core/cli: pause turn cancel during TTY confirm prompts

Max-rounds and destructive-tool confirms no longer cancel the in-flight
turn; SIGINT during the prompt aborts only the confirm.

src/plyngent/cli/interrupt.py

@@ -0,0 +1,58 @@
+from __future__ import annotations
+
+import contextlib
+import signal
+from contextlib import contextmanager
+from contextvars import ContextVar
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from collections.abc import Callable, Generator
+    from types import FrameType
+
+    type SigHandler = Callable[[int, FrameType | None], None] | int | None
+
+_allow_task_cancel: ContextVar[bool] = ContextVar("allow_task_cancel", default=True)
+_reinstall_holder: list[Callable[[], None] | None] = [None]
+
+
+def allow_task_cancel() -> bool:
+    """Whether the CLI SIGINT handler should cancel the in-flight turn task."""
+    return _allow_task_cancel.get()
+
+
+def set_sigint_reinstall(callback: Callable[[], None] | None) -> None:
+    """Register how to re-bind SIGINT after a TTY prompt (set by run_cancellable)."""
+    _reinstall_holder[0] = callback
+
+
+@contextmanager
+def pause_task_cancel_for_prompt() -> Generator[None]:
+    """Disable turn-task cancel during blocking TTY prompts (confirm, etc.).
+
+    Also restores the default SIGINT handler so ``click.confirm`` can receive
+    KeyboardInterrupt / Abort instead of the asyncio turn being cancelled.
+    """
+    token = _allow_task_cancel.set(False)
+    loop_handler_removed = False
+    previous: SigHandler = signal.SIG_DFL
+    try:
+        try:
+            import asyncio
+
+            loop = asyncio.get_running_loop()
+            _ = loop.remove_signal_handler(signal.SIGINT)
+            loop_handler_removed = True
+        except (RuntimeError, NotImplementedError, ValueError):
+            loop_handler_removed = False
+
+        previous = signal.getsignal(signal.SIGINT)
+        _ = signal.signal(signal.SIGINT, signal.default_int_handler)
+        yield
+    finally:
+        _ = signal.signal(signal.SIGINT, previous)  # type: ignore[arg-type]
+        reinstall = _reinstall_holder[0]
+        if loop_handler_removed and reinstall is not None:
+            with contextlib.suppress(RuntimeError, NotImplementedError, ValueError):
+                reinstall()
+        _allow_task_cancel.reset(token)

src/plyngent/cli/limits.py

@@ -4,6 +4,7 @@ from typing import TYPE_CHECKING
 
 import click
 
+from plyngent.cli.interrupt import pause_task_cancel_for_prompt
 from plyngent.tools.process.pty_session import PtyManager
 
 if TYPE_CHECKING:
@@ -14,10 +15,11 @@ def prompt_continue_limit(reason: str) -> bool:
     """Ask the user whether to raise a limit and continue (TTY)."""
     click.echo()
     click.secho(f"[limit] {reason}", fg="yellow")
-    try:
-        return bool(click.confirm("Raise limit and continue?", default=True))
-    except click.Abort:
-        return False
+    with pause_task_cancel_for_prompt():
+        try:
+            return bool(click.confirm("Raise limit and continue?", default=True))
+        except (click.Abort, KeyboardInterrupt):
+            return False
 
 
 def prompt_confirm_tool(name: str, args: Mapping[str, object], reason: str) -> bool:
@@ -25,10 +27,11 @@ def prompt_confirm_tool(name: str, args: Mapping[str, object], reason: str) -> b
     del args
     click.echo()
     click.secho(f"[confirm] tool {name!r}: {reason}", fg="yellow")
-    try:
-        return bool(click.confirm("Allow this tool call?", default=False))
-    except click.Abort:
-        return False
+    with pause_task_cancel_for_prompt():
+        try:
+            return bool(click.confirm("Allow this tool call?", default=False))
+        except (click.Abort, KeyboardInterrupt):
+            return False
 
 
 def install_cli_limit_hooks() -> None:

src/plyngent/cli/retry.py

@@ -9,6 +9,7 @@ from typing import TYPE_CHECKING
 import click
 
 from plyngent.cli.display import render_events
+from plyngent.cli.interrupt import allow_task_cancel, set_sigint_reinstall
 
 if TYPE_CHECKING:
     from collections.abc import AsyncIterator, Callable, Coroutine
@@ -39,20 +40,30 @@ async def sleep_cancellable(seconds: float) -> bool:
 async def run_cancellable[T](coro: Coroutine[object, object, T]) -> T:
     """Await ``coro`` as a task; Ctrl+C / SIGINT cancels the task.
 
+    Interactive prompts (max-rounds / destructive confirm) temporarily disable
+    task cancel so the user can answer instead of aborting the whole turn.
+
     Raises:
         asyncio.CancelledError: If the task was cancelled (including via SIGINT).
     """
-    task = asyncio.create_task(coro)
+    task: asyncio.Task[T] = asyncio.create_task(coro)
     loop = asyncio.get_running_loop()
     installed = False
 
     def _on_sigint() -> None:
-        if not task.done():
+        if allow_task_cancel() and not task.done():
             _ = task.cancel()
 
+    def _reinstall() -> None:
+        try:
+            loop.add_signal_handler(signal.SIGINT, _on_sigint)
+        except (NotImplementedError, RuntimeError, ValueError):
+            return
+
     try:
         loop.add_signal_handler(signal.SIGINT, _on_sigint)
         installed = True
+        set_sigint_reinstall(_reinstall)
     except (NotImplementedError, RuntimeError, ValueError):
         installed = False
 
@@ -65,6 +76,7 @@ async def run_cancellable[T](coro: Coroutine[object, object, T]) -> T:
                 await task
         raise asyncio.CancelledError from None
     finally:
+        set_sigint_reinstall(None)
         if installed:
             _ = loop.remove_signal_handler(signal.SIGINT)
         if not task.done():