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, 8 insertions, 1 deletions

diff --git a/src/ninep/tree.zig b/src/ninep/tree.zig
index a85a1873..0d328594 100644
--- a/src/ninep/tree.zig
+++ b/src/ninep/tree.zig
@@ -167,6 +167,7 @@ pub const PaneFile = enum(u5) {
     pty_ctl,
     pty_status,
     pty_data,
+    pty_run,
 
     pub fn fileName(f: PaneFile) []const u8 {
         return switch (f) {
@@ -174,6 +175,7 @@ pub const PaneFile = enum(u5) {
             .pty_ctl => "ctl",
             .pty_status => "status",
             .pty_data => "data",
+            .pty_run => "run",
             else => @tagName(f),
         };
     }
@@ -193,7 +195,7 @@ pub const PaneFile = enum(u5) {
 
     pub fn inPty(f: PaneFile) bool {
         return switch (f) {
-            .pty, .pty_ctl, .pty_status, .pty_data => true,
+            .pty, .pty_ctl, .pty_status, .pty_data, .pty_run => true,
             else => false,
         };
     }
@@ -531,6 +533,7 @@ fn open(p: *Pardes, req: Req, target: Target) Reply {
                     pf.event_reader = pf.event_reader or reader;
                     if (reader) return .{ .tag = req.tag, .handle = reader_handle };
                 },
+                .pty_run => return pty.openRun(p, req, t.serial),
                 .pty_data => if (reads(req.omode)) {
                     if (pf.pty_readers > 0) return failText(req.tag, e_busy, e_in_use);
                     pf.pty_readers = 1;
@@ -569,6 +572,8 @@ fn releaseHandle(p: *Pardes, req: Req) Reply {
     switch (target) {
         .top => {},
         .pane => |t| {
+            // A run's open outlives its pane: it still holds the answer.
+            if (t.file == .pty_run) return pty.releaseRun(p, req);
             if (t.file != .event and t.file != .pty_data) return .{ .tag = req.tag };
             const id = p.paneBySerial(t.serial) orelse return .{ .tag = req.tag };
             const pf = &p.fs.panes[id];
@@ -633,6 +638,8 @@ fn read(p: *Pardes, req: Req, target: Target) Reply {
             .root, .pane => Reply.fail(req.tag, E.PERM),
         },
         .pane => |t| {
+            // A run's answer outlives the pane it ran in.
+            if (t.file == .pty_run and req.handle != 0) return pty.readRun(p, req);
             const id = p.paneBySerial(t.serial) orelse return Reply.fail(req.tag, E.NOENT);
             const pn = p.panes[id].?;
             if (t.file.inPty() and !pn.isTerminal()) return Reply.fail(req.tag, E.NOENT);