Keep what each open holds in one table of open records

Snapshots (and /log's cursor), runs, and the reader_handle constants for
event and pty/data each reused the open handle and each validated
handle and node on its own. Now p.fs.opens is one table of 64 records,
each the node it was opened on and a tagged union of what it holds, like
lib9p's per-fid aux and acme's Fid (editors/acme/dat.h:373-385): one
lookup (openOf), one release, ENFILE when full. A held read lives in
its open's record, so it goes with the release. Opens that hold nothing
answer handle 0 and take no record.

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

1 files changed, 5 insertions, 2 deletions

diff --git a/src/ninep/pane.zig b/src/ninep/pane.zig
index b07ee038..c03cd776 100644
--- a/src/ninep/pane.zig
+++ b/src/ninep/pane.zig
@@ -32,6 +32,7 @@ pub const State = struct {
     /// `cat addr` answer what was written.
     addr: Range = .{},
     limit: ?Range = null,
+    /// Opens of `event`, which hold the pane scripted.
     readers: u16 = 0,
     /// One of `readers` reads `event`; a second reading open is refused.
     event_reader: bool = false,
@@ -39,9 +40,11 @@ pub const State = struct {
     nomark: bool = false,
     noscroll: bool = false,
     tag_snap: std.ArrayList(u8) = .empty,
-    pty_readers: u16 = 0,
+    /// An open reads pty/data, so output queues for it; a second is refused.
+    pty_reader: bool = false,
     pty_out: events.Queue = .{},
-    /// The pty/run open waiting on this shell's current command.
+    /// The open record (tree.zig) of the pty/run waiting on this shell's
+    /// current command.
     run: ?u8 = null,
     /// The host started a shell it could not teach to mark its prompts.
     unmarked: bool = false,