With no pane at all, the root look opens its file and the root exec runs its command in the session's directory

/look and /exec run at the active pane, and with every pane closed they
failed ENOENT, "file does not exist", about a file the writer never
named. Now an exec runs as the workspace tag's would, in the session's
directory: a builtin at the stand-in, a command in a command pane. An
empty window's click now runs a command line too, not only session words.
A look runs from a scratch made as New makes one, which also makes the
column. That scratch is dropped, unannounced, when the look went to
another pane, so opening a file leaves only the file.

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

3 files changed, 72 insertions, 8 deletions

diff --git a/docs/fs.md b/docs/fs.md
index fe78fb19..28c4fef9 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -243,7 +243,9 @@ A line written to `exec` is a middle click:
   second pane. From a pane whose directory is gone nothing runs: `exec:
   <dir>: no such directory` (ENOENT).
 
-The root's `look` and `exec` act at the active pane and log as that pane's;
+The root's `look` and `exec` act at the active pane and log as that pane's
+(with no pane at all, in the session's directory: a look opens its file,
+making a column as `New` does, and an exec runs its command there);
 `/pane/<n>/look` and `exec` at pane n; `/tagexec` and `/col/<n>/exec`
 click in the workspace's or that column's tag, run commands in the session's
 directory, and log as `-`. A pane's word (`Undo`, `Msg`, `Save`) is refused
diff --git a/src/exec.zig b/src/exec.zig
index eed9297a..6070d038 100644
--- a/src/exec.zig
+++ b/src/exec.zig
@@ -644,11 +644,12 @@ pub fn execute(p: *Pardes, id: usize, txt: []const u8) ?usize {
 /// such text may be a bound REPL's. Run by name (`Exec ...`, whose line
 /// comes back through `execute`) or written as a command word, never.
 pub fn executeFrom(p: *Pardes, id: usize, txt: []const u8, from_body: bool) ?usize {
-    // An empty window runs its session words, and nothing else: no pane to
-    // run a command for.
+    // An empty window runs its session words, and a command line in the
+    // session's directory (execDir), as its workspace tag would.
     const pane = p.panes[id] orelse {
-        _ = executeBuiltinLine(p, id, commandText(txt));
-        return null;
+        const cmd = commandText(txt);
+        if (cmd.len == 0 or executeBuiltinLine(p, id, cmd)) return null;
+        return runCommand(p, id, cmd);
     };
     const gesture = from_body and config.commandWord(std.mem.trim(u8, txt, " \t\r\n")) == null;
     const cmd = commandText(txt);
@@ -699,7 +700,9 @@ fn runCommand(p: *Pardes, from: usize, line: []const u8) ?usize {
         p.reportFailure(from, "exec: a command line is at most 1024 bytes");
         return null;
     }
-    const src = p.panes[from] orelse return null;
+    // None asking (an empty window): the session's directory, no pane of
+    // its own to reuse.
+    const src = p.panes[from];
     const dir = p.execDir(from);
     // A directory that is not there runs nothing, as Tty makes nothing
     // there: no pane, and the write fails ENOENT.
@@ -712,7 +715,7 @@ 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_column == null and src.command != null and src.command_done and !src.command_pty) from else for (p.panes, 0..) |slot, i| {
+    const reuse: ?usize = if (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| {
         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;
diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index 0bbc0319..f4e6bb9c 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -192,8 +192,30 @@ pub fn command(p: *Pardes, req: Req, serial: ?u32, exec: bool, in_tag: bool) Rep
             for (text) |c| if ((c < ' ' and c != '\t' and c != '\n') or c == 0x7f) return tree.failText(req.tag, E.INVAL, e_control);
             if (exec) if (tooLong(req, text)) |refusal| return refusal;
             if (!apply) continue;
-            const id = if (serial) |s| p.paneBySerial(s) orelse break else p.active;
+            var id = if (serial) |s| p.paneBySerial(s) orelse break else p.active;
+            // No pane at all: the root's look and exec act in the session's
+            // directory. An exec runs as the workspace tag's; a look from a
+            // scratch made as New makes one (and its column), dropped
+            // unannounced when the look went elsewhere.
+            var scratch: ?usize = null;
+            if (p.panes[id] == null and serial == null and p.anyPane() == null) {
+                if (exec) {
+                    p.exec_header = true;
+                    defer p.exec_header = false;
+                    if (captured(p, req, id, exec, text, true)) |refusal| return refusal;
+                    continue;
+                }
+                const free = p.freeSlot() orelse return Reply.fail(req.tag, E.NOSPC);
+                p.newScratchFor(id, .scratch);
+                if (p.panes[free] == null) return Reply.fail(req.tag, E.NOSPC);
+                p.active = free;
+                id = free;
+                scratch = free;
+            }
             if (p.panes[id] == null) return Reply.fail(req.tag, E.NOENT);
+            defer if (scratch) |s| if (p.active != s) if (p.panes[s]) |sp| if (sp.file) |f| {
+                if (f.content.len == 0) p.removePane(s, null) catch {};
+            };
             p.fs.ran_at = p.panes[id].?.serial;
             p.fs.no_pane_slot = false;
             if (captured(p, req, id, exec, text, in_tag)) |refusal| return refusal;
@@ -2445,6 +2467,43 @@ test "a look that misses file:/re/ names the file, and is logged as its pane's"
     try testing.expect(th.logHas(p, try std.fmt.bufPrint(&want, "err {d} look: {s}/f.txt: no match for regexp", .{ f_serial, dir })));
 }
 
+test "with no pane at all, the root look opens its file and the root exec runs in the session's directory" {
+    const p = try withFile(testing.allocator, "x\n");
+    defer p.deinit();
+    var tmp = testing.tmpDir(.{});
+    defer tmp.cleanup();
+    try tmp.dir.writeFile(testing.io, .{ .sub_path = "f.txt", .data = "file\n" });
+    var buf: [4096]u8 = undefined;
+    const session = buf[0..try tmp.dir.realPath(testing.io, &buf)];
+    @memcpy(p.session_dir[0..session.len], session);
+    p.session_dir_len = @intCast(session.len);
+    const Empty = struct {
+        fn all(q: *Pardes) !void {
+            while (q.anyPane()) |k| _ = wr(q, Node.of(q.panes[k].?.serial, .ctl), "delete\n");
+        }
+    };
+    try Empty.all(p);
+    const look_node = @intFromEnum(tree.TopFile.look);
+    try testing.expectEqual(Status.ok, wr(p, look_node, "f.txt\n").reply.status);
+    var want: [4200]u8 = undefined;
+    const path = try std.fmt.bufPrint(&want, "{s}/f.txt", .{session});
+    var opened: usize = 0;
+    var scratches: usize = 0;
+    for (p.panes) |slot| {
+        const f = (slot orelse continue).file orelse continue;
+        opened += @intFromBool(std.mem.eql(u8, f.path, path));
+        scratches += @intFromBool(std.mem.endsWith(u8, f.path, "/+New"));
+    }
+    try testing.expectEqual(@as(usize, 1), opened);
+    try testing.expectEqual(@as(usize, 0), scratches);
+
+    try Empty.all(p);
+    try testing.expectEqual(Status.ok, wr(p, @intFromEnum(tree.TopFile.exec), "echo hi\n").reply.status);
+    const made = p.panes[p.anyPane().?].?;
+    try testing.expect(made.command != null);
+    try testing.expectEqualStrings(session, made.cwdSlice());
+}
+
 test "the ctl word name refuses a leading blank, as the name file does" {
     const p = try withFile(testing.allocator, "x\n");
     defer p.deinit();