…sues

  Threading & concurrency (moonrakerComm.py):
  - Move class-level state vars (connected/connecting/_reconnect_count/callback_table)
    into __init__ to prevent shared state across instances
  - Add _state_lock (RLock) and _request_lock guarding all reads/writes to those vars
  - Fix mutable default dict in send_request (params={} → params=None)
  - Fix unbound super() in OneShotTokenError (__init__ without class arg)
  - Guard _retry_timer with None before stopTimer/startTimer calls; stop existing
    timer in try_connection before creating a new one (prevents orphaned threads)
  - sendEvent → postEvent for cross-thread event delivery
  - Wrap json.loads in try/except; use .get() on all external response dicts
  - Fix dest_dir guard (False → None) in copy/move file; fix machine.update.client
    missing params dict; fix machine.update.rollback method typo (comma → dot)
  - Add klippy startup/disconnected retry cap (30 attempts) to prevent infinite loop
  - Add join(timeout=self.timeout+1) on _wst to avoid indefinite block

  RepeatedTimer: fix inverted stopEvent semantics (set=stop, clear=running)

  Pi runtime crashes:
  - cancelPage: fix AttributeError on file_metadata dict access
  - connectionPage: fix stale slot name
  - inputshaperPage: fix uninitialized currentItem reference
  - mainWindow: fix _handle_notify (dict.popitem → next(iter(items())));
    fix global_back tab-bar gate; fix logger f-string
  - filamentTab: fix slot signature mismatch; fix stale _is_printing state;
    fix bare self.isVisible reference (missing parentheses)
  - jobStatusPage: use separate event_state var (never reassign lstate);
    capture file locals before clearing state; print_finish only on complete;
    layer fallback uses Mainsail ceil formula; layer_fallback flag decoupled
    from total_layer
  - sensorsPanel: removeWidget+deleteLater before clearing tracking dict on
    reconnect to prevent widget stacking
  - babystepPage: label sync with confirmed Klipper value, button reorder,
    code deduplication
  - probeHelperPage: only process is_active when key present in update dict
    (Klipper sends position-only partial updates after TESTZ)
  - screensaver: guard DPMS calls with hasattr(_dpms_available) check

  Python 3.11 typing (20 files):
  - Optional/Union/List/Dict → native syntax; add from __future__ import annotations
  - filament.brand setter: return type None; _spool_type initialized in __init__
  - files.py: remove duplicate ReceivedFileData import; use events.ReceivedFileData

  helper_methods:
  - convert_bytes_to_mb: remove spurious self param; rename bytes → size_bytes
  - calculate_current_layer: Mainsail formula (ceil((z-first)/layer+1)), clamped
  - calculate_max_layers: extracted from calculate_current_layer; max(1,...) guard
  - normalize, check_filepath_permission, check_dir_existence: pathlib + type hints
  - estimate_print_time: modernized variable names and return type annotation
  - Remove unused get_file_loc/digest_hash stubs; remove normalize import from
    controlTab and tunePage

  controlTab/tunePage slider split:
  - controlTab.on_slider_change: handles fan_generics only (SET_FAN_SPEED)
  - tunePage: _on_speed_slider_change for print speed (M220) and on_slider_change
    for fan_generics — eliminates collision when fan is named speed

…ugfix/crash-history