Consolidate domain exceptions into app.exceptions

Move all shared domain exception classes to backend/app/exceptions.py and update services/routers to import the canonical exceptions. Update docs to reflect the shared exceptions source.

backend/app/services/action_config_service.py

@@ -7,7 +7,6 @@ for fail2ban action configurations.
 from __future__ import annotations
 
 import asyncio
-from app.utils.async_utils import run_blocking
 import configparser
 import contextlib
 import io
@@ -18,7 +17,15 @@ from pathlib import Path
 
 import structlog
 
-from app.exceptions import ConfigWriteError, JailNotFoundInConfigError
+from app.exceptions import (
+    ActionAlreadyExistsError,
+    ActionNameError,
+    ActionNotFoundError,
+    ActionReadonlyError,
+    ConfigWriteError,
+    JailNameError,
+    JailNotFoundInConfigError,
+)
 from app.helpers.config_file_helpers import (
     _get_active_jail_names,
     _parse_jails_sync,
@@ -33,59 +40,10 @@ from app.models.config import (
     AssignActionRequest,
 )
 from app.utils import conffile_parser
+from app.utils.async_utils import run_blocking
 
 log: structlog.stdlib.BoundLogger = structlog.get_logger()
 
-# ---------------------------------------------------------------------------
-# Custom exceptions
-# ---------------------------------------------------------------------------
-
-
-class ActionNotFoundError(Exception):
-    """Raised when the requested action name is not found in ``action.d/``."""
-
-    def __init__(self, name: str) -> None:
-        """Initialise with the action name that was not found.
-
-        Args:
-            name: The action name that could not be located.
-        """
-        self.name: str = name
-        super().__init__(f"Action not found: {name!r}")
-
-
-class ActionAlreadyExistsError(Exception):
-    """Raised when trying to create an action whose ``.conf`` or ``.local`` already exists."""
-
-    def __init__(self, name: str) -> None:
-        """Initialise with the action name that already exists.
-
-        Args:
-            name: The action name that already exists.
-        """
-        self.name: str = name
-        super().__init__(f"Action already exists: {name!r}")
-
-
-class ActionReadonlyError(Exception):
-    """Raised when trying to delete a shipped ``.conf`` action with no ``.local`` override."""
-
-    def __init__(self, name: str) -> None:
-        """Initialise with the action name that cannot be deleted.
-
-        Args:
-            name: The action name that is read-only (shipped ``.conf`` only).
-        """
-        self.name: str = name
-        super().__init__(
-            f"Action {name!r} is a shipped default (.conf only); only user-created .local files can be deleted."
-        )
-
-
-class ActionNameError(Exception):
-    """Raised when an action name contains invalid characters."""
-
-
 # ---------------------------------------------------------------------------
 # Constants
 # ---------------------------------------------------------------------------
@@ -108,15 +66,6 @@ _TRUE_VALUES: frozenset[str] = frozenset({"true", "yes", "1"})
 _FALSE_VALUES: frozenset[str] = frozenset({"false", "no", "0"})
 
 
-# ---------------------------------------------------------------------------
-# Helper exceptions
-# ---------------------------------------------------------------------------
-
-
-class JailNameError(Exception):
-    """Raised when a jail name contains invalid characters."""
-
-
 # ---------------------------------------------------------------------------
 # Internal helpers
 # ---------------------------------------------------------------------------
@@ -601,7 +550,6 @@ async def list_actions(
         ``used_by_jails`` lists.
     """
     action_d = Path(config_dir) / "action.d"
-    loop = asyncio.get_event_loop()
 
     raw_actions: list[tuple[str, str, str, bool, str]] = await run_blocking( _parse_actions_sync, action_d)
 
@@ -676,7 +624,6 @@ async def get_action(
     action_d = Path(config_dir) / "action.d"
     conf_path = action_d / f"{base_name}.conf"
     local_path = action_d / f"{base_name}.local"
-    loop = asyncio.get_event_loop()
 
     def _read() -> tuple[str, bool, str]:
         """Read action content and return (content, has_local_override, source_path)."""
@@ -787,7 +734,6 @@ async def update_action(
     content = conffile_parser.serialize_action_config(merged)
 
     action_d = Path(config_dir) / "action.d"
-    loop = asyncio.get_event_loop()
     await run_blocking( _write_action_local_sync, action_d, base_name, content)
 
     if do_reload:
@@ -840,7 +786,6 @@ async def create_action(
         if conf_path.is_file() or local_path.is_file():
             raise ActionAlreadyExistsError(req.name)
 
-    loop = asyncio.get_event_loop()
     await run_blocking( _check_not_exists)
 
     cfg = ActionConfig(
@@ -903,7 +848,6 @@ async def delete_action(
     conf_path = action_d / f"{base_name}.conf"
     local_path = action_d / f"{base_name}.local"
 
-    loop = asyncio.get_event_loop()
 
     def _delete() -> None:
         has_conf = conf_path.is_file()
@@ -957,7 +901,6 @@ async def assign_action_to_jail(
     _safe_jail_name(jail_name)
     _safe_action_name(req.action_name)
 
-    loop = asyncio.get_event_loop()
 
     all_jails, _src = await run_blocking( _parse_jails_sync, Path(config_dir))
     if jail_name not in all_jails:
@@ -1035,7 +978,6 @@ async def remove_action_from_jail(
     _safe_jail_name(jail_name)
     _safe_action_name(action_name)
 
-    loop = asyncio.get_event_loop()
 
     all_jails, _src = await run_blocking( _parse_jails_sync, Path(config_dir))
     if jail_name not in all_jails: