Fix Ctrl+C signal handling and cross-server session compatibility

- Added proper PTY slave terminal configuration for signal interpretation
- Enabled ISIG flag so Ctrl+C generates SIGINT instead of being treated as text
- Configured ICANON and ECHO flags for proper terminal behavior
- Applied configuration in both child process code paths (manual dup2 and login_tty)

- Implemented hybrid proxy fallback system for cross-server session input
- Rust server now proxies input to Node.js server when pipe write fails
- Added reqwest HTTP client for seamless communication between servers
- Reduced pipe timeout to 1 second for faster fallback detection
- Added key translation for special keys when proxying to Node.js

This fixes both:
1. Ctrl+C not interrupting processes in Rust-created sessions
2. "Device not configured" errors when accessing Node.js sessions from Rust server

🤖 Generated with [Claude Code](https://claude.ai/code)

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

tty-fwd/Cargo.toml

@@ -35,6 +35,7 @@ ctrlc = "3.4.7"
 data-encoding = "2.9"
 glob = "0.3"
 notify = "8.0"
+reqwest = { version = "0.12", features = ["json", "blocking"] }
 
 [target.'cfg(windows)'.dependencies]
 windows-sys = { version = "0.60", features = ["Win32_System_Console"] }

tty-fwd/src/sessions.rs

@@ -164,10 +164,15 @@ pub fn send_key_to_session(
         _ => return Err(anyhow!("Unknown key: {}", key)),
     };
 
-    // Use a timeout-protected write operation that also checks for readers
+    // Try to write to the pipe directly first
-    write_to_pipe_with_timeout(&stdin_path, key_bytes, Duration::from_secs(5))?;
+    match write_to_pipe_with_timeout(&stdin_path, key_bytes, Duration::from_secs(1)) {
-
+        Ok(()) => Ok(()),
-    Ok(())
+        Err(pipe_error) => {
+            // If pipe write fails, try to proxy to Node.js server
+            eprintln!("Direct pipe write failed: {}, trying Node.js proxy for key", pipe_error);
+            proxy_key_to_nodejs_server(session_id, key)
+        }
+    }
 }
 
 pub fn send_text_to_session(
@@ -182,10 +187,56 @@ pub fn send_text_to_session(
         return Err(anyhow!("Session {} not found or not running", session_id));
     }
 
-    // Use a timeout-protected write operation that also checks for readers
+    // Try to write to the pipe directly first
-    write_to_pipe_with_timeout(&stdin_path, text.as_bytes(), Duration::from_secs(5))?;
+    match write_to_pipe_with_timeout(&stdin_path, text.as_bytes(), Duration::from_secs(1)) {
+        Ok(()) => Ok(()),
+        Err(pipe_error) => {
+            // If pipe write fails, try to proxy to Node.js server
+            eprintln!("Direct pipe write failed: {}, trying Node.js proxy", pipe_error);
+            proxy_input_to_nodejs_server(session_id, text)
+        }
+    }
+}
 
-    Ok(())
+fn proxy_input_to_nodejs_server(session_id: &str, text: &str) -> Result<(), anyhow::Error> {
+    use std::collections::HashMap;
+    
+    // Create HTTP client
+    let client = reqwest::blocking::Client::new();
+    
+    // Create request body
+    let mut body = HashMap::new();
+    body.insert("text", text);
+    
+    // Send request to Node.js server
+    let url = format!("http://localhost:3000/api/sessions/{}/input", session_id);
+    let response = client
+        .post(&url)
+        .json(&body)
+        .send()
+        .map_err(|e| anyhow!("Failed to proxy to Node.js server: {}", e))?;
+    
+    if response.status().is_success() {
+        Ok(())
+    } else {
+        Err(anyhow!("Node.js server returned error: {}", response.status()))
+    }
+}
+
+fn proxy_key_to_nodejs_server(session_id: &str, key: &str) -> Result<(), anyhow::Error> {
+    // Convert key to equivalent text sequence for Node.js server
+    let text = match key {
+        "arrow_up" => "\x1b[A",
+        "arrow_down" => "\x1b[B", 
+        "arrow_right" => "\x1b[C",
+        "arrow_left" => "\x1b[D",
+        "escape" => "\x1b",
+        "enter" | "ctrl_enter" => "\r",
+        "shift_enter" => "\x1b\x0d",
+        _ => return Err(anyhow!("Unknown key for proxy: {}", key)),
+    };
+    
+    proxy_input_to_nodejs_server(session_id, text)
 }
 
 fn write_to_pipe_with_timeout(

tty-fwd/src/tty_spawn.rs

@@ -711,6 +711,18 @@ fn spawn(mut opts: SpawnOptions) -> Result<i32, Error> {
         dup2(&slave_owned_fd, &mut stdout_fd).expect("Failed to dup2 stdout");
         dup2(&slave_owned_fd, &mut stderr_fd).expect("Failed to dup2 stderr");
 
+        // Configure the PTY slave for proper signal handling
+        if let Ok(mut attrs) = tcgetattr(&slave_owned_fd) {
+            // Enable signal interpretation (ISIG) so Ctrl+C generates SIGINT
+            attrs.local_flags.insert(LocalFlags::ISIG);
+            // Enable canonical mode for line editing but keep other flags
+            attrs.local_flags.insert(LocalFlags::ICANON);
+            // Keep echo enabled for interactive sessions
+            attrs.local_flags.insert(LocalFlags::ECHO);
+            // Apply the terminal attributes
+            tcsetattr(&slave_owned_fd, SetArg::TCSANOW, &attrs).ok();
+        }
+
         // Forget the OwnedFd instances to prevent them from being closed
         std::mem::forget(stdin_fd);
         std::mem::forget(stdout_fd);
@@ -723,7 +735,24 @@ fn spawn(mut opts: SpawnOptions) -> Result<i32, Error> {
         }
     } else {
         unsafe {
+            let _slave_fd = pty.slave.as_raw_fd();
             login_tty_compat(pty.slave.into_raw_fd())?;
+            
+            // Configure the PTY slave for proper signal handling after login_tty
+            use std::os::fd::{FromRawFd, OwnedFd};
+            let stdin_fd = OwnedFd::from_raw_fd(0); // stdin is now the slave
+            if let Ok(mut attrs) = tcgetattr(&stdin_fd) {
+                // Enable signal interpretation (ISIG) so Ctrl+C generates SIGINT
+                attrs.local_flags.insert(LocalFlags::ISIG);
+                // Enable canonical mode for line editing
+                attrs.local_flags.insert(LocalFlags::ICANON);
+                // Keep echo enabled for interactive sessions
+                attrs.local_flags.insert(LocalFlags::ECHO);
+                // Apply the terminal attributes
+                tcsetattr(&stdin_fd, SetArg::TCSANOW, &attrs).ok();
+            }
+            std::mem::forget(stdin_fd); // Don't close stdin
+            
             // No stderr redirection since script_mode is always false
         }
     }