refactor(filesystem): split into 5 atomic free-function ops + use cases

Replaces the monolithic FileManager class + scattered helpers in
alfred/infrastructure/filesystem with five free functions, each
single-responsibility and pathlib-native:

  list_dir / create_dir / link_file / move_file / move_dir

The infra layer now raises typed exceptions (FilesystemError base
+ SourceNotFound / DestinationExists / NotADirectory / NotAFile /
PermissionDenied / CrossDevice / FilesystemOSError) instead of
returning {status: ok|error} dicts. No more get_memory() reads
from infra.

Application layer mirrors the same split: five free use cases
(<op>_use_case) wrap each infra op, guard inputs against escaping
the new DirectoryRoots VO (downloads / torrents / movies /
tv_shows), catch infra exceptions, and return frozen DTOs. Roots
are injected — no global state.

Legacy files kept on disk with _OLD suffix for reference during
the follow-up rewiring (FileManager, MediaOrganizer,
create_folder/move helpers; CreateSeedLinks/ListFolder/MoveMedia/
ManageSubtitles use cases, resolve_destination). They are no
longer exported from __init__, which intentionally breaks current
agent tool wrappers and downstream tests — re-wiring is the next
chunk of work on the unfuck branch.

CHANGELOG.md

@@ -15,6 +15,38 @@ callers).
 
 ## [Unreleased]
 
+### Changed
+
+- **`filesystem` infra + application rewritten as 5 atomic free
+  functions.** On branch `unfuck`. Replaces the monolithic
+  `FileManager` class + scattered helpers with five small, pure ops in
+  `alfred/infrastructure/filesystem/`: `list_dir`, `create_dir`,
+  `link_file`, `move_file`, `move_dir`. Each takes `pathlib.Path`
+  arguments and raises typed exceptions from a dedicated hierarchy
+  (`FilesystemError` → `SourceNotFound` / `DestinationExists` /
+  `NotADirectory` / `NotAFile` / `PermissionDenied` / `CrossDevice` /
+  `FilesystemOSError`) — no more `{"status": "ok" | "error"}` dicts at
+  the infra boundary, no more `get_memory()` reads.
+- **`filesystem` application: 5 use cases as free functions.** A
+  matching `<op>_use_case(path, …, roots: DirectoryRoots)` wraps each
+  infra op, guards inputs against escaping a new `DirectoryRoots` VO
+  (downloads / torrents / movies / tv_shows), catches infra exceptions,
+  and returns a frozen `<Op>Response` DTO. Roots are now injected, not
+  pulled from the global memory singleton.
+
+### Removed
+
+- `FileManager` / `MediaOrganizer` / `create_folder` / `move` from the
+  public API of `alfred.infrastructure.filesystem`. Their files remain
+  on disk renamed with an `_OLD` suffix (e.g. `file_manager_OLD.py`) so
+  the migration can finish on a follow-up commit without losing
+  reference material. They are no longer re-exported from `__init__`.
+- `CreateSeedLinksUseCase` / `ListFolderUseCase` / `MoveMediaUseCase` /
+  `ManageSubtitlesUseCase` / `resolve_destination` from the public API
+  of `alfred.application.filesystem`. Same `_OLD` rename treatment.
+  This intentionally breaks current tool wrappers and tests downstream
+  — re-wiring is the next chunk of work on this branch.
+
 ### Added
 
 - **`.alfred` v2 — Phase 4: v2-shaped `rescan_show` + new

alfred/application/filesystem/__init__.py

@@ -1,43 +1,42 @@
-"""Filesystem use cases."""
+"""Filesystem application layer — 5 atomic use cases as free functions.
 
-from .create_seed_links import CreateSeedLinksUseCase
+Each use case:
+- accepts :class:`pathlib.Path` inputs plus a :class:`DirectoryRoots` VO,
+- guards inputs against escaping configured roots,
+- calls the matching infra op,
+- catches :class:`~alfred.infrastructure.filesystem.FilesystemError` and
+  returns a frozen DTO with a normalized error code.
+
+No global state, no ``get_memory()``. Roots are injected.
+"""
+
+from .create_dir import create_dir_use_case
+from .directory_roots import DirectoryRoots
 from .dto import (
-    CreateSeedLinksResponse,
-    ListFolderResponse,
-    ManageSubtitlesResponse,
-    MoveMediaResponse,
-    PlacedSubtitle,
- )
-from .list_folder import ListFolderUseCase
-from .manage_subtitles import ManageSubtitlesUseCase
-from .move_media import MoveMediaUseCase
-from .resolve_destination import (
-    ResolvedEpisodeDestination,
-    ResolvedMovieDestination,
-    ResolvedSeasonDestination,
-    ResolvedSeriesDestination,
-    resolve_episode_destination,
-    resolve_movie_destination,
-    resolve_season_destination,
-    resolve_series_destination,
+    CreateDirResponse,
+    LinkFileResponse,
+    ListDirResponse,
+    MoveDirResponse,
+    MoveFileResponse,
 )
+from .link_file import link_file_use_case
+from .list_dir import list_dir_use_case
+from .move_dir import move_dir_use_case
+from .move_file import move_file_use_case
 
 __all__ = [
-    "ListFolderUseCase",
-    "CreateSeedLinksUseCase",
-    "MoveMediaUseCase",
-    "ManageSubtitlesUseCase",
-    "ResolvedSeasonDestination",
-    "ResolvedEpisodeDestination",
-    "ResolvedMovieDestination",
-    "ResolvedSeriesDestination",
-    "resolve_season_destination",
-    "resolve_episode_destination",
-    "resolve_movie_destination",
-    "resolve_series_destination",
-    "ListFolderResponse",
-    "CreateSeedLinksResponse",
-    "MoveMediaResponse",
-    "ManageSubtitlesResponse",
-    "PlacedSubtitle",
+    # use cases
+    "list_dir_use_case",
+    "create_dir_use_case",
+    "link_file_use_case",
+    "move_file_use_case",
+    "move_dir_use_case",
+    # VO
+    "DirectoryRoots",
+    # DTOs
+    "ListDirResponse",
+    "CreateDirResponse",
+    "LinkFileResponse",
+    "MoveFileResponse",
+    "MoveDirResponse",
 ]

alfred/application/filesystem/_errors.py

@@ -0,0 +1,41 @@
+"""Internal helpers: mapping infra exceptions → error codes.
+
+Kept private (``_errors``) — only the 5 use cases in this package use
+it. Centralizes the exception → code translation so every use case
+returns consistent error payloads.
+"""
+
+from __future__ import annotations
+
+from alfred.infrastructure.filesystem import (
+    CrossDevice,
+    DestinationExists,
+    FilesystemError,
+    FilesystemOSError,
+    NotADirectory,
+    NotAFile,
+    PermissionDenied,
+    SourceNotFound,
+)
+
+# Application-layer error codes (guard violations, not infra).
+PATH_NOT_ALLOWED = "path_not_allowed"
+
+
+def code_for(exc: FilesystemError) -> str:
+    """Return the snake-case error code for an infra exception."""
+    if isinstance(exc, SourceNotFound):
+        return "source_not_found"
+    if isinstance(exc, DestinationExists):
+        return "destination_exists"
+    if isinstance(exc, NotADirectory):
+        return "not_a_directory"
+    if isinstance(exc, NotAFile):
+        return "not_a_file"
+    if isinstance(exc, PermissionDenied):
+        return "permission_denied"
+    if isinstance(exc, CrossDevice):
+        return "cross_device"
+    if isinstance(exc, FilesystemOSError):
+        return "filesystem_os_error"
+    return "filesystem_error"

alfred/application/filesystem/create_dir.py

@@ -0,0 +1,33 @@
+"""create_dir use case — create a directory under one of the configured roots."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from alfred.infrastructure.filesystem import FilesystemError, create_dir
+
+from ._errors import PATH_NOT_ALLOWED, code_for
+from .directory_roots import DirectoryRoots
+from .dto import CreateDirResponse
+
+
+def create_dir_use_case(path: Path, roots: DirectoryRoots) -> CreateDirResponse:
+    """Create directory ``path`` (and any missing parents) provided it
+    lives under one of the configured roots.
+
+    Idempotent on the infra side: re-running on an existing directory
+    returns ``status="ok"``.
+    """
+    if not roots.contains(path):
+        return CreateDirResponse(
+            status="error",
+            error=PATH_NOT_ALLOWED,
+            message=f"Path is outside configured roots: {path}",
+        )
+
+    try:
+        create_dir(path)
+    except FilesystemError as e:
+        return CreateDirResponse(status="error", error=code_for(e), message=str(e))
+
+    return CreateDirResponse(status="ok", path=path)

alfred/application/filesystem/directory_roots.py

@@ -0,0 +1,56 @@
+"""DirectoryRoots — VO carrying the configured filesystem roots.
+
+Replaces the ad-hoc ``get_memory().ltm.workspace.<x>`` lookups that were
+sprinkled across the filesystem use cases. By making roots an explicit
+input, use cases become pure (no global state read) and easy to test.
+
+The roots are read once at the tool wrapper boundary (where the agent
+config lives) and threaded through the use cases.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from pathlib import Path
+
+
+@dataclass(frozen=True)
+class DirectoryRoots:
+    """Configured roots of Alfred's filesystem.
+
+    All paths must be absolute and existing directories — validation is
+    expected at the boundary that builds this VO.
+
+    Attributes:
+        downloads: where qBittorrent drops finished torrents.
+        torrents: where seeding hard-links live (mirrors downloads/).
+        movies: library root for movies.
+        tv_shows: library root for TV shows.
+    """
+
+    downloads: Path
+    torrents: Path
+    movies: Path
+    tv_shows: Path
+
+    def all(self) -> tuple[Path, ...]:
+        """Return every configured root, in declaration order."""
+        return (self.downloads, self.torrents, self.movies, self.tv_shows)
+
+    def contains(self, path: Path) -> bool:
+        """Return True if ``path`` is inside one of the configured roots.
+
+        Uses ``Path.resolve()`` to handle symlinks and ``..`` segments,
+        then ``relative_to`` for an exact within-root check.
+        """
+        try:
+            resolved = path.resolve()
+        except OSError:
+            return False
+        for root in self.all():
+            try:
+                resolved.relative_to(root.resolve())
+                return True
+            except (ValueError, OSError):
+                continue
+        return False

alfred/application/filesystem/dto.py

@@ -1,19 +1,28 @@
-"""Filesystem application DTOs."""
+"""DTOs for the 5 atomic filesystem use cases.
+
+Each use case returns a small frozen dataclass tagged with a ``status``
+field. On error, ``error`` (machine-readable code) and ``message``
+(human-readable) are populated; on success, the relevant payload
+fields are.
+
+Error codes mirror the infrastructure exception types (lowercased,
+snake-cased) — e.g. ``SourceNotFound`` → ``"source_not_found"`` — plus
+the application-layer ``"path_not_allowed"`` for guard violations.
+"""
 
 from __future__ import annotations
 
-from dataclasses import dataclass
+from dataclasses import dataclass, field
+from pathlib import Path
 
 
-@dataclass
-class CopyMediaResponse:
-    """Response from copying a media file."""
+@dataclass(frozen=True)
+class ListDirResponse:
+    """Response from ``list_dir_use_case``."""
 
-    status: str
-    source: str | None = None
-    destination: str | None = None
-    filename: str | None = None
-    size: int | None = None
+    status: str  # "ok" | "error"
+    path: Path | None = None
+    entries: tuple[Path, ...] = ()
     error: str | None = None
     message: str | None = None
 
@@ -22,22 +31,33 @@ class CopyMediaResponse:
             return {"status": self.status, "error": self.error, "message": self.message}
         return {
             "status": self.status,
-            "source": self.source,
-            "destination": self.destination,
-            "filename": self.filename,
-            "size": self.size,
+            "path": str(self.path) if self.path else None,
+            "entries": [str(p) for p in self.entries],
         }
 
 
-@dataclass
-class MoveMediaResponse:
-    """Response from moving a media file."""
+@dataclass(frozen=True)
+class CreateDirResponse:
+    """Response from ``create_dir_use_case``."""
 
     status: str
-    source: str | None = None
-    destination: str | None = None
-    filename: str | None = None
-    size: int | None = None
+    path: Path | None = None
+    error: str | None = None
+    message: str | None = None
+
+    def to_dict(self) -> dict:
+        if self.error:
+            return {"status": self.status, "error": self.error, "message": self.message}
+        return {"status": self.status, "path": str(self.path) if self.path else None}
+
+
+@dataclass(frozen=True)
+class LinkFileResponse:
+    """Response from ``link_file_use_case``."""
+
+    status: str
+    source: Path | None = None
+    destination: Path | None = None
     error: str | None = None
     message: str | None = None
 
@@ -46,100 +66,18 @@ class MoveMediaResponse:
             return {"status": self.status, "error": self.error, "message": self.message}
         return {
             "status": self.status,
-            "source": self.source,
-            "destination": self.destination,
-            "filename": self.filename,
-            "size": self.size,
+            "source": str(self.source) if self.source else None,
+            "destination": str(self.destination) if self.destination else None,
         }
 
 
-
-@dataclass
-class PlacedSubtitle:
-    """One subtitle file successfully placed."""
-
-    source: str
-    destination: str
-    filename: str
-
-    def to_dict(self) -> dict:
-        return {
-            "source": self.source,
-            "destination": self.destination,
-            "filename": self.filename,
-        }
-
-
-@dataclass
-class UnresolvedTrack:
-    """A subtitle track that needs agent clarification before placement."""
-
-    raw_tokens: list[str]
-    file_path: str | None = None
-    file_size_kb: float | None = None
-    reason: str = ""  # "unknown_language" | "low_confidence"
-
-    def to_dict(self) -> dict:
-        return {
-            "raw_tokens": self.raw_tokens,
-            "file_path": self.file_path,
-            "file_size_kb": self.file_size_kb,
-            "reason": self.reason,
-        }
-
-
-@dataclass
-class AvailableSubtitle:
-    """One subtitle track available on an embedded media item."""
-
-    language: str  # ISO 639-2 code
-    subtitle_type: str  # "standard" | "sdh" | "forced" | "unknown"
-
-    def to_dict(self) -> dict:
-        return {"language": self.language, "type": self.subtitle_type}
-
-
-@dataclass
-class ManageSubtitlesResponse:
-    """Response from the manage_subtitles use case."""
-
-    status: str  # "ok" | "needs_clarification" | "error"
-    video_path: str | None = None
-    placed: list[PlacedSubtitle] | None = None
-    skipped_count: int = 0
-    unresolved: list[UnresolvedTrack] | None = None
-    available: list[AvailableSubtitle] | None = None  # embedded tracks summary
-    error: str | None = None
-    message: str | None = None
-
-    def to_dict(self) -> dict:
-        if self.error:
-            return {"status": self.status, "error": self.error, "message": self.message}
-        result = {
-            "status": self.status,
-            "video_path": self.video_path,
-            "placed": [p.to_dict() for p in (self.placed or [])],
-            "placed_count": len(self.placed or []),
-            "skipped_count": self.skipped_count,
-        }
-        if self.unresolved:
-            result["unresolved"] = [u.to_dict() for u in self.unresolved]
-            result["unresolved_count"] = len(self.unresolved)
-        if self.available:
-            result["available"] = [a.to_dict() for a in self.available]
-        return result
-
-
-@dataclass
-class CreateSeedLinksResponse:
-    """Response from creating seed links for a torrent."""
+@dataclass(frozen=True)
+class MoveFileResponse:
+    """Response from ``move_file_use_case``."""
 
     status: str
-    torrent_subfolder: str | None = None
-    linked_file: str | None = None
-    copied_files: list[str] | None = None
-    copied_count: int = 0
-    skipped: list[str] | None = None
+    source: Path | None = None
+    destination: Path | None = None
     error: str | None = None
     message: str | None = None
 
@@ -148,41 +86,26 @@ class CreateSeedLinksResponse:
             return {"status": self.status, "error": self.error, "message": self.message}
         return {
             "status": self.status,
-            "torrent_subfolder": self.torrent_subfolder,
-            "linked_file": self.linked_file,
-            "copied_files": self.copied_files or [],
-            "copied_count": self.copied_count,
-            "skipped": self.skipped or [],
+            "source": str(self.source) if self.source else None,
+            "destination": str(self.destination) if self.destination else None,
         }
 
 
-@dataclass
-class ListFolderResponse:
-    """Response from listing a folder."""
+@dataclass(frozen=True)
+class MoveDirResponse:
+    """Response from ``move_dir_use_case``."""
 
     status: str
-    folder_type: str | None = None # SHOULD BE A PROPERTY
-    path: str | None = None # NOT NONE - Should be path
-    entries: list[str] | None = None # NOT NONE - Empty list of path
-    count: int | None = None # USELESS
+    source: Path | None = None
+    destination: Path | None = None
     error: str | None = None
     message: str | None = None
 
-    def to_dict(self):
-        """Convert to dict for agent compatibility."""
-        result = {"status": self.status}
-
+    def to_dict(self) -> dict:
         if self.error:
-            result["error"] = self.error
-            result["message"] = self.message
-        else:
-            if self.folder_type:
-                result["folder_type"] = self.folder_type
-            if self.path:
-                result["path"] = self.path
-            if self.entries is not None:
-                result["entries"] = self.entries
-            if self.count is not None:
-                result["count"] = self.count
-
-        return result
+            return {"status": self.status, "error": self.error, "message": self.message}
+        return {
+            "status": self.status,
+            "source": str(self.source) if self.source else None,
+            "destination": str(self.destination) if self.destination else None,
+        }

alfred/application/filesystem/dto_OLD.py

@@ -0,0 +1,188 @@
+"""Filesystem application DTOs."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass
+class CopyMediaResponse:
+    """Response from copying a media file."""
+
+    status: str
+    source: str | None = None
+    destination: str | None = None
+    filename: str | None = None
+    size: int | None = None
+    error: str | None = None
+    message: str | None = None
+
+    def to_dict(self) -> dict:
+        if self.error:
+            return {"status": self.status, "error": self.error, "message": self.message}
+        return {
+            "status": self.status,
+            "source": self.source,
+            "destination": self.destination,
+            "filename": self.filename,
+            "size": self.size,
+        }
+
+
+@dataclass
+class MoveMediaResponse:
+    """Response from moving a media file."""
+
+    status: str
+    source: str | None = None
+    destination: str | None = None
+    filename: str | None = None
+    size: int | None = None
+    error: str | None = None
+    message: str | None = None
+
+    def to_dict(self) -> dict:
+        if self.error:
+            return {"status": self.status, "error": self.error, "message": self.message}
+        return {
+            "status": self.status,
+            "source": self.source,
+            "destination": self.destination,
+            "filename": self.filename,
+            "size": self.size,
+        }
+
+
+
+@dataclass
+class PlacedSubtitle:
+    """One subtitle file successfully placed."""
+
+    source: str
+    destination: str
+    filename: str
+
+    def to_dict(self) -> dict:
+        return {
+            "source": self.source,
+            "destination": self.destination,
+            "filename": self.filename,
+        }
+
+
+@dataclass
+class UnresolvedTrack:
+    """A subtitle track that needs agent clarification before placement."""
+
+    raw_tokens: list[str]
+    file_path: str | None = None
+    file_size_kb: float | None = None
+    reason: str = ""  # "unknown_language" | "low_confidence"
+
+    def to_dict(self) -> dict:
+        return {
+            "raw_tokens": self.raw_tokens,
+            "file_path": self.file_path,
+            "file_size_kb": self.file_size_kb,
+            "reason": self.reason,
+        }
+
+
+@dataclass
+class AvailableSubtitle:
+    """One subtitle track available on an embedded media item."""
+
+    language: str  # ISO 639-2 code
+    subtitle_type: str  # "standard" | "sdh" | "forced" | "unknown"
+
+    def to_dict(self) -> dict:
+        return {"language": self.language, "type": self.subtitle_type}
+
+
+@dataclass
+class ManageSubtitlesResponse:
+    """Response from the manage_subtitles use case."""
+
+    status: str  # "ok" | "needs_clarification" | "error"
+    video_path: str | None = None
+    placed: list[PlacedSubtitle] | None = None
+    skipped_count: int = 0
+    unresolved: list[UnresolvedTrack] | None = None
+    available: list[AvailableSubtitle] | None = None  # embedded tracks summary
+    error: str | None = None
+    message: str | None = None
+
+    def to_dict(self) -> dict:
+        if self.error:
+            return {"status": self.status, "error": self.error, "message": self.message}
+        result = {
+            "status": self.status,
+            "video_path": self.video_path,
+            "placed": [p.to_dict() for p in (self.placed or [])],
+            "placed_count": len(self.placed or []),
+            "skipped_count": self.skipped_count,
+        }
+        if self.unresolved:
+            result["unresolved"] = [u.to_dict() for u in self.unresolved]
+            result["unresolved_count"] = len(self.unresolved)
+        if self.available:
+            result["available"] = [a.to_dict() for a in self.available]
+        return result
+
+
+@dataclass
+class CreateSeedLinksResponse:
+    """Response from creating seed links for a torrent."""
+
+    status: str
+    torrent_subfolder: str | None = None
+    linked_file: str | None = None
+    copied_files: list[str] | None = None
+    copied_count: int = 0
+    skipped: list[str] | None = None
+    error: str | None = None
+    message: str | None = None
+
+    def to_dict(self) -> dict:
+        if self.error:
+            return {"status": self.status, "error": self.error, "message": self.message}
+        return {
+            "status": self.status,
+            "torrent_subfolder": self.torrent_subfolder,
+            "linked_file": self.linked_file,
+            "copied_files": self.copied_files or [],
+            "copied_count": self.copied_count,
+            "skipped": self.skipped or [],
+        }
+
+
+@dataclass
+class ListFolderResponse:
+    """Response from listing a folder."""
+
+    status: str
+    folder_type: str | None = None # SHOULD BE A PROPERTY
+    path: str | None = None # NOT NONE - Should be path
+    entries: list[str] | None = None # NOT NONE - Empty list of path
+    count: int | None = None # USELESS
+    error: str | None = None
+    message: str | None = None
+
+    def to_dict(self):
+        """Convert to dict for agent compatibility."""
+        result = {"status": self.status}
+
+        if self.error:
+            result["error"] = self.error
+            result["message"] = self.message
+        else:
+            if self.folder_type:
+                result["folder_type"] = self.folder_type
+            if self.path:
+                result["path"] = self.path
+            if self.entries is not None:
+                result["entries"] = self.entries
+            if self.count is not None:
+                result["count"] = self.count
+
+        return result

alfred/application/filesystem/link_file.py

@@ -0,0 +1,40 @@
+"""link_file use case — hard-link a file from one root to another."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from alfred.infrastructure.filesystem import FilesystemError, link_file
+
+from ._errors import PATH_NOT_ALLOWED, code_for
+from .directory_roots import DirectoryRoots
+from .dto import LinkFileResponse
+
+
+def link_file_use_case(
+    src: Path, dst: Path, roots: DirectoryRoots
+) -> LinkFileResponse:
+    """Hard-link ``src`` to ``dst``. Both must be under configured roots.
+
+    The destination parent must already exist — the caller is expected
+    to have created it via ``create_dir_use_case`` if needed.
+    """
+    if not roots.contains(src):
+        return LinkFileResponse(
+            status="error",
+            error=PATH_NOT_ALLOWED,
+            message=f"Source is outside configured roots: {src}",
+        )
+    if not roots.contains(dst):
+        return LinkFileResponse(
+            status="error",
+            error=PATH_NOT_ALLOWED,
+            message=f"Destination is outside configured roots: {dst}",
+        )
+
+    try:
+        link_file(src, dst)
+    except FilesystemError as e:
+        return LinkFileResponse(status="error", error=code_for(e), message=str(e))
+
+    return LinkFileResponse(status="ok", source=src, destination=dst)

alfred/application/filesystem/list_dir.py

@@ -0,0 +1,34 @@
+"""list_dir use case — list a directory after guarding it within roots."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from alfred.infrastructure.filesystem import FilesystemError, list_dir
+
+from ._errors import PATH_NOT_ALLOWED, code_for
+from .directory_roots import DirectoryRoots
+from .dto import ListDirResponse
+
+
+def list_dir_use_case(path: Path, roots: DirectoryRoots) -> ListDirResponse:
+    """List the immediate children of ``path`` if it lives under one of
+    the configured roots.
+
+    Returns a :class:`ListDirResponse`. On guard failure, status is
+    ``"error"`` with ``error="path_not_allowed"``. On infra failure,
+    status is ``"error"`` with a code mapped from the raised exception.
+    """
+    if not roots.contains(path):
+        return ListDirResponse(
+            status="error",
+            error=PATH_NOT_ALLOWED,
+            message=f"Path is outside configured roots: {path}",
+        )
+
+    try:
+        entries = list_dir(path)
+    except FilesystemError as e:
+        return ListDirResponse(status="error", error=code_for(e), message=str(e))
+
+    return ListDirResponse(status="ok", path=path, entries=tuple(entries))

alfred/application/filesystem/move_dir.py

@@ -0,0 +1,36 @@
+"""move_dir use case — move a directory tree between configured roots."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from alfred.infrastructure.filesystem import FilesystemError, move_dir
+
+from ._errors import PATH_NOT_ALLOWED, code_for
+from .directory_roots import DirectoryRoots
+from .dto import MoveDirResponse
+
+
+def move_dir_use_case(
+    src: Path, dst: Path, roots: DirectoryRoots
+) -> MoveDirResponse:
+    """Move directory ``src`` to ``dst``. Both must be under configured roots."""
+    if not roots.contains(src):
+        return MoveDirResponse(
+            status="error",
+            error=PATH_NOT_ALLOWED,
+            message=f"Source is outside configured roots: {src}",
+        )
+    if not roots.contains(dst):
+        return MoveDirResponse(
+            status="error",
+            error=PATH_NOT_ALLOWED,
+            message=f"Destination is outside configured roots: {dst}",
+        )
+
+    try:
+        move_dir(src, dst)
+    except FilesystemError as e:
+        return MoveDirResponse(status="error", error=code_for(e), message=str(e))
+
+    return MoveDirResponse(status="ok", source=src, destination=dst)

alfred/application/filesystem/move_file.py

@@ -0,0 +1,36 @@
+"""move_file use case — move a file between configured roots."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from alfred.infrastructure.filesystem import FilesystemError, move_file
+
+from ._errors import PATH_NOT_ALLOWED, code_for
+from .directory_roots import DirectoryRoots
+from .dto import MoveFileResponse
+
+
+def move_file_use_case(
+    src: Path, dst: Path, roots: DirectoryRoots
+) -> MoveFileResponse:
+    """Move file ``src`` to ``dst``. Both must be under configured roots."""
+    if not roots.contains(src):
+        return MoveFileResponse(
+            status="error",
+            error=PATH_NOT_ALLOWED,
+            message=f"Source is outside configured roots: {src}",
+        )
+    if not roots.contains(dst):
+        return MoveFileResponse(
+            status="error",
+            error=PATH_NOT_ALLOWED,
+            message=f"Destination is outside configured roots: {dst}",
+        )
+
+    try:
+        move_file(src, dst)
+    except FilesystemError as e:
+        return MoveFileResponse(status="error", error=code_for(e), message=str(e))
+
+    return MoveFileResponse(status="ok", source=src, destination=dst)

alfred/infrastructure/filesystem/__init__.py

@@ -1,15 +1,44 @@
-"""Filesystem operations."""
+"""Filesystem infrastructure — 5 atomic ops as free functions.
 
-from .exceptions import FilesystemError, PathTraversalError
-from .file_manager import FileManager
-from .filesystem_operations import create_folder, move
-from .organizer import MediaOrganizer
+All ops use :class:`pathlib.Path` and raise typed exceptions from
+:mod:`.exceptions` on failure. They do **not** return status dicts and
+do **not** read application state (no ``get_memory()``).
+
+The application layer (``alfred.application.filesystem``) is responsible
+for guarding paths against escaping configured roots and for wrapping
+exceptions into DTOs.
+"""
+
+from .create_dir import create_dir
+from .exceptions import (
+    CrossDevice,
+    DestinationExists,
+    FilesystemError,
+    FilesystemOSError,
+    NotADirectory,
+    NotAFile,
+    PermissionDenied,
+    SourceNotFound,
+)
+from .link_file import link_file
+from .list_dir import list_dir
+from .move_dir import move_dir
+from .move_file import move_file
 
 __all__ = [
-    "FileManager",
-    "MediaOrganizer",
+    # ops
+    "list_dir",
+    "create_dir",
+    "link_file",
+    "move_file",
+    "move_dir",
+    # exceptions
     "FilesystemError",
-    "PathTraversalError",
-    "create_folder",
-    "move",
+    "SourceNotFound",
+    "DestinationExists",
+    "NotADirectory",
+    "NotAFile",
+    "PermissionDenied",
+    "CrossDevice",
+    "FilesystemOSError",
 ]

alfred/infrastructure/filesystem/create_dir.py

@@ -0,0 +1,33 @@
+"""create_dir — create a directory (and missing parents)."""
+
+from __future__ import annotations
+
+import errno
+from pathlib import Path
+
+from .exceptions import FilesystemOSError, NotADirectory, PermissionDenied
+
+
+def create_dir(path: Path) -> None:
+    """Create ``path`` and any missing parents.
+
+    Idempotent: if ``path`` already exists **and is a directory**, this
+    is a no-op. If it exists but is not a directory, raises
+    :class:`NotADirectory`.
+
+    Raises:
+        NotADirectory: ``path`` exists but is not a directory.
+        PermissionDenied: parent is not writable.
+        FilesystemOSError: any other ``OSError`` from ``mkdir``.
+    """
+    if path.exists() and not path.is_dir():
+        raise NotADirectory(path)
+
+    try:
+        path.mkdir(parents=True, exist_ok=True)
+    except PermissionError as e:
+        raise PermissionDenied(path, action="create_dir") from e
+    except OSError as e:
+        if e.errno == errno.EACCES:
+            raise PermissionDenied(path, action="create_dir") from e
+        raise FilesystemOSError("create_dir", path, e) from e

alfred/infrastructure/filesystem/exceptions.py

@@ -1,25 +1,92 @@
-"""Filesystem exceptions."""
+"""Filesystem infrastructure exceptions.
+
+Convention: the 5 atomic ops (``list_dir``, ``create_dir``, ``link_file``,
+``move_file``, ``move_dir``) raise typed exceptions on failure rather
+than returning ``T | None`` or status dicts. The application layer
+catches these and wraps them into DTOs.
+
+Hierarchy:
+
+    FilesystemError
+        SourceNotFound
+        DestinationExists
+        NotADirectory
+        NotAFile
+        PermissionDenied
+        CrossDevice
+        FilesystemOSError      # catch-all for unexpected OSError
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
 
 
 class FilesystemError(Exception):
-    """Base exception for filesystem operations."""
-
-    pass
+    """Base exception for all filesystem infrastructure failures."""
 
 
-class PathTraversalError(FilesystemError):
-    """Raised when path traversal attack is detected."""
+class SourceNotFound(FilesystemError):
+    """The source path does not exist."""
 
-    pass
+    def __init__(self, path: Path):
+        super().__init__(f"Source does not exist: {path}")
+        self.path = path
 
 
-class FileNotFoundError(FilesystemError):
-    """Raised when a file is not found."""
+class DestinationExists(FilesystemError):
+    """The destination already exists (refuse to overwrite)."""
 
-    pass
+    def __init__(self, path: Path):
+        super().__init__(f"Destination already exists: {path}")
+        self.path = path
 
 
-class PermissionDeniedError(FilesystemError):
-    """Raised when permission is denied."""
+class NotADirectory(FilesystemError):
+    """The path exists but is not a directory."""
 
-    pass
+    def __init__(self, path: Path):
+        super().__init__(f"Not a directory: {path}")
+        self.path = path
+
+
+class NotAFile(FilesystemError):
+    """The path exists but is not a regular file."""
+
+    def __init__(self, path: Path):
+        super().__init__(f"Not a file: {path}")
+        self.path = path
+
+
+class PermissionDenied(FilesystemError):
+    """OS denied the requested operation."""
+
+    def __init__(self, path: Path, action: str):
+        super().__init__(f"Permission denied ({action}): {path}")
+        self.path = path
+        self.action = action
+
+
+class CrossDevice(FilesystemError):
+    """Source and destination live on different filesystems.
+
+    On Alfred's ZFS pool this should never happen. If it does, it is a
+    configuration bug, not something to silently fall back from.
+    """
+
+    def __init__(self, source: Path, destination: Path):
+        super().__init__(
+            f"Cross-device operation refused: {source} → {destination}"
+        )
+        self.source = source
+        self.destination = destination
+
+
+class FilesystemOSError(FilesystemError):
+    """Wraps an unexpected ``OSError`` from the underlying syscall."""
+
+    def __init__(self, action: str, path: Path, cause: OSError):
+        super().__init__(f"{action} failed for {path}: {cause}")
+        self.action = action
+        self.path = path
+        self.cause = cause

alfred/infrastructure/filesystem/link_file.py

@@ -0,0 +1,61 @@
+"""link_file — create a hard link from ``src`` to ``dst``.
+
+Hard-link semantics: ``dst`` becomes a second name for the same inode
+as ``src``. Zero data copy, instant on any filesystem, and qBittorrent
+keeps seeding the original path unaffected since the inode is unchanged.
+
+Requires ``src`` and ``dst`` to live on the same filesystem. On Alfred's
+ZFS pool this is always the case; if not, :class:`CrossDevice` is
+raised.
+"""
+
+from __future__ import annotations
+
+import errno
+import os
+from pathlib import Path
+
+from .exceptions import (
+    CrossDevice,
+    DestinationExists,
+    FilesystemOSError,
+    NotAFile,
+    PermissionDenied,
+    SourceNotFound,
+)
+
+
+def link_file(src: Path, dst: Path) -> None:
+    """Hard-link ``src`` to ``dst``.
+
+    The destination parent directory **must already exist** — caller is
+    responsible for creating it (use ``create_dir`` first if needed).
+
+    Raises:
+        SourceNotFound: ``src`` does not exist.
+        NotAFile: ``src`` is not a regular file.
+        SourceNotFound: parent of ``dst`` does not exist.
+        DestinationExists: ``dst`` already exists.
+        CrossDevice: source and destination are on different filesystems.
+        PermissionDenied: cannot create link (permission).
+        FilesystemOSError: any other ``OSError`` from ``os.link``.
+    """
+    if not src.exists():
+        raise SourceNotFound(src)
+    if not src.is_file():
+        raise NotAFile(src)
+    if not dst.parent.exists():
+        raise SourceNotFound(dst.parent)
+    if dst.exists():
+        raise DestinationExists(dst)
+
+    try:
+        os.link(src, dst)
+    except PermissionError as e:
+        raise PermissionDenied(dst, action="link_file") from e
+    except OSError as e:
+        if e.errno == errno.EXDEV:
+            raise CrossDevice(src, dst) from e
+        if e.errno == errno.EACCES:
+            raise PermissionDenied(dst, action="link_file") from e
+        raise FilesystemOSError("link_file", dst, e) from e

alfred/infrastructure/filesystem/list_dir.py

@@ -0,0 +1,40 @@
+"""list_dir — return the immediate children of a directory."""
+
+from __future__ import annotations
+
+import errno
+from pathlib import Path
+
+from .exceptions import (
+    FilesystemOSError,
+    NotADirectory,
+    PermissionDenied,
+    SourceNotFound,
+)
+
+
+def list_dir(path: Path) -> list[Path]:
+    """Return the immediate children of ``path``, sorted by name.
+
+    Returns absolute :class:`~pathlib.Path` objects for both files and
+    directories. Does not recurse.
+
+    Raises:
+        SourceNotFound: ``path`` does not exist.
+        NotADirectory: ``path`` exists but is not a directory.
+        PermissionDenied: the directory is not readable.
+        FilesystemOSError: any other ``OSError`` from ``iterdir``.
+    """
+    if not path.exists():
+        raise SourceNotFound(path)
+    if not path.is_dir():
+        raise NotADirectory(path)
+
+    try:
+        return sorted(path.iterdir())
+    except PermissionError as e:
+        raise PermissionDenied(path, action="list_dir") from e
+    except OSError as e:
+        if e.errno == errno.EACCES:
+            raise PermissionDenied(path, action="list_dir") from e
+        raise FilesystemOSError("list_dir", path, e) from e

alfred/infrastructure/filesystem/move_dir.py

@@ -0,0 +1,52 @@
+"""move_dir — move a directory tree."""
+
+from __future__ import annotations
+
+import errno
+import os
+from pathlib import Path
+
+from .exceptions import (
+    CrossDevice,
+    DestinationExists,
+    FilesystemOSError,
+    NotADirectory,
+    PermissionDenied,
+    SourceNotFound,
+)
+
+
+def move_dir(src: Path, dst: Path) -> None:
+    """Move directory ``src`` to ``dst``.
+
+    Same-filesystem rename — instant on ZFS, even for huge trees. The
+    destination parent must already exist; ``dst`` itself must not.
+
+    Raises:
+        SourceNotFound: ``src`` does not exist.
+        NotADirectory: ``src`` is not a directory.
+        SourceNotFound: parent of ``dst`` does not exist.
+        DestinationExists: ``dst`` already exists.
+        CrossDevice: source and destination are on different filesystems.
+        PermissionDenied: cannot perform the rename (permission).
+        FilesystemOSError: any other ``OSError`` from ``os.rename``.
+    """
+    if not src.exists():
+        raise SourceNotFound(src)
+    if not src.is_dir():
+        raise NotADirectory(src)
+    if not dst.parent.exists():
+        raise SourceNotFound(dst.parent)
+    if dst.exists():
+        raise DestinationExists(dst)
+
+    try:
+        os.rename(src, dst)
+    except PermissionError as e:
+        raise PermissionDenied(dst, action="move_dir") from e
+    except OSError as e:
+        if e.errno == errno.EXDEV:
+            raise CrossDevice(src, dst) from e
+        if e.errno == errno.EACCES:
+            raise PermissionDenied(dst, action="move_dir") from e
+        raise FilesystemOSError("move_dir", dst, e) from e

alfred/infrastructure/filesystem/move_file.py

@@ -0,0 +1,52 @@
+"""move_file — move a single regular file."""
+
+from __future__ import annotations
+
+import errno
+import os
+from pathlib import Path
+
+from .exceptions import (
+    CrossDevice,
+    DestinationExists,
+    FilesystemOSError,
+    NotAFile,
+    PermissionDenied,
+    SourceNotFound,
+)
+
+
+def move_file(src: Path, dst: Path) -> None:
+    """Move ``src`` to ``dst``.
+
+    Same-filesystem rename — instant on ZFS. The destination parent
+    must already exist.
+
+    Raises:
+        SourceNotFound: ``src`` does not exist.
+        NotAFile: ``src`` is not a regular file.
+        SourceNotFound: parent of ``dst`` does not exist.
+        DestinationExists: ``dst`` already exists.
+        CrossDevice: source and destination are on different filesystems.
+        PermissionDenied: cannot perform the rename (permission).
+        FilesystemOSError: any other ``OSError`` from ``os.rename``.
+    """
+    if not src.exists():
+        raise SourceNotFound(src)
+    if not src.is_file():
+        raise NotAFile(src)
+    if not dst.parent.exists():
+        raise SourceNotFound(dst.parent)
+    if dst.exists():
+        raise DestinationExists(dst)
+
+    try:
+        os.rename(src, dst)
+    except PermissionError as e:
+        raise PermissionDenied(dst, action="move_file") from e
+    except OSError as e:
+        if e.errno == errno.EXDEV:
+            raise CrossDevice(src, dst) from e
+        if e.errno == errno.EACCES:
+            raise PermissionDenied(dst, action="move_file") from e
+        raise FilesystemOSError("move_file", dst, e) from e