A pane has a tagexec: a word run as a click in its tag

The workspace had /tagexec and a column its exec, but a pane's own tag
could be clicked only by an event record. pane/<n>/tagexec runs each line
as a click in that pane's tag (never redirected to its event reader, as a
header's is not) and reads back what it touched. The README, fs.md and
the skill list it.

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

1 files changed, 16 insertions, 3 deletions

diff --git a/src/ninep/pane.zig b/src/ninep/pane.zig
index 8cac55d6..4a50b9a1 100644
--- a/src/ninep/pane.zig
+++ b/src/ninep/pane.zig
@@ -259,7 +259,7 @@ pub fn fileSize(p: *Pardes, id: usize, f: PaneFile) u64 {
         .dot => range_len,
         .limit => if (pf.limit == null) 0 else range_len,
         .dirty, .mark, .scroll => 2,
-        .look, .exec => ctl.resultsLen(p),
+        .look, .exec, .tagexec => ctl.resultsLen(p),
         // What the next read would answer, which a client can see without
         // parking on it.
         .event => if (pf.events.peek()) |record| record.len else 0,
@@ -328,7 +328,7 @@ pub fn read(p: *Pardes, req: Req, id: usize, pane: *Pane, file: PaneFile) Reply
         .dirty => readFlag(p, req, dirtyOf(pane)),
         .mark => readFlag(p, req, !pf.nomark),
         .scroll => readFlag(p, req, !pf.noscroll),
-        .look, .exec => ctl.readResults(p, req),
+        .look, .exec, .tagexec => ctl.readResults(p, req),
         .event => events.readQueue(p, req, &pf.events),
         .pty_status => pty.readStatus(p, req, id, pane),
         .pty_data => pty.readData(p, req, pf),
@@ -420,7 +420,9 @@ pub fn write(p: *Pardes, req: Req, id: usize, pane: *Pane, file: PaneFile) Reply
         .data, .xdata => writeData(p, req, pane),
         .sel => writeSel(p, req, pane),
         .dirty, .mark, .scroll => writeFlag(p, req, pane, file),
-        .look, .exec => ctl.command(p, req, pane.serial, file == .exec),
+        .look, .exec => ctl.command(p, req, pane.serial, file == .exec, false),
+        // A click in its tag: never an event reader's to hear (cols.writeExec).
+        .tagexec => ctl.command(p, req, pane.serial, true, true),
         .event => events.writeEvent(p, req, id),
         .errors => if (appendErrors(p, id, req.data)) |took|
             .{ .tag = req.tag, .written = @intCast(took) }
@@ -1275,3 +1277,14 @@ test "a limit write that fails keeps the limit a truncation cleared before it" {
     _ = call(p, .{ .tag = 3, .op = .release, .node = limit });
     try testing.expectEqualStrings("", rd(p, limit, 0, 100).bytes);
 }
+
+test "a pane's tagexec runs a word as a click in its tag, and reads back what it touched" {
+    const gpa = testing.allocator;
+    const p = try withFile(gpa, "x\n");
+    defer p.deinit();
+    const serial = serialOf(p);
+    try testing.expectEqual(Status.ok, wr(p, Node.of(serial, .tagexec), "Msg from the tag\n").reply.status);
+    try testing.expect(th.logHas(p, "from the tag"));
+    var want: [16]u8 = undefined;
+    try testing.expectEqualStrings(try std.fmt.bufPrint(&want, "{d}\n", .{serial}), rd(p, Node.of(serial, .tagexec), 0, 64).bytes);
+}