Scroll a tag taller than its rows to keep its caret in view

A tag shows at most eight rows, so a longer one (a 9P write of many lines, or
`o` in the tag) put its caret on a line that was never drawn. Pane, column and
workspace tags now keep a first line on screen that follows the caret while
they have the keyboard, and the pointer and the pane text count their rows
from it.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 4 insertions, 3 deletions

diff --git a/src/edit.zig b/src/edit.zig
index edc86dd2..42032168 100644
--- a/src/edit.zig
+++ b/src/edit.zig
@@ -131,12 +131,13 @@ pub fn clipYank(p: *Pardes, pane: *Pane, main_only: bool) void {
 }
 
 /// tag + '\n' + body: the full selectable pane text, a row to a screen row
-/// (the tag's lines first, as many as it shows)
+/// (the tag's lines first, the ones it shows)
 pub fn paneText(p: *Pardes, pane: *Pane) ![]u8 {
     const arena = p.scratch.allocator();
     const tag = try tagline.tagText(p, arena, pane);
-    const cut = modal.lineStartOffset(tag, pane.tag_rows);
-    const shown = if (cut < tag.len) tag[0 .. cut - 1] else tag;
+    const from = modal.lineStartOffset(tag, pane.tag_top);
+    const cut = modal.lineStartOffset(tag, pane.tag_top + pane.tag_rows);
+    const shown = if (cut < tag.len) tag[from .. cut - 1] else tag[from..];
     return std.fmt.allocPrint(arena, "{s}\n{s}", .{ shown, try body_layer.bodyText(p, arena, pane) });
 }