Record /log whether or not anyone reads it, with the editor's messages in it

/log is now one ring (64 KiB, 4 KiB on the board) that records new, del,
rename and save, and a msg line for everything the editor says. An open
freezes it, so cat log shows what happened lately and ends; writing
follow to that same open makes reads past it wait for newer records, and
a follower the ring outran reads lost N first.

The message log keeps the pane's serial, not its reusable slot.

A test now fails when the tree serves a file /README never mentions; it
caught pty/status, now documented along with typing through pty/data.

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

1 files changed, 6 insertions, 4 deletions

diff --git a/src/fs.zig b/src/fs.zig
index 84ab3b95..fef4ffe1 100644
--- a/src/fs.zig
+++ b/src/fs.zig
@@ -308,8 +308,10 @@ test "virtual writes enforce permissions even when contents are empty" {
     const p = try pardes.Pardes.init(std.testing.allocator, .{ .tty_only = true });
     defer p.deinit();
     for ([_][]const u8{ "", "bytes" }) |bytes| {
-        for ([_][]const u8{ "/virtual/index", "/virtual/screen", "/virtual/README", "/n/self/log" }) |path|
+        for ([_][]const u8{ "/virtual/index", "/virtual/screen", "/virtual/README" }) |path|
             try std.testing.expectError(error.ReadOnlyFilesystem, write(p, path, bytes));
+        // /log takes one word, `follow`, and only on the open it changes.
+        if (bytes.len > 0) if (write(p, "/n/self/log", bytes)) |_| return error.TestUnexpectedResult else |_| {};
         try std.testing.expectError(error.IsDirectory, write(p, "/virtual/pane", bytes));
         try std.testing.expectError(error.FileNotFound, write(p, "/virtual/missing", bytes));
         try std.testing.expectError(error.FileNotFound, write(p, "/virtual/cons", bytes));
@@ -1240,9 +1242,9 @@ pub const Namespace = struct {
     panes: [MAX_PANES]tree.pane.State = @splat(.{}),
     listeners: u16 = 0,
     origin: u8 = 'K',
-    /// The editor-wide event stream, recorded only while /log is held open.
-    log: tree.events.Queue = .{},
-    log_readers: u16 = 0,
+    /// The editor-wide event ring: panes made, renamed, saved and closed, and
+    /// what the editor said. Recorded whether or not anyone reads /log.
+    log: tree.events.Queue = .{ .cap = limits.log_bytes },
     /// What the last look or exec created or touched, answered by reading
     /// either of those files.
     results: [MAX_PANES]u32 = undefined,