merge the macOS app branch: the AppKit shell, pixel attachments, live theming, and mupdf -Djpx

Three commits off 38e9919 (macos-app@upstream) merged into main's ghostty bump.
No textual conflicts, and two things the merge needed:

- nested.zig asked libc for fstatat. Darwin has it; on linux std.c declares it
  `void` (glibc hides it behind a versioned symbol std cannot name), so the tty
  build stopped at 'type void not a function'. statNoFollow keeps fstatat on
  darwin and asks statx on linux for the same three fields, which is what this
  file did before the branch generalized it to both platforms.

- .DS_Store rode along with a797a1a. Deleted, and .gitignore now says so.

linux: snap 86/86, unit-test, image-harness and mupdf-check green. nested.zig
also type-checks for aarch64-macos.

17 files changed, 3336 insertions, 401 deletions

diff --git a/src/builtins.zig b/src/builtins.zig
index 3ccbdeed..f207ed9f 100644
--- a/src/builtins.zig
+++ b/src/builtins.zig
@@ -35,7 +35,7 @@ const config = @import("config.zig");
 /// GUI-only file behind a comptime branch, the way look.zig imports the web's
 /// source archive: the tty and web builds evaluate the other arm and compile
 /// none of it.
-const fonts = if (pardes.platform == .gui) @import("gui/fonts.zig") else struct {};
+const fonts = if (pardes.font_picker) @import("fonts.zig") else struct {};
 
 /// What a builtin gets to act on. One bundle rather than five parameters
 /// because most builtins want two of them and zig rejects the unused rest.
@@ -343,7 +343,7 @@ pub const Crt = struct {
 /// its next pass and re-rasters. Exactly the shape Restore already has.
 pub const Font = struct {
     pub const takes_arg = true;
-    pub const enabled = pardes.platform == .gui;
+    pub const enabled = pardes.font_picker;
     pub fn run(c: Ctx) void {
         if (comptime enabled) apply(c) else unreachable;
     }
@@ -369,7 +369,7 @@ pub const Font = struct {
 /// them would mean the list wearing one on the way past. See fonts.monospaced.
 pub const FontSel = struct {
     pub const output: OutputTraits = .{ .name = config.fonts_buffer, .steps = true, .executes = true };
-    pub const enabled = pardes.platform == .gui;
+    pub const enabled = pardes.font_picker;
     pub fn run(c: Ctx) void {
         if (comptime enabled) apply(c) else unreachable;
     }
@@ -460,7 +460,13 @@ pub const Ascii = struct {
 pub const Save = struct {
     pub fn run(c: Ctx) void {
         // an output buffer has no file behind it — nothing to write
-        if (c.pane.file) |f| if (output_pane.fileTraits(f.output).saves) c.p.emit(.{ .save_file = .{ .pane = @intCast(c.id) } });
+        if (c.pane.file) |*f| {
+            if (!output_pane.fileTraits(f.output).saves) return;
+            c.p.emit(.{ .save_file = .{ .pane = @intCast(c.id) } });
+            // ...and this edit is now the one on disk. See File.saved_revision
+            // for why the mark goes here rather than after the write.
+            f.saved_revision = f.revision;
+        }
     }
 };
 
@@ -536,6 +542,22 @@ pub const Help = struct {
     }
 };
 
+/// Where pardes read its startup commands from — the path, printed into an
+/// output buffer, `SPC f c` or the word executed anywhere.
+///
+/// The one question docs/config.md cannot answer, because the answer depends
+/// on the machine: XDG_CONFIG_HOME if it is set and absolute, else
+/// ~/Library/Application Support/pardes on macOS and ~/.config/pardes
+/// everywhere else. Printing it beats documenting it — the row is ordinary
+/// text, so a right click on it opens the file, and when there is no file
+/// there yet the path is still exactly what you needed to know.
+pub const Config = struct {
+    pub const output: OutputTraits = .{ .name = config.config_buffer };
+    pub fn run(c: Ctx) void {
+        output_pane.openConfig(c.p, c.id) catch |err| c.p.reportError(c.id, "config", err);
+    }
+};
+
 // ---- search ----
 
 // The two builtins that ASK for something — Find walks file NAMES under this
diff --git a/src/config.zig b/src/config.zig
index 67314fd9..189d6a0e 100644
--- a/src/config.zig
+++ b/src/config.zig
@@ -115,6 +115,9 @@ pub const leader_path = paths: {
         .New = "fn",
         .Find = "ff",
         .Grep = "fg",
+        // the config FILE joins the file group: `SPC f c` says where pardes
+        // read (or would read) its startup commands from.
+        .Config = "fc",
         .Tutor = "ht",
         .Newcol = "cn",
         .Delcol = "cd",
@@ -163,7 +166,7 @@ pub const leader_path = paths: {
     // web they are not builtins at all (see builtins.zig) and the literal's
     // type has no field to write. `Font` takes a NAME, so it has no path, for
     // the same reason `Theme` has none.
-    if (pardes.platform == .gui) {
+    if (pardes.font_picker) {
         table.set(.FontSel, "tf");
         table.set(.Font, null);
     }
@@ -623,6 +626,7 @@ pub const pipe_marker = " |";
 /// these changes only what you read in a tag.
 pub const search_buffer = "+Search";
 pub const help_buffer = "+Help";
+pub const config_buffer = "+Config";
 pub const jumps_buffer = "+Jumps";
 pub const themes_buffer = "+Themes";
 pub const fonts_buffer = "+Fonts";
diff --git a/src/gui/fonts.zig b/src/fonts.zig
index 54210136..28789e3d 100644
--- a/src/gui/fonts.zig
+++ b/src/fonts.zig
@@ -1,29 +1,43 @@
 //! The fonts installed on the machine: the list the picker shows, the path a
 //! `Font <name>` resolves to, and the one word the two sides of that say to
 //! each other. builtins.zig reads this file to build the rows and to resolve a
-//! name; gui.zig reads it to learn which file to load. It is the whole seam,
-//! because the core has no font and the shell has no builtin dispatch.
+//! name; gui.zig and macos.zig read it to learn which file to load. It is the
+//! whole seam, because the core has no font and the shell has no builtin
+//! dispatch.
 //!
-//! It lives under gui/ rather than at src/ — where the core lies flat —
-//! because it only exists in a GUI build: builtins.zig imports it behind
-//! `platform == .gui`, so the tty binary compiles not one line of this and
-//! never opens a font directory, and the browser (which has no font
-//! directories to open) is out for a better reason than taste.
+//! It lives at src/ rather than under gui/ because two shells now draw their
+//! own text: builtins.zig imports it behind `platform == .gui or .macos`, so
+//! the tty binary compiles not one line of this and never opens a font
+//! directory, and the browser (which has no font directories to open) is out
+//! for a better reason than taste.
 //!
-//! No fontconfig. Enumerating fonts on a Unix box is a walk over four
-//! well-known directories, and the one thing the picker must know about each
-//! face — whether every glyph has the same advance — is four small sfnt reads.
-//! That avoids initializing a FreeType face for every file in the directory.
+//! No fontconfig and no CoreText. Enumerating fonts is a walk over a handful
+//! of well-known directories, and the one thing the picker must know about
+//! each face — whether every glyph has the same advance — is four small sfnt
+//! reads. That avoids initializing a FreeType face for every file in the
+//! directory, and it keeps the answer identical on both platforms: the shells
+//! disagree about how to RASTERIZE a file, never about which files there are.
 const std = @import("std");
+const builtin = @import("builtin");
 const libc = std.c;
 
-/// Where a unix box keeps fonts. The last two are relative to $HOME (a machine
-/// with no $HOME simply has neither). ponytail: this is the freedesktop list
-/// minus /usr/share/X11/fonts, whose legacy bitmap formats are outside this
-/// TTF/OTF picker; XDG_DATA_DIRS is the general answer if another font root
-/// becomes common.
-const system_dirs = [_][]const u8{ "/usr/share/fonts", "/usr/local/share/fonts" };
-const home_dirs = [_][]const u8{ ".local/share/fonts", ".fonts" };
+/// Where each platform keeps fonts. The `home` list is relative to $HOME (a
+/// machine with no $HOME simply has neither). ponytail: the unix set is the
+/// freedesktop list minus /usr/share/X11/fonts, whose legacy bitmap formats
+/// are outside this TTF/OTF picker; XDG_DATA_DIRS is the general answer if
+/// another font root becomes common.
+///
+/// macOS keeps a third of its faces — Menlo and Courier among them — inside
+/// `Supplemental`, which is an ordinary directory the walk would reach anyway;
+/// it is named because the depth cap is the only thing that would stop it.
+const system_dirs = switch (builtin.os.tag) {
+    .macos => [_][]const u8{ "/System/Library/Fonts", "/System/Library/Fonts/Supplemental", "/Library/Fonts" },
+    else => [_][]const u8{ "/usr/share/fonts", "/usr/local/share/fonts" },
+};
+const home_dirs = switch (builtin.os.tag) {
+    .macos => [_][]const u8{"Library/Fonts"},
+    else => [_][]const u8{ ".local/share/fonts", ".fonts" },
+};
 
 /// The same three safety rails look.find has, for the same reason: this walk
 /// runs INSIDE the keystroke that asked for it, so it must end whatever it is
@@ -113,7 +127,13 @@ fn scan(arena: std.mem.Allocator, wanted: ?[]const []const u8) []const Font {
                 continue;
             }
             const ext = std.fs.path.extension(e.basename);
-            if (!std.ascii.eqlIgnoreCase(ext, ".ttf") and !std.ascii.eqlIgnoreCase(ext, ".otf")) continue;
+            // .ttc is a collection: several cuts of one family in a single
+            // file, which is how macOS ships Menlo, Courier and a third of
+            // everything else. The probe below reads face 0 out of one, and
+            // the shell loading it takes the same face — see tableOffset.
+            if (!std.ascii.eqlIgnoreCase(ext, ".ttf") and
+                !std.ascii.eqlIgnoreCase(ext, ".otf") and
+                !std.ascii.eqlIgnoreCase(ext, ".ttc")) continue;
             const name = e.basename[0 .. e.basename.len - ext.len];
             if (wanted) |names| {
                 var matches = false;
@@ -239,21 +259,59 @@ fn monospaced(path_z: [*:0]const u8) bool {
 /// Where `tag`'s table starts, read out of an sfnt table directory. Called
 /// twice per font, which is the only reason it is not inline up there.
 fn tableOffset(head: []const u8, tag: *const [4]u8) ?u32 {
-    if (head.len < 12) return null;
+    const dir = head[sfntBase(head) orelse return null ..];
+    if (dir.len < 12) return null;
     // 0x00010000 TrueType outlines, "OTTO" CFF ones, "true" the old Apple
-    // spelling. Anything else — a .ttc collection, a WOFF, a lie about its
-    // extension — is not an sfnt face this picker can inspect.
-    const ver = std.mem.readInt(u32, head[0..4], .big);
+    // spelling. Anything else — a WOFF, a lie about its extension — is not an
+    // sfnt face this picker can inspect.
+    const ver = std.mem.readInt(u32, dir[0..4], .big);
     if (ver != 0x00010000 and ver != 0x4F54544F and ver != 0x74727565) return null;
-    const num = std.mem.readInt(u16, head[4..6], .big);
+    const num = std.mem.readInt(u16, dir[4..6], .big);
     var i: usize = 0;
-    while (i < num and 12 + (i + 1) * 16 <= head.len) : (i += 1) {
-        const rec = head[12 + i * 16 ..][0..16];
+    while (i < num and 12 + (i + 1) * 16 <= dir.len) : (i += 1) {
+        const rec = dir[12 + i * 16 ..][0..16];
+        // Table offsets in a collection are from the start of the FILE, not
+        // from the directory that named them, so this needs no adjusting.
         if (std.mem.eql(u8, rec[0..4], tag)) return std.mem.readInt(u32, rec[8..12], .big);
     }
     return null;
 }
 
+/// Where the sfnt table directory begins. Zero for an ordinary font file; for
+/// a `ttcf` collection, the offset of face 0 — the cut the file is named
+/// after, and the one a shell asked for this path will load. A collection
+/// whose first face lies past what was read has no answer here rather than a
+/// guessed one.
+fn sfntBase(head: []const u8) ?usize {
+    if (head.len < 12) return null;
+    if (!std.mem.eql(u8, head[0..4], "ttcf")) return 0;
+    if (head.len < 16) return null;
+    if (std.mem.readInt(u32, head[8..12], .big) == 0) return null; // numFonts
+    const base = std.mem.readInt(u32, head[12..16], .big);
+    return if (base + 12 <= head.len) base else null;
+}
+
+/// A scratch font path only this process writes.
+///
+/// Not a fixed name: `zig build unit-test` compiles this module into two test
+/// binaries and runs them CONCURRENTLY, so a shared path in /tmp is one test
+/// truncating the file another is halfway through reading. That surfaced as
+/// `monospaced` flatly disagreeing with the bytes it had just been handed,
+/// about one run in three, which reads like a bug in the probe and is not one.
+fn scratchFont(buf: *[64:0]u8, ext: []const u8) [:0]const u8 {
+    return std.fmt.bufPrintSentinel(buf, "/tmp/pardes-fonts-test-{d}{s}", .{
+        @as(u32, @intCast(libc.getpid())), ext,
+    }, 0) catch unreachable;
+}
+
+/// Write `bytes` where `monospaced` can read them back.
+fn writeScratch(path: [:0]const u8, bytes: []const u8) !void {
+    const fd = libc.open(path, .{ .ACCMODE = .WRONLY, .CREAT = true, .TRUNC = true }, @as(c_uint, 0o600));
+    try std.testing.expect(fd >= 0);
+    defer _ = libc.close(fd);
+    try std.testing.expectEqual(@as(isize, @intCast(bytes.len)), libc.write(fd, bytes.ptr, bytes.len));
+}
+
 test "monospaced reads the advances out of a real sfnt layout" {
     // A whole font in 92 bytes: the header, a two-record table directory, and
     // an hhea + hmtx that between them say "three glyphs, all 600 units wide".
@@ -269,23 +327,79 @@ test "monospaced reads the advances out of a real sfnt layout" {
     std.mem.writeInt(u16, f[44 + 34 ..][0..2], 3, .big); // numberOfHMetrics
     for (0..3) |i| std.mem.writeInt(u16, f[80 + i * 4 ..][0..2], 600, .big);
 
-    const path = "/tmp/pardes-fonts-test.ttf";
-    {
-        const fd = libc.open(path, .{ .ACCMODE = .WRONLY, .CREAT = true, .TRUNC = true }, @as(c_uint, 0o644));
-        try std.testing.expect(fd >= 0);
-        defer _ = libc.close(fd);
-        try std.testing.expectEqual(@as(isize, f.len), libc.write(fd, &f, f.len));
-    }
+    var path_buf: [64:0]u8 = undefined;
+    const path = scratchFont(&path_buf, ".ttf");
+    defer _ = libc.unlink(path);
+    try writeScratch(path, &f);
     try std.testing.expect(monospaced(path));
 
     // ...and one glyph a different width is the whole difference between a
     // font this can wear and one it cannot
     std.mem.writeInt(u16, f[80 + 4 ..][0..2], 1200, .big);
-    {
-        const fd = libc.open(path, .{ .ACCMODE = .WRONLY, .CREAT = true, .TRUNC = true }, @as(c_uint, 0o644));
-        try std.testing.expect(fd >= 0);
-        defer _ = libc.close(fd);
-        try std.testing.expectEqual(@as(isize, f.len), libc.write(fd, &f, f.len));
-    }
+    try writeScratch(path, &f);
     try std.testing.expect(!monospaced(path));
 }
+
+test "a ttc collection is read through its first face" {
+    // The same 92-byte font as above, moved 20 bytes down the file behind a
+    // `ttcf` header naming two faces. Table offsets stay absolute, which is
+    // the property that makes this work at all and the one a hand-rolled
+    // "add the base" would silently break.
+    const base = 20;
+    var f: [base + 92]u8 = @splat(0);
+    @memcpy(f[0..4], "ttcf");
+    std.mem.writeInt(u16, f[4..6], 1, .big); // majorVersion
+    std.mem.writeInt(u32, f[8..12], 2, .big); // numFonts
+    std.mem.writeInt(u32, f[12..16], base, .big); // face 0 lives here
+    std.mem.writeInt(u32, f[16..20], base, .big); // face 1, same tables
+
+    const sfnt = f[base..];
+    std.mem.writeInt(u32, sfnt[0..4], 0x00010000, .big);
+    std.mem.writeInt(u16, sfnt[4..6], 2, .big);
+    @memcpy(sfnt[12..16], "hhea");
+    std.mem.writeInt(u32, sfnt[20..24], base + 44, .big);
+    @memcpy(sfnt[28..32], "hmtx");
+    std.mem.writeInt(u32, sfnt[36..40], base + 80, .big);
+    std.mem.writeInt(u16, sfnt[44 + 34 ..][0..2], 3, .big);
+    for (0..3) |i| std.mem.writeInt(u16, sfnt[80 + i * 4 ..][0..2], 600, .big);
+
+    var path_buf: [64:0]u8 = undefined;
+    const path = scratchFont(&path_buf, ".ttc");
+    defer _ = libc.unlink(path);
+    try writeScratch(path, &f);
+    try std.testing.expect(monospaced(path));
+
+    // A collection claiming no faces has no first one to read.
+    std.mem.writeInt(u32, f[8..12], 0, .big);
+    try writeScratch(path, &f);
+    try std.testing.expect(!monospaced(path));
+}
+
+test "the walk finds this machine's monospace faces" {
+    // Not a fixture: the directory list is the entire platform-specific part
+    // of this file, and a wrong one produces an empty picker rather than an
+    // error. So this asserts against the machine — every OS pardes draws its
+    // own text on ships a monospace face, and finding NONE means the walk is
+    // looking somewhere that does not exist.
+    var arena_state = std.heap.ArenaAllocator.init(std.testing.allocator);
+    defer arena_state.deinit();
+    const found = list(arena_state.allocator(), null);
+    try std.testing.expect(found.len > 0);
+    for (found) |font| {
+        try std.testing.expect(font.name.len > 0);
+        try std.testing.expect(font.path[0] == '/');
+        // The name is the stem, so the file it came from is always longer.
+        try std.testing.expect(std.fs.path.basename(font.path).len > font.name.len);
+    }
+
+    // macOS ships Menlo, and ships it inside a .ttc. It is the one face this
+    // machine can be held to by name, and naming it here is what keeps the
+    // collection branch honest end to end: drop .ttc from the walk, or read a
+    // collection's directory at offset 0, and this is what notices.
+    if (comptime builtin.os.tag == .macos) {
+        const menlo = for (found) |font| {
+            if (std.mem.eql(u8, font.name, "Menlo")) break font;
+        } else return error.MenloMissing;
+        try std.testing.expect(std.mem.endsWith(u8, menlo.path, ".ttc"));
+    }
+}
diff --git a/src/gui/gui.zig b/src/gui/gui.zig
index a03e51ce..c21ad069 100644
--- a/src/gui/gui.zig
+++ b/src/gui/gui.zig
@@ -23,7 +23,7 @@ const look = @import("../look.zig");
 const message = @import("../message.zig");
 const deck = @import("deck.zig");
 const crt = @import("crt.zig");
-const fonts = @import("fonts.zig"); // the Font builtin's half of the seam
+const fonts = @import("../fonts.zig"); // the Font builtin's half of the seam
 const selection_pipe = @import("../selection_pipe.zig");
 
 const is_emscripten = builtin.os.tag == .emscripten;
diff --git a/src/macos.zig b/src/macos.zig
index d463b842..ef68d7e7 100644
--- a/src/macos.zig
+++ b/src/macos.zig
@@ -28,6 +28,14 @@ const look = @import("look.zig");
 const temp_file = @import("temp_file.zig");
 const shell_bin = @import("shell_bin.zig");
 const message = @import("message.zig");
+const nested = @import("nested.zig");
+/// The geometry types the pixel-attachment ABI carries. Behind the same
+/// comptime gate the placements themselves are: a build without MuPDF emits no
+/// attachments, so nothing here is analysed.
+const image = if (pardes.pdf_enabled) @import("image.zig") else struct {};
+const fonts = if (pardes.font_picker) @import("fonts.zig") else struct {
+    pub const want: ?[]const u8 = null;
+};
 const user_config = @import("user_config.zig");
 
 extern "c" fn forkpty(amaster: *c_int, name: ?[*:0]u8, termp: ?*const anyopaque, winp: ?*const posix.winsize) c_int;
@@ -76,6 +84,44 @@ pub const Cell = extern struct {
     flags: u8,
 };
 
+/// Sync with: pardes_image_s. One rasterized attachment — a PDF page, or an
+/// image pane's pixels — and where on the grid it goes.
+///
+/// Geometry travels in PHYSICAL PIXELS, because that is the space the core
+/// already computed it in (pardes_resize hands it the physical cell). `cell_x`
+/// and `cell_y` are the pane BODY's origin in cells and the only thing the
+/// host has to multiply out; `dst` is relative to that origin, and `src` is
+/// the crop of the raster to take. The core has already clipped both to the
+/// viewport, which is what lets a host draw a continuous-scroll page without
+/// inventing an overflow clip of its own.
+pub const Image = extern struct {
+    /// pane lifetime, page and raster generation: together the cache key. A
+    /// host keeps its decoded texture while all three hold still, and `fit`,
+    /// panning and scrolling deliberately do not move them.
+    serial: u32,
+    page: u32,
+    revision: u32,
+    cell_x: u16,
+    cell_y: u16,
+    /// the body this attachment may not paint outside of, in cells
+    cell_w: u16,
+    cell_h: u16,
+    dst_x: u32,
+    dst_y: u32,
+    dst_w: u32,
+    dst_h: u32,
+    src_x: u32,
+    src_y: u32,
+    src_w: u32,
+    src_h: u32,
+    /// subpixel vertical displacement a proportional wheel kept
+    offset_y: f32,
+    iw: u32,
+    ih: u32,
+    /// iw * ih * 4 bytes, RGBA8. Borrowed until the next pardes_frame.
+    rgba: [*]const u8,
+};
+
 /// Sync with: pardes_runtime_s. Two callbacks, because everything else the
 /// core asks for it already does itself — it owns the ptys, and look.openLink
 /// hands URLs to /usr/bin/open. Both are optional at the ABI level: a host that
@@ -108,11 +154,15 @@ const Pty = struct {
 const Msg = union(enum) {
     output: struct { pane: u8, gen: u32, bytes: []u8 },
     eof: struct { pane: u8, gen: u32 },
+    /// One `Look <path>` line from a pardes launched inside this one. Arrives
+    /// on the listener thread; runs, like everything else, on the main one.
+    command: []u8,
 
     fn free(m: Msg, gpa: std.mem.Allocator) void {
         switch (m) {
             .output => |o| gpa.free(o.bytes),
             .eof => {},
+            .command => |c| gpa.free(c),
         }
     }
 };
@@ -156,8 +206,11 @@ const Inbox = struct {
         return removed;
     }
 
-    /// Pty output is lossy under sustained backpressure. EOF is structural:
-    /// admit it by evicting queued output so dead readers are always reaped.
+    /// Pty output is lossy under sustained backpressure. EOF is structural, and
+    /// so is a nested `Look`: one is a reader that must be reaped, the other is
+    /// a launch that already exited believing it was delivered. Admit both by
+    /// evicting queued output. Every switch below is exhaustive on purpose — a
+    /// new message kind has to say which of the two it is.
     fn push(q: *Inbox, gpa: std.mem.Allocator, m: Msg) void {
         q.lock();
         defer q.mutex.unlock();
@@ -166,11 +219,11 @@ const Inbox = struct {
             return;
         }
         if (q.len == q.items.len) {
-            const incoming_eof = switch (m) {
-                .eof => true,
-                .output => false,
+            const lossy = switch (m) {
+                .output => true,
+                .eof, .command => false,
             };
-            if (!incoming_eof) {
+            if (lossy) {
                 m.free(gpa);
                 return;
             }
@@ -178,7 +231,7 @@ const Inbox = struct {
             while (offset < q.len) : (offset += 1)
                 if (switch (q.items[(q.head + offset) % q.items.len]) {
                     .output => true,
-                    .eof => false,
+                    .eof, .command => false,
                 }) break;
             if (offset == q.len) return;
             q.removeAt(offset).free(gpa);
@@ -228,16 +281,51 @@ const State = struct {
     /// loops from those would walk off the buffer.
     frame_cols: u16 = 0,
     frame_rows: u16 = 0,
+    /// This frame's pixel attachments, flattened out of Surface.images. Grown
+    /// and reused like `cells`, and emptied by the same failure path — the
+    /// accessors must never describe a different frame than the cell count.
+    images: []Image = &.{},
+    images_len: usize = 0,
     ptys: [pardes.MAX_PANES]?Pty = @splat(null),
     inbox: Inbox = .{},
     /// Per-slot spawn generation, owned by the main thread. A reader carries a
     /// copy in every message it posts; anything that no longer matches belongs
     /// to a shell this slot has already replaced.
     gens: [pardes.MAX_PANES]u32 = @splat(0),
-    /// Sub-row wheel distance the core has not been told about yet. The core
-    /// moves a whole row at a time, so fractional trackpad travel accumulates
-    /// here and is spent as wheel presses — see pardes_scroll.
+    /// Sub-cell wheel distance the core has not been told about yet, one
+    /// accumulator per axis. The core moves a whole row or column at a time,
+    /// so fractional trackpad travel banks here and is spent as wheel presses
+    /// — see pardes_scroll. Separate axes because a diagonal drift must not
+    /// let one direction's residue push the other over a notch.
     scroll_lag: f32 = 0,
+    scroll_lag_x: f32 = 0,
+    /// Degrees of trackpad rotation not yet spent as a search step — the same
+    /// accumulate-and-keep-the-remainder shape as scroll_lag, see pardes_rotate.
+    rotate_lag: f32 = 0,
+    /// The dial's angular velocity, in degrees per second. While fingers are
+    /// down this is a running estimate off the event stream; when they lift it
+    /// becomes the fling that `coasting` spends. Zero is a dial at rest.
+    rotate_velocity: f32 = 0,
+    /// When the last rotation event arrived, so the estimate above has a dt.
+    rotate_last_ns: i128 = 0,
+    /// Fingers are off and the dial is still turning. Separate from a nonzero
+    /// velocity because during the gesture that velocity is a MEASUREMENT —
+    /// spending it then would double every twist under the hand making it.
+    rotate_coasting: bool = false,
+    /// Panes whose shell has produced output since we last read its cwd.
+    ///
+    /// The cwd is wanted for pane tags and for resolving a relative Look, and
+    /// asking libproc costs a syscall per pane. Polling it on a clock spends
+    /// that forever to notice something that only ever changes when the shell
+    /// runs a command — and a shell that ran a command always writes at least
+    /// its next prompt. So the read is owed to output, not to time: mark here
+    /// on the way past and settle it once at the end of the drain, however
+    /// many chunks that burst arrived in.
+    cwd_stale: [pardes.MAX_PANES]bool = @splat(false),
+    /// The socket a pardes launched inside this app connects to (nested.zig),
+    /// or -1 when it could not be bound and nested launches open their own
+    /// window as they always did.
+    sock_fd: c_int = -1,
     /// Owns the bytes of the user config, which Options only borrows.
     config_arena: std.heap.ArenaAllocator,
 };
@@ -286,8 +374,11 @@ fn initCore(runtime: ?*const Runtime, cols_arg: u16, rows_arg: u16) !void {
     // run before the host can render a frame — so it is read here, before
     // Pardes.init, exactly as src/main.zig does it. The env map is rebuilt from
     // libc's environ because a library has no std.process.Init to inherit one.
-    if (captureEnv(config_arena.allocator())) |*env|
-        opts.startup_config = user_config.load(io, config_arena.allocator(), env);
+    if (captureEnv(config_arena.allocator())) |*env| {
+        const found = user_config.load(io, config_arena.allocator(), env);
+        opts.startup_config = found.bytes;
+        opts.startup_config_path = found.path;
+    }
 
     pardes.image.start(io, allocs.image);
     errdefer pardes.image.stop();
@@ -298,6 +389,12 @@ fn initCore(runtime: ?*const Runtime, cols_arg: u16, rows_arg: u16) !void {
 
     const core = try pardes.Pardes.init(allocs.pardes, opts);
     errdefer core.deinit();
+    // This host draws pixels. Without it the core assumes a terminal that
+    // cannot, and a PDF pane degrades to counted page turns with nothing on
+    // screen at all — which is exactly what it did. The SDL shell sets the
+    // same flag; the tty one sets it from the terminal's kitty-graphics
+    // capability, because there it is a question rather than a fact.
+    core.native_images = true;
 
     // Shells emit OSC 133 prompt marks through these, which is what makes
     // prompt hiding and click-to-move work.
@@ -335,10 +432,52 @@ fn initCore(runtime: ?*const Runtime, cols_arg: u16, rows_arg: u16) !void {
     // the two backends readable side by side.
     _ = drainEffects(st, false);
     for (&st.ptys, 0..) |*slot, id| if (slot.*) |*pt| startReader(st, pt, @intCast(id));
+
+    // Last, because it is the one thing here that publishes this process to
+    // the outside: nothing may connect before the core can answer. The shells
+    // above are already forked, which is why the listener's fd is CLOEXEC —
+    // an orphaned bash holding it would keep the socket bound after we quit.
+    st.sock_fd = nested.listen();
+    if (st.sock_fd >= 0) {
+        const thread = std.Thread.spawn(.{}, lookServer, .{st}) catch |err| {
+            // Bound but unattended would be worse than never bound: every
+            // nested launch would connect, be believed, and vanish.
+            log.warn("nested Look server did not start ({t})", .{err});
+            nested.unlisten(st.sock_fd);
+            st.sock_fd = -1;
+            return;
+        };
+        thread.detach();
+    }
+}
+
+/// Accept `Look <path>` lines from pardes instances launched inside this app
+/// and post them where the main thread will run them.
+///
+/// A detached thread around a call that never returns, exactly like the tty
+/// backend's: close(2) does not release a thread parked in accept(2), so this
+/// dies with the process rather than with the socket. The window that leaves
+/// is one connection accepted between the last tick and process exit posting
+/// into an inbox nobody drains — the same bound the pty readers have, and a
+/// self-pipe to close it would be more machinery than the window is worth.
+fn lookServer(st: *State) void {
+    var buf: [nested.max_line]u8 = undefined;
+    while (nested.acceptLine(st.sock_fd, &buf)) |line| {
+        const owned = st.gpa.dupe(u8, line) catch continue;
+        st.inbox.push(st.gpa, .{ .command = owned });
+        wake(st);
+    }
 }
 
 export fn pardes_deinit() void {
     const st = &(state orelse return);
+    // Before anything else: it is the only fd another process can reach us
+    // through, and unlinking the file is what stops the next launch from
+    // connecting to a session that is halfway through tearing itself down.
+    // The thread parked in accept(2) is not released by this and dies with
+    // the process, which is what its detach() already said.
+    nested.unlisten(st.sock_fd);
+    st.sock_fd = -1;
     // Every reader is joined here, before anything it touches is freed. The
     // runtime joins its tasks on exit, so a reader left parked in read(2) would
     // hang the process instead of the app quitting.
@@ -347,6 +486,7 @@ export fn pardes_deinit() void {
     // would show up as a leak rather than as the shutdown it actually is.
     st.inbox.close(st.gpa);
     if (st.cells.len > 0) st.gpa.free(st.cells);
+    if (st.images.len > 0) st.gpa.free(st.images);
     st.arena.deinit();
     st.core.deinit();
     pardes.image.stop();
@@ -364,14 +504,65 @@ export fn pardes_should_quit() bool {
     return st.core.quit;
 }
 
+/// Something on screen moves on its own and wants ~60 Hz ticks until it stops:
+/// a theme transition fading, or the rotation dial coasting after a flick.
+/// Both are spent by pardes_tick, so this is the host's only cue to keep
+/// pumping — an idle pardes costs nothing precisely because it says false.
 export fn pardes_animating() bool {
     const st = &(state orelse return false);
-    return st.core.themeAnimationActive();
+    return st.core.themeAnimationActive() or st.rotate_coasting;
+}
+
+/// The colour the host should paint everything the grid does not: the window
+/// background behind the titlebar, and behind every pixel of a live resize the
+/// view has not caught up with yet.
+///
+/// The theme's OWN background, not the chrome's, and so not animated — the
+/// same split every other shell draws. Chrome (taglines, the move box, the
+/// scrollbar) fades between themes over a handful of frames; document
+/// backgrounds switch the instant the theme does, and this is one of those.
+///
+/// PARDES_COLOR_DEFAULT means the active theme declares NO background of its
+/// own (`bg = null`: the curated `dark`, and every vendored `*_transparent`).
+/// In a terminal that means "wear whatever the terminal is wearing"; a window
+/// has nothing to wear, so the host lets its own backdrop through — see the
+/// NSVisualEffectView in AppDelegate.
+export fn pardes_theme_bg() u32 {
+    // Before pardes_init there is no session, but there IS a theme: the ring's
+    // first entry is what the core boots wearing, so answering with it keeps
+    // the window from opening one colour and flipping to another a frame later.
+    const th = if (state) |*st| st.core.theme() else &pardes.themes[0];
+    const bg = th.bg orelse return color_default;
+    return @as(u32, bg[0]) << 16 | @as(u32, bg[1]) << 8 | bg[2];
+}
+
+/// Re-read the cwd of every shell that just spoke, and only those.
+///
+/// A pane's tag shows this and a relative `Look` resolves against it, so it has
+/// to follow the shell around rather than stay at the directory the pane was
+/// spawned in. The tty and SDL hosts poll all of them every frame; here the
+/// drain has just said exactly which shells produced bytes, and nothing else
+/// can have changed one — a `cd` is a command, and a shell that ran a command
+/// writes at least its next prompt. So an idle session costs nothing at all,
+/// and a busy one costs one libproc call per pane per burst.
+fn refreshCwds(st: *State) void {
+    for (&st.cwd_stale, 0..) |*stale, id| {
+        if (!stale.*) continue;
+        stale.* = false;
+        const pt = st.ptys[id] orelse continue;
+        var buf: [1024]u8 = undefined;
+        if (look.shellCwd(pt.pid, &buf)) |wd| st.core.setCwd(id, wd);
+    }
 }
 
 /// Drain what the reader tasks collected into the core, then perform whatever
-/// the core queued in response. Returns whether anything moved, so an idle
-/// wakeup does not cost the host a repaint.
+/// the core queued in response. Returns whether this tick did any IO.
+///
+/// NOT a repaint signal, however tempting: the core changes the grid on its own
+/// for a cursor move, a selection, a mode change and a scroll, none of which
+/// queue an effect or read a pty, so all four return false here. The macOS host
+/// learned that the expensive way — see the comment on pump() in
+/// src/macos/Sources/AppDelegate.swift.
 export fn pardes_tick() bool {
     const st = &(state orelse return false);
     // Cleared before the drain: a reader that pushes during this tick must be
@@ -384,6 +575,7 @@ export fn pardes_tick() bool {
         switch (msg) {
             .output => |o| {
                 if (st.gens[o.pane] != o.gen) continue;
+                st.cwd_stale[o.pane] = true;
                 st.core.update(.{ .output = .{ .pane = o.pane, .bytes = o.bytes } });
             },
             .eof => |e| {
@@ -394,12 +586,39 @@ export fn pardes_tick() bool {
                 reap(st, e.pane);
                 st.core.update(.{ .eof = .{ .pane = e.pane } });
             },
+            // Already filtered down to `Look ` by the accept side — this
+            // socket may open things and that is all it may do.
+            .command => |c| st.core.update(.{ .command = c }),
         }
     }
+    refreshCwds(st);
     if (drainEffects(st, true)) changed = true;
-    // A live theme transition repaints on its own clock; say so, or the host
-    // stops ticking and the fade freezes half-applied.
-    if (st.core.themeAnimationActive()) changed = true;
+    // ...and ADVANCE the transition, which is the whole reason the host keeps
+    // ticking. The tty and SDL loops call `core.update(.tick)` on their own
+    // clocks; this host has no loop of its own, so the pump IS the clock — and
+    // without this the fade never moved: `chromeTheme()` stayed on the OLD
+    // theme's chrome forever, so every tagline kept its previous colours until
+    // the next launch, and `themeAnimationActive()` never went false, so the
+    // 16 ms re-pump in AppDelegate.pump spun for the rest of the session.
+    if (st.core.themeAnimationActive()) {
+        st.core.update(.tick);
+        changed = true;
+    }
+    // ...and the dial, for the same reason and off the same clock: one frame
+    // of coast per tick, decayed, until it is slower than a notch a second.
+    if (st.rotate_coasting) {
+        spendRotation(st, st.rotate_velocity * rotation_fling_step);
+        st.rotate_velocity *= rotation_fling_decay;
+        if (@abs(st.rotate_velocity) < rotation_fling_stop) {
+            st.rotate_velocity = 0;
+            st.rotate_coasting = false;
+            // The remainder dies with the gesture: a banked half-notch
+            // surviving into the next twist is the hysteresis `rotate 0`
+            // exists to clear.
+            st.rotate_lag = 0;
+        }
+        changed = true;
+    }
     return changed;
 }
 
@@ -456,13 +675,12 @@ export fn pardes_mouse(button_arg: c_int, kind_arg: c_int, col: u16, row: u16, m
     } });
 }
 
-export fn pardes_scroll(delta_rows: f32, col: u16, row: u16) void {
+export fn pardes_scroll(delta_rows: f32, delta_cols: f32, col: u16, row: u16) void {
     const st = &(state orelse return);
-    const ticks = takeScrollTicks(&st.scroll_lag, delta_rows);
-    var left = ticks;
-    while (left != 0) {
-        const down = left > 0;
-        left += if (down) -1 else 1;
+    var down_left = takeScrollTicks(&st.scroll_lag, delta_rows);
+    while (down_left != 0) {
+        const down = down_left > 0;
+        down_left += if (down) -1 else 1;
         st.core.update(.{ .mouse = .{
             .button = if (down) .wheel_down else .wheel_up,
             .kind = .press,
@@ -470,6 +688,115 @@ export fn pardes_scroll(delta_rows: f32, col: u16, row: u16) void {
             .row = row,
         } });
     }
+    // Horizontal after vertical, and through the same quantizer: the core's
+    // own drift guard (config.wheelTick) is what decides whether a sideways
+    // wobble during a vertical flick counts, so the shell must not second-guess
+    // it by filtering here.
+    var right_left = takeScrollTicks(&st.scroll_lag_x, delta_cols);
+    while (right_left != 0) {
+        const right = right_left > 0;
+        right_left += if (right) -1 else 1;
+        st.core.update(.{ .mouse = .{
+            .button = if (right) .wheel_right else .wheel_left,
+            .kind = .press,
+            .col = col,
+            .row = row,
+        } });
+    }
+}
+
+/// Spend a trackpad rotation as search steps. AppKit reports degrees since the
+/// last event, counterclockwise positive; the core has no rotation, so the
+/// dial is quantized into the keys a hand would otherwise press — clockwise is
+/// `n` (forward through the matches), counterclockwise `N`.
+export fn pardes_rotate(degrees: f32) void {
+    const st = &(state orelse return);
+    // A gesture beginning re-zeros the dial: leftover travel from the last
+    // twist must not make the first degree of this one jump a match — and it
+    // catches a fling still coasting, because a finger back down is how a hand
+    // catches a dial.
+    if (degrees == 0) {
+        st.rotate_lag = 0;
+        st.rotate_velocity = 0;
+        st.rotate_coasting = false;
+        st.rotate_last_ns = monotonicNs();
+        return;
+    }
+    noteRotationVelocity(st, degrees);
+    spendRotation(st, degrees);
+}
+
+/// The fingers lifted. What happens next is decided entirely by how fast they
+/// were moving when they did: `rotationFling` subtracts the floor, so a slow
+/// twist stops dead where it was put and a flick keeps going in proportion to
+/// how hard it was thrown.
+export fn pardes_rotate_end() void {
+    const st = &(state orelse return);
+    const last = st.rotate_last_ns;
+    st.rotate_last_ns = 0;
+    st.rotate_coasting = false;
+    // A hand that turned the dial, STOPPED, and then lifted has released at
+    // rest however fast it was moving before — and the last sample is still
+    // sitting there saying otherwise. Without this the most deliberate twist
+    // of all (turn, look at it, let go) is the one that flings.
+    if (last == 0 or monotonicNs() - last > 90 * std.time.ns_per_ms) {
+        st.rotate_velocity = 0;
+        return;
+    }
+    st.rotate_velocity = rotationFling(st.rotate_velocity);
+    st.rotate_coasting = st.rotate_velocity != 0;
+}
+
+/// Monotonic nanoseconds, the clock lsp_zls.zig already times with. Monotonic
+/// and not REALTIME on purpose: a dial that flung because NTP stepped the wall
+/// clock backwards would be a bug nobody ever reproduces.
+///
+/// Zero on failure, which is also the "no sample yet" sentinel — so a clock
+/// that will not answer makes the dial refuse to fling rather than fling on a
+/// garbage dt.
+fn monotonicNs() i128 {
+    var ts: libc.timespec = undefined;
+    if (libc.clock_gettime(.MONOTONIC, &ts) != 0) return 0;
+    return @as(i128, ts.sec) * std.time.ns_per_s + ts.nsec;
+}
+
+/// One event's contribution to the velocity estimate, in degrees per second.
+/// Smoothed, because a single 120 Hz sample of a human wrist is mostly noise
+/// and the fling would otherwise be decided by whichever one happened to land
+/// last.
+fn noteRotationVelocity(st: *State, degrees: f32) void {
+    const now = monotonicNs();
+    const last = st.rotate_last_ns;
+    st.rotate_last_ns = now;
+    st.rotate_coasting = false;
+    if (last == 0 or now == 0) return;
+    const dt_ns = now - last;
+    // A gap this long is a gesture nobody announced the start of, not a slow
+    // one: dividing by it would report a crawl and eat a real fling.
+    if (dt_ns <= 0 or dt_ns > 200 * std.time.ns_per_ms) return;
+    const seconds: f32 = @floatCast(@as(f64, @floatFromInt(dt_ns)) / @as(f64, std.time.ns_per_s));
+    const sample = degrees / seconds;
+    if (!std.math.isFinite(sample)) return;
+    st.rotate_velocity = st.rotate_velocity * 0.35 + sample * 0.65;
+}
+
+/// Turn degrees into whole search steps, keeping the remainder. The one place
+/// the dial reaches the core, so a hand-turned notch and a coasted one are the
+/// same keystroke by construction.
+fn spendRotation(st: *State, degrees: f32) void {
+    var left = takeRotationNotches(&st.rotate_lag, degrees);
+    while (left != 0) {
+        const back = left > 0; // counterclockwise
+        left += if (back) -1 else 1;
+        st.core.update(.{ .key = .{ .cp = if (back) 'N' else 'n' } });
+    }
+}
+
+export fn pardes_command(text_ptr: ?[*]const u8, len: usize) void {
+    const st = &(state orelse return);
+    const text: []const u8 = if (text_ptr) |p| p[0..len] else "";
+    if (text.len == 0) return;
+    st.core.update(.{ .command = text });
 }
 
 export fn pardes_resize(cols_arg: u16, rows_arg: u16, cell_w: u16, cell_h: u16) void {
@@ -491,12 +818,13 @@ export fn pardes_resize(cols_arg: u16, rows_arg: u16, cell_w: u16, cell_h: u16)
 export fn pardes_frame() u32 {
     const st = &(state orelse return 0);
     _ = st.arena.reset(.retain_capacity);
-    // The three accessors below must never describe a different frame than the
-    // count this returns, so a failure empties all of them together rather than
+    // The accessors below must never describe a different frame than the count
+    // this returns, so a failure empties all of them together rather than
     // leaving last frame's buffer behind a fresh cols/rows.
     st.frame_len = 0;
     st.frame_cols = 0;
     st.frame_rows = 0;
+    st.images_len = 0;
     const surface = st.core.render(st.arena.allocator()) catch |err| {
         log.err("render failed: {t}", .{err});
         return 0;
@@ -528,9 +856,78 @@ export fn pardes_frame() u32 {
         };
         if (cell.default) out.text[0] = ' ' else @memcpy(out.text[0..cell.len], cell.grapheme());
     }
+    collectImages(st, surface);
     return @intCast(count);
 }
 
+/// Flatten Surface.images into the flat C array the host walks.
+///
+/// A dropped attachment is a page that does not draw, never a wrong one, so
+/// every failure here just stops collecting: the frame is still valid, it
+/// simply has fewer pictures in it than the core offered.
+fn collectImages(st: *State, surface: *const pardes.Surface) void {
+    if (comptime !pardes.pdf_enabled) return;
+    if (surface.nimages == 0) return;
+    if (st.images.len < surface.nimages) {
+        const resized = if (st.images.len == 0)
+            st.gpa.alloc(Image, surface.nimages)
+        else
+            st.gpa.realloc(st.images, surface.nimages);
+        st.images = resized catch return;
+    }
+    for (surface.images[0..surface.nimages]) |maybe| {
+        const place = maybe orelse continue;
+        if (place.iw == 0 or place.ih == 0 or place.rgba.len == 0) continue;
+        // Continuous documents hand over geometry the core already clipped to
+        // the viewport. Anything else (a static image pane) is the whole
+        // raster scaled into the whole body, which is the same two rectangles
+        // spelled without a crop.
+        const geometry = place.native.geometry orelse image.NativeGeometry{
+            .src = .{ .x = 0, .y = 0, .w = @intCast(place.iw), .h = @intCast(place.ih) },
+            .dst = .{
+                .x = 0,
+                .y = 0,
+                .w = @as(u32, place.w) * st.core.cell_pixels.w,
+                .h = @as(u32, place.h) * st.core.cell_pixels.h,
+            },
+        };
+        if (geometry.dst.w == 0 or geometry.dst.h == 0) continue;
+        if (geometry.src.w == 0 or geometry.src.h == 0) continue;
+        st.images[st.images_len] = .{
+            .serial = place.serial,
+            .page = place.native.page,
+            .revision = place.native.revision,
+            .cell_x = place.x,
+            .cell_y = place.y,
+            .cell_w = place.w,
+            .cell_h = place.h,
+            .dst_x = geometry.dst.x,
+            .dst_y = geometry.dst.y,
+            .dst_w = geometry.dst.w,
+            .dst_h = geometry.dst.h,
+            .src_x = geometry.src.x,
+            .src_y = geometry.src.y,
+            .src_w = geometry.src.w,
+            .src_h = geometry.src.h,
+            .offset_y = place.native.pixel_offset_y,
+            .iw = @intCast(place.iw),
+            .ih = @intCast(place.ih),
+            .rgba = place.rgba.ptr,
+        };
+        st.images_len += 1;
+    }
+}
+
+export fn pardes_frame_images() u32 {
+    const st = &(state orelse return 0);
+    return @intCast(st.images_len);
+}
+
+export fn pardes_frame_image_list() ?[*]const Image {
+    const st = &(state orelse return null);
+    return if (st.images_len == 0) null else st.images.ptr;
+}
+
 export fn pardes_frame_cells() ?[*]const Cell {
     const st = &(state orelse return null);
     return if (st.frame_len == 0) null else st.cells.ptr;
@@ -561,6 +958,77 @@ export fn pardes_cursor_bar() bool {
     return if (st.core.surface.cursor) |c| c.bar else false;
 }
 
+/// The acme verb the core last performed, and clears it. Ordinals, not the
+/// enum: the host is not part of this build, so the boundary speaks integers
+/// and the ABI guard asserts they are the ones the header names.
+export fn pardes_take_haptic() c_int {
+    const st = &(state orelse return 0);
+    return switch (st.core.takeHaptic()) {
+        .none => 0,
+        .exec => 1,
+        .look => 2,
+    };
+}
+
+/// The file the `Font` builtin asked for, and clears it — the same take-once
+/// shape as the haptic above, and the same one the SDL shell uses on this
+/// exact variable.
+///
+/// A copy rather than the borrowed slice: `fonts.want` is a length and no
+/// terminator, and C wants a string. One static buffer because there is one
+/// core and the header promises the value only until the next call.
+var font_path_z: [4096:0]u8 = undefined;
+
+export fn pardes_font_take() ?[*:0]const u8 {
+    _ = state orelse return null;
+    if (comptime !pardes.font_picker) return null;
+    const want = fonts.want orelse return null;
+    fonts.want = null;
+    if (want.len >= font_path_z.len) return null;
+    @memcpy(font_path_z[0..want.len], want);
+    font_path_z[want.len] = 0;
+    return &font_path_z;
+}
+
+/// The FILE behind the focused pane, or null when there is none — a terminal,
+/// an output buffer (`+Search` names a directory, not a document), or nothing
+/// focused at all. A PDF and an image both count: they are real paths on disk,
+/// and the titlebar's proxy icon is about the file, not about who can edit it.
+///
+/// A copy into a static buffer for the reason pardes_font_take keeps one: the
+/// core owns a length and no terminator, C wants a string, and there is one
+/// core. Valid until the next call.
+var active_path_z: [4096:0]u8 = undefined;
+
+export fn pardes_active_path() ?[*:0]const u8 {
+    const st = &(state orelse return null);
+    const path = activeFilePath(st) orelse return null;
+    if (path.len == 0 or path.len >= active_path_z.len) return null;
+    @memcpy(active_path_z[0..path.len], path);
+    active_path_z[path.len] = 0;
+    return &active_path_z;
+}
+
+/// Does the focused pane hold edits that are not on disk? False for everything
+/// that cannot be saved in the first place, which is the same set
+/// pardes_active_path answers null for minus the PDFs and images — those have
+/// a path but no buffer, so they are never dirty.
+export fn pardes_active_dirty() bool {
+    const st = &(state orelse return false);
+    const pane = st.core.panes[st.core.active] orelse return false;
+    const f = if (pane.file) |*x| x else return false;
+    if (f.output != null) return false;
+    return f.revision != f.saved_revision;
+}
+
+fn activeFilePath(st: *State) ?[]const u8 {
+    const pane = st.core.panes[st.core.active] orelse return null;
+    if (pane.file) |*f| return if (f.output == null) f.path else null;
+    if (comptime pardes.pdf_enabled) if (pane.pdfPath()) |path| return path;
+    if (pane.image) |*iv| return iv.path;
+    return null;
+}
+
 // ---------------------------------------------------------------- effects
 
 /// Perform the IO the core queued. `threads_ok` is false for the one drain
@@ -812,10 +1280,7 @@ fn encodeAttrs(style: pardes.CellStyle) u16 {
 
 /// Spend accumulated sub-row travel as whole wheel notches, keeping the
 /// remainder. The core has no fractional scroll — both other shells do this
-/// same accumulation host-side (stepScroll in gui.zig, the drain loop in
-/// web/app.mjs) — so it lives here and the Swift side stays a translator.
-///
-/// The lag is clamped to one screen's worth so a nonsense delta (an inertial
+/// too — and the clamp is so that an absurd delta (a momentum-phase kinetic
 /// fling reported in points, a NaN) cannot spin the emit loop.
 fn takeScrollTicks(lag: *f32, delta_rows: f32) i32 {
     if (!std.math.isFinite(delta_rows)) return 0;
@@ -826,6 +1291,65 @@ fn takeScrollTicks(lag: *f32, delta_rows: f32) i32 {
     return whole;
 }
 
+/// One search step per this many degrees of twist. Every notch is a jump to
+/// another match, so it stays coarse enough that a thumb resettling cannot
+/// walk the cursor across the file — but 20 degrees was more than a wrist
+/// gives without thinking about it, and the dial felt stuck. Ten is still a
+/// deliberate twist, and 36 steps to a full turn.
+const rotation_notch_degrees: f32 = 10;
+
+/// Where momentum STARTS, in degrees per second — and it starts at zero.
+///
+/// The fling is the release speed MINUS this, so a slow twist coasts not a
+/// little but not at all, and the faster the flick the more there is. A plain
+/// threshold would hand out two free notches the instant it was crossed, which
+/// is the one thing a dial must not do: the same gesture, a hair quicker,
+/// jumping twice as far is how a control stops feeling like a control.
+const rotation_fling_floor: f32 = 70;
+/// ...and the ceiling on what is left after that subtraction. AppKit reports a
+/// thousand degrees a second for one frame of a twitch, and this cap is what
+/// decides how far the hardest possible flick throws the list: 400 deg/s is
+/// about 111 degrees of coast, so eleven matches. Twenty read as the list
+/// getting away from you.
+const rotation_fling_max: f32 = 400;
+/// One pump of coasting. Fixed rather than measured: the host re-pumps at
+/// ~60 Hz for exactly as long as pardes_animating says to, and a fixed step
+/// makes one fling spend the same travel every time — which is what lets a
+/// golden assert it instead of asserting the machine's timer jitter.
+const rotation_fling_step: f32 = 1.0 / 60.0;
+/// Per-step decay. 0.94 at 60 Hz is a little over half a second of coast, the
+/// same order as the trackpad's own inertial scrolling.
+const rotation_fling_decay: f32 = 0.94;
+/// Below this the dial is at rest: one notch a second is not momentum, it is a
+/// list still stepping long after the hand has moved on.
+const rotation_fling_stop: f32 = 18;
+
+/// The velocity a release at `speed` degrees/second actually coasts at, after
+/// the floor is subtracted and the remainder capped. Zero means the twist was
+/// a placement, not a throw — which is most of them.
+///
+/// Total travel follows from it and the decay as a geometric series:
+/// `v * step / (1 - decay)`, i.e. about 0.28 degrees per degree/second. A
+/// 200 deg/s release therefore coasts ~36 degrees, three or four notches.
+fn rotationFling(speed: f32) f32 {
+    const excess = @min(@abs(speed) - rotation_fling_floor, rotation_fling_max);
+    if (excess < rotation_fling_stop) return 0;
+    return std.math.copysign(excess, speed);
+}
+
+/// Spend accumulated rotation as whole search steps, keeping the remainder.
+/// Same contract as takeScrollTicks, including the clamp: an absurd delta
+/// spends a bounded number of notches instead of spinning the emit loop.
+fn takeRotationNotches(lag: *f32, degrees: f32) i32 {
+    if (!std.math.isFinite(degrees)) return 0;
+    const limit = rotation_notch_degrees * 64;
+    const next = std.math.clamp(lag.* + degrees, -limit, limit);
+    if (!std.math.isFinite(next)) return 0;
+    const whole: i32 = @intFromFloat(@trunc(next / rotation_notch_degrees));
+    lag.* = next - @as(f32, @floatFromInt(whole)) * rotation_notch_degrees;
+    return whole;
+}
+
 // ---------------------------------------------------------------- ABI guard
 
 // The header is hand-written, so nothing but a test keeps it honest. build.zig
@@ -857,14 +1381,24 @@ test "pardes.h declares every export the way it is defined" {
     try expectSameAbi(@TypeOf(c.pardes_paste), @TypeOf(pardes_paste));
     try expectSameAbi(@TypeOf(c.pardes_mouse), @TypeOf(pardes_mouse));
     try expectSameAbi(@TypeOf(c.pardes_scroll), @TypeOf(pardes_scroll));
+    try expectSameAbi(@TypeOf(c.pardes_rotate), @TypeOf(pardes_rotate));
+    try expectSameAbi(@TypeOf(c.pardes_rotate_end), @TypeOf(pardes_rotate_end));
+    try expectSameAbi(@TypeOf(c.pardes_command), @TypeOf(pardes_command));
     try expectSameAbi(@TypeOf(c.pardes_resize), @TypeOf(pardes_resize));
     try expectSameAbi(@TypeOf(c.pardes_frame), @TypeOf(pardes_frame));
     try expectSameAbi(@TypeOf(c.pardes_frame_cells), @TypeOf(pardes_frame_cells));
     try expectSameAbi(@TypeOf(c.pardes_frame_cols), @TypeOf(pardes_frame_cols));
     try expectSameAbi(@TypeOf(c.pardes_frame_rows), @TypeOf(pardes_frame_rows));
+    try expectSameAbi(@TypeOf(c.pardes_frame_images), @TypeOf(pardes_frame_images));
+    try expectSameAbi(@TypeOf(c.pardes_frame_image_list), @TypeOf(pardes_frame_image_list));
     try expectSameAbi(@TypeOf(c.pardes_cursor_x), @TypeOf(pardes_cursor_x));
     try expectSameAbi(@TypeOf(c.pardes_cursor_y), @TypeOf(pardes_cursor_y));
     try expectSameAbi(@TypeOf(c.pardes_cursor_bar), @TypeOf(pardes_cursor_bar));
+    try expectSameAbi(@TypeOf(c.pardes_take_haptic), @TypeOf(pardes_take_haptic));
+    try expectSameAbi(@TypeOf(c.pardes_font_take), @TypeOf(pardes_font_take));
+    try expectSameAbi(@TypeOf(c.pardes_active_path), @TypeOf(pardes_active_path));
+    try expectSameAbi(@TypeOf(c.pardes_active_dirty), @TypeOf(pardes_active_dirty));
+    try expectSameAbi(@TypeOf(c.pardes_theme_bg), @TypeOf(pardes_theme_bg));
 }
 
 test "pardes.h matches the Zig boundary" {
@@ -878,6 +1412,12 @@ test "pardes.h matches the Zig boundary" {
     try expectEqual(@offsetOf(c.pardes_cell_s, "attrs"), @offsetOf(Cell, "attrs"));
     try expectEqual(@offsetOf(c.pardes_cell_s, "len"), @offsetOf(Cell, "len"));
     try expectEqual(@offsetOf(c.pardes_cell_s, "flags"), @offsetOf(Cell, "flags"));
+    // The attachment struct is a wide one and every field is read by hand on
+    // the Swift side, so its layout is checked at both ends rather than at the
+    // two that happen to be easy.
+    try expectEqual(@sizeOf(c.pardes_image_s), @sizeOf(Image));
+    inline for (@typeInfo(Image).@"struct".fields) |field|
+        try expectEqual(@offsetOf(c.pardes_image_s, field.name), @offsetOf(Image, field.name));
     try expectEqual(@sizeOf(c.pardes_runtime_s), @sizeOf(Runtime));
 
     try expectEqual(@as(u32, c.PARDES_COLOR_DEFAULT), color_default);
@@ -914,6 +1454,12 @@ test "pardes.h matches the Zig boundary" {
     try expectEqual(c.PARDES_MOUSE_MOTION, @intFromEnum(pardes.Mouse.Kind.motion));
     try expectEqual(c.PARDES_MOUSE_DRAG, @intFromEnum(pardes.Mouse.Kind.drag));
 
+    // The haptic ordinals pardes_take_haptic returns, against the header's
+    // names and the core's enum. Three places, checked as one.
+    try expectEqual(c.PARDES_HAPTIC_NONE, @intFromEnum(pardes.Haptic.none));
+    try expectEqual(c.PARDES_HAPTIC_EXEC, @intFromEnum(pardes.Haptic.exec));
+    try expectEqual(c.PARDES_HAPTIC_LOOK, @intFromEnum(pardes.Haptic.look));
+
     // The attribute bits the host decodes, against the encoder that writes them.
     try expectEqual(@as(u16, c.PARDES_ATTR_BOLD), encodeAttrs(.{ .bold = true }));
     try expectEqual(@as(u16, c.PARDES_ATTR_DIM), encodeAttrs(.{ .dim = true }));
@@ -957,3 +1503,66 @@ test "sub-row scroll spends whole notches and keeps the remainder" {
     try expectEqual(@as(f32, 0), lag);
     try expectEqual(@as(i32, 256), takeScrollTicks(&lag, 1e9));
 }
+
+test "trackpad rotation spends whole search steps and keeps the remainder" {
+    const expectEqual = std.testing.expectEqual;
+    var lag: f32 = 0;
+    // A twist under one notch moves nothing; crossing it moves exactly one,
+    // and the overshoot is credited to the next.
+    try expectEqual(@as(i32, 0), takeRotationNotches(&lag, 7));
+    try expectEqual(@as(i32, 1), takeRotationNotches(&lag, 5));
+    try expectEqual(@as(f32, 2), lag);
+
+    // Reversing spends the residue first, so a twist back is not amplified by
+    // travel the other direction already banked.
+    try expectEqual(@as(i32, -1), takeRotationNotches(&lag, -12));
+    try expectEqual(@as(f32, 0), lag);
+
+    // One deliberate half-turn is several matches, not a hundred.
+    lag = 0;
+    try expectEqual(@as(i32, 18), takeRotationNotches(&lag, 180));
+
+    // Garbage moves nothing and leaves the dial usable; an absurd delta is
+    // clamped rather than spinning the emit loop.
+    lag = 0;
+    try expectEqual(@as(i32, 0), takeRotationNotches(&lag, std.math.nan(f32)));
+    try expectEqual(@as(i32, 0), takeRotationNotches(&lag, -std.math.inf(f32)));
+    try expectEqual(@as(f32, 0), lag);
+    try expectEqual(@as(i32, 64), takeRotationNotches(&lag, 1e9));
+}
+
+test "the dial flings in proportion to the release, and not at all when placed" {
+    // The whole point of the curve: momentum ramps UP FROM ZERO at the floor
+    // rather than switching on at it, so no release speed exists where the
+    // same gesture a hair quicker suddenly jumps several matches further.
+    try std.testing.expectEqual(@as(f32, 0), rotationFling(0));
+    try std.testing.expectEqual(@as(f32, 0), rotationFling(40));
+    try std.testing.expectEqual(@as(f32, 0), rotationFling(rotation_fling_floor));
+    // Just over the floor is still nothing: what is left has to beat the
+    // at-rest threshold before it is worth waking the pump for.
+    try std.testing.expectEqual(@as(f32, 0), rotationFling(rotation_fling_floor + 5));
+
+    // ...and past that it is linear in the release speed, both ways.
+    try std.testing.expectEqual(@as(f32, 130), rotationFling(200));
+    try std.testing.expectEqual(@as(f32, -130), rotationFling(-200));
+
+    // A twitch is capped rather than emptying the list.
+    try std.testing.expectEqual(rotation_fling_max, rotationFling(100_000));
+    try std.testing.expectEqual(-rotation_fling_max, rotationFling(-100_000));
+
+    // What that buys, in the units a hand feels: total coast is the geometric
+    // series v*step/(1-decay), so a brisk 200 deg/s release is a few matches
+    // and the hardest flick the cap allows is bounded well short of a hundred.
+    const travel = struct {
+        fn of(speed: f32) f32 {
+            return @abs(rotationFling(speed)) * rotation_fling_step / (1 - rotation_fling_decay);
+        }
+    }.of;
+    try std.testing.expect(travel(200) / rotation_notch_degrees < 5);
+    try std.testing.expect(travel(200) / rotation_notch_degrees >= 3);
+    // ...and the hardest flick a trackpad can report is bounded at about a
+    // dozen matches. This is the number to change if the dial ever feels like
+    // it is getting away from the hand.
+    try std.testing.expect(travel(100_000) / rotation_notch_degrees < 12);
+    try std.testing.expect(travel(100_000) / rotation_notch_degrees > 8);
+}
diff --git a/src/macos/Info.plist b/src/macos/Info.plist
index 9e8f65f7..3d526242 100644
--- a/src/macos/Info.plist
+++ b/src/macos/Info.plist
@@ -10,11 +10,67 @@
 	<string>pardes</string>
 	<key>CFBundlePackageType</key>
 	<string>APPL</string>
+	<!-- The version the About panel shows, and the build Launch Services
+	     compares when two copies of the bundle are on disk. -->
+	<key>CFBundleShortVersionString</key>
+	<string>0.1.0</string>
+	<key>CFBundleVersion</key>
+	<string>1</string>
+	<!-- No extension: Launch Services appends .icns and looks in
+	     Contents/Resources, where build.zig installs the pardes.icns
+	     src/macos/icon.swift draws. Without this key the Dock shows the blank
+	     generic app even though the icon is sitting right there in the bundle. -->
+	<key>CFBundleIconFile</key>
+	<string>pardes</string>
 	<key>NSHighResolutionCapable</key>
 	<true/>
+	<!-- build.zig stamps this from macos_min_version, which is the single
+	     source of truth, into a copy of this file; the key must exist for
+	     plutil's -replace to have something to replace. -->
 	<key>LSMinimumSystemVersion</key>
 	<string>13.0</string>
+	<key>LSApplicationCategoryType</key>
+	<string>public.app-category.developer-tools</string>
 	<key>NSPrincipalClass</key>
 	<string>NSApplication</string>
+	<!-- Both false, and neither is boilerplate: there are live ptys with child
+	     processes attached and unsaved buffers with no autosave behind them, so
+	     a process macOS killed or quietly relaunched would lose work and orphan
+	     shells. -->
+	<key>NSSupportsAutomaticTermination</key>
+	<false/>
+	<key>NSSupportsSuddenTermination</key>
+	<false/>
+	<!-- What Finder's "Open With" offers pardes for. Editor rather than Viewer
+	     because Save is a builtin: pardes writes the files it opens. A folder
+	     is a legitimate target too — Look on a directory opens a directory
+	     pane, which is how you navigate in acme. -->
+	<key>CFBundleDocumentTypes</key>
+	<array>
+		<dict>
+			<key>CFBundleTypeName</key>
+			<string>Text Document</string>
+			<key>CFBundleTypeRole</key>
+			<string>Editor</string>
+			<key>LSHandlerRank</key>
+			<string>Alternate</string>
+			<key>LSItemContentTypes</key>
+			<array>
+				<string>public.plain-text</string>
+			</array>
+		</dict>
+		<dict>
+			<key>CFBundleTypeName</key>
+			<string>Folder</string>
+			<key>CFBundleTypeRole</key>
+			<string>Editor</string>
+			<key>LSHandlerRank</key>
+			<string>Alternate</string>
+			<key>LSItemContentTypes</key>
+			<array>
+				<string>public.folder</string>
+			</array>
+		</dict>
+	</array>
 </dict>
 </plist>
diff --git a/src/macos/Sources/AppDelegate.swift b/src/macos/Sources/AppDelegate.swift
index 4df5899c..cda35ff0 100644
--- a/src/macos/Sources/AppDelegate.swift
+++ b/src/macos/Sources/AppDelegate.swift
@@ -1,31 +1,57 @@
 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!
     private var view: PardesView!
+    /// The blur behind the grid, shown only while the theme declares no
+    /// background of its own. See applyTheme.
+    private var backdrop: NSVisualEffectView!
     // One pump chain at a time. pump() re-arms itself while a theme transition
     // is in flight and every input pumps as well, so without this a burst of
     // 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(
@@ -38,18 +64,67 @@ final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
         // isReleasedWhenClosed on would have AppKit release it out from under
         // that reference the moment the close button is pressed.
         window.isReleasedWhenClosed = false
-        window.contentView = view
+        // The grid and the blur are SIBLINGS in a plain container, not parent
+        // and child. A transparent theme has to show something through the
+        // grid, and AppKit will not blur what is behind a window unless an
+        // NSVisualEffectView asks it to — but the backdrop is hidden for every
+        // theme that brings its own background, and hiding a superview hides
+        // its subviews with it. Nested, an opaque theme drew a blank window.
+        let container = NSView(frame: NSRect(origin: .zero, size: want))
+        container.autoresizesSubviews = true
+        backdrop = NSVisualEffectView(frame: container.bounds)
+        // .underWindowBackground is the material meant for exactly this — the
+        // full-window wash behind content, rather than the sidebar/HUD
+        // materials that carry their own tint. .behindWindow is what samples
+        // the desktop instead of the window's own layers.
+        backdrop.material = .underWindowBackground
+        backdrop.blendingMode = .behindWindow
+        // .active, not .followsWindowActiveState: the grid stays readable when
+        // the window is not key, and a backdrop that flattens to grey on focus
+        // loss makes an unfocused pardes look switched off.
+        backdrop.state = .active
+        backdrop.autoresizingMask = [.width, .height]
+        view.frame = container.bounds
+        view.autoresizingMask = [.width, .height]
+        // Order matters: the blur is BEHIND the grid.
+        container.addSubview(backdrop)
+        container.addSubview(view, positioned: .above, relativeTo: backdrop)
+        window.contentView = container
 
         // 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
+        // What the core is wearing, not a constant agreed by hand — two things
+        // draw and both have to say the same thing: 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 that agreement
+        // the gap flashes on every drag. It also owns window.appearance: a dark
+        // window with a light-mode titlebar reads as a bug, and so does the
+        // reverse the moment someone wears `acme`.
+        applyTheme()
         // 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 +135,10 @@ 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 +175,14 @@ 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 +190,316 @@ 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
+    }
+
+    /// Dress the WINDOW in what the core is wearing: the background AppKit
+    /// paints where the view does not (the titlebar, and the strip a live
+    /// resize outruns), and the blur behind a theme that brings no background
+    /// of its own.
+    ///
+    /// Cheap enough to call every pump: the view compares before it dirties
+    /// itself, and the window properties are written only when the answer
+    /// moved. `dressed` is what makes the FIRST call unconditional — a boot
+    /// theme whose background happened to equal the view's starting guess
+    /// would otherwise leave the window in AppKit's default clothes forever.
+    private var dressed = false
+
+    private func applyTheme() {
+        let changed = view.adoptThemeBG(pardes_theme_bg())
+        guard changed || !dressed else { return }
+        dressed = true
+        if let rgb = view.themeBG {
+            backdrop.isHidden = true
+            window.isOpaque = true
+            window.backgroundColor = NSColor(
+                srgbRed: CGFloat((rgb >> 16) & 0xFF) / 255,
+                green: CGFloat((rgb >> 8) & 0xFF) / 255,
+                blue: CGFloat(rgb & 0xFF) / 255,
+                alpha: 1)
+            // ...and follow the theme into light mode, so the titlebar, the
+            // traffic lights and the resize cursor stop belonging to a
+            // different application than the grid under them. Luminance off
+            // the same sRGB channels the grid is drawn with.
+            let luma = (0.2126 * CGFloat((rgb >> 16) & 0xFF)
+                + 0.7152 * CGFloat((rgb >> 8) & 0xFF)
+                + 0.0722 * CGFloat(rgb & 0xFF)) / 255
+            window.appearance = NSAppearance(named: luma > 0.5 ? .aqua : .darkAqua)
+        } else {
+            // Transparent: the window stops painting anything of its own and
+            // the blur takes over. isOpaque false is what lets the desktop
+            // reach the backdrop at all — a titled window is opaque by default
+            // and would composite over it.
+            backdrop.isHidden = false
+            window.isOpaque = false
+            window.backgroundColor = .clear
+            window.appearance = NSAppearance(named: .darkAqua)
+        }
+    }
+
+    /// The focused pane, in the titlebar: the proxy icon macOS lets you drag
+    /// and Cmd-click for the path, and the dot in the close button that means
+    /// unsaved.
+    ///
+    /// A pure read-out — the window says what the core already decided, and
+    /// nothing here can change it. There is no document ARCHITECTURE behind it
+    /// and deliberately so: no NSDocument, no save panel, no "do you want to
+    /// save" on close. Save is a builtin, the pane's tag says so, and this is
+    /// the same two facts spelled where a Mac user looks for them.
+    ///
+    /// Cached, because setting representedURL makes AppKit hit the filesystem
+    /// for the icon and this runs on every pump.
+    private var shownPath: String?
+    private var shownDirty = false
+
+    private func applyDocument() {
+        let path = pardes_active_path().map { String(cString: $0) }
+        if path != shownPath {
+            shownPath = path
+            // A terminal or an output buffer is not a document: no path means
+            // no proxy icon, rather than a stale one from the last file pane.
+            window.representedURL = path.map { URL(fileURLWithPath: $0) }
+            // ...and the title goes with it. A proxy icon beside a title that
+            // names something else reads as a bug, and AppKit will not fill the
+            // title in for us while `title` has been set by hand. The window is
+            // a SESSION and not a document, so it falls back to the app's own
+            // name the moment focus lands somewhere with no file behind it.
+            window.title = path.map { ($0 as NSString).lastPathComponent } ?? "pardes"
+        }
+        let dirty = pardes_active_dirty()
+        if dirty != shownDirty {
+            shownDirty = dirty
+            window.isDocumentEdited = dirty
+        }
     }
 
     @objc private func inputArrived(_ notification: Notification) {
@@ -128,7 +510,54 @@ 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
+        // After the tick, because a `Theme` command runs inside it and the
+        // window has to follow the grid in the same frame rather than at the
+        // next launch.
+        applyTheme()
+        applyDocument()
+
+        // 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 +602,15 @@ 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..3d841a60 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 +23,71 @@
 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
+let pardesDefaultFG: UInt32 = 0xCC_CC_CC
+let pardesDefaultBG: UInt32 = 0x12_12_12
 
-private let inputNotification = Notification.Name("pardesDidInput")
+/// Pinned sRGB for rasterized attachments, so a PDF page's bytes mean the same
+/// thing here as they do in the SDL shell. DeviceRGB is the fallback rather
+/// than a crash: a machine with no sRGB profile is not a reason to stop
+/// drawing pages.
+private let sRGB: CGColorSpace = CGColorSpace(name: CGColorSpace.sRGB) ?? CGColorSpaceCreateDeviceRGB()
 
 // UNVERIFIED: kCTFontAttributeName bridged through NSAttributedString.Key. It is
 // the same string as .font, but spelling the CoreText key means the value stays
@@ -60,18 +123,41 @@ private func decodeColor(_ encoded: UInt32, _ fallback: UInt32) -> UInt32 {
     return encoded & UInt32(PARDES_COLOR_RGB_MASK)
 }
 
-/// `block` means the filled cursor sits on this cell.
+/// 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))!
+    }
+}
+
+/// A background run that must not be painted at all, so the window's own
+/// backdrop shows through. Outside the 24-bit RGB range, so it can never
+/// collide with a real colour, and distinct from the `.max` the run loop
+/// flushes on.
+let bgClear: UInt32 = 0x0100_0000
+
+/// `block` means the filled cursor sits on this cell. `ground` is what a
+/// DEFAULT background resolves to, and `clearGround` asks for those cells to
+/// come back as `bgClear` instead of a colour.
 private func resolve(
     _ cell: pardes_cell_s,
-    block: Bool
+    block: Bool,
+    ground: UInt32,
+    clearGround: Bool
 ) -> (fg: UInt32, bg: UInt32, alpha: CGFloat, visible: Bool) {
     // 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
+            ? (ground, pardesDefaultFG, 1, false)
+            : (pardesDefaultFG, clearGround ? bgClear : ground, 1, false)
     }
-    var fg = decodeColor(cell.fg, defaultFG)
-    var bg = decodeColor(cell.bg, defaultBG)
+    let bgDefault = cell.bg == UInt32(PARDES_COLOR_DEFAULT)
+    var fg = decodeColor(cell.fg, pardesDefaultFG)
+    var bg = decodeColor(cell.bg, ground)
     // 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.
@@ -85,6 +171,9 @@ private func resolve(
     // The other shells scale the channels by 6/10. Over a dark background alpha
     // lands in the same place and costs one blend instead of three multiplies.
     let alpha: CGFloat = cell.attrs & UInt16(PARDES_ATTR_DIM) != 0 ? 0.6 : 1
+    // Only an UNREVERSED default background is the ground. A reverse puts the
+    // text colour there, and text is a real colour that paints.
+    if clearGround && bgDefault && !reverse { bg = bgClear }
     return (fg, bg, alpha, visible)
 }
 
@@ -97,6 +186,134 @@ 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]]
+
+    /// Round `v` onto the backing grid: `scale` is the display's
+    /// backingScaleFactor, so at 2x this lands on half-points, which are whole
+    /// device pixels.
+    private static func snap(_ v: CGFloat, _ scale: CGFloat, _ rule: FloatingPointRoundingRule) -> CGFloat {
+        (v * scale).rounded(rule) / scale
+    }
+
+    init(size: CGFloat, path: String?, scale: CGFloat) {
+        let face = Metrics.face(size: size, path: path)
+        let scale = max(1, scale)
+
+        // 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])]
+
+        // The grid has to land on WHOLE DEVICE PIXELS, and that is the whole
+        // constraint — a fractional column boundary makes the background pass
+        // (which runs with antialiasing off, or touching fills seam) wobble by
+        // a pixel from column to column, and on a screen made of tag bars and
+        // selections that stripe is visible.
+        //
+        // Whole POINTS is how that used to be spelled, and on a Retina display
+        // it asks for twice what it needs: half a point IS a whole pixel at 2x.
+        // The difference is not academic — Monaco advances 8.4014pt at 14, so
+        // ceiling to 9 spaced every column 7.1% wider than the face was drawn
+        // for, which is loose, washed-out text that reads as bad rendering.
+        // Snapped to the backing grid it is 8.5, i.e. +1.2%.
+        //
+        // Width rounds to NEAREST — a monospace glyph is drawn to fit its own
+        // advance, so the half-pixel either way is slack — while height rounds
+        // UP, because losing a pixel off a descender is clipping.
+        let snap = Metrics.snap
+        fonts = faces
+        // The ascent lands on a pixel for a second reason: it is the baseline's
+        // offset inside the cell, so the rules hung off it are whole-pixel
+        // fills rather than one-pixel bars smeared across two rows.
+        ascent = max(1 / scale, snap(CTFontGetAscent(face), scale, .toNearestOrAwayFromZero))
+        cellWidth = max(1 / scale, snap(advance(face, 0x4D), scale, .toNearestOrAwayFromZero))
+        cellHeight = max(1 / scale, snap(CTFontGetAscent(face) + CTFontGetDescent(face) + CTFontGetLeading(face), scale, .up))
+        ruleThickness = max(1 / scale, snap(CTFontGetUnderlineThickness(face), scale, .toNearestOrAwayFromZero))
+        underlineOffset = snap(CTFontGetUnderlinePosition(face), scale, .toNearestOrAwayFromZero)
+        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 +323,174 @@ 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 backingScaleFactor `metrics` was snapped to, so a move between a
+    /// Retina and a 1x display re-measures the cell instead of leaving the grid
+    /// aligned to the other screen's pixels.
+    private var metricsScale: CGFloat = 2
 
-        // 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])
+    /// The active theme's own background, or nil when it declares none — the
+    /// `*_transparent` themes and the curated `dark`. Nil is not a colour to
+    /// substitute but a decision: the ground stops being painted at all, the
+    /// view stops being opaque, and AppDelegate's NSVisualEffectView shows
+    /// through it. Read off pardes_theme_bg() once per pump, which is also
+    /// what makes a `Theme` command take hold without a relaunch.
+    private(set) var themeBG: UInt32? = pardesDefaultBG
 
-        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)
+    /// Adopt what the core is wearing. Returns whether anything moved, so the
+    /// host only reconfigures the window when it has to.
+    @discardableResult
+    func adoptThemeBG(_ encoded: UInt32) -> Bool {
+        let wanted: UInt32? =
+            encoded == UInt32(PARDES_COLOR_DEFAULT) ? nil : encoded & UInt32(PARDES_COLOR_RGB_MASK)
+        guard wanted != themeBG else { return false }
+        themeBG = wanted
+        needsDisplay = true
+        return true
+    }
+
+    // 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
+
+    init(fontSize size: CGFloat) {
+        // No window yet, so no backing scale to ask for: 2x is the guess every
+        // Mac shipped this decade would give, and viewDidChangeBackingProperties
+        // below re-measures the moment there is a real answer — including the
+        // 1x case, which a bare guess would otherwise leave wrong forever.
+        let built = Metrics(size: size, path: nil, scale: 2)
+        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)
+        // Files dropped ON the grid. Finder and the Dock already reach the app
+        // through application(_:open:), but that path cannot say WHERE — and
+        // where is the whole difference between "a file opened somewhere" and
+        // acme's "a file opened next to the pane I pointed at".
+        registerForDraggedTypes([.fileURL])
+        // 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 scale = window?.backingScaleFactor ?? metricsScale
+        let next = Metrics(size: size, path: path, scale: scale)
+        // 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
+        metricsScale = scale
+        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 }
+    // Opaque only while the theme brings its own background. A transparent
+    // theme has none, and an opaque view over a visual-effect backdrop is a
+    // grey rectangle where the blur should be.
+    override var isOpaque: Bool { themeBG != nil }
     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 +508,13 @@ 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)
+        // The ground, from the core rather than from a constant agreed by hand.
+        // A transparent theme has none: CLEAR rather than fill, because AppKit
+        // does not blank a non-opaque view and last frame's pixels would
+        // otherwise pile up on themselves.
+        let ground = themeBG ?? pardesDefaultBG
+        let clearGround = themeBG == nil
+        if clearGround { ctx.clear(bounds) } else { fill(ctx, bounds, ground, 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
@@ -194,17 +532,23 @@ final class PardesView: NSView {
             let base = row * cols
             let y = CGFloat(row) * cellHeight
             var start = 0
-            var color = resolve(cells[base], block: blockY == row && blockX == 0).bg
+            var color = resolve(cells[base], block: blockY == row && blockX == 0,
+                                ground: ground, clearGround: clearGround).bg
             for col in 1...cols {
                 // A real color is 24 bits, so .max is a sentinel that cannot
                 // compare equal and therefore always flushes the last run.
                 let next: UInt32 = col == cols
                     ? .max
-                    : resolve(cells[base + col], block: blockY == row && blockX == col).bg
+                    : resolve(cells[base + col], block: blockY == row && blockX == col,
+                              ground: ground, clearGround: clearGround).bg
                 if next == color { continue }
-                fill(ctx, CGRect(x: CGFloat(start) * cellWidth, y: y,
-                                 width: CGFloat(col - start) * cellWidth, height: cellHeight),
-                     color, 1)
+                // bgClear runs are the ground showing through, and the ground is
+                // already clear — painting them would be painting the hole shut.
+                if color != bgClear {
+                    fill(ctx, CGRect(x: CGFloat(start) * cellWidth, y: y,
+                                     width: CGFloat(col - start) * cellWidth, height: cellHeight),
+                         color, 1)
+                }
                 start = col
                 color = next
             }
@@ -215,96 +559,282 @@ 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 and the ascent is
+        // whole points (see Metrics), so every baseline is already on a pixel:
+        // letting CoreText place a glyph 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)
+        // Grayscale antialiasing, never LCD subpixel. Smoothing needs to know
+        // the colour behind the glyph, which over a transparent theme's
+        // backdrop it cannot — the result is coloured fringing that reads as
+        // blur. macOS has defaulted this off since 10.14, but the user can turn
+        // it back on globally and it is not their call to make for this grid.
+        ctx.setShouldSmoothFonts(false)
         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()
 
+        // Pixel attachments over the grid: rasterized PDF pages, and image
+        // panes' own pixels. After the glyphs, the way the SDL shell draws them
+        // after its cells — a PDF pane's cells are blank, so the order only
+        // matters for the tag row an attachment must never reach, and the clip
+        // below is what keeps it off.
+        drawImages(ctx)
+
         if bar {
             let x = Int(pardes_cursor_x()), y = Int(pardes_cursor_y())
             if x >= 0, y >= 0, x < cols, y < rows {
                 // 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
+                let fg = resolve(cells[y * cols + x], block: false,
+                                 ground: themeBG ?? pardesDefaultBG, clearGround: 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)
+            }
+        }
+    }
+
+    /// What identifies a decoded raster: the pane's lifetime, the page, and the
+    /// generation MuPDF last rendered. Panning, zooming to fit and scrolling
+    /// deliberately move none of them, so the CGImage survives all three.
+    private struct ImageKey: Hashable {
+        let serial: UInt32
+        let page: UInt32
+        let revision: UInt32
+    }
+
+    /// Rasterized attachments, decoded once each. The bytes the core lends are
+    /// only valid until the next `pardes_frame`, so the CGImage owns a COPY —
+    /// which is exactly why the cache has to be keyed well enough that the copy
+    /// happens when the pixels change and never on an ordinary scroll.
+    private var imageCache: [ImageKey: CGImage] = [:]
+
+    private func drawImages(_ ctx: CGContext) {
+        let count = Int(pardes_frame_images())
+        guard count > 0, let list = pardes_frame_image_list() else {
+            // Nothing on screen owns pixels any more: the pages a closed pane
+            // rendered would otherwise sit in here for the rest of the session.
+            if !imageCache.isEmpty { imageCache.removeAll(keepingCapacity: true) }
+            return
+        }
+
+        // The core computed every rectangle in PHYSICAL pixels, because that is
+        // what pardes_resize handed it. The view draws in points.
+        let scale = max(1, metricsScale)
+        var live = Set<ImageKey>()
+        live.reserveCapacity(count)
+
+        ctx.setShouldAntialias(true)
+        for i in 0..<count {
+            let place = list[i]
+            let key = ImageKey(serial: place.serial, page: place.page, revision: place.revision)
+            live.insert(key)
+            guard let full = image(for: place, key: key) else { continue }
+            guard let crop = full.cropping(to: CGRect(
+                x: Int(place.src_x), y: Int(place.src_y),
+                width: Int(place.src_w), height: Int(place.src_h)))
+            else { continue }
+
+            // The body is the rectangle nothing may paint past. The core has
+            // already clipped the geometry to the viewport, but a tagline is
+            // not the viewport — a page one pixel too tall would sit on it.
+            let body = CGRect(
+                x: CGFloat(place.cell_x) * cellWidth, y: CGFloat(place.cell_y) * cellHeight,
+                width: CGFloat(place.cell_w) * cellWidth, height: CGFloat(place.cell_h) * cellHeight)
+            let dst = CGRect(
+                x: body.minX + CGFloat(place.dst_x) / scale,
+                y: body.minY + (CGFloat(place.dst_y) + CGFloat(place.offset_y)) / scale,
+                width: CGFloat(place.dst_w) / scale,
+                height: CGFloat(place.dst_h) / scale)
+
+            ctx.saveGState()
+            ctx.clip(to: body)
+            // isFlipped gives us a y-down CTM and CGImage draws +y up, so a
+            // plain ctx.draw would land every page upside down. Flip about the
+            // destination rather than about the view, so the arithmetic above
+            // stays in the grid's own coordinates.
+            ctx.translateBy(x: dst.minX, y: dst.maxY)
+            ctx.scaleBy(x: 1, y: -1)
+            // A page is resampled whenever fit or zoom disagrees with the
+            // raster MuPDF last produced; nearest-neighbour text is unreadable.
+            ctx.interpolationQuality = .high
+            ctx.draw(crop, in: CGRect(x: 0, y: 0, width: dst.width, height: dst.height))
+            ctx.restoreGState()
+        }
+
+        // Evict what this frame did not place. Scrolling a document past a page
+        // is the common case, and holding every page a session ever showed is
+        // how a PDF viewer ends up owning a gigabyte of decoded bitmaps.
+        if imageCache.count > live.count {
+            imageCache = imageCache.filter { live.contains($0.key) }
+        }
+    }
+
+    /// The decoded raster for one attachment, made once per generation.
+    private func image(for place: pardes_image_s, key: ImageKey) -> CGImage? {
+        if let cached = imageCache[key] { return cached }
+        let bytes = Int(place.iw) * Int(place.ih) * 4
+        guard bytes > 0, let rgba = place.rgba else { return nil }
+        // Copied, not referenced: the core lends these bytes until the next
+        // pardes_frame and this image outlives many of them.
+        guard let data = CFDataCreate(nil, rgba, bytes),
+              let provider = CGDataProvider(data: data)
+        else { return nil }
+        // Straight alpha, R,G,B,A in memory — the same bytes the SDL shell
+        // uploads as R8G8B8A8_UNORM and blends with ONE_MINUS_SRC_ALPHA.
+        let made = CGImage(
+            width: Int(place.iw), height: Int(place.ih),
+            bitsPerComponent: 8, bitsPerPixel: 32, bytesPerRow: Int(place.iw) * 4,
+            space: sRGB,
+            bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.last.rawValue | CGBitmapInfo.byteOrder32Big.rawValue),
+            provider: provider, decode: nil, shouldInterpolate: true, intent: .defaultIntent)
+        if let made { imageCache[key] = made }
+        return made
+    }
+
+    /// 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 }
+            // clearGround: false — this pass only reads `fg`, and a glyph is
+            // never the hole in the ground.
+            let style = resolve(cell, block: blockCol == col,
+                                ground: themeBG ?? pardesDefaultBG, clearGround: false)
+            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()
     }
 
-    private func drawCell(
+    /// 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 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),
+            // Rounded like every other rule offset: a third of the ascent is a
+            // fraction, and a fractional one-pixel bar is a two-pixel smear.
+            fill(ctx, CGRect(x: x, y: baseline + (metrics.ascent * 0.3).rounded(), 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 +849,87 @@ 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()
+    }
+
+    /// The fingers came off the trackpad. A post-decode entry point of its own
+    /// so the e2e harness can throw the dial: NSEvent phases have no public
+    /// constructor, and a fling nothing can synthesize is a fling nothing can
+    /// assert.
+    func rotateEnd() {
+        pardes_rotate_end()
+        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 +981,188 @@ 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 and the momentum, exactly as it owns the scroll accumulator.
+    ///
+    /// AppKit gives rotation no momentum phase of its own — `momentumPhase` is
+    /// scroll's alone — so the fling is measured from the release speed on the
+    /// Zig side rather than handed to us. All this has to get right is telling
+    /// it where the gesture starts and stops.
+    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 —
+        // and stops a fling still coasting, because a finger back down is how
+        // a hand catches a dial.
+        if event.phase == .began { pardes_rotate(0) }
+        rotate(degrees: CGFloat(event.rotation))
+        // .cancelled too: a gesture the system took away should not fling.
+        if event.phase == .ended || event.phase == .cancelled { rotateEnd() }
+    }
+
+    /// 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))
     }
 
-    private func cell(for event: NSEvent) -> (col: UInt16, row: UInt16)? {
+    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 +1170,68 @@ 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: - files dropped on the grid
+
+    /// A drop is a CLICK followed by `Look`, and that is the whole definition.
+    ///
+    /// The core has no notion of a drop and is not being given one: the pointer
+    /// lands where it landed, which focuses that pane exactly as a left click
+    /// there would, and then the ordinary `Look` builtin runs in it — so the
+    /// document opens beside the pane you pointed at rather than beside
+    /// whichever one happened to be focused. Drop on a tag and you clicked a
+    /// tag; there is no case to special-case, and nothing here the hand could
+    /// not have done itself.
+    override func draggingEntered(_ sender: NSDraggingInfo) -> NSDragOperation {
+        // AppKit reuses this answer for draggingUpdated when that is not
+        // implemented, so the cursor stays right for the whole drag.
+        droppedFiles(sender).isEmpty ? [] : .copy
+    }
+
+    override func performDragOperation(_ sender: NSDraggingInfo) -> Bool {
+        let paths = droppedFiles(sender)
+        guard !paths.isEmpty else { return false }
+        drop(paths, at: cellAt(convert(sender.draggingLocation, from: nil)))
+        return true
+    }
+
+    /// The drop, decoded: paths and a cell, nothing AppKit left in it.
+    ///
+    /// Split out for the reason every gesture here is — `NSDraggingInfo` is a
+    /// protocol with a dozen members and no public conformer, so a test that
+    /// had to build one would be testing its own stub. The decision lives one
+    /// call below the event, and `drop` in test/macos_e2e.swift drives exactly
+    /// this.
+    ///
+    /// A nil cell is a drop before the first frame, which has no grid to point
+    /// at: the files still open, they just open where focus already was.
+    func drop(_ paths: [String], at target: GridPoint?) {
+        if let target {
+            press(PARDES_MOUSE_LEFT, at: target)
+            release(PARDES_MOUSE_LEFT, at: target)
+        }
+        // Whole tail, unquoted: executeBuiltinLine takes everything after the
+        // first word as the argument, so a path with spaces in it needs no
+        // escaping and would in fact break under any.
+        for path in paths {
+            let line = "Look \(path)"
+            line.withCString { pardes_command($0, line.utf8.count) }
+        }
+        fed()
+    }
+
+    /// File paths on the drag pasteboard, in order. Empty for anything else,
+    /// which is also how draggingEntered decides whether to accept at all.
+    private func droppedFiles(_ sender: NSDraggingInfo) -> [String] {
+        let options: [NSPasteboard.ReadingOptionKey: Any] = [.urlReadingFileURLsOnly: true]
+        guard let urls = sender.draggingPasteboard.readObjects(
+            forClasses: [NSURL.self], options: options) as? [URL]
+        else { return [] }
+        return urls.map(\.path)
     }
 
     // MARK: - geometry
@@ -448,6 +1247,12 @@ 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
@@ -462,17 +1267,27 @@ final class PardesView: NSView {
 
     // Dragging the window between a Retina display and a 1x one changes the
     // backing scale without moving a single bound, so setFrameSize above never
-    // fires and the physical cell metrics the core uses to place PDF pages stay
-    // at the old scale forever. This is the only notification of it. (Ghostty
-    // hooks the same one, and additionally re-fires from the window's
-    // didChangeScreen notification, which AppKit does not always pair with it.)
+    // fires. This is the only notification of it. (Ghostty hooks the same one,
+    // and additionally re-fires from the window's didChangeScreen
+    // notification, which AppKit does not always pair with it.)
+    //
+    // TWO things depend on the scale: the physical cell metrics the core uses
+    // to place PDF pages, and the cell itself, which is snapped to whole
+    // DEVICE pixels (see Metrics) and is therefore aligned to the display it
+    // was measured on. Re-measuring reports the resize on its own, so the
+    // delegate call is the else-branch and not an extra one.
     override func viewDidChangeBackingProperties() {
         super.viewDidChangeBackingProperties()
-        delegate?.pardesViewDidResize(self)
+        if let scale = window?.backingScaleFactor, scale != metricsScale {
+            wear(size: fontSize, path: fontPath)
+        } else {
+            delegate?.pardesViewDidResize(self)
+        }
     }
 }
 
 // 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.
diff --git a/src/macos/build-app.sh b/src/macos/build-app.sh
deleted file mode 100755
index 6734f8d3..00000000
--- a/src/macos/build-app.sh
+++ /dev/null
@@ -1,45 +0,0 @@
-#!/bin/sh
-# Assemble pardes.app from libpardes.a and the Swift sources. Run it through
-# `zig build macos-app -Dplatform=macos`, or by hand with the install prefix as
-# $1 once `zig build -Dplatform=macos` has produced the library.
-#
-# There is no Xcode project on purpose. An .app is a directory with a plist and
-# a binary in it, swiftc ships with the Command Line Tools, and a hand-written
-# pbxproj would be a second build system to keep in step for no gain at this
-# stage. What Xcode buys — an xcframework of universal slices, codesigning,
-# notarization, a DMG — is distribution machinery; see docs/macos.md for the
-# upgrade path when that day comes.
-set -eu
-
-root=$(cd "$(dirname "$0")/../.." && pwd)
-out=${1:-"$root/zig-out"}
-app="$out/pardes.app"
-lib="$out/lib/libpardes.a"
-
-[ -f "$lib" ] || { echo "missing $lib — run: zig build -Dplatform=macos" >&2; exit 1; }
-command -v swiftc >/dev/null || { echo "swiftc not found (needs macOS + Command Line Tools)" >&2; exit 1; }
-
-rm -rf "$app"
-mkdir -p "$app/Contents/MacOS" "$app/Contents/Resources"
-cp "$root/src/macos/Info.plist" "$app/Contents/Info.plist"
-
-# -import-objc-header rather than a module map: the header is consumed straight
-# from the source tree, so there is nothing to stage and nothing to keep in
-# sync. A module map is what an xcframework needs, and there isn't one.
-#
-# -lc++ because ghostty-vt pulls in simdutf and highway, which are C++. The Zig
-# side bundles compiler_rt/ubsan_rt into the archive (see build.zig), so the
-# C++ runtime is the only thing left for this link to supply.
-# -target is not optional. Without it swiftc uses the host triple, so
-# LC_BUILD_VERSION records whatever macOS built the thing and dyld refuses to
-# launch it on anything older — the Info.plist's LSMinimumSystemVersion is a
-# claim, not the enforcement. It is also what turns on the availability
-# diagnostics that catch a post-13 API before a user does.
-swiftc -O -target "$(uname -m)-apple-macos13.0" \
-	-import-objc-header "$root/src/macos/pardes.h" \
-	-o "$app/Contents/MacOS/pardes" \
-	"$root"/src/macos/Sources/*.swift \
-	"$lib" -lc++ \
-	-framework AppKit -framework CoreText -framework CoreGraphics
-
-echo "built $app"
diff --git a/src/macos/build-e2e.sh b/src/macos/build-e2e.sh
new file mode 100755
index 00000000..c0f9613c
--- /dev/null
+++ b/src/macos/build-e2e.sh
@@ -0,0 +1,52 @@
+#!/bin/sh
+# Link the offscreen end-to-end harness: the app's own Swift shell, plus
+# test/macos_e2e.swift as the entry point, against the same libpardes.a. Run it
+# through `zig build macos-e2e -Dplatform=macos`, or by hand with the install
+# prefix as $1 and the deployment target as $2.
+#
+# A SECOND BINARY rather than a `--e2e` flag on the app, for two reasons.
+#
+# Test scaffolding does not ship inside the product. A flag would put the script
+# interpreter, the /tmp world-builder and the golden differ into the thing a
+# user launches, and would give the app a mode in which it rewrites files under
+# /tmp and calls exit() — none of which anyone should be one argv typo away from.
+#
+# And src/macos/Sources/main.swift holds top-level code, which IS an entry
+# point: a module cannot contain both top-level statements and a @main type, so
+# the harness could not join that link even if the first reason went away. Every
+# other Swift file the app builds from is compiled here, so this link is also
+# what proves the shell still compiles as a library rather than as an app.
+set -eu
+
+root=$(cd "$(dirname "$0")/../.." && pwd)
+out=${1:-"$root/zig-out"}
+# Keep in step with macos_min_version in build.zig, which passes it in. The
+# default is only for a by-hand run. Same string the app's own link uses, and
+# for the same reason: -target is what decides LC_BUILD_VERSION and turns on
+# the availability diagnostics.
+minver=${2:-13.0}
+lib="$out/lib/libpardes.a"
+bin="$out/bin/pardes-macos-e2e"
+
+[ -f "$lib" ] || { echo "missing $lib — run: zig build -Dplatform=macos" >&2; exit 1; }
+command -v swiftc >/dev/null || { echo "swiftc not found (needs macOS + Command Line Tools)" >&2; exit 1; }
+
+mkdir -p "$out/bin"
+
+# -import-objc-header and -lc++ are the app link's, unchanged, and have to stay
+# that way: this link exists to exercise the app's link, so anything that
+# differs here is something the harness cannot vouch for.
+#
+# -O for the same reason. A debug build of the CoreText pass and the effect
+# drain settles on different timings than a user sees, and `stable` waits on
+# exactly those timings.
+swiftc -O -target "$(uname -m)-apple-macos$minver" \
+	-import-objc-header "$root/src/macos/pardes.h" \
+	-o "$bin" \
+	"$root/src/macos/Sources/PardesView.swift" \
+	"$root/src/macos/Sources/AppDelegate.swift" \
+	"$root/test/macos_e2e.swift" \
+	"$lib" -lc++ \
+	-framework AppKit -framework CoreText -framework CoreGraphics
+
+echo "built $bin"
diff --git a/src/macos/icon.swift b/src/macos/icon.swift
new file mode 100644
index 00000000..2e775660
--- /dev/null
+++ b/src/macos/icon.swift
@@ -0,0 +1,307 @@
+// Draws pardes.app's icon at build time and hands the result to iconutil.
+//
+// The mark is GLENDA, the Plan 9 rabbit — pardes is an acme, and acme is
+// Plan 9's, so the bunny is the lineage stated in one shape. She is drawn out
+// of the terminal's own palette rather than traced from a bitmap: the ground
+// is defaultBG, the strip she sits under is the tag bar, and she herself is
+// defaultFG. That is also why this is generated instead of committed — a
+// checked-in .icns is a binary blob that stops matching the app the first time
+// one of those colours moves, silently, with nothing in a diff to catch it.
+//
+// build.zig compiles this file alone into a cached binary and runs it with the
+// bundle's Resources directory as argv[1]; Info.plist's CFBundleIconFile names
+// the pardes.icns that comes out. Compiled alone is also what makes top-level
+// code legal here: one file, one module, its own binary.
+//
+// Byte-identical output for byte-identical input is a requirement, not a
+// nicety — an icns that churns on every build is a bundle that churns on every
+// build, and Launch Services notices. Hence a pinned sRGB colour space, integer
+// geometry, and nothing read from the clock or the environment.
+
+import CoreGraphics
+import Foundation
+import ImageIO
+import UniformTypeIdentifiers
+
+/// Every failure path lands here. A build that ships the generic blank-page
+/// icon looks like an app nobody finished, so half-drawn is worse than absent
+/// and build.zig has this exit code waiting: a bundle whose icon did not draw
+/// should not have built.
+func die(_ message: String) -> Never {
+    fputs("icon.swift: \(message)\n", stderr)
+    exit(1)
+}
+
+struct RGB {
+    let red: CGFloat
+    let green: CGFloat
+    let blue: CGFloat
+
+    init(_ hex: UInt32) {
+        red = CGFloat((hex >> 16) & 0xFF) / 255
+        green = CGFloat((hex >> 8) & 0xFF) / 255
+        blue = CGFloat(hex & 0xFF) / 255
+    }
+
+    func components(_ alpha: CGFloat) -> [CGFloat] { [red, green, blue, alpha] }
+}
+
+// Straight out of PardesView.swift. If those move these move, because the icon
+// is a picture of the running program and a stale picture is worse than none:
+// it looks deliberate.
+let bodyTop = RGB(0x12_12_12)      // defaultBG
+let bodyBottom = RGB(0x0A_0A_0A)   // defaultBG, shaded
+let tagBar = RGB(0x34_65_A4)       // ansi16[4], the muted blue
+let text = RGB(0xCC_CC_CC)         // defaultFG
+let cursor = RGB(0xFC_E9_4F)       // ansi16[11], bright yellow
+
+// Apple's icon grid rather than the whole square: the artwork is a rounded
+// square floating in a transparent margin, 824 of 1024 with a 185.4 corner
+// radius in the template — 80.47% of the canvas, and 22.37% of the SQUARE, not
+// of the canvas, which would over-round it by a quarter. Filling the canvas
+// edge to edge is the loudest tell that an app was not built on a Mac.
+let squareFraction: CGFloat = 0.8047
+let cornerFraction: CGFloat = 0.2237
+
+// GLENDA, as ellipses. Four for the silhouette, filled as ONE path so the
+// overlaps vanish under nonzero winding and she is a single shape rather than
+// four stuck together, then two eyes punched back out in the ground colour.
+//
+// Ellipses and not a traced outline for the reason everything else here is a
+// fraction: the mark has to survive being twelve pixels across. An outlined
+// drawing at that size is a grey smudge with a lighter grey inside it, whereas
+// a silhouette is still a rabbit — the two ears are the whole recognition, and
+// they are the two shapes that reach furthest from the mass.
+let tagHeight: CGFloat = 0.165
+
+/// Her box: the body square under the tag bar, inset so the ears are not
+/// welded to the strip and the haunch is not welded to the bottom corners.
+let stageTop: CGFloat = 0.250
+let stageBottom: CGFloat = 0.950
+let stageInset: CGFloat = 0.135
+
+/// One ellipse of her, in fractions of that box: centre, radii, and a tilt in
+/// degrees about its own centre. Fractions rather than points because the same
+/// numbers have to describe the mark at 16 pixels and at 1024.
+struct Blob {
+    let cx: CGFloat
+    let cy: CGFloat
+    let rx: CGFloat
+    let ry: CGFloat
+    let tilt: CGFloat
+
+    init(_ cx: CGFloat, _ cy: CGFloat, _ rx: CGFloat, _ ry: CGFloat, tilt: CGFloat = 0) {
+        self.cx = cx
+        self.cy = cy
+        self.rx = rx
+        self.ry = ry
+        self.tilt = tilt
+    }
+
+    func path(in stage: CGRect) -> CGPath {
+        let box = CGRect(
+            x: -stage.width * rx, y: -stage.height * ry,
+            width: stage.width * rx * 2, height: stage.height * ry * 2)
+        var placement = CGAffineTransform(
+            translationX: stage.minX + stage.width * cx,
+            y: stage.minY + stage.height * cy
+        ).rotated(by: tilt * .pi / 180)
+        return CGPath(ellipseIn: box, transform: &placement)
+    }
+}
+
+// The ears overlap the head and the head overlaps the haunch on purpose: each
+// pair has to still intersect after rounding at 16 pixels, or she comes apart
+// into floating pieces at exactly the size nobody would look twice at.
+let silhouette: [Blob] = [
+    Blob(0.325, 0.150, 0.080, 0.200, tilt: -12),  // left ear
+    Blob(0.675, 0.150, 0.080, 0.200, tilt: 12),  // right ear
+    Blob(0.500, 0.490, 0.245, 0.212),  // head
+    Blob(0.500, 0.785, 0.268, 0.215),  // haunch
+]
+
+// Set wide and low in the head, which is the whole of her expression. Rounder
+// than a dot and smaller than the classic drawing's, because a big oval eye
+// closes up into a grey blur two sizes down.
+let eyes: [Blob] = [
+    Blob(0.393, 0.468, 0.056, 0.070),
+    Blob(0.607, 0.468, 0.056, 0.070),
+]
+
+/// Wider than it is tall, sitting just under the eyes: the one shape that says
+/// rabbit rather than cat. Punched in the ground colour like the eyes.
+let nose = Blob(0.500, 0.605, 0.045, 0.030)
+
+// ...and the block cursor, parked at the end of the tag bar. The palette's
+// last entry, and the only warm thing in the icon: pardes is still an acme,
+// and this is the two pixels that say so above her head.
+let cursorWidth: CGFloat = 0.072
+let cursorRightPad: CGFloat = 0.120
+
+/// sRGB in the bitmap and sRGB in every colour put into it. `setFillColor(red:
+/// green:blue:alpha:)` speaks DeviceRGB, which is a colour match on the way in,
+/// and #121212 would stop being #121212.
+func sRGB() -> CGColorSpace {
+    guard let space = CGColorSpace(name: CGColorSpace.sRGB) else { die("sRGB colour space unavailable") }
+    return space
+}
+
+func cgColor(_ rgb: RGB, alpha: CGFloat = 1) -> CGColor {
+    guard let color = CGColor(colorSpace: sRGB(), components: rgb.components(alpha)) else {
+        die("CGColor from sRGB components failed")
+    }
+    return color
+}
+
+func renderIcon(pixels: Int) -> CGImage {
+    guard
+        let ctx = CGContext(
+            data: nil, width: pixels, height: pixels,
+            bitsPerComponent: 8, bytesPerRow: 0, space: sRGB(),
+            bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue)
+    else { die("CGContext \(pixels)x\(pixels) failed") }
+
+    // Top-left origin, so the constants above read in the order the picture
+    // does. The scale stays ±1, which is what lets snap() round in user space.
+    ctx.translateBy(x: 0, y: CGFloat(pixels))
+    ctx.scaleBy(x: 1, y: -1)
+
+    // Round the MARGIN and derive the square from it. Rounding the square
+    // instead leaves an odd remainder to split, and at 16 pixels the artwork
+    // lands a pixel off centre. At 1024 this is Apple's 100/824/100 exactly.
+    let canvas = CGFloat(pixels)
+    let inset = (canvas * (1 - squareFraction) / 2).rounded()
+    let side = canvas - 2 * inset
+    let body = CGRect(x: inset, y: inset, width: side, height: side)
+    let corner = side * cornerFraction
+
+    ctx.saveGState()
+    ctx.addPath(CGPath(roundedRect: body, cornerWidth: corner, cornerHeight: corner, transform: nil))
+    ctx.clip()
+
+    // The only gradient in the icon, and it earns its place: a flat near-black
+    // square reads as a hole punched in the Dock rather than as an object.
+    let stops = bodyTop.components(1) + bodyBottom.components(1)
+    let locations: [CGFloat] = [0, 1]
+    guard
+        let gradient = CGGradient(
+            colorSpace: sRGB(), colorComponents: stops, locations: locations, count: 2)
+    else { die("CGGradient failed") }
+    ctx.drawLinearGradient(
+        gradient,
+        start: CGPoint(x: body.midX, y: body.minY),
+        end: CGPoint(x: body.midX, y: body.maxY),
+        options: [])
+
+    // Full bleed, and still inside the clip so its top corners round with the
+    // body. src/pardes.zig fills row 0 across the whole width the same way;
+    // that strip is the silhouette of an acme screen and it is the one thing
+    // that has to survive being two pixels tall.
+    ctx.setFillColor(cgColor(tagBar))
+    let tagRect = CGRect(
+        x: body.minX, y: body.minY,
+        width: side, height: max(1, (side * tagHeight).rounded()))
+    ctx.fill(tagRect)
+
+    // The block cursor at the end of it. Inside the clip and inset from the
+    // corner so the rounding never clips a corner off the block itself.
+    ctx.setFillColor(cgColor(cursor))
+    ctx.fill(
+        CGRect(
+            x: (body.maxX - side * (cursorRightPad + cursorWidth)).rounded(),
+            y: (tagRect.minY + tagRect.height * 0.24).rounded(),
+            width: max(1, (side * cursorWidth).rounded()),
+            height: max(1, (tagRect.height * 0.52).rounded())))
+    ctx.restoreGState()
+
+    // Glenda. One fill for the whole silhouette so the four ellipses union
+    // instead of seaming, then the eyes and the nose over the top of her.
+    let stage = CGRect(
+        x: body.minX + side * stageInset,
+        y: body.minY + side * stageTop,
+        width: side * (1 - 2 * stageInset),
+        height: side * (stageBottom - stageTop))
+
+    ctx.setFillColor(cgColor(text))
+    for blob in silhouette { ctx.addPath(blob.path(in: stage)) }
+    ctx.fillPath(using: .winding)
+
+    // The ground colour rather than black: her eyes and nose are HOLES in her,
+    // and a hole darker than what is behind it reads as paint. One fill for all
+    // three, so they can never disagree about which colour a hole is.
+    ctx.setFillColor(cgColor(bodyTop))
+    for hole in eyes + [nose] { ctx.addPath(hole.path(in: stage)) }
+    ctx.fillPath(using: .winding)
+
+    guard let image = ctx.makeImage() else { die("CGContext.makeImage failed at \(pixels)") }
+    return image
+}
+
+func writePNG(_ image: CGImage, to url: URL) {
+    guard
+        let sink = CGImageDestinationCreateWithURL(
+            url as CFURL, UTType.png.identifier as CFString, 1, nil)
+    else { die("cannot open \(url.path) for writing") }
+    CGImageDestinationAddImage(sink, image, nil)
+    guard CGImageDestinationFinalize(sink) else { die("encoding \(url.lastPathComponent) failed") }
+}
+
+// The ten names iconutil demands, spelled out rather than derived: the set is
+// fixed by the tool, and a loop that generated them would be a loop to read
+// before believing the list. 32, 256 and 512 appear twice under two names and
+// are simply drawn twice — a third of a megapixel, against the clarity of not
+// caching anything in a build tool.
+let variants: [(name: String, pixels: Int)] = [
+    ("icon_16x16.png", 16),
+    ("[email protected]", 32),
+    ("icon_32x32.png", 32),
+    ("[email protected]", 64),
+    ("icon_128x128.png", 128),
+    ("[email protected]", 256),
+    ("icon_256x256.png", 256),
+    ("[email protected]", 512),
+    ("icon_512x512.png", 512),
+    ("[email protected]", 1024),
+]
+
+let arguments = CommandLine.arguments
+guard arguments.count == 2 else {
+    die("usage: \(URL(fileURLWithPath: arguments.first ?? "icon").lastPathComponent) <output-directory>")
+}
+
+let files = FileManager.default
+let outputDir = URL(fileURLWithPath: arguments[1], isDirectory: true)
+let output = outputDir.appendingPathComponent("pardes.icns")
+
+// A fixed scratch path, cleared before use rather than a unique one: a run that
+// died half way leaves a partial iconset behind, and iconutil would happily
+// fold the stale sizes into the next icns without a word.
+let scratch = files.temporaryDirectory.appendingPathComponent("pardes-icon", isDirectory: true)
+let iconset = scratch.appendingPathComponent("pardes.iconset", isDirectory: true)
+
+try? files.removeItem(at: scratch)
+do {
+    try files.createDirectory(at: iconset, withIntermediateDirectories: true)
+    try files.createDirectory(at: outputDir, withIntermediateDirectories: true)
+} catch {
+    die("cannot create \(iconset.path): \(error.localizedDescription)")
+}
+
+for variant in variants {
+    writePNG(renderIcon(pixels: variant.pixels), to: iconset.appendingPathComponent(variant.name))
+}
+
+let iconutil = Process()
+iconutil.executableURL = URL(fileURLWithPath: "/usr/bin/iconutil")
+iconutil.arguments = ["-c", "icns", "-o", output.path, iconset.path]
+do {
+    try iconutil.run()
+} catch {
+    die("cannot run /usr/bin/iconutil: \(error.localizedDescription)")
+}
+iconutil.waitUntilExit()
+guard iconutil.terminationStatus == 0 else {
+    die("iconutil exited \(iconutil.terminationStatus) over \(iconset.path)")
+}
+
+try? files.removeItem(at: scratch)
diff --git a/src/macos/pardes.h b/src/macos/pardes.h
index e0d6fa32..1591130e 100644
--- a/src/macos/pardes.h
+++ b/src/macos/pardes.h
@@ -118,6 +118,15 @@ typedef enum {
   PARDES_MOUSE_DRAG = 3,
 } pardes_mouse_kind_e;
 
+// What the core just did, for a shell that can answer with something the hand
+// feels. Taken with pardes_take_haptic once per pump; the two acme verbs are
+// distinguished because they deserve distinct taps.
+typedef enum {
+  PARDES_HAPTIC_NONE = 0,
+  PARDES_HAPTIC_EXEC = 1,
+  PARDES_HAPTIC_LOOK = 2,
+} pardes_haptic_e;
+
 // ---------------------------------------------------------------- runtime
 
 // What the host lends the core. Two callbacks, because everything else the
@@ -149,8 +158,14 @@ int pardes_init(const pardes_runtime_s *runtime, uint16_t cols, uint16_t rows);
 void pardes_deinit(void);
 
 // Drain pty output into the core and perform the effects it queued. Call after
-// every input function and on every wakeup. Returns true if anything changed
-// and the host should mark its view dirty.
+// every input function and on every wakeup.
+//
+// The return value is whether this tick did any IO — bytes arrived from a pty,
+// or an effect was performed. It is NOT a repaint signal, and a host that uses
+// it as one shows a stale screen: moving the cursor, extending a selection,
+// changing mode and scrolling all mutate the grid while queueing nothing and
+// performing nothing, so they tick false. Mark the view dirty after any call
+// into the core and use this only to decide whether there was work.
 bool pardes_tick(void);
 
 // The core asked to exit (the Exit builtin, or the last pane closing).
@@ -159,6 +174,16 @@ bool pardes_should_quit(void);
 // A theme transition is mid-flight and wants ~60 Hz ticks until it settles.
 bool pardes_animating(void);
 
+// What to paint where the grid does not: the window background behind the
+// titlebar and behind a live resize the view has not caught up with. The
+// theme's own background, so it changes the instant the theme does — chrome
+// (taglines, the move box) fades instead, which is why this is not it.
+//
+// PARDES_COLOR_DEFAULT means the theme declares NO background of its own. A
+// terminal wears whatever it was already wearing; a window has nothing to
+// wear, so the host should go transparent and show its own backdrop.
+uint32_t pardes_theme_bg(void);
+
 // ---------------------------------------------------------------- events in
 
 // `cp` is a codepoint or one of PARDES_KEY_*; `text`/`len` are the host's
@@ -169,14 +194,41 @@ void pardes_paste(const char *text, size_t len);
 void pardes_mouse(pardes_mouse_button_e button, pardes_mouse_kind_e kind,
                   uint16_t col, uint16_t row, uint32_t mods);
 
-// Trackpad/precision wheel distance in rows, sign following the grid (positive
-// scrolls down). The core has no fractional scroll — it moves a row at a time —
-// so libpardes accumulates here and emits whole-row wheel presses, keeping the
-// remainder. Both other shells do this same accumulation host-side (stepScroll
-// in gui.zig, the drain loop in web/app.mjs); it lives in Zig here so the Swift
-// side stays a translator. A discrete wheel notch should go through
-// pardes_mouse instead.
-void pardes_scroll(float delta_rows, uint16_t col, uint16_t row);
+// Trackpad/precision wheel distance in CELLS, sign following the grid
+// (positive scrolls down and right). The core has no fractional scroll — it
+// moves a row or a column at a time — so libpardes accumulates here and emits
+// whole wheel presses, keeping the remainder. Both other shells do this same
+// accumulation host-side (stepScroll in gui.zig, the drain loop in
+// web/app.mjs); it lives in Zig here so the Swift side stays a translator, and
+// so the quantizer is unit-tested on a machine with no trackpad. A discrete
+// wheel notch should go through pardes_mouse instead.
+void pardes_scroll(float delta_rows, float delta_cols, uint16_t col,
+                   uint16_t row);
+
+// A two-finger trackpad rotation, in degrees since the last call, positive
+// counterclockwise (AppKit's sign, unchanged). The core has no rotation: this
+// is spent as the search-step keys, clockwise `n` and counterclockwise `N`, a
+// notch at a time with the remainder kept — the same accumulate-and-spend
+// shape as pardes_scroll, and in Zig for the same reason. Feed it the raw
+// per-event delta; pass 0 at gesture start to drop a stale remainder and to
+// stop a fling still coasting.
+void pardes_rotate(float degrees);
+
+// The fingers lifted. How fast they were moving decides everything: a slow
+// twist stops exactly where it was put, a flick keeps turning in proportion to
+// how hard it was thrown, and the two are the same curve — momentum ramps up
+// from zero rather than switching on at a threshold.
+//
+// A coast makes pardes_animating true and is spent by pardes_tick, so a host
+// that already re-pumps for theme transitions needs no new machinery; one that
+// never calls this simply has a dial with no momentum.
+void pardes_rotate_end(void);
+
+// Run one builtin command line, exactly as executing the same text in a tag
+// would. This is the core's own `command` event, which is how a nested pardes
+// talks to its host; here it is what a menu item is made of, and what opens
+// the file named on argv or dropped on the Dock icon (`Look <path>`).
+void pardes_command(const char *text, size_t len);
 
 // `cell_w`/`cell_h` are one cell in physical pixels, which only the native PDF
 // placement path reads. Pass the backing-store size, not points.
@@ -192,11 +244,85 @@ const pardes_cell_s *pardes_frame_cells(void);
 uint16_t pardes_frame_cols(void);
 uint16_t pardes_frame_rows(void);
 
+// One rasterized pixel attachment: a PDF page, or an image pane's pixels.
+//
+// Geometry is in PHYSICAL PIXELS, the space pardes_resize's cell_w/cell_h put
+// the core in. `cell_x`/`cell_y` are the pane body's origin in CELLS and the
+// only thing to multiply out; `dst_*` is relative to that origin and `src_*`
+// is the crop of the raster to take. Both are already clipped to the viewport,
+// so a continuous-scroll page needs no overflow clip of its own — but the body
+// (`cell_w` x `cell_h` cells) is still the rectangle nothing may paint past.
+//
+// `serial`, `page` and `revision` together are the cache key: a host holds its
+// decoded texture while all three hold still, and panning, fit and scrolling
+// deliberately do not move them.
+typedef struct {
+  uint32_t serial;
+  uint32_t page;
+  uint32_t revision;
+  uint16_t cell_x;
+  uint16_t cell_y;
+  uint16_t cell_w;
+  uint16_t cell_h;
+  uint32_t dst_x;
+  uint32_t dst_y;
+  uint32_t dst_w;
+  uint32_t dst_h;
+  uint32_t src_x;
+  uint32_t src_y;
+  uint32_t src_w;
+  uint32_t src_h;
+  // subpixel vertical displacement a proportional wheel kept
+  float offset_y;
+  uint32_t iw;
+  uint32_t ih;
+  // iw * ih * 4 bytes, RGBA8, borrowed until the next pardes_frame
+  const uint8_t *rgba;
+} pardes_image_s;
+
+// This frame's attachments, in paint order. Ask after pardes_frame; both are
+// valid until the next one, exactly like the cell buffer.
+uint32_t pardes_frame_images(void);
+const pardes_image_s *pardes_frame_image_list(void);
+
+// The file behind the FOCUSED pane, or NULL when there is none: a terminal, an
+// output buffer, or nothing focused. PDFs and images count — they are real
+// paths, and a titlebar proxy icon is about the file, not about who may edit
+// it. Borrowed until the next call, like pardes_font_take.
+const char *pardes_active_path(void);
+
+// ...and whether that pane holds edits which are not on disk. Always false for
+// anything with no buffer to save, PDFs and images included.
+bool pardes_active_dirty(void);
+
 // -1 when the cursor is hidden. `bar` asks for a thin insert-mode caret.
 int32_t pardes_cursor_x(void);
 int32_t pardes_cursor_y(void);
 bool pardes_cursor_bar(void);
 
+// The Look or Exec the core performed since this was last asked, and clears
+// it. Call it once per pump, after pardes_tick — the input functions run the
+// dispatch synchronously, so a gesture's pulse is already waiting by the time
+// its tick returns. PARDES_HAPTIC_NONE means nothing to feel.
+pardes_haptic_e pardes_take_haptic(void);
+
+// The font file the `Font` builtin asked for since this was last called, and
+// clears it; NULL when nothing was asked. Ask once per pump, beside the haptic
+// above. The string is a NUL-terminated absolute path owned by libpardes and
+// valid until the next call.
+//
+// A path rather than a family name: the core found the file by walking the
+// font directories itself, so both shells agree on which faces exist and
+// neither has to ask its platform to resolve a name it might resolve
+// differently. A `.ttc` collection names its first face, which is the cut the
+// file is named after.
+//
+// The host loads it, re-measures its cell, and reports the new grid through
+// pardes_resize. A file the host cannot load is one to ignore: keep wearing
+// the face that works, because a terminal that cannot draw has no way back
+// out of it.
+const char *pardes_font_take(void);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/main.zig b/src/main.zig
index 607b0136..4a067406 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -203,7 +203,9 @@ fn nativeMain(init: std.process.Init) !void {
     // Native shells opt into the user config; the sans-IO core and web keep
     // Options' null default. Read it before entering either frontend so every
     // builtin has run before that frontend can render its first frame.
-    opts.startup_config = @import("user_config.zig").load(init.io, arena, init.environ_map);
+    const found = @import("user_config.zig").load(init.io, arena, init.environ_map);
+    opts.startup_config = found.bytes;
+    opts.startup_config_path = found.path;
     switch (pardes.platform) {
         .tty => try @import("tty/tty.zig").run(init, opts),
         .gui => try @import("gui/gui.zig").run(init, opts),
@@ -233,13 +235,11 @@ fn parseCtrlKey(raw: []const u8) ?u21 {
 // so their inline tests need naming here to exist at all. gui.zig only
 // compiles when it IS the shell (it @cImports SDL), hence the comptime gate;
 // under -Dplatform=tty this block analyses to nothing. Naming a file gets THAT
-// file's tests and no further: fonts.zig is imported by both gui.zig and
-// builtins.zig and still needs its own line here.
+// file's tests and no further: fonts.zig is imported by gui.zig, builtins.zig
+// and the macOS host, and still needs its own line here.
 test {
     _ = @import("user_config.zig");
     _ = @import("allocators.zig");
-    if (comptime pardes.platform == .gui) {
-        _ = @import("gui/gui.zig");
-        _ = @import("gui/fonts.zig");
-    }
+    if (comptime pardes.platform == .gui) _ = @import("gui/gui.zig");
+    if (comptime pardes.font_picker) _ = @import("fonts.zig");
 }
diff --git a/src/nested.zig b/src/nested.zig
index 20c42dd0..16cea6a1 100644
--- a/src/nested.zig
+++ b/src/nested.zig
@@ -17,20 +17,69 @@
 //! socket sits at a path anyone can derive from a pid — `Exec …` arriving here
 //! is not something this protocol is allowed to say.
 //!
-//! Linux only. ponytail: darwin has no /proc, no SOCK_CLOEXEC and no accept4,
-//! and its `sockaddr.un.path` is 104 bytes rather than the 108 every buffer
-//! and unguarded memcpy below assumes. None of that is testable from here, so
-//! detection is simply off: a pardes inside a pardes on macOS opens a second
-//! session the way it always did.
+//! Linux and darwin. The two differ in every primitive this needs and in none
+//! of the design: /proc against libproc for the ancestor walk, SOCK_CLOEXEC
+//! and accept4 against a plain socket plus an fcntl, and a `sun_path` of 108
+//! bytes against one of 104 — which is why no buffer below spells a number,
+//! they are all sized from the field itself. Anywhere else the walk returns
+//! null and a pardes inside a pardes opens a second session, as before.
+//!
+//! macOS also has a third executable in the family: the app bundle. Its binary
+//! is the same build as `bin/pardes` installed a second time, at a path that
+//! shares nothing below the install prefix, so identity is compared at that
+//! prefix — see samePardesExecutable.
 const std = @import("std");
 const builtin = @import("builtin");
 const libc = std.c;
-const linux = std.os.linux; // statx; referenced only on linux
 
 // std.c has getenv but neither setter; the tests below need both
 extern "c" fn setenv(name: [*:0]const u8, value: [*:0]const u8, overwrite: c_int) c_int;
 extern "c" fn unsetenv(name: [*:0]const u8) c_int;
 
+const darwin = switch (builtin.os.tag) {
+    .macos, .ios, .tvos, .watchos, .visionos => true,
+    else => false,
+};
+
+/// This module is only as portable as its two ingredients: a way to name the
+/// executable and parent of an arbitrary pid, and unix sockets.
+const supported = builtin.os.tag == .linux or darwin;
+
+/// `sun_path` is 108 bytes on linux and 104 on darwin, and it is the hard
+/// limit on this whole feature: a path that does not fit is not a socket
+/// address, it is a truncated one pointing somewhere else. Taken from the
+/// struct so that the buffers, the fit checks and the memcpy below cannot
+/// disagree with the kernel or with each other.
+const sun_path_len = @typeInfo(@FieldType(libc.sockaddr.un, "path")).array.len;
+
+/// libproc, darwin's answer to /proc. `proc_pidpath` is readlink of
+/// `/proc/<pid>/exe`; `PROC_PIDTBSDINFO` carries the parent pid that linux
+/// spells `PPid:`. Both are same-uid readable, which is the only permission
+/// an ancestor walk through one's own processes needs.
+const PROC_PIDTBSDINFO: c_int = 3;
+const proc_bsdinfo = extern struct {
+    flags: u32,
+    status: u32,
+    xstatus: u32,
+    pid: u32,
+    ppid: u32,
+    /// uids, gids, comm, name, the tty and the start time: filled by the
+    /// kernel and unread here, but the call fails unless the buffer is the
+    /// whole 136-byte record.
+    rest: [116]u8,
+};
+extern "c" fn proc_pidpath(pid: c_int, buffer: *anyopaque, buffersize: u32) c_int;
+extern "c" fn proc_pidinfo(pid: c_int, flavor: c_int, arg: u64, buffer: *anyopaque, buffersize: c_int) c_int;
+
+/// Linux opens sockets CLOEXEC in one call; darwin has to set it afterwards.
+/// The gap is a race only against a fork on another thread, and both callers
+/// are past that: `listen` runs before the first pane exists, and `acceptLine`
+/// runs on a thread of its own long after spawning has settled.
+fn setCloexec(fd: c_int) void {
+    const FD_CLOEXEC: c_int = 1;
+    _ = libc.fcntl(fd, libc.F.SETFD, FD_CLOEXEC);
+}
+
 /// The longest command line this protocol carries or accepts. `Look ` plus a
 /// PATH_MAX path fits with room over; anything longer cannot have come from
 /// the client and is dropped rather than truncated into a different command.
@@ -41,7 +90,7 @@ pub const max_line = 4200;
 /// is per-user for the same reason a home directory is. Asked by the client
 /// (to derive the path), by the listener (to create and vet it) and by the
 /// sweeper (to scan it), so it is written once.
-fn socketDir(buf: *[108:0]u8) ?[:0]const u8 {
+fn socketDir(buf: *[sun_path_len:0]u8) ?[:0]const u8 {
     if (libc.getenv("XDG_RUNTIME_DIR")) |x|
         return std.fmt.bufPrintSentinel(buf, "{s}", .{std.mem.span(x)}, 0) catch null;
     const home = libc.getenv("HOME") orelse return null;
@@ -52,8 +101,8 @@ fn socketDir(buf: *[108:0]u8) ?[:0]const u8 {
 /// two pardes never collide and a nested child derives the exact path from the
 /// ancestor pid its tree walk found. The buffer is sun_path-sized: a longer
 /// path is not a socket address at all.
-pub fn socketPath(buf: *[108]u8, pid: libc.pid_t) ?[:0]const u8 {
-    var dir_buf: [108:0]u8 = undefined;
+pub fn socketPath(buf: *[sun_path_len]u8, pid: libc.pid_t) ?[:0]const u8 {
+    var dir_buf: [sun_path_len:0]u8 = undefined;
     const dir = socketDir(&dir_buf) orelse return null;
     // unsigned: {d} prints a leading '+' for a positive SIGNED int
     return std.fmt.bufPrintSentinel(buf, "{s}/pardes-{d}.sock", .{ dir, @as(u32, @intCast(pid)) }, 0) catch null;
@@ -66,34 +115,69 @@ fn stripDeleted(link: []const u8) []const u8 {
     return if (std.mem.endsWith(u8, link, suffix)) link[0 .. link.len - suffix.len] else link;
 }
 
-/// The tty and SDL builds are sibling frontends of the same program. Their
-/// installed names differ only by `-gui` (and, for cross builds, share the
-/// same `-os-arch` tail), so either one must recognise the other as an outer
-/// pardes. Requiring the same directory retains the executable-identity check:
-/// an unrelated ancestor merely named `pardes` is not enough.
+/// The install prefix a program directory belongs to. `bin/pardes` and
+/// `pardes.app/Contents/MacOS/pardes` are one build installed twice and share
+/// no directory at all, so comparing dirnames says they are strangers; both
+/// reduce to the prefix, and so does everything else — a directory that is
+/// neither wrapper is its own prefix, which leaves the same-directory rule
+/// below exactly as strict as it was.
+fn installPrefix(dir: []const u8) []const u8 {
+    const macos_dir = "/Contents/MacOS";
+    if (std.mem.endsWith(u8, dir, macos_dir)) {
+        const app = dir[0 .. dir.len - macos_dir.len];
+        if (std.mem.endsWith(u8, app, ".app")) return std.fs.path.dirname(app) orelse app;
+    }
+    const bin = "/bin";
+    if (std.mem.endsWith(u8, dir, bin)) return dir[0 .. dir.len - bin.len];
+    return dir;
+}
+
+/// The tty, SDL and macOS builds are sibling frontends of the same program.
+/// Their installed names differ only by `-gui` (and, for cross builds, share
+/// the same `-os-arch` tail), or not at all when one of them is the app bundle
+/// — so any of them must recognise any other as an outer pardes. Requiring the
+/// same install prefix retains the executable-identity check: an unrelated
+/// ancestor merely named `pardes` is not enough.
 fn samePardesExecutable(a_raw: []const u8, b_raw: []const u8) bool {
     const a = stripDeleted(a_raw);
     const b = stripDeleted(b_raw);
     if (std.mem.eql(u8, a, b)) return true;
-    const a_dir = std.fs.path.dirname(a) orelse return false;
-    const b_dir = std.fs.path.dirname(b) orelse return false;
+    const a_dir = installPrefix(std.fs.path.dirname(a) orelse return false);
+    const b_dir = installPrefix(std.fs.path.dirname(b) orelse return false);
     if (!std.mem.eql(u8, a_dir, b_dir)) return false;
 
-    const a_name = std.fs.path.basename(a);
-    const b_name = std.fs.path.basename(b);
-    const gui = "pardes-gui";
-    const tty = "pardes";
-    const a_gui = std.mem.startsWith(u8, a_name, gui);
-    const b_gui = std.mem.startsWith(u8, b_name, gui);
-    if (a_gui == b_gui) return false;
-    const gui_name = if (a_gui) a_name else b_name;
-    const tty_name = if (a_gui) b_name else a_name;
-    if (!std.mem.startsWith(u8, tty_name, tty)) return false;
-    const gui_tail = gui_name[gui.len..];
-    const tty_tail = tty_name[tty.len..];
-    if ((gui_tail.len != 0 and gui_tail[0] != '-') or
-        (tty_tail.len != 0 and tty_tail[0] != '-')) return false;
-    return std.mem.eql(u8, gui_tail, tty_tail);
+    return sameFamily(std.fs.path.basename(a), std.fs.path.basename(b));
+}
+
+/// What is left of a family name after the frontend part: `` for `pardes` and
+/// `pardes-gui`, `-linux-aarch64` for the cross-built spellings of both. Null
+/// when the name is not in the family at all — `not-pardes` and `pardesfoo`
+/// are other programs.
+fn familyTail(name: []const u8) ?[]const u8 {
+    const rest = if (std.mem.startsWith(u8, name, "pardes-gui"))
+        name["pardes-gui".len..]
+    else if (std.mem.startsWith(u8, name, "pardes"))
+        name["pardes".len..]
+    else
+        return null;
+    // `pardesfoo` shares a prefix and nothing else. A tail is a tail or empty.
+    if (rest.len != 0 and rest[0] != '-') return null;
+    return rest;
+}
+
+/// Two family names for the same build, given that they already share an
+/// install prefix. The tails have to agree — a linux binary and an x86_64 one
+/// in the same directory are two builds — unless one of them has no tail at
+/// all, which is the untagged name the default build and, unavoidably, the app
+/// bundle both produce: CFBundleExecutable is a fixed string, so the bundled
+/// copy of `pardes-macos-aarch64` is called `pardes` and nothing in the name
+/// records what it was. Loosening it that far is safe because the prefix
+/// already had to match, and a foreign-arch ancestor cannot be running here.
+fn sameFamily(a: []const u8, b: []const u8) bool {
+    if (std.mem.eql(u8, a, b)) return true;
+    const a_tail = familyTail(a) orelse return false;
+    const b_tail = familyTail(b) orelse return false;
+    return a_tail.len == 0 or b_tail.len == 0 or std.mem.eql(u8, a_tail, b_tail);
 }
 
 /// The `PPid:` field of a /proc/<pid>/status blob. Deliberately NOT field 4 of
@@ -120,34 +204,70 @@ fn sweepPid(name: []const u8) ?libc.pid_t {
     return std.fmt.parseInt(libc.pid_t, digits, 10) catch null;
 }
 
+/// Name the executable behind a pid, the way this OS spells it.
+fn exeOf(pid: libc.pid_t, buf: *[4096]u8) ?[]const u8 {
+    switch (builtin.os.tag) {
+        .linux => {
+            var name: [64:0]u8 = undefined;
+            const link = std.fmt.bufPrintSentinel(&name, "/proc/{d}/exe", .{@as(u32, @intCast(pid))}, 0) catch return null;
+            const n = libc.readlink(link, buf, buf.len);
+            if (n <= 0) return null;
+            return buf[0..@intCast(n)];
+        },
+        else => {
+            if (comptime !darwin) return null;
+            // Documented to want a PROC_PIDPATHINFO_MAXSIZE buffer, which is
+            // exactly this one, and to return the length it wrote.
+            const n = proc_pidpath(pid, buf, @intCast(buf.len));
+            if (n <= 0) return null;
+            return buf[0..@intCast(n)];
+        },
+    }
+}
+
+/// ...and its parent.
+fn parentOf(pid: libc.pid_t) ?libc.pid_t {
+    switch (builtin.os.tag) {
+        .linux => {
+            var name: [64:0]u8 = undefined;
+            var buf: [4096]u8 = undefined;
+            const status = std.fmt.bufPrintSentinel(&name, "/proc/{d}/status", .{@as(u32, @intCast(pid))}, 0) catch return null;
+            const fd = libc.open(status, .{ .ACCMODE = .RDONLY });
+            if (fd < 0) return null;
+            const got = libc.read(fd, &buf, buf.len);
+            _ = libc.close(fd);
+            if (got <= 0) return null;
+            return parsePPid(buf[0..@intCast(got)]);
+        },
+        else => {
+            if (comptime !darwin) return null;
+            var info: proc_bsdinfo = undefined;
+            const n = proc_pidinfo(pid, PROC_PIDTBSDINFO, 0, &info, @sizeOf(proc_bsdinfo));
+            // A short answer means the record this was compiled against is not
+            // the one the kernel filled, and `ppid` is then some other field.
+            if (n < @as(c_int, @sizeOf(proc_bsdinfo))) return null;
+            return @intCast(info.ppid);
+        },
+    }
+}
+
 /// The pid of the nearest ancestor running a pardes executable, or null.
-/// Identity is `readlink("/proc/<pid>/exe")` against our own; the tty `pardes`
-/// and SDL `pardes-gui` siblings also match when they live in the same
-/// directory. A name alone would call every unrelated `pardes` ancestor an
-/// outer instance. The hop cap is not for /proc, which cannot loop, but because
-/// the walk is driven by numbers read out of files and should not be able to
+/// Identity is that ancestor's executable path against our own; the tty, SDL
+/// and app-bundle siblings also match when they were installed together. A
+/// name alone would call every unrelated `pardes` ancestor an outer instance.
+/// The hop cap is not for the process tree, which cannot loop, but because the
+/// walk is driven by numbers read out of the kernel and should not be able to
 /// spin on a surprising one.
 pub fn outer() ?libc.pid_t {
-    if (comptime builtin.os.tag != .linux) return null;
+    if (comptime !supported) return null;
     var self_buf: [4096]u8 = undefined;
-    const self_n = libc.readlink("/proc/self/exe", &self_buf, self_buf.len);
-    if (self_n <= 0) return null;
-    const self_exe = stripDeleted(self_buf[0..@intCast(self_n)]);
+    const self_exe = exeOf(libc.getpid(), &self_buf) orelse return null;
     var pid = libc.getppid();
     var hops: usize = 0;
     while (pid > 1 and hops < 64) : (hops += 1) {
-        var name: [64:0]u8 = undefined;
         var buf: [4096]u8 = undefined;
-        const exe = std.fmt.bufPrintSentinel(&name, "/proc/{d}/exe", .{@as(u32, @intCast(pid))}, 0) catch return null;
-        const n = libc.readlink(exe, &buf, buf.len);
-        if (n > 0 and samePardesExecutable(buf[0..@intCast(n)], self_exe)) return pid;
-        const status = std.fmt.bufPrintSentinel(&name, "/proc/{d}/status", .{@as(u32, @intCast(pid))}, 0) catch return null;
-        const fd = libc.open(status, .{ .ACCMODE = .RDONLY });
-        if (fd < 0) return null;
-        const got = libc.read(fd, &buf, buf.len);
-        _ = libc.close(fd);
-        if (got <= 0) return null;
-        pid = parsePPid(buf[0..@intCast(got)]) orelse return null;
+        if (exeOf(pid, &buf)) |exe| if (samePardesExecutable(exe, self_exe)) return pid;
+        pid = parentOf(pid) orelse return null;
     }
     return null;
 }
@@ -159,7 +279,7 @@ pub fn outer() ?libc.pid_t {
 /// caller its own launch. Writes and returns: the answer is a pane appearing
 /// on someone else's screen, and there is nothing to wait for.
 pub fn sendLook(pid: libc.pid_t, path: []const u8, line: usize) bool {
-    if (comptime builtin.os.tag != .linux) return false;
+    if (comptime !supported) return false;
     // The protocol is one line, so a path with a line break IN it says
     // something else entirely: `we\nird.txt` arrived as `Look .../we` and the
     // outer instance opened a different file that happened to exist. \r goes
@@ -172,12 +292,15 @@ pub fn sendLook(pid: libc.pid_t, path: []const u8, line: usize) bool {
     else
         std.fmt.bufPrint(&cmd_buf, "Look {s}\n", .{path})) catch return false;
 
-    var path_buf: [108]u8 = undefined;
+    // sun_path-sized by construction, so `sock` cannot be longer than the
+    // field it is about to be copied into — socketPath returns null instead.
+    var path_buf: [sun_path_len]u8 = undefined;
     const sock = socketPath(&path_buf, pid) orelse return false;
     var addr: libc.sockaddr.un = .{ .path = @splat(0) };
     @memcpy(addr.path[0 .. sock.len + 1], sock[0 .. sock.len + 1]);
-    const fd = libc.socket(libc.AF.UNIX, libc.SOCK.STREAM | libc.SOCK.CLOEXEC, 0);
+    const fd = libc.socket(libc.AF.UNIX, libc.SOCK.STREAM, 0);
     if (fd < 0) return false;
+    setCloexec(fd);
     defer _ = libc.close(fd);
     if (libc.connect(fd, @ptrCast(&addr), @sizeOf(@TypeOf(addr))) != 0) return false;
     var off: usize = 0;
@@ -193,6 +316,27 @@ pub fn sendLook(pid: libc.pid_t, path: []const u8, line: usize) bool {
     return true;
 }
 
+/// The three things ensureSocketDir has to know about a path, from whichever
+/// call the platform actually offers. Darwin has fstatat and no statx; on
+/// linux std.c.fstatat is `void` — glibc hides it behind a versioned symbol
+/// std cannot name — so linux asks statx for the same three fields. Both
+/// spellings refuse to follow a symlink, which is the point of asking.
+const DirFacts = struct { mode: u32, uid: libc.uid_t };
+
+fn statNoFollow(path: [:0]const u8) ?DirFacts {
+    if (comptime darwin) {
+        var st: libc.Stat = undefined;
+        if (libc.fstatat(libc.AT.FDCWD, path, &st, libc.AT.SYMLINK_NOFOLLOW) != 0) return null;
+        return .{ .mode = st.mode, .uid = st.uid };
+    } else {
+        const linux = std.os.linux;
+        var stx: linux.Statx = undefined;
+        const want: linux.STATX = .{ .TYPE = true, .MODE = true, .UID = true };
+        if (libc.statx(linux.AT.FDCWD, path, linux.AT.SYMLINK_NOFOLLOW, want, &stx) != 0) return null;
+        return .{ .mode = stx.mode, .uid = stx.uid };
+    }
+}
+
 /// Create the socket directory if it is missing and refuse it unless it is a
 /// directory WE own with nothing granted to group or other. A planted path is
 /// the whole attack on a socket that runs commands, and $XDG_RUNTIME_DIR
@@ -202,7 +346,7 @@ fn ensureSocketDir(dir: [:0]const u8) bool {
     // without ~/.local/state would otherwise switch the feature off in
     // silence. Under $XDG_RUNTIME_DIR every prefix already exists and simply
     // EEXISTs, which is the ordinary case for the leaf too.
-    var partial: [108:0]u8 = undefined;
+    var partial: [sun_path_len:0]u8 = undefined;
     @memcpy(partial[0 .. dir.len + 1], dir[0 .. dir.len + 1]);
     for (1..dir.len) |i| {
         if (dir[i] != '/') continue;
@@ -211,13 +355,14 @@ fn ensureSocketDir(dir: [:0]const u8) bool {
         partial[i] = '/';
     }
     _ = libc.mkdir(dir, 0o700);
-    var stx: linux.Statx = undefined;
-    const want: linux.STATX = .{ .TYPE = true, .MODE = true, .UID = true };
-    // NOFOLLOW: a symlink where the directory should be is exactly the plant
-    if (libc.statx(linux.AT.FDCWD, dir, linux.AT.SYMLINK_NOFOLLOW, want, &stx) != 0) return false;
-    if (!linux.S.ISDIR(stx.mode)) return false;
-    if (stx.uid != libc.getuid()) return false;
-    return stx.mode & 0o077 == 0;
+    // A symlink where the directory should be is exactly the plant this
+    // guards against, so the stat above it does not follow one.
+    const st = statNoFollow(dir) orelse return false;
+    const IFMT: u32 = 0o170000;
+    const IFDIR: u32 = 0o040000;
+    if (st.mode & IFMT != IFDIR) return false;
+    if (st.uid != libc.getuid()) return false;
+    return st.mode & 0o077 == 0;
 }
 
 /// Unlink the socket files of pardes processes that are gone. A pardes killed
@@ -235,7 +380,7 @@ fn sweep(dir: [:0]const u8) void {
         // 0 = alive; EPERM = alive and someone else's. Only ESRCH is a corpse.
         const rc = libc.kill(pid, @enumFromInt(0));
         if (rc == 0 or libc.errno(rc) != .SRCH) continue;
-        var pbuf: [108]u8 = undefined;
+        var pbuf: [sun_path_len]u8 = undefined;
         _ = libc.unlink(socketPath(&pbuf, pid) orelse continue);
     }
 }
@@ -251,18 +396,20 @@ fn sweep(dir: [:0]const u8) void {
 /// holding this one would keep the socket bound long after we exit — the same
 /// shape as the inherited lock fd that once held a flock forever.
 pub fn listen() c_int {
-    if (comptime builtin.os.tag != .linux) return -1;
-    var dir_buf: [108:0]u8 = undefined;
+    if (comptime !supported) return -1;
+    var dir_buf: [sun_path_len:0]u8 = undefined;
     const dir = socketDir(&dir_buf) orelse return -1;
     if (!ensureSocketDir(dir)) return -1;
     sweep(dir);
-    var path_buf: [108]u8 = undefined;
+    // Fits by construction: socketPath writes into a sun_path-sized buffer and
+    // returns null rather than a truncated address.
+    var path_buf: [sun_path_len]u8 = undefined;
     const path = socketPath(&path_buf, libc.getpid()) orelse return -1;
     var addr: libc.sockaddr.un = .{ .path = @splat(0) };
-    if (path.len + 1 > addr.path.len) return -1;
     @memcpy(addr.path[0 .. path.len + 1], path[0 .. path.len + 1]);
-    const fd = libc.socket(libc.AF.UNIX, libc.SOCK.STREAM | libc.SOCK.CLOEXEC, 0);
+    const fd = libc.socket(libc.AF.UNIX, libc.SOCK.STREAM, 0);
     if (fd < 0) return -1;
+    setCloexec(fd);
     _ = libc.unlink(path); // pid reuse: a dead pardes' file would EADDRINUSE forever
     if (libc.bind(fd, @ptrCast(&addr), @sizeOf(@TypeOf(addr))) != 0) {
         _ = libc.close(fd);
@@ -281,11 +428,11 @@ pub fn listen() c_int {
 /// Close the listener and take its file away. Guarded on the fd rather than on
 /// the path, so a bind that FAILED cannot unlink a path this process never
 /// created; anything else is a no-op, which is what --nested and every
-/// non-linux build hand it.
+/// unsupported build hand it.
 pub fn unlisten(fd: c_int) void {
     if (fd < 0) return;
     _ = libc.close(fd);
-    var path_buf: [108]u8 = undefined;
+    var path_buf: [sun_path_len]u8 = undefined;
     if (socketPath(&path_buf, libc.getpid())) |path| _ = libc.unlink(path);
 }
 
@@ -297,9 +444,9 @@ pub fn unlisten(fd: c_int) void {
 /// nothing. Every accepted connection is CLOEXEC for the reason the listener
 /// is.
 pub fn acceptLine(fd: c_int, buf: []u8) ?[]const u8 {
-    if (comptime builtin.os.tag != .linux) return null;
+    if (comptime !supported) return null;
     while (true) {
-        const conn = libc.accept4(fd, null, null, libc.SOCK.CLOEXEC);
+        const conn = libc.accept(fd, null, null);
         if (conn < 0) {
             switch (libc.errno(conn)) {
                 .INTR => continue,
@@ -315,6 +462,7 @@ pub fn acceptLine(fd: c_int, buf: []u8) ?[]const u8 {
             }
         }
         defer _ = libc.close(conn);
+        setCloexec(conn);
         // A peer that connects and says nothing must not hold the listener:
         // this is a serial accept loop, and one silent connection used to
         // block every later launch until it let go. The client writes its one
@@ -342,7 +490,7 @@ pub fn acceptLine(fd: c_int, buf: []u8) ?[]const u8 {
 }
 
 test "socket path: XDG first, then a private dir under HOME, never /tmp" {
-    var buf: [108]u8 = undefined;
+    var buf: [sun_path_len]u8 = undefined;
     // The environment is process-wide and every test in this binary shares it.
     // The last case below reaches the "no directory at all" branch by blanking
     // both variables, and without this every later test ran without a HOME.
@@ -363,9 +511,11 @@ test "socket path: XDG first, then a private dir under HOME, never /tmp" {
     _ = unsetenv("XDG_RUNTIME_DIR");
     _ = setenv("HOME", "/home/who", 1);
     try std.testing.expectEqualStrings("/home/who/.local/state/pardes/pardes-4242.sock", socketPath(&buf, 4242).?);
-    // sun_path is 108 bytes including the NUL, so a directory that long has no
-    // socket address at all — say so instead of binding a truncated one
-    _ = setenv("XDG_RUNTIME_DIR", "/" ++ ("x" ** 100), 1);
+    // sun_path holds the NUL, so a directory that fills it has no socket
+    // address at all — say so instead of binding a truncated one. Sized from
+    // the field: the limit is 108 on linux and 104 on darwin, and a literal
+    // here would test nothing on whichever platform it was not written for.
+    _ = setenv("XDG_RUNTIME_DIR", "/" ++ ("x" ** (sun_path_len - 8)), 1);
     try std.testing.expect(socketPath(&buf, 4242) == null);
     _ = unsetenv("XDG_RUNTIME_DIR");
     _ = unsetenv("HOME");
@@ -407,6 +557,137 @@ test "tty and GUI sibling executables recognise each other" {
     ));
 }
 
+test "the app bundle is the same build as the binary installed beside it" {
+    // What `pardes foo.zig` typed into the bundle's own shell has to resolve:
+    // the ancestor is zig-out/pardes.app/..., this process is zig-out/bin/...,
+    // and nothing below zig-out is shared.
+    try std.testing.expect(samePardesExecutable(
+        "/work/zig-out/pardes.app/Contents/MacOS/pardes",
+        "/work/zig-out/bin/pardes",
+    ));
+    // ...and the SDL sibling, which reaches it by the name rule instead.
+    try std.testing.expect(samePardesExecutable(
+        "/work/zig-out/pardes.app/Contents/MacOS/pardes",
+        "/work/zig-out/bin/pardes-gui",
+    ));
+    // The case this machine actually produces: `zig build` installs the tty
+    // binary under its os-arch tail, and the bundle carries the same build
+    // under the one name CFBundleExecutable can spell.
+    try std.testing.expect(samePardesExecutable(
+        "/work/zig-out/pardes.app/Contents/MacOS/pardes",
+        "/work/zig-out/bin/pardes-macos-aarch64",
+    ));
+    // A different install is still a different program, however alike the
+    // paths look — this is the whole point of comparing anything at all.
+    try std.testing.expect(!samePardesExecutable(
+        "/work/zig-out/pardes.app/Contents/MacOS/pardes",
+        "/opt/zig-out/bin/pardes",
+    ));
+    // The wrapper is only transparent when it IS the wrapper: `Contents/MacOS`
+    // under something that is not a bundle keeps its own directory.
+    try std.testing.expect(!samePardesExecutable(
+        "/work/zig-out/pardes/Contents/MacOS/pardes",
+        "/work/zig-out/bin/pardes",
+    ));
+    // Nothing here may loosen the rule for two unrelated programs that merely
+    // sit in a bin and a bundle of the same tree.
+    try std.testing.expect(!samePardesExecutable(
+        "/work/zig-out/other.app/Contents/MacOS/other",
+        "/work/zig-out/bin/pardes",
+    ));
+}
+
+test "the ancestor walk reads this process's own parent" {
+    // The one thing a hand-written `struct proc_bsdinfo` gets wrong silently:
+    // a field ordering that puts something else where ppid should be still
+    // returns a plausible number. getppid knows the answer, so compare.
+    //
+    // Also the only check that libproc answers us at all — every caller of
+    // outer() treats a failure as "no outer instance", which is exactly what a
+    // permission problem would look like.
+    if (comptime !supported) return error.SkipZigTest;
+    try std.testing.expectEqual(libc.getppid(), parentOf(libc.getpid()).?);
+    // ...and that the walk terminates rather than spinning on pid 1's parent.
+    try std.testing.expect(parentOf(1) == null or parentOf(1).? <= 1);
+
+    var buf: [4096]u8 = undefined;
+    const exe = exeOf(libc.getpid(), &buf).?;
+    try std.testing.expect(exe.len > 0);
+    try std.testing.expect(exe[0] == '/');
+    // The test binary is not a pardes, so the walk must come back empty rather
+    // than matching some ancestor by accident.
+    try std.testing.expect(outer() == null);
+}
+
+extern "c" fn mkdtemp(template: [*:0]u8) ?[*:0]u8;
+extern "c" fn rmdir(path: [*:0]const u8) c_int;
+
+test "a Look line survives the socket round trip" {
+    // Everything the protocol actually does, against a real kernel: bind,
+    // chmod, connect, write, accept, read, and the one-verb filter. The pure
+    // functions above cannot see any of it, and every primitive here is
+    // spelled differently on the two platforms this now supports.
+    if (comptime !supported) return error.SkipZigTest;
+
+    // A private directory of our own. Not the developer's real state dir: this
+    // binds a socket named after a pid that is the TEST's, and sweep() unlinks
+    // what it finds beside it.
+    var tmpl: [64:0]u8 = undefined;
+    _ = std.fmt.bufPrintSentinel(&tmpl, "/tmp/pardes-nested-XXXXXX", .{}, 0) catch unreachable;
+    if (mkdtemp(&tmpl) == null) return error.SkipZigTest;
+    const dir = std.mem.sliceTo(&tmpl, 0);
+    defer _ = rmdir(tmpl[0..dir.len :0]);
+
+    var xdg_buf: [4096:0]u8 = undefined;
+    const xdg0 = if (libc.getenv("XDG_RUNTIME_DIR")) |v| std.fmt.bufPrintSentinel(&xdg_buf, "{s}", .{std.mem.span(v)}, 0) catch null else null;
+    defer {
+        if (xdg0) |v| {
+            _ = setenv("XDG_RUNTIME_DIR", v, 1);
+        } else _ = unsetenv("XDG_RUNTIME_DIR");
+    }
+    _ = setenv("XDG_RUNTIME_DIR", tmpl[0..dir.len :0], 1);
+
+    const fd = listen();
+    try std.testing.expect(fd >= 0);
+    defer unlisten(fd);
+
+    // Sent to our own pid, which is the pid listen() named the socket after.
+    // The client closes as it returns, and the line is already queued, so the
+    // single-threaded accept below finds a complete connection waiting — no
+    // thread and no timeout needed to prove the protocol.
+    try std.testing.expect(sendLook(libc.getpid(), "/etc/hosts", 42));
+    var buf: [max_line]u8 = undefined;
+    try std.testing.expectEqualStrings("Look /etc/hosts:42", acceptLine(fd, &buf).?);
+
+    // ...and without a line number, which is the directory and image case.
+    try std.testing.expect(sendLook(libc.getpid(), "/etc", 0));
+    try std.testing.expectEqualStrings("Look /etc", acceptLine(fd, &buf).?);
+
+    // The socket takes one verb. Anything else is dropped rather than run, so
+    // the next Look is what comes back — proving the filter skipped it without
+    // dropping the connection after it.
+    try std.testing.expect(writeLine(libc.getpid(), "Exec rm -rf /\n"));
+    try std.testing.expect(sendLook(libc.getpid(), "/etc/passwd", 0));
+    try std.testing.expectEqualStrings("Look /etc/passwd", acceptLine(fd, &buf).?);
+
+    // A path that cannot be one line is not escaped, it is refused.
+    try std.testing.expect(!sendLook(libc.getpid(), "/etc/ho\nsts", 0));
+}
+
+/// sendLook with the framing bypassed, so a test can put something on the wire
+/// that the client would never send.
+fn writeLine(pid: libc.pid_t, line: []const u8) bool {
+    var path_buf: [sun_path_len]u8 = undefined;
+    const sock = socketPath(&path_buf, pid) orelse return false;
+    var addr: libc.sockaddr.un = .{ .path = @splat(0) };
+    @memcpy(addr.path[0 .. sock.len + 1], sock[0 .. sock.len + 1]);
+    const fd = libc.socket(libc.AF.UNIX, libc.SOCK.STREAM, 0);
+    if (fd < 0) return false;
+    defer _ = libc.close(fd);
+    if (libc.connect(fd, @ptrCast(&addr), @sizeOf(@TypeOf(addr))) != 0) return false;
+    return libc.write(fd, line.ptr, line.len) == @as(isize, @intCast(line.len));
+}
+
 test "the sweep only recognises its own socket names" {
     try std.testing.expectEqual(@as(libc.pid_t, 7), sweepPid("pardes-7.sock").?);
     try std.testing.expectEqual(@as(libc.pid_t, 4194304), sweepPid("pardes-4194304.sock").?);
diff --git a/src/output_pane.zig b/src/output_pane.zig
index 8c93709c..8ff98845 100644
--- a/src/output_pane.zig
+++ b/src/output_pane.zig
@@ -27,7 +27,7 @@ const config = @import("config.zig");
 const lsp = @import("lsp/lsp.zig");
 /// the installed fonts, for openFonts. GUI only, behind the same comptime
 /// branch builtins.zig imports it through — see the note there.
-const fonts = if (pardes.platform == .gui) @import("gui/fonts.zig") else struct {};
+const fonts = if (pardes.font_picker) @import("fonts.zig") else struct {};
 
 /// What opened this buffer — THE field, and the only input to `traits`.
 ///
@@ -385,12 +385,13 @@ pub fn openThemes(p: *Pardes, id: usize) !void {
 /// stopping picks one. Everything that makes that work is already above; this
 /// is the same eight lines pointed at a different list.
 ///
-/// GUI only, and the body says so rather than the signature: fonts.list and
-/// the FontSel origin both exist only there, and a comptime-false `if` is what
-/// keeps the tty build from analysing either. The dead parameters on that
-/// build are the honest shape of "this platform cannot open one".
+/// Only where the shell draws its own text, and the body says so rather than
+/// the signature: fonts.list and the FontSel origin both exist only there, and
+/// a comptime-false `if` is what keeps the tty build from analysing either.
+/// The dead parameters on that build are the honest shape of "this platform
+/// cannot open one".
 pub fn openFonts(p: *Pardes, id: usize) !void {
-    if (pardes.platform == .gui) {
+    if (pardes.font_picker) {
         const arena = p.scratch.allocator();
         const font_list = fonts.list(arena, null);
         var len: usize = 0;
@@ -437,7 +438,6 @@ fn openStepped(p: *Pardes, id: usize, from: Origin, text: []const u8) !void {
 /// case. A second builtin would have been a second renderer over a superset of
 /// these rows, and the two would have drifted the first time a column moved.
 pub fn openHelp(p: *Pardes, id: usize, prefix: []const u8) !void {
-    const pane = p.panes[id] orelse return error.MissingPane;
     const full_header = "pardes builtins, and how to run each:\nSPC and its keys, a chord, a button, the\ntopbar - or the name, executed anywhere.\n\n";
     const group_header = "pardes builtins under SPC";
     var len: usize = if (prefix.len == 0)
@@ -451,7 +451,6 @@ pub fn openHelp(p: *Pardes, id: usize, prefix: []const u8) !void {
         len += row.line.len + 1;
     }
     const content = try p.gpa.alloc(u8, len);
-    errdefer p.gpa.free(content);
     var at: usize = 0;
     if (prefix.len == 0) {
         @memcpy(content[0..full_header.len], full_header);
@@ -476,15 +475,51 @@ pub fn openHelp(p: *Pardes, id: usize, prefix: []const u8) !void {
         at += 1;
     }
     std.debug.assert(at == content.len);
-    // the buffer says what made it, so finding the open one is asking that and
-    // not matching its name
+    // content is handed off unfreed on purpose: openRead adopts it or frees
+    // it, and nothing between the alloc above and this line can fail.
+    return openRead(p, id, .{ .cmd = .Help }, prefix, content);
+}
+
+/// The Config builtin: WHERE the startup config file is, as one line of text.
+///
+/// The PATH and not the file. `Look` on the line opens it when it exists, and
+/// when it does not the path is still the entire answer — "put your Theme and
+/// Font lines HERE" is the question this is asked, and a builtin that opened
+/// an empty buffer instead would have said nothing. The core never resolved
+/// it: the launcher did, before init (Options.startup_config_path), so this
+/// prints what was actually consulted rather than recomputing a guess that
+/// could differ from it.
+pub fn openConfig(p: *Pardes, id: usize) !void {
+    const content = if (p.opts.startup_config_path) |path|
+        try std.fmt.allocPrint(p.gpa, "{s}\n", .{path})
+    else
+        // the browser, and a native launch with no HOME to build one from
+        try p.gpa.dupe(u8, "no per-user config path\n");
+    return openRead(p, id, .{ .cmd = .Config }, "", content);
+}
+
+/// Open a buffer you READ, and go there: the shared tail of every builtin
+/// whose answer is a document rather than a list. Asking again REFRESHES the
+/// one already open instead of stacking a twin beside it — found by its
+/// ORIGIN, never by matching its name, for the reason the whole file exists.
+///
+/// The mirror of `openStepped`, and the difference is the two lines at the
+/// ends: focus comes HERE (you asked to read it) where a results buffer
+/// leaves you in the pane that asked, and n/N are not armed, because prose
+/// has nowhere to step to.
+///
+/// `content` is gpa-owned: adopted by the buffer, or freed here when there is
+/// nowhere to put it.
+fn openRead(p: *Pardes, id: usize, from: Origin, arg: []const u8, content: []u8) !void {
+    errdefer p.gpa.free(content);
+    const pane = p.panes[id] orelse return error.MissingPane;
     for (p.panes, 0..) |slot, i| {
         const hp = slot orelse continue;
         const hf = if (hp.file) |*f| f else continue;
         const ho = if (hf.output) |*o| o else continue;
-        if (!std.meta.eql(ho.from, Origin{ .cmd = .Help })) continue;
+        if (!std.meta.eql(ho.from, from)) continue;
         file_pane.setContent(p, hf, content);
-        setArg(ho, prefix);
+        setArg(ho, arg);
         hf.scroll = 0;
         hp.cur_row = 0;
         hp.msel.active = false;
@@ -493,7 +528,7 @@ pub fn openHelp(p: *Pardes, id: usize, prefix: []const u8) !void {
     }
     const dir = if (pane.file) |f| (std.fs.path.dirname(f.path) orelse "/") else pane.cwdSlice();
     const free = p.freeSlot() orelse return error.NoPaneSlots;
-    const np = try open(p, free, dir, .{ .cmd = .Help }, prefix, content);
+    const np = try open(p, free, dir, from, arg, content);
     p.placeDoc(id, free, np);
     p.active = free;
 }
diff --git a/src/pardes.zig b/src/pardes.zig
index e2ad426f..e9cc746d 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -45,6 +45,12 @@ pub const lsp = @import("lsp/lsp.zig");
 pub const Platform = enum { tty, gui, web, macos };
 pub const platform: Platform = @field(Platform, @tagName(@import("pardes_config").platform));
 
+/// Frontends that draw their own text, and can therefore be told which face to
+/// wear. On the tty the font belongs to the terminal emulator and in the
+/// browser it belongs to the page, so there the Font builtins are not
+/// disabled so much as meaningless — see builtins.zig.
+pub const font_picker = platform == .gui or platform == .macos;
+
 /// Native PDF quality is a shell property, but the core owns MuPDF and the
 /// RGBA cache. Kitty favors wire bandwidth; SDL favors physical-pixel text
 /// quality and asks the renderer to cover either fit axis without upscaling.
@@ -1742,6 +1748,43 @@ test "startup config runs builtin lines in order and isolates bad lines" {
     };
 }
 
+test "Config prints the resolved startup config path and refreshes one buffer" {
+    const path = "/home/pardes-test/.config/pardes";
+    // `startup_config` stays null: the file is MISSING and the path still
+    // resolves, which is the case this builtin exists to answer.
+    const p = try Pardes.init(std.testing.allocator, .{ .startup_config_path = path });
+    defer p.deinit();
+
+    try std.testing.expect(p.executeBuiltinLine(0, "Config"));
+    const opened = p.active;
+    const out = p.panes[opened].?.file.?;
+    try std.testing.expectEqualStrings(path ++ "\n", out.content);
+    try std.testing.expectEqualStrings(config.config_buffer, std.fs.path.basename(out.path));
+    try std.testing.expectEqual(output_pane.Origin{ .cmd = .Config }, out.output.?.from);
+
+    // Asking again refreshes the buffer already open rather than stacking a
+    // byte-identical twin beside it — Help's rule, and for the same reason.
+    try std.testing.expect(p.executeBuiltinLine(0, "Config"));
+    try std.testing.expectEqual(opened, p.active);
+    var buffers: usize = 0;
+    for (p.panes) |slot| {
+        const sp = slot orelse continue;
+        const f = sp.file orelse continue;
+        const o = f.output orelse continue;
+        if (std.meta.eql(o.from, output_pane.Origin{ .cmd = .Config })) buffers += 1;
+    }
+    try std.testing.expectEqual(@as(usize, 1), buffers);
+}
+
+test "Config says so when there is no per-user config path" {
+    const p = try Pardes.init(std.testing.allocator, .{});
+    defer p.deinit();
+
+    try std.testing.expect(p.executeBuiltinLine(0, "Config"));
+    const out = p.panes[p.active].?.file.?;
+    try std.testing.expect(std.mem.indexOf(u8, out.content, "no per-user config path") != null);
+}
+
 test "runtime theme changes animate chrome and retarget without a jump" {
     const p = try Pardes.init(std.testing.allocator, .{ .tty_only = true });
     defer p.deinit();
@@ -3230,6 +3273,22 @@ pub const File = struct {
     /// goes through file_pane.setContent, which bumps this; a pipe completion
     /// accepted against another revision would overwrite intervening work.
     revision: u32 = 0,
+    /// The `revision` this buffer was last WRITTEN at. Equal means what is on
+    /// screen is what is on disk; anything else is unsaved work.
+    ///
+    /// Bookkeeping only — nothing in the core renders it, and no shell has to
+    /// read it. It exists because a windowed host has somewhere to PUT the
+    /// answer (macOS puts a dot in the close button, and the proxy icon it sits
+    /// beside is the same pane's path), and a shell cannot derive it: revision
+    /// counts edits, and only the save knows which edit was the last one
+    /// committed. Zero for a fresh buffer, which is why every construction site
+    /// gets clean-on-open from the default and none of them mention it.
+    ///
+    /// Marked at the moment Save is ASKED, not when the write lands: the
+    /// save_file effect carries no completion back, so this is as honest as the
+    /// rest of that path. A failed write reads as saved, exactly as the tagline
+    /// already does.
+    saved_revision: u32 = 0,
     /// set = this is an OUTPUT buffer (acme's +Errors): a file pane with no
     /// file behind it, showing text the core produced itself. It records the
     /// COMMAND that opened it, and output_pane.zig's one table turns that into
@@ -4191,6 +4250,11 @@ pub const Options = struct {
     /// deterministic; when present, each line is dispatched as a builtin
     /// before init returns and therefore before any frontend can render.
     startup_config: ?[]const u8 = null,
+    /// ...and WHERE that came from, which is a separate fact: the path
+    /// resolves even when the file does not exist, and that is precisely the
+    /// case the Config builtin is asked about. Null on the web and in every
+    /// core test, where there is no per-user config to name.
+    startup_config_path: ?[]const u8 = null,
     image_allocator: ?std.mem.Allocator = null,
     pdf_allocator: ?std.mem.Allocator = null,
     tree_sitter_allocator: ?std.mem.Allocator = null,
@@ -4234,6 +4298,18 @@ const PendingPipe = struct {
     }
 };
 
+/// The acme verb the core just performed, for a shell that can answer with
+/// something physical. macOS taps the trackpad under the finger that asked
+/// (NSHapticFeedbackManager); the SDL shell already does the same thing with a
+/// gamepad — `rumble` in src/gui/deck.zig, "a brief gentle ack for
+/// execute/look, not a buzz". Two verbs rather than one flag because they
+/// deserve to feel different: Exec did something, Look went somewhere.
+pub const Haptic = enum { none, exec, look };
+
+/// Zero-sized off macOS, the way PdfSlot is off -Dmupdf: no other shell reads
+/// the field, so no other shell carries it.
+const HapticSlot = if (platform == .macos) Haptic else void;
+
 pub const Pardes = struct {
     gpa: std.mem.Allocator,
     image_gpa: std.mem.Allocator,
@@ -4308,6 +4384,10 @@ pub const Pardes = struct {
     /// the PETSCII matcher without it.
     native_images: bool = false,
     quit: bool = false,
+    /// The Look or Exec that has happened and not yet been felt, taken by the
+    /// shell once per pump (takeHaptic). A pulse, not a queue: five Execs
+    /// inside one keystroke are still one thing the hand did.
+    haptic: HapticSlot = if (platform == .macos) .none else {},
     drag: Drag = .none,
     hover_col: u16 = 0,
     hover_row: u16 = 0,
@@ -4466,6 +4546,9 @@ pub const Pardes = struct {
         p.applyStartupConfig();
         p.finishThemeInitialization();
         p.sync();
+        // A config file that opens a file with `Look …` armed the pulse before
+        // anyone touched anything. Nobody asked for that, so boot is silent.
+        _ = p.takeHaptic();
         return p;
     }
 
@@ -11641,6 +11724,7 @@ pub const Pardes = struct {
     /// search of the pane it came from, which is acme's button-3.
     pub fn lookAt(p: *Pardes, id: usize, txt: []const u8) void {
         const pane = p.panes[id] orelse return;
+        p.noteHaptic(.look);
         const trimmed = std.mem.trim(u8, txt, " \t\r\n");
         // `` @`ls -la` `` names a COMMAND, not a path: run it, and land in the
         // pane that answers — looking at a thing means being SHOWN it, and a
@@ -11808,6 +11892,10 @@ pub const Pardes = struct {
         const pane = p.panes[id] orelse return null;
         const cmd = commandText(txt);
         if (cmd.len == 0) return null;
+        // Before the builtin dispatch, and only at depth zero: `Exec ls` comes
+        // back through here as `ls` (executeBuiltinLine holds the depth), and
+        // one Tab is one thing the hand did, however many words it unwraps to.
+        if (p.exec_depth == 0) p.noteHaptic(.exec);
         if (p.executeBuiltinLine(id, cmd)) return null;
         if (p.exec_depth >= max_exec_depth) return null;
         p.exec_depth += 1;
@@ -12282,6 +12370,7 @@ pub const Pardes = struct {
         p.applyStartupConfig();
         p.finishThemeInitialization();
         p.sync();
+        _ = p.takeHaptic(); // see init: a restored session is not a gesture
         return p;
     }
 
@@ -12549,6 +12638,23 @@ pub const Pardes = struct {
         return p.chrome_animation.isActive();
     }
 
+    /// Arm the pulse. Look wins a tie because a Look that runs a command
+    /// (`` @`ls` ``, which is one gesture spelled as both) is felt as the
+    /// thing the user asked for, not as the shell it happened to need.
+    fn noteHaptic(p: *Pardes, pulse: Haptic) void {
+        if (comptime platform != .macos) return;
+        if (p.haptic == .look) return;
+        p.haptic = pulse;
+    }
+
+    /// Take the armed pulse and disarm. The shell calls this once per pump,
+    /// after the tick that may have set it.
+    pub fn takeHaptic(p: *Pardes) Haptic {
+        if (comptime platform != .macos) return .none;
+        defer p.haptic = .none;
+        return p.haptic;
+    }
+
     fn finishThemeInitialization(p: *Pardes) void {
         p.chrome_animation.snap(ChromeTheme.fromTheme(p.theme()));
         p.animate_theme_changes = true;
diff --git a/src/user_config.zig b/src/user_config.zig
index 455e8a3c..389188c1 100644
--- a/src/user_config.zig
+++ b/src/user_config.zig
@@ -31,17 +31,26 @@ pub fn path(gpa: std.mem.Allocator, env: *const std.process.Environ.Map) !?[]u8
     return try std.fs.path.join(gpa, &.{ home, ".config", "pardes" });
 }
 
-/// Missing, unreadable, oversized, or otherwise unusable config is simply no
-/// config. The arena passed by main owns successful bytes for the process.
+/// The config file: WHERE it was looked for, and what was there. Missing,
+/// unreadable, oversized, or otherwise unusable config is simply no config —
+/// but the path resolves either way, because "nothing is there yet" is the
+/// answer the Config builtin exists to give and a null would erase it. The
+/// arena passed by the launcher owns both for the process.
+pub const Found = struct {
+    path: ?[]const u8 = null,
+    bytes: ?[]const u8 = null,
+};
+
 pub fn load(
     io: std.Io,
     gpa: std.mem.Allocator,
     env: *const std.process.Environ.Map,
-) ?[]u8 {
-    const config_path = path(gpa, env) catch return null;
-    defer if (config_path) |p| gpa.free(p);
-    const p = config_path orelse return null;
-    return std.Io.Dir.cwd().readFileAlloc(io, p, gpa, .limited(max_bytes)) catch null;
+) Found {
+    const config_path = (path(gpa, env) catch return .{}) orelse return .{};
+    return .{
+        .path = config_path,
+        .bytes = std.Io.Dir.cwd().readFileAlloc(io, config_path, gpa, .limited(max_bytes)) catch null,
+    };
 }
 
 fn nonEmpty(value: ?[]const u8) ?[]const u8 {
@@ -88,10 +97,16 @@ test "config loader is silent when missing and returns exact file bytes" {
     defer env.deinit();
     try env.put("XDG_CONFIG_HOME", base_buf[0..base_len]);
 
-    try std.testing.expect(load(std.testing.io, std.testing.allocator, &env) == null);
+    const missing = load(std.testing.io, std.testing.allocator, &env);
+    defer std.testing.allocator.free(missing.path.?);
+    const expected = try std.fs.path.join(std.testing.allocator, &.{ base_buf[0..base_len], "pardes" });
+    defer std.testing.allocator.free(expected);
+    try std.testing.expectEqualStrings(expected, missing.path.?);
+    try std.testing.expect(missing.bytes == null);
     const source = "Theme dark\nUnknown command\nTheme acme\n";
     try tmp.dir.writeFile(std.testing.io, .{ .sub_path = "pardes", .data = source });
-    const bytes = load(std.testing.io, std.testing.allocator, &env).?;
-    defer std.testing.allocator.free(bytes);
-    try std.testing.expectEqualStrings(source, bytes);
+    const found = load(std.testing.io, std.testing.allocator, &env);
+    defer std.testing.allocator.free(found.path.?);
+    defer std.testing.allocator.free(found.bytes.?);
+    try std.testing.expectEqualStrings(source, found.bytes.?);
 }