macos: the AppKit shell, its icon, and the offscreen e2e harness

2 files changed, 996 insertions, 151 deletions

diff --git a/src/macos/Sources/AppDelegate.swift b/src/macos/Sources/AppDelegate.swift
index 4df5899c..f5ca4080 100644
--- a/src/macos/Sources/AppDelegate.swift
+++ b/src/macos/Sources/AppDelegate.swift
@@ -1,16 +1,16 @@
 import AppKit
 
 // The macOS host: one window, one view, one core. libpardes owns the state
-// machine, the ptys and every worker thread; this file owns the window and the
-// pump that lets the core move at all.
+// machine, the ptys and every worker thread; this file owns the window, the
+// menu bar, and the pump that lets the core move at all.
 //
 // PardesView translates events and calls pardes_key / pardes_mouse /
 // pardes_scroll itself, but never pardes_tick — the core only queues what it
 // was told and does nothing until it is pumped. Rather than grow the view's
-// delegate a third method for "I just fed the core", the view posts this
-// notification after every input call and we answer it with pump(). The string
-// below is the whole contract with PardesView.swift; keep the two in step.
-private let didInputNotification = Notification.Name("pardesDidInput")
+// delegate a third method for "I just fed the core", the view posts
+// pardesDidInputNotification after every input call and we answer it with
+// pump(). That name is declared once, in PardesView.swift, precisely so the two
+// files cannot drift apart on a string literal.
 
 final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
     private var window: NSWindow!
@@ -20,12 +20,35 @@ final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
     // keys during a fade would leave one 60 Hz chain per keystroke, all of them
     // ticking until the fade ended.
     private var pumpScheduled: Bool = false
+    // The core is a singleton with no "is it alive" query, and Finder can hand
+    // us documents before applicationDidFinishLaunching runs. Every entry point
+    // that would call into libpardes from outside the launch sequence checks
+    // this first; opens that arrive early queue below instead of crashing in a
+    // core that has not been constructed.
+    private var coreIsUp: Bool = false
+    private var pendingOpens: [URL] = []
 
     func applicationDidFinishLaunching(_ notification: Notification) {
+        // Captured before the chdir below, because `pardes ./foo.zig` from a
+        // terminal means foo.zig in the shell's directory, not in $HOME.
+        let launchDirectory = FileManager.default.currentDirectoryPath
+
+        // A bundle launched from Finder, the Dock or `open(1)` inherits cwd `/`
+        // — launchd's, not any shell's — so the first pane's shell would start
+        // at the root of the disk and every relative path the user types would
+        // resolve there. A binary run from a terminal inherits that terminal's
+        // directory, which is already what was meant, so only the `/` case is
+        // corrected: anything else is somebody's deliberate choice.
+        if launchDirectory == "/" {
+            FileManager.default.changeCurrentDirectoryPath(NSHomeDirectory())
+        }
+
+        installMainMenu()
+
         // ponytail: 14pt, fixed. The SDL shell steps its font on Ctrl+/Ctrl-
         // (gui.zig); doing that here means re-measuring the view's metrics and
         // pushing a resize behind it, so it waits until the font has to move.
-        view = PardesView(fontSize: 14)
+        view = PardesView(fontSize: defaultFontSize)
 
         let want = NSSize(width: 1000, height: 700)
         window = NSWindow(
@@ -42,14 +65,40 @@ final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
 
         // Trim the content box down to whole cells: a partial column or row is
         // dead space the core can never draw into.
-        //
-        // ponytail: snapped once, at launch — a live drag lands wherever the
-        // mouse lets go. window.contentResizeIncrements would snap every
-        // resize, at the price of arguing with macOS full-screen tiling.
         window.setContentSize(NSSize(
             width: (want.width / view.cellWidth).rounded(.down) * view.cellWidth,
             height: (want.height / view.cellHeight).rounded(.down) * view.cellHeight))
-        window.center()
+        // Autosave after the snap, never before: on a first run there is no
+        // saved frame and the window must still open at the snapped default,
+        // and registering the name first would have AppKit write the unsnapped
+        // 1000x700 out as the remembered geometry.
+        window.setFrameAutosaveName("pardes")
+        // setFrameAutosaveName only arms the saving half; the restore is this
+        // call, and it reports whether there was anything to restore. Both must
+        // happen before pardes_init, because the grid we boot the core with has
+        // to be the grid the window actually ends up at.
+        if !window.setFrameUsingName("pardes") {
+            window.center()
+        }
+        // Resize in whole cells. Increments are measured from the window's
+        // current size rather than from zero, which is why the snap above still
+        // matters: without it every drag would land a half-column short of the
+        // frame, and the view would draw a strip it can never put a glyph in.
+        window.contentResizeIncrements = NSSize(width: view.cellWidth, height: view.cellHeight)
+        // One core per process, so a second tab would be an empty window with
+        // no grid behind it. macOS offers tabs on any titled resizable window
+        // unless told otherwise.
+        window.tabbingMode = .disallowed
+        // The same constant PardesView paints as defaultBG. Two places name it
+        // because two different things draw: the view fills its own bounds, and
+        // AppKit fills the titlebar and every pixel of a live resize the view
+        // has not caught up with yet — without this that gap flashes white on
+        // every drag. The day the core exposes its theme background over the
+        // ABI, both should read it instead of agreeing by hand.
+        window.backgroundColor = NSColor(srgbRed: 0x12 / 255, green: 0x12 / 255, blue: 0x12 / 255, alpha: 1)
+        // A dark window with a light-mode titlebar reads as a bug. This also
+        // gets the traffic-light glyphs and the resize cursor right.
+        window.appearance = NSAppearance(named: .darkAqua)
         // On screen before pardes_init, so that the backingScaleFactor read
         // when seeding the cell metrics below is the one of the screen the
         // window actually landed on. Drawing before the core exists costs an
@@ -60,14 +109,10 @@ final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
         // own, but "may" is not something to bet every keystroke on, and there
         // is no click-to-focus path here that would recover it.
         window.makeFirstResponder(view)
-        // ponytail: no main menu, so no Cmd+Q — the close button and the core's
-        // Exit builtin are the two ways out. An NSMenu is ten lines, but the
-        // moment one exists it also has to decide which Cmd keys the core is
-        // allowed to see, and that is a real decision, not boilerplate.
-        //
-        // UNVERIFIED: activate(ignoringOtherApps:) is deprecated on the 14 SDK
-        // in favour of activate(), which does not exist at our 13.0 deployment
-        // target. Expect a deprecation warning, not an error.
+        // activate(ignoringOtherApps:) is deprecated in favour of activate() on
+        // the 14 SDK, but activate() does not exist at our 13.0 deployment
+        // target and the deprecation does not fire below it. This is the call
+        // to change the day macos_min_version reaches 14.
         NSApp.activate(ignoringOtherApps: true)
 
         var runtime = pardes_runtime_s(
@@ -104,13 +149,14 @@ final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
             // would call pardes_deinit on a core that never came up.
             exit(1)
         }
+        coreIsUp = true
 
         // Only now, after init. setContentSize above resized the view, and a
         // pardesViewDidResize landing before pardes_init would have pushed a
         // resize into a core that did not exist yet.
         view.delegate = self
         NotificationCenter.default.addObserver(
-            self, selector: #selector(inputArrived(_:)), name: didInputNotification, object: nil)
+            self, selector: #selector(inputArrived(_:)), name: pardesDidInputNotification, object: nil)
 
         // pardes_init takes no cell metrics, so the core's PDF placement would
         // have none until the user first dragged the window. This seeds them,
@@ -118,6 +164,236 @@ final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
         // core compares the effective pixel viewport, not the resize event, so
         // duplicate SIGWINCH-shaped notifications are already a no-op.
         pardesViewDidResize(view)
+
+        // Positional paths, after the first frame's worth of state exists.
+        // Anything starting with `-` is skipped rather than opened: the core
+        // has no flags yet, and Finder itself passes `-psn_0_...` on some
+        // launch paths, which would otherwise become a Look for a file that
+        // does not exist.
+        for argument in CommandLine.arguments.dropFirst() where !argument.hasPrefix("-") {
+            look(absolutePath(of: argument, relativeTo: launchDirectory))
+        }
+
+        // Documents that Finder handed us before the core existed.
+        let queued = pendingOpens
+        pendingOpens = []
+        for url in queued {
+            look(url.path)
+        }
+    }
+
+    // Finder double-click, Dock drop, `open -a pardes file`, and "Open With".
+    // The URL-array form rather than application(_:openFile:), which has been
+    // deprecated since 10.13 and only ever reports one path at a time.
+    func application(_ application: NSApplication, open urls: [URL]) {
+        // A non-file URL would arrive here only through a URL scheme we do not
+        // register, but Look wants a path and would treat the scheme prefix as
+        // part of one.
+        let files = urls.filter { $0.isFileURL }
+        guard coreIsUp else {
+            // Finder sends these between applicationWillFinishLaunching and
+            // applicationDidFinishLaunching, so they arrive before the core is
+            // constructed and are replayed at the end of launch. They land
+            // after the argv paths, which costs nothing: each path is an
+            // independent Look and only the last one takes focus.
+            pendingOpens.append(contentsOf: files)
+            return
+        }
+        for url in files {
+            look(url.path)
+        }
+    }
+
+    // ---------------------------------------------------------------- menu
+
+    // Built in code rather than loaded from a nib. There is no Xcode project
+    // here (see docs/macos.md), so a MainMenu.xib would be a binary blob nobody
+    // in this tree can edit; the menu is thirty lines of Swift instead.
+    //
+    // Every item that reaches the core goes through run(), which is
+    // pardes_command — the core's own `command` event, the same channel a
+    // pardes nested inside another one speaks over. So a menu item is exactly
+    // the text you could have typed into a tag and executed, and there is no
+    // second vocabulary to keep in step with builtins.zig.
+    //
+    // The cost of having a menu at all is that these chords are now the menu's
+    // and the core can never see them: Cmd+Q, Cmd+H, Opt+Cmd+H, Cmd+O, Cmd+N,
+    // Cmd+S, Cmd+W, Cmd+V, Cmd+M and Cmd+?. AppKit offers a key equivalent to
+    // the main menu before the event ever reaches the key window. Every other
+    // Cmd chord still dies in PardesView, which swallows them because the ABI's
+    // modifier mask has ctrl, alt and shift and no super bit — a Cmd chord
+    // handed to the core would arrive as its unmodified letter and type itself
+    // into the buffer.
+    private func installMainMenu() {
+        let appName = ProcessInfo.processInfo.processName
+        let main = NSMenu()
+
+        // AppKit treats the first top-level item as the application menu
+        // whatever it is titled, and substitutes the bundle name in bold.
+        let app = submenu(appName, of: main)
+        app.addItem(withTitle: "About \(appName)",
+                    action: #selector(NSApplication.orderFrontStandardAboutPanel(_:)),
+                    keyEquivalent: "")
+        app.addItem(.separator())
+        app.addItem(withTitle: "Hide \(appName)",
+                    action: #selector(NSApplication.hide(_:)), keyEquivalent: "h")
+        let hideOthers = app.addItem(withTitle: "Hide Others",
+                                     action: #selector(NSApplication.hideOtherApplications(_:)),
+                                     keyEquivalent: "h")
+        hideOthers.keyEquivalentModifierMask = [.command, .option]
+        app.addItem(withTitle: "Show All",
+                    action: #selector(NSApplication.unhideAllApplications(_:)), keyEquivalent: "")
+        app.addItem(.separator())
+        app.addItem(withTitle: "Quit \(appName)",
+                    action: #selector(NSApplication.terminate(_:)), keyEquivalent: "q")
+
+        let file = submenu("File", of: main)
+        file.addItem(command("Open\u{2026}", #selector(menuOpen(_:)), "o"))
+        file.addItem(command("New", #selector(menuNew(_:)), "n"))
+        file.addItem(command("Save", #selector(menuSave(_:)), "s"))
+        file.addItem(.separator())
+        // performClose: goes to the key window through the responder chain, so
+        // it keeps working if this app ever grows a panel.
+        file.addItem(withTitle: "Close Window",
+                     action: #selector(NSWindow.performClose(_:)), keyEquivalent: "w")
+
+        let edit = submenu("Edit", of: main)
+        // Paste and nothing else. Copy, Cut, Undo and Select All have no
+        // builtin behind them — the core yanks into the clipboard on its own
+        // selection gestures and has no undo command to call — and a greyed or
+        // silently dead menu item teaches the user the menu lies. When the core
+        // grows those commands they belong here, spelled as run("...") like
+        // everything else.
+        edit.addItem(command("Paste", #selector(menuPaste(_:)), "v"))
+
+        // The only menu whose items are not core commands: the font size is a
+        // property of this shell and nothing else. `Font` picks the FACE and
+        // lives in the topbar with the other builtins; the size is where the
+        // window is, so it is where macOS keeps it.
+        let viewMenu = submenu("View", of: main)
+        // Cmd+= rather than Cmd++: the key is unshifted `=` on every layout
+        // that has a `+` above it, and AppKit matches the character, not the
+        // engraving. The item is titled with the plus users look for.
+        viewMenu.addItem(command("Zoom In", #selector(menuZoomIn(_:)), "="))
+        viewMenu.addItem(command("Zoom Out", #selector(menuZoomOut(_:)), "-"))
+        viewMenu.addItem(command("Actual Size", #selector(menuZoomReset(_:)), "0"))
+
+        let windowMenu = submenu("Window", of: main)
+        windowMenu.addItem(withTitle: "Minimize",
+                           action: #selector(NSWindow.performMiniaturize(_:)), keyEquivalent: "m")
+        windowMenu.addItem(withTitle: "Zoom", action: #selector(NSWindow.performZoom(_:)), keyEquivalent: "")
+
+        let help = submenu("Help", of: main)
+        // Cmd+? is the system-wide help chord; AppKit draws it as the shift of
+        // Cmd+/ without being told about the shift.
+        help.addItem(command("\(appName) Help", #selector(menuHelp(_:)), "?"))
+        help.addItem(command("Tutorial", #selector(menuTutor(_:)), ""))
+
+        NSApp.mainMenu = main
+        // Handing AppKit these two makes it keep the window list up to date and
+        // put the Help search field at the top of the Help menu. Both must come
+        // after mainMenu is assigned, or AppKit has nothing to attach them to.
+        NSApp.windowsMenu = windowMenu
+        NSApp.helpMenu = help
+    }
+
+    private func submenu(_ title: String, of parent: NSMenu) -> NSMenu {
+        let holder = NSMenuItem(title: title, action: nil, keyEquivalent: "")
+        // The submenu's own title is what AppKit shows in the menu bar for the
+        // Window and Help menus, which it looks up by title rather than by the
+        // item that holds them.
+        let menu = NSMenu(title: title)
+        holder.submenu = menu
+        parent.addItem(holder)
+        return menu
+    }
+
+    // An item that runs one of our own actions. Explicitly targeted at self
+    // rather than left to the responder chain: PardesView is the first
+    // responder and answers none of these, and an untargeted item that finds no
+    // handler renders greyed out.
+    private func command(_ title: String, _ action: Selector, _ key: String) -> NSMenuItem {
+        let item = NSMenuItem(title: title, action: action, keyEquivalent: key)
+        item.target = self
+        return item
+    }
+
+    @objc private func menuOpen(_ sender: Any?) {
+        let panel = NSOpenPanel()
+        panel.canChooseFiles = true
+        // Directories are first-class Look targets — the core opens one as a
+        // directory pane, which is how you navigate in acme — so refusing them
+        // here would hide half of what Look does.
+        panel.canChooseDirectories = true
+        panel.allowsMultipleSelection = true
+        panel.resolvesAliases = true
+        guard panel.runModal() == .OK else { return }
+        for url in panel.urls where url.isFileURL {
+            look(url.path)
+        }
+    }
+
+    @objc private func menuNew(_ sender: Any?) { run("New") }
+    @objc private func menuSave(_ sender: Any?) { run("Save") }
+    @objc private func menuHelp(_ sender: Any?) { run("Help") }
+    @objc private func menuTutor(_ sender: Any?) { run("Tutor") }
+
+    // Deliberately the view's paste path and not a second one: Cmd+V from the
+    // menu and Cmd+V in the view must put the same bytes in through
+    // pardes_paste, or the two would diverge the first time either grows a
+    // filter.
+    @objc private func menuPaste(_ sender: Any?) {
+        guard coreIsUp else { return }
+        pardesViewRequestsPaste(view)
+    }
+
+    // Zoom does not go through the core at all: it changes the cell, the view
+    // reports the new grid, and the core reflows to it exactly as it does for
+    // a window drag. Guarded on coreIsUp only because the resize callback it
+    // triggers calls into libpardes.
+    @objc private func menuZoomIn(_ sender: Any?) {
+        guard coreIsUp else { return }
+        view.zoom(by: 1)
+    }
+
+    @objc private func menuZoomOut(_ sender: Any?) {
+        guard coreIsUp else { return }
+        view.zoom(by: -1)
+    }
+
+    @objc private func menuZoomReset(_ sender: Any?) {
+        guard coreIsUp else { return }
+        view.zoomReset()
+    }
+
+    // ---------------------------------------------------------------- core
+
+    // One builtin command line, run as if it had been typed into a tag and
+    // executed. `command` is bridged to a temporary NUL-terminated UTF-8 buffer
+    // that lives exactly as long as the call, which is exactly as long as the
+    // core borrows it.
+    private func run(_ command: String) {
+        guard coreIsUp else { return }
+        pardes_command(command, command.utf8.count)
+        pump()
+    }
+
+    // Look's operand is the whole tail of the line (executeBuiltinLine in
+    // src/pardes.zig splits on the first space and trims the rest), so a path
+    // with spaces in it needs no quoting and must not get any — quotes would
+    // become part of the filename.
+    private func look(_ path: String) { run("Look \(path)") }
+
+    // argv paths are whatever the shell handed us. The core resolves a relative
+    // Look against the pane's directory, not the process's, so `pardes
+    // ./foo.zig` would open the wrong foo.zig — or nothing — unless it is made
+    // absolute here against the directory the process was launched from.
+    private func absolutePath(of argument: String, relativeTo directory: String) -> String {
+        let expanded = (argument as NSString).expandingTildeInPath
+        guard !(expanded as NSString).isAbsolutePath else {
+            return (expanded as NSString).standardizingPath
+        }
+        return ((directory as NSString).appendingPathComponent(expanded) as NSString).standardizingPath
     }
 
     @objc private func inputArrived(_ notification: Notification) {
@@ -128,7 +404,49 @@ final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
     // the effects the core queued, so nothing the user did takes hold until it
     // runs.
     private func pump() {
-        if pardes_tick() { view.needsDisplay = true }
+        // Unconditionally dirty, and NOT `if pardes_tick()`. That return value
+        // answers "did I do any IO" — it is true when a pty produced bytes or
+        // an effect was performed, and false for everything the core changes on
+        // its own. A cursor moved with j, a selection, a mode change and a
+        // scroll all queue nothing and perform nothing, so gating the repaint
+        // on it leaves the screen showing the state before the keystroke until
+        // some unrelated event happens to force a frame. Measured: four `j`
+        // presses in a file pane produced a byte-identical screenshot.
+        //
+        // The waste is bounded and small. AppKit coalesces needsDisplay within
+        // a runloop pass, so a burst of pty output is still one frame, and an
+        // idle wakeup cannot happen — a reader only wakes the host after it has
+        // read bytes.
+        _ = pardes_tick()
+        view.needsDisplay = true
+
+        // Two verbs, two patterns, because they are two different answers:
+        // Exec did something, so it gets .generic, the definite tap of a
+        // committed action; Look went somewhere, so it gets .alignment, the
+        // lighter detent AppKit uses when a dragged guide snaps into place.
+        // Same distinction the core draws in Haptic (src/pardes.zig).
+        //
+        // No capability check on purpose. perform() is a silent no-op on a Mac
+        // with no Force Touch trackpad and when the user has turned feedback
+        // off in System Settings, so a check here would only be a second place
+        // to get the answer wrong — and it would be wrong the moment an
+        // external trackpad is plugged in mid-session.
+        let pulse = pardes_take_haptic()
+        if pulse == PARDES_HAPTIC_EXEC {
+            NSHapticFeedbackManager.defaultPerformer.perform(.generic, performanceTime: .now)
+        } else if pulse == PARDES_HAPTIC_LOOK {
+            NSHapticFeedbackManager.defaultPerformer.perform(.alignment, performanceTime: .now)
+        }
+
+        // Beside the haptic, and for the same reason: the `Font` builtin ran
+        // synchronously inside whatever input reached the core, so its answer
+        // is already waiting by the time the tick returns. The view re-measures
+        // and calls back through pardesViewDidResize, so the grid the core is
+        // holding follows the cell that just changed size.
+        if let wanted = pardes_font_take() {
+            view.adoptFont(path: String(cString: wanted))
+        }
+
         if pardes_should_quit() {
             NSApp.terminate(nil)
             return
@@ -173,6 +491,15 @@ final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
         return true
     }
 
+    // Nothing in this app's UI state can be restored: the window is one view
+    // over a core that has to replay its own session, and the frame is already
+    // handled by setFrameAutosaveName. Answering true opts into the secure
+    // coder AppKit wants; leaving the method out makes macOS 14 and later log a
+    // deprecation warning on every launch.
+    func applicationSupportsSecureRestorableState(_ app: NSApplication) -> Bool {
+        return true
+    }
+
     func applicationWillTerminate(_ notification: Notification) {
         pardes_deinit()
     }
diff --git a/src/macos/Sources/PardesView.swift b/src/macos/Sources/PardesView.swift
index 2dfa4305..c7152bd3 100644
--- a/src/macos/Sources/PardesView.swift
+++ b/src/macos/Sources/PardesView.swift
@@ -4,7 +4,17 @@
 // This file keeps no model of the screen. The core owns the grid and hands it
 // over whole through src/macos/pardes.h, so everything here is translation, and
 // the only state worth holding is the font metrics — which are expensive to
-// measure and never change.
+// measure and never change — plus the two things a gesture needs remembered
+// between events: which button a click started with, and how hard it is being
+// pressed.
+//
+// Every NSEvent override decodes and then calls one of the post-decode entry
+// points below (press/release/drag/click/scroll/rotate/typeKey). That split is
+// not decoration: NSTouch, pressure stages and rotation have no public
+// constructors, so a test can never synthesize them, and the only way the
+// trackpad behaviour is reachable by anything but a finger is for the decision
+// to live one call below the event. test/macos_e2e.swift drives exactly those
+// entry points.
 //
 // Every C constant below is wrapped in an explicit conversion (UInt16(...),
 // UInt32(...)) rather than used bare. A macro's imported Swift type is decided
@@ -13,18 +23,65 @@
 import AppKit
 import CoreText
 
+/// Posted after every call this view makes into the core, and answered by
+/// AppDelegate.pump(). The core only queues what it was told and does nothing
+/// until it is pumped, so an input without one of these is an input that
+/// visibly did nothing. Declared here, where the posts are.
+let pardesDidInputNotification = Notification.Name("pardesDidInput")
+
+/// A cell, already clamped to the frame the core last rendered.
+struct GridPoint {
+    var col: UInt16
+    var row: UInt16
+}
+
 protocol PardesViewDelegate: AnyObject {
     func pardesViewDidResize(_ view: PardesView)
     func pardesViewRequestsPaste(_ view: PardesView)
 }
 
+/// What a click means, from the fingers resting on the trackpad and the button
+/// stream AppKit chose to deliver it on. Pure on purpose: NSTouch cannot be
+/// constructed, so this is the part of the gesture a test can reach.
+///
+/// acme's three buttons are the whole vocabulary — 1 selects, 2 executes,
+/// 3 looks — and a trackpad has one surface. Two fingers is the gesture macOS
+/// itself spells "secondary", so it is Look; three is the one left over, so it
+/// is Exec, the heavier verb, which is also what a deep press means.
+///
+/// The finger count has to win over the stream, and that is not a preference.
+/// macOS's secondary click is "click or tap with TWO OR MORE fingers": with it
+/// on, a three-finger click is delivered as rightMouseDown exactly like a
+/// two-finger one, and a view that trusts the stream cannot tell them apart —
+/// three fingers silently did Look. Measured on real hardware, which is the
+/// only way this was ever going to be found: `rightMouseDown: resting=3`.
+///
+/// So the stream is only the fallback, for when there are no fingers to count:
+/// a real mouse's right button is Look and its middle button is Exec, and both
+/// arrive with an empty touch set.
+enum Trackpad {
+    static func button(stream: pardes_mouse_button_e, fingers: Int) -> pardes_mouse_button_e {
+        switch fingers {
+        case 2: return PARDES_MOUSE_RIGHT
+        case 3...: return PARDES_MOUSE_MIDDLE
+        // One finger, or none to count: the stream is the answer. A trackpad
+        // single click comes in on the left stream and stays left; a real
+        // mouse's right and middle buttons keep their acme meanings.
+        default: return stream
+        }
+    }
+
+    /// A force click is a deliberate second gesture on top of an ordinary one,
+    /// so it gets the verb that does something rather than the one that
+    /// navigates.
+    static let forceClickButton: pardes_mouse_button_e = PARDES_MOUSE_MIDDLE
+}
+
 // Matches bg_default/fg_default in src/gui/gui.zig and DEFAULT_FG/DEFAULT_BG in
 // src/web/app.mjs. Three shells render the same core; if these drift, comparing
 // a screenshot across backends stops meaning anything.
-private let defaultFG: UInt32 = 0xCC_CC_CC
-private let defaultBG: UInt32 = 0x12_12_12
-
-private let inputNotification = Notification.Name("pardesDidInput")
+let pardesDefaultFG: UInt32 = 0xCC_CC_CC
+let pardesDefaultBG: UInt32 = 0x12_12_12
 
 // UNVERIFIED: kCTFontAttributeName bridged through NSAttributedString.Key. It is
 // the same string as .font, but spelling the CoreText key means the value stays
@@ -60,6 +117,16 @@ private func decodeColor(_ encoded: UInt32, _ fallback: UInt32) -> UInt32 {
     return encoded & UInt32(PARDES_COLOR_RGB_MASK)
 }
 
+/// The four faces, indexed by the two attribute bits that pick one. Also the
+/// glyph cache's first key, which is why it is an ordinal and not four fields.
+private enum Face: Int, CaseIterable {
+    case regular = 0, bold = 1, italic = 2, boldItalic = 3
+
+    init(bold: Bool, italic: Bool) {
+        self = Face(rawValue: (bold ? 1 : 0) | (italic ? 2 : 0))!
+    }
+}
+
 /// `block` means the filled cursor sits on this cell.
 private func resolve(
     _ cell: pardes_cell_s,
@@ -68,10 +135,12 @@ private func resolve(
     // The core never painted this cell, which is most of the screen most of the
     // time, so this branch is the one that has to stay cheap.
     if cell.flags & UInt8(PARDES_CELL_DEFAULT) != 0 {
-        return block ? (defaultBG, defaultFG, 1, false) : (defaultFG, defaultBG, 1, false)
+        return block
+            ? (pardesDefaultBG, pardesDefaultFG, 1, false)
+            : (pardesDefaultFG, pardesDefaultBG, 1, false)
     }
-    var fg = decodeColor(cell.fg, defaultFG)
-    var bg = decodeColor(cell.bg, defaultBG)
+    var fg = decodeColor(cell.fg, pardesDefaultFG)
+    var bg = decodeColor(cell.bg, pardesDefaultBG)
     // The block cursor is a second reverse, so a cell that is already reversed
     // cancels back to normal underneath it. Same rule as emitInstance in
     // src/gui/gui.zig; the two must not drift.
@@ -97,6 +166,113 @@ private func advance(_ font: CTFont, _ character: UniChar) -> CGFloat {
     return size.width
 }
 
+/// The size the window opens at and Cmd+0 returns to. Named here rather than
+/// passed in because zoomReset has to know it too, and two spellings of one
+/// number is how "actual size" stops being the size it actually opened at.
+let defaultFontSize: CGFloat = 14
+
+/// Everything that changes when the face or its size does, in one value so
+/// that changing either is one assignment and cannot leave half the numbers
+/// describing the old font.
+///
+/// Built at init and again for a `Font` command or a zoom. The glyph caches
+/// belong here for the same reason: a CGGlyph is an index into a particular
+/// face, so carrying one across a font change draws the wrong character
+/// rather than none.
+private struct Metrics {
+    let fonts: [CTFont]
+    let ascent: CGFloat
+    let cellWidth: CGFloat
+    let cellHeight: CGFloat
+    let ruleThickness: CGFloat
+    let underlineOffset: CGFloat
+    /// ASCII is very nearly the whole screen, so its glyphs are resolved once
+    /// per face here and never looked up again.
+    let asciiGlyphs: [[CGGlyph]]
+
+    init(size: CGFloat, path: String?) {
+        let face = Metrics.face(size: size, path: path)
+
+        // UNVERIFIED: CTFontSymbolicTraits member spelling (.traitBold/.traitItalic).
+        // A face with no italic cut returns nil here, hence the fallback to `face`.
+        func variant(_ traits: CTFontSymbolicTraits) -> CTFont {
+            CTFontCreateCopyWithSymbolicTraits(face, size, nil, traits, traits) ?? face
+        }
+        let faces = [face, variant(.traitBold), variant(.traitItalic), variant([.traitBold, .traitItalic])]
+
+        // Whole points, rounded UP. A fractional cell width puts every column
+        // boundary on a fraction of a pixel, and with antialiasing off — which
+        // the background pass needs, or touching fills seam — the rounding
+        // wobbles by a pixel from column to column. On a screen made of tag
+        // bars and selections that stripe is visible. Rounding up rather than
+        // to nearest because down can clip a glyph, and a slightly airy grid is
+        // not a bug.
+        fonts = faces
+        ascent = CTFontGetAscent(face)
+        cellWidth = max(1, advance(face, 0x4D).rounded(.up))
+        cellHeight = max(1, (CTFontGetAscent(face) + CTFontGetDescent(face) + CTFontGetLeading(face)).rounded(.up))
+        ruleThickness = max(1, CTFontGetUnderlineThickness(face))
+        underlineOffset = CTFontGetUnderlinePosition(face)
+        asciiGlyphs = faces.map { font in
+            var chars = Array(UniChar(0)..<UniChar(128))
+            var glyphs = [CGGlyph](repeating: 0, count: 128)
+            _ = CTFontGetGlyphsForCharacters(font, &chars, &glyphs, 128)
+            return glyphs
+        }
+    }
+
+    /// The regular cut to build the other three from: the file the core asked
+    /// for, or the system monospace face when it asked for nothing — or when
+    /// what it asked for turned out not to be wearable.
+    private static func face(size: CGFloat, path: String?) -> CTFont {
+        if let path, let picked = Metrics.fromFile(path, size) { return picked }
+        let system = NSFont.monospacedSystemFont(ofSize: size, weight: .regular)
+        // Through the descriptor, not through CTFontCreateWithName(fontName):
+        // the system monospace face has a dot-prefixed internal name that a
+        // by-name lookup can miss entirely, and NSFontDescriptor is toll-free
+        // bridged, so this cannot resolve to a different font than AppKit just
+        // handed us.
+        let face = CTFontCreateWithFontDescriptor(system.fontDescriptor as CTFontDescriptor, size, nil)
+        // The whole layout is a fixed grid, so a proportional face is not a
+        // cosmetic problem, it is a broken screen. "M" and "i" disagreeing on
+        // advance is the cheapest possible proof that we got one.
+        return Metrics.isFixedPitch(face) ? face : CTFontCreateWithName("Menlo" as CFString, size, nil)
+    }
+
+    /// A face out of a font FILE, which is what the core hands over — it found
+    /// the path by walking the font directories itself, so nothing here asks
+    /// CoreText to resolve a name that a different shell might resolve
+    /// differently.
+    ///
+    /// Nil rather than a substitute for anything wrong with the file, because
+    /// the caller's fallback is the face already on screen: a font that cannot
+    /// be measured would otherwise leave a terminal with no way back out.
+    private static func fromFile(_ path: String, _ size: CGFloat) -> CTFont? {
+        let url = URL(fileURLWithPath: path) as CFURL
+        guard let descriptors = CTFontManagerCreateFontDescriptorsFromURL(url) as? [CTFontDescriptor],
+              !descriptors.isEmpty else { return nil }
+        // A .ttc holds a family's four cuts in one file. Take the one with
+        // neither trait set — the regular — because the bold and italic ones
+        // are derived from it below; falling back to the first face keeps a
+        // collection whose cuts are all styled from being unusable.
+        let plain = descriptors.first { descriptor in
+            let traits = CTFontDescriptorCopyAttribute(descriptor, kCTFontTraitsAttribute) as? [CFString: Any]
+            let symbolic = (traits?[kCTFontSymbolicTrait] as? UInt32) ?? 0
+            return symbolic & UInt32(CTFontSymbolicTraits.traitBold.rawValue | CTFontSymbolicTraits.traitItalic.rawValue) == 0
+        }
+        let face = CTFontCreateWithFontDescriptor(plain ?? descriptors[0], size, nil)
+        // The core already filtered for fixed pitch by reading the file's own
+        // advances. This is the same question asked of the face CoreText
+        // actually built, which is the one that will be drawn with.
+        return Metrics.isFixedPitch(face) ? face : nil
+    }
+
+    private static func isFixedPitch(_ face: CTFont) -> Bool {
+        let em = advance(face, 0x4D)
+        return em > 0 && abs(em - advance(face, 0x69)) <= 0.01
+    }
+}
+
 private func modifiers(_ flags: NSEvent.ModifierFlags) -> UInt32 {
     var mods: UInt32 = 0
     if flags.contains(.control) { mods |= UInt32(PARDES_MOD_CTRL) }
@@ -106,59 +282,135 @@ private func modifiers(_ flags: NSEvent.ModifierFlags) -> UInt32 {
 }
 
 final class PardesView: NSView {
-    let cellWidth: CGFloat
-    let cellHeight: CGFloat
     weak var delegate: PardesViewDelegate?
 
-    private let regular: CTFont
-    private let bold: CTFont
-    private let italic: CTFont
-    private let boldItalic: CTFont
-    private let ascent: CGFloat
-    private let ruleThickness: CGFloat
-    private let underlineOffset: CGFloat
+    // The face and the numbers off it, replaced whole by `wear`.
+    private var metrics: Metrics
+    /// What `metrics` was built from, so a zoom keeps the face and a font
+    /// change keeps the size.
+    private var fontSize: CGFloat
+    private var fontPath: String?
+
+    var cellWidth: CGFloat { metrics.cellWidth }
+    var cellHeight: CGFloat { metrics.cellHeight }
+
+    // Glyphs the ASCII table above did not answer for. A stored 0 is .notdef,
+    // meaning "this face does not have it", which is a cache hit too — the
+    // CTLine fallback below is far more expensive than the lookup it would
+    // repeat. Keyed by face and codepoint, and thrown away with the face.
+    private var glyphCache: [UInt32: CGGlyph] = [:]
+    // Scratch for one batched run of glyphs. Held rather than made per row so a
+    // full redraw does not allocate 24 times.
+    private var runGlyphs: [CGGlyph] = []
+    private var runPositions: [CGPoint] = []
+
     private var reportedCols: UInt16 = 0
     private var reportedRows: UInt16 = 0
 
-    init(fontSize: CGFloat) {
-        let system = NSFont.monospacedSystemFont(ofSize: fontSize, weight: .regular)
-        var face = CTFontCreateWithName(system.fontName as CFString, fontSize, nil)
-        // The whole layout is a fixed grid, so a proportional face is not a
-        // cosmetic problem, it is a broken screen. Resolving the system monospace
-        // font by name is a lookup that can miss; "M" and "i" disagreeing on
-        // advance is the cheapest possible proof that it did.
-        let em = advance(face, 0x4D)
-        if em <= 0 || abs(em - advance(face, 0x69)) > 0.01 {
-            face = CTFontCreateWithName("Menlo" as CFString, fontSize, nil)
-        }
+    // The button a left-stream click actually started with. mouseDown decides
+    // it from the fingers on the trackpad, and mouseDragged/mouseUp must use
+    // the same one: a press of right followed by a release of left leaves the
+    // core holding a drag nothing will ever end.
+    private var latchedButton: pardes_mouse_button_e?
+    private var latchedCell: GridPoint?
+    // Force-click stage, reset per press. AppKit repeats stage-2 events for as
+    // long as the finger stays down, and only the transition is the gesture.
+    private var pressureStage: Int = 0
+    // Fingers currently resting on the trackpad, kept from the touch stream.
+    //
+    // mouseDown was originally trusted to carry its own touch set, and on this
+    // hardware it does not always: AppKit routes NSTouch through the four
+    // touchesXxx callbacks, and the touch set hanging off a *mouse* event can
+    // come back empty depending on how the click was produced. Empty reads as
+    // one finger, which is a two-finger Look silently degrading into a select
+    // — the exact failure this was supposed to avoid. So the count is
+    // maintained here and the mouse event's own set is preferred only when it
+    // has something in it.
+    private var restingFingers: Int = 0
 
-        // UNVERIFIED: CTFontSymbolicTraits member spelling (.traitBold/.traitItalic).
-        // A face with no italic cut returns nil here, hence the fallback to `face`.
-        func variant(_ traits: CTFontSymbolicTraits) -> CTFont {
-            CTFontCreateCopyWithSymbolicTraits(face, fontSize, nil, traits, traits) ?? face
-        }
-        regular = face
-        bold = variant(.traitBold)
-        italic = variant(.traitItalic)
-        boldItalic = variant([.traitBold, .traitItalic])
-
-        cellWidth = max(1, advance(face, 0x4D))
-        ascent = CTFontGetAscent(face)
-        cellHeight = max(1, (ascent + CTFontGetDescent(face) + CTFontGetLeading(face)).rounded(.up))
-        ruleThickness = max(1, CTFontGetUnderlineThickness(face))
-        underlineOffset = CTFontGetUnderlinePosition(face)
+    init(fontSize size: CGFloat) {
+        let built = Metrics(size: size, path: nil)
+        metrics = built
+        fontSize = size
+        fontPath = nil
 
         // 80x24 only so the window has a size to open at; the AppDelegate reads
         // gridSize back and boots the core with whatever it actually got.
-        super.init(frame: NSRect(x: 0, y: 0, width: cellWidth * 80, height: cellHeight * 24))
+        super.init(frame: NSRect(x: 0, y: 0, width: built.cellWidth * 80, height: built.cellHeight * 24))
+
+        runGlyphs.reserveCapacity(256)
+        runPositions.reserveCapacity(256)
+        // Indirect touches are the trackpad's. Without this the touch set is
+        // always empty and every click looks like one finger, which is exactly
+        // the bug that would make two-finger Look silently never fire.
+        allowedTouchTypes = [.indirect]
+        // Without a pressure configuration the deep-press stages are the
+        // system's business and stage 2 may never be delivered here.
+        // .primaryDeepClick is the one that means "a harder press is a second
+        // gesture", which is what it is being used for.
+        pressureConfiguration = NSPressureConfiguration(pressureBehavior: .primaryDeepClick)
     }
 
     required init?(coder: NSCoder) { fatalError("PardesView is built in code, not a nib") }
 
+    // MARK: - the face
+
+    /// The PostScript name of the face on screen. The only way anything
+    /// outside this file can find out which font is being drawn with — the
+    /// core has no font, so a cell-buffer snapshot cannot see one.
+    var faceName: String { CTFontCopyPostScriptName(metrics.fonts[0]) as String }
+
+    /// Put on a face, or the same face at a different size, and tell the host
+    /// the grid moved under it.
+    ///
+    /// A cell that changed size means a different number of columns fit the
+    /// same window, so this is a resize as far as the core is concerned — and
+    /// the delegate's resize path is already the one that reports both the
+    /// grid and the physical cell the PDF placement reads. Nothing here
+    /// second-guesses a file it could not load: `Metrics` falls back to the
+    /// system face, and asking for a font that is not wearable leaves the
+    /// screen exactly as it was rather than blank.
+    private func wear(size: CGFloat, path: String?) {
+        let next = Metrics(size: size, path: path)
+        // A CGGlyph is an index into a particular face. Kept across a change
+        // it would draw a different character, not a missing one.
+        glyphCache.removeAll(keepingCapacity: true)
+        metrics = next
+        fontSize = size
+        fontPath = path
+        delegate?.pardesViewDidResize(self)
+        needsDisplay = true
+    }
+
+    /// The file `Font <name>` resolved to, straight from the core.
+    func adoptFont(path: String) {
+        wear(size: fontSize, path: path)
+    }
+
+    /// Cmd+ and Cmd-. Whole points, because the cell is rounded to whole
+    /// points anyway: a tenth-of-a-point step would spend several keystrokes
+    /// landing on the same grid and look like the key had stopped working.
+    /// The range is what stays legible at the bottom and still fits a useful
+    /// number of columns at the top.
+    func zoom(by step: CGFloat) {
+        let next = min(max(fontSize + step, 6), 72)
+        guard next != fontSize else { return }
+        wear(size: next, path: fontPath)
+    }
+
+    func zoomReset() {
+        guard fontSize != defaultFontSize else { return }
+        wear(size: defaultFontSize, path: fontPath)
+    }
+
     // Row 0 at the top, so the drawing arithmetic reads like the grid it is.
     override var isFlipped: Bool { true }
     override var isOpaque: Bool { true }
     override var acceptsFirstResponder: Bool { true }
+    // A click that focuses the window should also land in the grid: this is a
+    // text surface, and having to click twice after switching apps is the kind
+    // of thing that makes an app feel foreign.
+    override func acceptsFirstMouse(for event: NSEvent?) -> Bool { true }
 
     var gridSize: (cols: UInt16, rows: UInt16) {
         let cols = min(max((bounds.width / cellWidth).rounded(.down), 1), CGFloat(UInt16.max))
@@ -176,7 +428,7 @@ final class PardesView: NSView {
         let count = pardes_frame()
         let cols = Int(pardes_frame_cols())
         let rows = Int(pardes_frame_rows())
-        fill(ctx, bounds, defaultBG, 1)
+        fill(ctx, bounds, pardesDefaultBG, 1)
         guard cols > 0, rows > 0, Int(count) == cols * rows, let cells = pardes_frame_cells() else { return }
 
         // -1 when hidden, which never matches a real cell, so hidden and "bar, so
@@ -215,20 +467,20 @@ final class PardesView: NSView {
         // line mirrored. Un-flip once for the whole glyph pass and convert each
         // baseline into it rather than fighting the text matrix per cell.
         ctx.setShouldAntialias(true)
+        // Every glyph sits at an exact multiple of cellWidth, so letting
+        // CoreText place it on a subpixel would blur a grid that is aligned by
+        // construction. Quantizing keeps the rasterizer's own cache hitting.
+        ctx.setShouldSubpixelPositionFonts(false)
+        ctx.setShouldSubpixelQuantizeFonts(true)
         ctx.saveGState()
         ctx.textMatrix = .identity
         ctx.translateBy(x: 0, y: bounds.height)
         ctx.scaleBy(x: 1, y: -1)
         let height = bounds.height
         for row in 0..<rows {
-            let base = row * cols
-            let baseline = height - (CGFloat(row) * cellHeight + ascent)
-            for col in 0..<cols {
-                let cell = cells[base + col]
-                if cell.flags & UInt8(PARDES_CELL_DEFAULT) != 0 { continue }
-                let style = resolve(cell, block: blockY == row && blockX == col)
-                drawCell(ctx, cell, style, x: CGFloat(col) * cellWidth, baseline: baseline)
-            }
+            drawRow(ctx, cells, base: row * cols, cols: cols,
+                    baseline: height - (CGFloat(row) * cellHeight + metrics.ascent),
+                    blockCol: blockY == row ? blockX : -1)
         }
         ctx.restoreGState()
 
@@ -238,73 +490,140 @@ final class PardesView: NSView {
                 // gui.zig paints U+258F here. A rect is the same picture without
                 // asking the font for a glyph it may not carry.
                 let fg = resolve(cells[y * cols + x], block: false).fg
+                ctx.setShouldAntialias(false)
                 fill(ctx, CGRect(x: CGFloat(x) * cellWidth, y: CGFloat(y) * cellHeight,
-                                 width: max(1, cellWidth / 8), height: cellHeight), fg, 1)
+                                 width: max(1, (cellWidth / 8).rounded(.up)), height: cellHeight), fg, 1)
+            }
+        }
+    }
+
+    /// One row of glyphs, batched. Consecutive cells that share a face and a
+    /// colour go to CoreText as a single call with a position array: a row of
+    /// plain text is then one draw instead of eighty, which is the difference
+    /// between a full redraw being free and being felt.
+    private func drawRow(
+        _ ctx: CGContext,
+        _ cells: UnsafePointer<pardes_cell_s>,
+        base: Int,
+        cols: Int,
+        baseline: CGFloat,
+        blockCol: Int
+    ) {
+        var runFace = Face.regular
+        var runColor: UInt32 = 0
+        var runAlpha: CGFloat = 1
+        runGlyphs.removeAll(keepingCapacity: true)
+        runPositions.removeAll(keepingCapacity: true)
+
+        func flush() {
+            guard !runGlyphs.isEmpty else { return }
+            setFill(ctx, runColor, runAlpha)
+            CTFontDrawGlyphs(metrics.fonts[runFace.rawValue], runGlyphs, runPositions, runGlyphs.count, ctx)
+            runGlyphs.removeAll(keepingCapacity: true)
+            runPositions.removeAll(keepingCapacity: true)
+        }
+
+        for col in 0..<cols {
+            let cell = cells[base + col]
+            if cell.flags & UInt8(PARDES_CELL_DEFAULT) != 0 { continue }
+            let style = resolve(cell, block: blockCol == col)
+            let x = CGFloat(col) * cellWidth
+
+            // Rules before the glyph, and independent of it: an underlined space
+            // is a real thing and so is an underlined invisible cell. They are
+            // fills, not glyphs, so they interrupt the run.
+            if cell.attrs >> UInt16(PARDES_ATTR_UL_SHIFT) != 0
+                || cell.attrs & UInt16(PARDES_ATTR_STRIKETHROUGH) != 0 {
+                flush()
+                drawRules(ctx, cell, style, x: x, baseline: baseline)
+            }
+            guard style.visible else { continue }
+
+            // UNVERIFIED: withUnsafeBytes over an imported C fixed-size array, which
+            // Swift models as an 8-tuple. String(decoding:) substitutes U+FFFD rather
+            // than trapping, and the core has shipped invalid UTF-8 through here
+            // before — the renderer must not be the thing that dies over it. prefix
+            // clamps, so a bogus len cannot walk off the eight bytes either.
+            let text = withUnsafeBytes(of: cell.text) { raw in
+                String(decoding: raw.prefix(Int(cell.len)), as: UTF8.self)
+            }
+            guard !text.isEmpty, text != " " else { continue }
+
+            let face = Face(bold: cell.attrs & UInt16(PARDES_ATTR_BOLD) != 0,
+                            italic: cell.attrs & UInt16(PARDES_ATTR_ITALIC) != 0)
+            let units = text.utf16
+            let known = units.count == 1 ? glyph(face, units.first!) : 0
+            if known != 0 {
+                if !runGlyphs.isEmpty
+                    && (face != runFace || style.fg != runColor || style.alpha != runAlpha) {
+                    flush()
+                }
+                runFace = face
+                runColor = style.fg
+                runAlpha = style.alpha
+                runGlyphs.append(known)
+                runPositions.append(CGPoint(x: x, y: baseline))
+                continue
             }
+
+            // Emoji, combining marks and anything the face is missing: CTLine finds
+            // a fallback font. The position is set explicitly per cell — this is a
+            // fixed grid, and letting CoreText advance across a row would drift off
+            // it.
+            flush()
+            setFill(ctx, style.fg, style.alpha)
+            let attributed = NSAttributedString(string: text, attributes: [fontAttribute: metrics.fonts[face.rawValue]])
+            ctx.textPosition = CGPoint(x: x, y: baseline)
+            CTLineDraw(CTLineCreateWithAttributedString(attributed as CFAttributedString), ctx)
+            // CTLineDraw leaves the text position at the END of what it drew,
+            // and textPosition IS the translation of the text matrix, which
+            // CTFontDrawGlyphs then applies to every position it is handed. So
+            // one fallback glyph silently displaces the entire rest of the
+            // frame by that glyph's advance, down and to the right — and since
+            // the wrap marker and the em dash take this path, that is most
+            // files. Put it back before anything else draws.
+            ctx.textMatrix = .identity
         }
+        flush()
+    }
+
+    /// 0 is .notdef, i.e. "this face does not have it" — a real answer, cached
+    /// like any other, because the CTLine fallback it sends the caller to costs
+    /// far more than the lookup it would otherwise repeat every frame.
+    private func glyph(_ face: Face, _ character: UniChar) -> CGGlyph {
+        if character < 128 { return metrics.asciiGlyphs[face.rawValue][Int(character)] }
+        let key = UInt32(face.rawValue) << 16 | UInt32(character)
+        if let cached = glyphCache[key] { return cached }
+        var input = character
+        var found = CGGlyph(0)
+        _ = CTFontGetGlyphsForCharacters(metrics.fonts[face.rawValue], &input, &found, 1)
+        glyphCache[key] = found
+        return found
     }
 
-    private func drawCell(
+    private func drawRules(
         _ ctx: CGContext,
         _ cell: pardes_cell_s,
         _ style: (fg: UInt32, bg: UInt32, alpha: CGFloat, visible: Bool),
         x: CGFloat,
         baseline: CGFloat
     ) {
-        // Rules before the glyph, and independent of it: an underlined space is a
-        // real thing and so is an underlined invisible cell.
         let underline = Int(cell.attrs >> PARDES_ATTR_UL_SHIFT) & 7
         if underline != Int(PARDES_UL_OFF) {
-            let y = baseline + underlineOffset
-            fill(ctx, CGRect(x: x, y: y, width: cellWidth, height: ruleThickness), style.fg, style.alpha)
+            let y = baseline + metrics.underlineOffset
+            fill(ctx, CGRect(x: x, y: y, width: cellWidth, height: metrics.ruleThickness), style.fg, style.alpha)
             // ponytail: curly, dotted and dashed all come out solid; only double
             // earns its second rule. ctx.setLineDash for two of them and a sine
             // path for the third is the upgrade, once anyone notices.
             if underline == Int(PARDES_UL_DOUBLE) {
-                fill(ctx, CGRect(x: x, y: y - ruleThickness * 2, width: cellWidth, height: ruleThickness),
+                fill(ctx, CGRect(x: x, y: y - metrics.ruleThickness * 2, width: cellWidth, height: metrics.ruleThickness),
                      style.fg, style.alpha)
             }
         }
         if cell.attrs & UInt16(PARDES_ATTR_STRIKETHROUGH) != 0 {
-            fill(ctx, CGRect(x: x, y: baseline + ascent * 0.3, width: cellWidth, height: ruleThickness),
+            fill(ctx, CGRect(x: x, y: baseline + metrics.ascent * 0.3, width: cellWidth, height: metrics.ruleThickness),
                  style.fg, style.alpha)
         }
-        guard style.visible else { return }
-
-        // UNVERIFIED: withUnsafeBytes over an imported C fixed-size array, which
-        // Swift models as an 8-tuple. String(decoding:) substitutes U+FFFD rather
-        // than trapping, and the core has shipped invalid UTF-8 through here
-        // before — the renderer must not be the thing that dies over it. prefix
-        // clamps, so a bogus len cannot walk off the eight bytes either.
-        let text = withUnsafeBytes(of: cell.text) { raw in
-            String(decoding: raw.prefix(Int(cell.len)), as: UTF8.self)
-        }
-        guard !text.isEmpty, text != " " else { return }
-
-        let heavy = cell.attrs & UInt16(PARDES_ATTR_BOLD) != 0
-        let slanted = cell.attrs & UInt16(PARDES_ATTR_ITALIC) != 0
-        let font = heavy ? (slanted ? boldItalic : bold) : (slanted ? italic : regular)
-        setFill(ctx, style.fg, style.alpha)
-
-        // ponytail: no glyph cache — a cmap lookup per cell, and a whole CTLine
-        // for anything that is not one BMP scalar the face covers. A
-        // [UnicodeScalar: CGGlyph] map, then an atlas, is the upgrade path when a
-        // full redraw shows up in Instruments.
-        let units = text.utf16
-        if units.count == 1, var character = units.first {
-            var glyph = CGGlyph(0)
-            if CTFontGetGlyphsForCharacters(font, &character, &glyph, 1) {
-                var position = CGPoint(x: x, y: baseline)
-                CTFontDrawGlyphs(font, &glyph, &position, 1, ctx)
-                return
-            }
-        }
-        // Emoji, combining marks and anything the face is missing: CTLine finds a
-        // fallback font. The position is set explicitly per cell — this is a fixed
-        // grid, and letting CoreText advance across a row would drift off it.
-        let attributed = NSAttributedString(string: text, attributes: [fontAttribute: font])
-        ctx.textPosition = CGPoint(x: x, y: baseline)
-        CTLineDraw(CTLineCreateWithAttributedString(attributed as CFAttributedString), ctx)
     }
 
     private func setFill(_ ctx: CGContext, _ rgb: UInt32, _ alpha: CGFloat) {
@@ -319,12 +638,78 @@ final class PardesView: NSView {
         ctx.fill(rect)
     }
 
+    // MARK: - the core, and the pump
+
+    /// Everything below ends here. Posting the notification in one place is
+    /// what guarantees no entry point can feed the core and forget to ask for
+    /// the tick that performs it.
+    private func fed() {
+        NotificationCenter.default.post(name: pardesDidInputNotification, object: self)
+    }
+
+    func typeKey(_ cp: UInt32, text: String, mods: UInt32) {
+        // The pointer is borrowed for the call and nowhere else, which is the only
+        // thing the header promises about it.
+        text.withCString { pardes_key(cp, $0, text.utf8.count, mods) }
+        fed()
+    }
+
+    // `mods` defaults to none because a synthesized gesture carries no
+    // keyboard state; the NSEvent overrides always pass the real mask. Ctrl is
+    // the one the core actually consults — a left press with it held is
+    // goto-definition — so dropping it here would silently delete a feature.
+    func press(_ button: pardes_mouse_button_e, at cell: GridPoint, mods: UInt32 = 0) {
+        pardes_mouse(button, PARDES_MOUSE_PRESS, cell.col, cell.row, mods)
+        fed()
+    }
+
+    func release(_ button: pardes_mouse_button_e, at cell: GridPoint, mods: UInt32 = 0) {
+        pardes_mouse(button, PARDES_MOUSE_RELEASE, cell.col, cell.row, mods)
+        fed()
+    }
+
+    func drag(_ button: pardes_mouse_button_e, to cell: GridPoint, mods: UInt32 = 0) {
+        pardes_mouse(button, PARDES_MOUSE_DRAG, cell.col, cell.row, mods)
+        fed()
+    }
+
+    func motion(to cell: GridPoint, mods: UInt32 = 0) {
+        pardes_mouse(PARDES_MOUSE_NONE, PARDES_MOUSE_MOTION, cell.col, cell.row, mods)
+        fed()
+    }
+
+    /// A press and its release with nothing in between, which is what every
+    /// synthesized click is: a trackpad gesture we recognised rather than a
+    /// button the user held.
+    func click(_ button: pardes_mouse_button_e, at cell: GridPoint, mods: UInt32 = 0) {
+        press(button, at: cell, mods: mods)
+        release(button, at: cell, mods: mods)
+    }
+
+    /// One discrete wheel notch, as opposed to the continuous travel below.
+    func wheel(_ button: pardes_mouse_button_e, at cell: GridPoint, mods: UInt32 = 0) {
+        pardes_mouse(button, PARDES_MOUSE_PRESS, cell.col, cell.row, mods)
+        fed()
+    }
+
+    func scroll(rows: CGFloat, cols: CGFloat = 0, at cell: GridPoint) {
+        guard rows != 0 || cols != 0 else { return }
+        pardes_scroll(Float(rows), Float(cols), cell.col, cell.row)
+        fed()
+    }
+
+    func rotate(degrees: CGFloat) {
+        guard degrees != 0 else { return }
+        pardes_rotate(Float(degrees))
+        fed()
+    }
+
     // MARK: - keyboard
 
     override func keyDown(with event: NSEvent) {
         let flags = event.modifierFlags
         // The ABI has no super bit, so a Command chord cannot be expressed at all.
-        // Cmd-V is the paste the delegate owns; every other one is swallowed
+        // Anything the main menu claims never reaches here; the rest is swallowed
         // rather than delivered as the bare keystroke the core would insert.
         if flags.contains(.command) {
             if event.charactersIgnoringModifiers?.lowercased() == "v" {
@@ -376,52 +761,179 @@ final class PardesView: NSView {
         // carry text.
         let functional = codepoint < 0x20 || codepoint == 0x7F || codepoint >= 0xF0000
         let text = functional || control || option ? "" : composed
-        // The pointer is borrowed for the call and nowhere else, which is the only
-        // thing the header promises about it.
-        text.withCString { pardes_key(codepoint, $0, text.utf8.count, modifiers(flags)) }
-        NotificationCenter.default.post(name: inputNotification, object: self)
+        // Typing is the moment the pointer stops being interesting and starts
+        // sitting on top of the words. It comes back on the next mouse move.
+        NSCursor.setHiddenUntilMouseMoves(true)
+        typeKey(codepoint, text: text, mods: modifiers(flags))
+    }
+
+    // MARK: - trackpad
+
+    // NSTouch arrives through these four and nowhere else. They are the only
+    // reliable source of "how many fingers are down right now": the touch set
+    // on a mouse event is an accident of how the click was produced, and an
+    // empty one is indistinguishable from one finger.
+    override func touchesBegan(with event: NSEvent) { countTouches(event) }
+    override func touchesMoved(with event: NSEvent) { countTouches(event) }
+    override func touchesEnded(with event: NSEvent) { countTouches(event) }
+    override func touchesCancelled(with event: NSEvent) { countTouches(event) }
+
+    private func countTouches(_ event: NSEvent) {
+        restingFingers = event.touches(matching: .touching, in: nil).count
+        trace("touch: resting=\(restingFingers)")
     }
 
     // MARK: - mouse
 
-    override func mouseDown(with event: NSEvent) { send(PARDES_MOUSE_LEFT, PARDES_MOUSE_PRESS, event) }
-    override func mouseUp(with event: NSEvent) { send(PARDES_MOUSE_LEFT, PARDES_MOUSE_RELEASE, event) }
-    override func mouseDragged(with event: NSEvent) { send(PARDES_MOUSE_LEFT, PARDES_MOUSE_DRAG, event) }
-    override func rightMouseDown(with event: NSEvent) { send(PARDES_MOUSE_RIGHT, PARDES_MOUSE_PRESS, event) }
-    override func rightMouseUp(with event: NSEvent) { send(PARDES_MOUSE_RIGHT, PARDES_MOUSE_RELEASE, event) }
-    override func rightMouseDragged(with event: NSEvent) { send(PARDES_MOUSE_RIGHT, PARDES_MOUSE_DRAG, event) }
+    // All three button streams land in the same three functions, because which
+    // stream a trackpad click arrives on is not something the app gets to know
+    // in advance: with macOS's secondary click on, two AND three fingers both
+    // come in as rightMouseDown. The button is therefore decided once, at the
+    // press, from the fingers plus the stream, and then LATCHED — the core is
+    // tracking a drag keyed by button, and answering a press of 3 with a
+    // release of 1 leaves it holding a sweep nothing will ever end.
+    //
+    // The count itself is maintained by the touchesXxx callbacks above; see
+    // beginClick for why it can only come from there.
+    private func beginClick(_ stream: pardes_mouse_button_e, _ event: NSEvent) {
+        guard let at = cell(for: event) else { return }
+        pressureStage = 0
+        // The count comes from the touch stream and NEVER from the mouse event.
+        // Asking a mouse event for its touches is not merely unreliable, it
+        // raises: -[NSEvent touchesMatchingPhase:inView:] is defined for
+        // gesture and touch events, and on anything else AppKit throws, catches
+        // it inside its own event dispatch, and abandons the rest of this
+        // method. Nothing crashes and nothing is logged — every click just
+        // silently stops working, a plain drag included, while rotation and
+        // scrolling carry on as if the backend were fine. That is exactly how
+        // this presented, and it is why restingFingers exists.
+        let button = Trackpad.button(stream: stream, fingers: restingFingers)
+        trace("press: stream=\(stream.rawValue) fingers=\(restingFingers) -> button=\(button.rawValue)")
+        latchedButton = button
+        latchedCell = at
+        press(button, at: at, mods: modifiers(event.modifierFlags))
+    }
+
+    private func continueClick(_ event: NSEvent) {
+        guard let button = latchedButton, let at = cell(for: event) else { return }
+        latchedCell = at
+        drag(button, to: at, mods: modifiers(event.modifierFlags))
+    }
+
+    private func endClick(_ event: NSEvent) {
+        pressureStage = 0
+        // Already nil when the force click below converted this press: it
+        // released the button itself and there is nothing left to end.
+        guard let button = latchedButton else { return }
+        latchedButton = nil
+        guard let at = cell(for: event) else { return }
+        latchedCell = at
+        release(button, at: at, mods: modifiers(event.modifierFlags))
+    }
+
+    override func mouseDown(with event: NSEvent) { beginClick(PARDES_MOUSE_LEFT, event) }
+    override func mouseDragged(with event: NSEvent) { continueClick(event) }
+    override func mouseUp(with event: NSEvent) { endClick(event) }
+    // Where a two-finger click lands with macOS's own secondary click on, and
+    // where a three-finger one lands too — hence the finger count in
+    // Trackpad.button rather than a hardcoded RIGHT here.
+    override func rightMouseDown(with event: NSEvent) { beginClick(PARDES_MOUSE_RIGHT, event) }
+    override func rightMouseDragged(with event: NSEvent) { continueClick(event) }
+    override func rightMouseUp(with event: NSEvent) { endClick(event) }
     // otherMouse covers button 2 and up. acme's vocabulary stops at three, so
     // every one of them lands on middle rather than being invented into a fourth.
-    override func otherMouseDown(with event: NSEvent) { send(PARDES_MOUSE_MIDDLE, PARDES_MOUSE_PRESS, event) }
-    override func otherMouseUp(with event: NSEvent) { send(PARDES_MOUSE_MIDDLE, PARDES_MOUSE_RELEASE, event) }
-    override func otherMouseDragged(with event: NSEvent) { send(PARDES_MOUSE_MIDDLE, PARDES_MOUSE_DRAG, event) }
-    override func mouseMoved(with event: NSEvent) { send(PARDES_MOUSE_NONE, PARDES_MOUSE_MOTION, event) }
+    override func otherMouseDown(with event: NSEvent) { beginClick(PARDES_MOUSE_MIDDLE, event) }
+    override func otherMouseDragged(with event: NSEvent) { continueClick(event) }
+    override func otherMouseUp(with event: NSEvent) { endClick(event) }
+
+    /// A deep press, which is a second gesture layered on the click already in
+    /// flight. AppKit keeps sending stage-2 events while the finger stays down,
+    /// so only the transition counts.
+    ///
+    /// Whatever button is in flight is released before the middle one goes out:
+    /// a middle press arriving while the core holds a left select-drag is
+    /// acme's 1-2 chord, which is Cut. Releasing first costs a cursor move at
+    /// the click point — which is what clicking there would have done anyway.
+    ///
+    /// Not gated on the press being a LEFT one, which is what stopped this
+    /// working: on a Force Touch trackpad the deep press is just as likely to
+    /// have arrived on the right stream, and an in-flight Look upgraded by
+    /// pressing harder is precisely the gesture. Already-Exec is the only case
+    /// with nothing to do.
+    override func pressureChange(with event: NSEvent) {
+        trace("pressure: stage=\(event.stage) latched=\(String(describing: latchedButton?.rawValue))")
+        guard pressureStage < 2 else { return }
+        pressureStage = event.stage
+        guard event.stage == 2 else { return }
+        guard let at = latchedCell, let current = latchedButton,
+              current != Trackpad.forceClickButton else { return }
+        latchedButton = nil
+        release(current, at: at, mods: modifiers(event.modifierFlags))
+        click(Trackpad.forceClickButton, at: at, mods: modifiers(event.modifierFlags))
+    }
+
+    override func mouseMoved(with event: NSEvent) {
+        guard let at = cell(for: event) else { return }
+        motion(to: at, mods: modifiers(event.modifierFlags))
+    }
 
     override func scrollWheel(with event: NSEvent) {
         guard let at = cell(for: event) else { return }
         if event.hasPreciseScrollingDeltas {
-            // The core scrolls a row at a time, so libpardes accumulates the
-            // sub-row travel and spends it as wheel presses — which is why the
+            // The core scrolls a cell at a time, so libpardes accumulates the
+            // sub-cell travel and spends it as wheel presses — which is why the
             // cell has to travel with the delta.
-            pardes_scroll(Float(-event.scrollingDeltaY / cellHeight), at.col, at.row)
-        } else if event.scrollingDeltaY != 0 {
+            scroll(rows: -event.scrollingDeltaY / cellHeight,
+                   cols: -event.scrollingDeltaX / cellWidth,
+                   at: at)
+        } else {
             // AppKit's sign is the opposite of the DOM's: positive deltaY means the
             // content moved down, which is a scroll back through history.
-            let button = event.scrollingDeltaY > 0 ? PARDES_MOUSE_WHEEL_UP : PARDES_MOUSE_WHEEL_DOWN
-            pardes_mouse(button, PARDES_MOUSE_PRESS, at.col, at.row, modifiers(event.modifierFlags))
-        } else {
-            return
+            if event.scrollingDeltaY != 0 {
+                wheel(event.scrollingDeltaY > 0 ? PARDES_MOUSE_WHEEL_UP : PARDES_MOUSE_WHEEL_DOWN,
+                      at: at, mods: modifiers(event.modifierFlags))
+            }
+            if event.scrollingDeltaX != 0 {
+                wheel(event.scrollingDeltaX > 0 ? PARDES_MOUSE_WHEEL_LEFT : PARDES_MOUSE_WHEEL_RIGHT,
+                      at: at, mods: modifiers(event.modifierFlags))
+            }
         }
-        NotificationCenter.default.post(name: inputNotification, object: self)
     }
 
-    private func send(_ button: pardes_mouse_button_e, _ kind: pardes_mouse_kind_e, _ event: NSEvent) {
-        guard let at = cell(for: event) else { return }
-        pardes_mouse(button, kind, at.col, at.row, modifiers(event.modifierFlags))
-        NotificationCenter.default.post(name: inputNotification, object: self)
+    /// Two fingers twisted on the trackpad are the search-step keys: clockwise
+    /// walks forward through the matches, counterclockwise back. It is a dial,
+    /// and n/N is what a dial over a list of hits means. libpardes owns the
+    /// quantizing, exactly as it does for scroll.
+    override func rotate(with event: NSEvent) {
+        trace("rotate: degrees=\(event.rotation) phase=\(event.phase.rawValue)")
+        // A gesture starting drops whatever the last one left banked, so the
+        // first degree of a new twist cannot inherit a nearly-complete notch.
+        if event.phase == .began { pardes_rotate(0) }
+        rotate(degrees: CGFloat(event.rotation))
     }
 
-    private func cell(for event: NSEvent) -> (col: UInt16, row: UInt16)? {
+    /// What the trackpad actually delivered, under PARDES_LOG — the same
+    /// variable the Zig side gates its logger on (src/macos.zig).
+    ///
+    /// This is not scaffolding left behind. Which events a trackpad produces is
+    /// decided by the hardware and by four different System Settings switches
+    /// (secondary click, three-finger drag, force click, "look up"), none of
+    /// which this process can read, and every one of which turns a gesture into
+    /// a different NSEvent or into none at all. When someone reports that
+    /// two-finger Look does nothing, this is the only thing that can answer
+    /// whether AppKit saw two fingers, one, or no click at all.
+    private func trace(_ message: @autoclosure () -> String) {
+        guard PardesView.tracing else { return }
+        FileHandle.standardError.write(Data(("pardes: " + message() + "\n").utf8))
+    }
+
+    private static let tracing = ProcessInfo.processInfo.environment["PARDES_LOG"] != nil
+
+    private func cell(for event: NSEvent) -> GridPoint? {
+        cellAt(convert(event.locationInWindow, from: nil))
+    }
+
+    func cellAt(_ point: CGPoint) -> GridPoint? {
         // Clamp against the frame the core last rendered, not against our own
         // metrics: a window that has been resized but not yet ticked would
         // otherwise report a column the core has no cell for. Before the first
@@ -429,10 +941,9 @@ final class PardesView: NSView {
         let cols = Int(pardes_frame_cols())
         let rows = Int(pardes_frame_rows())
         guard cols > 0, rows > 0 else { return nil }
-        let point = convert(event.locationInWindow, from: nil)
         let col = min(max(Int(point.x / cellWidth), 0), cols - 1)
         let row = min(max(Int(point.y / cellHeight), 0), rows - 1)
-        return (UInt16(col), UInt16(row))
+        return GridPoint(col: UInt16(col), row: UInt16(row))
     }
 
     // MARK: - geometry
@@ -448,6 +959,12 @@ final class PardesView: NSView {
                                        userInfo: nil))
     }
 
+    override func resetCursorRects() {
+        // Every cell in this view is text, including the tags. An arrow over a
+        // grid you can sweep and click words in is the wrong affordance.
+        addCursorRect(bounds, cursor: .iBeam)
+    }
+
     override func setFrameSize(_ newSize: NSSize) {
         super.setFrameSize(newSize)
         // AppKit resizes a view many times over one drag and almost all of those
@@ -475,4 +992,5 @@ final class PardesView: NSView {
 // ponytail: no NSTextInputClient, so dead keys and IME composition never reach
 // the core — keyDown reads `characters` and that is the whole story. Adopting
 // the protocol and routing through interpretKeyEvents is the upgrade when
-// someone needs to type Japanese.
+// someone needs to type Japanese, and it needs the core to be able to render an
+// underlined preedit run first.