Errors are said in words, and a refusal names what it takes

A failure read `Del k|j: InvalidArgument`, `Kill: NoSuchCommand`, `ill-formed control message`, or nothing at all. reportError now spells an error's name as words, and the refusals name their accepted forms: pty/ctl lists its verbs, a flag file takes 1 or 0, a setting word takes on or off, Del takes k, j or nothing, Repl takes - or a language. Kill with nothing to stop says so, /focus says pane, a Look that found nothing says no match, and pty/run on a command pane says it is not a shell. A ctl write's failure has room for the Repl list and is cut between words, the Repl word at a character.

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

1 files changed, 4 insertions, 2 deletions

diff --git a/src/ninep/pane.zig b/src/ninep/pane.zig
index 77be80c6..d2b2a791 100644
--- a/src/ninep/pane.zig
+++ b/src/ninep/pane.zig
@@ -507,7 +507,7 @@ fn writeRange(req: Req, pane: *Pane, file: PaneFile) Reply {
 
 fn writeFlag(p: *Pardes, req: Req, pane: *Pane, file: PaneFile) Reply {
     const word = std.mem.trim(u8, req.data, " \t\r\n");
-    if (!std.mem.eql(u8, word, "1") and !std.mem.eql(u8, word, "0")) return Reply.fail(req.tag, E.INVAL);
+    if (!std.mem.eql(u8, word, "1") and !std.mem.eql(u8, word, "0")) return tree.failText(req.tag, E.INVAL, "takes 1 or 0");
     const on = word[0] == '1';
     const pf = &pane.fs;
     switch (file) {
@@ -873,8 +873,10 @@ test "the flag files read and write the state acme kept behind ctl verbs" {
 
     for ([_]u64{ dirty, mark, scroll }) |node| {
         try testing.expectEqual(@as(u64, 2), call(p, .{ .tag = 1, .op = .getattr, .node = node }).reply.attr.size);
-        for ([_][]const u8{ "", "yes", "2", "0 1", "true" }) |bad|
+        for ([_][]const u8{ "", "yes", "2", "0 1", "true" }) |bad| {
             try testing.expectEqual(E.INVAL, wr(p, node, bad).errno());
+            try testing.expectEqualStrings("takes 1 or 0", wr(p, node, bad).reply.ename);
+        }
     }
 
     try testing.expectEqualStrings("0\n", rd(p, dirty, 0, 8).bytes);