A command line cut across writes runs once whole, and look/exec answer per open

A mount cuts a write at its message size, and each piece ran on its own: a
line cut at the boundary ran as shell commands and a 50 KB Edit block
broke. An open of look, exec, tagexec, any ctl or a column's exec now keeps
an unfinished last line, or an Edit block still open, until its next write
or its release, and never runs a fragment. The same open record holds what
its last write touched, which a read on it answers (as /net/tcp/clone
does); an open that never wrote reads the session's last as of its open.
A release that runs a held line waits for quiet and counts as a change;
a clicked line with a control character is still refused at its write.
Tested in unit tests, fs.py (python client, 8 KiB) and selfmount.py (the
kernel mount, a 1000-line seq burst and a 50 KB Edit block).

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

1 files changed, 4 insertions, 2 deletions

diff --git a/src/9p_io.zig b/src/9p_io.zig
index 0f5e0a77..72963e08 100644
--- a/src/9p_io.zig
+++ b/src/9p_io.zig
@@ -255,7 +255,7 @@ pub const Listener = struct {
             const refused = pardes.ctlfs.Reply.fail(req.tag, pardes.ctlfs.E.IO);
             return conn.reply(&refused, "");
         }
-        if (!quiet and pardes.ctlfs.needsQuiet(req)) {
+        if (!quiet and pardes.ctlfs.needsQuiet(l.core, req)) {
             pardes.turn.parked = true;
             const later: pardes.ctlfs.Reply = .{ .tag = req.tag, .status = .again };
             return conn.reply(&later, "");
@@ -263,6 +263,8 @@ pub const Listener = struct {
         const core = l.core;
         const epoch = pardes.turn.epoch;
         const restores = pardes.turn.restores;
+        // Asked first: a release that runs a held line has none after.
+        const changes = pardes.ctlfs.changesPane(core, req);
         const reply = core.serveFs(req);
         if (req.op == .release and quiet) l.collectOs();
         // A read with nothing yet stays parked in the engine, and the core
@@ -289,7 +291,7 @@ pub const Listener = struct {
             o.held = .{ .asker = conn, .req = req, .ticket = ticket };
             return;
         }
-        if (!pardes.ctlfs.changesPane(req)) return conn.reply(&reply, core.fsPayload(reply));
+        if (!changes) return conn.reply(&reply, core.fsPayload(reply));
         // The editor draws the change and performs what it asked for; when
         // it asked for something -- a save, a shell, a watch -- the answer
         // waits until that is done, so `echo Save > exec` returns with the