An err record's reason that names its file already is not prefixed twice

A refused look logged `err N look: look: no space for a pane...`: the
reason began with the file's name, and the record put it before it again.

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

2 files changed, 8 insertions, 2 deletions

diff --git a/src/ninep/events.zig b/src/ninep/events.zig
index 45569b22..3da6f723 100644
--- a/src/ninep/events.zig
+++ b/src/ninep/events.zig
@@ -216,9 +216,12 @@ pub fn noteError(p: *Pardes, req: Req, reply: Reply) void {
         };
     }
     var buf: [256]u8 = undefined;
+    // A reason that names its file already (`look: no space...` from a
+    // look) is not prefixed twice: `err 3 look: no space...`.
+    const reason = if (why.len > file.len + 2 and std.ascii.startsWithIgnoreCase(why, file) and std.mem.startsWith(u8, why[file.len..], ": ")) why[file.len + 2 ..] else why;
     // A long reason is cut between words, with an ellipsis, never mid-word.
-    const kept = pardes.Messages.clip(why, 200);
-    const record = std.fmt.bufPrint(&buf, "err {s} {s}: {s}{s}\n", .{ serial, file, kept, if (kept.len < why.len) "…" else "" }) catch return;
+    const kept = pardes.Messages.clip(reason, 200);
+    const record = std.fmt.bufPrint(&buf, "err {s} {s}: {s}{s}\n", .{ serial, file, kept, if (kept.len < reason.len) "…" else "" }) catch return;
     for (record[0 .. record.len - 1]) |*c| if (c.* < ' ') {
         c.* = ' ';
     };
diff --git a/src/ninep/tree.zig b/src/ninep/tree.zig
index c089c31d..9d2027bf 100644
--- a/src/ninep/tree.zig
+++ b/src/ninep/tree.zig
@@ -1470,6 +1470,9 @@ test "at the pane cap, pane/new, look and New each say so, and look reads back e
     const looked = th.wr(p, look_node, try std.fmt.bufPrint(&line, "{s}/f.txt\n", .{dir}));
     try testing.expect(looked.errno() != 0);
     try testing.expect(std.mem.indexOf(u8, looked.reply.ename, said) != null);
+    // Its err record names the file once: `look: no space...`.
+    try testing.expect(th.logHas(p, "look: no space"));
+    try testing.expect(!th.logHas(p, "look: look:"));
     try testing.expectEqualStrings("", th.rd(p, look_node, 0, 64).bytes);
     // New from a pane's ctl fails as well.
     const ctl_node = Node.of(p.panes[0].?.serial, .ctl);