A command's exit is told once its output is in, by the pty's state, not a timer

The watcher woke the host a second time 60 ms after the exit by its own clock
while the grace was counted from the reap: a host busy for 10 ms missed it,
and the tag said running for ever and Kill did nothing; and under load exit 0
could land before the last output. As decided, no timer: the exit is told
once it is reaped and the pty says nothing is left (poll: no POLLIN, and no
POLLHUP, which means the end of file is on its way behind the output), else
at that end of file, checked after each chunk of output. The tty host checks
inside its step so the frame shows it. The four hosts' copies are one
host_io.takeExits/commandEof, which close a told command's pty at its end of
file (the fd and the GUI's reader leaked when the exit came first). A
finished command pane whose pty a job it left still holds is not reused, so
that job is not hung up; and the reset before a reuse is SGR 0, not DECSTR,
which ghostty's stream does not implement.

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

1 files changed, 8 insertions, 4 deletions

diff --git a/src/exec.zig b/src/exec.zig
index dfef2dfd..cd2b4089 100644
--- a/src/exec.zig
+++ b/src/exec.zig
@@ -544,9 +544,11 @@ fn runCommand(p: *Pardes, from: usize, line: []const u8) ?usize {
     }
     const src = p.panes[from] orelse return null;
     const dir = Pardes.paneDir(src);
-    const reuse: ?usize = if (src.command != null and src.command_done) from else for (p.panes, 0..) |slot, i| {
+    // Not one whose pty a job it left behind still prints to: reusing it
+    // would hang that job up.
+    const reuse: ?usize = if (src.command != null and src.command_done and !src.command_pty) from else for (p.panes, 0..) |slot, i| {
         const other = slot orelse continue;
-        if (other.command != null and other.command_done and std.mem.eql(u8, other.cwdSlice(), dir)) break i;
+        if (other.command != null and other.command_done and !other.command_pty and std.mem.eql(u8, other.cwdSlice(), dir)) break i;
     } else null;
     if (reuse) |id| {
         const pane = p.panes[id].?;
@@ -558,13 +560,15 @@ fn runCommand(p: *Pardes, from: usize, line: []const u8) ?usize {
         pane.command = owned;
         pane.command_done = false;
         pane.command_status = null;
+        pane.command_pty = true;
         pane.body.mode = .tty;
         // What the last program left the emulator in goes first: the
         // alternate screen left (only if it is there: leaving restores a
         // saved cursor), mouse reports and bracketed paste off, the cursor
-        // shown, then a soft reset (DECSTR) for the rest.
+        // shown, colours reset. (Not DECSTR: ghostty's stream does not
+        // implement it.)
         if (panes.Terminal.onAlternateScreen(pane)) panes.Terminal.feedOutput(p, pane, "\x1b[?1049l");
-        panes.Terminal.feedOutput(p, pane, "\x1b[?1000l\x1b[?1002l\x1b[?1003l\x1b[?1006l\x1b[?2004l\x1b[?25h\x1b[!p");
+        panes.Terminal.feedOutput(p, pane, "\x1b[?1000l\x1b[?1002l\x1b[?1003l\x1b[?1006l\x1b[?2004l\x1b[?25h\x1b[0m");
         echoCommand(p, pane, line);
         p.emit(.{ .spawn = .{ .pane = @intCast(id), .serial = pane.serial, .cwd = .from(pane.cwdSlice()) } });
         noteRun(p, pane, "run", line);