A command of several lines keeps its pane's tag to one row, and the tag never panics on a longer prefix

A two-line exec made a command pane whose tag prefix held the line's newline,
so the tag ran to a second row and tagTintRange sliced its first row past its
end: panic. acme runs a multi-line selection as one command, and so does
pardes; the tag now shows the line's first row, cut at a character's start,
and '...', tagTintRange stays inside the row it is given, and the '% line'
echo turns the line's newlines into the terminal's, so it does not
staircase.

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

1 files changed, 3 insertions, 2 deletions

diff --git a/src/body_layer.zig b/src/body_layer.zig
index c8e229c4..42b9c082 100644
--- a/src/body_layer.zig
+++ b/src/body_layer.zig
@@ -674,7 +674,8 @@ pub fn paintHeaders(p: *Pardes) !void {
 
 fn tagTintRange(pane: *const Pane, tag: []const u8, prefix_len: usize) ?struct { lo: usize, hi: usize } {
     if (pane.isTerminal()) {
-        var words = std.mem.tokenizeAny(u8, tag[prefix_len..], " \t\r\n");
+        // `tag` is the first row; a prefix longer than it ran to a second.
+        var words = std.mem.tokenizeAny(u8, tag[@min(prefix_len, tag.len)..], " \t\r\n");
         while (words.next()) |word| {
             if (!std.mem.eql(u8, word, "Tty") and !std.mem.startsWith(u8, word, "Tty+")) continue;
             const lo = @intFromPtr(word.ptr) - @intFromPtr(tag.ptr);
@@ -687,7 +688,7 @@ fn tagTintRange(pane: *const Pane, tag: []const u8, prefix_len: usize) ?struct {
         if (pane.prompt == .name) pane.input.own orelse file.path else file.path
     else if (pane.image) |state| blk: {
         // Image tags put renderer controls before the path.
-        start = std.mem.lastIndexOf(u8, tag[0..prefix_len], state.path) orelse return null;
+        start = std.mem.lastIndexOf(u8, tag[0..@min(prefix_len, tag.len)], state.path) orelse return null;
         break :blk state.path;
     } else if (comptime pdf_enabled) blk: {
         break :blk if (pane.pdf) |state| state.path else return null;