Infrastructure change required by Phase 5/6/7 of the
type_alias_unfuck_20260626 track. The plan's migration pattern
(var = Aggregate.from_dict(var)) requires from_dict on the
target dataclasses. None existed for the openai_schemas
classes, so this commit adds them.
from_dict semantics:
- Filter dict keys to only the dataclass fields (ignore extra keys
like _est_tokens)
- For ChatMessage: convert nested tool_calls list to tuple of ToolCall
- For ToolCall: convert nested function dict to ToolCallFunction
- For UsageStats: direct field mapping
Field definitions unchanged. Behavior: zero impact on existing tests
(no callers exist yet for from_dict on these classes).
Tests: syntax check OK; manual instantiation confirms from_dict works.
ed
1b62659c8c