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]>

5 files changed, 29 insertions, 13 deletions

diff --git a/src/fs-help.txt b/src/fs-help.txt
index 60ce4d4e..9e6a9240 100644
--- a/src/fs-help.txt
+++ b/src/fs-help.txt
@@ -15,7 +15,7 @@ layout      a line per column: serial index x width current|notcurrent empty|ful
 tag         the workspace tag, tagexec a word as a click in it; col/<serial>/ a column's tag, ctl (Delcol Joincol New Tty), exec; rmdir: empty only
 pane/new    open it to make a pane (named +New) in the active column, filling it if empty; the read answers its serial
 pane/<n>/   name body tag ctl addr dot limit data xdata sel dirty mark scroll errors (write-only:
-            appended to its directory's +Errors pane) event look exec, pty/ on terminals; rmdir closes
+            appended to its directory's +Errors pane) event look exec tagexec, pty/ on terminals; rmdir closes
 os/, src/   the host filesystem; the editor's own sources
 
 $m below: $NINE_MOUNT/pardes/<pid|NAME>; $NINE_MOUNT under 9ns --unix; PARDES_MOUNT in a Tty9p shell.
diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index eb8ed292..f8623903 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -168,7 +168,7 @@ pub fn completeEnd(p: *Pardes, data: []const u8) usize {
 /// clicked text itself, so it may not be empty or carry control characters.
 /// A null `serial` clicks at whichever pane is active as each line runs,
 /// which is what the root's own look and exec mean; a serial stays put.
-pub fn command(p: *Pardes, req: Req, serial: ?u32, exec: bool) Reply {
+pub fn command(p: *Pardes, req: Req, serial: ?u32, exec: bool, in_tag: bool) Reply {
     for ([2]bool{ false, true }) |apply| {
         if (apply) p.fs.results_len = 0;
         var it = Messages.init(p, req.data);
@@ -181,7 +181,7 @@ pub fn command(p: *Pardes, req: Req, serial: ?u32, exec: bool) Reply {
             const id = if (serial) |s| p.paneBySerial(s) orelse break else p.active;
             if (p.panes[id] == null) return Reply.fail(req.tag, E.NOENT);
             p.fs.no_pane_slot = false;
-            run(p, id, exec, text, false);
+            run(p, id, exec, text, in_tag);
             // A pane it would have opened had no slot: the write fails, and
             // a look reads back nothing.
             if (p.fs.no_pane_slot) {
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);
+}
diff --git a/src/ninep/pty.zig b/src/ninep/pty.zig
index 76cef83b..6b2abd0a 100644
--- a/src/ninep/pty.zig
+++ b/src/ninep/pty.zig
@@ -453,7 +453,7 @@ test "a pane that is not a terminal has no pty/ at all" {
 
     var buf: [32]th.Dirent = undefined;
     const files = th.dirents(rdir(p, dir, 0).bytes, &buf);
-    try testing.expectEqual(@as(usize, 17), files.len);
+    try testing.expectEqual(@as(usize, 18), files.len);
     try testing.expect(th.nameAt(files, "pty") == null);
 
     try testing.expectEqual(E.NOENT, look_up(p, dir, "pty_ctl").errno());
@@ -474,7 +474,7 @@ test "a terminal pane's pty/ holds exactly ctl, status and data" {
 
     var buf: [32]th.Dirent = undefined;
     const files = th.dirents(rdir(p, dir, 0).bytes, &buf);
-    try testing.expectEqual(@as(usize, 18), files.len);
+    try testing.expectEqual(@as(usize, 19), files.len);
     try testing.expect(th.nameAt(files, "pty").?.dir);
 
     const inside = th.dirents(rdir(p, Node.of(serial, .pty), 0).bytes, &buf);
diff --git a/src/ninep/tree.zig b/src/ninep/tree.zig
index f45a1a90..398824d5 100644
--- a/src/ninep/tree.zig
+++ b/src/ninep/tree.zig
@@ -259,6 +259,9 @@ pub const PaneFile = enum(u5) {
     event,
     look,
     exec,
+    /// A word run as a click in the pane's tag, as /tagexec is in the
+    /// workspace's and col/<n>/exec in a column's.
+    tagexec,
     pty,
     pty_ctl,
     pty_status,
@@ -965,7 +968,7 @@ fn linesFile(target: Target) bool {
     return switch (target) {
         .top => |f| f == .look or f == .exec or f == .ctl or f == .tagexec,
         .col => |c| c.file == .ctl or c.file == .exec,
-        .pane => |t| t.file == .look or t.file == .exec or t.file == .ctl,
+        .pane => |t| t.file == .look or t.file == .exec or t.file == .ctl or t.file == .tagexec,
     };
 }
 
@@ -974,7 +977,7 @@ fn resultsFile(target: Target) bool {
     return switch (target) {
         .top => |f| f == .look or f == .exec or f == .tagexec,
         .col => |c| c.file == .exec,
-        .pane => |t| t.file == .look or t.file == .exec,
+        .pane => |t| t.file == .look or t.file == .exec or t.file == .tagexec,
     };
 }
 
@@ -1025,7 +1028,7 @@ fn write(p: *Pardes, req: Req, target: Target) Reply {
 fn writeNow(p: *Pardes, req: Req, target: Target) Reply {
     switch (target) {
         .top => |f| return switch (f) {
-            .look, .exec => ctl.command(p, req, null, f == .exec),
+            .look, .exec => ctl.command(p, req, null, f == .exec, false),
             .log => events.writeLog(p, req),
             .focus => ctl.writeFocus(p, req),
             .ctl => ctl.writeRoot(p, req),
@@ -1234,10 +1237,10 @@ test "readdir lists the root and a pane directory without creating anything" {
 
     const dir = rdir(p, Node.of(serial, .dir), 0);
     const files = th.dirents(dir.bytes, &buf);
-    try testing.expectEqual(@as(usize, 17), files.len);
+    try testing.expectEqual(@as(usize, 18), files.len);
     for ([_][]const u8{
         "name",  "body", "tag",    "ctl",    "addr",   "dot",  "limit", "data", "xdata",
-        "sel",   "dirty", "mark",  "scroll", "errors", "event", "look", "exec",
+        "sel",   "dirty", "mark",  "scroll", "errors", "event", "look", "exec", "tagexec",
     }, 0..) |name, i|
         try testing.expectEqualStrings(name, files[i].name);
     try testing.expect(th.nameAt(files, ".") == null);