fix(runtime): separate CommandError from InterfacyError

interfacy/common/console.py

@@ -5,8 +5,6 @@
 
 from stdl.st import colored
 
-from interfacy.exceptions import CommandError
-
 
 def info(message: str) -> None:
     print(message, file=sys.stdout)
@@ -39,12 +37,14 @@ def log_exception(tag: str, exc: BaseException, *, full_traceback: bool) -> None
         ]
         error("\n".join(["Traceback (most recent call last):", *frames]))
 
-    message = colored(
-        str(exc) if isinstance(exc, CommandError) else type(exc).__name__, color="red"
-    )
+    message = colored(type(exc).__name__, color="red")
     error(message)
 
 
+def log_command_error(exc: BaseException) -> None:
+    error(colored(str(exc), color="red"))
+
+
 def log_interrupt(*, silent: bool) -> None:
     if silent:
         return
@@ -57,6 +57,7 @@ def log_interrupt(*, silent: bool) -> None:
     "error",
     "info",
     "log",
+    "log_command_error",
     "log_error",
     "log_exception",
     "log_interrupt",

interfacy/exceptions.py

@@ -35,8 +35,12 @@ class InterfacyError(Exception):
     """Base exception for Interfacy errors."""
 
 
-class CommandError(InterfacyError):
-    """A command failure whose message is safe to display verbatim to the user."""
+class CommandError(Exception):
+    """Raise from a command for a failure whose message is written for the user.
+
+    ``run()`` prints the message, without chained causes, and exits with
+    ``ExitCode.COMMAND_FAILED``. Other command exceptions print only their type.
+    """
 
 
 class InterfacyExit(BaseException):

interfacy/runtime/invocation.py

@@ -7,7 +7,7 @@
 from inspect import isawaitable
 from typing import Any, NoReturn
 
-from interfacy.common.console import error
+from interfacy.common.console import error, log_command_error
 from interfacy.common.resources import ResourceStack
 from interfacy.declarations.executable_flags import ExecutableAction
 from interfacy.exceptions import (
@@ -77,8 +77,6 @@ def __init__(self, code: int, error: Exception) -> None:
 
 
 def _execution_error_code(error: Exception) -> ExitCode:
-    if isinstance(error, CommandError):
-        return ExitCode.COMMAND_FAILED
     if isinstance(error, PipeInputError):
         return ExitCode.USAGE
     if isinstance(error, _CONFIGURATION_ERRORS):
@@ -148,6 +146,8 @@ def run(self, parse: ParseStep, execute: ExecuteStep) -> NoReturn:
                     exit_code = rendering_error.code
                 else:
                     error(rendered.rstrip())
+            elif isinstance(failure, CommandError):
+                log_command_error(failure)
             else:
                 self._policy.log_exception(failure)
         else:

tests/unit/runtime/test_invocation.py

@@ -131,7 +131,9 @@ def command() -> None:
     )
     assert "private note" not in captured.err
     assert "private cause" not in captured.err
-    assert ("Traceback" in captured.err) == full_traceback
+    assert ("Traceback" in captured.err) == (
+        full_traceback and not issubclass(failure_type, CommandError)
+    )
 
 
 @pytest.mark.parametrize("mode", ["sync", "async"])