Remove unused --nc flag and nc crate (#55962)

The `nc` crate and `zed --nc <socket>` flag were added in #34577 to let
the Claude Code integration spawn the running zed binary as a
netcat-style bridge between stdio and a Unix socket for its MCP server.

That integration was removed in #37120 in favor of the external
`@agentclientprotocol/claude-agent-acp` npm package, which dropped the
only caller of `--nc`. The flag, its dispatch in `main.rs`, and the `nc`
crate itself were left behind and have been unused since.

Nothing in the Zed codebase spawns `zed --nc` anymore, so remove the
flag and delete the crate. The unrelated `--askpass` netcat bridge (in
the `askpass` crate) is unaffected.

Release Notes:

- N/A

.github/CODEOWNERS.hold

@@ -181,7 +181,6 @@
 /crates/fs_benchmarks/ @zed-industries/infrastructure-team
 /crates/http_client/ @zed-industries/infrastructure-team
 /crates/http_client_tls/ @zed-industries/infrastructure-team
-/crates/nc/ @zed-industries/infrastructure-team
 /crates/net/ @zed-industries/infrastructure-team
 /crates/paths/ @zed-industries/infrastructure-team
 /crates/release_channel/ @zed-industries/infrastructure-team

Cargo.lock

@@ -11725,16 +11725,6 @@ dependencies = [
  "uuid",
 ]
 
-[[package]]
-name = "nc"
-version = "0.1.0"
-dependencies = [
- "anyhow",
- "futures 0.3.32",
- "net",
- "smol",
-]
-
 [[package]]
 name = "ndk"
 version = "0.9.0"
@@ -23598,7 +23588,6 @@ dependencies = [
  "migrator",
  "mimalloc",
  "miniprofiler_ui",
- "nc",
  "node_runtime",
  "notifications",
  "onboarding",

Cargo.toml

@@ -137,7 +137,6 @@ members = [
     "crates/miniprofiler_ui",
     "crates/mistral",
     "crates/multi_buffer",
-    "crates/nc",
     "crates/net",
     "crates/node_runtime",
     "crates/notifications",
@@ -399,7 +398,6 @@ migrator = { path = "crates/migrator" }
 mistral = { path = "crates/mistral" }
 multi_buffer = { path = "crates/multi_buffer" }
 miniprofiler_ui = { path = "crates/miniprofiler_ui" }
-nc = { path = "crates/nc" }
 net = { path = "crates/net" }
 node_runtime = { path = "crates/node_runtime" }
 notifications = { path = "crates/notifications" }

crates/nc/Cargo.toml

@@ -1,19 +0,0 @@
-[package]
-name = "nc"
-version = "0.1.0"
-edition.workspace = true
-publish.workspace = true
-license = "GPL-3.0-or-later"
-
-[lints]
-workspace = true
-
-[lib]
-path = "src/nc.rs"
-doctest = false
-
-[dependencies]
-anyhow.workspace = true
-futures.workspace = true
-net.workspace = true
-smol.workspace = true

crates/nc/LICENSE-GPL

@@ -1 +0,0 @@
-../../LICENSE-GPL

crates/nc/src/nc.rs

@@ -1,51 +0,0 @@
-use anyhow::Result;
-
-#[cfg(windows)]
-pub fn main(_socket: &str) -> Result<()> {
-    // It looks like we can't get an async stdio stream on Windows from smol.
-    panic!("--nc isn't yet supported on Windows");
-}
-
-/// The main function for when Zed is running in netcat mode
-#[cfg(not(windows))]
-pub fn main(socket: &str) -> Result<()> {
-    use futures::{AsyncReadExt as _, AsyncWriteExt as _, FutureExt as _, io::BufReader, select};
-    use net::async_net::UnixStream;
-    use smol::{Unblock, io::AsyncBufReadExt};
-
-    smol::block_on(async {
-        let socket_stream = UnixStream::connect(socket).await?;
-        let (socket_read, mut socket_write) = socket_stream.split();
-        let mut socket_reader = BufReader::new(socket_read);
-
-        let mut stdout = Unblock::new(std::io::stdout());
-        let stdin = Unblock::new(std::io::stdin());
-        let mut stdin_reader = BufReader::new(stdin);
-
-        let mut socket_line = Vec::new();
-        let mut stdin_line = Vec::new();
-
-        loop {
-            select! {
-                bytes_read = socket_reader.read_until(b'\n', &mut socket_line).fuse() => {
-                    if bytes_read? == 0 {
-                        break
-                    }
-                    stdout.write_all(&socket_line).await?;
-                    stdout.flush().await?;
-                    socket_line.clear();
-                }
-                bytes_read = stdin_reader.read_until(b'\n', &mut stdin_line).fuse() => {
-                    if bytes_read? == 0 {
-                        break
-                    }
-                    socket_write.write_all(&stdin_line).await?;
-                    socket_write.flush().await?;
-                    stdin_line.clear();
-                }
-            }
-        }
-
-        anyhow::Ok(())
-    })
-}

crates/zed/Cargo.toml

@@ -156,7 +156,6 @@ menu.workspace = true
 migrator.workspace = true
 miniprofiler_ui.workspace = true
 mimalloc = { version = "0.1", optional = true }
-nc.workspace = true
 node_runtime.workspace = true
 notifications.workspace = true
 onboarding.workspace = true

crates/zed/src/main.rs

@@ -244,17 +244,6 @@ fn main() {
         return;
     }
 
-    // `zed --nc` Makes zed operate in nc/netcat mode for use with MCP
-    if let Some(socket) = &args.nc {
-        match nc::main(socket) {
-            Ok(()) => return,
-            Err(err) => {
-                eprintln!("Error: {}", err);
-                process::exit(1);
-            }
-        }
-    }
-
     #[cfg(all(not(debug_assertions), target_os = "windows"))]
     unsafe {
         use windows::Win32::System::Console::{ATTACH_PARENT_PROCESS, AttachConsole};
@@ -1831,11 +1820,6 @@ struct Args {
     #[arg(long)]
     system_specs: bool,
 
-    /// Used for the MCP Server, to remove the need for netcat as a dependency,
-    /// by having Zed act like netcat communicating over a Unix socket.
-    #[arg(long, hide = true)]
-    nc: Option<String>,
-
     /// Used for recording minidumps on crashes by having Zed run a separate
     /// process communicating over a socket.
     #[arg(long, hide = true)]