feat(packs): inspect multi-book releases and file each book separately (#1270)

## Multi-book packs: inspect a release before download and file each
book separately

Closes #576

### Problem

One queued release is always treated as one book. When a torrent is
actually a whole series
(`Series/Book 1 - Title/…`, or a flat folder of `Series 1.0 - Title.m4b`
files), post-processing
walks the whole tree, flattens every file into one list and renames them
`Title - 01…10` under the
searched book's `{Author}/{Title}`. Audiobookshelf then sees a single
10-file "book" and the user
has to re-file everything by hand.

### What this does

Most releases expose their file list *before* anything is downloaded, so
the split is decided up
front and approved by the user, then the download is fire-and-forget:

1. **Inspect** – clicking a release's download button now calls `POST
/api/releases/inspect`
first. A new optional `DownloadHandler.list_files(release_data)` hook
returns the release's
   files without downloading:
- **AudiobookBay** reads the torrent file table off the detail page it
already fetches (the
page is now cached for 120 s, so inspect + download cost ABB one
request).
- **Prowlarr** parses `info.files` from the `.torrent` it already
fetches (the existing 120 s
torrent-fetch cache is reused). Magnet-only and usenet releases report
"can't inspect".
   - Other sources default to `None`.
2. **Review** – if the plan contains more than one book, the Find
Releases modal swaps the list
for a review panel: one row per book with editable title / series
position / year, expandable
file lists, non-book sidecars (`.txt`, covers) shown as ignored, a
"Treat as a single book"
switch, and **Download N books**. Single-book releases queue
immediately, exactly as before.
3. **File** – the approved plan travels with the task
(`DownloadTask.book_plan`, retry-safe) and
post-processing files each book through the existing transfer code, one
book at a time
(`dataclasses.replace(task, title=…, series_position=…, year=…)`), so
organize/rename
templates, part numbering (now scoped per book), hardlinks, torrent
copy-preserve and usenet
   handling are unchanged. Status reads `Complete (N books, M files)`.
4. **Fallback** – when a release can't be inspected the user gets a
toast, and a small
"Multi-book pack" toggle in the modal header forces a heuristic split
(subfolder = book, or
   one book per file when the file names carry series positions).

Planning lives in `shelfmark/download/postprocess/packs.py` and is
shared by the inspect endpoint
and post-processing, so what the user approved is what gets filed. The
name parser strips
`Book 3 -`, `03 -`, `1.0 -`, `3.`, `[03]`, `#3`, a leading series name,
labels like
"An Expanse Novella -", repeated titles (`Gods of Risk 2.5 - Gods of
Risk`) and a trailing
`(Year)`; author and series name come from the book that was searched,
and the searched book's
own series position is never applied to its siblings.

### Files

- `shelfmark/download/postprocess/packs.py` (new) –
`PackFile/PackBook/PackPlan`, `plan_pack`,
`parse_pack_book_name`, `group_files_into_books`, `match_plan_to_files`
- `shelfmark/core/release_inspect_routes.py` (new) – `POST
/api/releases/inspect`
- `shelfmark/release_sources/__init__.py` – `DownloadHandler.list_files`
hook
- `shelfmark/release_sources/audiobookbay/{scraper,handler}.py` –
detail-page cache,
  `extract_file_list`, `list_files`
- `shelfmark/release_sources/prowlarr/handler.py`,
`download/clients/torrent_utils.py` –
  `extract_file_list_from_torrent`, `list_files`
- `shelfmark/core/models.py`, `download/orchestrator.py` – `multi_book`
/ `book_plan` fields,
  queue + retry serialization
- `shelfmark/download/postprocess/transfer.py`, `pipeline.py`,
`outputs/folder.py` – per-book
  transfer branch and status message
- `src/frontend`: `components/PackReviewPanel.tsx` (new),
`ReleaseModal.tsx`, `App.tsx`,
`services/api.ts`, `types/index.ts`, `utils/releasePayload.ts` (payload
builder moved out of
  `App.tsx`), `utils/packReview.ts`
- `docs/dev/release-sources-plugin-guide.md` – documents the
`list_files` hook

### Out of scope (follow-ups)

- Listing files from an NZB (Shelfmark already fetches the bytes; `<file
subject>` names are noisy)
- Inspecting magnet links via qBittorrent's files API after a paused add
- BookLore / email outputs (they ignore `book_plan`; noted in code)
- The combined ebook + audiobook flow

### Testing

**Automated** (`make checks`, `make python-test`, `make frontend-test`
all green; the only
failures on my machine are the pre-existing
`tests/config/test_entrypoint_permissions.py` cases,
which need bash ≥ 4 and fail identically on `main` under macOS bash
3.2):

- `tests/download/test_packs.py` – name parsing (markers, series name,
novella labels, repeated
titles, bare numeric titles like `1984`), nested / flat / mixed /
deeper-nested packs, single
wrapping folder not treated as a pack, plan-to-disk matching with
basename fallback
- `tests/core/test_processing_packs.py` – full `post_process_download`
runs on a real temp
filesystem: approved plan files each book under its own
`{Author}/{Title}`, heuristic split
of a nested pack, searched book's series position does not leak,
multi-file book inside a pack
keeps `- 01/- 02` per book, hardlinked torrent pack leaves the seeding
tree intact, no pack
fields ⇒ behaviour unchanged, single group degrades to the searched
title, status message
- `tests/core/test_release_inspect_routes.py` – plan response,
not-inspectable, handler errors
  never 500, unknown source / missing `source_id` ⇒ 400, login required
- `tests/audiobookbay/test_file_list.py` – file-table scraping from real
ABB markup (multi-file
and single-file pages), handler host validation, one page fetch shared
by magnet + file list
- `tests/prowlarr/test_torrent_file_list.py` – multi-file / single-file
`.torrent` parsing,
  handler behaviour for torrent URL vs magnet vs usenet vs cache miss
- `tests/download/test_orchestrator_pack_fields.py` – queue-time parsing
and retry round-trip
- Frontend: `releasePayload.test.ts`, `packReview.test.ts` (vitest)

**Manual, on a real deployment** (arm64 image built from this branch,
run as a side container
next to production with the same qBittorrent / Audiobookshelf setup,
`FILE_ORGANIZATION_AUDIOBOOK=organize`,
hardlinks on):

- AudiobookBay "The Expanse Complete 2.0" (7.87 GB, 36 files): clicking
download opened the review
panel in ~1 s showing **18 books · 18 files · 18 files ignored** (the
`.txt` sidecars), with
series positions 0.1–9.5 and years parsed from the file names; novella
labels stripped
("The Churn", "The Butcher of Anderson Station"). Editing a title in the
panel works.
Confirming queued one task; the magnet resolved from the cached page in
~30 ms; after the
download the task reported `Complete (18 books, 18 files)`, 18 hardlinks
landed as
`audiobooks/James S. A. Corey/<Title>/<Title>.m4b`, the torrent kept
seeding, and
Audiobookshelf scanned each folder as its own book (title, author,
embedded chapters).
- A second pack ("Expanse [01 - 9.5]", `Title N - Title` naming) was
inspected to verify the
  repeated-title rule and the Back button, without downloading.
- Single-book releases still queue immediately with no extra UI.

.gitignore

@@ -236,6 +236,7 @@ pyrightconfig.json
 *.local.*
 AGENTS.md
 .claude/
+CLAUDE.md
 .nvmrc
 .playwright-mcp/
 frontend-dist/

docs/dev/release-sources-plugin-guide.md

@@ -276,6 +276,27 @@ class DownloadHandler(ABC):
         pass
 ```
 
+### Optional: Listing Files Before Download
+
+Some releases bundle several books (a whole-series torrent). Shelfmark inspects a
+release before queueing it so the user can review how it will be split into books.
+Override `list_files` when your source can enumerate a release's files without
+downloading it; the default returns `None`, which the UI reports as "can't inspect":
+
+```python
+from shelfmark.download.postprocess.packs import PackFile
+
+def list_files(self, release_data: dict[str, Any]) -> list[PackFile] | None:
+    """Return the release's files (release-relative paths + sizes), or None."""
+    torrent_bytes = ...  # e.g. fetch the .torrent, or scrape the indexer's detail page
+    return extract_file_list_from_torrent(torrent_bytes)  # from download.clients.torrent_utils
+```
+
+`release_data` is the same payload the frontend sends to `/api/releases/download`
+(`source_id`, `download_url`, `content_type`, `series_name`, ...). Built-in examples:
+Prowlarr parses the `.torrent` it already fetches (magnet-only releases return
+`None`), and AudiobookBay reads the file table off its detail page.
+
 ### Download Method Parameters
 
 | Parameter | Type | Description |

shelfmark/core/models.py

@@ -136,6 +136,12 @@ class DownloadTask:
         default_factory=dict
     )  # Per-output parameters (e.g. email recipient)
 
+    # Multi-book packs: one release holding several books. `book_plan` is the split the
+    # user approved before download (list of {title, series_position, year, files});
+    # `multi_book` asks post-processing to split heuristically when no plan exists.
+    multi_book: bool = False
+    book_plan: list[dict[str, Any]] | None = None
+
     # User association (multi-user support)
     user_id: int | None = None  # DB user ID who queued this download
     username: str | None = None  # Username for {User} template variable

shelfmark/core/release_inspect_routes.py

@@ -0,0 +1,102 @@
+"""Pre-download release inspection: list a release's files and plan a multi-book split."""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Any
+
+from flask import jsonify, request
+
+from shelfmark.core.logger import setup_logger
+from shelfmark.core.utils import is_audiobook
+from shelfmark.download.postprocess.packs import PackFile, PackPlan, plan_pack
+from shelfmark.download.postprocess.policy import (
+    get_supported_audiobook_formats,
+    get_supported_formats,
+)
+from shelfmark.release_sources import get_handler
+
+if TYPE_CHECKING:
+    from collections.abc import Callable
+
+    from flask import Flask, Response
+
+logger = setup_logger(__name__)
+
+_INSPECT_ERRORS = (OSError, RuntimeError, ValueError, TypeError, KeyError, AttributeError)
+NOT_INSPECTABLE_REASON = "This source cannot list the release's files before downloading"
+
+
+def _serialize_plan(plan: PackPlan) -> dict[str, Any]:
+    return {
+        "is_pack": plan.is_pack,
+        "ignored": plan.ignored,
+        "books": [
+            {
+                "title": book.title,
+                "series_position": book.series_position,
+                "year": book.year,
+                "files": book.files,
+            }
+            for book in plan.books
+        ],
+    }
+
+
+def inspect_release(data: dict[str, Any]) -> dict[str, Any]:
+    """Build the inspect response for a release payload (same shape as a download)."""
+    source = str(data["source"])
+    handler = get_handler(source)
+    try:
+        files: list[PackFile] | None = handler.list_files(data)
+    except _INSPECT_ERRORS as exc:
+        logger.warning(
+            "Could not list files for %s release %s: %s", source, data.get("source_id"), exc
+        )
+        return {"inspected": False, "reason": str(exc), "files": [], "plan": None}
+
+    if files is None:
+        return {"inspected": False, "reason": NOT_INSPECTABLE_REASON, "files": [], "plan": None}
+
+    content_type = data.get("content_type")
+    supported = (
+        get_supported_audiobook_formats()
+        if is_audiobook(content_type if isinstance(content_type, str) else None)
+        else get_supported_formats()
+    )
+    series_name = data.get("series_name")
+    author_name = data.get("author")
+    plan = plan_pack(
+        files,
+        supported_extensions=set(supported),
+        series_name=series_name if isinstance(series_name, str) else None,
+        author_name=author_name if isinstance(author_name, str) else None,
+    )
+    return {
+        "inspected": True,
+        "reason": None,
+        "files": [{"path": f.path, "size": f.size} for f in files],
+        "plan": _serialize_plan(plan),
+    }
+
+
+def register_release_inspect_routes(
+    app: Flask,
+    login_required: Callable[..., Any],
+) -> None:
+    """Register POST /api/releases/inspect."""
+
+    @app.route("/api/releases/inspect", methods=["POST"])
+    @login_required
+    def api_inspect_release() -> Response | tuple[Response, int]:
+        data = request.get_json(silent=True)
+        if not isinstance(data, dict):
+            return jsonify({"error": "No data provided"}), 400
+        if not data.get("source_id"):
+            return jsonify({"error": "source_id is required"}), 400
+        if not data.get("source"):
+            return jsonify({"error": "source is required"}), 400
+        try:
+            get_handler(str(data["source"]))
+        except ValueError as exc:
+            return jsonify({"error": str(exc)}), 400
+        return jsonify(inspect_release(data))

shelfmark/download/clients/torrent_utils.py

@@ -17,6 +17,7 @@ from shelfmark.core.config import config
 from shelfmark.core.logger import setup_logger
 from shelfmark.core.utils import normalize_http_url
 from shelfmark.download.network import get_ssl_verify
+from shelfmark.download.postprocess.packs import PackFile
 
 logger = setup_logger(__name__)
 
@@ -433,6 +434,56 @@ def extract_info_hash_from_torrent(torrent_data: bytes) -> str | None:
         return None
 
 
+def _decode_torrent_text(value: object) -> str | None:
+    if isinstance(value, bytes):
+        return value.decode("utf-8", errors="replace")
+    if isinstance(value, str):
+        return value
+    return None
+
+
+def extract_file_list_from_torrent(torrent_data: bytes) -> list[PackFile] | None:
+    """List the files a .torrent describes, release-relative, without downloading it.
+
+    Multi-file torrents nest every path under the torrent name (which becomes the
+    client's save folder); single-file torrents are just the named file.
+    """
+    try:
+        decoded, _ = bencode_decode(torrent_data)
+    except _TORRENT_PARSE_ERRORS as e:
+        logger.debug("Failed to parse torrent file list: %s", e)
+        return None
+    if not isinstance(decoded, dict):
+        return None
+    info = decoded.get(b"info")
+    if not isinstance(info, dict):
+        return None
+
+    name = _decode_torrent_text(info.get(b"name")) or ""
+    raw_files = info.get(b"files")
+    if not isinstance(raw_files, list):
+        length = info.get(b"length")
+        if not name:
+            return None
+        return [PackFile(name, length if isinstance(length, int) else None)]
+
+    files: list[PackFile] = []
+    for entry in raw_files:
+        if not isinstance(entry, dict):
+            continue
+        raw_path = entry.get(b"path")
+        if not isinstance(raw_path, list):
+            continue
+        segments = [seg for seg in (_decode_torrent_text(part) for part in raw_path) if seg]
+        if not segments:
+            continue
+        if name:
+            segments.insert(0, name)
+        length = entry.get(b"length")
+        files.append(PackFile("/".join(segments), length if isinstance(length, int) else None))
+    return files
+
+
 def extract_hash_from_magnet(magnet_url: str) -> str | None:
     """Extract info_hash from a magnet URL."""
     if not magnet_url.startswith("magnet:"):

shelfmark/download/orchestrator.py

@@ -265,6 +265,8 @@ def queue_release(
         series_position = release_data.get("series_position") or extra.get("series_position")
         subtitle = release_data.get("subtitle") or extra.get("subtitle")
         language = release_data.get("language") or extra.get("language")
+        multi_book = bool(release_data.get("multi_book") or extra.get("multi_book"))
+        book_plan = _normalize_book_plan(release_data.get("book_plan") or extra.get("book_plan"))
 
         books_output_mode = (
             str(config.get("BOOKS_OUTPUT_MODE", "folder", user_id=user_id) or "folder")
@@ -300,6 +302,8 @@ def queue_release(
             series_position=series_position,
             subtitle=subtitle,
             language=language,
+            multi_book=multi_book or book_plan is not None,
+            book_plan=book_plan,
             search_mode=search_mode,
             output_mode=output_mode,
             output_args=output_args,
@@ -408,6 +412,33 @@ def can_retry_download_task(
     return _has_staged_retry_source(task)
 
 
+def _normalize_book_plan(value: object) -> list[dict[str, Any]] | None:
+    """Keep only well-formed pack books: a title plus a non-empty list of file paths."""
+    if not isinstance(value, list):
+        return None
+    books: list[dict[str, Any]] = []
+    for entry in value:
+        if not isinstance(entry, dict):
+            continue
+        title = normalize_optional_text(entry.get("title"))
+        raw_files = entry.get("files")
+        if title is None or not isinstance(raw_files, list):
+            continue
+        files = [f for f in raw_files if isinstance(f, str) and f.strip()]
+        if not files:
+            continue
+        year = entry.get("year")
+        books.append(
+            {
+                "title": title,
+                "series_position": _optional_number(entry.get("series_position")),
+                "year": year if isinstance(year, int) and not isinstance(year, bool) else None,
+                "files": files,
+            }
+        )
+    return books or None
+
+
 def serialize_task_for_retry(task: DownloadTask) -> dict[str, Any]:
     """Serialize the task state needed for restart-safe retries."""
     raw_search_mode = getattr(task, "search_mode", None)
@@ -437,6 +468,8 @@ def serialize_task_for_retry(task: DownloadTask) -> dict[str, Any]:
         "subtitle": getattr(task, "subtitle", None),
         "language": getattr(task, "language", None),
         "search_mode": search_mode,
+        "multi_book": bool(getattr(task, "multi_book", False)),
+        "book_plan": _normalize_book_plan(getattr(task, "book_plan", None)),
         "output_mode": getattr(task, "output_mode", None),
         "output_args": dict(raw_output_args) if isinstance(raw_output_args, dict) else {},
         "user_id": getattr(task, "user_id", None),
@@ -495,6 +528,8 @@ def _restore_task_from_retry_payload(payload: object) -> DownloadTask | None:
         subtitle=normalize_optional_text(payload.get("subtitle")),
         language=normalize_optional_text(payload.get("language")),
         search_mode=search_mode,
+        multi_book=bool(payload.get("multi_book", False)),
+        book_plan=_normalize_book_plan(payload.get("book_plan")),
         output_mode=normalize_optional_text(payload.get("output_mode")),
         output_args=dict(output_args) if isinstance(output_args, dict) else {},
         user_id=normalize_positive_int(payload.get("user_id")),

shelfmark/download/outputs/folder.py

@@ -105,6 +105,7 @@ def process_folder_output(
         maybe_run_custom_script,
         prepare_output_files,
         record_step,
+        resolve_book_groups,
         transfer_book_files,
     )
 
@@ -260,7 +261,15 @@ def process_folder_output(
         prepared.cleanup_paths,
     )
 
-    message = "Complete" if len(final_paths) == 1 else f"Complete ({len(final_paths)} files)"
+    pack_groups = resolve_book_groups(
+        task, prepared.files, organization_mode=plan.organization_mode
+    )
+    if pack_groups is not None:
+        message = f"Complete ({len(pack_groups)} books, {len(final_paths)} files)"
+    elif len(final_paths) == 1:
+        message = "Complete"
+    else:
+        message = f"Complete ({len(final_paths)} files)"
     status_callback("complete", message)
 
     return str(final_paths[0])

shelfmark/download/postprocess/packs.py

@@ -0,0 +1,406 @@
+"""Multi-book ("pack") release planning.
+
+A pack is one release that contains several books: a whole-series torrent with one
+subfolder per book, or a flat folder of `Series 1.0 - Title.m4b` files. The same
+planning rules serve pre-download inspection (the file list comes from the release
+source) and post-processing (the file list comes from disk), so what the user
+approved in the modal is what gets filed.
+"""
+
+from __future__ import annotations
+
+import os
+import re
+from dataclasses import dataclass
+from pathlib import Path, PurePosixPath
+
+_YEAR_SUFFIX_RE = re.compile(r"\s*\(\s*(?P<year>\d{4})\s*\)\s*$")
+_SERIES_MARKER_RE = re.compile(
+    r"""
+    ^\s*
+    (?:
+        \[\s*\#?(?P<bracket>\d+(?:\.\d+)?)\s*\]     # [03] / [#3]
+      | \#(?P<hash>\d+(?:\.\d+)?)                    # #3
+      | book\.?\s*(?P<book>\d+(?:\.\d+)?)            # Book 3 / Book. 03
+      | (?P<plain>\d+(?:\.\d+)?)(?=[\s\-:.])         # 03 - / 1.0 - / 3.
+    )
+    \s*(?:[-:.]\s*)?
+    """,
+    re.IGNORECASE | re.VERBOSE,
+)
+_SEPARATOR_CHARS = " \t-_:."
+# "Gods of Risk 2.5 - Gods of Risk": the title repeated on both sides of the position.
+_REPEATED_TITLE_RE = re.compile(
+    r"^(?P<left>.+?)\s+(?P<position>\d+(?:\.\d+)?)\s*[-:\u2013]\s*(?P<right>.+)$"
+)
+_SERIES_LABEL_WORDS = r"(?:novella|novellas|short\s+story|short|story|novel)"
+# "Uncrowned Cradle, Book 7" / "Reaper Cradle, Volume 10" / "Wintersteel (Cradle, Book 8)":
+# an explicit word marks the position at the END of the name. A bare trailing number
+# is deliberately not matched — "Title - 02" is a chapter, not a series position.
+_TRAILING_MARKER_RE = re.compile(
+    r"""
+    [\s,\-:\u2013(]*
+    (?:book|volume|vol\.?)\s*\#?(?P<position>\d+(?:\.\d+)?)
+    \s*\)?\s*$
+    """,
+    re.IGNORECASE | re.VERBOSE,
+)
+# AudiobookBay renders a file inside a folder as "<folder> <file>" with no separator,
+# so a pack row reads "Author - Title Series, Book 1 Title Series, Book 1".
+_GLUED_FOLDER_RE = re.compile(
+    r"^(?P<prefix>.+?\s[-\u2013]\s)?(?P<core>.+?)\s+(?P=core)$", re.IGNORECASE
+)
+
+
+@dataclass(frozen=True)
+class PackFile:
+    """One file inside a release, path relative to the release root."""
+
+    path: str
+    size: int | None = None
+
+
+@dataclass(frozen=True)
+class PackBook:
+    """One book split out of a pack, files as release-relative paths."""
+
+    title: str
+    series_position: float | None
+    year: int | None
+    files: list[str]
+
+
+@dataclass(frozen=True)
+class PackPlan:
+    books: list[PackBook]
+    ignored: list[str]
+
+    @property
+    def is_pack(self) -> bool:
+        return len(self.books) > 1
+
+
+@dataclass(frozen=True)
+class BookGroup:
+    """One book's on-disk files, ready for transfer."""
+
+    title: str
+    series_position: float | None
+    year: int | None
+    files: list[Path]
+
+
+def _strip_series_name(name: str, series_name: str | None) -> str:
+    if not series_name:
+        return name
+    prefix = series_name.strip()
+    if not prefix or not name.lower().startswith(prefix.lower()):
+        return name
+    remainder = name[len(prefix) :]
+    if remainder and remainder[0].isalnum():
+        return name
+    return remainder.lstrip(_SEPARATOR_CHARS)
+
+
+def _strip_series_label(work: str, series_name: str | None) -> str:
+    """Drop a leading "An <Series> Novella - " style label that some packs prepend."""
+    if not series_name:
+        return work
+    # "The Expanse" is labelled "An Expanse Novella", so match without the article.
+    core = re.sub(r"^(?:the|an?)\s+", "", series_name.strip(), flags=re.IGNORECASE)
+    if not core:
+        return work
+    pattern = re.compile(
+        rf"^(?:an?\s+|the\s+)?{re.escape(core)}\s+{_SERIES_LABEL_WORDS}\s*[-:\u2013]\s*",
+        re.IGNORECASE,
+    )
+    return pattern.sub("", work, count=1)
+
+
+def _collapse_glued_folder(name: str) -> str:
+    match = _GLUED_FOLDER_RE.match(name)
+    if not match:
+        return name
+    prefix = match.group("prefix") or ""
+    core = match.group("core")
+    # "Author - X X" → "Author - X" (the folder carried the author, the file did not).
+    return (prefix + core).strip()
+
+
+def _strip_author_name(name: str, author_name: str | None) -> str:
+    """Drop a leading "Author - " (packs are often filed as `Author - Title`)."""
+    if not author_name:
+        return name
+    prefix = author_name.strip()
+    if not prefix or not name.lower().startswith(prefix.lower()):
+        return name
+    remainder = name[len(prefix) :]
+    stripped = remainder.lstrip(_SEPARATOR_CHARS + "\u2013")
+    if stripped == remainder:  # no separator after the author: part of the title
+        return name
+    return stripped
+
+
+def _strip_trailing_series_name(work: str, series_name: str | None) -> str:
+    """Drop a trailing series name left behind by a trailing position marker."""
+    if not series_name:
+        return work
+    suffix = series_name.strip()
+    if not suffix or not work.lower().endswith(suffix.lower()):
+        return work
+    remainder = work[: -len(suffix)]
+    stripped = remainder.rstrip(_SEPARATOR_CHARS + ",(\u2013")
+    if not stripped or stripped == remainder:
+        return work
+    return stripped
+
+
+def parse_pack_book_name(
+    name: str, *, series_name: str | None, author_name: str | None = None
+) -> tuple[str, float | None, int | None]:
+    """Split a book folder/file-stem name into (title, series position, year).
+
+    Strips a leading series name, a leading position marker (`Book 3 - `, `03 - `,
+    `1.0 - `, `3. `, `[03] `, `#3 `) and a trailing `(YYYY)`. Also understands a
+    trailing marker (`Title Series, Book 3`, `Title (Series, Volume 3)`), a leading
+    `Author - `, and AudiobookBay's glued `<folder> <file>` names. Returns the name
+    unchanged with no position/year when nothing would be left of the title.
+    """
+    work = _collapse_glued_folder(name.strip())
+    work = _strip_author_name(work, author_name)
+    work = _strip_series_name(work, series_name)
+
+    year: int | None = None
+    year_match = _YEAR_SUFFIX_RE.search(work)
+    if year_match:
+        year = int(year_match.group("year"))
+        work = work[: year_match.start()]
+
+    position: float | None = None
+    repeated = _REPEATED_TITLE_RE.match(work.strip())
+    if (
+        repeated
+        and repeated.group("left").strip().lower() == repeated.group("right").strip().lower()
+    ):
+        return repeated.group("right").strip(), float(repeated.group("position")), year
+
+    marker = _SERIES_MARKER_RE.match(work)
+    if marker:
+        raw = (
+            marker.group("bracket")
+            or marker.group("hash")
+            or marker.group("book")
+            or marker.group("plain")
+        )
+        position = float(raw)
+        work = work[marker.end() :]
+    else:
+        trailing = _TRAILING_MARKER_RE.search(work)
+        if trailing and trailing.start() > 0:
+            position = float(trailing.group("position"))
+            work = _strip_trailing_series_name(work[: trailing.start()], series_name)
+
+    work = _strip_series_label(work, series_name)
+    title = work.strip().strip(_SEPARATOR_CHARS).strip()
+    if not title:
+        return name, None, None
+    return title, position, year
+
+
+def _book_from_name(
+    name: str, files: list[str], series_name: str | None, author_name: str | None = None
+) -> PackBook:
+    title, position, year = parse_pack_book_name(
+        name, series_name=series_name, author_name=author_name
+    )
+    return PackBook(title=title, series_position=position, year=year, files=files)
+
+
+def _common_root_parts(paths: list[PurePosixPath]) -> tuple[str, ...]:
+    parents = [p.parent.parts for p in paths]
+    common: list[str] = []
+    for parts in zip(*parents, strict=False):
+        if len(set(parts)) != 1:
+            break
+        common.append(parts[0])
+    return tuple(common)
+
+
+def plan_pack(
+    files: list[PackFile],
+    *,
+    supported_extensions: set[str],
+    series_name: str | None,
+    author_name: str | None = None,
+    root_depth: int | None = None,
+) -> PackPlan:
+    """Group a release's file list into books.
+
+    Files in a subfolder (relative to the common root) group by that subfolder. Files
+    directly in the root split one-book-per-file only when at least two of them carry
+    a series position in their names; otherwise they are one book (a chaptered
+    audiobook, e.g. `01.mp3`, `02.mp3`). `root_depth` fixes how many leading path
+    components form the root instead of deriving it from the files' common parent.
+    """
+    supported = {ext.lower().lstrip(".") for ext in supported_extensions}
+    book_files: list[PurePosixPath] = []
+    ignored: list[str] = []
+    for pack_file in files:
+        rel = PurePosixPath(pack_file.path.replace("\\", "/").lstrip("./"))
+        if rel.suffix.lower().lstrip(".") in supported:
+            book_files.append(rel)
+        else:
+            ignored.append(pack_file.path)
+
+    if not book_files:
+        return PackPlan(books=[], ignored=ignored)
+
+    root_parts = (
+        _common_root_parts(book_files) if root_depth is None else book_files[0].parts[:root_depth]
+    )
+    depth = len(root_parts)
+
+    root_files: list[PurePosixPath] = []
+    folders: dict[str, list[str]] = {}
+    for rel in book_files:
+        remainder = rel.parts[depth:]
+        if len(remainder) > 1:
+            folders.setdefault(remainder[0], []).append(str(rel))
+        else:
+            root_files.append(rel)
+
+    books: list[PackBook] = []
+    if root_files:
+        parsed = [
+            parse_pack_book_name(f.stem, series_name=series_name, author_name=author_name)
+            for f in root_files
+        ]
+        positions = {p[1] for p in parsed if p[1] is not None}
+        if len(positions) >= 2:
+            books.extend(
+                PackBook(title=title, series_position=position, year=year, files=[str(f)])
+                for f, (title, position, year) in zip(root_files, parsed, strict=True)
+            )
+        elif len(root_files) == 1:
+            books.append(
+                _book_from_name(root_files[0].stem, [str(root_files[0])], series_name, author_name)
+            )
+        else:
+            group_name = root_parts[-1] if root_parts else ""
+            books.append(
+                _book_from_name(group_name, [str(f) for f in root_files], series_name, author_name)
+            )
+
+    books.extend(
+        _book_from_name(folder, paths, series_name, author_name)
+        for folder, paths in folders.items()
+    )
+    return PackPlan(books=books, ignored=ignored)
+
+
+def _relative_paths(
+    book_files: list[Path], root: Path | None = None
+) -> tuple[Path, dict[Path, str]]:
+    if root is None:
+        root = Path(os.path.commonpath([str(f.parent) for f in book_files]))
+    return root, {f: f.relative_to(root).as_posix() for f in book_files}
+
+
+def group_files_into_books(
+    book_files: list[Path],
+    *,
+    series_name: str | None,
+    author_name: str | None = None,
+    root: Path | None = None,
+) -> list[BookGroup]:
+    """Heuristically split on-disk files into books (see `plan_pack`).
+
+    `root` pins the release root when grouping a subset of a larger file set.
+    """
+    if not book_files:
+        return []
+    _root, rel_by_path = _relative_paths(book_files, root)
+    path_by_rel = {rel: path for path, rel in rel_by_path.items()}
+    extensions = {f.suffix.lower().lstrip(".") for f in book_files}
+    plan = plan_pack(
+        [PackFile(rel) for rel in rel_by_path.values()],
+        supported_extensions=extensions,
+        series_name=series_name,
+        author_name=author_name,
+        root_depth=None if root is None else 0,
+    )
+    return [
+        BookGroup(
+            title=book.title,
+            series_position=book.series_position,
+            year=book.year,
+            files=[path_by_rel[rel] for rel in book.files],
+        )
+        for book in plan.books
+    ]
+
+
+def match_plan_to_files(
+    plan: list[PackBook],
+    book_files: list[Path],
+    *,
+    series_name: str | None = None,
+    author_name: str | None = None,
+) -> list[BookGroup]:
+    """Apply an approved plan to on-disk files.
+
+    Files match by release-relative path first, then by basename (archive extraction
+    and client save paths can shift the root), then by the on-disk basename being a
+    suffix of the planned name (sources that glue folder and file names together).
+    Book files the plan does not mention fall back to heuristic grouping so nothing
+    is silently dropped.
+    """
+    if not book_files:
+        return []
+    root, rel_by_path = _relative_paths(book_files)
+    by_rel = {rel: path for path, rel in rel_by_path.items()}
+    by_name: dict[str, list[Path]] = {}
+    for path in book_files:
+        by_name.setdefault(path.name, []).append(path)
+
+    claimed: set[Path] = set()
+    groups: list[BookGroup] = []
+    for book in plan:
+        matched: list[Path] = []
+        for wanted in book.files:
+            wanted_rel = wanted.replace("\\", "/").lstrip("./")
+            candidate = by_rel.get(wanted_rel)
+            if candidate is None:
+                candidates = [
+                    p for p in by_name.get(PurePosixPath(wanted_rel).name, []) if p not in claimed
+                ]
+                candidate = candidates[0] if candidates else None
+            if candidate is None:
+                wanted_name = PurePosixPath(wanted_rel).name.lower()
+                candidates = [
+                    p
+                    for p in book_files
+                    if p not in claimed and wanted_name.endswith(p.name.lower())
+                ]
+                candidate = candidates[0] if len(candidates) == 1 else None
+            if candidate is not None and candidate not in claimed:
+                claimed.add(candidate)
+                matched.append(candidate)
+        if matched:
+            groups.append(
+                BookGroup(
+                    title=book.title,
+                    series_position=book.series_position,
+                    year=book.year,
+                    files=matched,
+                )
+            )
+
+    unmatched = [p for p in book_files if p not in claimed]
+    if unmatched:
+        groups.extend(
+            group_files_into_books(
+                unmatched, series_name=series_name, author_name=author_name, root=root
+            )
+        )
+    return groups

shelfmark/download/postprocess/pipeline.py

@@ -40,6 +40,7 @@ from .transfer import (
     build_metadata_dict,
     is_torrent_source,
     process_directory,
+    resolve_book_groups,
     resolve_hardlink_source,
     should_hardlink,
     transfer_book_files,
@@ -80,6 +81,7 @@ __all__ = [
     "process_directory",
     "record_step",
     "resolve_custom_script_target",
+    "resolve_book_groups",
     "resolve_hardlink_source",
     "run_custom_script",
     "safe_cleanup_path",

shelfmark/download/postprocess/transfer.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import dataclasses
 import os
 from pathlib import Path
 from typing import TYPE_CHECKING
@@ -26,6 +27,7 @@ from shelfmark.download.fs import (
 )
 from shelfmark.download.postprocess.policy import get_file_organization, get_template
 
+from .packs import BookGroup, PackBook, group_files_into_books, match_plan_to_files
 from .scan import collect_directory_files, scan_directory_tree
 from .types import TransferPlan
 from .workspace import safe_cleanup_path
@@ -196,6 +198,19 @@ def transfer_book_files(
 
     is_audiobook = check_audiobook(task.content_type)
     organization_mode = organization_mode or get_file_organization(is_audiobook=is_audiobook)
+
+    groups = resolve_book_groups(task, book_files, organization_mode=organization_mode)
+    if groups is not None:
+        return _transfer_book_groups(
+            groups,
+            destination,
+            task,
+            use_hardlink=use_hardlink,
+            is_torrent=is_torrent,
+            preserve_source=preserve_source,
+            organization_mode=organization_mode,
+        )
+
     max_attempts = _max_attempts_for_batch(len(book_files))
 
     final_paths: list[Path] = []
@@ -299,6 +314,101 @@ def transfer_book_files(
     return final_paths, None, op_counts
 
 
+def resolve_book_groups(
+    task: DownloadTask,
+    book_files: list[Path],
+    *,
+    organization_mode: str,
+) -> list[BookGroup] | None:
+    """Split a multi-book pack into per-book groups, or None to file as one book.
+
+    An approved `book_plan` wins; a bare `multi_book` flag falls back to heuristic
+    grouping. Organization `none` keeps files as-is, and a split that yields a single
+    group is not a pack at all.
+    """
+    if organization_mode == "none" or not (task.book_plan or task.multi_book):
+        return None
+    if task.book_plan:
+        plan = [
+            PackBook(
+                title=str(entry.get("title") or ""),
+                series_position=entry.get("series_position"),
+                year=entry.get("year"),
+                files=list(entry.get("files") or []),
+            )
+            for entry in task.book_plan
+            if isinstance(entry, dict)
+        ]
+        groups = match_plan_to_files(
+            plan, book_files, series_name=task.series_name, author_name=task.author
+        )
+    else:
+        groups = group_files_into_books(
+            book_files, series_name=task.series_name, author_name=task.author
+        )
+    return groups if len(groups) > 1 else None
+
+
+def _transfer_book_groups(
+    groups: list[BookGroup],
+    destination: Path,
+    task: DownloadTask,
+    *,
+    use_hardlink: bool,
+    is_torrent: bool,
+    preserve_source: bool,
+    organization_mode: str,
+) -> tuple[list[Path], str | None, dict[str, int]]:
+    """Transfer each book of a pack through the normal single-book path.
+
+    Each book gets an isolated task copy (the single-file path mutates `task.format`)
+    carrying its own title, position and year; the searched book's position must not
+    leak onto its siblings, while author and series name apply to all of them.
+    """
+    all_paths: list[Path] = []
+    totals: dict[str, int] = {"hardlink": 0, "copy": 0, "move": 0}
+    errors: list[str] = []
+
+    for group in groups:
+        book_task = dataclasses.replace(
+            task,
+            title=group.title or task.title,
+            year=str(group.year) if group.year is not None else None,
+            subtitle=None,
+            series_position=group.series_position,
+            multi_book=False,
+            book_plan=None,
+        )
+        paths, error, op_counts = transfer_book_files(
+            group.files,
+            destination,
+            book_task,
+            use_hardlink=use_hardlink,
+            is_torrent=is_torrent,
+            preserve_source=preserve_source,
+            organization_mode=organization_mode,
+            source_root=group.files[0].parent,
+        )
+        for op, count in op_counts.items():
+            totals[op] = totals.get(op, 0) + count
+        if error:
+            errors.append(f"{group.title}: {error}")
+            logger.warning("Task %s: pack book %r failed: %s", task.task_id, group.title, error)
+            continue
+        all_paths.extend(paths)
+
+    if not all_paths:
+        return [], "; ".join(errors) or "No book files found", totals
+    if errors:
+        logger.warning(
+            "Task %s: pack filed with %d failed book(s): %s",
+            task.task_id,
+            len(errors),
+            "; ".join(errors),
+        )
+    return all_paths, None, totals
+
+
 def process_directory(
     directory: Path,
     ingest_dir: Path,

shelfmark/main.py

@@ -62,6 +62,7 @@ from shelfmark.core.notifications import (
     notify_user,
 )
 from shelfmark.core.prefix_middleware import PrefixMiddleware
+from shelfmark.core.release_inspect_routes import register_release_inspect_routes
 from shelfmark.core.request_helpers import (
     coerce_bool,
     emit_ws_event,
@@ -1024,6 +1025,9 @@ def _serialize_release(release: Release) -> dict:
     return result
 
 
+register_release_inspect_routes(app, login_required)
+
+
 @app.route("/api/releases/download", methods=["POST"])
 @login_required
 def api_download_release() -> Response | tuple[Response, int]:

shelfmark/release_sources/__init__.py

@@ -13,6 +13,7 @@ if TYPE_CHECKING:
 
     from shelfmark.core.models import DownloadTask
     from shelfmark.core.search_plan import ReleaseSearchPlan
+    from shelfmark.download.postprocess.packs import PackFile
 
 from shelfmark.metadata_providers import BookMetadata
 
@@ -400,6 +401,14 @@ class DownloadHandler(ABC):
         """Return private queue-time fields needed for restart-safe retry."""
         return {}
 
+    def list_files(self, release_data: dict[str, Any]) -> list[PackFile] | None:
+        """Return the release's file list without downloading it.
+
+        Lets the UI review a multi-book pack before queueing. Return None when the
+        source cannot know the files ahead of time (magnet links, usenet, ...).
+        """
+        return None
+
     @abstractmethod
     def cancel(self, task_id: str) -> bool:
         """Cancel an in-progress download."""

shelfmark/release_sources/audiobookbay/handler.py

@@ -1,6 +1,6 @@
 """AudiobookBay download handler - resolves magnet links and uses shared client lifecycle."""
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
 from urllib.parse import urlparse
 
 from shelfmark.core.config import config
@@ -22,6 +22,7 @@ if TYPE_CHECKING:
     from collections.abc import Callable
 
     from shelfmark.core.models import DownloadTask
+    from shelfmark.download.postprocess.packs import PackFile
 
 logger = setup_logger(__name__)
 DEFAULT_ABB_HOSTNAME = "audiobookbay.lu"
@@ -68,6 +69,19 @@ class AudiobookBayHandler(ExternalClientHandler):
             return task_id
         return None
 
+    def list_files(self, release_data: dict[str, Any]) -> list[PackFile] | None:
+        """Read the torrent's file list off the detail page, without downloading."""
+        raw_url = release_data.get("download_url") or release_data.get("source_url")
+        detail_url = raw_url.strip() if isinstance(raw_url, str) else ""
+        hostname = _resolve_allowed_detail_hostname()
+        if not detail_url or not _detail_url_matches_host(detail_url, hostname):
+            logger.debug("Cannot list files for AudiobookBay release without a valid detail URL")
+            return None
+        detail_html = scraper.fetch_detail_html(detail_url, hostname)
+        if not detail_html:
+            return None
+        return scraper.extract_file_list(detail_html)
+
     def _get_client(self, protocol: str) -> DownloadClient | None:
         """Compatibility shim so module-level patching still works in tests."""
         return get_client(protocol)

shelfmark/release_sources/audiobookbay/scraper.py

@@ -2,6 +2,7 @@
 
 import re
 import time
+from threading import Lock
 from urllib.parse import quote, quote_plus
 
 import requests
@@ -10,6 +11,7 @@ from bs4 import BeautifulSoup
 from shelfmark.core.config import config
 from shelfmark.core.logger import setup_logger
 from shelfmark.download import http as downloader
+from shelfmark.download.postprocess.packs import PackFile
 from shelfmark.release_sources.audiobookbay.utils import normalize_search_punctuation
 
 logger = setup_logger(__name__)
@@ -32,6 +34,13 @@ FIRST_PAGE_SESSION_REFRESH_ATTEMPTS = 2
 # Legacy search parameter used by older ABB flows
 LEGACY_CATEGORY_QUERY = "undefined%2Cundefined"
 
+# Detail pages are fetched once and shared by inspection (file list) and download
+# (magnet link) so a "review then download" round trip costs ABB a single request.
+DETAIL_PAGE_CACHE_TTL_SECONDS = 120.0
+DETAIL_PAGE_CACHE_MAX_ENTRIES = 8
+_detail_page_cache: dict[str, tuple[float, str]] = {}
+_detail_page_cache_lock = Lock()
+
 # Precompiled patterns used while parsing result cards
 LANGUAGE_PATTERN = re.compile(r"Language:\s*([A-Za-z]+)")
 POSTED_PATTERN = re.compile(r"Posted:\s*(\d+\s+[A-Za-z]+\s+\d{4})")
@@ -39,6 +48,11 @@ FORMAT_PATTERN = re.compile(r"Format:\s*([A-Za-z0-9]+)")
 BITRATE_PATTERN = re.compile(r"Bitrate:\s*([\d]+\s*[A-Za-z/]+)")
 SIZE_PATTERN = re.compile(r"File Size:\s*([\d.]+)\s*([A-Za-z]+)")
 INFO_HASH_LABEL_PATTERN = re.compile(r"Info Hash", re.IGNORECASE)
+FILE_ROW_SIZE_PATTERN = re.compile(
+    r"^(?P<name>.+?)\s+(?P<size>\d+(?:\.\d+)?)\s*(?P<unit>Bytes?|KBs?|MBs?|GBs?|TBs?)$",
+    re.IGNORECASE,
+)
+_FILE_SIZE_MULTIPLIERS = {"b": 1, "k": 1024, "m": 1024**2, "g": 1024**3, "t": 1024**4}
 
 
 def _coerce_non_negative_float(value: object, default: float) -> float:
@@ -348,6 +362,98 @@ def search_audiobookbay(
     return results
 
 
+def _get_cached_detail_page(details_url: str) -> str | None:
+    with _detail_page_cache_lock:
+        entry = _detail_page_cache.get(details_url)
+        if entry is None:
+            return None
+        fetched_at, html = entry
+        if time.monotonic() - fetched_at > DETAIL_PAGE_CACHE_TTL_SECONDS:
+            del _detail_page_cache[details_url]
+            return None
+    return html
+
+
+def _store_cached_detail_page(details_url: str, html: str) -> None:
+    with _detail_page_cache_lock:
+        _detail_page_cache[details_url] = (time.monotonic(), html)
+        while len(_detail_page_cache) > DETAIL_PAGE_CACHE_MAX_ENTRIES:
+            oldest = min(_detail_page_cache, key=lambda key: _detail_page_cache[key][0])
+            del _detail_page_cache[oldest]
+
+
+def clear_detail_page_cache() -> None:
+    """Drop cached detail pages (used by tests)."""
+    with _detail_page_cache_lock:
+        _detail_page_cache.clear()
+
+
+def _fetch_detail_page_once(details_url: str, hostname: str) -> str:
+    session = requests.Session()
+    _bootstrap_abb_session(hostname, session, DETAIL_PAGE_RETRY_ATTEMPTS)
+    return _coerce_markup_to_html(
+        downloader.html_get_page(
+            details_url,
+            retry=DETAIL_PAGE_RETRY_ATTEMPTS,
+            use_bypasser=False,
+            allow_bypasser_fallback=False,
+            success_delay=0,
+            session=session,
+        )
+    )
+
+
+def fetch_detail_html(details_url: str, hostname: str = "audiobookbay.lu") -> str:
+    """Fetch a detail page (one retry with a fresh session), cached briefly per URL."""
+    cached = _get_cached_detail_page(details_url)
+    if cached is not None:
+        logger.debug("Reusing recently fetched detail page: %s", details_url)
+        return cached
+    detail_html = _fetch_detail_page_once(details_url, hostname)
+    if not detail_html:
+        detail_html = _fetch_detail_page_once(details_url, hostname)
+    if detail_html:
+        _store_cached_detail_page(details_url, detail_html)
+    return detail_html
+
+
+def _parse_file_row(text: str) -> PackFile | None:
+    match = FILE_ROW_SIZE_PATTERN.match(text.strip())
+    if not match:
+        return None
+    multiplier = _FILE_SIZE_MULTIPLIERS[match.group("unit")[0].lower()]
+    return PackFile(match.group("name"), int(float(match.group("size")) * multiplier))
+
+
+def extract_file_list(detail_html: str) -> list[PackFile] | None:
+    """Read the torrent file rows off a detail page.
+
+    ABB renders the torrent's file table as single-cell rows between the
+    "This is a Multifile Torrent" marker (absent for single-file torrents) and the
+    "Combined File Size" row. Returns None when the page has no such table.
+    """
+    soup = BeautifulSoup(detail_html, "html.parser")
+    rows: list[PackFile] = []
+    for row in soup.find_all("tr"):
+        cells = row.find_all("td")
+        if not cells:
+            continue
+        label = cells[0].get_text(" ", strip=True)
+        if label.lower().startswith("combined file size"):
+            return rows or None
+        if len(cells) != 1:
+            rows = []  # a two-column metadata row means we're not in the file table yet
+            continue
+        text = cells[0].get_text(" ", strip=True)
+        if "multifile torrent" in text.lower():
+            rows = []
+            continue
+        parsed = _parse_file_row(text)
+        if parsed is not None:
+            rows.append(parsed)
+    return None
+
+
 def extract_magnet_link(details_url: str, hostname: str = "audiobookbay.lu") -> str | None:
     """Extract info hash and trackers from book detail page, then construct magnet link.
 
@@ -360,35 +466,7 @@ def extract_magnet_link(details_url: str, hostname: str = "audiobookbay.lu") ->
 
     """
     try:
-        session = requests.Session()
+        detail_html = fetch_detail_html(details_url, hostname)
-        _bootstrap_abb_session(hostname, session, DETAIL_PAGE_RETRY_ATTEMPTS)
-
-        # Fetch detail page
-        detail_html = _coerce_markup_to_html(
-            downloader.html_get_page(
-                details_url,
-                retry=DETAIL_PAGE_RETRY_ATTEMPTS,
-                use_bypasser=False,
-                allow_bypasser_fallback=False,
-                success_delay=0,
-                session=session,
-            )
-        )
-
-        if not detail_html:
-            session = requests.Session()
-            _bootstrap_abb_session(hostname, session, DETAIL_PAGE_RETRY_ATTEMPTS)
-            detail_html = _coerce_markup_to_html(
-                downloader.html_get_page(
-                    details_url,
-                    retry=DETAIL_PAGE_RETRY_ATTEMPTS,
-                    use_bypasser=False,
-                    allow_bypasser_fallback=False,
-                    success_delay=0,
-                    session=session,
-                )
-            )
-
         if not detail_html:
             logger.warning("Failed to fetch details page")
             return None

shelfmark/release_sources/prowlarr/handler.py

@@ -28,6 +28,10 @@ from shelfmark.download.clients.base_handler import (
     DownloadRequest,
     ExternalClientHandler,
 )
+from shelfmark.download.clients.torrent_utils import (
+    extract_file_list_from_torrent,
+    extract_torrent_info,
+)
 from shelfmark.metadata_providers import BookMetadata
 from shelfmark.release_sources import register_handler
 from shelfmark.release_sources.prowlarr.api import IndexerSeedSettings, ProwlarrClient
@@ -38,12 +42,14 @@ from shelfmark.release_sources.prowlarr.utils import (
     coerce_int_like,
     get_preferred_download_url,
     get_protocol,
+    sanitize_download_url,
 )
 
 if TYPE_CHECKING:
     from collections.abc import Callable
 
     from shelfmark.core.models import DownloadTask
+    from shelfmark.download.postprocess.packs import PackFile
 
 logger = setup_logger(__name__)
 
@@ -127,6 +133,24 @@ class ProwlarrHandler(ExternalClientHandler):
 
         return settings.get(indexer_id)
 
+    def list_files(self, release_data: dict[str, Any]) -> list[PackFile] | None:
+        """List a cached torrent release's files from its .torrent, without downloading.
+
+        Magnet-only and usenet releases cannot be listed ahead of time.
+        """
+        source_id = str(release_data.get("source_id") or "")
+        prowlarr_result = get_release(source_id) if source_id else None
+        if not prowlarr_result or get_protocol(prowlarr_result) != "torrent":
+            return None
+        download_url = sanitize_download_url(str(prowlarr_result.get("downloadUrl") or "").strip())
+        if not download_url or download_url.startswith("magnet:"):
+            return None
+        expected_hash = str(prowlarr_result.get("infoHash") or "").strip() or None
+        info = extract_torrent_info(download_url, expected_hash=expected_hash)
+        if not info.torrent_data:
+            return None
+        return extract_file_list_from_torrent(info.torrent_data)
+
     def _get_client(self, protocol: str) -> DownloadClient | None:
         """Compatibility shim so module-level patching still works in tests."""
         return get_client(protocol)

src/frontend/src/App.tsx

@@ -58,7 +58,6 @@ import {
   isApiResponseError,
   updateSelfUser,
   setBookTargetState,
-  type DownloadReleasePayload,
 } from './services/api';
 import type {
   Book,
@@ -93,6 +92,7 @@ import { getEffectiveMetadataSort } from './utils/metadataSort';
 import { isRecord } from './utils/objectHelpers';
 import { policyTrace } from './utils/policyTrace';
 import { buildQueryTargets, getDefaultQueryTargetKey } from './utils/queryTargets';
+import { buildReleaseDownloadPayload, type ReleaseDownloadOptions } from './utils/releasePayload';
 import { applyRequestNoteToPayload } from './utils/requestConfirmation';
 import { bookFromRequestData } from './utils/requestFulfil';
 import {
@@ -219,6 +219,7 @@ type PendingOnBehalfDownload =
       release: Release;
       releaseContentType: ContentType;
       actingAsUser: ActingAsUserSelection;
+      options?: ReleaseDownloadOptions;
     }
   | {
       type: 'combined';
@@ -1072,41 +1073,6 @@ function App() {
     [],
   );
 
-  const buildReleaseDownloadPayload = useCallback(
-    (book: Book, release: Release, releaseContentType: ContentType): DownloadReleasePayload => {
-      const isManual = book.provider === 'manual';
-      const releasePreview =
-        typeof release.extra?.preview === 'string' ? release.extra.preview : undefined;
-      const releaseAuthor =
-        typeof release.extra?.author === 'string' ? release.extra.author : undefined;
-
-      return {
-        source: release.source,
-        source_id: release.source_id,
-        title: isManual ? release.title : book.title,
-        author: isManual ? releaseAuthor || '' : book.author,
-        year: book.year,
-        format: release.format,
-        size: release.size,
-        size_bytes: release.size_bytes,
-        download_url: release.download_url,
-        protocol: release.protocol,
-        indexer: release.indexer,
-        seeders: release.seeders,
-        extra: release.extra,
-        preview: isManual ? releasePreview || undefined : book.preview,
-        content_type: releaseContentType,
-        series_name: book.series_name,
-        series_position: book.series_position,
-        subtitle: book.subtitle,
-        // From the release, never the book: book.language is the provider's
-        // canonical edition, which would mislabel a translated release.
-        language: release.language ?? undefined,
-      };
-    },
-    [],
-  );
-
   // When downloading a book while browsing a Hardcover list the user owns,
   // automatically remove it from that list (fire-and-forget).
   const searchFieldLabelsRef = useRef(searchFieldLabels);
@@ -1214,12 +1180,13 @@ function App() {
       release: Release,
       releaseContentType: ContentType,
       onBehalfOfUserId?: number,
+      options?: ReleaseDownloadOptions,
     ): Promise<void> => {
       const requestStartedAtSeconds = Date.now() / 1000;
       try {
         trackRelease(book.id, release.source_id);
         await downloadRelease(
-          buildReleaseDownloadPayload(book, release, releaseContentType),
+          buildReleaseDownloadPayload(book, release, releaseContentType, options),
           onBehalfOfUserId,
         );
         await fetchStatus();
@@ -1301,7 +1268,6 @@ function App() {
       }
     },
     [
-      buildReleaseDownloadPayload,
       fetchStatus,
       openRequestConfirmation,
       refreshRequestPolicy,
@@ -1416,6 +1382,7 @@ function App() {
           effectivePendingOnBehalfDownload.release,
           effectivePendingOnBehalfDownload.releaseContentType,
           onBehalfOfUserId,
+          effectivePendingOnBehalfDownload.options,
         );
       }
       setPendingOnBehalfDownload(null);
@@ -1640,6 +1607,7 @@ function App() {
     book: Book,
     release: Release,
     releaseContentType: ContentType,
+    options?: ReleaseDownloadOptions,
   ) => {
     policyTrace('release.action:start', {
       bookId: book.id,
@@ -1655,11 +1623,12 @@ function App() {
         release,
         releaseContentType,
         actingAsUser: effectiveActingAsUser,
+        options,
       });
       return;
     }
 
-    await executeReleaseDownload(book, release, releaseContentType);
+    await executeReleaseDownload(book, release, releaseContentType, undefined, options);
   };
 
   const handleReleaseRequest = useCallback(

src/frontend/src/components/PackReviewPanel.tsx

@@ -0,0 +1,193 @@
+import { useState } from 'react';
+
+import type { PackBook, PackPlan, Release } from '../types';
+import {
+  describePackPlan,
+  parseSeriesPositionInput,
+  toBookPlanPayload,
+  updateReviewBook,
+} from '../utils/packReview';
+import { ToggleSwitch } from './shared/ToggleSwitch';
+
+interface PackReviewPanelProps {
+  release: Release;
+  plan: PackPlan;
+  books: PackBook[];
+  onChange: (books: PackBook[]) => void;
+  onBack: () => void;
+  /** `null` means "treat the whole release as one book". */
+  onConfirm: (books: PackBook[] | null) => Promise<void>;
+  isSubmitting: boolean;
+}
+
+const inputClassName =
+  'w-full rounded-md border border-(--border-muted) bg-(--bg) px-2 py-1 text-sm text-(--text) focus:border-emerald-500 focus:outline-none';
+
+export const PackReviewPanel = ({
+  release,
+  plan,
+  books,
+  onChange,
+  onBack,
+  onConfirm,
+  isSubmitting,
+}: PackReviewPanelProps) => {
+  const [singleBook, setSingleBook] = useState(false);
+  const [expandedFiles, setExpandedFiles] = useState<number | null>(null);
+  const [showIgnored, setShowIgnored] = useState(false);
+
+  const payloadBooks = toBookPlanPayload(books);
+  const canConfirm = !isSubmitting && (singleBook || payloadBooks.length > 0);
+  const confirmLabel = singleBook
+    ? 'Download as one book'
+    : `Download ${payloadBooks.length} ${payloadBooks.length === 1 ? 'book' : 'books'}`;
+
+  return (
+    <div className="flex flex-col gap-4 px-5 py-4" data-testid="pack-review-panel">
+      <div>
+        <h3 className="text-base font-semibold text-(--text)">
+          This release contains several books
+        </h3>
+        <p className="mt-1 text-sm text-zinc-500 dark:text-zinc-400">
+          <span className="font-medium text-(--text)">{release.title}</span> ·{' '}
+          {describePackPlan(books, plan.ignored)}
+        </p>
+        <p className="mt-1 text-xs text-zinc-500 dark:text-zinc-400">
+          Each book below is filed separately with its own title. Fix any titles before downloading
+          — the author and series come from the book you searched.
+        </p>
+      </div>
+
+      <div className="flex items-center justify-between rounded-lg border border-(--border-muted) px-3 py-2">
+        <div>
+          <p className="text-sm font-medium text-(--text)">Treat as a single book</p>
+          <p className="text-xs text-zinc-500 dark:text-zinc-400">
+            Use this if the split is wrong and the files are really one audiobook.
+          </p>
+        </div>
+        <ToggleSwitch
+          checked={singleBook}
+          onChange={setSingleBook}
+          color="emerald"
+          ariaLabel="Treat as a single book"
+          disabled={isSubmitting}
+        />
+      </div>
+
+      <div
+        className={`flex flex-col divide-y divide-zinc-200/60 dark:divide-zinc-800/60 ${
+          singleBook ? 'pointer-events-none opacity-40' : ''
+        }`}
+      >
+        <div className="grid grid-cols-[minmax(0,1fr)_72px_72px_80px] gap-2 pb-1 text-xs font-medium tracking-wide text-zinc-500 uppercase dark:text-zinc-400">
+          <span>Title</span>
+          <span>Series #</span>
+          <span>Year</span>
+          <span className="text-right">Files</span>
+        </div>
+        {books.map((book, index) => (
+          <div key={book.files[0] ?? index} className="py-2">
+            <div className="grid grid-cols-[minmax(0,1fr)_72px_72px_80px] items-center gap-2">
+              <input
+                type="text"
+                value={book.title}
+                onChange={(e) =>
+                  onChange(updateReviewBook(books, index, { title: e.target.value }))
+                }
+                aria-label={`Title for book ${index + 1}`}
+                className={inputClassName}
+                disabled={isSubmitting}
+              />
+              <input
+                type="text"
+                inputMode="decimal"
+                value={book.series_position ?? ''}
+                onChange={(e) =>
+                  onChange(
+                    updateReviewBook(books, index, {
+                      series_position: parseSeriesPositionInput(e.target.value),
+                    }),
+                  )
+                }
+                aria-label={`Series position for book ${index + 1}`}
+                className={inputClassName}
+                disabled={isSubmitting}
+              />
+              <input
+                type="text"
+                inputMode="numeric"
+                value={book.year ?? ''}
+                onChange={(e) => {
+                  const parsed = parseSeriesPositionInput(e.target.value);
+                  onChange(
+                    updateReviewBook(books, index, {
+                      year: parsed === null ? null : Math.trunc(parsed),
+                    }),
+                  );
+                }}
+                aria-label={`Year for book ${index + 1}`}
+                className={inputClassName}
+                disabled={isSubmitting}
+              />
+              <button
+                type="button"
+                onClick={() => setExpandedFiles(expandedFiles === index ? null : index)}
+                className="hover-surface rounded-md px-2 py-1 text-right text-sm text-zinc-500 transition-colors dark:text-zinc-400"
+                aria-expanded={expandedFiles === index}
+              >
+                {book.files.length} {book.files.length === 1 ? 'file' : 'files'}
+              </button>
+            </div>
+            {expandedFiles === index && (
+              <ul className="mt-2 max-h-40 overflow-y-auto rounded-md bg-(--bg-soft) px-3 py-2 font-mono text-xs break-all text-zinc-600 dark:text-zinc-300">
+                {book.files.map((file) => (
+                  <li key={file}>{file}</li>
+                ))}
+              </ul>
+            )}
+          </div>
+        ))}
+      </div>
+
+      {plan.ignored.length > 0 && (
+        <div>
+          <button
+            type="button"
+            onClick={() => setShowIgnored(!showIgnored)}
+            className="text-xs text-zinc-500 underline-offset-2 hover:underline dark:text-zinc-400"
+            aria-expanded={showIgnored}
+          >
+            {plan.ignored.length} {plan.ignored.length === 1 ? 'file' : 'files'} ignored (not a book
+            format)
+          </button>
+          {showIgnored && (
+            <ul className="mt-2 max-h-32 overflow-y-auto rounded-md bg-(--bg-soft) px-3 py-2 font-mono text-xs break-all text-zinc-600 dark:text-zinc-300">
+              {plan.ignored.map((file) => (
+                <li key={file}>{file}</li>
+              ))}
+            </ul>
+          )}
+        </div>
+      )}
+
+      <div className="flex items-center justify-end gap-3 border-t border-(--border-muted) pt-4">
+        <button
+          type="button"
+          onClick={onBack}
+          disabled={isSubmitting}
+          className="hover-surface rounded-lg px-3 py-1.5 text-sm font-medium text-(--text) transition-colors disabled:opacity-50"
+        >
+          &larr; Back
+        </button>
+        <button
+          type="button"
+          onClick={() => void onConfirm(singleBook ? null : payloadBooks)}
+          disabled={!canConfirm}
+          className="rounded-lg bg-emerald-600 px-4 py-1.5 text-sm font-medium text-white transition-colors hover:bg-emerald-700 disabled:cursor-not-allowed disabled:opacity-50"
+        >
+          {isSubmitting ? 'Queuing…' : confirmLabel}
+        </button>
+      </div>
+    </div>
+  );
+};

src/frontend/src/components/ReleaseModal.tsx

@@ -7,6 +7,7 @@ import { useReleaseSearchSession } from '../hooks/releaseModal/useReleaseSearchS
 import { useTabIndicator } from '../hooks/ui/useTabIndicator';
 import { useBodyScrollLock } from '../hooks/useBodyScrollLock';
 import { useEscapeKey } from '../hooks/useEscapeKey';
+import { inspectRelease } from '../services/api';
 import type {
   Book,
   Release,
@@ -18,6 +19,8 @@ import type {
   LeadingCellConfig,
   ContentType,
   RequestPolicyMode,
+  PackBook,
+  PackPlan,
 } from '../types';
 import { isMetadataBook } from '../types';
 import { bookSupportsTargets } from '../utils/bookTargetLoader';
@@ -29,7 +32,9 @@ import {
   buildLanguageNormalizer,
 } from '../utils/languageFilters';
 import { getNestedValue, toComparableText, toStringValue } from '../utils/objectHelpers';
+import { toBookPlanPayload } from '../utils/packReview';
 import { getReleaseFormats } from '../utils/releaseFormats';
+import { buildReleaseDownloadPayload, type ReleaseDownloadOptions } from '../utils/releasePayload';
 import {
   getBookTitleCandidates,
   getBookAuthorCandidates,
@@ -50,6 +55,7 @@ import { BookTargetDropdown } from './BookTargetDropdown';
 import { Dropdown } from './Dropdown';
 import { DropdownList } from './DropdownList';
 import { LanguageMultiSelect } from './LanguageMultiSelect';
+import { PackReviewPanel } from './PackReviewPanel';
 import { ReleaseCell } from './ReleaseCell';
 
 // Combined mode configuration for the ReleaseModal
@@ -140,7 +146,12 @@ const DEFAULT_COLUMN_CONFIG: ReleaseColumnConfig = {
 interface ReleaseModalProps {
   book: Book | null;
   onClose: () => void;
-  onDownload: (book: Book, release: Release, contentType: ContentType) => Promise<void>;
+  onDownload: (
+    book: Book,
+    release: Release,
+    contentType: ContentType,
+    options?: ReleaseDownloadOptions,
+  ) => Promise<void>;
   onRequestRelease?: (book: Book, release: Release, contentType: ContentType) => Promise<void>;
   onRequestBook?: (book: Book, contentType: ContentType) => Promise<void>;
   getPolicyModeForSource?: (source: string, contentType: ContentType) => RequestPolicyMode;
@@ -762,6 +773,15 @@ const ReleaseModalSession = ({
       : supportedFormats;
   const [isRequestingBook, setIsRequestingBook] = useState(false);
   const [selectedRelease, setSelectedRelease] = useState<Release | null>(null);
+  // Multi-book packs: `multiBook` is the manual header toggle (heuristic split for
+  // releases we can't inspect); `packReview` holds an inspected pack awaiting approval.
+  const [multiBook, setMultiBook] = useState(false);
+  const [packReview, setPackReview] = useState<{
+    release: Release;
+    plan: PackPlan;
+    books: PackBook[];
+  } | null>(null);
+  const [packSubmitting, setPackSubmitting] = useState(false);
   const isCombinedMode = combinedMode != null;
   const combinedPhase = combinedMode?.phase ?? null;
   const combinedStepLabel = combinedMode?.stepLabel ?? '';
@@ -1196,7 +1216,30 @@ const ReleaseModalSession = ({
 
       const mode = getReleaseActionMode(release);
       if (mode === 'download') {
-        await onDownload(book, release, contentType);
+        // Look at the release's files before queueing so a whole-series pack can be
+        // reviewed and filed as separate books instead of one mangled item.
+        let inspected = false;
+        let plan: PackPlan | null = null;
+        try {
+          const inspection = await inspectRelease(
+            buildReleaseDownloadPayload(book, release, contentType),
+          );
+          inspected = inspection.inspected;
+          plan = inspection.plan;
+        } catch (error) {
+          console.error('Release inspection failed:', error);
+        }
+        if (inspected && plan?.is_pack) {
+          setPackReview({ release, plan, books: plan.books });
+          return;
+        }
+        if (!inspected && !multiBook) {
+          onShowToast?.(
+            "Couldn't check this release's files before download. If it contains several books, turn on the multi-book pack toggle first.",
+            'info',
+          );
+        }
+        await onDownload(book, release, contentType, multiBook ? { multiBook: true } : {});
         handleClose();
         return;
       }
@@ -1215,9 +1258,32 @@ const ReleaseModalSession = ({
       onRequestRelease,
       contentType,
       handleClose,
+      multiBook,
+      onShowToast,
     ],
   );
 
+  const handlePackConfirm = useCallback(
+    async (books: PackBook[] | null): Promise<void> => {
+      if (!book || !packReview) {
+        return;
+      }
+      setPackSubmitting(true);
+      try {
+        await onDownload(
+          book,
+          packReview.release,
+          contentType,
+          books ? { multiBook: true, bookPlan: toBookPlanPayload(books) } : {},
+        );
+        handleClose();
+      } finally {
+        setPackSubmitting(false);
+      }
+    },
+    [book, packReview, onDownload, contentType, handleClose],
+  );
+
   const titleId = `release-modal-title-${book.id}`;
   const providerDisplay =
     book.provider_display_name ||
@@ -1720,6 +1786,37 @@ const ReleaseModalSession = ({
                   </div>
 
                   <div className="flex items-center gap-3 pr-1 pl-2">
+                    {/* Multi-book pack toggle (fallback for releases that can't be inspected) */}
+                    {!isCombinedMode && (
+                      <button
+                        type="button"
+                        onClick={() => setMultiBook((prev) => !prev)}
+                        className={`hover-surface relative rounded-full p-2.5 text-zinc-500 transition-colors dark:text-zinc-400 ${
+                          multiBook ? 'text-emerald-600 dark:text-emerald-400' : ''
+                        }`}
+                        aria-label="Multi-book pack"
+                        aria-pressed={multiBook}
+                        title="Multi-book pack: file each subfolder (or each file) as a separate book. Only needed when a release can't be inspected before download."
+                      >
+                        <svg
+                          className="h-4 w-4"
+                          fill="none"
+                          stroke="currentColor"
+                          viewBox="0 0 24 24"
+                          strokeWidth={1.5}
+                        >
+                          <path
+                            strokeLinecap="round"
+                            strokeLinejoin="round"
+                            d="M6.429 9.75 2.25 12l4.179 2.25m0-4.5 5.571 3 5.571-3m-11.142 0L2.25 7.5 12 2.25l9.75 5.25-4.179 2.25m0 0L21.75 12l-4.179 2.25m0 0 4.179 2.25L12 21.75 2.25 16.5l4.179-2.25m11.142 0-5.571 3-5.571-3"
+                          />
+                        </svg>
+                        {multiBook && (
+                          <span className="absolute top-1 right-1 h-2 w-2 rounded-full bg-emerald-500" />
+                        )}
+                      </button>
+                    )}
+
                     {/* Manual query button */}
                     <button
                       type="button"
@@ -2120,6 +2217,19 @@ const ReleaseModalSession = ({
             {/* Release list content */}
             <div className="min-h-[200px]">
               {(() => {
+                if (packReview) {
+                  return (
+                    <PackReviewPanel
+                      release={packReview.release}
+                      plan={packReview.plan}
+                      books={packReview.books}
+                      onChange={(books) => setPackReview({ ...packReview, books })}
+                      onBack={() => setPackReview(null)}
+                      onConfirm={handlePackConfirm}
+                      isSubmitting={packSubmitting}
+                    />
+                  );
+                }
                 if (sourcesLoading) {
                   return <ReleaseSkeleton />;
                 }

src/frontend/src/services/api.ts

@@ -12,6 +12,8 @@ import type {
   RequestSubmissionResult,
   MetadataProvidersResponse,
   MetadataSearchConfig,
+  PackBook,
+  InspectReleaseResponse,
 } from '../types';
 import type {
   ActionResult,
@@ -510,6 +512,18 @@ export type DownloadReleasePayload = {
   language?: string; // Release language code, for the {Language} naming variable
   search_author?: string;
   search_mode?: 'direct' | 'universal';
+  multi_book?: boolean; // Split a multi-book pack into one book per subfolder/file
+  book_plan?: PackBook[]; // The split the user approved before download
+};
+
+/** Inspect a release's file list before download (same body as downloadRelease). */
+export const inspectRelease = async (
+  release: DownloadReleasePayload,
+): Promise<InspectReleaseResponse> => {
+  return fetchJSON<InspectReleaseResponse>(`${API_BASE}/releases/inspect`, {
+    method: 'POST',
+    body: JSON.stringify(release),
+  });
 };
 
 export const downloadRelease = async (

src/frontend/src/tests/packReview.test.ts

@@ -0,0 +1,53 @@
+import { describe, it, expect } from 'vitest';
+
+import type { PackBook } from '../types';
+import {
+  describePackPlan,
+  parseSeriesPositionInput,
+  toBookPlanPayload,
+  updateReviewBook,
+} from '../utils/packReview';
+
+const books: PackBook[] = [
+  { title: 'Leviathan Wakes', series_position: 1, year: 2011, files: ['a.m4b'] },
+  { title: 'Caliban’s War', series_position: 2, year: 2012, files: ['b.m4b', 'b2.m4b'] },
+];
+
+describe('packReview.updateReviewBook', () => {
+  it('replaces one book without touching the others', () => {
+    const next = updateReviewBook(books, 1, { title: 'Caliban’s War (Unabridged)' });
+    expect(next[0]).toBe(books[0]);
+    expect(next[1]).toEqual({ ...books[1], title: 'Caliban’s War (Unabridged)' });
+    expect(books[1].title).toBe('Caliban’s War');
+  });
+});
+
+describe('packReview.parseSeriesPositionInput', () => {
+  it('accepts whole and fractional positions', () => {
+    expect(parseSeriesPositionInput('3')).toBe(3);
+    expect(parseSeriesPositionInput('2.5')).toBe(2.5);
+  });
+
+  it('treats blank or junk as no position', () => {
+    expect(parseSeriesPositionInput('')).toBeNull();
+    expect(parseSeriesPositionInput('abc')).toBeNull();
+  });
+});
+
+describe('packReview.toBookPlanPayload', () => {
+  it('trims titles, drops books without a title, and keeps file lists', () => {
+    const edited = updateReviewBook(books, 0, { title: '   ' });
+    expect(toBookPlanPayload(edited)).toEqual([
+      { title: 'Caliban’s War', series_position: 2, year: 2012, files: ['b.m4b', 'b2.m4b'] },
+    ]);
+  });
+});
+
+describe('packReview.describePackPlan', () => {
+  it('summarises books, files and ignored sidecars', () => {
+    expect(describePackPlan(books, ['a.txt', 'cover.jpg'])).toBe(
+      '2 books · 3 files · 2 files ignored',
+    );
+    expect(describePackPlan([books[0]], [])).toBe('1 book · 1 file');
+  });
+});

src/frontend/src/tests/releasePayload.test.ts

@@ -0,0 +1,69 @@
+import { describe, it, expect } from 'vitest';
+
+import type { Book, Release } from '../types';
+import { buildReleaseDownloadPayload } from '../utils/releasePayload';
+
+const book: Book = {
+  id: 'hc-1',
+  title: 'Drive',
+  author: 'James S. A. Corey',
+  year: '2012',
+  preview: 'https://img/drive.jpg',
+  series_name: 'The Expanse',
+  series_position: 2.6,
+  subtitle: 'An Expanse Short Story',
+  provider: 'hardcover',
+  provider_id: 'hc-1',
+  source: 'direct_download',
+};
+
+const release: Release = {
+  source: 'audiobookbay',
+  source_id: 'abb-1',
+  title: 'James S. A. Corey - The Expanse Complete 2.0',
+  format: 'm4b',
+  language: 'en',
+  download_url: 'https://audiobookbay.lu/abss/expanse/',
+};
+
+describe('buildReleaseDownloadPayload', () => {
+  it('describes the searched book and the chosen release', () => {
+    const payload = buildReleaseDownloadPayload(book, release, 'audiobook');
+    expect(payload).toMatchObject({
+      source: 'audiobookbay',
+      source_id: 'abb-1',
+      title: 'Drive',
+      author: 'James S. A. Corey',
+      series_name: 'The Expanse',
+      series_position: 2.6,
+      language: 'en',
+      content_type: 'audiobook',
+    });
+    expect(payload.multi_book).toBeUndefined();
+    expect(payload.book_plan).toBeUndefined();
+  });
+
+  it('uses the release title and author for manual books', () => {
+    const manual: Book = { ...book, provider: 'manual', title: 'ignored' };
+    const withAuthor = { ...release, extra: { author: 'Release Author' } };
+    const payload = buildReleaseDownloadPayload(manual, withAuthor, 'audiobook');
+    expect(payload.title).toBe(release.title);
+    expect(payload.author).toBe('Release Author');
+  });
+
+  it('flags a manual multi-book pack', () => {
+    const payload = buildReleaseDownloadPayload(book, release, 'audiobook', { multiBook: true });
+    expect(payload.multi_book).toBe(true);
+    expect(payload.book_plan).toBeUndefined();
+  });
+
+  it('attaches the approved book plan', () => {
+    const plan = [{ title: 'Leviathan Wakes', series_position: 1, year: 2011, files: ['a.m4b'] }];
+    const payload = buildReleaseDownloadPayload(book, release, 'audiobook', {
+      multiBook: true,
+      bookPlan: plan,
+    });
+    expect(payload.multi_book).toBe(true);
+    expect(payload.book_plan).toEqual(plan);
+  });
+});

src/frontend/src/types/index.ts

@@ -460,6 +460,27 @@ export interface SourceSearchInfo {
 }
 
 // Response from /api/releases endpoint
+/** One book split out of a multi-book pack release, files as release-relative paths. */
+export interface PackBook {
+  title: string;
+  series_position: number | null;
+  year: number | null;
+  files: string[];
+}
+
+export interface PackPlan {
+  is_pack: boolean;
+  books: PackBook[];
+  ignored: string[];
+}
+
+export interface InspectReleaseResponse {
+  inspected: boolean;
+  reason: string | null;
+  files: { path: string; size: number | null }[];
+  plan: PackPlan | null;
+}
+
 export interface ReleasesResponse {
   releases: Release[];
   book: {

src/frontend/src/utils/packReview.ts

@@ -0,0 +1,39 @@
+import type { PackBook } from '../types';
+
+/** Return a copy of `books` with one entry patched; the input is not mutated. */
+export function updateReviewBook(
+  books: PackBook[],
+  index: number,
+  patch: Partial<PackBook>,
+): PackBook[] {
+  return books.map((book, i) => (i === index ? { ...book, ...patch } : book));
+}
+
+/** Parse a series-position text field: "3" → 3, "2.5" → 2.5, blank/junk → null. */
+export function parseSeriesPositionInput(value: string): number | null {
+  const trimmed = value.trim();
+  if (!trimmed) return null;
+  const parsed = Number(trimmed);
+  return Number.isFinite(parsed) ? parsed : null;
+}
+
+/** The plan sent with the download: trimmed titles, untitled books dropped. */
+export function toBookPlanPayload(books: PackBook[]): PackBook[] {
+  return books
+    .map((book) => ({ ...book, title: book.title.trim() }))
+    .filter((book) => book.title.length > 0 && book.files.length > 0);
+}
+
+function plural(count: number, noun: string): string {
+  return `${count} ${noun}${count === 1 ? '' : 's'}`;
+}
+
+/** "2 books · 3 files · 2 files ignored" */
+export function describePackPlan(books: PackBook[], ignored: string[]): string {
+  const fileCount = books.reduce((sum, book) => sum + book.files.length, 0);
+  const parts = [plural(books.length, 'book'), plural(fileCount, 'file')];
+  if (ignored.length > 0) {
+    parts.push(`${plural(ignored.length, 'file')} ignored`);
+  }
+  return parts.join(' · ');
+}

src/frontend/src/utils/releasePayload.ts

@@ -0,0 +1,55 @@
+import type { DownloadReleasePayload } from '../services/api';
+import type { Book, ContentType, PackBook, Release } from '../types';
+
+export interface ReleaseDownloadOptions {
+  /** Ask post-processing to split the release into one book per subfolder/file. */
+  multiBook?: boolean;
+  /** The split the user approved in the pack review panel. */
+  bookPlan?: PackBook[];
+}
+
+/** Build the body for /api/releases/download (and /api/releases/inspect). */
+export function buildReleaseDownloadPayload(
+  book: Book,
+  release: Release,
+  releaseContentType: ContentType,
+  options: ReleaseDownloadOptions = {},
+): DownloadReleasePayload {
+  const isManual = book.provider === 'manual';
+  const releasePreview =
+    typeof release.extra?.preview === 'string' ? release.extra.preview : undefined;
+  const releaseAuthor =
+    typeof release.extra?.author === 'string' ? release.extra.author : undefined;
+
+  const payload: DownloadReleasePayload = {
+    source: release.source,
+    source_id: release.source_id,
+    title: isManual ? release.title : book.title,
+    author: isManual ? releaseAuthor || '' : book.author,
+    year: book.year,
+    format: release.format,
+    size: release.size,
+    size_bytes: release.size_bytes,
+    download_url: release.download_url,
+    protocol: release.protocol,
+    indexer: release.indexer,
+    seeders: release.seeders,
+    extra: release.extra,
+    preview: isManual ? releasePreview || undefined : book.preview,
+    content_type: releaseContentType,
+    series_name: book.series_name,
+    series_position: book.series_position,
+    subtitle: book.subtitle,
+    // From the release, never the book: book.language is the provider's
+    // canonical edition, which would mislabel a translated release.
+    language: release.language ?? undefined,
+  };
+
+  if (options.multiBook || options.bookPlan) {
+    payload.multi_book = true;
+  }
+  if (options.bookPlan) {
+    payload.book_plan = options.bookPlan;
+  }
+  return payload;
+}

tests/audiobookbay/conftest.py

@@ -0,0 +1,13 @@
+"""AudiobookBay test fixtures."""
+
+import pytest
+
+from shelfmark.release_sources.audiobookbay import scraper
+
+
+@pytest.fixture(autouse=True)
+def _clear_detail_page_cache():
+    """Detail pages are cached briefly in production; tests must not share them."""
+    scraper.clear_detail_page_cache()
+    yield
+    scraper.clear_detail_page_cache()

tests/audiobookbay/test_file_list.py

@@ -0,0 +1,102 @@
+"""Tests for reading the torrent file list off an AudiobookBay detail page."""
+
+from shelfmark.download.postprocess.packs import PackFile
+from shelfmark.release_sources.audiobookbay import scraper
+
+# Trimmed from a real detail page (2026-08): the file rows sit between the
+# "Multifile Torrent" marker and the "Combined File Size" row.
+MULTIFILE_DETAIL_HTML = """
+<table>
+<tr><td>Tracker:</td><td>udp://tracker.torrent.eu.org:451/announce</td></tr>
+<tr><td>Creation Date:</td><td>Sun, 29 Mar 2026 21:09:39 +0200</td></tr>
+<tr><td colspan='2'>This is a Multifile Torrent</td></tr>
+<tr><td colspan='2'>The Expanse 9.0 - Leviathan Falls (2021).m4b 1.05 GBs</td></tr>
+<tr><td colspan='2'>The Expanse 0.1 - An Expanse Novella - Drive (2012).txt 340 Bytes</td></tr>
+<tr><td colspan='2'>The Expanse 0.2 - An Expanse Novella - The Churn (2014).m4b 125.72 MBs</td></tr>
+<tr><td colspan='2'>The Expanse 2.0 - Caliban’s War (2012).m4b 578.97 MBs</td></tr>
+<tr><td>Combined File Size:</td><td><span style='color:#00f;'>7.87</span> GBs</td></tr>
+<tr><td>Info Hash:</td><td>e4a5538e26987ee58a43aa629ec2c4f2b2d46526</td></tr>
+</table>
+"""
+
+SINGLE_FILE_DETAIL_HTML = """
+<table>
+<tr><td>Creation Date:</td><td>Sun, 29 Mar 2026 21:09:39 +0200</td></tr>
+<tr><td colspan='2'>Drive.m4b 41.55 MBs</td></tr>
+<tr><td>Combined File Size:</td><td><span style='color:#00f;'>41.55</span> MBs</td></tr>
+<tr><td>Info Hash:</td><td>e4a5538e26987ee58a43aa629ec2c4f2b2d46526</td></tr>
+</table>
+"""
+
+
+def test_extracts_multifile_rows_with_byte_sizes():
+    files = scraper.extract_file_list(MULTIFILE_DETAIL_HTML)
+    assert files == [
+        PackFile("The Expanse 9.0 - Leviathan Falls (2021).m4b", int(1.05 * 1024**3)),
+        PackFile("The Expanse 0.1 - An Expanse Novella - Drive (2012).txt", 340),
+        PackFile(
+            "The Expanse 0.2 - An Expanse Novella - The Churn (2014).m4b", int(125.72 * 1024**2)
+        ),
+        PackFile("The Expanse 2.0 - Caliban’s War (2012).m4b", int(578.97 * 1024**2)),
+    ]
+
+
+def test_single_file_torrent_lists_the_row_before_combined_size():
+    assert scraper.extract_file_list(SINGLE_FILE_DETAIL_HTML) == [
+        PackFile("Drive.m4b", int(41.55 * 1024**2))
+    ]
+
+
+def test_page_without_file_table_returns_none():
+    assert scraper.extract_file_list("<html><body><p>nothing here</p></body></html>") is None
+
+
+class TestHandlerListFiles:
+    def test_lists_files_from_detail_page(self):
+        from unittest.mock import patch
+
+        from shelfmark.release_sources.audiobookbay.handler import AudiobookBayHandler
+
+        with patch(
+            "shelfmark.release_sources.audiobookbay.handler.scraper.fetch_detail_html",
+            return_value=SINGLE_FILE_DETAIL_HTML,
+        ) as fetch:
+            files = AudiobookBayHandler().list_files(
+                {"source_id": "abc", "download_url": "https://audiobookbay.lu/abss/drive/"}
+            )
+        assert files == [PackFile("Drive.m4b", int(41.55 * 1024**2))]
+        fetch.assert_called_once_with("https://audiobookbay.lu/abss/drive/", "audiobookbay.lu")
+
+    def test_rejects_detail_url_on_other_host(self):
+        from unittest.mock import patch
+
+        from shelfmark.release_sources.audiobookbay.handler import AudiobookBayHandler
+
+        with patch(
+            "shelfmark.release_sources.audiobookbay.handler.scraper.fetch_detail_html"
+        ) as fetch:
+            files = AudiobookBayHandler().list_files(
+                {"source_id": "abc", "download_url": "https://evil.example/abss/drive/"}
+            )
+        assert files is None
+        fetch.assert_not_called()
+
+
+def test_extract_magnet_link_and_file_list_share_one_page_fetch():
+    from unittest.mock import patch
+
+    page = MULTIFILE_DETAIL_HTML
+    with (
+        patch(
+            "shelfmark.release_sources.audiobookbay.scraper.downloader.html_get_page",
+            return_value=page,
+        ) as get_page,
+        patch("shelfmark.release_sources.audiobookbay.scraper._bootstrap_abb_session"),
+    ):
+        scraper.clear_detail_page_cache()
+        url = "https://audiobookbay.lu/abss/expanse/"
+        assert scraper.fetch_detail_html(url, "audiobookbay.lu") == page
+        magnet = scraper.extract_magnet_link(url, "audiobookbay.lu")
+    assert magnet is not None
+    assert "e4a5538e26987ee58a43aa629ec2c4f2b2d46526".upper() in magnet
+    assert get_page.call_count == 1

tests/core/test_processing_packs.py

@@ -0,0 +1,212 @@
+"""Multi-book packs are filed one book at a time through the normal pipeline."""
+
+import os
+from pathlib import Path
+from threading import Event
+from unittest.mock import patch
+
+from shelfmark.core.models import DownloadTask, SearchMode
+from tests.core.test_processing_integration import _build_config, _sync_config
+
+
+def _run(temp_path: Path, task: DownloadTask, ingest: Path, staging: Path, **config_kwargs):
+    from shelfmark.download.postprocess.router import post_process_download
+
+    statuses: list[tuple[str, str | None]] = []
+    with (
+        patch("shelfmark.core.config.config") as mock_config,
+        patch("shelfmark.config.env.TMP_DIR", staging),
+    ):
+        mock_config.get = _build_config(
+            ingest,
+            organization=config_kwargs.pop("organization", "organize"),
+            supported_audiobook_formats=["m4b", "mp3"],
+            audiobook_organize_template=config_kwargs.pop(
+                "audiobook_organize_template", "{Author}/{Title}/{Title}{ - PartNumber}"
+            ),
+            **config_kwargs,
+        )
+        mock_config.CUSTOM_SCRIPT = None
+        _sync_config(mock_config, mock_config)
+        result = post_process_download(
+            temp_path, task, Event(), lambda s, m=None: statuses.append((s, m))
+        )
+    return result, statuses
+
+
+def _nested_pack(root: Path) -> Path:
+    pack = root / "Sun Eater"
+    for folder, name in (
+        ("Book 1 - Empire of Silence", "empire.m4b"),
+        ("Book 2 - Howling Dark", "howling.m4b"),
+    ):
+        (pack / folder).mkdir(parents=True)
+        (pack / folder / name).write_text(name)
+    (pack / "cover.jpg").write_text("img")
+    return pack
+
+
+def _audiobook_task(**overrides) -> DownloadTask:
+    fields = {
+        "task_id": "pack-1",
+        "source": "direct_download",
+        "title": "Drive",
+        "author": "James S. A. Corey",
+        "content_type": "audiobook",
+        "series_name": "The Expanse",
+        "series_position": 2.6,
+        "search_mode": SearchMode.UNIVERSAL,
+    }
+    fields.update(overrides)
+    return DownloadTask(**fields)
+
+
+def test_approved_plan_files_each_book_with_its_own_title(tmp_path):
+    staging = tmp_path / "staging"
+    ingest = tmp_path / "ingest"
+    staging.mkdir()
+    ingest.mkdir()
+    pack = staging / "Expanse"
+    pack.mkdir()
+    for name in (
+        "The Expanse 1.0 - Leviathan Wakes (2011).m4b",
+        "The Expanse 2.0 - Caliban's War (2012).m4b",
+    ):
+        (pack / name).write_text(name)
+    (pack / "The Expanse 1.0 - Leviathan Wakes (2011).txt").write_text("notes")
+
+    task = _audiobook_task(
+        title="Sun Eater",  # the searched book; must not name the pack's books
+        book_plan=[
+            {
+                "title": "Leviathan Wakes (edited)",
+                "series_position": 1.0,
+                "year": 2011,
+                "files": ["The Expanse 1.0 - Leviathan Wakes (2011).m4b"],
+            },
+            {
+                "title": "Caliban's War",
+                "series_position": 2.0,
+                "year": 2012,
+                "files": ["The Expanse 2.0 - Caliban's War (2012).m4b"],
+            },
+        ],
+    )
+
+    result, statuses = _run(pack, task, ingest, staging)
+
+    assert result is not None
+    author_dir = ingest / "James S. A. Corey"
+    assert sorted(p.name for p in author_dir.iterdir()) == [
+        "Caliban's War",
+        "Leviathan Wakes (edited)",
+    ]
+    assert (author_dir / "Leviathan Wakes (edited)" / "Leviathan Wakes (edited).m4b").exists()
+    assert (author_dir / "Caliban's War" / "Caliban's War.m4b").exists()
+    assert statuses[-1] == ("complete", "Complete (2 books, 2 files)")
+
+
+def test_multi_book_flag_splits_nested_pack_heuristically(tmp_path):
+    staging = tmp_path / "staging"
+    ingest = tmp_path / "ingest"
+    staging.mkdir()
+    ingest.mkdir()
+    pack = _nested_pack(staging)
+
+    result, _ = _run(pack, _audiobook_task(multi_book=True), ingest, staging)
+
+    assert result is not None
+    author_dir = ingest / "James S. A. Corey"
+    assert (author_dir / "Empire of Silence" / "Empire of Silence.m4b").exists()
+    assert (author_dir / "Howling Dark" / "Howling Dark.m4b").exists()
+
+
+def test_pack_book_series_position_does_not_leak_from_searched_book(tmp_path):
+    staging = tmp_path / "staging"
+    ingest = tmp_path / "ingest"
+    staging.mkdir()
+    ingest.mkdir()
+    pack = staging / "Two"
+    for folder in ("Alpha", "Beta"):
+        (pack / folder).mkdir(parents=True)
+        (pack / folder / f"{folder.lower()}.m4b").write_text(folder)
+
+    result, _ = _run(
+        pack,
+        _audiobook_task(multi_book=True),
+        ingest,
+        staging,
+        audiobook_organize_template="{Author}/{SeriesPosition - }{Title}/{Title}",
+    )
+
+    assert result is not None
+    assert sorted(p.name for p in (ingest / "James S. A. Corey").iterdir()) == ["Alpha", "Beta"]
+
+
+def test_multifile_book_inside_pack_keeps_part_numbers_per_book(tmp_path):
+    staging = tmp_path / "staging"
+    ingest = tmp_path / "ingest"
+    staging.mkdir()
+    ingest.mkdir()
+    pack = staging / "Pack"
+    (pack / "Book 1 - One").mkdir(parents=True)
+    (pack / "Book 2 - Two").mkdir(parents=True)
+    for i in (1, 2, 3):
+        (pack / "Book 1 - One" / f"part{i}.mp3").write_text(str(i))
+    (pack / "Book 2 - Two" / "two.mp3").write_text("t")
+
+    result, statuses = _run(pack, _audiobook_task(multi_book=True), ingest, staging)
+
+    assert result is not None
+    one = ingest / "James S. A. Corey" / "One"
+    assert sorted(p.name for p in one.iterdir()) == ["One - 01.mp3", "One - 02.mp3", "One - 03.mp3"]
+    assert (ingest / "James S. A. Corey" / "Two" / "Two.mp3").exists()
+    assert statuses[-1] == ("complete", "Complete (2 books, 4 files)")
+
+
+def test_hardlinked_torrent_pack_leaves_source_tree_intact(tmp_path):
+    downloads = tmp_path / "downloads"
+    ingest = tmp_path / "ingest"
+    downloads.mkdir()
+    ingest.mkdir()
+    pack = _nested_pack(downloads)
+    task = _audiobook_task(source="prowlarr", multi_book=True, original_download_path=str(pack))
+
+    result, _ = _run(pack, task, ingest, tmp_path / "staging", hardlink=True)
+
+    assert result is not None
+    empire_src = pack / "Book 1 - Empire of Silence" / "empire.m4b"
+    empire_dst = ingest / "James S. A. Corey" / "Empire of Silence" / "Empire of Silence.m4b"
+    assert empire_src.exists()
+    assert empire_dst.exists()
+    assert os.stat(empire_src).st_ino == os.stat(empire_dst).st_ino
+
+
+def test_without_pack_fields_nested_pack_is_still_one_book(tmp_path):
+    staging = tmp_path / "staging"
+    ingest = tmp_path / "ingest"
+    staging.mkdir()
+    ingest.mkdir()
+    pack = _nested_pack(staging)
+
+    result, _ = _run(pack, _audiobook_task(), ingest, staging)
+
+    assert result is not None
+    drive = ingest / "James S. A. Corey" / "Drive"
+    assert sorted(p.name for p in drive.iterdir()) == ["Drive - 01.m4b", "Drive - 02.m4b"]
+
+
+def test_single_group_with_multi_book_flag_uses_searched_title(tmp_path):
+    staging = tmp_path / "staging"
+    ingest = tmp_path / "ingest"
+    staging.mkdir()
+    ingest.mkdir()
+    pack = staging / "Series" / "Book 1 - Solo"
+    pack.mkdir(parents=True)
+    (pack / "solo.m4b").write_text("s")
+
+    result, statuses = _run(pack.parent, _audiobook_task(multi_book=True), ingest, staging)
+
+    assert result is not None
+    assert (ingest / "James S. A. Corey" / "Drive" / "Drive.m4b").exists()
+    assert statuses[-1] == ("complete", "Complete")

tests/core/test_release_inspect_routes.py

@@ -0,0 +1,134 @@
+"""API tests for POST /api/releases/inspect."""
+
+from __future__ import annotations
+
+import importlib
+from unittest.mock import patch
+
+import pytest
+
+from shelfmark.download.postprocess.packs import PackFile
+
+
+@pytest.fixture(scope="module")
+def main_module():
+    with patch("shelfmark.download.orchestrator.start"):
+        import shelfmark.main as main
+
+        importlib.reload(main)
+        return main
+
+
+@pytest.fixture
+def client(main_module):
+    client = main_module.app.test_client()
+    with client.session_transaction() as sess:
+        sess["user_id"] = "tester"
+        sess["is_admin"] = False
+    return client
+
+
+class _Handler:
+    def __init__(self, files):
+        self._files = files
+
+    def list_files(self, release_data):
+        if isinstance(self._files, Exception):
+            raise self._files
+        return self._files
+
+
+def _inspect(client, handler, payload=None):
+    body = {
+        "source": "audiobookbay",
+        "source_id": "abc",
+        "title": "Drive",
+        "content_type": "audiobook",
+        "series_name": "The Expanse",
+        **(payload or {}),
+    }
+    with patch("shelfmark.core.release_inspect_routes.get_handler", return_value=handler):
+        return client.post("/api/releases/inspect", json=body)
+
+
+def test_pack_release_returns_a_plan(client):
+    files = [
+        PackFile("The Expanse 1.0 - Leviathan Wakes (2011).m4b", 100),
+        PackFile("The Expanse 1.0 - Leviathan Wakes (2011).txt", 1),
+        PackFile("The Expanse 2.0 - Caliban's War (2012).m4b", 100),
+    ]
+    resp = _inspect(client, _Handler(files))
+    assert resp.status_code == 200
+    data = resp.get_json()
+    assert data["inspected"] is True
+    assert data["reason"] is None
+    assert data["files"] == [
+        {"path": "The Expanse 1.0 - Leviathan Wakes (2011).m4b", "size": 100},
+        {"path": "The Expanse 1.0 - Leviathan Wakes (2011).txt", "size": 1},
+        {"path": "The Expanse 2.0 - Caliban's War (2012).m4b", "size": 100},
+    ]
+    assert data["plan"]["is_pack"] is True
+    assert data["plan"]["ignored"] == ["The Expanse 1.0 - Leviathan Wakes (2011).txt"]
+    assert data["plan"]["books"] == [
+        {
+            "title": "Leviathan Wakes",
+            "series_position": 1.0,
+            "year": 2011,
+            "files": ["The Expanse 1.0 - Leviathan Wakes (2011).m4b"],
+        },
+        {
+            "title": "Caliban's War",
+            "series_position": 2.0,
+            "year": 2012,
+            "files": ["The Expanse 2.0 - Caliban's War (2012).m4b"],
+        },
+    ]
+
+
+def test_single_book_release_is_not_a_pack(client):
+    resp = _inspect(client, _Handler([PackFile("Drive.m4b", 5)]))
+    data = resp.get_json()
+    assert data["inspected"] is True
+    assert data["plan"]["is_pack"] is False
+    assert len(data["plan"]["books"]) == 1
+
+
+def test_handler_without_file_list_reports_not_inspected(client):
+    resp = _inspect(client, _Handler(None))
+    assert resp.status_code == 200
+    data = resp.get_json()
+    assert data["inspected"] is False
+    assert data["reason"]
+    assert data["plan"] is None
+
+
+def test_handler_failure_reports_not_inspected_without_500(client):
+    resp = _inspect(client, _Handler(RuntimeError("boom")))
+    assert resp.status_code == 200
+    data = resp.get_json()
+    assert data["inspected"] is False
+    assert "boom" in data["reason"]
+
+
+def test_unknown_source_is_a_client_error(client):
+    with patch(
+        "shelfmark.core.release_inspect_routes.get_handler", side_effect=ValueError("no source")
+    ):
+        resp = client.post(
+            "/api/releases/inspect", json={"source": "nope", "source_id": "x", "title": "t"}
+        )
+    assert resp.status_code == 400
+
+
+def test_missing_source_id_is_a_client_error(client):
+    resp = client.post("/api/releases/inspect", json={"source": "audiobookbay"})
+    assert resp.status_code == 400
+
+
+def test_requires_login(main_module):
+    anonymous = main_module.app.test_client()
+    with patch.object(main_module, "load_active_auth_mode", return_value="builtin"):
+        resp = anonymous.post(
+            "/api/releases/inspect", json={"source": "audiobookbay", "source_id": "a"}
+        )
+    assert resp.status_code == 401

tests/download/test_orchestrator_pack_fields.py

@@ -0,0 +1,62 @@
+"""Pack fields (multi_book / book_plan) survive queueing and restart-safe retry."""
+
+from shelfmark.core.models import DownloadTask
+from shelfmark.download import orchestrator
+
+PLAN = [
+    {"title": "Leviathan Wakes", "series_position": 1.0, "year": 2011, "files": ["a.m4b"]},
+    {"title": "Caliban's War", "series_position": 2.0, "year": 2012, "files": ["b.m4b"]},
+]
+
+
+def test_task_defaults_to_single_book():
+    task = DownloadTask(task_id="t", source="prowlarr", title="T")
+    assert task.multi_book is False
+    assert task.book_plan is None
+
+
+def test_retry_payload_round_trips_pack_fields():
+    task = DownloadTask(task_id="t", source="prowlarr", title="T", multi_book=True, book_plan=PLAN)
+    payload = orchestrator.serialize_task_for_retry(task)
+    restored = orchestrator._restore_task_from_retry_payload(payload)
+    assert restored is not None
+    assert restored.multi_book is True
+    assert restored.book_plan == PLAN
+
+
+def test_retry_payload_drops_malformed_plan():
+    payload = orchestrator.serialize_task_for_retry(
+        DownloadTask(task_id="t", source="prowlarr", title="T")
+    )
+    payload["book_plan"] = "not a list"
+    restored = orchestrator._restore_task_from_retry_payload(payload)
+    assert restored is not None
+    assert restored.book_plan is None
+
+
+def test_queue_release_reads_pack_fields(monkeypatch):
+    captured: dict[str, DownloadTask] = {}
+
+    def fake_add(task: DownloadTask) -> bool:
+        captured["task"] = task
+        return True
+
+    monkeypatch.setattr(orchestrator.config, "get", lambda _key, default=None, **_kw: default)
+    monkeypatch.setattr(orchestrator, "_source_unavailable_message", lambda _source: None)
+    monkeypatch.setattr(orchestrator.book_queue, "add", fake_add)
+    monkeypatch.setattr(orchestrator, "ws_manager", None)
+
+    ok, error = orchestrator.queue_release(
+        {
+            "source": "direct_download",
+            "source_id": "abc",
+            "title": "The Expanse",
+            "content_type": "audiobook",
+            "multi_book": True,
+            "book_plan": PLAN,
+        },
+        0,
+    )
+    assert ok, error
+    assert captured["task"].multi_book is True
+    assert captured["task"].book_plan == PLAN

tests/download/test_packs.py

@@ -0,0 +1,282 @@
+"""Tests for multi-book pack planning (shelfmark.download.postprocess.packs)."""
+
+from pathlib import Path
+
+import pytest
+
+from shelfmark.download.postprocess.packs import (
+    PackBook,
+    PackFile,
+    group_files_into_books,
+    match_plan_to_files,
+    parse_pack_book_name,
+    plan_pack,
+)
+
+AUDIO = {"m4b", "mp3"}
+
+
+class TestParsePackBookName:
+    @pytest.mark.parametrize(
+        ("name", "expected"),
+        [
+            ("Book 3 - Howling Dark", ("Howling Dark", 3.0, None)),
+            ("Book 03: Howling Dark", ("Howling Dark", 3.0, None)),
+            ("03 - Empire of Silence", ("Empire of Silence", 3.0, None)),
+            ("2.5 - Interlude", ("Interlude", 2.5, None)),
+            ("[03] Empire of Silence", ("Empire of Silence", 3.0, None)),
+            ("#3 Empire of Silence", ("Empire of Silence", 3.0, None)),
+            ("3. Empire of Silence", ("Empire of Silence", 3.0, None)),
+            ("Empire of Silence", ("Empire of Silence", None, None)),
+            ("Empire of Silence (2018)", ("Empire of Silence", None, 2018)),
+        ],
+    )
+    def test_strips_series_markers(self, name, expected):
+        assert parse_pack_book_name(name, series_name=None) == expected
+
+    def test_strips_leading_series_name_and_trailing_year(self):
+        assert parse_pack_book_name(
+            "The Expanse 1.0 - Leviathan Wakes (2011)", series_name="The Expanse"
+        ) == ("Leviathan Wakes", 1.0, 2011)
+
+    def test_series_name_match_is_case_insensitive(self):
+        assert parse_pack_book_name(
+            "the expanse 2.5 - Gods of Risk", series_name="The Expanse"
+        ) == (
+            "Gods of Risk",
+            2.5,
+            None,
+        )
+
+    @pytest.mark.parametrize(
+        "name",
+        [
+            "The Expanse 0.2 - An Expanse Novella - The Churn (2014)",
+            "The Expanse 0.2 - The Expanse Novella - The Churn (2014)",
+            "The Expanse 0.2 - An Expanse Short Story - The Churn (2014)",
+        ],
+    )
+    def test_strips_series_novella_label(self, name):
+        assert parse_pack_book_name(name, series_name="The Expanse") == ("The Churn", 0.2, 2014)
+
+    @pytest.mark.parametrize(
+        ("name", "expected"),
+        [
+            ("Uncrowned Cradle, Book 7", ("Uncrowned", 7.0, None)),
+            ("Reaper Cradle, Volume 10", ("Reaper", 10.0, None)),
+            ("Soulsmith  Cradle, Book 2", ("Soulsmith", 2.0, None)),
+            ("Wintersteel - Cradle Book 8", ("Wintersteel", 8.0, None)),
+            ("Wintersteel (Cradle, Book 8)", ("Wintersteel", 8.0, None)),
+            # A trailing bare number is a chapter/part, never a series position.
+            ("Unsouled - 02", ("Unsouled - 02", None, None)),
+        ],
+    )
+    def test_trailing_series_marker(self, name, expected):
+        assert parse_pack_book_name(name, series_name="Cradle") == expected
+
+    def test_trailing_series_name_only_stripped_with_a_marker(self):
+        # "Stories from Cradle" is the title; nothing marks a position, so keep it.
+        assert parse_pack_book_name("Threshold: Stories from Cradle", series_name="Cradle") == (
+            "Threshold: Stories from Cradle",
+            None,
+            None,
+        )
+
+    @pytest.mark.parametrize(
+        ("name", "expected"),
+        [
+            # AudiobookBay renders "<folder> <file>" as one flat string.
+            (
+                "Will Wight - Unsouled Cradle, Book 1 Will Wight - Unsouled Cradle, Book 1",
+                ("Unsouled", 1.0, None),
+            ),
+            (
+                "Will Wight - Skysworn Cradle, Book 4 Skysworn Cradle, Book 4",
+                ("Skysworn", 4.0, None),
+            ),
+            ("Will Wight - Bloodline Cradle, Book 9", ("Bloodline", 9.0, None)),
+        ],
+    )
+    def test_strips_author_prefix_and_glued_folder_name(self, name, expected):
+        assert (
+            parse_pack_book_name(name, series_name="Cradle", author_name="Will Wight") == expected
+        )
+
+    @pytest.mark.parametrize(
+        ("name", "expected"),
+        [
+            ("Gods of Risk 2.5 - Gods of Risk", ("Gods of Risk", 2.5, None)),
+            ("Cibola Burn 4 - Cibola Burn (2014)", ("Cibola Burn", 4.0, 2014)),
+            ("cibola burn 4 - Cibola Burn", ("Cibola Burn", 4.0, None)),
+            # Different text on each side is a real "Series N - Title" name, not a repeat.
+            ("Sun Eater 2 - Howling Dark", ("Sun Eater 2 - Howling Dark", None, None)),
+        ],
+    )
+    def test_collapses_title_repeated_around_the_position(self, name, expected):
+        assert parse_pack_book_name(name, series_name=None) == expected
+
+    def test_bare_numeric_title_is_left_alone(self):
+        assert parse_pack_book_name("1984", series_name=None) == ("1984", None, None)
+
+    def test_marker_that_would_leave_nothing_is_left_alone(self):
+        assert parse_pack_book_name("Book 3", series_name=None) == ("Book 3", None, None)
+
+
+class TestPlanPack:
+    def test_nested_subfolders_become_separate_books(self):
+        files = [
+            PackFile("Sun Eater/Book 1 - Empire of Silence/Empire of Silence.m4b", 10),
+            PackFile("Sun Eater/Book 2 - Howling Dark/Howling Dark.m4b", 20),
+            PackFile("Sun Eater/cover.jpg", 1),
+        ]
+        plan = plan_pack(files, supported_extensions=AUDIO, series_name=None)
+        assert plan.is_pack
+        assert [b.title for b in plan.books] == ["Empire of Silence", "Howling Dark"]
+        assert [b.series_position for b in plan.books] == [1.0, 2.0]
+        assert plan.books[0].files == ["Sun Eater/Book 1 - Empire of Silence/Empire of Silence.m4b"]
+        assert plan.ignored == ["Sun Eater/cover.jpg"]
+
+    def test_flat_pack_becomes_one_book_per_file_and_ignores_sidecars(self):
+        files = [
+            PackFile("The Expanse 1.0 - Leviathan Wakes (2011).m4b", 100),
+            PackFile("The Expanse 1.0 - Leviathan Wakes (2011).txt", 1),
+            PackFile("The Expanse 2.0 - Caliban's War (2012).m4b", 100),
+        ]
+        plan = plan_pack(files, supported_extensions=AUDIO, series_name="The Expanse")
+        assert plan.is_pack
+        assert [(b.title, b.series_position, b.year) for b in plan.books] == [
+            ("Leviathan Wakes", 1.0, 2011),
+            ("Caliban's War", 2.0, 2012),
+        ]
+        assert plan.ignored == ["The Expanse 1.0 - Leviathan Wakes (2011).txt"]
+
+    def test_audiobookbay_flat_list_with_trailing_markers_is_a_pack(self):
+        # ABB's file table has no folder separators: "<folder> <file> <size>".
+        files = [
+            PackFile(
+                "Will Wight - Unsouled Cradle, Book 1 Will Wight - Unsouled Cradle, Book 1.sfv", 1
+            ),
+            PackFile(
+                "Will Wight - Unsouled Cradle, Book 1 Will Wight - Unsouled Cradle, Book 1.m4a", 9
+            ),
+            PackFile("Will Wight - Skysworn Cradle, Book 4 Skysworn Cradle, Book 4.m4b", 9),
+            PackFile("Uncrowned Cradle, Book 7.m4b", 9),
+            PackFile(
+                "Will Wight - Reaper Cradle, Volume 10 Will Wight - Reaper Cradle, Volume 10.m4b", 9
+            ),
+        ]
+        plan = plan_pack(
+            files,
+            supported_extensions={"m4a", "m4b"},
+            series_name="Cradle",
+            author_name="Will Wight",
+        )
+        assert plan.is_pack
+        assert [(b.title, b.series_position) for b in plan.books] == [
+            ("Unsouled", 1.0),
+            ("Skysworn", 4.0),
+            ("Uncrowned", 7.0),
+            ("Reaper", 10.0),
+        ]
+
+    def test_deeper_nesting_collapses_onto_book_folder(self):
+        files = [
+            PackFile("Book 1/CD1/01.mp3"),
+            PackFile("Book 1/CD2/01.mp3"),
+            PackFile("Book 2/01.mp3"),
+        ]
+        plan = plan_pack(files, supported_extensions=AUDIO, series_name=None)
+        assert [b.files for b in plan.books] == [
+            ["Book 1/CD1/01.mp3", "Book 1/CD2/01.mp3"],
+            ["Book 2/01.mp3"],
+        ]
+
+    def test_single_wrapping_folder_is_not_a_book_boundary(self):
+        # A torrent named "Series" containing one multi-part book is a single book.
+        files = [PackFile("Series/Book 1/01.mp3"), PackFile("Series/Book 1/02.mp3")]
+        plan = plan_pack(files, supported_extensions=AUDIO, series_name=None)
+        assert not plan.is_pack
+        assert len(plan.books) == 1
+
+    def test_root_files_and_subfolders_coexist(self):
+        files = [PackFile("Novella.m4b"), PackFile("Book 1/a.m4b"), PackFile("Book 1/b.m4b")]
+        plan = plan_pack(files, supported_extensions=AUDIO, series_name=None)
+        assert [b.files for b in plan.books] == [["Novella.m4b"], ["Book 1/a.m4b", "Book 1/b.m4b"]]
+
+    def test_single_file_is_not_a_pack(self):
+        plan = plan_pack([PackFile("Book.m4b")], supported_extensions=AUDIO, series_name=None)
+        assert not plan.is_pack
+        assert plan.books[0].title == "Book"
+
+    def test_empty_input(self):
+        plan = plan_pack([], supported_extensions=AUDIO, series_name=None)
+        assert plan.books == []
+        assert not plan.is_pack
+
+
+class TestGroupFilesIntoBooks:
+    def test_groups_on_disk_files_by_top_level_folder(self, tmp_path: Path):
+        a = tmp_path / "Book 1 - A" / "a.m4b"
+        b = tmp_path / "Book 2 - B" / "b.m4b"
+        for f in (a, b):
+            f.parent.mkdir(parents=True)
+            f.write_bytes(b"x")
+        groups = group_files_into_books([a, b], series_name=None)
+        assert [(g.title, g.series_position, g.files) for g in groups] == [
+            ("A", 1.0, [a]),
+            ("B", 2.0, [b]),
+        ]
+
+
+class TestMatchPlanToFiles:
+    def test_matches_by_relative_path_then_basename(self, tmp_path: Path):
+        root = tmp_path / "staging" / "Sun Eater"
+        a = root / "Book 1 - A" / "a.m4b"
+        b = root / "Book 2 - B" / "b.m4b"
+        for f in (a, b):
+            f.parent.mkdir(parents=True)
+            f.write_bytes(b"x")
+        plan = [
+            PackBook(title="Alpha", series_position=1.0, year=2001, files=["Book 1 - A/a.m4b"]),
+            PackBook(title="Beta", series_position=2.0, year=None, files=["b.m4b"]),
+        ]
+        groups = match_plan_to_files(plan, [a, b])
+        assert [(g.title, g.series_position, g.year, g.files) for g in groups] == [
+            ("Alpha", 1.0, 2001, [a]),
+            ("Beta", 2.0, None, [b]),
+        ]
+
+    def test_matches_glued_plan_path_by_basename_suffix(self, tmp_path: Path):
+        # The plan came from ABB's "<folder> <file>" strings; on disk the file sits in a folder.
+        root = tmp_path / "Cradle - Will Wight Books 1-10"
+        a = root / "Will Wight - Skysworn Cradle, Book 4" / "Skysworn Cradle, Book 4.m4b"
+        b = root / "Uncrowned Cradle, Book 7.m4b"
+        for f in (a, b):
+            f.parent.mkdir(parents=True, exist_ok=True)
+            f.write_bytes(b"x")
+        plan = [
+            PackBook(
+                title="Skysworn",
+                series_position=4.0,
+                year=None,
+                files=["Will Wight - Skysworn Cradle, Book 4 Skysworn Cradle, Book 4.m4b"],
+            ),
+            PackBook(
+                title="Uncrowned",
+                series_position=7.0,
+                year=None,
+                files=["Uncrowned Cradle, Book 7.m4b"],
+            ),
+        ]
+        groups = match_plan_to_files(plan, [a, b])
+        assert [(g.title, g.files) for g in groups] == [("Skysworn", [a]), ("Uncrowned", [b])]
+
+    def test_unmatched_files_fall_back_to_heuristic_groups(self, tmp_path: Path):
+        a = tmp_path / "Book 1 - A" / "a.m4b"
+        c = tmp_path / "Book 3 - C" / "c.m4b"
+        for f in (a, c):
+            f.parent.mkdir(parents=True)
+            f.write_bytes(b"x")
+        plan = [PackBook(title="Alpha", series_position=1.0, year=None, files=["Book 1 - A/a.m4b"])]
+        groups = match_plan_to_files(plan, [a, c])
+        assert [(g.title, g.files) for g in groups] == [("Alpha", [a]), ("C", [c])]

tests/prowlarr/test_torrent_file_list.py

@@ -0,0 +1,98 @@
+"""Tests for listing the files inside a .torrent without downloading it."""
+
+from shelfmark.download.clients.torrent_utils import (
+    bencode_encode,
+    extract_file_list_from_torrent,
+)
+from shelfmark.download.postprocess.packs import PackFile
+
+
+def _torrent(info: dict) -> bytes:
+    return bencode_encode({b"announce": b"http://t/announce", b"info": info})
+
+
+def test_multi_file_torrent_lists_release_relative_paths():
+    data = _torrent(
+        {
+            b"name": b"Sun Eater",
+            b"piece length": 16384,
+            b"pieces": b"x" * 20,
+            b"files": [
+                {b"length": 10, b"path": [b"Book 1 - Empire of Silence", b"empire.m4b"]},
+                {b"length": 20, b"path": [b"Book 2 - Howling Dark", b"howling.m4b"]},
+                {b"length": 1, b"path": [b"cover.jpg"]},
+            ],
+        }
+    )
+    assert extract_file_list_from_torrent(data) == [
+        PackFile("Sun Eater/Book 1 - Empire of Silence/empire.m4b", 10),
+        PackFile("Sun Eater/Book 2 - Howling Dark/howling.m4b", 20),
+        PackFile("Sun Eater/cover.jpg", 1),
+    ]
+
+
+def test_single_file_torrent_lists_its_one_file():
+    data = _torrent(
+        {b"name": b"Book.m4b", b"length": 42, b"piece length": 16384, b"pieces": b"x" * 20}
+    )
+    assert extract_file_list_from_torrent(data) == [PackFile("Book.m4b", 42)]
+
+
+def test_unparseable_data_returns_none():
+    assert extract_file_list_from_torrent(b"not a torrent") is None
+
+
+class TestProwlarrHandlerListFiles:
+    def _handler(self):
+        from shelfmark.release_sources.prowlarr.handler import ProwlarrHandler
+
+        return ProwlarrHandler()
+
+    def test_lists_files_from_torrent_url(self):
+        from unittest.mock import patch
+
+        from shelfmark.download.clients.torrent_utils import TorrentInfo
+
+        data = _torrent(
+            {b"name": b"Book.m4b", b"length": 42, b"piece length": 16384, b"pieces": b"x" * 20}
+        )
+        release = {
+            "protocol": "torrent",
+            "downloadUrl": "http://prowlarr/dl.torrent",
+            "magnetUrl": "magnet:?xt=urn:btih:abc",
+            "infoHash": "abc",
+        }
+        with (
+            patch("shelfmark.release_sources.prowlarr.handler.get_release", return_value=release),
+            patch(
+                "shelfmark.release_sources.prowlarr.handler.extract_torrent_info",
+                return_value=TorrentInfo(info_hash="abc", torrent_data=data, is_magnet=False),
+            ) as extract,
+        ):
+            files = self._handler().list_files({"source_id": "rel-1"})
+        assert files == [PackFile("Book.m4b", 42)]
+        extract.assert_called_once_with("http://prowlarr/dl.torrent", expected_hash="abc")
+
+    def test_magnet_only_release_cannot_be_listed(self):
+        from unittest.mock import patch
+
+        release = {"protocol": "torrent", "magnetUrl": "magnet:?xt=urn:btih:abc"}
+        with (
+            patch("shelfmark.release_sources.prowlarr.handler.get_release", return_value=release),
+            patch("shelfmark.release_sources.prowlarr.handler.extract_torrent_info") as extract,
+        ):
+            assert self._handler().list_files({"source_id": "rel-1"}) is None
+        extract.assert_not_called()
+
+    def test_usenet_release_cannot_be_listed(self):
+        from unittest.mock import patch
+
+        release = {"protocol": "usenet", "downloadUrl": "http://prowlarr/dl.nzb"}
+        with patch("shelfmark.release_sources.prowlarr.handler.get_release", return_value=release):
+            assert self._handler().list_files({"source_id": "rel-1"}) is None
+
+    def test_unknown_release_cannot_be_listed(self):
+        from unittest.mock import patch
+
+        with patch("shelfmark.release_sources.prowlarr.handler.get_release", return_value=None):
+            assert self._handler().list_files({"source_id": "missing"}) is None