docs: add reasoningEffort documentation to SDK READMEs

Document the new reasoningEffort/reasoning_effort option in SessionConfig
for all SDK clients (Node.js, Python, Go, .NET).

Author: friggeri

dotnet/README.md

@@ -93,6 +93,7 @@ Create a new conversation session.
 
 - `SessionId` - Custom session ID
 - `Model` - Model to use ("gpt-5", "claude-sonnet-4.5", etc.)
+- `ReasoningEffort` - Reasoning effort level for models that support it ("low", "medium", "high", "xhigh"). Use `ListModelsAsync()` to check which models support this option.
 - `Tools` - Custom tools exposed to the CLI
 - `SystemMessage` - System message customization
 - `AvailableTools` - List of tool names to allow

go/README.md

@@ -102,6 +102,7 @@ func main() {
 **SessionConfig:**
 
 - `Model` (string): Model to use ("gpt-5", "claude-sonnet-4.5", etc.). **Required when using custom provider.**
+- `ReasoningEffort` (string): Reasoning effort level for models that support it ("low", "medium", "high", "xhigh"). Use `ListModels()` to check which models support this option.
 - `SessionID` (string): Custom session ID
 - `Tools` ([]Tool): Custom tools exposed to the CLI
 - `SystemMessage` (\*SystemMessageConfig): System message configuration
@@ -114,6 +115,7 @@ func main() {
 **ResumeSessionConfig:**
 
 - `Tools` ([]Tool): Tools to expose when resuming
+- `ReasoningEffort` (string): Reasoning effort level for models that support it
 - `Provider` (\*ProviderConfig): Custom API provider configuration (BYOK). See [Custom Providers](#custom-providers) section.
 - `Streaming` (bool): Enable streaming delta events
 

nodejs/README.md

@@ -88,6 +88,7 @@ Create a new conversation session.
 
 - `sessionId?: string` - Custom session ID
 - `model?: string` - Model to use ("gpt-5", "claude-sonnet-4.5", etc.). **Required when using custom provider.**
+- `reasoningEffort?: "low" | "medium" | "high" | "xhigh"` - Reasoning effort level for models that support it. Use `listModels()` to check which models support this option.
 - `tools?: Tool[]` - Custom tools exposed to the CLI
 - `systemMessage?: SystemMessageConfig` - System message customization (see below)
 - `infiniteSessions?: InfiniteSessionConfig` - Configure automatic context compaction (see below)

python/README.md

@@ -101,6 +101,7 @@ await client.stop()
 **SessionConfig Options (for `create_session`):**
 
 - `model` (str): Model to use ("gpt-5", "claude-sonnet-4.5", etc.). **Required when using custom provider.**
+- `reasoning_effort` (str): Reasoning effort level for models that support it ("low", "medium", "high", "xhigh"). Use `list_models()` to check which models support this option.
 - `session_id` (str): Custom session ID
 - `tools` (list): Custom tools exposed to the CLI
 - `system_message` (dict): System message configuration