A tag write over the limit is refused "no space: over 4096 bytes", so its err record says tag: once

The refusal's text began with "tag: ", and the log's err record puts the
file's name before the reason. So the record read `err - col/1/tag: tag:
no space: over 4096 bytes`. The text is now the reason alone, as the
control-character refusal's is, and the record names the file once.

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

2 files changed, 6 insertions, 3 deletions

diff --git a/src/ninep/cols.zig b/src/ninep/cols.zig
index 24fb590c..9185a2bc 100644
--- a/src/ninep/cols.zig
+++ b/src/ninep/cols.zig
@@ -500,7 +500,10 @@ test "a refused write after a truncation leaves every kind of tag as it was, and
         const h = th.call(p, .{ .tag = 2, .op = .open, .node = node, .omode = 1 }).reply.handle;
         const r = th.call(p, .{ .tag = 3, .op = .write, .node = node, .handle = h, .data = big });
         try testing.expectEqual(E.NOSPC, r.errno());
-        try testing.expectEqualStrings("tag: no space: over 4096 bytes", r.reply.ename);
+        try testing.expectEqualStrings("no space: over 4096 bytes", r.reply.ename);
+        // Its err record names the file once: `tag: no space`, never `tag: tag:`.
+        try testing.expect(th.logHas(p, "tag: no space: over 4096 bytes"));
+        try testing.expect(!th.logHas(p, "tag: tag:"));
         _ = th.call(p, .{ .tag = 4, .op = .release, .node = node, .handle = h, .opened = true });
         try testing.expectEqualStrings(before, th.rd(p, node, 0, 1 << 16).bytes);
         // A control character is refused the same way on every kind.
diff --git a/src/ninep/pane.zig b/src/ninep/pane.zig
index de7f7cd4..dc8b4b10 100644
--- a/src/ninep/pane.zig
+++ b/src/ninep/pane.zig
@@ -639,7 +639,7 @@ pub fn tagFault(data: []const u8) ?[]const u8 {
 
 /// A tag write's limit, the same for a pane's, a column's and the
 /// workspace's: whole or not at all.
-pub const e_tag_over = std.fmt.comptimePrint("tag: no space: over {d} bytes", .{limits.max_tag_tail});
+pub const e_tag_over = std.fmt.comptimePrint("no space: over {d} bytes", .{limits.max_tag_tail});
 
 fn writeTag(p: *Pardes, req: Req, pane: *Pane) Reply {
     if (req.data.len == 0) return .{ .tag = req.tag, .written = 0 };
@@ -1314,7 +1314,7 @@ test "a tag write past the limit is refused whole, naming the limit" {
     try testing.expectEqual(E.NOSPC, r.errno());
     // `no space` is what 9ns maps to ENOSPC, so a shell through a mount
     // sees the errno the tree gives.
-    try testing.expect(std.mem.startsWith(u8, r.reply.ename, "tag: no space: over "));
+    try testing.expect(std.mem.startsWith(u8, r.reply.ename, "no space: over "));
     try testing.expectEqualStrings(before, rd(p, tag, 0, 1 << 16).bytes);
 }