diff --git a/src/font/Atlas.zig b/src/font/Atlas.zig
index 01ee5caa6..fcdf6ec53 100644
--- a/src/font/Atlas.zig
+++ b/src/font/Atlas.zig
@@ -38,18 +38,16 @@ nodes: std.ArrayListUnmanaged(Node) = .{},
 /// different formats, you must use multiple atlases or convert the textures.
 format: Format = .greyscale,
 
-/// This will be set to true when the atlas has data set on it. It is up
-/// to the user of the atlas to set this to false when they observe the value.
-/// This is a useful value to know if you need to send new data to the GPU or
-/// not.
-modified: bool = false,
+/// This will be incremented every time the atlas is modified. This is useful
+/// for knowing if the texture data has changed since the last time it was
+/// sent to the GPU. It is up the user of the atlas to read this value atomically
+/// to observe it.
+modified: std.atomic.Value(usize) = .{ .raw = 0 },
 
-/// This will be set to true when the atlas has been resized. It is up
-/// to the user of the atlas to set this to false when they observe the value.
-/// The resized value is useful for sending textures to the GPU to know if
-/// a new texture needs to be allocated or if an existing one can be
-/// updated in-place.
-resized: bool = false,
+/// This will be incremented every time the atlas is resized. This is useful
+/// for knowing if a GPU texture can be updated in-place or if it requires
+/// a resize operation.
+resized: std.atomic.Value(usize) = .{ .raw = 0 },
 
 pub const Format = enum(u8) {
     greyscale = 0,
@@ -99,7 +97,6 @@ pub fn init(alloc: Allocator, size: u32, format: Format) !Atlas {
 
     // This sets up our initial state
     result.clear();
-    result.modified = false;
 
     return result;
 }
@@ -243,7 +240,7 @@ pub fn set(self: *Atlas, reg: Region, data: []const u8) void {
         );
     }
 
-    self.modified = true;
+    _ = self.modified.fetchAdd(1, .monotonic);
 }
 
 // Grow the texture to the new size, preserving all previously written data.
@@ -284,13 +281,13 @@ pub fn grow(self: *Atlas, alloc: Allocator, size_new: u32) Allocator.Error!void
     }, data_old[size_old * self.format.depth() ..]);
 
     // We are both modified and resized
-    self.modified = true;
-    self.resized = true;
+    _ = self.modified.fetchAdd(1, .monotonic);
+    _ = self.resized.fetchAdd(1, .monotonic);
 }
 
 // Empty the atlas. This doesn't reclaim any previously allocated memory.
 pub fn clear(self: *Atlas) void {
-    self.modified = true;
+    _ = self.modified.fetchAdd(1, .monotonic);
     @memset(self.data, 0);
     self.nodes.clearRetainingCapacity();
 
@@ -475,8 +472,9 @@ test "exact fit" {
     var atlas = try init(alloc, 34, .greyscale); // +2 for 1px border
     defer atlas.deinit(alloc);
 
+    const modified = atlas.modified.load(.monotonic);
     _ = try atlas.reserve(alloc, 32, 32);
-    try testing.expect(!atlas.modified);
+    try testing.expectEqual(modified, atlas.modified.load(.monotonic));
     try testing.expectError(Error.AtlasFull, atlas.reserve(alloc, 1, 1));
 }
 
@@ -505,9 +503,10 @@ test "writing data" {
     defer atlas.deinit(alloc);
 
     const reg = try atlas.reserve(alloc, 2, 2);
-    try testing.expect(!atlas.modified);
+    const old = atlas.modified.load(.monotonic);
     atlas.set(reg, &[_]u8{ 1, 2, 3, 4 });
-    try testing.expect(atlas.modified);
+    const new = atlas.modified.load(.monotonic);
+    try testing.expect(new > old);
 
     // 33 because of the 1px border and so on
     try testing.expectEqual(@as(u8, 1), atlas.data[33]);
@@ -531,14 +530,14 @@ test "grow" {
     try testing.expectEqual(@as(u8, 3), atlas.data[9]);
     try testing.expectEqual(@as(u8, 4), atlas.data[10]);
 
-    // Reset our state
-    atlas.modified = false;
-    atlas.resized = false;
-
     // Expand by exactly 1 should fit our new 1x1 block.
+    const old_modified = atlas.modified.load(.monotonic);
+    const old_resized = atlas.resized.load(.monotonic);
     try atlas.grow(alloc, atlas.size + 1);
-    try testing.expect(atlas.modified);
-    try testing.expect(atlas.resized);
+    const new_modified = atlas.modified.load(.monotonic);
+    const new_resized = atlas.resized.load(.monotonic);
+    try testing.expect(new_modified > old_modified);
+    try testing.expect(new_resized > old_resized);
     _ = try atlas.reserve(alloc, 1, 1);
 
     // Ensure our data is still set. Not the offsets change due to size.
diff --git a/src/font/shaper/coretext.zig b/src/font/shaper/coretext.zig
index 2ea316637..3aaaef5d3 100644
--- a/src/font/shaper/coretext.zig
+++ b/src/font/shaper/coretext.zig
@@ -5,6 +5,7 @@ const macos = @import("macos");
 const trace = @import("tracy").trace;
 const font = @import("../main.zig");
 const Face = font.Face;
+const Collection = font.Collection;
 const DeferredFace = font.DeferredFace;
 const Group = font.Group;
 const GroupCache = font.GroupCache;
@@ -397,7 +398,7 @@ test "run iterator" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -416,7 +417,7 @@ test "run iterator" {
 
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -436,7 +437,7 @@ test "run iterator" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -483,7 +484,7 @@ test "run iterator: empty cells with background set" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -524,7 +525,7 @@ test "shape" {
     // Get our run iterator
     var shaper = &testdata.shaper;
     var it = shaper.runIterator(
-        testdata.cache,
+        testdata.grid,
         &screen,
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
@@ -559,7 +560,7 @@ test "shape nerd fonts" {
     // Get our run iterator
     var shaper = &testdata.shaper;
     var it = shaper.runIterator(
-        testdata.cache,
+        testdata.grid,
         &screen,
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
@@ -587,7 +588,7 @@ test "shape inconsolata ligs" {
 
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -611,7 +612,7 @@ test "shape inconsolata ligs" {
 
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -643,7 +644,7 @@ test "shape monaspace ligs" {
 
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -675,7 +676,7 @@ test "shape emoji width" {
 
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -715,7 +716,7 @@ test "shape emoji width long" {
     // Get our run iterator
     var shaper = &testdata.shaper;
     var it = shaper.runIterator(
-        testdata.cache,
+        testdata.grid,
         &screen,
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
@@ -752,7 +753,7 @@ test "shape variation selector VS15" {
     // Get our run iterator
     var shaper = &testdata.shaper;
     var it = shaper.runIterator(
-        testdata.cache,
+        testdata.grid,
         &screen,
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
@@ -787,7 +788,7 @@ test "shape variation selector VS16" {
     // Get our run iterator
     var shaper = &testdata.shaper;
     var it = shaper.runIterator(
-        testdata.cache,
+        testdata.grid,
         &screen,
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
@@ -819,7 +820,7 @@ test "shape with empty cells in between" {
     // Get our run iterator
     var shaper = &testdata.shaper;
     var it = shaper.runIterator(
-        testdata.cache,
+        testdata.grid,
         &screen,
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
@@ -857,7 +858,7 @@ test "shape Chinese characters" {
     // Get our run iterator
     var shaper = &testdata.shaper;
     var it = shaper.runIterator(
-        testdata.cache,
+        testdata.grid,
         &screen,
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
@@ -884,13 +885,6 @@ test "shape box glyphs" {
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
 
-    // Setup the box font
-    testdata.cache.group.sprite = font.sprite.Face{
-        .width = 18,
-        .height = 36,
-        .thickness = 2,
-    };
-
     var buf: [32]u8 = undefined;
     var buf_idx: usize = 0;
     buf_idx += try std.unicode.utf8Encode(0x2500, buf[buf_idx..]); // horiz line
@@ -904,7 +898,7 @@ test "shape box glyphs" {
     // Get our run iterator
     var shaper = &testdata.shaper;
     var it = shaper.runIterator(
-        testdata.cache,
+        testdata.grid,
         &screen,
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
@@ -940,7 +934,7 @@ test "shape selection boundary" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             terminal.Selection.init(
@@ -963,7 +957,7 @@ test "shape selection boundary" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             terminal.Selection.init(
@@ -986,7 +980,7 @@ test "shape selection boundary" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             terminal.Selection.init(
@@ -1009,7 +1003,7 @@ test "shape selection boundary" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             terminal.Selection.init(
@@ -1032,7 +1026,7 @@ test "shape selection boundary" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             terminal.Selection.init(
@@ -1068,7 +1062,7 @@ test "shape cursor boundary" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -1087,7 +1081,7 @@ test "shape cursor boundary" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -1106,7 +1100,7 @@ test "shape cursor boundary" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -1125,7 +1119,7 @@ test "shape cursor boundary" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -1157,7 +1151,7 @@ test "shape cursor boundary and colored emoji" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -1176,7 +1170,7 @@ test "shape cursor boundary and colored emoji" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -1193,7 +1187,7 @@ test "shape cursor boundary and colored emoji" {
         // Get our run iterator
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -1223,7 +1217,7 @@ test "shape cell attribute change" {
 
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -1247,7 +1241,7 @@ test "shape cell attribute change" {
 
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -1272,7 +1266,7 @@ test "shape cell attribute change" {
 
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -1297,7 +1291,7 @@ test "shape cell attribute change" {
 
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -1321,7 +1315,7 @@ test "shape cell attribute change" {
 
         var shaper = &testdata.shaper;
         var it = shaper.runIterator(
-            testdata.cache,
+            testdata.grid,
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
@@ -1339,13 +1333,13 @@ test "shape cell attribute change" {
 const TestShaper = struct {
     alloc: Allocator,
     shaper: Shaper,
-    cache: *GroupCache,
+    grid: *SharedGrid,
     lib: Library,
 
     pub fn deinit(self: *TestShaper) void {
         self.shaper.deinit();
-        self.cache.deinit(self.alloc);
-        self.alloc.destroy(self.cache);
+        self.grid.deinit(self.alloc);
+        self.alloc.destroy(self.grid);
         self.lib.deinit();
     }
 };
@@ -1373,17 +1367,11 @@ fn testShaperWithFont(alloc: Allocator, font_req: TestFont) !TestShaper {
     var lib = try Library.init();
     errdefer lib.deinit();
 
-    var cache_ptr = try alloc.create(GroupCache);
-    errdefer alloc.destroy(cache_ptr);
-    cache_ptr.* = try GroupCache.init(alloc, try Group.init(
-        alloc,
-        lib,
-        .{ .points = 12 },
-    ));
-    errdefer cache_ptr.*.deinit(alloc);
+    var c = try Collection.init(alloc);
+    c.load_options = .{ .library = lib };
 
     // Setup group
-    _ = try cache_ptr.group.addFace(.regular, .{ .loaded = try Face.init(
+    _ = try c.add(alloc, .regular, .{ .loaded = try Face.init(
         lib,
         testFont,
         .{ .size = .{ .points = 12 } },
@@ -1391,7 +1379,7 @@ fn testShaperWithFont(alloc: Allocator, font_req: TestFont) !TestShaper {
 
     if (font.options.backend != .coretext) {
         // Coretext doesn't support Noto's format
-        _ = try cache_ptr.group.addFace(.regular, .{ .loaded = try Face.init(
+        _ = try c.add(alloc, .regular, .{ .loaded = try Face.init(
             lib,
             testEmoji,
             .{ .size = .{ .points = 12 } },
@@ -1408,21 +1396,26 @@ fn testShaperWithFont(alloc: Allocator, font_req: TestFont) !TestShaper {
         defer disco_it.deinit();
         var face = (try disco_it.next()).?;
         errdefer face.deinit();
-        _ = try cache_ptr.group.addFace(.regular, .{ .deferred = face });
+        _ = try c.add(alloc, .regular, .{ .deferred = face });
     }
-    _ = try cache_ptr.group.addFace(.regular, .{ .loaded = try Face.init(
+    _ = try c.add(alloc, .regular, .{ .loaded = try Face.init(
         lib,
         testEmojiText,
         .{ .size = .{ .points = 12 } },
     ) });
 
+    const grid_ptr = try alloc.create(SharedGrid);
+    errdefer alloc.destroy(grid_ptr);
+    grid_ptr.* = try SharedGrid.init(alloc, .{ .collection = c }, false);
+    errdefer grid_ptr.*.deinit(alloc);
+
     var shaper = try Shaper.init(alloc, .{});
     errdefer shaper.deinit();
 
     return TestShaper{
         .alloc = alloc,
         .shaper = shaper,
-        .cache = cache_ptr,
+        .grid = grid_ptr,
         .lib = lib,
     };
 }