fix: prune log_dir on every roll so daily/size retention is enforced

TimedRotatingFileHandler/RotatingFileHandler retention (getFilesToDelete) only scans the live file's directory, never the log_dir we redirect rolled files into, so daily (the default) and size modes never pruned and .gz files grew unbounded. the rotator now calls the existing prune(log_dir, stem, backup_count) helper (the one on_start already uses) after each roll. verified by execution: daily and size both retain exactly backup_count; a no-prune control retains all.

Signed-off-by: disqualifier <dev@disqualifier.me>

src/log_setup/rotation.py

@@ -10,7 +10,7 @@ import gzip
 import os
 import shutil
 import time
-from typing import Callable, Tuple
+from typing import Callable, Optional, Tuple
 
 
 def make_namer(log_dir: str, compress: bool) -> Callable[[str], str]:
@@ -26,8 +26,18 @@ def make_namer(log_dir: str, compress: bool) -> Callable[[str], str]:
     return namer
 
 
-def make_rotator(compress: bool) -> Callable[[str, str], None]:
-    """rotator: move (or gzip) the source live file to the destination rolled path"""
+def make_rotator(
+    compress: bool, log_dir: Optional[str] = None,
+    prune_stem: Optional[str] = None, backup_count: int = 0,
+) -> Callable[[str, str], None]:
+    """rotator: move (or gzip) the source live file to the destination rolled path
+
+    prunes `log_dir` to `backup_count` newest rolled files after each roll when
+    `log_dir`/`prune_stem` are given. the stdlib handler's own retention
+    (`getFilesToDelete`) only scans the live file's directory, so it never sees the
+    rolled files we redirect into `log_dir` — pruning here is what actually bounds
+    retention for the daily and size rolling modes.
+    """
     def rotator(source: str, dest: str) -> None:
         if not os.path.exists(source):
             return
@@ -37,6 +47,8 @@ def make_rotator(compress: bool) -> Callable[[str, str], None]:
             os.remove(source)
         else:
             os.replace(source, dest)
+        if log_dir is not None and prune_stem is not None:
+            prune(log_dir, prune_stem, backup_count)
     return rotator
 
 
@@ -93,10 +105,17 @@ def _safe_mtime(path: str) -> float:
         return 0.0
 
 
-def attach_rolling(handler, log_dir: str, compress: bool) -> Tuple[Callable, Callable]:
-    """wire the custom namer + rotator onto a rotating handler; return them"""
+def attach_rolling(
+    handler, log_dir: str, compress: bool,
+    prune_stem: Optional[str] = None, backup_count: int = 0,
+) -> Tuple[Callable, Callable]:
+    """wire the custom namer + rotator onto a rotating handler; return them
+
+    pass `prune_stem`/`backup_count` so the rotator prunes `log_dir` after each roll
+    (the handler's own retention can't see the redirected rolled files).
+    """
     namer = make_namer(log_dir, compress)
-    rotator = make_rotator(compress)
+    rotator = make_rotator(compress, log_dir, prune_stem, backup_count)
     handler.namer = namer
     handler.rotator = rotator
     return namer, rotator

src/log_setup/setup.py

@@ -66,12 +66,12 @@ def _file_handler(
         handler = logging.handlers.RotatingFileHandler(
             live_path, maxBytes=max_bytes, backupCount=backup_count, encoding="utf-8",
         )
-        attach_rolling(handler, log_dir, compress)
+        attach_rolling(handler, log_dir, compress, prune_stem=name, backup_count=backup_count)
     elif rotate == "daily":
         handler = logging.handlers.TimedRotatingFileHandler(
             live_path, when="midnight", backupCount=backup_count, encoding="utf-8",
         )
-        attach_rolling(handler, log_dir, compress)
+        attach_rolling(handler, log_dir, compress, prune_stem=name, backup_count=backup_count)
     else:
         if rotate == "on_start":
             rotate_on_start(live_path, log_dir, compress)