feat(logging): archive historical logs daily into Archive/

At startup, previously produced logs are relocated into an Archive/
subfolder next to the active log: the project sync.log gets a
-YYYY-MM-DD suffix when archived, and NSSM's nssm_*.log captures are
moved as-is. The log root then only shows the current day's sync.log.
Idempotent handler setup is preserved.

Co-Authored-By: WorkBuddy <workbuddy@tencent.com>

src/sync/logging_setup.py

@@ -2,10 +2,89 @@
 
 Configures the root logger with a RotatingFileHandler (10 MB x 5, UTF-8) plus
 a console StreamHandler. The level and log path come from ``cfg.logging``.
+
+Log files are managed per-day: at startup any previously produced log
+(including the project's own ``sync.log`` and NSSM's ``nssm_*.log`` captures)
+is relocated into an ``Archive/`` subfolder next to the active log. Where a log
+lacks a timestamp, a ``-YYYY-MM-DD`` suffix is added (derived from its first
+log line, falling back to mtime) so historical files carry a date. The log
+root therefore only ever shows the current day's ``sync.log``.
 """
+import datetime
 import logging
 import logging.handlers
 import os
+import re
+import shutil
+
+
+_LOG_DATE_RE = re.compile(r"^(\d{4}-\d{2}-\d{2})")
+
+
+def _first_line_date(path: str) -> str | None:
+    """Best-effort extraction of the first log line's YYYY-MM-DD date."""
+    try:
+        with open(path, "r", encoding="utf-8", errors="replace") as f:
+            for line in f:
+                m = _LOG_DATE_RE.match(line)
+                if m:
+                    return m.group(1)
+    except OSError:
+        pass
+    return None
+
+
+def _archive_completed_logs(log_dir: str, active_name: str):
+    """Move already-produced logs out of *log_dir* into *log_dir*/Archive.
+
+    The active log (*active_name*) is left in place only when it belongs to the
+    current day; an older ``sync.log`` is archived (with a ``-YYYY-MM-DD``
+    suffix) so a fresh one can be opened. NSSM's own ``nssm_*.log`` captures are
+    timestamped already and are moved as-is. Moves are best-effort: files locked
+    by another process (e.g. NSSM's live handles) are skipped.
+    """
+    archive_dir = os.path.join(log_dir, "Archive")
+    os.makedirs(archive_dir, exist_ok=True)
+    today = datetime.date.today()
+
+    for name in os.listdir(log_dir):
+        src = os.path.join(log_dir, name)
+        if not os.path.isfile(src):
+            continue
+        if name == "Archive":
+            continue
+        if not (name.endswith(".log") or ".log." in name):
+            continue
+        # Keep NSSM's live, currently-open handles in place.
+        if name in ("nssm_stderr.log", "nssm_stdout.log"):
+            continue
+
+        if name == active_name:
+            # Only archive the active log if it is from a previous day.
+            log_date = _first_line_date(src)
+            log_date = (
+                datetime.date.fromisoformat(log_date)
+                if log_date
+                else datetime.date.fromtimestamp(os.path.getmtime(src))
+            )
+            if log_date >= today:
+                continue  # today's log: keep appending
+            new_name = f"sync-{log_date.strftime('%Y-%m-%d')}.log"
+        else:
+            new_name = name
+
+        dst = os.path.join(archive_dir, new_name)
+        if os.path.exists(dst):
+            stem, ext = os.path.splitext(new_name)
+            i = 2
+            while os.path.exists(os.path.join(archive_dir, f"{stem}({i}){ext}")):
+                i += 1
+            dst = os.path.join(archive_dir, f"{stem}({i}){ext}")
+        try:
+            shutil.move(src, dst)
+        except OSError:
+            # Locked by another process (e.g. NSSM holding the file open).
+            pass
 
 
 def setup_logging(cfg_dict: dict | None):
@@ -13,11 +92,16 @@ def setup_logging(cfg_dict: dict | None):
 
     ``cfg_dict`` is ``SyncConfig.logging`` (a dict or None). ``level`` is a
     logging-level name string (default ``"INFO"``); ``path`` is the log file
-    path (default ``"sync.log"``). The parent directory is created if missing.
+    path (default ``"sync.log"``). The parent directory is created if missing,
+    and any previously produced logs are archived before the new handler opens.
     """
     level = getattr(logging, (cfg_dict or {}).get("level", "INFO")) if cfg_dict else logging.INFO
     path = (cfg_dict or {}).get("path", "sync.log")
-    os.makedirs(os.path.dirname(path) or ".", exist_ok=True)
+    log_dir = os.path.dirname(path) or "."
+    os.makedirs(log_dir, exist_ok=True)
+
+    # Archive everything from prior runs so the root only shows today's log.
+    _archive_completed_logs(log_dir, os.path.basename(path))
 
     # Idempotent: drop any handlers already attached to the root logger before
     # re-adding. setup_logging can be called from more than one entry point