A command run from a column's tag gets its pane in that column

A command from a column's tag ran in a command pane at the foot of the
last column, however far from the tag, and could reuse a finished one
anywhere. It now goes to the tag's column, under both placements, and
reuses only a finished command pane in that column.

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

3 files changed, 31 insertions, 5 deletions

diff --git a/docs/tags.md b/docs/tags.md
index 2cd3f16b..3db7f465 100644
--- a/docs/tags.md
+++ b/docs/tags.md
@@ -273,7 +273,9 @@ never into a new column:
 - `New` goes into its own column, the bottom half of its last pane
   (look.c:921-923);
 - a command pane or a `+Errors` pane goes to the last column, the bottom
-  half of its last pane (util.c:94-98).
+  half of its last pane (util.c:94-98); a command run from a column's tag
+  goes to that column instead, and reuses a finished command pane only in
+  that column.
 
 `Placement pardes` is what pardes did before: an empty column whose tag asked,
 or has the keyboard, is filled; a scratch goes right under the pane that asked;
diff --git a/src/exec.zig b/src/exec.zig
index ddb89d33..6e6f528b 100644
--- a/src/exec.zig
+++ b/src/exec.zig
@@ -585,8 +585,11 @@ fn runCommand(p: *Pardes, from: usize, line: []const u8) ?usize {
     const dir = p.execDir(from);
     // 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| {
+    // 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_column == null and 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 (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;
     } else null;
     if (reuse) |id| {
@@ -838,8 +841,10 @@ pub fn placeNew(p: *Pardes, from: usize, origin: ?usize, id: usize, kind: NewPan
             // New: the bottom half of the last pane in its own column
             // (look.c:921-923, et->col).
             .scratch => layout.acmePlace(p, p.exec_column orelse columnOf(p, from), null, id),
-            // +Errors, a command's output: the last column (util.c:94-98).
-            .command, .errors => layout.acmePlace(p, p.ncol - 1, null, id),
+            // +Errors, a command's output: the last column (util.c:94-98);
+            // a command run from a column's tag, that column.
+            .command => layout.acmePlace(p, p.exec_column orelse p.ncol - 1, null, id),
+            .errors => layout.acmePlace(p, p.ncol - 1, null, id),
             // makenewwindow(nil) for 9P's new (acme.c:877), else (t).
             .fs => layout.acmePlace(p, acmeColumn(p, from), null, id),
             .shell, .doc => layout.acmePlace(p, acmeColumn(p, from), asked, id),
@@ -928,7 +933,7 @@ fn pardesPlace(p: *Pardes, from: usize, id: usize, kind: NewPane) void {
         .shell => belowParent(p, from, id),
         .doc, .errors => pardesDoc(p, from, id),
         .command => {
-            const rc = p.ncol - 1;
+            const rc = p.exec_column orelse p.ncol - 1;
             if (p.col_n[rc] > 0) belowParent(p, p.col_panes[rc][p.col_n[rc] - 1], id) else layout.insert(p, rc, 0, id);
         },
     }
diff --git a/src/ninep/cols.zig b/src/ninep/cols.zig
index c55c1e73..ef2e6cbd 100644
--- a/src/ninep/cols.zig
+++ b/src/ninep/cols.zig
@@ -337,3 +337,22 @@ test "a word run from the workspace's or a column's tag runs in the session's di
     const made = p.paneBySerial(p.fs.results[0]).?;
     try testing.expectEqualStrings(pardes.Pardes.paneDir(p.panes[0].?), pardes.Pardes.paneDir(p.panes[made].?));
 }
+
+test "a command run from a column's tag gets its pane in that column, not the last" {
+    const p = try th.withFile(testing.allocator, "x\n");
+    defer p.deinit();
+    p.newColumn(p.active);
+    p.newScratchFor(p.active, .fs); // fills the new, right column
+    p.sync();
+    const left = layout.columnSerial(p, 0);
+    try testing.expectEqual(tree.Status.ok, th.wr(p, Node.ofCol(left, .exec), "true\n").reply.status);
+    const made = p.paneBySerial(p.fs.results[0]).?;
+    try testing.expectEqual(@as(usize, 0), layout.findPane(p, made).?.col);
+    // Finished, it is reused only by its own column's commands.
+    p.panes[made].?.command_done = true;
+    p.panes[made].?.command_pty = false;
+    try testing.expectEqual(tree.Status.ok, th.wr(p, Node.ofCol(layout.columnSerial(p, 1), .exec), "true\n").reply.status);
+    const other = p.paneBySerial(p.fs.results[0]).?;
+    try testing.expect(other != made);
+    try testing.expectEqual(@as(usize, 1), layout.findPane(p, other).?.col);
+}