1 files changed, 29 insertions, 0 deletions
diff --git a/src/body_layer.zig b/src/body_layer.zig
index 3b5ee795..14fb91ec 100644
--- a/src/body_layer.zig
+++ b/src/body_layer.zig
@@ -3,6 +3,7 @@
 const std = @import("std");
 const pardes = @import("pardes.zig");
 const config = @import("config.zig");
+const limits = @import("memory.zig").limits;
 
 pub const Metrics = struct {
     body_w: u16 = 1,
@@ -18,9 +19,24 @@ pub const Layer = struct {
     cols: u16 = 0,
     rows: u16 = 0,
     context_rows: u16 = 0,
+    context_separators: std.bit_set.StaticBitSet(limits.wrap_rows) = .initEmpty(),
     cells: []pardes.Cell = &.{},
     cursor: ?struct { x: u16, y: u16, bar: bool = false } = null,
 
+    pub fn setContextLines(layer: *Layer, lines: []const i32) void {
+        layer.context_separators = .initEmpty();
+        const count = @min(lines.len, layer.context_rows);
+        var row: usize = 0;
+        while (row + 1 < count and row < limits.wrap_rows) : (row += 1) {
+            if (lines[row + 1] != lines[row] +| 1) layer.context_separators.set(row);
+        }
+    }
+
+    pub fn hasContextBorderAfter(layer: *const Layer, row: usize) bool {
+        if (row >= layer.context_rows or row >= limits.wrap_rows) return false;
+        return row + 1 == layer.context_rows or layer.context_separators.isSet(row);
+    }
+
     pub fn rowTop(layer: *const Layer, row: u16, body_h: f32, tagline_h: f32) f32 {
         const body = @max(1, body_h);
         const tag = std.math.clamp(tagline_h, 1, body);
@@ -78,3 +94,16 @@ test "compact body layer rows fill reclaimed height and invert exact boundaries"
     try std.testing.expect(layer.hitAt(39.99, 80, 10, 20, 6, 12) == null);
     try std.testing.expect(layer.hitAt(std.math.nan(f32), 80, 10, 20, 6, 12) == null);
 }
+
+test "compact context borders separate source gaps and preserve multiline headers" {
+    var layer: Layer = .{ .context_rows = 6 };
+    layer.setContextLines(&.{ 3, 4, 8, 9, 10, 17 });
+    const expected = [_]bool{ false, true, false, false, true, true, false };
+    for (expected, 0..) |border, row| try std.testing.expectEqual(border, layer.hasContextBorderAfter(row));
+    layer.context_rows = 2;
+    layer.setContextLines(&.{ 9, 10 });
+    try std.testing.expect(!layer.hasContextBorderAfter(0));
+    try std.testing.expect(layer.hasContextBorderAfter(1));
+    try std.testing.expect(!layer.hasContextBorderAfter(4));
+    try std.testing.expect(!layer.context_separators.isSet(4));
+}