diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index c0a2d541..c2bf6049 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -123,9 +123,9 @@ jobs:
         # Get current SHA values of files
         echo "Getting SHA for pyproject.toml"
         PYPROJECT_SHA=$(gh api /repos/$GITHUB_REPOSITORY/contents/pyproject.toml --jq '.sha')
-        echo "Getting SHA for __init__.py"
-        INIT_SHA=$(gh api /repos/$GITHUB_REPOSITORY/contents/src/claude_code_sdk/__init__.py --jq '.sha')
-        
+        echo "Getting SHA for _version.py"
+        VERSION_SHA=$(gh api /repos/$GITHUB_REPOSITORY/contents/src/claude_code_sdk/_version.py --jq '.sha')
+
         # Commit pyproject.toml via GitHub API (this creates signed commits)
         message="chore: bump version to ${{ env.VERSION }}"
         base64 -i pyproject.toml > pyproject.toml.b64
@@ -136,15 +136,15 @@ jobs:
           -F content=@pyproject.toml.b64 \
           -f sha="$PYPROJECT_SHA" \
           -f branch="$BRANCH_NAME"
-        
-        # Commit __init__.py via GitHub API
-        base64 -i src/claude_code_sdk/__init__.py > init.py.b64
+
+        # Commit _version.py via GitHub API
+        base64 -i src/claude_code_sdk/_version.py > version.py.b64
         gh api \
           --method PUT \
-          /repos/$GITHUB_REPOSITORY/contents/src/claude_code_sdk/__init__.py \
+          /repos/$GITHUB_REPOSITORY/contents/src/claude_code_sdk/_version.py \
           -f message="$message" \
-          -F content=@init.py.b64 \
-          -f sha="$INIT_SHA" \
+          -F content=@version.py.b64 \
+          -f sha="$VERSION_SHA" \
           -f branch="$BRANCH_NAME"
         
         # Create PR using GitHub CLI
@@ -152,7 +152,7 @@ jobs:
         
         ## Changes
         - Updated version in \`pyproject.toml\`
-        - Updated version in \`src/claude_code_sdk/__init__.py\`
+        - Updated version in \`src/claude_code_sdk/_version.py\`
         
         ## Release Information
         - Published to PyPI: https://pypi.org/project/claude-code-sdk/${{ env.VERSION }}/
diff --git a/scripts/update_version.py b/scripts/update_version.py
index 9d92a817..18a22a6f 100755
--- a/scripts/update_version.py
+++ b/scripts/update_version.py
@@ -11,7 +11,7 @@ def update_version(new_version: str) -> None:
     # Update pyproject.toml
     pyproject_path = Path("pyproject.toml")
     content = pyproject_path.read_text()
-    
+
     # Only update the version field in [project] section
     content = re.sub(
         r'^version = "[^"]*"',
@@ -20,14 +20,14 @@ def update_version(new_version: str) -> None:
         count=1,
         flags=re.MULTILINE
     )
-    
+
     pyproject_path.write_text(content)
     print(f"Updated pyproject.toml to version {new_version}")
-    
-    # Update __init__.py
-    init_path = Path("src/claude_code_sdk/__init__.py")
-    content = init_path.read_text()
-    
+
+    # Update _version.py
+    version_path = Path("src/claude_code_sdk/_version.py")
+    content = version_path.read_text()
+
     # Only update __version__ assignment
     content = re.sub(
         r'^__version__ = "[^"]*"',
@@ -36,9 +36,9 @@ def update_version(new_version: str) -> None:
         count=1,
         flags=re.MULTILINE
     )
-    
-    init_path.write_text(content)
-    print(f"Updated __init__.py to version {new_version}")
+
+    version_path.write_text(content)
+    print(f"Updated _version.py to version {new_version}")
 
 
 if __name__ == "__main__":
diff --git a/src/claude_code_sdk/__init__.py b/src/claude_code_sdk/__init__.py
index b2d5ac2a..639c2c5c 100644
--- a/src/claude_code_sdk/__init__.py
+++ b/src/claude_code_sdk/__init__.py
@@ -12,6 +12,7 @@
     ProcessError,
 )
 from ._internal.transport import Transport
+from ._version import __version__
 from .client import ClaudeSDKClient
 from .query import query
 from .types import (
@@ -274,11 +275,10 @@ async def call_tool(name: str, arguments: dict[str, Any]) -> Any:
     return McpSdkServerConfig(type="sdk", name=name, instance=server)
 
 
-__version__ = "0.0.23"
-
 __all__ = [
     # Main exports
     "query",
+    "__version__",
     # Transport
     "Transport",
     "ClaudeSDKClient",
diff --git a/src/claude_code_sdk/_internal/transport/subprocess_cli.py b/src/claude_code_sdk/_internal/transport/subprocess_cli.py
index 0b0cb785..c701bb37 100644
--- a/src/claude_code_sdk/_internal/transport/subprocess_cli.py
+++ b/src/claude_code_sdk/_internal/transport/subprocess_cli.py
@@ -16,6 +16,7 @@
 
 from ..._errors import CLIConnectionError, CLINotFoundError, ProcessError
 from ..._errors import CLIJSONDecodeError as SDKJSONDecodeError
+from ..._version import __version__
 from ...types import ClaudeCodeOptions
 from . import Transport
 
@@ -187,6 +188,7 @@ async def connect(self) -> None:
                 **os.environ,
                 **self._options.env,  # User-provided env vars
                 "CLAUDE_CODE_ENTRYPOINT": "sdk-py",
+                "CLAUDE_AGENT_SDK_VERSION": __version__,
             }
 
             if self._cwd:
diff --git a/src/claude_code_sdk/_version.py b/src/claude_code_sdk/_version.py
new file mode 100644
index 00000000..0ff45304
--- /dev/null
+++ b/src/claude_code_sdk/_version.py
@@ -0,0 +1,3 @@
+"""Version information for claude-code-sdk."""
+
+__version__ = "0.0.23"