What a root ctl write says is the session's in the log, msg -, not the active pane's

A session builtin written to /ctl runs at the active pane, so its messages were logged under that pane's serial, as if the pane had said them. They are now `msg -`, and still shown on the active pane.

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

1 files changed, 17 insertions, 0 deletions

diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index 8b73e8f7..bb562672 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -344,6 +344,8 @@ pub fn writeRoot(p: *Pardes, req: Req) Reply {
                 continue;
             }
             if (p.panes[p.active] == null) return Reply.fail(req.tag, E.NOENT);
+            p.fs.session_write = true;
+            defer p.fs.session_write = false;
             if (runBuiltin(p, req, p.active, line)) |refusal| return refusal;
         }
     }
@@ -742,6 +744,21 @@ test "a second lock is refused until the holder unlocks or closes, and binds nob
     for (p.fs.opens) |o| try testing.expect(o.node == 0);
 }
 
+test "a message from a root ctl write is the session's in the log" {
+    const p = try withFile(testing.allocator, "x\n");
+    defer p.deinit();
+    p.update(.tick); // the pane's `new` is logged before the log is opened
+    while (p.nextEffect()) |_| {}
+    const log = @intFromEnum(tree.TopFile.log);
+    const f = call(p, .{ .tag = 1, .op = .open, .node = log }).reply.handle;
+    const frozen = call(p, .{ .tag = 2, .op = .read, .node = log, .handle = f, .size = 8192 }).bytes.len;
+    _ = call(p, .{ .tag = 3, .op = .write, .node = log, .handle = f, .data = "follow" });
+    try testing.expectEqual(Status.ok, wr(p, @intFromEnum(tree.TopFile.ctl), "Kill\n").reply.status);
+    // The builtin's name, then what it said: both the session's.
+    try testing.expectEqualStrings("msg - Kill\n", call(p, .{ .tag = 4, .op = .read, .node = log, .handle = f, .off = frozen, .size = 4096 }).bytes);
+    try testing.expectEqualStrings("msg - Kill: nothing running\n", call(p, .{ .tag = 5, .op = .read, .node = log, .handle = f, .off = frozen, .size = 4096 }).bytes);
+}
+
 test "a look takes acme's :addr and file:addr, and a miss changes nothing" {
     const gpa = testing.allocator;
     const p = try withFile(gpa, "foo x foo y\nbar\n");