Fix misleading command.exit_code.native capability

README.md

@@ -317,7 +317,7 @@ Discovery reports backend and protocol capabilities such as:
 - `command.stdout.streaming`
 - `command.stderr.separate`
 - `command.events.streaming.best_effort`
-- `command.exit_code.native`
+- `command.exit_code`
 - `command.cancel.best_effort`
 - `shell.cmd.available`
 - `shell.bash.available`

src/liveshell/capabilities.py

@@ -22,7 +22,19 @@ def discover_capabilities() -> list[Capability]:
         Capability("command.async", True),
         Capability("command.poll", True),
         Capability("command.timeout", True),
-        Capability("command.exit_code.native", True),
+        Capability(
+            "command.exit_code",
+            True,
+            {
+                # cmd/bash surface the shell's real exit status ($?/%ERRORLEVEL%),
+                # but it is scraped from a stdout sentinel, not an OS-native process
+                # exit. Only hosted PowerShell reads it natively in-process
+                # ($LASTEXITCODE + HadErrors via the .NET runspace).
+                "cmd": "sentinel_parsed",
+                "bash": "sentinel_parsed",
+                "hosted_powershell": "native",
+            },
+        ),
         Capability(
             "daemon.protocol",
             True,

src/liveshell/daemon.py

@@ -632,6 +632,22 @@ def _run_command_worker(
             if self._is_terminal(command_id):
                 return
 
+            # Handle the case where cancel_command killed the process before the
+            # while loop above detected cancel_event.  The exec_thread may finish
+            # (process killed → non-zero exit) and exit the loop via
+            # exec_thread.is_alive() becoming False before cancel_event.is_set()
+            # is checked.  Without this guard the worker would call _finish_failed
+            # and win the race against _finish_canceled in cancel_command.
+            if cancel_event.is_set():
+                self._finish_canceled_if_active(
+                    command_id,
+                    reason="cancel_requested",
+                    session=session,
+                    termination_strategy="process_killed",
+                    close_session=True,
+                )
+                return
+
             error = result_holder.get("error")
             if error is not None:
                 error_text = str(error)

tests/test_capabilities.py

@@ -57,6 +57,21 @@ def test_daemon_protocol_advertises_both_transports(self) -> None:
         # There is still no remote/auto-started network server.
         self.assertFalse(details["remote_network"])
 
+    def test_exit_code_capability_distinguishes_native_from_sentinel(self) -> None:
+        payload = [capability.to_dict() for capability in discover_capabilities()]
+        names = {item["name"] for item in payload}
+        # The misleading unconditional `command.exit_code.native` is gone; the
+        # capability now states the mechanism per backend.
+        self.assertNotIn("command.exit_code.native", names)
+        exit_code = next(item for item in payload if item["name"] == "command.exit_code")
+        self.assertTrue(exit_code["available"])
+        details = exit_code["details"]
+        # cmd/bash scrape the exit status from a stdout sentinel; only hosted
+        # PowerShell reads it natively in-process.
+        self.assertEqual(details["cmd"], "sentinel_parsed")
+        self.assertEqual(details["bash"], "sentinel_parsed")
+        self.assertEqual(details["hosted_powershell"], "native")
+
 
 if __name__ == "__main__":
     unittest.main()