Fix remote-priority merge postprocessing.

app/main.py

@@ -1,6 +1,7 @@
 import os
 from typing import Tuple
 from app.utils.config import server_config
+from app.utils.playlist_merge import SyncMode, sync_all_playlists, TEST_PLAYLIST_DIR
 from fastapi import FastAPI, Request, Form
 from fastapi.responses import HTMLResponse, RedirectResponse
 from fastapi.templating import Jinja2Templates
@@ -23,6 +24,30 @@ app.mount(
 )
 
 
+SYNC_MODE_OPTIONS = [
+    {
+        "value": SyncMode.LOCAL_FORCE.value,
+        "label": "完全本地优先（local_force）",
+        "description": "单向同步，本地覆盖云端且顺序以本地为准。",
+    },
+    {
+        "value": SyncMode.REMOTE_FORCE.value,
+        "label": "完全云端优先（remote_force）",
+        "description": "单向同步，云端覆盖本地且顺序以云端为准。",
+    },
+    {
+        "value": SyncMode.MERGE_LOCAL_PRIMARY.value,
+        "label": "双向合并（本地优先）",
+        "description": "三方合并，冲突时选择本地版本。",
+    },
+    {
+        "value": SyncMode.MERGE_REMOTE_PRIMARY.value,
+        "label": "双向合并（云端优先）",
+        "description": "三方合并，冲突时选择云端版本。",
+    },
+]
+
+
 def _get_cloud_playlists() -> Tuple[list[dict], str, dict]:
     """Fetch playlists and connection state from the remote Plex server."""
 
@@ -74,27 +99,96 @@ def _get_cloud_playlists() -> Tuple[list[dict], str, dict]:
     playlists.sort(key=lambda item: item["name"].lower())
     return playlists, status, server_info
 
-
-# 显示主页
-@app.get("/", response_class=HTMLResponse)
-async def home(request: Request, local_path: str = "playlist"):
+def _build_home_context(
+    request: Request,
+    local_path: str,
+    message: str | None = None,
+    message_type: str | None = None,
+    sync_result: dict | None = None,
+    selected_mode: str | None = None,
+):
     server_config.load()
     local_playlists = scan_local_playlists(local_path)
     cloud_playlists, connection_status, server_info = _get_cloud_playlists()
 
-    return templates.TemplateResponse(
-        "home.html",
-        {
-            "request": request,
-            "theme": server_config.theme,
-            "path": "/",
-            "local_playlists": local_playlists,
-            "local_path": local_path,
-            "cloud_playlists": cloud_playlists,
-            "connection_status": connection_status,
-            "server_info": server_info,
-        },
-    )
+    return {
+        "request": request,
+        "theme": server_config.theme,
+        "path": "/",
+        "local_playlists": local_playlists,
+        "local_path": local_path,
+        "cloud_playlists": cloud_playlists,
+        "connection_status": connection_status,
+        "server_info": server_info,
+        "sync_modes": SYNC_MODE_OPTIONS,
+        "selected_mode": selected_mode,
+        "message": message,
+        "message_type": message_type,
+        "sync_result": sync_result,
+    }
+
+
+# 显示主页
+@app.get("/", response_class=HTMLResponse)
+async def home(request: Request, local_path: str = "playlist"):
+    context = _build_home_context(request, local_path)
+
+    return templates.TemplateResponse("home.html", context)
+
+
+@app.post("/sync", response_class=HTMLResponse)
+async def trigger_sync(request: Request, mode: str = Form(...), local_path: str = Form("playlist")):
+    try:
+        sync_mode = SyncMode(mode)
+    except ValueError:
+        context = _build_home_context(
+            request,
+            local_path,
+            message=f"未知的同步策略：{mode}",
+            message_type="danger",
+            selected_mode=mode,
+        )
+        return templates.TemplateResponse("home.html", context)
+
+    try:
+        results = sync_all_playlists(
+            local_dir=local_path,
+            mode=sync_mode,
+            test_folder=TEST_PLAYLIST_DIR,
+        )
+        merged_count = sum(len(item.merged_paths) for item in results)
+        conflict_count = sum(len(item.conflicts) for item in results)
+        deleted_count = sum(1 for item in results if item.action == "deleted")
+        context = _build_home_context(
+            request,
+            local_path,
+            message="同步完成，输出已写入测试目录用于验证。",
+            message_type="success",
+            sync_result={
+                "mode": sync_mode.value,
+                "mode_label": next(
+                    (item["label"] for item in SYNC_MODE_OPTIONS if item["value"] == sync_mode.value),
+                    sync_mode.value,
+                ),
+                "merged_count": merged_count,
+                "conflict_count": conflict_count,
+                "delete_count": deleted_count,
+                "playlist_count": len(results),
+                "output_dir": TEST_PLAYLIST_DIR,
+            },
+            selected_mode=sync_mode.value,
+        )
+        return templates.TemplateResponse("home.html", context)
+    except Exception as exc:
+        logger.warning(f"Sync failed: {exc}")
+        context = _build_home_context(
+            request,
+            local_path,
+            message=f"同步失败：{exc}",
+            message_type="danger",
+            selected_mode=sync_mode.value,
+        )
+        return templates.TemplateResponse("home.html", context)
 
 
 # 登录页面和处理

app/templates/home.html

@@ -8,6 +8,60 @@
     </div>
 </div>
 
+{% if message %}
+<div class="alert alert-{{ message_type or 'info' }}" role="alert">
+    {{ message }}
+</div>
+{% endif %}
+
+<div class="card mb-4">
+    <div class="card-body">
+        <div class="d-flex flex-column flex-xl-row align-items-xl-center gap-3 mb-3">
+            <div>
+                <h5 class="card-title mb-0">选择同步策略</h5>
+                <small class="text-body-secondary">根据需要选择单向覆盖或双向合并策略</small>
+            </div>
+            <form class="ms-xl-auto w-100 w-xl-auto" method="post" action="/sync">
+                <div class="row gy-2 gx-2 align-items-end">
+                    <div class="col-12 col-lg-8">
+                        <label class="form-label mb-1">同步模式</label>
+                        <select class="form-select" name="mode">
+                            {% for option in sync_modes %}
+                            <option value="{{ option.value }}" {% if selected_mode == option.value %}selected{% endif %}>
+                                {{ option.label }}
+                            </option>
+                            {% endfor %}
+                        </select>
+                    </div>
+                    <div class="col-auto">
+                        <label class="form-label d-none d-lg-block">&nbsp;</label>
+                        <div>
+                            <button class="btn btn-primary" type="submit">
+                                <i class="bi bi-play-fill"></i>
+                                <span class="ms-1">开始同步</span>
+                            </button>
+                        </div>
+                    </div>
+                    <input type="hidden" name="local_path" value="{{ local_path }}">
+                </div>
+            </form>
+        </div>
+        <ul class="mb-0 text-body-secondary small ps-3">
+            <li><strong>完全本地优先</strong>：本地列表直接覆盖云端，顺序以本地为准（无 diff）。</li>
+            <li><strong>完全云端优先</strong>：云端列表直接覆盖本地，顺序以云端为准（无 diff）。</li>
+            <li><strong>双向合并（本地优先）</strong>：三方合并，冲突时选本地。</li>
+            <li><strong>双向合并（云端优先）</strong>：三方合并，冲突时选云端。</li>
+        </ul>
+        {% if sync_result %}
+        <div class="alert alert-info mt-3 mb-0" role="alert">
+            <div class="fw-semibold">{{ sync_result.mode_label }}</div>
+            <div class="small mb-1">播放列表：{{ sync_result.playlist_count }}，删除：{{ sync_result.delete_count }}，合并曲目：{{ sync_result.merged_count }}，冲突数：{{ sync_result.conflict_count }}</div>
+            <div class="small text-body-secondary">已写入：{{ sync_result.output_dir }}</div>
+        </div>
+        {% endif %}
+    </div>
+</div>
+
 <div class="row g-4">
     <div class="col-12 col-xl-6">
         <div class="card h-100">

app/utils/playlist_merge.py

@@ -0,0 +1,556 @@
+import os
+from collections import Counter
+from dataclasses import dataclass
+from enum import Enum
+from typing import Literal, Sequence
+
+from app.utils.config import server_config
+from app.utils.logger import logger
+from app.utils.plex_client import plex_client
+
+from merge3 import Merge3
+
+
+TEST_PLAYLIST_DIR = os.path.abspath(
+    os.path.join(os.path.dirname(__file__), "..", "test_playlists")
+)
+
+
+class ConflictResolutionStrategy(str, Enum):
+    LOCAL_PRIORITY = "local_priority"
+    REMOTE_PRIORITY = "remote_priority"
+    DELETE_PRIORITY = "delete_priority"
+    KEEP_PRIORITY = "keep_priority"
+
+
+class SyncMode(str, Enum):
+    LOCAL_FORCE = "local_force"
+    REMOTE_FORCE = "remote_force"
+    MERGE_LOCAL_PRIMARY = "merge_local_primary"
+    MERGE_REMOTE_PRIMARY = "merge_remote_primary"
+
+
+@dataclass
+class PlaylistSyncResult:
+    name: str
+    merged_paths: list[str]
+    conflicts: list[dict]
+    action: Literal["synced", "deleted"]
+    output_dir: str
+
+
+def load_paths(text: str) -> list[str]:
+    """Normalize playlist text into a list of absolute paths.
+
+    * Remove blank lines.
+    * Ignore comment or metadata lines starting with ``#``.
+    * Preserve order and allow duplicates.
+    """
+
+    output: list[str] = []
+    for line in text.splitlines():
+        line = line.strip()
+        if not line:
+            continue
+        if line.startswith("#"):
+            continue
+        output.append(line)
+    return output
+
+
+def playlist_to_text(paths: Sequence[str]) -> str:
+    """Convert list of paths into diff3-friendly text."""
+
+    return "\n".join(paths) + "\n"
+
+
+def save_paths(paths: Sequence[str]) -> str:
+    """Format playlist paths into m3u/m3u8 text."""
+
+    return "#EXTM3U\n" + "\n".join(paths) + "\n"
+
+
+@dataclass
+class MergeChunk:
+    type: Literal["normal", "conflict"]
+    text: str | None = None
+    base_text: str | None = None
+    local_text: str | None = None
+    remote_text: str | None = None
+    origin: str | None = None
+
+
+@dataclass
+class MergeResult:
+    merged_paths: list[str]
+    conflicts: list[dict]
+
+
+def _ensure_test_dir(folder: str = TEST_PLAYLIST_DIR) -> str:
+    os.makedirs(folder, exist_ok=True)
+    return folder
+
+
+def _read_text_if_exists(path: str) -> tuple[str, bool]:
+    try:
+        with open(path, "r", encoding="utf-8") as file:
+            return file.read(), True
+    except FileNotFoundError:
+        return "", False
+    except OSError:
+        return "", False
+
+
+def _save_playlist_to_folder(filename: str, paths: Sequence[str], folder: str) -> str:
+    _ensure_test_dir(folder)
+    file_path = os.path.join(folder, filename)
+    with open(file_path, "w", encoding="utf-8") as file:
+        file.write(save_paths(paths))
+    return file_path
+
+
+def _normalize_inputs(
+    base_text: str, local_text: str, remote_text: str, folder: str
+) -> tuple[list[str], list[str], list[str]]:
+    """Normalize playlist inputs and persist snapshots for inspection."""
+
+    base_paths = load_paths(base_text)
+    local_paths = load_paths(local_text)
+    remote_paths = load_paths(remote_text)
+
+    _save_playlist_to_folder("base_playlist.m3u8", base_paths, folder)
+    _save_playlist_to_folder("local_input.m3u8", local_paths, folder)
+    _save_playlist_to_folder("remote_input.m3u8", remote_paths, folder)
+
+    return base_paths, local_paths, remote_paths
+
+
+def _merge_chunks(
+    base_paths: Sequence[str], local_paths: Sequence[str], remote_paths: Sequence[str]
+) -> list[MergeChunk]:
+    merger = Merge3(base_paths, local_paths, remote_paths)
+    raw_chunks = list(merger.merge_groups())
+    chunks: list[MergeChunk] = []
+
+    for kind, *payload in raw_chunks:
+        if kind == "conflict":
+            base_lines, local_lines, remote_lines = payload  # type: ignore[misc]
+
+            # Absorb trailing side-only chunks that actually belong to this
+            # conflicting region (common in reorder scenarios).
+            while chunks and chunks[-1].origin in ("a", "b"):
+                previous = chunks.pop()
+                previous_lines = previous.text.splitlines() if previous.text else []
+
+                if previous.origin == "a":
+                    local_lines = previous_lines + local_lines
+                else:
+                    remote_lines = previous_lines + remote_lines
+
+            chunks.append(
+                MergeChunk(
+                    type="conflict",
+                    base_text=playlist_to_text(base_lines),
+                    local_text=playlist_to_text(local_lines),
+                    remote_text=playlist_to_text(remote_lines),
+                )
+            )
+        else:
+            lines = payload[0]
+            if not lines:
+                continue
+            chunk = MergeChunk(type="normal", text=playlist_to_text(lines), origin=kind)
+            chunks.append(chunk)
+
+    return chunks
+
+
+def _write_results(merged_lines: Sequence[str], folder: str) -> None:
+    _save_playlist_to_folder("local_result.m3u8", merged_lines, folder)
+    _save_playlist_to_folder("remote_result.m3u8", merged_lines, folder)
+    _save_playlist_to_folder("base_next.m3u8", merged_lines, folder)
+
+
+def _write_delete_marker(playlist: str, folder: str) -> str:
+    _ensure_test_dir(folder)
+    marker_path = os.path.join(folder, "delete.txt")
+    with open(marker_path, "w", encoding="utf-8") as file:
+        file.write(f"delete playlist {playlist}")
+    return marker_path
+
+
+def _resolve_conflict(conflict: dict, strategy: ConflictResolutionStrategy) -> list[str]:
+    local_lines = conflict["local"]
+    remote_lines = conflict["remote"]
+
+    if strategy == ConflictResolutionStrategy.LOCAL_PRIORITY:
+        return local_lines
+    if strategy == ConflictResolutionStrategy.REMOTE_PRIORITY:
+        return remote_lines
+    if strategy == ConflictResolutionStrategy.DELETE_PRIORITY:
+        if not local_lines or not remote_lines:
+            return []
+        return local_lines
+    if strategy == ConflictResolutionStrategy.KEEP_PRIORITY:
+        if local_lines:
+            return local_lines
+        if remote_lines:
+            return remote_lines
+        return []
+
+    raise ValueError(f"Unsupported conflict resolution strategy: {strategy}")
+
+
+def _postprocess_local_priority_merge(
+    merged_lines: list[str],
+    base_paths: Sequence[str],
+    local_paths: Sequence[str],
+    remote_paths: Sequence[str],
+) -> list[str]:
+    """Fix local-priority edge cases without disturbing existing order."""
+
+    base_counter = Counter(base_paths)
+    local_counter = Counter(local_paths)
+    remote_counter = Counter(remote_paths)
+    merged_counter = Counter(merged_lines)
+    merged = list(merged_lines)
+
+    # 1) Preserve tracks that only Remote added (not in Base or Local).
+    for track, remote_count in remote_counter.items():
+        if base_counter[track] == 0 and local_counter[track] == 0 and remote_count > 0:
+            current = merged_counter.get(track, 0)
+            while current < remote_count:
+                merged.append(track)
+                merged_counter[track] += 1
+                current += 1
+
+    # 2) For tracks only new in Local+Remote (not in Base), keep Local's count.
+    candidate_tracks = set(local_counter.keys()) | set(remote_counter.keys())
+    for track in candidate_tracks:
+        if base_counter[track] == 0 and local_counter[track] > 0 and remote_counter[track] > 0:
+            target = local_counter[track]
+            current = merged_counter.get(track, 0)
+
+            if current > target:
+                remove_needed = current - target
+                trimmed: list[str] = []
+                for path in reversed(merged):
+                    if remove_needed and path == track:
+                        remove_needed -= 1
+                        continue
+                    trimmed.append(path)
+                trimmed.reverse()
+                merged = trimmed
+                merged_counter = Counter(merged)
+                current = merged_counter.get(track, 0)
+
+            while current < target:
+                merged.append(track)
+                current += 1
+                merged_counter[track] = current
+
+    return merged
+
+def _postprocess_remote_priority_merge(
+    merged_lines: list[str],
+    base_paths: Sequence[str],
+    local_paths: Sequence[str],
+    remote_paths: Sequence[str],
+) -> list[str]:
+
+    base_counter = Counter(base_paths)
+    local_counter = Counter(local_paths)
+    remote_counter = Counter(remote_paths)
+
+    remote_base_tracks: list[str] = [
+        track for track in remote_paths if base_counter[track] > 0
+    ]
+
+    target_new_counter: dict[str, int] = {}
+    all_tracks = set(local_counter.keys()) | set(remote_counter.keys())
+    for track in all_tracks:
+        if base_counter[track] > 0:
+            continue
+        r_cnt = remote_counter.get(track, 0)
+        l_cnt = local_counter.get(track, 0)
+        if r_cnt > 0:
+            target_new_counter[track] = r_cnt
+        elif l_cnt > 0:
+            target_new_counter[track] = l_cnt
+
+    new_tracks: list[str] = []
+    used_counter: Counter[str] = Counter()
+
+    for track in remote_paths:
+        if base_counter[track] > 0:
+            continue
+        if track not in target_new_counter:
+            continue
+        if used_counter[track] >= target_new_counter[track]:
+            continue
+        new_tracks.append(track)
+        used_counter[track] += 1
+
+    for track in local_paths:
+        if base_counter[track] > 0:
+            continue 
+        if track not in target_new_counter:
+            continue
+        if used_counter[track] >= target_new_counter[track]:
+            continue
+        new_tracks.append(track)
+        used_counter[track] += 1
+
+    return remote_base_tracks + new_tracks
+
+
+def merge_playlists(
+    base_text: str,
+    local_text: str,
+    remote_text: str,
+    strategy: ConflictResolutionStrategy = ConflictResolutionStrategy.LOCAL_PRIORITY,
+    test_folder: str = TEST_PLAYLIST_DIR,
+) -> MergeResult:
+    """Merge playlists using diff3 and resolve conflicts per strategy.
+
+    The base, local, and remote normalized playlists are saved into ``test_folder``
+    for inspection. The merged playlist is also stored twice to simulate the
+    versions intended for local save and cloud upload.
+    """
+
+    base_paths, local_paths, remote_paths = _normalize_inputs(
+        base_text, local_text, remote_text, test_folder
+    )
+
+    chunks = _merge_chunks(base_paths, local_paths, remote_paths)
+    has_conflict = any(chunk.type == "conflict" for chunk in chunks)
+
+    merged_lines: list[str] = []
+    conflicts: list[dict] = []
+
+    for chunk in chunks:
+        if chunk.type == "normal":
+            merged_lines.extend(chunk.text.splitlines())
+        else:
+            conflict_info = {
+                "base": chunk.base_text.splitlines(),
+                "local": chunk.local_text.splitlines(),
+                "remote": chunk.remote_text.splitlines(),
+            }
+            conflicts.append(conflict_info)
+            resolved = _resolve_conflict(conflict_info, strategy)
+            merged_lines.extend(resolved)
+
+    if strategy == ConflictResolutionStrategy.LOCAL_PRIORITY:
+        merged_lines = _postprocess_local_priority_merge(
+            merged_lines, base_paths, local_paths, remote_paths
+        )
+
+    if strategy == ConflictResolutionStrategy.REMOTE_PRIORITY:
+        merged_lines = _postprocess_remote_priority_merge(
+            merged_lines, base_paths, local_paths, remote_paths
+        )
+
+    _write_results(merged_lines, test_folder)
+
+    return MergeResult(merged_paths=merged_lines, conflicts=conflicts)
+
+
+def _load_local_playlists(local_dir: str) -> dict[str, str]:
+    """Read all local playlists under ``local_dir`` keyed by stem name."""
+
+    playlists: dict[str, str] = {}
+    if not local_dir:
+        return playlists
+
+    absolute = os.path.abspath(local_dir)
+    if not os.path.isdir(absolute):
+        return playlists
+
+    for entry in os.scandir(absolute):
+        if entry.is_file() and entry.name.lower().endswith((".m3u", ".m3u8")):
+            stem, _ = os.path.splitext(entry.name)
+            try:
+                with open(entry.path, "r", encoding="utf-8") as file:
+                    playlists[stem] = file.read()
+            except OSError:
+                playlists[stem] = ""
+    return playlists
+
+
+def _load_playlist_snapshots(playlist: str, folder: str) -> tuple[str, str, str, bool, bool]:
+    """Load base/local/remote texts for a playlist from its test folder."""
+
+    playlist_folder = os.path.join(folder, playlist)
+    base_text, base_exists = _read_text_if_exists(
+        os.path.join(playlist_folder, "base_next.m3u8")
+    )
+    if not base_text:
+        alt_text, _ = _read_text_if_exists(
+            os.path.join(playlist_folder, "base_playlist.m3u8")
+        )
+        base_text = base_text or alt_text
+
+    remote_text, remote_exists = _read_text_if_exists(
+        os.path.join(playlist_folder, "remote_input.m3u8")
+    )
+
+    return base_text, remote_text, playlist_folder, remote_exists, base_exists
+
+
+def _fetch_remote_playlists() -> dict[str, str]:
+    """Retrieve remote playlists from Plex when connected.
+
+    Returns a mapping of playlist name to serialized playlist text. Failures to
+    connect or fetch playlists are logged and result in an empty mapping to
+    avoid blocking local testing.
+    """
+
+    server_config.load()
+    if not server_config.url:
+        return {}
+
+    try:
+        plex_client.connect(
+            token=server_config.token,
+            scheme=server_config.scheme,
+            url=server_config.url,
+            port=server_config.port,
+        )
+    except Exception as exc:  # pragma: no cover - network access
+        logger.warning(f"Failed to connect to Plex for remote playlists: {exc}")
+        return {}
+
+    playlists: dict[str, str] = {}
+    try:
+        for playlist in plex_client.server.playlists():
+            paths: list[str] = []
+            try:
+                for track in playlist.items():
+                    locations = getattr(track, "locations", None) or []
+                    if locations:
+                        paths.append(locations[0])
+            except Exception as exc:  # pragma: no cover - plex runtime
+                logger.warning(f"Failed to read playlist '{playlist.title}': {exc}")
+            playlists[playlist.title] = save_paths(paths)
+    except Exception as exc:  # pragma: no cover - plex runtime
+        logger.warning(f"Failed to enumerate remote playlists: {exc}")
+        return {}
+
+    return playlists
+
+
+def _sync_single_playlist(
+    playlist: str,
+    mode: SyncMode,
+    local_text: str | None,
+    base_text: str,
+    remote_text: str,
+    playlist_folder: str,
+    remote_present: bool,
+) -> PlaylistSyncResult:
+    local_present = local_text is not None
+    local_text = local_text or ""
+
+    if not base_text:
+        base_text = "#EXTM3U\n"
+    if not remote_text:
+        remote_text = "#EXTM3U\n"
+
+    if mode == SyncMode.LOCAL_FORCE:
+        if not local_present:
+            _write_delete_marker(playlist, playlist_folder)
+            return PlaylistSyncResult(playlist, [], [], "deleted", playlist_folder)
+
+        base_paths, local_paths, _ = _normalize_inputs(
+            base_text, local_text, remote_text, playlist_folder
+        )
+        merged_lines = list(local_paths)
+        _write_results(merged_lines, playlist_folder)
+        return PlaylistSyncResult(playlist, merged_lines, [], "synced", playlist_folder)
+
+    if mode == SyncMode.REMOTE_FORCE:
+        if not remote_present:
+            _write_delete_marker(playlist, playlist_folder)
+            return PlaylistSyncResult(playlist, [], [], "deleted", playlist_folder)
+
+        base_paths, _, remote_paths = _normalize_inputs(
+            base_text, local_text, remote_text, playlist_folder
+        )
+        merged_lines = list(remote_paths)
+        _write_results(merged_lines, playlist_folder)
+        return PlaylistSyncResult(playlist, merged_lines, [], "synced", playlist_folder)
+
+    if mode not in (SyncMode.MERGE_LOCAL_PRIMARY, SyncMode.MERGE_REMOTE_PRIMARY):
+        raise ValueError(f"Unsupported sync mode: {mode}")
+
+    merge_strategy = (
+        ConflictResolutionStrategy.LOCAL_PRIORITY
+        if mode == SyncMode.MERGE_LOCAL_PRIMARY
+        else ConflictResolutionStrategy.REMOTE_PRIORITY
+    )
+
+    merge_result = merge_playlists(
+        base_text=base_text,
+        local_text=local_text,
+        remote_text=remote_text,
+        strategy=merge_strategy,
+        test_folder=playlist_folder,
+    )
+
+    if not merge_result.merged_paths and (not local_present or not remote_present):
+        _write_delete_marker(playlist, playlist_folder)
+        return PlaylistSyncResult(
+            playlist, merge_result.merged_paths, merge_result.conflicts, "deleted", playlist_folder
+        )
+
+    return PlaylistSyncResult(
+        playlist, merge_result.merged_paths, merge_result.conflicts, "synced", playlist_folder
+    )
+
+
+def sync_all_playlists(
+    local_dir: str, mode: SyncMode, test_folder: str = TEST_PLAYLIST_DIR
+) -> list[PlaylistSyncResult]:
+    """Synchronize all playlists that can be matched by name."""
+
+    _ensure_test_dir(test_folder)
+    local_playlists = _load_local_playlists(local_dir)
+    remote_playlists = _fetch_remote_playlists()
+    playlist_names: set[str] = set(local_playlists.keys())
+
+    playlist_names.update(remote_playlists.keys())
+
+    for entry in os.scandir(test_folder):
+        if entry.is_dir():
+            playlist_names.add(entry.name)
+
+    results: list[PlaylistSyncResult] = []
+
+    for playlist in sorted(playlist_names):
+        base_text, snapshot_remote_text, playlist_folder, remote_exists, _ = _load_playlist_snapshots(
+            playlist, test_folder
+        )
+        local_text = local_playlists.get(playlist)
+
+        remote_text = remote_playlists.get(playlist)
+        remote_present = False
+        if remote_text:
+            remote_present = True
+        else:
+            remote_text = snapshot_remote_text
+            remote_present = bool(remote_text.strip()) or remote_exists
+
+        # Treat missing remote text as absent playlist.
+        result = _sync_single_playlist(
+            playlist=playlist,
+            mode=mode,
+            local_text=local_text,
+            base_text=base_text,
+            remote_text=remote_text,
+            playlist_folder=playlist_folder,
+            remote_present=remote_present,
+        )
+        results.append(result)
+
+    return results

requirements.txt

@@ -3,3 +3,4 @@ uvicorn[standard]
 jinja2
 python-multipart
 plexapi
+merge3