# cloud9 integration

The published `cloud9` package owns the base 9P2000 wire format, client and server
connections, and TCP/Unix/QUIC transports. `build.zig.zon` pins a commit from
`git@git.sr.ht:~gbrls/cloud9`, so `zig build` fetches it into `zig-pkg/` like every
other dependency; no sibling checkout is required. Re-pin with
`zig fetch --save=cloud9 git+https://git.sr.ht/~gbrls/cloud9#<commit>`, and swap in
`.cloud9 = .{ .path = "../cloud9" }` while editing both packages at once.

The file-server engine (fids, jobs, parking, flush, hangup) is cloud9's
`fs.Server`; the control tree in `src/ninep/` is its backend, using cloud9's
`fs.Req`, `fs.Op`, `fs.Status`, `fs.E` and `fs.ReplyWith` (extended with the
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. 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.

Run `zig build 9p-test` for the engine configurations and
`zig build 9p-io-test -Dquic=true` for native transport/client integration. Run cloud9's `zig build test`,
`transport-test`, `quic-test -Dquic=true`, `fuzz`, and `differential` steps for the
shared implementation. See cloud9's `docs/validation.md` for recorded runs and
known test-environment limits.

Invalid framing now terminates a server connection. Cloud9 also checks reply
counts and reserves tags until flush completion. Client metadata is slightly
larger to track those reservations, and its bounds tests reflect that fixed cost.