An Edit block cut short through exec is an err, not a msg

An exec write does not fail for what its command says, so an a/c/i text
or { group cut short by a write that ended early was only a msg, easy to
miss. Over 9P, that failure (a truncated write, not a command's) is now
logged as an err record naming exec; the pane still says it.

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

1 files changed, 13 insertions, 0 deletions

diff --git a/src/ninep/tree.zig b/src/ninep/tree.zig
index 54d21da6..27091112 100644
--- a/src/ninep/tree.zig
+++ b/src/ninep/tree.zig
@@ -1547,3 +1547,16 @@ test "an a, c or i text still open when its open closes fails there too and chan
     try testing.expect(th.logHas(p, "not ended by a . line"));
     try testing.expectEqualStrings("abc\n", p.panes[0].?.file.?.content);
 }
+
+test "an a, c or i text cut short through exec is an err in the log, not a msg" {
+    const p = try th.withFile(testing.allocator, "abc\n");
+    defer p.deinit();
+    const exec = Node.of(serialOf(p), .exec);
+    const c = call(p, .{ .tag = 1, .op = .open, .node = exec, .omode = 1 }).reply.handle;
+    _ = call(p, .{ .tag = 2, .op = .write, .node = exec, .handle = c, .data = "Edit $a\nhalf\n" });
+    _ = call(p, .{ .tag = 3, .op = .release, .node = exec, .handle = c, .opened = true });
+    var want: [64]u8 = undefined;
+    try testing.expect(th.logHas(p, try std.fmt.bufPrint(&want, "err {d} exec: Edit: a, c or i text not ended", .{serialOf(p)})));
+    try testing.expect(!th.logHas(p, "msg 1 Edit: a, c or i"));
+    try testing.expectEqualStrings("abc\n", p.panes[0].?.file.?.content);
+}