Make chat and embed interfaces provider-agnostic using pydantic_ai

[gvanrossum]

Support multiple AI providers via pydantic_ai

• New model_adapters.py: create_chat_model(),
  create_embedding_model(), and configure_models() accept
  "provider:model" specs (e.g. "anthropic:claude-sonnet-4-20250514"),
  delegating to pydantic_ai's 25+ provider registry.
• New IEmbedder protocol (two async methods) replaces the
  monolithic AsyncEmbeddingModel class; CachingEmbeddingModel
  wraps any IEmbedder with cache logic.
• Removed: AsyncEmbeddingModel, ModelWrapper,
  create_typechat_model(), hardcoded embedding_size,
  max_retries, and model_registry.py.
• Azure auto-fallback preserved; new OPENAI_EMBEDDING_MODEL
  env var; create_test_embedding_model() for tests.

[bmerkle]

pyproject.toml or lockfile was not touched so the dependecy to pydantic_ai is missing.

[bmerkle]

the pydantic.ai API uses a ctor call to instantiate models or agents and not a method so this looks kind of strange.
e.g.

model = os.getenv('PYDANTIC_AI_MODEL', 'openai:gpt-5.2')
print(f'Using model: {model}')
agent = Agent(model, output_type=MyModel)

[gvanrossum]

the pydantic.ai API uses a ctor call to instantiate models or agents and not a method so this looks kind of strange.

I don't understand your comment. This is the (new) idiomatic way to create an embedding model. Unless there's already an embedding model available in the settings?

[gvanrossum]

pyproject.toml or lockfile was not touched so the dependecy to pydantic_ai is missing.

Fixed.

[bmerkle]

found another issue, not from this PR, but we should fix before release:

will fix this in the bugfix branch

src\typeagent\knowpro\interfaces_search.py
contains two all lists. IMO we should delete one :-) (line 147 or 20)

__all__ = [
    "KnowledgePropertyName",
    "PropertySearchTerm",
    "SearchSelectExpr",
    "SearchTerm",
    "SearchTermGroup",
    "SearchTermGroupTypes",
    "SemanticRefSearchResult",
    "WhenFilter",
]

typeagent-py/src/typeagent/knowpro/interfaces_search.py

Line 20 in d26dc13

__all__ = [

typeagent-py/src/typeagent/knowpro/interfaces_search.py

Line 147 in d26dc13

__all__ = [

[bmerkle]

LGTM, please merge to main