`> exec` through a mount no longer hangs the editor, and a close holding a last line is answered at once: the line runs at the editor's next step

A shell's truncating open of exec (or look, ctl, log, pager) sends a
setattr that changes nothing; it waited for the editor to be quiet, and
through a 9ns mount that quiet could never come: 9ns answers nothing else
on the mount while the setattr is out, and the editor's step may be out
reading a pane's file through it. This was the "truncating open of exec
hangs, only in selfmount" mystery. Only a truncate of a pane's file or a
tag waits now.

A close holding a last line with no newline hands it to the editor's step
(tree.runClosedLines, beside fillClosedPagers), as a /pager close does, and
is answered at once; a refusal is the log's err.

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

1 files changed, 2 insertions, 0 deletions

diff --git a/src/pardes.zig b/src/pardes.zig
index 5d9f8606..612a09aa 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -5756,6 +5756,8 @@ pub const Pardes = struct {
         ctlfs.pane.flushPausedBatch(p);
         // ...and what a /pager open was written before its close.
         ctlfs.ctl.fillClosedPagers(p);
+        // ...and the last line of an open closed with no newline after it.
+        ctlfs.runClosedLines(p);
         while (p.nextQueued()) |ev| p.update(ev);
         while (p.nextEffect()) |e| p.perform(e);
         turn.settle();