Deprecate specifying a model name without a provider prefix, and the vertexai provider name (#2711)

Author: DouweM

docs/logfire.md

@@ -297,7 +297,7 @@ instrumentation_settings = InstrumentationSettings(
     event_logger_provider=EventLoggerProvider(),
 )
 
-agent = Agent('gpt-4o', instrument=instrumentation_settings)
+agent = Agent('openai:gpt-4o', instrument=instrumentation_settings)
 # or to instrument all agents:
 Agent.instrument_all(instrumentation_settings)
 ```
@@ -309,7 +309,7 @@ from pydantic_ai import Agent
 from pydantic_ai.models.instrumented import InstrumentationSettings, InstrumentedModel
 
 settings = InstrumentationSettings()
-model = InstrumentedModel('gpt-4o', settings)
+model = InstrumentedModel('openai:gpt-4o', settings)
 agent = Agent(model)
 ```
 
@@ -320,7 +320,7 @@ from pydantic_ai.agent import Agent, InstrumentationSettings
 
 instrumentation_settings = InstrumentationSettings(include_binary_content=False)
 
-agent = Agent('gpt-4o', instrument=instrumentation_settings)
+agent = Agent('openai:gpt-4o', instrument=instrumentation_settings)
 # or to instrument all agents:
 Agent.instrument_all(instrumentation_settings)
 ```
@@ -337,7 +337,7 @@ from pydantic_ai.models.instrumented import InstrumentationSettings
 
 instrumentation_settings = InstrumentationSettings(include_content=False)
 
-agent = Agent('gpt-4o', instrument=instrumentation_settings)
+agent = Agent('openai:gpt-4o', instrument=instrumentation_settings)
 # or to instrument all agents:
 Agent.instrument_all(instrumentation_settings)
 ```

docs/multi-agent-applications.md

@@ -106,7 +106,7 @@ joke_selection_agent = Agent(
     ),
 )
 joke_generation_agent = Agent(
-    'gemini-1.5-flash',
+    'google-gla:gemini-1.5-flash',
     deps_type=ClientAndKey,  # (4)!
     output_type=list[str],
     system_prompt=(

pydantic_ai_slim/pydantic_ai/models/__init__.py

@@ -7,6 +7,7 @@
 from __future__ import annotations as _annotations
 
 import base64
+import warnings
 from abc import ABC, abstractmethod
 from collections.abc import AsyncIterator, Iterator
 from contextlib import asynccontextmanager, contextmanager
@@ -684,19 +685,29 @@ def infer_model(model: Model | KnownModelName | str) -> Model:  # noqa: C901
     try:
         provider, model_name = model.split(':', maxsplit=1)
     except ValueError:
+        provider = None
         model_name = model
-        # TODO(Marcelo): We should deprecate this way.
         if model_name.startswith(('gpt', 'o1', 'o3')):
             provider = 'openai'
         elif model_name.startswith('claude'):
             provider = 'anthropic'
         elif model_name.startswith('gemini'):
             provider = 'google-gla'
+
+        if provider is not None:
+            warnings.warn(
+                f"Specifying a model name without a provider prefix is deprecated. Instead of {model_name!r}, use '{provider}:{model_name}'.",
+                DeprecationWarning,
+            )
         else:
             raise UserError(f'Unknown model: {model}')
 
-    if provider == 'vertexai':
-        provider = 'google-vertex'  # pragma: no cover
+    if provider == 'vertexai':  # pragma: no cover
+        warnings.warn(
+            "The 'vertexai' provider name is deprecated. Use 'google-vertex' instead.",
+            DeprecationWarning,
+        )
+        provider = 'google-vertex'
 
     if provider == 'cohere':
         from .cohere import CohereModel

tests/models/test_model.py

@@ -1,3 +1,4 @@
+import warnings
 from importlib import import_module
 
 import pytest
@@ -124,7 +125,9 @@ def test_infer_model(
     try:
         model_module = import_module(f'pydantic_ai.models.{module_name}')
         expected_model = getattr(model_module, model_class_name)
-        m = infer_model(model_name)
+        with warnings.catch_warnings():
+            warnings.simplefilter('ignore', DeprecationWarning)
+            m = infer_model(model_name)
     except ImportError:
         pytest.skip(f'{model_name} dependencies not installed')
 

tests/test_cli.py

@@ -106,7 +106,7 @@ def test_agent_flag_set_model(
 
     mocker.patch('pydantic_ai._cli.ask_agent')
 
-    assert cli(['--agent', 'test_module:custom_agent', '--model', 'gpt-4o', 'hello']) == 0
+    assert cli(['--agent', 'test_module:custom_agent', '--model', 'openai:gpt-4o', 'hello']) == 0
 
     assert 'using custom agent test_module:custom_agent with openai:gpt-4o' in capfd.readouterr().out.replace('\n', '')