fix: restore interactive PTY behavior

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a03397-4d51-7fd1-8ff2-946eb22ea2bc

src/tamq/ptytap.py

@@ -1,10 +1,13 @@
 from __future__ import annotations
 
+import fcntl
 import os
 import pty
 import select
 import signal
 import sys
+import termios
+import tty
 from collections.abc import Callable, Sequence
 
 from .broker import InputBroker
@@ -18,14 +21,70 @@ class PtyTap:
         self.broker = broker
         self.on_line = on_line
 
+    def _observe_input(self, buffer: bytearray, data: bytes) -> None:
+        buffer.extend(data)
+        while True:
+            delimiters = [index for marker in (b"\r", b"\n") if (index := buffer.find(marker)) >= 0]
+            if not delimiters:
+                return
+            index = min(delimiters)
+            raw = bytes(buffer[:index])
+            del buffer[: index + 1]
+            line = raw.decode("utf-8", errors="replace")
+            routed = self.broker.inspect_line(line)
+            if routed and self.on_line:
+                self.on_line(line)
+
     def run(self) -> int:
-        pid, master = pty.fork()
+        stdin_fd = sys.stdin.fileno()
+        stdout_fd = sys.stdout.fileno()
+        master, slave = pty.openpty()
+        copy_winsize(stdin_fd, slave)
+        pid = os.fork()
         if pid == 0:
-            os.execvp(self.command[0], self.command)
+            try:
+                os.close(master)
+                os.setsid()
+                fcntl.ioctl(slave, termios.TIOCSCTTY, 0)
+                for fd in (0, 1, 2):
+                    os.dup2(slave, fd)
+                if slave > 2:
+                    os.close(slave)
+                os.execvp(self.command[0], self.command)
+            except BaseException as exc:
+                os.write(2, f"tamq tap: cannot start {self.command[0]}: {exc}\n".encode())
+                os._exit(127)
+        os.close(slave)
         input_buffer = bytearray()
+        saved_terminal = termios.tcgetattr(stdin_fd) if os.isatty(stdin_fd) else None
+        saved_handlers: dict[int, signal.Handlers] = {}
+        input_open = True
+
+        def resize(_signum=None, _frame=None) -> None:
+            copy_winsize(stdin_fd, master)
+
+        def forward(signum, _frame) -> None:
+            try:
+                os.killpg(pid, signum)
+            except ProcessLookupError:
+                pass
+
+        status = 0
         try:
+            if saved_terminal is not None:
+                tty.setraw(stdin_fd)
+            saved_handlers[signal.SIGWINCH] = signal.signal(signal.SIGWINCH, resize)
+            for signum in (signal.SIGINT, signal.SIGTERM, signal.SIGHUP):
+                saved_handlers[signum] = signal.signal(signum, forward)
+            resize()
             while True:
-                readable, _, _ = select.select([master, sys.stdin], [], [])
+                sources = [master]
+                if input_open:
+                    sources.append(stdin_fd)
+                try:
+                    readable, _, _ = select.select(sources, [], [])
+                except InterruptedError:
+                    continue
                 if master in readable:
                     try:
                         data = os.read(master, 65536)
@@ -33,23 +92,51 @@ class PtyTap:
                         break
                     if not data:
                         break
-                    os.write(sys.stdout.fileno(), data)
-                if sys.stdin in readable:
-                    data = os.read(sys.stdin.fileno(), 65536)
+                    write_all(stdout_fd, data)
+                if input_open and stdin_fd in readable:
+                    data = os.read(stdin_fd, 65536)
                     if not data:
-                        break
-                    os.write(master, data)
-                    input_buffer.extend(data)
-                    while b"\n" in input_buffer:
-                        raw, _, rest = input_buffer.partition(b"\n")
-                        input_buffer = bytearray(rest)
-                        line = raw.decode("utf-8", errors="replace")
-                        routed = self.broker.inspect_line(line)
-                        if routed and self.on_line:
-                            self.on_line(line)
+                        input_open = False
+                        try:
+                            os.killpg(pid, signal.SIGHUP)
+                        except ProcessLookupError:
+                            pass
+                        continue
+                    write_all(master, data)
+                    self._observe_input(input_buffer, data)
+        except BaseException:
+            try:
+                os.killpg(pid, signal.SIGHUP)
+            except ProcessLookupError:
+                pass
+            raise
         finally:
+            for signum, handler in saved_handlers.items():
+                signal.signal(signum, handler)
+            if saved_terminal is not None:
+                termios.tcsetattr(stdin_fd, termios.TCSAFLUSH, saved_terminal)
+            os.close(master)
             try:
                 _, status = os.waitpid(pid, 0)
-                return os.waitstatus_to_exitcode(status)
             except ChildProcessError:
-                return 0
+                status = 0
+        return os.waitstatus_to_exitcode(status)
+
+
+def copy_winsize(source_fd: int, target_fd: int) -> bool:
+    """Copy terminal rows/columns and pixel dimensions when a source tty exists."""
+    try:
+        size = fcntl.ioctl(source_fd, termios.TIOCGWINSZ, b"\0" * 8)
+        fcntl.ioctl(target_fd, termios.TIOCSWINSZ, size)
+        return True
+    except OSError:
+        return False
+
+
+def write_all(fd: int, data: bytes) -> None:
+    view = memoryview(data)
+    while view:
+        written = os.write(fd, view)
+        if written == 0:
+            raise OSError("terminal write returned zero bytes")
+        view = view[written:]