Live multi-machine sync: watch files, reconcile, alert on conflicts

Both machines now reflect each other's changes within a couple seconds, and
genuine Syncthing conflicts auto-merge with a backup and an alert.

- sync_watcher.py: QFileSystemWatcher (debounced, re-arms after atomic renames)
  emits a single `changed`; the manager decides if it was external.
- library_manager: `reload_from_disk()` re-reads and reconciles disk into memory
  (max play/skip counts, newest edit wins, playlist membership unioned), keeping
  local unsaved edits and object identity so open views stay valid, then refreshes
  the UI without touching the player. `flush()` records each file's (mtime, size)
  so our own writes are never mistaken for an external change. New signals
  library_reloaded / conflict_resolved.
- conflict_resolver: back up BOTH sides into .resolved/<ts>/{original,incoming}/
  before merging, return list[ConflictSummary], add restore_backup(); runs at
  startup and live.
- gui/conflict_dialog.py: modeless summary with Open/Restore backup; main_window
  shows it from a status-bar notice and preserves scroll+selection on reload.

Tests: tests/test_round16.py (9) + full suite green (225).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
2026-07-02 00:55:45 -04:00
parent 94e7c0713b
commit 9575f0400f
9 changed files with 691 additions and 99 deletions

View File

@ -1,56 +1,103 @@
import json
import re
import shutil
from dataclasses import dataclass, field
from datetime import datetime
from pathlib import Path
from lintunes.models import Track, Playlist
# Syncthing conflict file pattern: filename.sync-conflict-20240101-123456-ABCDEFG.json
CONFLICT_PATTERN = re.compile(r"^(.+)\.sync-conflict-(\d{8}-\d{6})-\w+(\.\w+)$")
def resolve_conflicts(data_dir: Path):
@dataclass
class ConflictSummary:
"""A human-readable record of one merged Syncthing conflict, surfaced to the
user and used to offer a restore from the backed-up pre-merge copies."""
file: str # display name, e.g. "library.json" or a playlist name
kind: str # "library" | "playlist" | "metadata" | "other"
lines: list[str] = field(default_factory=list) # what was reconciled
backup_dir: str = "" # <data_dir>/.resolved/<timestamp>
def resolve_conflicts(data_dir: Path) -> list[ConflictSummary]:
"""Merge any Syncthing ``*.sync-conflict-*`` files into their originals.
Before touching anything, both the current (original) file and the incoming
conflict file are copied into ``<data_dir>/.resolved/<timestamp>/`` so the
merge is always reversible. Returns one ConflictSummary per conflict (empty
list when there was nothing to do)."""
if not data_dir.exists():
return
return []
resolved_dir = data_dir / ".resolved"
conflict_files = _find_conflict_files(data_dir)
if not conflict_files:
return
return []
print(f"Found {len(conflict_files)} Syncthing conflict(s), resolving...")
resolved_dir.mkdir(exist_ok=True)
stamp = datetime.now().strftime("%Y%m%d-%H%M%S")
backup_dir = data_dir / ".resolved" / stamp
(backup_dir / "original").mkdir(parents=True, exist_ok=True)
(backup_dir / "incoming").mkdir(parents=True, exist_ok=True)
summaries = []
for conflict_path, original_path in conflict_files:
if not original_path.exists():
# Original was deleted; just archive the conflict
_archive(conflict_path, resolved_dir)
continue
rel = original_path.relative_to(data_dir)
# Back up both sides first (belt and suspenders).
if original_path.exists():
_copy(original_path, backup_dir / "original" / rel)
_copy(conflict_path, backup_dir / "incoming" / rel)
try:
if original_path.name == "library.json":
_merge_library(original_path, conflict_path)
if not original_path.exists():
summary = ConflictSummary(
str(rel), "other",
["Deleted here but edited elsewhere — kept the deletion; "
"the other copy is in the backup."])
elif original_path.name == "library.json":
summary = _merge_library(original_path, conflict_path)
elif original_path.name == "library_metadata.json":
_merge_metadata(original_path, conflict_path)
summary = _merge_metadata(original_path, conflict_path)
elif original_path.parent.name == "playlists":
_merge_playlist(original_path, conflict_path)
summary = _merge_playlist(original_path, conflict_path)
else:
# Unknown file type — keep the newer one
_keep_newer(original_path, conflict_path)
except Exception as e:
print(f" Warning: Failed to merge {conflict_path.name}: {e}")
summary = _keep_newer(original_path, conflict_path)
except Exception as e: # never let a bad file abort startup/live reload
summary = ConflictSummary(
str(rel), "other",
[f"Could not merge automatically ({e}); both versions are in the "
"backup, current copy left as-is."])
_archive(conflict_path, resolved_dir)
summary.backup_dir = str(backup_dir)
summaries.append(summary)
# Remove the conflict file from the data dir (its copy is in the backup)
# so it isn't reprocessed and Syncthing stops flagging it.
conflict_path.unlink(missing_ok=True)
print(f" Resolved {len(conflict_files)} conflict(s)")
return summaries
def restore_backup(backup_dir: Path, data_dir: Path) -> list[str]:
"""Undo a merge: copy the pre-merge ``original/`` snapshot back over the
current files. Returns the list of restored relative paths."""
original_root = Path(backup_dir) / "original"
restored = []
if not original_root.exists():
return restored
for src in original_root.rglob("*"):
if src.is_file():
rel = src.relative_to(original_root)
dest = Path(data_dir) / rel
dest.parent.mkdir(parents=True, exist_ok=True)
shutil.copy2(src, dest)
restored.append(str(rel))
return restored
def _find_conflict_files(data_dir: Path) -> list[tuple[Path, Path]]:
results = []
for path in data_dir.rglob("*.sync-conflict-*"):
if ".resolved" in path.parts: # don't reprocess our own backups
continue
match = CONFLICT_PATTERN.match(path.name)
if match:
original_name = match.group(1) + match.group(3)
@ -59,35 +106,57 @@ def _find_conflict_files(data_dir: Path) -> list[tuple[Path, Path]]:
return results
def _merge_library(original_path: Path, conflict_path: Path):
def _merge_library(original_path: Path, conflict_path: Path) -> ConflictSummary:
original = _load_json(original_path)
conflict = _load_json(conflict_path)
added = 0
changed = 0
examples: list[str] = []
for tid, conflict_track_data in conflict.items():
if tid not in original:
# New track from conflict side
original[tid] = conflict_track_data
added += 1
continue
orig_track = original[tid]
_merge_track_fields(orig_track, conflict_track_data)
notes = _merge_track_fields(original[tid], conflict_track_data)
if notes:
changed += 1
if len(examples) < 8:
name = original[tid].get("name") or f"track {tid}"
examples.append(f"{name}”: {notes[0]}")
_save_json(original_path, original)
lines = []
if changed:
lines.append(f"{changed} track(s) reconciled "
"(play counts kept highest, newest edits win).")
if added:
lines.append(f"{added} track(s) present only on the other machine were kept.")
if not lines:
lines.append("No differences needed reconciling.")
lines.extend(examples)
return ConflictSummary("library.json", "library", lines)
def _merge_track_fields(orig: dict, conflict: dict):
def _merge_track_fields(orig: dict, conflict: dict) -> list[str]:
"""Merge conflict's track fields into orig in place; return change notes."""
notes = []
# play_count, skip_count: take max
for field in ("play_count", "skip_count"):
if field in conflict:
orig[field] = max(orig.get(field, 0), conflict[field])
for field_name, label in (("play_count", "play count"), ("skip_count", "skip count")):
if field_name in conflict:
new = max(orig.get(field_name, 0), conflict[field_name])
if new != orig.get(field_name, 0):
notes.append(f"{label} {orig.get(field_name, 0)}{new}")
orig[field_name] = new
# play_date_utc: take most recent
for field in ("play_date_utc", "skip_date"):
if field in conflict:
orig_val = orig.get(field)
conf_val = conflict[field]
# play_date_utc, skip_date: take most recent
for field_name in ("play_date_utc", "skip_date"):
if field_name in conflict:
orig_val = orig.get(field_name)
conf_val = conflict[field_name]
if orig_val is None or (conf_val and conf_val > orig_val):
orig[field] = conf_val
orig[field_name] = conf_val
# date_added: take earliest
if "date_added" in conflict:
@ -96,70 +165,93 @@ def _merge_track_fields(orig: dict, conflict: dict):
if orig_val is None or (conf_val and conf_val < orig_val):
orig["date_added"] = conf_val
# loved: OR (true wins)
# loved: OR (true wins). Legacy field — unused by LinTunes but preserved so a
# merge never silently clears it.
if conflict.get("loved", False):
orig["loved"] = True
# rating, metadata: newest date_modified wins
# rating + editable metadata: newest date_modified wins
orig_mod = orig.get("date_modified")
conf_mod = conflict.get("date_modified")
if conf_mod and (not orig_mod or conf_mod > orig_mod):
# Conflict is newer — take its metadata fields
for field in ("rating", "name", "artist", "album_artist", "album",
"genre", "composer", "grouping", "comments",
"sort_name", "sort_artist", "sort_album_artist",
"sort_album", "sort_composer", "date_modified"):
if field in conflict:
orig[field] = conflict[field]
if conflict.get("rating") != orig.get("rating") and "rating" in conflict:
notes.append(f"rating {_stars(orig.get('rating'))}"
f"{_stars(conflict.get('rating'))} (newer)")
for field_name in ("rating", "name", "artist", "album_artist", "album",
"genre", "composer", "grouping", "comments",
"sort_name", "sort_artist", "sort_album_artist",
"sort_album", "sort_composer", "date_modified"):
if field_name in conflict:
orig[field_name] = conflict[field_name]
return notes
def _merge_playlist(original_path: Path, conflict_path: Path):
def _merge_playlist(original_path: Path, conflict_path: Path) -> ConflictSummary:
original = _load_json(original_path)
conflict = _load_json(conflict_path)
name = original.get("name") or conflict.get("name") or original_path.stem
# Smart playlists: membership is derived, so unioning track_ids would
# resurrect tracks that no longer match. Keep the newer file's criteria;
# membership is recomputed from it at the next launch.
# Smart playlists: membership is derived, so keep the newer criteria and let
# it recompute (unioning derived track_ids would resurrect non-matches).
if original.get("playlist_type") == "smart" or conflict.get("playlist_type") == "smart":
_keep_newer(original_path, conflict_path)
return
newer = _keep_newer(original_path, conflict_path)
newer.file, newer.kind = name, "playlist"
newer.lines = ["Smart-playlist rules taken from the most recently edited copy."]
return newer
# Union track_ids, order from the newer file
orig_ids = set(original.get("track_ids", []))
conf_ids = set(conflict.get("track_ids", []))
all_ids = orig_ids | conf_ids
orig_ids = list(original.get("track_ids", []))
conf_ids = list(conflict.get("track_ids", []))
orig_set, conf_set = set(orig_ids), set(conf_ids)
# Determine which file is newer by checking file mtime
if conflict_path.stat().st_mtime > original_path.stat().st_mtime:
# Use conflict's order as base, append any missing from original
base_order = conflict.get("track_ids", [])
extra = [tid for tid in original.get("track_ids", []) if tid not in conf_ids]
conflict_newer = conflict_path.stat().st_mtime > original_path.stat().st_mtime
if conflict_newer:
base_order = conf_ids
extra = [tid for tid in orig_ids if tid not in conf_set]
original["track_ids"] = base_order + extra
# Settings from newer file
if "settings" in conflict:
original["settings"] = conflict["settings"]
order_src = "the other machine"
else:
# Original is newer — append missing from conflict
extra = [tid for tid in conflict.get("track_ids", []) if tid not in orig_ids]
original["track_ids"] = original.get("track_ids", []) + extra
extra = [tid for tid in conf_ids if tid not in orig_set]
original["track_ids"] = orig_ids + extra
order_src = "this machine"
_save_json(original_path, original)
def _merge_metadata(original_path: Path, conflict_path: Path):
# Simple: keep the newer file's content
_keep_newer(original_path, conflict_path)
added = len(set(original["track_ids"]) - orig_set)
lines = [f"Order kept from {order_src} (most recently edited)."]
if added:
lines.append(f"{added} track(s) that were only in the other copy were kept "
"(nothing is removed on a merge).")
return ConflictSummary(name, "playlist", lines)
def _keep_newer(original_path: Path, conflict_path: Path):
def _merge_metadata(original_path: Path, conflict_path: Path) -> ConflictSummary:
summary = _keep_newer(original_path, conflict_path)
summary.file, summary.kind = "library_metadata.json", "metadata"
summary.lines = ["Library columns/settings taken from the most recently edited copy."]
return summary
def _keep_newer(original_path: Path, conflict_path: Path) -> ConflictSummary:
took = "this machine"
if conflict_path.stat().st_mtime > original_path.stat().st_mtime:
shutil.copy2(conflict_path, original_path)
took = "the other machine"
return ConflictSummary(original_path.name, "other",
[f"Kept the copy from {took} (most recently edited)."])
def _archive(conflict_path: Path, resolved_dir: Path):
timestamp = datetime.now().strftime("%Y%m%d-%H%M%S")
archive_name = f"{timestamp}_{conflict_path.name}"
shutil.move(str(conflict_path), str(resolved_dir / archive_name))
def _stars(rating) -> str:
try:
return f"{int(rating) // 20}"
except (TypeError, ValueError):
return "0★"
def _copy(src: Path, dest: Path):
dest.parent.mkdir(parents=True, exist_ok=True)
shutil.copy2(src, dest)
def _load_json(path: Path) -> dict:
@ -168,5 +260,7 @@ def _load_json(path: Path) -> dict:
def _save_json(path: Path, data: dict):
with open(path, "w", encoding="utf-8") as f:
tmp = path.with_suffix(path.suffix + ".tmp")
with open(tmp, "w", encoding="utf-8") as f:
json.dump(data, f, indent=2, ensure_ascii=False)
tmp.replace(path)