Serve Unix and TCP 9P through cloud9.serve's std.Io runner

The hand-written poll loop for Unix/TCP listeners is replaced by
cloud9.serve.Runner; requests are queued to the editor thread, which answers
them under the connection lock on each frame and retries parked reads as
before. QUIC keeps the poll path (its adapter is fd based). The detached
server no longer loses a wake that lands between frames. The firmware path
keeps driving the engine with push/step. cloud9 re-pinned.

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

2 files changed, 15 insertions, 6 deletions

diff --git a/docs/cloud9.md b/docs/cloud9.md
index d31d2cb3..d5acc37c 100644
--- a/docs/cloud9.md
+++ b/docs/cloud9.md
@@ -13,8 +13,15 @@ The file-server engine (fids, jobs, parking, flush, hangup) is cloud9's
 editor's reply payload locator). `src/9p.zig` names the editor's and the
 board's `fs.Options` and re-exports the wire names the transports use.
 Mounting, Unix namespace discovery and permissions, the editor event loop,
-connection limits, and exported tree policy remain here. `src/9p_quic.zig`
-selects the existing `pardes-9p` ALPN for cloud9's optional OpenSSL transport.
+connection limits, and exported tree policy remain here. The Unix and TCP
+listeners run on cloud9's `serve.Runner` (`std.Io`: an accept task per
+listener, a reader and a writer task per connection, four slots); its handler
+queues every backend request for the editor's thread, which answers them all
+in `Listener.tick` after each editor update, retries parked reads there, and
+has the runner ship the replies. `src/9p_quic.zig` selects the existing
+`pardes-9p` ALPN for cloud9's optional OpenSSL transport; QUIC still runs on
+the poll loop in `src/9p_io.zig`, since cloud9's QUIC adapter is
+nonblocking-descriptor based rather than `std.Io` based.
 The standalone protocol/GPIO tests import the same module. The separate
 `05-zig-p4` build also supplies cloud9 for the GPIO firmware entry.
 
diff --git a/docs/fs.md b/docs/fs.md
index a9293393..55ffdc9c 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -40,8 +40,9 @@ IPv4/IPv6 addresses, not DNS names. Listener port zero chooses a free port;
 All connections have session access, including `os`. TCP is unencrypted.
 QUIC uses an ephemeral TLS identity without peer verification or login.
 It carries 9P2000 on one bidirectional stream with ALPN `pardes-9p`.
-The four application connection slots are shared across transports;
-OpenSSL's internal buffers are separate, dynamically allocated memory.
+Unix and TCP connections share four slots served by cloud9's `std.Io`
+runner; QUIC has four of its own on the editor's poll loop. OpenSSL's
+internal buffers are separate, dynamically allocated memory.
 
 [Plan9port's client](https://9fans.github.io/plan9port/man/man1/9p.html) can
 drive Unix or TCP without a kernel mount, and `9ns` mounts the tree in a
@@ -141,8 +142,9 @@ and the editor's reply payload over cloud9's backend contract), `pane.zig`
 (pane files), `ctl.zig`, `addr.zig`, `pty.zig`, `events.zig` (event and log
 streams), `screen.zig` and `sources.zig`. The protocol engine is cloud9's
 `fs.Server`, configured in `src/9p.zig` (the editor's and the board's
-capacities); the transports are `src/9p_io.zig`; `src/fs.zig` keeps host
-access, mounts, resolution, find and grep.
+capacities); the transports are `src/9p_io.zig` (cloud9's `serve.Runner`
+for Unix and TCP, a poll loop for QUIC, and the 9P client for mounts);
+`src/fs.zig` keeps host access, mounts, resolution, find and grep.
 
 `zig build fs-test` drives real sessions using the independent Python client
 in `test/ninep.py`; `zig build fs-discovery-test` checks that browsing creates