Run a line at a terminal's prompt through pty/run and read how it ended

/pane/<n>/pty/run takes factotum's rpc shape: write one line on an open,
read the answer on that same open. The answer is exit N once the command
ended and the shell is back at a prompt; busy at once when a command runs,
text is typed at the prompt, or the shell has not drawn its first prompt;
error not run when the shell refused the line without running it (fish on
a syntax error keeps it on the prompt, so it is taken back with Ctrl-U);
error shell gone when the pane closes or its shell is replaced; error no
prompt marks for a shell pardes could not instrument.

The end comes from the shell's OSC 133 marks. ghostty parses D's exit
status and drops it, so the stream now runs through a handler that wraps
ghostty's and follows prompt -> input -> running -> done. The marks pardes
injects into bash and fish carry aid=pardes and only those count, so fish
4's own marks (which doubled ours), a nested shell's, and a stray 133;D in
printed output are ignored.

Checked end to end against real bash and fish: false, exit 7, a syntax
error, sleep, busy while running, and the pane closing mid-command.

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

1 files changed, 7 insertions, 1 deletions

diff --git a/src/ninep/pane.zig b/src/ninep/pane.zig
index 40d292c0..61073a55 100644
--- a/src/ninep/pane.zig
+++ b/src/ninep/pane.zig
@@ -41,6 +41,10 @@ pub const State = struct {
     tag_snap: std.ArrayList(u8) = .empty,
     pty_readers: u16 = 0,
     pty_out: events.Queue = .{},
+    /// The pty/run open waiting on this shell's current command.
+    run: ?u8 = null,
+    /// The host started a shell it could not teach to mark its prompts.
+    unmarked: bool = false,
     /// Installed during this update; /log hears about it once the update ends
     /// and the pane has its file, name and place.
     unannounced: bool = false,
@@ -225,7 +229,7 @@ pub fn fileSize(p: *Pardes, id: usize, f: PaneFile) u64 {
         .pty_status => pty.status_len,
         .pty_ctl => pty.ctlLen(pane),
         .pty_data => events.pending(&pf.pty_out),
-        .dir, .errors, .pty => 0,
+        .dir, .errors, .pty, .pty_run => 0,
     };
 }
 
@@ -293,6 +297,7 @@ pub fn read(p: *Pardes, req: Req, id: usize, pane: *Pane, file: PaneFile) Reply
         .pty_status => pty.readStatus(p, req, id, pane),
         .pty_data => pty.readData(p, req, pf),
         .pty_ctl => pty.readCtl(p, req, pane),
+        .pty_run => pty.readRun(p, req),
         .dir, .errors, .pty => Reply.fail(req.tag, E.PERM),
     };
 }
@@ -386,6 +391,7 @@ pub fn write(p: *Pardes, req: Req, id: usize, pane: *Pane, file: PaneFile) Reply
             Reply.fail(req.tag, E.IO),
         .pty_ctl => pty.writeCtl(p, req, id),
         .pty_data => pty.writeData(p, req, id),
+        .pty_run => pty.writeRun(p, req, id, pane),
         .dir, .pty, .pty_status => Reply.fail(req.tag, E.PERM),
     };
 }