Required by Phase 10 migrations which call these from_dict methods.
Without these, CustomSlice.from_dict() and MMAUsageStats.from_dict()
used in gui_2.py would raise AttributeError at runtime.
Adds the from_dict pattern consistent with the existing
CommsLogEntry/HistoryMessage/ToolDefinition from_dict:
- Filter dict keys to only the dataclass fields (ignore extras)
- Pass filtered dict to cls(**filtered)
Field definitions unchanged. No-op behavior for callers that
already have a dataclass instance (they pass through isinstance check).
Tests: 51/51 pass across all related test files.
ed
e508758fbe