fix: expose transport interface

src/claude_code_sdk/__init__.py

@@ -11,6 +11,7 @@
     ProcessError,
 )
 from ._internal.client import InternalClient
+from ._internal.transport import Transport
 from .types import (
     AssistantMessage,
     ClaudeCodeOptions,
@@ -31,6 +32,8 @@
 __all__ = [
     # Main function
     "query",
+    # Transport
+    "Transport",
     # Types
     "PermissionMode",
     "McpServerConfig",
@@ -54,7 +57,7 @@
 
 
 async def query(
-    *, prompt: str, options: ClaudeCodeOptions | None = None
+    *, prompt: str, options: ClaudeCodeOptions | None = None, transport: Transport | None = None
 ) -> AsyncIterator[Message]:
     """
     Query Claude Code.
@@ -69,6 +72,8 @@ async def query(
                  - 'acceptEdits': Auto-accept file edits
                  - 'bypassPermissions': Allow all tools (use with caution)
                  Set options.cwd for working directory.
+        transport: Optional transport implementation. If provided, this will be used
+                  instead of the default transport selection based on options.
 
     Yields:
         Messages from the conversation
@@ -89,6 +94,16 @@ async def query(
             )
         ):
             print(message)
+
+        # With custom transport
+        async for message in query(
+            prompt="Hello",
+            transport=MyCustomTransport()
+        ):
+            print(message)
+
+        async for message in query(prompt="Hello", transport=transport):
+            print(message)
         ```
     """
     if options is None:
@@ -98,5 +113,5 @@ async def query(
 
     client = InternalClient()
 
-    async for message in client.process_query(prompt=prompt, options=options):
+    async for message in client.process_query(prompt=prompt, options=options, transport=transport):
         yield message

src/claude_code_sdk/_internal/client.py

@@ -15,6 +15,7 @@
     ToolUseBlock,
     UserMessage,
 )
+from .transport import Transport
 from .transport.subprocess_cli import SubprocessCLITransport
 
 
@@ -25,22 +26,26 @@ def __init__(self) -> None:
         """Initialize the internal client."""
 
     async def process_query(
-        self, prompt: str, options: ClaudeCodeOptions
+        self, prompt: str, options: ClaudeCodeOptions, transport: Transport | None = None
     ) -> AsyncIterator[Message]:
         """Process a query through transport."""
 
-        transport = SubprocessCLITransport(prompt=prompt, options=options)
+        # Use provided transport or choose one based on configuration
+        if transport is not None:
+            chosen_transport = transport
+        else:
+            chosen_transport = SubprocessCLITransport(prompt=prompt, options=options)
 
         try:
-            await transport.connect()
+            await chosen_transport.connect()
 
-            async for data in transport.receive_messages():
+            async for data in chosen_transport.receive_messages():
                 message = self._parse_message(data)
                 if message:
                     yield message
 
         finally:
-            await transport.disconnect()
+            await chosen_transport.disconnect()
 
     def _parse_message(self, data: dict[str, Any]) -> Message | None:
         """Parse message from CLI output, trusting the structure."""

src/claude_code_sdk/_internal/transport/__init__.py

@@ -36,4 +36,5 @@ def is_connected(self) -> bool:
         pass
 
 
+# Import implementations
 __all__ = ["Transport"]

src/claude_code_sdk/types.py

@@ -126,4 +126,4 @@ class ClaudeCodeOptions:
     disallowed_tools: list[str] = field(default_factory=list)
     model: str | None = None
     permission_prompt_tool_name: str | None = None
-    cwd: str | Path | None = None
+    cwd: str | Path | None = None