fix: Terminal escape sequence responses displayed on first prompt when starting tmux

Cargo.toml

@@ -43,6 +43,7 @@ regex = "1.12.2"
 lazy_static = "1.5"
 ctrlc = "3.5.1"
 signal-hook = "0.3.18"
+nix = { version = "0.29", features = ["poll"] }
 atty = "0.2.14"
 arrayvec = "0.7.6"
 smallvec = "1.15.1"

README.md

@@ -101,6 +101,14 @@ bssh -o StrictHostKeyChecking=no user@host
 bssh -Q cipher
 ```
 
+**PTY Session Escape Sequences:**
+
+Like OpenSSH, bssh supports escape sequences in PTY sessions. These must be typed at the beginning of a line (after pressing Enter):
+
+| Escape | Description |
+|--------|-------------|
+| `~.`   | Disconnect from the remote host |
+
 ### Port Forwarding
 ```bash
 # Local port forwarding (-L)

src/pty/session/constants.rs

@@ -13,28 +13,32 @@
 // limitations under the License.
 
 //! Terminal constants and key sequence definitions
+//!
+//! NOTE: Many key sequence constants are currently unused since we switched to
+//! raw byte passthrough (see issue #87), but are kept for reference and potential
+//! future debugging use.
+
+// Allow dead code for unused key sequence constants
+#![allow(dead_code)]
 
 // Buffer size constants for allocation optimization
 // These values are chosen based on empirical testing and SSH protocol characteristics
 
 /// Maximum size for terminal key sequences (ANSI escape sequences are typically 3-7 bytes)
 /// Value: 8 bytes - Accommodates the longest standard ANSI sequences (F-keys: ESC[2x~)
 /// Rationale: Most key sequences are 1-5 bytes, 8 provides safe headroom without waste
-#[allow(dead_code)]
 pub const MAX_KEY_SEQUENCE_SIZE: usize = 8;
 
 /// Buffer size for SSH I/O operations (4KB aligns with typical SSH packet sizes)
 /// Value: 4096 bytes - Matches common SSH packet fragmentation boundaries
 /// Rationale: SSH protocol commonly uses 4KB packets; larger buffers reduce syscalls
 /// but increase memory usage. 4KB provides optimal balance for interactive sessions.
-#[allow(dead_code)]
 pub const SSH_IO_BUFFER_SIZE: usize = 4096;
 
 /// Maximum size for terminal output chunks processed at once
 /// Value: 1024 bytes - Balance between responsiveness and efficiency
 /// Rationale: Smaller chunks improve perceived responsiveness for interactive use,
 /// while still being large enough to batch terminal escape sequences efficiently.
-#[allow(dead_code)]
 pub const TERMINAL_OUTPUT_CHUNK_SIZE: usize = 1024;
 
 /// PTY message channel sizing:
@@ -57,7 +61,7 @@ pub const INPUT_POLL_TIMEOUT_MS: u64 = 500;
 /// - Tasks should check cancellation signal frequently (10-50ms intervals)
 pub const TASK_CLEANUP_TIMEOUT_MS: u64 = 100;
 
-// Const arrays for frequently used key sequences to avoid repeated allocations
+// Const arrays for frequently used key sequences to avoid repeated allocations.
 /// Control key sequences - frequently used in terminal input
 pub const CTRL_C_SEQUENCE: &[u8] = &[0x03]; // Ctrl+C (SIGINT)
 pub const CTRL_D_SEQUENCE: &[u8] = &[0x04]; // Ctrl+D (EOF)