Keep crash-log streams open until fault handling stops

agent-notes/improve-crash-lifetime.md

@@ -0,0 +1,19 @@
+# Goal
+
+Keep fatal traceback output attached to an open error-log stream through shutdown.
+
+# State
+
+Pass the existing error-handler stream directly to faulthandler. Remove the wrapper that only forwarded fileno. Package shutdown and an exit callback disable package-enabled fault handling before logging closes its files. This PR is independently based on integrated master and contains no UTF-8 PR commits.
+
+# Decisions and why
+
+faulthandler retains a file descriptor, not a logging handler. Its stream must stay open until fault handling is disabled. The exit callback runs before logging's earlier registered shutdown callback. Disabling is a no-op when this package has not enabled fault handling. Fatal dumps remain raw output rather than formatted log records.
+
+# Surprises
+
+The removed StreamToLogger never redirected log writes; its description was misleading.
+
+# Next step
+
+Read this PR's existing package checks. Subsequent setup/reconfiguration changes must retain the same file-lifetime ordering. No merge or release.

logger_setup/crashlogger.py

@@ -1,21 +1,22 @@
-import logging
+import atexit
 import faulthandler
 
-CRASHLOGGER_NAME = "APPCRASH"
+_enabled = False
 
 
-class StreamToLogger(object):
-    """
- Fake file-like stream object that redirects writes to a logger instance.
- """
+def enable_crashlogger(error_handler):
+    global _enabled
+    faulthandler.enable(error_handler.stream)
+    _enabled = True
 
-    def __init__(self, handler):
-        self.handler = handler
 
-    def fileno(self):
-        return self.handler.stream.fileno()
+def disable_crashlogger():
+    global _enabled
+    if _enabled:
+        faulthandler.disable()
+        _enabled = False
 
 
-def enable_crashlogger(error_handler):
-    stream = StreamToLogger(error_handler)
-    faulthandler.enable(stream)
+# logging registers its shutdown before importing this module. Exit callbacks
+# run in reverse order, so release the fault descriptor before logs are closed.
+atexit.register(disable_crashlogger)

logger_setup/logger_setup.py

@@ -86,4 +86,5 @@ def setup_logging(
 
 
 def shutdown():
+    crashlogger.disable_crashlogger()
     logging.shutdown()