Tty in a missing directory fails and makes no pane; a shell that never started answers runs

The host could not start the shell (its chdir failed), and the pane stayed
with no pty: a run written to it waited for a prompt for ever. Tty now
refuses a directory that is not there, `Tty: <dir>: no such directory`,
before making a pane; and a terminal whose shell the host could not start
(Pardes.shellFailed, from each host's spawn) answers any run with
`error shell gone`.

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

1 files changed, 11 insertions, 0 deletions

diff --git a/src/pardes.zig b/src/pardes.zig
index 002ff6f9..3a574dc9 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -5010,6 +5010,7 @@ pub const Pardes = struct {
     pub fn acknowledgeShell(p: *Pardes, id: usize, executable: []const u8, prompt_marks: bool) void {
         if (id < MAX_PANES) if (p.panes[id]) |pane| {
             ctlfs.pty.shellGone(p, pane, true); // a respawn replaced whatever ran
+            pane.shell_failed = false;
             pane.fs.unmarked = !prompt_marks;
             // The tag's Tty word names the shell the host ran, and a click
             // on it (`Tty+fish`) opens another of the same.
@@ -5230,6 +5231,16 @@ pub const Pardes = struct {
             p.emit(.{ .watch = .{ .pane = id, .on = true } });
     }
 
+    /// A terminal whose shell could not be started: said, and a run waiting
+    /// on it, or written to it from now on, hears `error shell gone`
+    /// rather than wait for a prompt that never comes.
+    pub fn shellFailed(p: *Pardes, id: u8, err: anyerror) void {
+        const pane = p.panes[id] orelse return;
+        pane.shell_failed = true;
+        ctlfs.pty.shellGone(p, pane, false);
+        p.reportError(id, "shell", err);
+    }
+
     pub fn saveFailed(p: *Pardes, id: u8, path: []const u8, err: anyerror) void {
         if (p.panes[id]) |pane| if (pane.file) |*f| {
             // The `-%` spelling fs.zig already uses for "make this dirty".