A pty/ctl exec that cannot start its shell keeps the one running

Each host closed the running shell before it forked the new one, so an exec whose shell failed left the pane with none and later runs answered error shell gone. A shell not there is now refused up front, and every host starts the new shell first, replacing the old only once the close-on-exec pipe says it ran; a failure there is only said (restartFailed).

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

1 files changed, 7 insertions, 0 deletions

diff --git a/src/pardes.zig b/src/pardes.zig
index d2fd795b..76ec2176 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -5353,6 +5353,13 @@ pub const Pardes = struct {
         }
     }
 
+    /// A shell started again in a terminal whose shell runs (pty/ctl's
+    /// exec) did not start: the host kept the running one, so only said.
+    pub fn restartFailed(p: *Pardes, id: u8, err: anyerror) void {
+        if (p.panes[id] == null) return;
+        p.sayShellFailure(id, err);
+    }
+
     fn sayShellFailure(p: *Pardes, id: u8, err: anyerror) void {
         const pane = p.panes[id] orelse return;
         if (err == error.FileNotFound or err == error.NotDir) {