A builtin's Verbose announcement is logged only when it succeeds

A failure said while it ran (Exit's refusal, a Del refused) or later by
the host (a Save's write, a Dump's) left `msg N Save` in the log as if it
had worked. The announcement's record is remembered and taken back out
on either, unless a follower read it already. A refused pane/new logs its
err alone, and a failed Dump says its reason in words (`file not found`,
not `FileNotFound`) so its msg goes and the err is the one record.

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

1 files changed, 7 insertions, 0 deletions

diff --git a/src/ninep/tree.zig b/src/ninep/tree.zig
index 69b89f53..ed0e0352 100644
--- a/src/ninep/tree.zig
+++ b/src/ninep/tree.zig
@@ -717,7 +717,12 @@ fn open(p: *Pardes, req: Req, target: Target) Reply {
             .new => {
                 const slot = p.freeSlot() orelse return failText(req.tag, E.NOSPC, std.fmt.bufPrint(&p.fs.ename, "pane/new: " ++ pardes.Messages.no_pane_slots, .{pardes.MAX_PANES}) catch "no space for a pane");
                 p.fs.no_pane_slot = false;
+                // Refused, the open's err is the one record of it (the
+                // one rule): no msg besides.
+                p.fs.capturing = true;
                 p.newScratchFor(p.active, .fs);
+                p.fs.capturing = false;
+                p.fs.failure_len = 0;
                 const made = p.panes[slot] orelse return Reply.fail(req.tag, E.NFILE);
                 // No room in its column: it closes at the step's end.
                 if (p.unplaced.isSet(slot)) return failText(req.tag, E.NOSPC, p.fs.ename[0..p.fs.no_pane_slot_len]);
@@ -1448,6 +1453,8 @@ test "at the pane cap, pane/new, look and New each say so, and look reads back e
     try testing.expectEqual(E.NOSPC, refused.errno());
     try testing.expect(std.mem.endsWith(u8, refused.reply.ename, said));
     try testing.expect(th.logHas(p, said));
+    // Its err alone says it: no msg besides (the one rule).
+    try testing.expect(!th.logHas(p, "New: no space"));
     // A look that would open a pane fails its write, and says the same.
     var tmp = testing.tmpDir(.{});
     defer tmp.cleanup();