A root exec or look that fails logs its err against the pane it ran at

`err - exec: ...` said nothing of where the line ran; the root's exec and
look run at the keyboard's pane, and their err now names it, as a click
there would.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/src/fs.zig b/src/fs.zig
index 6a4c0a33..4414c150 100644
--- a/src/fs.zig
+++ b/src/fs.zig
@@ -1303,6 +1303,9 @@ pub const Namespace = struct {
     /// host work fails (a Save, a Dump), takes it back out of the log, so
     /// an announcement stands only for a builtin that did what it said.
     announced_seq: ?u64 = null,
+    /// The serial of the pane the root's exec or look last ran a line at
+    /// (the keyboard's), 0 before one: its err record names that pane.
+    ran_at: u32 = 0,
     /// Every failure said (Messages.reportFailure), counted: a builtin
     /// that said one while it ran failed.
     failures: u32 = 0,