From 56b54e269a611603c418af4daa31574d723986f4 Mon Sep 17 00:00:00 2001
From: Fusion <noreply@runfusion.ai>
Date: Thu, 21 May 2026 12:03:36 +0200
Subject: [PATCH] fix(terminal): create PTY for proper interactive shell

- Use Python pty module to create pseudo-terminal
- Pass slave fd to docker exec for real TTY allocation
- Fixes ioctl errors and job control warnings
- Supports terminal resizing via TIOCSWINSZ

Quality gates: local testing
---
 apps/api/src/services/terminal_session.py | 86 +++++++++++++++--------
 1 file changed, 55 insertions(+), 31 deletions(-)

diff --git a/apps/api/src/services/terminal_session.py b/apps/api/src/services/terminal_session.py
index adbbd79..4ee7af8 100644
--- a/apps/api/src/services/terminal_session.py
+++ b/apps/api/src/services/terminal_session.py
@@ -1,6 +1,11 @@
 """Terminal session management for tool instances."""
 
 import asyncio
+import os
+import pty
+import select
+import struct
+import fcntl
 import uuid
 from typing import Any
 
@@ -14,11 +19,19 @@ class TerminalSession:
         self.container_id = container_id
         self.process: asyncio.subprocess.Process | None = None
         self._closed = False
+        self._master_fd: int | None = None
+        self._slave_fd: int | None = None
 
     async def start(self) -> None:
-        """Start the docker exec process with a shell."""
-        # Use docker exec -it to allocate a proper TTY
-        # This gives bash a real terminal and avoids ioctl/job control errors
+        """Start the docker exec process with a shell using a PTY."""
+        # Create a pseudo-terminal on the host
+        self._master_fd, self._slave_fd = pty.openpty()
+        
+        # Set the terminal size initially
+        self._set_terminal_size(80, 24)
+        
+        # Start docker exec with the slave fd as stdin/stdout/stderr
+        # Using -it because the slave fd IS a TTY
         self.process = await asyncio.create_subprocess_exec(
             "docker",
             "exec",
@@ -28,50 +41,54 @@ class TerminalSession:
             self.container_id,
             "bash",
             "-il",
-            stdin=asyncio.subprocess.PIPE,
-            stdout=asyncio.subprocess.PIPE,
-            stderr=asyncio.subprocess.STDOUT,
+            stdin=self._slave_fd,
+            stdout=self._slave_fd,
+            stderr=self._slave_fd,
         )
+        
+        # Close slave fd in parent process
+        os.close(self._slave_fd)
+        self._slave_fd = None
+
+    def _set_terminal_size(self, cols: int, rows: int) -> None:
+        """Set the terminal size using TIOCSWINSZ."""
+        if self._master_fd is None:
+            return
+        # TIOCSWINSZ = 0x5414 on Linux
+        TIOCSWINSZ = 0x5414
+        size = struct.pack('HHHH', rows, cols, 0, 0)
+        try:
+            fcntl.ioctl(self._master_fd, TIOCSWINSZ, size)
+        except (OSError, IOError):
+            pass
 
     async def read_output(self) -> bytes:
-        """Read output from the process."""
-        if self.process is None or self.process.stdout is None:
+        """Read output from the PTY master."""
+        if self._master_fd is None or self._closed:
             return b""
         try:
-            return await self.process.stdout.read(4096)
-        except (asyncio.CancelledError, BrokenPipeError):
+            # Use select to check if data is available
+            readable, _, _ = select.select([self._master_fd], [], [], 0.1)
+            if readable:
+                return os.read(self._master_fd, 4096)
+            return b""
+        except (OSError, IOError, ValueError):
             return b""
 
     async def write_input(self, data: bytes) -> None:
-        """Write input to the process."""
-        if self.process is None or self.process.stdin is None or self._closed:
+        """Write input to the PTY master."""
+        if self._master_fd is None or self._closed:
             return
         try:
-            self.process.stdin.write(data)
-            await self.process.stdin.drain()
-        except (BrokenPipeError, ConnectionResetError):
+            os.write(self._master_fd, data)
+        except (OSError, IOError):
             pass
 
     async def resize(self, cols: int, rows: int) -> None:
         """Resize the terminal."""
         if self._closed:
             return
-        try:
-            proc = await asyncio.create_subprocess_exec(
-                "docker",
-                "exec",
-                self.container_id,
-                "stty",
-                "cols",
-                str(cols),
-                "rows",
-                str(rows),
-                stdout=asyncio.subprocess.DEVNULL,
-                stderr=asyncio.subprocess.DEVNULL,
-            )
-            await proc.wait()
-        except Exception:
-            pass
+        self._set_terminal_size(cols, rows)
 
     async def close(self) -> None:
         """Close the session and cleanup."""
@@ -79,6 +96,13 @@ class TerminalSession:
             return
         self._closed = True
 
+        if self._master_fd is not None:
+            try:
+                os.close(self._master_fd)
+            except OSError:
+                pass
+            self._master_fd = None
+
         if self.process is not None:
             try:
                 self.process.kill()