Critical fixes:
- Separate notification and command connections to eliminate dual-reader
race condition on the TCL RPC stream (C-1)
- Fix _get_or_create_loop() swallowing its own RuntimeError, causing
deadlock when sync API called from async context (C-2)
- Add bounds checking to config string parser (C-3)
- Clean up OpenOCD subprocess on connection failure in Session.start (H-1)
Defense in depth:
- Add MAX_RESPONSE_SIZE (10MB) guard against unbounded buffer growth
- Preserve bytes after separator in _read_until_separator remainder buffer
- Set notification_failed flag when listener crashes, warn on next send
- Standardize error detection to case-insensitive across all modules
- Escape TCL special characters in RTT channelwrite to prevent injection
- Redirect OpenOCD stdout to DEVNULL to prevent pipe buffer deadlock
- Run SVD XML parsing in asyncio.to_thread to avoid blocking event loop
Consistency:
- Cache SyncSession subsystem wrappers (match async Session pattern)
- Make DecodedRegister frozen (match all other dataclasses)
- Add py.typed marker for PEP 561 type checker support
- Accept list[str] config in OpenOCDProcess.start for paths with spaces
Tests:
- Add 50 error-path tests covering connection, target, memory, register,
flash, breakpoint, session, process, and notification failure modes
