1 files changed, 14 insertions, 2 deletions
diff --git a/src/exec.zig b/src/exec.zig
index 47484105..ca48bed1 100644
--- a/src/exec.zig
+++ b/src/exec.zig
@@ -766,10 +766,13 @@ fn runCommand(p: *Pardes, from: usize, line: []const u8) ?usize {
     // would hang that job up.
     // From a column's tag, only a finished pane in that column is reused,
     // as the new one goes in that column (placeNew).
-    const reuse: ?usize = if (!p.exec_header and p.exec_column == null and src != null and src.?.command != null and src.?.command_done and !src.?.command_pty) from else for (p.panes, 0..) |slot, i| {
+    // Nor one leased: an open that was answered its serial and is still
+    // open reads that pane's output, which another client's command must
+    // not replace; a new pane runs it instead.
+    const reuse: ?usize = if (!p.exec_header and p.exec_column == null and src != null and src.?.command != null and src.?.command_done and !src.?.command_pty and !leased(p, src.?.serial)) from else for (p.panes, 0..) |slot, i| {
         const other = slot orelse continue;
         if (p.exec_column) |c| if (if (layout.findPane(p, i)) |f| f.col != c else true) continue;
-        if (other.command != null and other.command_done and !other.command_pty 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) and !leased(p, other.serial)) break i;
     } else null;
     if (reuse) |id| {
         const pane = p.panes[id].?;
@@ -812,6 +815,15 @@ fn runCommand(p: *Pardes, from: usize, line: []const u8) ?usize {
     return free;
 }
 
+/// Whether an open of a look or exec file holds `serial` from its own write
+/// (tree.Open.results): its client is reading that pane.
+fn leased(p: *const Pardes, serial: u32) bool {
+    for (p.fs.opens) |o| if (o.node != 0 and o.results.wrote) {
+        if (std.mem.indexOfScalar(u32, o.results.list[0..o.results.len], serial) != null) return true;
+    };
+    return false;
+}
+
 /// The serial a command's `$winid` names: the pane it was run from, none
 /// (0) from a column's or the workspace's tag.
 fn winid(p: *const Pardes, src: ?*Pane) u32 {