9proc core becomes a backend of cloud9.fs; engine gains optional features

9proc's own fid table, walk loop and dir-read engine are replaced by
cloud9.fs.Server; the tree (static, vars, providers) is served through the
engine's Req/Reply contract with node ids that keep the old qid scheme.
Providers may answer later by returning error.Again (parked in the engine,
retried each step, Tflush -> EINTR); no new files are exposed.
Engine (backward compatible, all opt-in via Backend.features / Options):
create, remove, wstat, reference accounting for backends that count
handles, a salted fid index, name_capacity 0 (names from getattr),
Reply.ename for backend-chosen error text, Attr.path/version/atime.
Engine-level error strings and the 217-byte msize floor now apply to 9proc;
tests updated accordingly.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

1 files changed, 1 insertions, 1 deletions

diff --git a/9proc/src/linux/probe.zig b/9proc/src/linux/probe.zig
index 559d981..4db277d 100644
--- a/9proc/src/linux/probe.zig
+++ b/9proc/src/linux/probe.zig
@@ -427,7 +427,7 @@ pub fn Probe(comptime Srv: type) type {
         /// Free space in the connection's input buffer (cloud9 keeps one
         /// msize-sized frame; `push` copies at most this much).
         fn inputRoom(conn: *const Srv.Conn) usize {
-            return conn.server.in.len - conn.server.in_len;
+            return conn.inputRoom();
         }
 
         fn readClient(p: *Self, i: usize, hup: bool) void {