fix(vite_pty): drop slave after spawn to signal EOF on child exit

Drop the PTY slave handle immediately after spawning the child process.
This ensures EOF is signaled on the reader when the child exits, which
is critical for the zig linker builds where the slave handle was keeping
the PTY open.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: branchseer

crates/vite_pty/src/terminal.rs

@@ -5,13 +5,13 @@ use std::{
 };
 
 pub use portable_pty::CommandBuilder;
-use portable_pty::{ChildKiller, ExitStatus, PtyPair};
+use portable_pty::{ChildKiller, ExitStatus, MasterPty};
 
 use crate::geo::ScreenSize;
 
 /// A headless terminal
 pub struct Terminal {
-    pty_pair: PtyPair,
+    master: Box<dyn MasterPty + Send>,
     parser: vt100::Parser<Vt100Callbacks>,
     child_killer: Box<dyn ChildKiller + Send + Sync>,
     reader: Box<dyn Read + Send>,
@@ -72,10 +72,13 @@ impl Terminal {
         })?;
         // Create reader BEFORE spawning child to ensure it's ready for data
         let reader = pty_pair.master.try_clone_reader()?;
-        let mut child = pty_pair.slave.spawn_command(cmd)?;
-        let child_killer = child.clone_killer();
         let writer: Arc<Mutex<Option<Box<dyn Write + Send>>>> =
             Arc::new(Mutex::new(Some(pty_pair.master.take_writer()?)));
+        // Spawn child and immediately drop slave to ensure EOF is signaled when child exits
+        let mut child = pty_pair.slave.spawn_command(cmd)?;
+        let child_killer = child.clone_killer();
+        drop(pty_pair.slave); // Critical: drop slave so EOF is signaled when child exits
+        let master = pty_pair.master;
         let exit_status: Arc<OnceLock<ExitStatus>> = Arc::new(OnceLock::new());
 
         // Background thread: wait for child to exit, set exit status, then close writer to trigger EOF
@@ -93,7 +96,7 @@ impl Terminal {
         });
 
         Ok(Self {
-            pty_pair,
+            master,
             parser: vt100::Parser::new_with_callbacks(
                 size.rows,
                 size.cols,
@@ -266,7 +269,7 @@ impl Terminal {
     /// Returns an error if the PTY cannot be resized.
     pub fn resize(&mut self, size: ScreenSize) -> anyhow::Result<()> {
         // Resize the underlying PTY via portable-pty's MasterPty::resize
-        self.pty_pair.master.resize(portable_pty::PtySize {
+        self.master.resize(portable_pty::PtySize {
             rows: size.rows,
             cols: size.cols,
             pixel_width: 0,