState.swift Sources/OrgEditorAppKit Tests/OrgEditorAppKitTests
	1071	git commit -m "Add TextKit 2 editor with folding and incremental restyle"
	1072	```
	1073
	1074	---
	1075
	1076	### Task 3: Spike app
	1077
	1078	Files:
	1079	- Modify: `Package.swift` (add the `OrgstarSpike` executable)
	1080	- Create: `Sources/OrgstarSpike/main.swift`
	1081
	1082	- [ ] Step 1: Implement
	1083
	1084	```swift
	1085	#if os(macOS)
	1086	import AppKit
	1087	import OrgDocument
	1088	import OrgEditorAppKit
	1089
	1090	/// A throwaway app for trying the editor by hand: `swift run OrgstarSpike path/to/file.org`.
	1091	/// TAB on a heading folds it, Shift-TAB folds everything, ⌘S saves. Edit timings are printed
	1092	/// every 50 edits.
	1093	@MainActor
	1094	final class SpikeDelegate: NSObject, NSApplicationDelegate {
	1095	let url: URL
	1096	var editor: OrgEditor?
	1097	var window: NSWindow?
	1098	var timings: [Duration] = []
	1099
	1100	init(url: URL) {
	1101	self.url = url
	1102	}
	1103
	1104	func applicationDidFinishLaunching(_ notification: Notification) {
	1105	let bytes = (try? [UInt8](Data(contentsOf: url))) ?? []
	1106	let editor = OrgEditor(document: DocumentState(bytes: bytes), frame: NSRect(x: 0, y: 0, width: 900, height: 1000))
	1107	editor.onEditTiming = { [weak self] in self?.record($0) }
	1108	let window = NSWindow(
	1109	contentRect: NSRect(x: 100, y: 100, width: 900, height: 1000),
	1110	styleMask: [.titled, .closable, .resizable, .miniaturizable], backing: .buffered, defer: false
	1111	)
	1112	window.title = url.lastPathComponent
	1113	window.contentView = editor.makeScrollView()
	1114	window.makeKeyAndOrderFront(nil)
	1115	window.makeFirstResponder(editor.textView)
	1116	self.editor = editor
	1117	self.window = window
	1118	buildMenu()
	1119	NSApp.activate()
	1120	}
	1121
	1122	func buildMenu() {
	1123	let main = NSMenu()
	1124	let appItem = NSMenuItem()
	1125	appItem.submenu = NSMenu()
	1126	appItem.submenu?.addItem(withTitle: "Quit", action: #selector(NSApplication.terminate(_:)), keyEquivalent: "q")
	1127	let fileItem = NSMenuItem()
	1128	fileItem.submenu = NSMenu(title: "File")
	1129	fileItem.submenu?.addItem(withTitle: "Save", action: #selector(save), keyEquivalent: "s").target = self
	1130	let editItem = NSMenuItem()
	1131	editItem.submenu = NSMenu(title: "Edit")
	1132	editItem.submenu?.addItem(withTitle: "Undo", action: Selector(("undo:")), keyEquivalent: "z")
	1133	editItem.submenu?.addItem(withTitle: "Redo", action: Selector(("redo:")), keyEquivalent: "Z")
	1134	editItem.submenu?.addItem(withTitle: "Cut", action: #selector(NSText.cut(_:)), keyEquivalent: "x")
	1135	editItem.submenu?.addItem(withTitle: "Copy", action: #selector(NSText.copy(_:)), keyEquivalent: "c")
	1136	editItem.submenu?.addItem(withTitle: "Paste", action: #selector(NSText.paste(_:)), keyEquivalent: "v")
	1137	editItem.submenu?.addItem(withTitle: "Select All", action: #selector(NSText.selectAll(_:)), keyEquivalent: "a")
	1138	[appItem, fileItem, editItem].forEach(main.addItem)
	1139	NSApp.mainMenu = main
	1140	}
	1141
	1142	@objc func save() {
	1143	guard let editor else { return }
	1144	let recovery = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)[0]
	1145	.appendingPathComponent("Orgstar/Recovery")
	1146	let saver = Saver(fileSystem: CoordinatedFileSystem(), recovery: FileRecoveryStore(directory: recovery))
	1147	do {
	1148	print("save:", try editor.save(using: saver, to: url))
	1149	} catch {
	1150	print("save failed:", error)
	1151	}
	1152	}
	1153
	1154	func record(_ duration: Duration) {
	1155	timings.append(duration)
	1156	guard timings.count % 50 == 0 else { return }
	1157	let sorted = timings.sorted()
	1158	print("edits: \(timings.count) p50 \(sorted[sorted.count / 2]) p95 \(sorted[sorted.count * 95 / 100])")
	1159	}
	1160
	1161	func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool { true }
	1162	}
	1163
	1164	guard CommandLine.arguments.count > 1 else {
	1165	print("usage: OrgstarSpike path/to/file.org")
	1166	exit(2)
	1167	}
	1168	let app = NSApplication.shared
	1169	app.setActivationPolicy(.regular)
	1170	let delegate = SpikeDelegate(url: URL(fileURLWithPath: CommandLine.arguments[1]))
	1171	app.delegate = delegate
	1172	app.run()
	1173	#endif
	1174	```
	1175
	1176	- [ ] Step 2: Run by hand, measure, commit
	1177
	1178	Run: `swift run -c release OrgstarSpike <large file>`; type, fold with TAB and Shift-TAB, save with ⌘S, watch the printed p50/p95; then the VoiceOver checklist above.
	1179
	1180	```bash
	1181	git add Package.swift Sources/OrgstarSpike
	1182	git commit -m "Add spike app"
	1183	```