[Cosmos] reformat availability_strategy use (#45141)

* address missing comments

* Update CHANGELOG.md

* Update sdk/cosmos/azure-cosmos/azure/cosmos/container.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Delete fix_docstrings.py

* Apply suggestion from @simorenoh

* Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* fixing copilot miss

* update usage to bool/dict

* Update CHANGELOG.md

* Update test_availability_strategy.py

* fixing weird additional logic

* Update README.md

* mypy pylint

* Update _request_object.py

* Update _request_object.py

* more changes

* add client verification method, mypy

* update docs

* Update CHANGELOG.md

* Update README.md

* Update README.md

* typings

* Update cosmos_client.py

* test fixes

* Update CHANGELOG.md

* update behavior for True on request level

* logic updates

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: simorenoh

sdk/cosmos/azure-cosmos/CHANGELOG.md

@@ -1,6 +1,6 @@
 ## Release History
 
-### 4.15.0 (2026-02-11)
+### 4.15.0 (2026-02-19)
 
 #### Features Added
 * GA support of Per Partition Automatic Failover and AvailabilityStrategy features.
@@ -13,6 +13,7 @@
 #### Other Changes
 * Added tests for multi-language support for full text search. See [PR 44254](https://github.com/Azure/azure-sdk-for-python/pull/44254)
 * Renamed `availability_strategy_config` introduced in 4.15.0b1 to `availability_strategy` for both sync and async clients. See [PR 45086](https://github.com/Azure/azure-sdk-for-python/pull/45086).
+* Request-level `availability_strategy` needs to be set to `False` in order to disable availability strategy for that request, as opposed to setting it to `None`. See [PR 45141](https://github.com/Azure/azure-sdk-for-python/pull/45141).
 
 ### 4.14.6 (2026-02-02)
 

sdk/cosmos/azure-cosmos/README.md

@@ -952,13 +952,28 @@ Cross region hedging availability strategy improves availability and reduces lat
 
 #### Enabling Cross Region Hedging
 
-You can enable cross region hedging by passing the `availability_strategy` parameter as a dictionary to the `CosmosClient` or per-request. The most common configuration keys are `threshold_ms` (delay before sending a hedged request) and `threshold_steps_ms` (step interval for additional hedged requests).
+You can enable cross region hedging by passing the `availability_strategy` parameter to the `CosmosClient` or per-request. This parameter accepts:
+
+- **`True`**: Enable hedging with default values (`threshold_ms=500`, `threshold_steps_ms=100`) or override client settings to this default at the request level.
+- **`False`**: Explicitly disable hedging at the client or request level (overrides client-level settings)
+- **`dict`**: Enable hedging with custom values. The keys are `threshold_ms` (delay before sending a hedged request) and `threshold_steps_ms` (step interval for additional hedged requests). Missing keys will use default values.
+- **`None`**: Default value only usable at the request level. Use the client-level configurations.
+
+Hedging will also be implicitly enabled when per-partition automatic failover is enabled, in which case the `CrossRegionHedgingStrategy` applies the default values outlined above of 500 ms for `threshold_ms` and 100 ms for `threshold_steps_ms` unless you override them via `availability_strategy`.
 
 #### Client-level configuration
 
 ```python
 from azure.cosmos import CosmosClient
 
+# Enable with default values
+client = CosmosClient(
+    "<account-uri>",
+    "<account-key>",
+    availability_strategy=True
+)
+
+# Enable with custom values
 client = CosmosClient(
     "<account-uri>",
     "<account-key>",
@@ -969,12 +984,19 @@ client = CosmosClient(
 #### Request-level configuration
 
 ```python
-# Override or provide the strategy per request
+# Override or provide the strategy per request with custom values
 container.read_item(
     item="item_id",
     partition_key="pk_value",
     availability_strategy={"threshold_ms": 150, "threshold_steps_ms": 50}
 )
+
+# Enable with default values for a specific request
+container.read_item(
+    item="item_id",
+    partition_key="pk_value",
+    availability_strategy=True
+)
 ```
 
 #### Disable availability strategy on request level
@@ -984,7 +1006,7 @@ container.read_item(
 container.read_item(
     item="item_id",
     partition_key="pk_value",
-    availability_strategy=None
+    availability_strategy=False
 )
 ```
 
@@ -999,25 +1021,41 @@ executor = ThreadPoolExecutor(max_workers=2)
 client = CosmosClient(
     "<account-uri>",
     "<account-key>",
-    availability_strategy={"threshold_ms": 150, "threshold_steps_ms": 50},
+    availability_strategy=True,  # or use a dict for custom values
     availability_strategy_executor=executor
 )
 ```
 
 #### Customized max concurrency for hedging for async client
 
 ```python
-# Customize the max concurrency on the default ThreadPoolExecutor for the sync client
-from azure.cosmos import CosmosClient
+# Customize the max concurrency for the async client
+from azure.cosmos.aio import CosmosClient
 
 client = CosmosClient(
     "<account-uri>",
     "<account-key>",
-    availability_strategy={"threshold_ms": 150, "threshold_steps_ms": 50},
+    availability_strategy=True,  # or use a dict for custom values
     availability_strategy_max_concurrency=2
 )
 ```
 
+### Cross Region Hedging - Best Practices
+
+1. Configure appropriate thresholds based on your application's needs:
+   - Lower thresholds: More aggressive hedging, potentially higher costs
+   - Higher thresholds: More conservative, may impact latency
+
+2. Use request-level overrides judiciously:
+   - Disable hedging for non-critical operations
+   - Use custom thresholds for latency-sensitive operations
+
+3. Monitor usage:
+   - Track hedging patterns
+   - Adjust thresholds based on observed performance
+
+4. Enable multiple write regions when write availability is critical
+
 ## Troubleshooting
 
 ### General

sdk/cosmos/azure-cosmos/azure/cosmos/_availability_strategy_config.py

@@ -21,7 +21,11 @@
 
 """Configuration types for Azure Cosmos DB availability strategies."""
 
-from typing import Optional, Any
+from typing import Optional, Any, Union
+
+# Default values for cross-region hedging strategy
+DEFAULT_THRESHOLD_MS = 500
+DEFAULT_THRESHOLD_STEPS_MS = 100
 
 
 class CrossRegionHedgingStrategy:
@@ -37,26 +41,59 @@ class CrossRegionHedgingStrategy:
     """
     def __init__(self, config: Optional[dict[str, Any]] = None) -> None:
         if config is None:
-            self.threshold_ms = 500
-            self.threshold_steps_ms = 100
+            self.threshold_ms = DEFAULT_THRESHOLD_MS
+            self.threshold_steps_ms = DEFAULT_THRESHOLD_STEPS_MS
         else:
-            self.threshold_ms = config.get("threshold_ms", 500)
-            self.threshold_steps_ms = config.get("threshold_steps_ms", 100)
+            self.threshold_ms = config.get("threshold_ms", DEFAULT_THRESHOLD_MS)
+            self.threshold_steps_ms = config.get("threshold_steps_ms", DEFAULT_THRESHOLD_STEPS_MS)
 
         if self.threshold_ms <= 0:
             raise ValueError("threshold_ms must be positive")
         if self.threshold_steps_ms <= 0:
             raise ValueError("threshold_steps_ms must be positive")
 
-def _validate_hedging_strategy(config: Optional[dict[str, Any]]) -> Optional[CrossRegionHedgingStrategy]:
-    """Validate and create a CrossRegionHedgingStrategy.
+
+def _validate_request_hedging_strategy(
+        config: Optional[Union[bool, dict[str, Any]]]
+) -> Union[CrossRegionHedgingStrategy, bool, None]:
+    """Validate and create a CrossRegionHedgingStrategy for a request.
     
-    :param config: Dictionary containing configuration values
-    :type config: Optional[Dict[str, Any]]
-    :returns: Validated configuration object
-    :rtype: Optional[CrossRegionHedgingStrategy]
+    :param config: Configuration for availability strategy. Can be:
+        - None: Returns None (no strategy, uses client default if available)
+        - True: Returns strategy with default values (threshold_ms=500, threshold_steps_ms=100)
+        - False: Returns False (explicitly disabled, overrides client configs)
+        - dict: Returns strategy with values from dict, using defaults for missing keys
+    :type config: Optional[Union[bool, Dict[str, Any]]]
+    :returns: Validated configuration object, False if explicitly disabled, or None
+    :rtype: Union[CrossRegionHedgingStrategy, bool, None]
+    """
+    if isinstance(config, dict):
+        # Validate dict values by attempting to create a strategy object
+        return CrossRegionHedgingStrategy(config)
+    # For bool and None, no validation needed as they are handled in the request object's `set_availability_strategy`
+    return config
+
+
+def validate_client_hedging_strategy(
+        config: Union[bool, dict[str, Any]]
+) -> Union[CrossRegionHedgingStrategy, None]:
+    """Validate and create a CrossRegionHedgingStrategy for the client.
+
+    :param config: Configuration for availability strategy. Can be:
+        - True: Returns strategy with default values (threshold_ms=500, threshold_steps_ms=100)
+        - False: Returns False (default, explicitly disabled)
+        - dict: Returns strategy with values from dict, using defaults for missing keys
+    :type config: Union[bool, Dict[str, Any]]
+    :returns: Validated configuration object, False if explicitly disabled, or None
+    :rtype: Union[CrossRegionHedgingStrategy, None]
     """
-    if config is None:
+
+    if isinstance(config, bool):
+        if config:
+            # True -> use default values
+            return CrossRegionHedgingStrategy()
+        # False -> nothing set by client, return None to allow request level override or default to no strategy
         return None
 
+    # dict -> use values from dict
     return CrossRegionHedgingStrategy(config)

sdk/cosmos/azure-cosmos/azure/cosmos/_cosmos_client_connection.py

@@ -48,7 +48,7 @@
 from azure.core.utils import CaseInsensitiveDict
 
 from . import _base as base
-from .user_agent_policy import CosmosUserAgentPolicy
+from ._user_agent_policy import CosmosUserAgentPolicy
 from ._global_partition_endpoint_manager_per_partition_automatic_failover import _GlobalPartitionEndpointManagerForPerPartitionAutomaticFailover # pylint: disable=line-too-long
 from . import _query_iterable as query_iterable
 from . import _runtime_constants as runtime_constants
@@ -58,7 +58,7 @@
 from . import documents
 from . import http_constants, exceptions
 from ._auth_policy import CosmosBearerTokenCredentialPolicy
-from ._availability_strategy_config import _validate_hedging_strategy, CrossRegionHedgingStrategy
+from ._availability_strategy_config import validate_client_hedging_strategy, CrossRegionHedgingStrategy
 from ._base import _build_properties_cache
 from ._change_feed.change_feed_iterable import ChangeFeedIterable
 from ._change_feed.change_feed_state import ChangeFeedState
@@ -119,7 +119,7 @@ def __init__( # pylint: disable=too-many-statements
         auth: CredentialDict,
         connection_policy: Optional[ConnectionPolicy] = None,
         consistency_level: Optional[str] = None,
-        availability_strategy: Optional[dict[str, Any]] = None,
+        availability_strategy: Union[bool, dict[str, Any]] = False,
         availability_strategy_executor: Optional[ThreadPoolExecutor] = None,
         **kwargs: Any
     ) -> None:
@@ -145,8 +145,8 @@ def __init__( # pylint: disable=too-many-statements
         """
         self.client_id = str(uuid.uuid4())
         self.url_connection = url_connection
-        self.availability_strategy: Optional[CrossRegionHedgingStrategy] =\
-            _validate_hedging_strategy(availability_strategy)
+        self.availability_strategy: Union[CrossRegionHedgingStrategy, None] =\
+            validate_client_hedging_strategy(availability_strategy)
         self.availability_strategy_executor: Optional[ThreadPoolExecutor] = availability_strategy_executor
         self.master_key: Optional[str] = None
         self.resource_tokens: Optional[Mapping[str, Any]] = None

sdk/cosmos/azure-cosmos/azure/cosmos/_request_object.py

@@ -114,21 +114,36 @@ def set_excluded_locations_from_circuit_breaker(self, excluded_locations: list[s
     def set_availability_strategy(
             self,
             options: Mapping[str, Any],
-            client_strategy_config: Optional[CrossRegionHedgingStrategy] = None) -> None:
+            client_strategy_config: Union[CrossRegionHedgingStrategy, None] = None) -> None:
         """Sets the availability strategy config for this request from options.
         If not in options, uses the client's default strategy.
+        If False is in options, client defaults are NOT used (explicitly disabled).
 
         :param options: The request options that may contain availabilityStrategy
         :type options: Mapping[str, Any]
         :param client_strategy_config: The client's default availability strategy config
-        :type client_strategy_config: ~azure.cosmos.CrossRegionHedgingStrategyConfig
+        :type client_strategy_config: Union[CrossRegionHedgingStrategy, None]
         :return: None
         """
         # setup availabilityStrategy
-        # First try to get from options
-        if Constants.Kwargs.AVAILABILITY_STRATEGY in options:
-            self.availability_strategy = options[Constants.Kwargs.AVAILABILITY_STRATEGY]
-        # If not in options, use client default
+        # First try to get from options (method-level takes precedence)
+        if (Constants.Kwargs.AVAILABILITY_STRATEGY in options and
+                options[Constants.Kwargs.AVAILABILITY_STRATEGY] is not None):
+            strategy = options[Constants.Kwargs.AVAILABILITY_STRATEGY]
+            if isinstance(strategy, bool):
+                if strategy:
+                    # If True, use client config if available, otherwise default values
+                    if client_strategy_config is not None:
+                        self.availability_strategy = client_strategy_config
+                    else:
+                        self.availability_strategy = CrossRegionHedgingStrategy()
+                # If False, user explicitly disabled - don't use any strategy
+                else:
+                    self.availability_strategy = None
+            else:
+                # CrossRegionHedgingStrategy object from request validation
+                self.availability_strategy = strategy
+        # If not in options or None within options, use client default
         elif client_strategy_config is not None:
             self.availability_strategy = client_strategy_config